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1
Du, Bin, Haibo Bai, Minglei Zhai, and Shixin He. "Experimental Study on Dynamic Compression Characteristics of Red Sandstone under Wetting-Drying Cycles." Advances in Civil Engineering 2020 (December 14, 2020): 1–10. http://dx.doi.org/10.1155/2020/6688202.
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To study the influence of wetting-drying cycles on dynamic mechanical properties of rock masses, the impact compression tests of red sandstone samples were carried out by using a split Hopkinson pressure bar (SHPB) apparatus with a diameter of 50 mm. The results showed that under the same number of wetting-drying cycles, the dynamic compressive strength of red sandstone increased exponentially with the strain rate, and the sensitivity of the strain rate decreased with the increase of wetting-drying cycles. The deterioration effect of wetting-drying cycles was significant, and the dynamic and static compressive strength decreased with the increase of wetting-drying cycles; the higher the strain rate, the stronger the sensitivity to wetting-drying cycles. Besides, the influence of wetting-drying cycles and strain rate was comprehensively studied, and the equation of dynamic compressive strength of red sandstone was obtained. After different wetting-drying cycles, the fractal characteristics of red sandstone dynamic fragmentation were obvious, and the fractal dimension was 2.02–2.80, and the fractal dimension increased logarithmically with the strain rate. Finally, the internal microstructure of red sandstone after different wetting-drying cycles was analyzed, and the degradation mechanism of the rock by the cycles was discussed.
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Wang, Jian, Dexter B. Watts, Qinqian Meng, Fan Ma, Qingfeng Zhang, Penghui Zhang, and Thomas R. Way. "Influence of Soil Wetting and Drying Cycles on Soil Detachment." AgriEngineering 4, no. 2 (June 16, 2022): 533–43. http://dx.doi.org/10.3390/agriengineering4020036.
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Agricultural soils undergo periods of saturation followed by desiccation throughout the course of a growing season. It is believed that these periods of wetting and drying influence soil structure and may affect the rate of soil detachment. Thus, an experiment was conducted to investigate the influence of a disturbed soil (soil sieved to simulate tillage) subjected to various wetting and drying cycles, on soil bulk density and the resistance to soil detachment with runoff. Seven treatments consisting of wetting and drying cycles ranging from 0 to 6 cycles were evaluated under laboratory conditions using an experimental flume apparatus. A Richards growth model proposed for predicting the influence of wetting and drying on soil detachment was also evaluated. Results showed that the soil bulk density increased as the number of wetting and drying cycles increased. The soil detachment rate decreased as the number of wetting and drying cycles increased. Moreover, initial soil detachment (occurring as soon as runoff began) rates were high for 1 to 3 wetting and drying cycles, while the rate of initial detachment decreased after the third cycle. For example, soils with two and three wetting and drying cycles took 6.5 and 7 min to reach the maximum 1 cm souring depth, respectively, while the soils subjected to four or more wetting and drying cycles did not reach the maximum 1 cm depth during the 15 min runoff experiment. In addition, the proposed S-Shaped Richards growth model was a good predictor for estimating the soil detachment of soils experiencing various wetting and drying cycles. Findings from this study suggest that more attention should be given to the influence that soil wetting and drying have on the prediction of soil detachment. Information from this study is expected to be useful for improving soil management strategies for reducing soil erosion.
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Hu, Zhi, Kai Peng, Lihua Li, Qiang Ma, Henglin Xiao, Zhichao Li, and Pinbo Ai. "Effect of Wetting-Drying Cycles on Mechanical Behaviour and Electrical Resistivity of Unsaturated Subgrade Soil." Advances in Civil Engineering 2019 (June 16, 2019): 1–10. http://dx.doi.org/10.1155/2019/3465327.
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Compacted soil is widely used in road and railway subgrade, while alternation of seasons can cause fluctuations in moisture content of soil (i.e., wetting-drying cycles) and influence the performance of soil. In order to research the effect of wetting-drying cycles on mechanical behaviour and electrical resistivity of compacted unsaturated subgrade soil, wetting-drying tests considering different number and cyclic amplitude were conducted on compacted unsaturated clay specimens, and the electrical resistivity and unconfined compressive strength of soil were measured in this study. The AC (alternative current) two-electrode method was applied in the resistivity measurement. The experimental results show that increasing number and cyclic amplitude of wetting-drying cycles can both reduce the strength and electrical resistivity of the compacted unsaturated specimens. After 3-4 wetting-drying cycles, the strength and electrical resistivity tend to be constant value. The change of pore structure can be the key factor leading to the reduction of electrical resistivity of soil subjected to wetting-drying cycles and consequently causing the decrease of soil strength in the present study. Thus, the electrical resistivity can be adopted to indirectly assess the mechanical behaviour of unsaturated compacted soil after wetting-drying cycles.
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Zhou, Yan-Ming, Zong-Wei Deng, Zi-Jian Fan, and Wen-Jie Liu. "Shear Strength Deterioration of Compacted Residual Soils under a Wind Turbine due to Drying-Wetting Cycles and Vibrations." Advances in Civil Engineering 2021 (December 13, 2021): 1–10. http://dx.doi.org/10.1155/2021/8628842.
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The soil beneath a wind turbine withstands not only environmental impacts but also continuous vibrations transmitted from the superstructure. This paper presents an experimental study of the deterioration characteristics of shear strengths of residual soils affected by drying-wetting cycles and continuous vibrations. A series of triaxial tests were performed on compacted residual soil specimens after various drying-wetting cycles and vibrations. The influences of drying-wetting cycles and vibrations on the shear strengths of residual soils with different compaction degrees were analyzed. The results demonstrate that the shear strength and cohesion of compacted residual soils decreased as the number of drying-wetting cycles increased, and they tended to be stable after three drying-wetting cycles. The angle of internal friction decreased linearly with the reduction of compaction degree but was generally not affected by drying-wetting cycles. The shear strength of compacted residual soils also decreased because of continuous vibrations. After 10000 vibrations, the strength was stabilized gradually. Both the cohesion and angle of internal friction showed dynamic attenuation phenomenon. Finally, a modified Mohr–Coulomb strength equation considering the effects of drying-wetting cycles and vibrations was established. This equation could be used to predict the shear strength of compacted residual soils and further estimate the embedded depth of wind turbine foundations.
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Li, Shuyi, Zhilei He, Peng Zhu, Longxi Mei, Shaojun Zeng, and Siwei Wang. "Experimental Study on the Triaxial Compression Properties of Coarse-Grained Filling Soil under Drying–Wetting Cycles." Geofluids 2022 (November 14, 2022): 1–14. http://dx.doi.org/10.1155/2022/1452916.
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To explore the mechanical properties of coarse-grained filling soil in the hydrofluctuation belt of the Baihetan reservoir, a fast drying–wetting cycle method for large-scale triaxial tests was developed and a series of large-scale triaxial compression tests of coarse-grained soil were conducted under drying–wetting cycles. The results show that the drying–wetting cycles and the confining pressure are both important factors affecting the mechanical properties of coarse-grained soil. The influences of the first and second cycles on the deviatoric stress–strain curve of the coarse-grained soil are the greatest, while the influences of the third to seventh cycles tend to be stable. The peak strain is not affected by the drying–wetting cycles but only increases with increasing confining pressure. The axial strain and volumetric strain at the volume expansion point decrease with increasing number of drying–wetting cycles but increase with increasing confining pressure. The secant modulus of the peak point decreases with increasing number of drying–wetting cycles, and the initial tangent modulus decreases slightly. The influence of the drying–wetting cycles on the cohesion of the coarse-grained soil is greater than that on the internal friction angle. The typical “bulging” phenomenon occurred after the specimens were destroyed. A damage constitutive equation was developed by introducing a damage variable into the hyperbolic model to reflect the influence of the number of drying–wetting cycles. The model parameters were obtained and the proposed model was verified by fitting the experimental results.
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Xu, Xu-tang, Dao-qi Liu, Zhen-xing Xian, Feng Yang, Wen-bin Jian, Xiang Xu, and Jian-bin Huang. "Influence of Drying–Wetting Cycles on the Water Retention and Microstructure of Residual Soil." Geofluids 2022 (August 30, 2022): 1–15. http://dx.doi.org/10.1155/2022/9948658.
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Due to frequent changes in the humid and hot environment, the residual soil with a particle-size distribution (PSD) from gravel to clay experiences multiple drying–wetting cycles. The pressure plate test and nuclear magnetic resonance (NMR) spectroscopy were used to investigate the influence of drying–wetting cycles on the soil–water characteristic curve (SWCC) and pore-size distribution (POSD) of undisturbed residual soil. The results showed that the water-holding capacity of the residual soil decreased as the number of drying–wetting cycles increased and gradually stablilized, and then the van Genuchten (VG) model was found to perform well on the SWCC during the drying–wetting processes. The NMR results indicated a double-pore structure, and the porosity of the residual soil as well as the internal water content increased smoothly with more drying–wetting cycles. The obtained POSD curve of soil implied that drying–wetting cycles had a more obvious effect on small pores and macro-pores than on micro-pores and meso-pores. Theoretical calculations evinced that the product of the matric suction and relaxation time should be constant at a constant temperature. However, the experimental results did not effectively reflect such a relation between the matric suction and relaxation time. A modified VG model based on the cumulative pore volume was utilized to describe the POSD under drying–wetting cycles. Subsequently, the proposed Rational2D surface equation was used to accurately reflect the internal relationship between the SWCC and POSD curve under different numbers of drying–wetting cycles. Moreover, the fractal model for the SWCC derived from the capillary theory confirmed that the matric suction had a strong linear relationship with the relative volumetric water content in the log-log scale. Also, the fractal dimension can be approximated as a constant, because its attenuation is small with more drying–wetting cycles.
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Hao, Ruihua, Zizhao Zhang, Zezhou Guo, Xuebang Huang, Qianli Lv, Jiahao Wang, and Tianchao Liu. "Investigation of Changes to Triaxial Shear Strength Parameters and Microstructure of Yili Loess with Drying–Wetting Cycles." Materials 15, no. 1 (December 29, 2021): 255. http://dx.doi.org/10.3390/ma15010255.
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This research examined the drying–wetting cycles induced changes in undrained triaxial shear strength parameters and microstructural changes of Yili loess. The drying–wetting cycles were selected as 0, 1, 3, 5, 10, 20 and 30. Then, we collected Yili loess samples and performed unconsolidated-undrained (U-U) triaxial shearing tests to ascertain the variation in shear strength parameters with drying–wetting cycles. Additionally, we investigated the microstructural changes of Yili loess samples under drying–wetting cycles simultaneously via nuclear magnetic resonance (NMR) and scanning electron electroscopy (SEM). Finally, we established a grey correlation model between shear strength and microstructural parameters. Under U-U conditions, the prime finding was that the loess’s shear strength parameters changed overall after drying–wetting cycles; in particular, the internal friction angle φ dropped significantly while the cohesion c changed only slightly during cycles. For all the cycles, the first cycle gave the highest change. Soil morphology deterioration was evident at the initial stage of cycles. During the entire drying–wetting cyclic process, pore size distribution showed progressive variance from two-peak to a single-peak pattern, while both porosity and the fractal dimension of pores increased gradually towards stability. Soil particle morphology became slowly simple and reached the equilibrium state after 20 drying–wetting cycles. Under cyclic drying–wetting stress, the shear strength parameter changes were significantly correlated to microstructural modifications. This investigation was related to loess in the westerly region. The findings were expected to provide new insight into establishment of the connection between microstructure and macro stress–strain state of loess. To some extent, it provided a theoretical basis for the prevention and control of loess engineering geological disasters in Yili, Xinjiang and other areas with similar climate and soil types.
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Qin, Zhe, Xuxin Chen, and Houli Fu. "Damage Features of Altered Rock Subjected to Drying-Wetting Cycles." Advances in Civil Engineering 2018 (2018): 1–10. http://dx.doi.org/10.1155/2018/5170832.
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An abandoned open pit was used as a tailing pond for a concentrating mill, with the height of the water surface subject to cyclic fluctuation. The effects of drying and wetting cycles on the mechanical parameters of pit rock were tested. Interactions of the hydrochemical environment, due to the dissolution of tailings, and drying and wetting cycles caused degradation of mechanical properties in the rock. It was found that uniaxial compressive strength and elastic modulus decreased as the number of dry/wet cycles increased. The quantitative relationship between the mechanical parameters and the number of dry/wet cycles was indicated by an exponential function. In addition to uniaxial testing, cohesion and the internal friction angle were determined through triaxial testing. The shear strength index deteriorated under the drying and wetting cycles. The hydrochemical environment also negatively affected the mechanical parameters. Potential effects between drying and wetting cycles and slope displacement were analyzed by on-site monitoring. The results show that the displacement increased because of the drying and wetting cycles, which may lead to sudden failure of the slope.
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Mao, Yun Cheng, Guo Yu Li, Jun Xia Lei, Li Ru Zhang, and Zhao Yu Chen. "Experimental Study on the Effects of Wetting-Drying Cycles of Compacted Loess." Advanced Materials Research 831 (December 2013): 326–30. http://dx.doi.org/10.4028/www.scientific.net/amr.831.326.
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It rains more concentrated in the summer with high temperature and strong evaporation in Gansu province, wetting-drying cycles usually occur in the embankment. Different collapse and uneven settlement appeared on the embankment in loess areas. Based on those engineering disease, through wetting-drying cycles tests of compacted loess, results show that void ratio increased, dry density decreased and cohesion significantly reduced with violent wetting-drying cycles. This illustrates that wetting-drying cycle has a significant impact on compacted loess and makes well-compacted loess with collapsibility again, it is the important reason of uneven settlement of embankment in northwest loess areas.
10
Kong, Lingwei, Hossain Md Sayem, and Huihui Tian. "Influence of drying–wetting cycles on soil-water characteristic curve of undisturbed granite residual soils and microstructure mechanism by nuclear magnetic resonance (NMR) spin-spin relaxation time (T2) relaxometry." Canadian Geotechnical Journal 55, no. 2 (February 2018): 208–16. http://dx.doi.org/10.1139/cgj-2016-0614.
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Due to the formational environment and climatic variability, granite residual soils with grain-size distribution ranging from gravel to clay undergo multiple drying–wetting cycles. The influences of multiple drying–wetting cycles on the soil-water characteristic curve (SWCC) and pore-size distribution (POSD) of undisturbed granite residual soils are investigated using the pressure plate test and nuclear magnetic resonance (NMR) spin-spin relaxation time (T2) distribution measurement, respectively. Results show that the water-retention capacity and air-entry value decrease and pores become more uniform with increasing drying–wetting cycles. After four drying–wetting cycles, the soil reaches a nearly constant state. The POSD change of multiple drying–wetting cycle samples is consistent with the SWCC of the soils. Furthermore, a modified van Genuchten model in terms of cumulative pore volume is used to obtain the best-fit POSD of the drying–wetting cycle samples. The shape and changing tendency of both curves of SWCC and POSD are quite similar and achieved a better correlation. It can be concluded that the SWCC is strongly dependent on the POSD of the soil and NMR T2 relaxometry can be used as an alternative to the assessment of microstructural variation of residual soils subjected to the periodic drying and wetting process.
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Li, Shengwei, Cunbao Li, Wei Yao, Ru Zhang, Jing Xie, Junchen Zhang, Qiang Liu, and Zhaopeng Zhang. "Impact of wetting-drying cycles on dynamic tensile strength of rock." Thermal Science 23, Suppl. 3 (2019): 815–20. http://dx.doi.org/10.2298/tsci180411115l.
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To study the effect of wetting-drying cycles on dynamic tensile strength of rock, dynamic indirect tension test of sandstone samples after 0, 1, 3, and 5 wetting-drying cycles was conducted. Tensile failure was observed by digital image correlation. The result shows that failure appears in the center of the samples initially, consistent with tensile strain field results obtained by digital image correlation. An empirical formula was derived to link loading rate and dynamic tensile strength of rock after wetting-drying cycles. As the loading rate increases, tensile strength increases significantly. Tensile strength reduces as the number of wetting-drying cycles increases. These results provide reference data for complex engineering problems such as those that occur in coal mining, tunneling and water conservancy.
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Salehian Dastjerdi, Maryam, and Abbas Hemmat. "Evaluation of load support capacity of remoulded fine and coarse textured soils as affected by wetting and drying cycles." Soil Research 53, no. 5 (2015): 512. http://dx.doi.org/10.1071/sr14209.
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Soils of south of Iran used for sugarcane production are frequently exposed to wetting and drying cycles under flood irrigation. The effects of this process on estimation of the load support capacity (pre-compaction stress; σpc) of two soils using plate sinkage test (PST) and confined compression test (CCT) were studied. Large reconstructed specimens of topsoils were subjected to 5 wetting and drying cycles. The specimens, with/without wetting and drying cycles, were then compressed under two pre-loads (100 and 200 kPa) at two water contents (0.9 PL and 1.1 PL, where PL is plastic limit). The centre section of the preloaded soil specimens was firstly submitted to a 50 mm PST; then immediately one cylindrical sample was cored for CCT. The results indicated that for both soils, without wetting and drying cycles, σpc estimated from PST did not show any significant difference with the values of preload. This method can, therefore, be used to determine the load support capacity for tilled soils. However, wetting and drying cycles caused a significant over-estimation of σpc by PST. Thus, the concept of pre-compaction stress does not account for the effects of changes in soil structure due to wetting and drying.
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Dao, Huan Minh, Anh Thuc Thi Nguyen, and Tuan Manh Do. "Effect of wetting-drying cycles on surface cracking and swell-shrink behavior of expansive soil modified with ionic soil stabilizer." Journal of Mining and Earth Sciences 61, no. 6 (December 31, 2020): 1–13. http://dx.doi.org/10.46326/jmes.2020.61(6).01.
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This paper presents the results of an experimental investigation of the effect of wetting-drying cycles on the surface cracking and swell-shrink behavior of modified expansive soils. An image processing technique was employed to understand this effect by quantifying the surface crack area density, crack number, crack length, mean crack width, and absolute shrinkage. Parameters such as height, the relative rate of expansion, and linear shrinkage were used to characterize the effect of wetting-drying cycles on the swell-shrink behavior of the specimens subjected to various overburden pressures. The results showed that the increase in the number of wetting/drying cycles accelerated the crack growth and led to the increased crack number, total crack length, and surface crack area density. Moreover, as the number of wetting/drying cycles increased, the absolute shrinkage to be on the rise, and the mean crack width exhibited fluctuation characteristics. Furthermore, the moisture content was inversely related to the crack extent. For the specimens subjected to various overburden pressures, the height and the moisture content showed a good linear relationship. With the increase in wetting/drying cycles, the relative rate of expansion of the specimen decreased. Additionally, a larger overburden pressure resulted in a lower relative rate of expansion; however, as the number of wetting/drying cycles increased, the relative rate of linear shrinkage increased and then decreased.
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Ma, Junwei, Xiaoxu Niu, Chengren Xiong, Sha Lu, Ding Xia, Bocheng Zhang, and Huiming Tang. "Experimental Investigation of the Physical Properties and Microstructure of Slate under Wetting and Drying Cycles Using Micro-CT and Ultrasonic Wave Velocity Tests." Sensors 20, no. 17 (August 27, 2020): 4853. http://dx.doi.org/10.3390/s20174853.
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Cyclic wetting and drying processes have been considered as important factors that accelerate the weathering process and have deteriorative effects on rock properties. In the present study, a fully nondestructive and noninvasive testing approach utilizing micro-CT and ultrasonic wave velocity tests was employed to investigate the microstructure of slate under wetting and drying cycles. We studied variations in the physical properties, including the dry weight and the velocities of P- and S-waves versus the number of wetting and drying cycles. The internal microstructural distributions were visualized and quantified by the 3D reconstruction and hybrid image segmentation of CT images. The degree of deterioration caused by wetting and drying cycles was reflected by exponential decreases of physical properties, including dry weight and velocities of the P- and S-waves. Parameters relating to the microfracture diameter, volume, etc. were quantified. The nondestructive and noninvasive testing approach utilizing micro-CT and ultrasonic wave velocity tests has potential for the detection and visualization of the internal microstructure of rock under wetting and drying cycles.
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Downs, Michael P., and Paul B. Cavers. "Effects of wetting and drying on seed germination and seedling emergence of bull thistle, Cirsium vulgare (Savi) Ten." Canadian Journal of Botany 78, no. 12 (December 1, 2000): 1545–51. http://dx.doi.org/10.1139/b00-128.
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Seeds of bull thistle, Cirsium vulgare (Savi) Ten., were exposed to varying numbers of cycles of wetting and drying, in both Petri dishes and pots of soil, to investigate the effects of exposure to such cycles on subsequent germination of the seeds or emergence of the seedlings. Following exposure to the cycles, seeds in Petri dishes were set to germinate in one of four diurnal environments: 20:10°C alternating light and darkness, 20:10°C constant darkness, 30:15°C alternating light and darkness, or 30:15°C constant darkness. Total percent germination was reduced after exposure to eight cycles of wetting and drying, and germination rate was reduced after exposure to two or more cycles. Percent germination was reduced at the higher temperature but light availability had little effect. Reduction in seedling emergence in pots of soil after exposure to an intermediate number of cycles was greater than in Petri dishes but not as great with exposure to eight cycles. Seedling emergence patterns in pots that experienced any wetting-drying treatment were bimodal, with a second pulse of emergence several weeks after the termination of the cycles. This suggests that some seeds were induced into a dormant state through exposure to the cycles of wetting and drying. Such induced dormancy may serve to prevent seed germination in the autumn, promoting an attenuated and intermittent pattern of germination.Key words: Cirsium vulgare, bull thistle, wetting and drying, seed germination, induced dormancy, intermittent germination.
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Chang, Jin, Jieling Ma, and Xianyuan Tang. "Study on Strength Attenuation Characteristics of Residual Expansive Soil under Wetting-Drying Cycles and Low Stress and Its Relationship with Shallow Landslide." Geofluids 2022 (September 14, 2022): 1–10. http://dx.doi.org/10.1155/2022/6277553.
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The rapid development of expansive soil fissures and the attenuation of strength under the action of repeated atmospheric wetting-drying cycles have a very adverse impact on the shallow stability of expansive soil slope. In this study, shear strength test and fissure observation test were performed on typical residual expansive soil specimens at various wetting-drying cycles and low stress. The results show that the shear strength index of residual expansive soil should be obtained according to the high and low stress sections, respectively. The cohesion of the three residual expansive soils decreased to a similar low value range (0~5 kN) at multiple wetting-drying cycles and low stress; the attenuation of cohesion is the main cause of shallow slope collapse. The fissure rate of the specimen surface increases with the increasing number of wetting-drying cycles, and increasing the dry density can significantly inhibit the development of fissures. The repeated wetting-drying cycles leads to the rapid development of slope fissures from the surface to the inside, destroys the internal natural structure of undisturbed expansive soil, reduces the cementation between soil particles, and leads to the decrease of soil cohesion. For slope stability analysis of residual expansive soil, the strength parameters of the specimens with multiple wetting-drying cycles and internal fissure network should be selected according to the overburden pressure of the slope sliding surface. The research results provide a theoretical basis for the stability analysis of shallow landslide of expansive soil slope and slope protection design.
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Nie, Yongpeng, Wankui Ni, Xiangning Li, Haiman Wang, Kangze Yuan, Yexia Guo, and Wenxin Tuo. "The Influence of Drying-Wetting Cycles on the Suction Stress of Compacted Loess and the Associated Microscopic Mechanism." Water 13, no. 13 (June 29, 2021): 1809. http://dx.doi.org/10.3390/w13131809.
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To better understand and analyze the unsaturated stability of loess filling body, it is necessary to study the changes in suction stress before and after the drying-wetting cycles. In this study, the SWCC of compacted loess before and after drying-wetting cycles was tested using the filter paper method. Then, the suction stress was calculated and the microstructure of the loess sample was determined by the SEM and NMR. The results showed that the drying-wetting cycles had an important influence on the SSCC and microstructure of compacted loess. The change in suction stress before and after the drying-wetting cycles can be well explained by the loess microstructure. The drying-wetting cycles did not significantly change the basic trend of the compacted loess's SSCC, but it increased the porosity and the dominant pore diameter of loess, and reduced the suction stress under the same matric suction. The main significant change in suction stress with matric suction occurred within the range of the dominant soil pores. The larger the dominant pore diameter, the smaller the suction stress under the same matric suction. In addition, this study proposes a new method for calculating suction stress based on the PSD parameters.
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Zeng, Ling, Fan Li, Jie Liu, Qianfeng Gao, and Hanbing Bian. "Effect of initial gravimetric water content and cyclic wetting-drying on soil-water characteristic curves of disintegrated carbonaceous mudstone." Transportation Safety and Environment 1, no. 3 (December 12, 2019): 230–40. http://dx.doi.org/10.1093/tse/tdz018.
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Abstract The soil-water characteristic curve (SWCC) is often used to estimate unsaturated soil properties (e.g. strength, permeability, volume change, solute and thermal diffusivity). The SWCC of soil samples is significantly affected by cyclic wetting-drying. To examine how water content and cyclic wetting-drying affect the SWCC of disintegrated carbonaceous mudstone (DCM), SWCC tests were implemented using a pressure-plate apparatus. In addition, SWCC models for DCM considering the initial gravimetric water content and cyclic wetting-drying were developed. The test results showed that the volumetric water content (θ) of the DCM first decreased rapidly and then became stable as matric suction (s) increased. The initial water content affected the SWCC by altering the pore structure of the DCM. For a given number of wetting-drying cycles, the higher the initial water content, the higher the stabilized θ. At a given s value, θ decreased as the number of wetting-drying cycles increased, which suggests that cyclic wetting-drying reduces the water-holding capacity of DCM. The Gardner model for DCM was constructed considering initial water content and cyclic wetting-drying, and was effective at describing and predicting the SWCC model for DCM.
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Huang, Shiyuan, Junjie Wang, Zhenfeng Qiu, and Kai Kang. "Effects of Cyclic Wetting-Drying Conditions on Elastic Modulus and Compressive Strength of Sandstone and Mudstone." Processes 6, no. 12 (November 22, 2018): 234. http://dx.doi.org/10.3390/pr6120234.
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The influence of water on the mechanical properties of rock is vital for determining the rock stability when subjected to changes of water conditions. In this paper, a series of uniaxial compression tests were conducted to investigate effects of cyclic wetting and drying on the mechanical properties of sandstone and mudstone collected from Chongqing city, China. The results showed that both elastic modulus and uniaxial compressive strength of sandstone and mudstone were reduced by wetting and drying cycles, and that the degradation rate of the two mechanic parameters of mudstone was always larger than sandstone. The parameters, including water adsorption, degradation degree of elastic modulus, degradation degree of uniaxial compressive strength, increase with the increase of the wetting-drying cycles (N). The relationship between these three parameters and the value of N + 1 could be well fitted by logarithmic curves. The average degradation degree was also used to describe the degradation of per time wetting-drying cycles. It is found that the average degradation degree of elastic modulus and uniaxial compressive strength decrease with the increase of wetting-drying cycles. Moreover, the relationships between the mechanical properties and the porosity are presented, which can be fitted by linear curves. In the cyclic wetting-drying process, the elastic modulus and the uniaxial compressive strength decreased with the porosity increasing, and the degradation rates of sandstone mechanic parameters were higher than those of mudstone.
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Li, Tao, Yanqing He, Guokun Liu, Binru Li, and Rui Hou. "Experimental Study on Cracking Behaviour and Strength Properties of an Expansive Soil under Cyclic Wetting and Drying." Shock and Vibration 2021 (December 26, 2021): 1–13. http://dx.doi.org/10.1155/2021/1170770.
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Expansive soil is characterized by its unique structural morphology and drastic volume change. With infrastructure increasingly constructed in expansive soil areas, engineering problems caused by the properties of expansive soils have attracted more attention. Cyclic wetting-drying and shear testing were accordingly conducted on an expansive soil from Chengdu area in China. Crack development and shear strength change were analyzed using the Mohr–Coulomb equation for shear strength by fitting the experimental data. The results show the following: (1) With the increase in wetting-drying cycles, the crack ratio increases, the shear strength decreases, and the shear strength parameters gradually decrease at the same rate of change. The applied vertical load reduces the weakening effect of the wetting-drying cycles on the soil structure and strength by restraining the expansion and contraction deformation. (2) By analyzing the number of wetting-drying cycles and the crack images, the crack development (length, direction, etc.) of the expansive soil can be predicted and described. (3) There is a specific linear correlation between the crack ratio and strength that approached a limit value with ongoing wetting-drying cycles. The strength of the expansive soil can therefore be obtained based on crack development, improving the ability of designers to account for the behaviour of expansive soils.
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Yuan, Pu, Ning-Ning Wei, Qin-Yong Ma, and Ju-Cai Chang. "Coupled Effect of Water Temperature and Cyclic Wetting and Drying on Dynamic Mechanical Characteristics of Sandstone." Advances in Civil Engineering 2019 (September 30, 2019): 1–15. http://dx.doi.org/10.1155/2019/8167651.
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Considering the periodical moisture variation in deep rock masses, cyclic wetting and drying under high geothermal condition is a vital issue for the safety and stability of deep rock engineering. To investigate the coupled effect of water temperature and cyclic wetting and drying on dynamic mechanical characteristics of sandstone, dynamic uniaxial compressive tests were carried out under the same loading condition for sandstone specimens subjected to cyclic wetting and drying treatment. When the temperature was 60°C in both wetting and drying processes, cyclic wetting and drying treatment presents a detrimental effect on the tested sandstone. Both physical and dynamic uniaxial compressive characteristics deteriorate in an exponential function with the increase of wetting and drying cycles. Based on SEM image analyses, the initiation and propagation of microcracks is mainly the result of cyclic loading and unloading of tensile stresses induced by water absorption and desorption of kaolinite within sandstone during cyclic wetting and drying treatment. After 15 cycles of wetting and drying, the deterioration of both physical and dynamic uniaxial compressive characteristics first increase then decrease with water temperature in wetting process elevating from 20°C to 98°C. SEM images indicate that more microcracks generate when water temperatures increase from 20°C to 60°C, while the micromorphology is changed and fewer microcracks display due to kaolinite mobilization when water temperature increases from 60°C to 98°C. The threshold value for the effect of water temperature on cyclic wetting and drying is found to be about 60°C for the tested sandstone.
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Choudhary, M. I., A. M. AI-Omran, and A. A. Shalaby. "Physical Properties of Sandy Soil Affected by Soil Conditioner Under Wetting and Drying cycles." Journal of Agricultural and Marine Sciences [JAMS] 3, no. 2 (June 1, 1998): 69. http://dx.doi.org/10.24200/jams.vol3iss2pp69-74.
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Information on the effectiveness of soil conditioners over a prolonged period is scarce. A laboratory experiment was undertaken to evaluate the effectiveness of a polyacrylamide (Broadleaf P4) soil conditioner on the physical properties of sandy soil subjected to wetting and drying cycles. Four concentrations of Broadleaf P4 0, 0.2, 0.4, and 0.6% on dry weight basis were uniformly mixed with a calcareous sandy soil. Addition of Broadleaf P4 to sandy soil increased the water holding capacity, decreased the bulk density, and increased the porosity and void ratio at 0 and 16 wetting and drying cycles. The coefficient of linear extensibility increased considerably with increasing concentrations of the polymer. The addition of polymer at 0 and 16 cycles increased considerably the retention and availability of water in sandy soil. Saturated hydraulic conductivity decreased with increasing concentrations of Broadleaf P4 whereas unsaturated hydraulic conductivity at 0 and 16 cycles showed an increase with increasing soil moisture contents. After I6 wetting and drying cycles, the capacity of the soil to hold water was lost on average by 15.8% when compared to the 0 wetting and drying cycle. The effectiveness of the soil conditioner on bulk density, coefficient of linear extensibility, available water and saturated hydraulic conductivity was reduced on average by 14.1, 24.5, 21.l and 53.7% respectively. The significant changes in soil properties between 0 and 16 cycles suggested that the effectiveness of the conditioner decreased with the application of wetting and drying cycles. However, its effect was still considerable when compared to untreated soil under laboratory conditions.
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Cuisinier, Olivier, and Farimah Masrouri. "Impact of wetting/drying cycles on the hydromechanical behaviour of a treated soil." E3S Web of Conferences 195 (2020): 06008. http://dx.doi.org/10.1051/e3sconf/202019506008.
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The positive effects of lime or cement treatment could be altered by weathering in the very long term. In this context, the main purpose of this study is to examine the impact of wetting/drying cycles on the strength and the hydraulic conductivity of a compacted soil treated with lime and cement. Compacted specimens were cured for 90 days before being exposed up to twelve wetting and drying cycles. A special concern of the study was the experimental method to impose the wetting and drying cycles. Two protocols were employed: one relied on relative humidity control to dry the samples, while the other was based on oven drying. The impact of the cycles was quantified by comparing the performance of the samples exposed to the cycles to the performance of the unsolicited samples. The results showed that the cycles induced a major alteration of the strength of the samples, with both methods. This degradation is associated to a significant increase of the hydraulic conductivity of the samples with the number of cycles.
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Tang, Chuxuan, Zheng Lu, and Hailin Yao. "Effect of Axial Pressure on Lime-Treated Expansive Soil Subjected to Wetting and Drying Cycles." Advances in Civil Engineering 2019 (December 2, 2019): 1–8. http://dx.doi.org/10.1155/2019/3052932.
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The impact of seasonal moisture variation on subgrade soil, including lime-treated expansive soil, has been investigated in many studies. However, when performing wetting and drying cycles, the effect of stress, which decides the behavior and mechanical properties of soil, is usually ignored. In this paper, the effect of axial surcharge pressure on the deformation and resilient modulus of lime-treated expansive soil subjected to wetting and drying cycles was investigated. A self-made apparatus was chosen to apply axial surcharge pressure and precisely control the variation of moisture content. The lime-treated specimens were placed in the self-made apparatus and then subjected to wetting and drying cycles under three different surcharge pressures. The results show that the axial surcharge pressure has a significant influence on the development of axial strain and resilient modulus. In particular, larger surcharge pressure induces accumulate irreversible shrinkage, whereas lower surcharge pressure tends to lead to irreversible swelling. On the contrary, the larger surcharge pressure leads to higher resilient modulus of the tested specimen after wetting and drying cycles.
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Xu, Zhi-Hua, Guang-Liang Feng, Qian-Cheng Sun, Guo-Dong Zhang, and Yu-Ming He. "A Modified Model for Predicting the Strength of Drying-Wetting Cycled Sandstone Based on the P-Wave Velocity." Sustainability 12, no. 14 (July 14, 2020): 5655. http://dx.doi.org/10.3390/su12145655.
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The drying-wetting cycles caused by operation of the Three Gorges Reservoir have considerable effect on the deterioration of reservoir bank rock mass, and the degradation of reservoir rock mass by the drying-wetting cycle is becoming obvious and serious along with the periodic operation. At present, the strength of the rock prediction research mainly focuses on the uniaxial strength, and few studies consider the drying-wetting effect and confining pressure. Therefore, in this paper, typical sandstone from a reservoir bank in the Three Gorges Reservoir area is taken as the research object, while the drying-wetting cycle test, wave velocity test and strength test are carried out for the research on the strength prediction of sandstone under the action of the drying-wetting cycle. The results show that the ultrasonic wave velocity Vp of the sandstone has an exponential function relation with the drying-wetting cycle number n, and the initial stage of drying-wetting cycles has the most significant influence on the wave velocity. Under different confining pressures, the compressive strength of sandstone decreases linearly with the increase of the drying-wetting cycle numbers, and the plastic deformation increases gradually. The damage variable of the sandstone has a power function relation with the increase of drying-wetting cycle numbers. A traditional strength prediction model based on P-wave velocity was established combined with the damage theory and Lemaitre strain equivalence hypothesis; in view of the defects of the traditional strength prediction model, a modified model considering both the drying-wetting cycle number and confining pressures was proposed, where the calculated results of the modified model are closer to the test strength value, and the prediction error is obviously decreased. This indicated that the modified model considering the drying-wetting cycle number and confining pressure is reasonable and feasible.
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Gullà, Giovanni, Maria Clorinda Mandaglio, and Nicola Moraci. "Effect of weathering on the compressibility and shear strength of a natural clay." Canadian Geotechnical Journal 43, no. 6 (June 1, 2006): 618–25. http://dx.doi.org/10.1139/t06-028.
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In situ, seasonal changes expose soils to frequent wettingdryingfreezingthawing cycles. Such processes can favour and trigger shallow instabilities controlled by the weathering process. This paper presents an experimental study carried out to investigate the effects of the weathering process, caused by the wettingdryingfreezingthawing cycles, on the compressibility and shear strength of a natural clay. Several specimens were trimmed from block samples of overconsolidated clays taken from a slope in south Calabria, Italy. Specimens were subjected to wettingdryingfreezingthawing cycles of different durations and then tested with standard equipment (oedometer and direct shear). Test results show that the wettingdryingfreezingthawing cycles caused a change in the initial microstructure that produced a decrease in the compression index and an increase in the swelling index. Moreover, the direct shear test results show a decrease in the peak shear strength and demonstrate that a larger reduction occurs in the first month of weathering cycles. The intense cycles performed in the laboratory produced a decay of compressibility and a shear strength approaching reconstituted values. The conclusions are important when choosing the shear strength parameters required when studying shallow landsliding in clay slopes.Key words: weathered clay, structure, cycle of degradation, shallow instability.
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Zeng, Ling, Jie Liu, Qian-Feng Gao, and Hanbing Bian. "Evolution Characteristics of the Cracks in the Completely Disintegrated Carbonaceous Mudstone Subjected to Cyclic Wetting and Drying." Advances in Civil Engineering 2019 (May 28, 2019): 1–10. http://dx.doi.org/10.1155/2019/1279695.
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Completely disintegrated carbonaceous mudstone, a common embankment material, has significant swelling-shrinkage behavior under cyclic wetting and drying, which often causes the instability of embankments. In this paper, the evolution of the cracks in the completely disintegrated carbonaceous mudstone subjected to cyclic wetting and drying was studied by laboratory tests. The vacuum saturation method and the drying method based on heat lamps and a fan were employed to simulate the wetting and drying processes, respectively. The image processing technique was used to treat the images of the sample surface. Afterward, various geometric parameters of the cracks appeared on the sample surface were measured, and the evolution characteristics of the cracks were analyzed. The results show that with the increase in the number of wetting and drying cycles, the number of cracks on the sample surface gradually increases. After four wetting and drying cycles, the existing cracks produce a large number of small branches, which are connected to form irregular polygonal grids. The development of the cracks in the completely disintegrated carbonaceous mudstone sample can be divided into three stages, i.e., slow development, rapid development, and stable development. Both the surface density of crack and the crack rate first increase and then tend to be stable with the increasing number of wetting and drying cycles. New cracks are mainly generated on the basis of the existing cracks, and some cracks appear to heal under cyclic wetting and drying. The early cracks are mainly developed in the directions of 0°–90° and 300°–360°, and the development rate of the cracks in the directions of 30°, 90°, 140°–150°, and 180°–270° is significantly higher than that of the cracks in other directions.
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Zhang, Junran, Tong Jiang, Xingcui Wang, Chong Liu, and Zhiquan Huang. "Influences of Drying and Wetting Cycles and Compaction Degree on Strength of Yudong Silt for Subgrade and Its Prediction." Advances in Civil Engineering 2018 (July 22, 2018): 1–10. http://dx.doi.org/10.1155/2018/1364186.
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In order to investigate the influences of drying and wetting cycles, initial degree of compaction, and water content on shear strength of the Yudong subgrade silt, a series of direct shear tests were performed at saturated and unsaturated states. The test results show that effects of the drying and wetting cycles, water content, and compaction degree on cohesion are more evident than those on the internal friction angle. According to the test data, a formula for the cohesion was proposed, which accounts for the drying and wetting cycles, water content, and degree of compaction. Because Bishop’s strength formula for unsaturated soils could not be applied to Yudong silt, a formula is given based on Fredlund’s formula for predicting the shear strength of unsaturated Yudong silt from the soil-water characteristic curve.
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Qi, Wei, Ce Wang, Zhanyu Zhang, Mingyi Huang, and Jiahui Xu. "Experimental Investigation on the Impact of Drying–Wetting Cycles on the Shrink–Swell Behavior of Clay Loam in Farmland." Agriculture 12, no. 2 (February 8, 2022): 245. http://dx.doi.org/10.3390/agriculture12020245.
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Soil shrink–swell behavior is a common phenomenon in farmland, which usually alters the process of water and solute migration in soil. In this paper, we report on a phenomenological investigation aimed at exploring the impact of drying–wetting cycles on the shrink–swell behavior of soil in farmland. Samples were prepared using clay loam collected from farmland and subjected to four drying–wetting cycles. The vertical deformation of soil was measured by a vernier caliper, and the horizontal deformation was captured by a digital camera and then calculated via an image processing technique. The results showed that the height, equivalent diameter, volume and shrinkage-swelling potential of the soil decreased with the repeated cycles. Irreversible deformation (shrinkage accumulation) was observed during cycles, suggesting that soil cracks might form owing to previous drying rather than current drying. The vertical shrinkage process consisted of two stages: a declining stage and a residual stage, while the horizontal shrinkage process had one more stage, a constant stage at the initial time of drying. The VG-Peng model fit the soil shrinkage curves very well, and all shrinkage curves had four complete shrinkage zones. Drying–wetting cycles had a substantial impact on the soil shrinkage curves, causing significant changes in the distribution of void ratio and moisture ratio in the four zones. However, the impact weakened as the number of cycles increased because the soil structure became more stable. Vertical shrinkage dominated soil deformation at the early stage of drying owing to the effect of gravity, while nearly isotropic shrinkage occurred after entering residual shrinkage. Our study revealed the irreversible deformation and deformation anisotropy of clay loam collected from farmland during drying–wetting cycles and analyzed the shrink–swell behavior during cycles from both macroscopic and microscopic points of view. The results are expected to improve the understanding of the shrink–swell behavior of clay loam and the development of soil desiccation cracks, which will be benefit research on water and solute migration in farmland.
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Chu, Chengfu, Meihuang Zhan, Qi Feng, Dong Li, Long Xu, Fusheng Zha, and Yongfeng Deng. "Effect of Drying-Wetting Cycles on Engineering Properties of Expansive Soils Modified by Industrial Wastes." Advances in Materials Science and Engineering 2020 (December 7, 2020): 1–9. http://dx.doi.org/10.1155/2020/5602163.
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The swelling properties of expansive soils can be reduced by the addition of modifiers. Nevertheless, the performance deterioration after modification occurs when weathering for a long term. Therefore, in this study, the effect of drying-wetting cycles on swelling behaviour and compressibility of modified expansive soils with the iron tailing sand and calcium carbide slag has been investigated. The swelling potential initially increases and subsequently decreases with the increasing number of cycles, reaches the peak at the seventh cycle, and tends to equilibrium after the tenth cycle. These results show that drying-wetting cycles will destroy the soil structure. The compressibility of modified expansive soils increases with the drying-wetting cycles, where an empirical formula between compressibility and the cycle number was established. Microstructural analysis is performed using mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). The results of microstructural analysis show a tendency of degradation process.
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Yarbaş, Necmi, and Ekrem Kalkan. "Effects of Quartzite on the Desiccation Cracks of Clayey Soils Exposed to Wetting-Drying Cycles." International Journal of Science and Engineering Applications 11, no. 01 (January 2022): 31–34. http://dx.doi.org/10.7753/ijsea1101.1005.
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The compacted clayey soils crack on drying because of their high swelling potential, and their hydraulic conductivities increase. To solve this problem, it is essential to stabilize the clayey soils using additive materials. The aim of this study is to examine the suitability of quartzite as a stabilization material to reduce the development of desiccation cracks in compacted clayey liner and cover systems. Experimental study was conducted to investigate the effect of wetting-drying cycles on the initiation and evolution of cracks in compacted clayey soils. For experimental studies, seven samples were prepared stabilized by using 0%, 2.5%, 5%, 7,5%, 10%, 12,5% and 15% quartzite and then they were subjected to four subsequent wetting-drying cycles. The results show that quartzite decreases the development of desiccation cracks on the surface of compacted samples. It is concluded that quartzite as a geological material can be successfully used to reduce the development of desiccation cracks in compacted clayey liner and cover systems exposed wetting-drying cycles.
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Liang, Wei, Ke Li, Jiashun Luo, Mengtang Xu, and Fushou Feng. "Microscopic Response of Limestone Physical Deterioration under Water-Rock Alternation in the Acidic Environment." Geofluids 2022 (August 22, 2022): 1–10. http://dx.doi.org/10.1155/2022/7486878.
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In order to investigate the microscopic response mechanism of limestone deterioration under alternating water-rock action in the acidic environment, the porosity, water absorption, mass loss characteristic, and microcrack propagation characteristic were analyzed by laboratory wetting-drying cyclic tests. The results show that, with increasing the number of cycles, the porosity, water absorption, and mass deterioration of the limestone specimens showed an overall increasing trend; moreover, at the beginning of the cycles, the physical deterioration of the specimen was significantly affected by the wetting-drying cycles, and at the end of the cycles, the physical deterioration of the specimen tended to be stable. The porosity deterioration degree reached 30.324% at the beginning of the cycles; there is a slight fluctuation in 20 cycles and then decreases as the number of cycles increases. The growth rate of water absorption increases slowly in 5~15 cycles and reaches the peak value in 20 cycles, and the growth rate decreases rapidly in the latter stages of the cycles. The increase rate of mass deterioration degree decreases with the increase of cycle number, the maximum average value can reach 61.887% at the beginning of cycles and is relatively stable at 20~25 cycles, and the average value at the end of cycle is obviously reduced by 3.167%. The nuclear magnetic resonance (NMR) test shows that the number and size of pores in the rock gradually increase with the increase of the number of wetting-drying cycles, and the wetting-drying cycles aggravate the internal damage of the rock. The number of shear cracks and fragmentation of the specimens increase as the increase of the number of cycles, and the failure of the specimens is mainly in the form of shear damage in the uniaxial compression test.
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Al Zubaydi, Abdulrahman H. T. "Effect of Wetting and Drying Cycles on Swell/Collapse Behavior and Cracks of Fine – Grained Soils." Tikrit Journal of Engineering Sciences 18, no. 4 (December 31, 2011): 71–79. http://dx.doi.org/10.25130/tjes.18.4.08.
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Many of the soils undergo volumetric changes due to the change in the water content. Swell-shrink and collapse behavior of those soils affects the stress state in soil and the interacted structures. Shrinkage in the soil produce cracks of different patterns, and affects the swelling potential in next wetting cycle.This study covers swelling and collapsing properties of four different soils from Mosul city. The changes in swelling and collapsing properties with respect to number of wetting and drying cycles have been investigated. Also, A shrinkage cracks have been studied with aid of digital image after each drying cycle. Number of segments and area of cracks calculated with aid of AutoCAD package.Results indicated that, the collapse potential is influenced by soil type (soil composition) and applied loads. As the applied loads increase the collapse potential increases. For sandy soil the collapse potential decreased with increasing wetting and drying cycles, and for the clayey soils, swell potential decreased while collapse potential increased with these cycles. It has been shown that the cracks increase with wetting-drying cycles. Larger values of percent crack area to the initial sample area has been observed in the soil that contain more clay content than other types of soils.
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Al-Jeznawi, Duaa, Marcelo Sanchez, and Abbas J. Al-Taie. "Effect of Wetting-Drying Cycles on Desiccation Crack Pattern and Soil Behavior." Key Engineering Materials 857 (August 2020): 188–94. http://dx.doi.org/10.4028/www.scientific.net/kem.857.188.
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Cracking, shrinkage, and curling of soils, in general, take place due to drying. These deformations lead to many problems include the development of main paths for water flow and pollutant transport, reduction of soil strength (and impact on other mechanical properties of soils), erosion in slopes, landslides, increase infiltration capacity of the soil and the differential settlement problems. Few studies have investigated the effect of wetting-drying (W-D) cycles on desiccation cracks of soils. The effect of multiple wetting-drying cycles in the cracking behavior was investigated in this research by performing several wetting-drying (W-D) cycles on the initially saturated samples (of pure kaolinite and a mixture of kaolinite with bentonite) under the lab atmosphere (24 ± 1 °C, and 52 ± 2% of RH). The weight of each sample was monitored using a computerized scale (with an accuracy of 0.01 g) connected to the computer. During the test, the water evaporation path with the development of surface cracks and volume shrinkage was monitored by means of digital images. It was observed that the crack patterns changed during the initial cycles, but there was an equilibrium state in the third and fourth W-D cycles. Additionally, it was observed that the main cracks formed in the first dry path were virtually closed after 10 minutes of the second wetting path; in the meantime, small cracks (fissures) were initiated after this wetting process. It was, also, detected that soils with high plasticity required more W-D cycles to reach the equilibrium condition than soils with low plasticity. The results of these experiments are useful for understanding the effect of different seasons on soil behavior.
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Li, Zhong Hua, Shu Rong Feng, and Chao Su. "Sulfate Resistance of Concrete under Restrained Condition." Advanced Materials Research 280 (July 2011): 67–70. http://dx.doi.org/10.4028/www.scientific.net/amr.280.67.
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Cracking due to shrinkage and restraint can accelerate corrosion of concrete resulted from harmful environment. Sulfate resistance of concrete under restrained condition was researched during drying and wetting cycles. The results showed that restraint can lead to controlled concrete cracking as result of shrinkage. It decreased sulfate corrosion resistance of concrete compared with free concrete. Due to 30% slag and 20% fly ash was added, surface cracking was avoided but scaling mass still higher than free concrete after drying and wetting cycles.
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James, Jijo, and Rajasekaran Saraswathy. "Performance of Fly Ash - Lime Stabilized Lateritic Soil Blocks Subjected to Alternate Cycles of Wetting and Drying." Civil and Environmental Engineering 16, no. 1 (June 1, 2020): 30–38. http://dx.doi.org/10.2478/cee-2020-0004.
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AbstractThe study investigated the durability performance of lime and fly ash stabilized lateritic soil blocks subjected to conditions of alternate wetting and drying. A locally available lateritic soil was collected and characterized in the laboratory for its geotechnical properties. The soil was then stabilized using lime and fly ash of various combinations. The blocks were tested for their compressive strength, water absorption and efflorescence. Durability was evaluated by subjecting the blocks to three cycles of wetting and drying and testing its compressive strength. The investigation revealed that fly ash-lime stabilization was capable of producing stabilized blocks meeting the standard requirements of Indian codes in terms of compressive strength, water absorption and efflorescence. The results revealed that a combination of 10 % fly ash with 10 % lime was enough to stabilize the soil to achieve the strength of a class 20 block whereas a combination of 10 % fly ash and 14 % lime was required to achieve the strength of a class 30 block. Wetting and drying cycles resulted in a marginal increase in strength after the first cycle but reduction thereafter. The optimal combination of 10 % fly ash and 14 % lime resulted in less than 25 % loss in strength after three cycles of wetting and drying.
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Xie, Hongxin, Qiangling Yao, Liqiang Yu, and Changhao Shan. "Study on Damage Characteristics of Water-Bearing Coal Samples under Cyclic Loading–Unloading." Sustainability 14, no. 14 (July 11, 2022): 8457. http://dx.doi.org/10.3390/su14148457.
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For underground water reservoirs in coal mines, the complex water-rich environment and changing overburden stress can damage coal pillar dams. In this paper, the coal samples from coal seam 22 of Shangwan coal mine were taken as research objects and the damage mechanism and characteristics of coal samples with different moisture content and wetting-drying cycles under cyclic loading were investigated. The results show that as the moisture content and wetting-drying cycles increase, the post-peak stage of the coal samples under cyclic stress becomes obvious, and the hysteresis loop changes from dense to sparse. Compared to the uniaxial compression experiment, when w = 5.28% (the critical water content), mechanical parameters such as peak strength and modulus of elasticity decrease the most. Under cyclic loading, the damage mode of both sets of coal samples was tensile damage, but the increase in wetting-drying cycles promotes the development of shear fractures. For evaluating fracture types, the RA-AF density map is more applicable to wetting-drying cycle coal samples, whereas for the coal samples with different moisture contents this should be carried out with caution. This study can provide some theoretical basis for the stability evaluation of coal pillar dams in underground water reservoirs.
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Qi, Ji, Daniel Markewitz, Maryam Foroughi, Eric Jokela, Brian Strahm, and Jason Vogel. "Drying-Wetting Cycles: Effect on Deep Soil Carbon." Soil Systems 2, no. 1 (January 9, 2018): 3. http://dx.doi.org/10.3390/soils2010003.
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Song, Yang, Qier Wu, Franck Agostini, Frédéric Skoczylas, and Xavier Bourbon. "Concrete shrinkage and creep under drying/wetting cycles." Cement and Concrete Research 140 (February 2021): 106308. http://dx.doi.org/10.1016/j.cemconres.2020.106308.
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Dong, Jun-gui, Hai-bo Lv, and Guo-yuan Xu. "Water State of Soil Experienced Wetting–Drying Cycles." Indian Geotechnical Journal 50, no. 6 (July 20, 2020): 1041–47. http://dx.doi.org/10.1007/s40098-020-00429-z.
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Dohnalová, Lenka, Petr Havlásek, and Vít Šmilauer. "Behavior of predried mature concrete beams subject to partial wetting and drying cycles." Acta Polytechnica CTU Proceedings 34 (March 24, 2022): 1–5. http://dx.doi.org/10.14311/app.2022.34.0001.
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The presented research focuses on the behavior of predried concrete beams with 2.5 m span subjected to cycles of nonsymmetric wetting and drying. Wetting is induced by partially immersing the specimens in a water basin. The submerged portion of the specimens was relatively low (1/5 to 1/10 of their height) leading to a highly nonuniform and nonsymmetric distribution of eigenstrains due to concrete swelling. Unlike conventional experiments on the volume changes of concrete, the measured quantity is not the axial deformation but the vertical displacement instead. This paper presents the experimental data obtained within two wetting and drying cycles, running over 1 year.
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Stefanidou, Maria, Eirini-Chrysanthi Tsardaka, and Aspasia Karozou. "The Influence of Curing Regimes in Self-Healing of Nano-Modified Cement Pastes." Materials 13, no. 22 (November 23, 2020): 5301. http://dx.doi.org/10.3390/ma13225301.
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The present study proposes nano-calcium oxide (NC) and nano-silica (NS) particles as healing agents in cement pastes, taking into account the curing conditions. Two series of specimens were treated in water and under wetting-drying cycles. The addition of NC (1.5%wt of binder) triggered early healing since cracks were healed within 14 days in underwater immersion and before 28 days at wetting-drying cycles. Attenuated Total Reflectance (ATR) spectroscopy and SEM analysis revealed that the healing products were mainly aragonite and calcite in water conditions and more amorphous carbonates under wetting-drying cycles. The combination of NS and NC (3.0%wt in total) offered healing under both curing conditions before 28 days. The presence of NS assisted toward porosity refinement and NC increased the carbonates’ content. The newly formed material was dense, and its elemental analysis by SEM revealed the C-S-H compounds that were also verified by ATR.
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Lu, Tianhui, Yuhan Wang, Hansong Zhu, Xiaorong Wei, and Mingan Shao. "Drying-wetting cycles consistently increase net nitrogen mineralization in 25 agricultural soils across intensity and number of drying-wetting cycles." Science of The Total Environment 710 (March 2020): 135574. http://dx.doi.org/10.1016/j.scitotenv.2019.135574.
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Zeng, Zhao Tian, Hai Bo Lu, and Yan Lin Zhao. "Wetting-Drying Effect of Expansive Soils and its Influence on Slope Stability." Applied Mechanics and Materials 170-173 (May 2012): 889–93. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.889.
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The wetting-drying effect of expansive soils plays an important role in slope stability analysis. According to the depth of atmospheric effect and the field observation data of moisture content, laboratory experiments on the strength of expansive soil with two wetting-drying cycle amplitudes were performed to discuss on the wetting-drying effect of expansive soil. The results show that the shear strength of expansive soil decreases with increasing number of cycles and finally reaches to a constant state. The value and cycle number of the constant state reduce with increase of amplitude of variation of water content. Furthermore, the stability analysis of expansive soil slope is studied with considering the wetting-drying effect. The results may provide the reference for the parameter selection in slope design.
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Zhou, Yu, Guoyu Li, Wei Ma, Dun Chen, Fei Wang, Yuncheng Mao, Qingsong Du, Jun Zhang, and Liyun Tang. "Experimental Study on Electric Resistivity Characteristics of Compacted Loess under Different Loads and Drying-Wetting Cycles." Advances in Civil Engineering 2021 (January 28, 2021): 1–12. http://dx.doi.org/10.1155/2021/6672430.
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Densely compacted loess foundations of many man-made infrastructures are often exposed to various loads and extreme weathering processes (e.g., drying-wetting cycles), which significantly deteriorate their mechanical properties. Traditional methods applied to characterize soil engineering properties are primarily based on visual inspections, point sensors, or destructive approaches, the results of which often have relatively high costs and cannot provide large-area coverage. The electrical resistivity method is a reasonable alternative that provides a nondestructive, sensitive, and continuous evaluation of the soil physical properties. Thus, the relationships between electrical resistivity and soil strength should be understood, particularly for scenarios in which soils undergo significant loads and cycles of drying and wetting. In this study, a suite of laboratory tests simulating loads (consolidation tests, unconfined compression tests, and uniaxial cyclic unloading-reloading tests) and seasonal field conditions (drying-wetting cycle tests) were conducted to quantitatively assess their deterioration effects on the geophysical and geotechnical properties of compacted loess. The experimental results indicated that electric resistivity decreases with the increase in stress and then approaches a stable value after the stress becomes 200 kPa. During the uniaxial compression process, the electric resistivity corresponds to both the stress and strain of loess in real-time. The electrical resistivity of loess reflects plastic damage under uniaxial unloading-reloading tests, but it is deficient in representing the dissipated energy of loess. The electrical resistivity of loess samples increases as the number of drying-wetting cycles increases but decreases with increasing cycle numbers after stabilization under consolidation load. The electrical resistivity can effectively characterize the mechanical and deformation characteristics of loess samples under loads and drying-wetting cycles, exhibiting a certain potential for long-term monitoring of soil engineering properties.
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Zha, Fusheng, Fanghua Zhu, Bo Kang, Long Xu, Yongfeng Deng, Chengbin Yang, and Chengfu Chu. "Experimental Investigation of Cement/Soda Residue for Solidification/Stabilization of Cr-Contaminated Soils." Advances in Civil Engineering 2020 (July 25, 2020): 1–13. http://dx.doi.org/10.1155/2020/8890149.
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Adopting more efficient and sustainable remediation materials is of great importance for the development of solidification and stabilization (S/S) technology. Among them, soda residue could be considered as a desirable binder due to its strong adsorption for heavy metals. For understanding of the performance of Cr-contaminated soils treated by cement/soda residue, the strength, leaching and microstructural characteristics, and the long-term effectiveness under wetting-drying cycles were comprehensively investigated in this study. The results showed that the unconfined compressive strength (UCS) increased and the leached Cr3+ concentration decreased with curing time, binder content, and binder ratio. Increasing the soda residue from C6S14 to C6S24 could improve soil strength and reduce leachability of Cr3+, while a reverse trend was presented with increasing initial Cr3+ concentration. With subsequent wetting-drying cycles, the UCS further increased and then decreased; inversely, the leached Cr3+ decreased, followed by an increase of Cr-contaminated soils. For the specimens of C6S14 and C6S24, the maximum UCS of 6.04 MPa and 6.48 MPa was reached; correspondingly, the minimum leached Cr3+ concentration of 2.78 mg/L and 1.93 mg/L was reached after 3 wetting-drying cycles, respectively. Microstructure analysis results found that reaction products like calcium silicate hydrate (C-S-H) and ettringite (AFt) increasingly occupied the soil pore space and caused a denser soil structure after 3 wetting-drying cycles, which indicated the long-term effectiveness of contaminated soils treated by cement/soda residue.
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Zhang, Chen, Zheng-yin Cai, Ying-hao Huang, and Hao Chen. "Laboratory and Centrifuge Model Tests on Influence of Swelling Rock with Drying-Wetting Cycles on Stability of Canal Slope." Advances in Civil Engineering 2018 (December 20, 2018): 1–10. http://dx.doi.org/10.1155/2018/4785960.
Full textAbstract:
This study focused on the swelling behavior of swelling rock from canal basement under multiple drying-wetting (D-W) cycles. A series of laboratory tests were conducted on a swelling rock, with the cracking and strength behaviors investigated. By using image-processing technique, the crack patterns were described, and then quantitatively analyzed on the basis of the fractal dimension. The experimental data indicated that swelling ability, including cracking level, fractal dimension, and strength, decrease with increasing drying and wetting cycle. On this basis, a series of centrifuge model simulations for simulating slope failure by drying-wetting cycles were performed, where the drying process was achieved by heat bulbs. The monitoring results suggested that a global slope failure has occurred after total cycle of 4th corresponding to 4 years. Due to the development of surface cracking, the infiltration in the slope was severe and nonuniform in space and time. Meanwhile, the failure mechanism of soft rock slope induced by D-W was discussed.
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Kamaruddin, Fatin Amirah, Vivi Anggraini, Bujang Kim Huat, and Haslinda Nahazanan. "Wetting/Drying Behavior of Lime and Alkaline Activation Stabilized Marine Clay Reinforced with Modified Coir Fiber." Materials 13, no. 12 (June 17, 2020): 2753. http://dx.doi.org/10.3390/ma13122753.
Full textAbstract:
The durability of natural and treated clay soil stabilized with lime and alkaline activation (AA) affected by environmental factors (hot and humid) was determined in this study. Investigation and evaluation on the strength of the soil, moisture content, and volume change of the specimen were determined at each curing period (7, 28, and 90 days) based on the weather conditions. An unconfined compressive strength (UCS) of the specimen at three different wetting/drying cycles (one, three, and five cycles) was determined. The findings show that the strength of the treated specimens fluctuated with increment and decrement strength (one and three cycles) in the range of 1.41 to 1.88 MPa (lime) and 2.64 to 8.29 MPa (AA), while for five cycles with a curing period of 90 days the decrement was in the range of 1.62 to 1.25 MPa and 6.06 to 5.89 MPa for lime and AA, respectively. The decrement percentage for treated samples that were subjected to five cycles of wetting and drying in 90 days was found to be 20.38% (lime) and 38.64% (AA), respectively. Therefore, it can be summarized that wetting/drying cycles have a significant influence on the durability, strength, and the volume changes of the specimens.
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Kay, BD, and AR Dexter. "The influence of dispersible clay and wetting/drying cycles on the tensile strength of a red-brown earth." Soil Research 30, no. 3 (1992): 297. http://dx.doi.org/10.1071/sr9920297.
Full textAbstract:
The tensile strength of aggregates is a dynamic property under field conditions and for any given soil reflects the integration of processes leading to a strengthening and weakening of failure zones. The objectives of this study were to determine if variation in the tensile strength of natural aggregates from a red-brown earth could be related to the combined effects of (a) conditions favouring dispersion of clay and a subsequent increase in strength by cementation on drying and (b) wetting/drying cycles which would result in a decrease in strength. Aggregates were collected from the A horizon of different long-term rotations. The seasonal variation in tensile strength was assessed using data collected in 1988 and unpublished data which had been collected annually between 1978 and 1981. Trends in tensile strength over 5 years confirmed the importance of an interaction between climatic conditions which could lead to increased dispersion of clay and wetting/drying cycles. The extent of weakening of failure zones by wetting/drying cycles varied with the rotation. The nature of the impact of cropping history on tensile strength was dependent on antecedent climatic conditions.
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Li, Wei, Liming Yi, Wen Jiang, Hua Dong, and Yong Zhang. "Effects of Ultrafine Blast Furnace Slag on the Microstructure and Chloride Transport in Cementitious Systems under Cyclic Drying–Wetting Conditions." Applied Sciences 12, no. 8 (April 18, 2022): 4064. http://dx.doi.org/10.3390/app12084064.
Full textAbstract:
This paper presents experimental investigations into the effects of ultrafine blast furnace slag on microstructure improvements against chloride penetration in saturated and unsaturated cementitious systems exposed to cyclic drying–wetting conditions. The hydration kinetics of ultrafine slag powders and pore solution chemistry in slag-blended cementitious systems at different ages, together with the main hydration products and pore structure characteristics, were determined. The chloride profiles accounting for different slag contents and drying–wetting cycles were measured. The results reveal that the reactivity of ultrafine slag can be well described with Avrami’s equation. The dilution effect of the slag predominated the pore solution chemistry, and the pH value decreased with a higher inclusion of slag. An optimal inclusion of 65% slag by mass of the binder corresponding to the finest pore structure and highest hydrotalcite content was found, which provides a reasonable basis for the slow chloride diffusion and high chloride binding. Under drying–wetting exposure, the specimen with a lower saturation exhibited a higher chloride transport caused by capillary absorption in the skin layer. The chloride transport tended to be diffusion controlled after sufficient drying–wetting cycles.