Journal articles: 'Wetting-induced collapse'

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Ng, C. W. W., Q. Cheng, and C. Zhou. "Thermal effects on yielding and wetting-induced collapse of recompacted and intact loess." Canadian Geotechnical Journal 55, no. 8 (August 2018): 1095–103. http://dx.doi.org/10.1139/cgj-2017-0332.

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Yielding and wetting-induced collapse are two important interrelated aspects of unsaturated loess behaviour. Previous studies on loess were generally conducted under a single temperature condition. The principal objective of this study is to investigate thermal effects on yielding and wetting-induced collapse of recompacted and intact loess. Isotropic compression tests were carried out to determine yield stress at different suctions (0 and 100 kPa) and temperatures (5, 23, and 50 °C). Moreover, wetting tests were conducted at various temperatures and stresses. Results of the wetting tests were interpreted using the measured yield stress at various suctions and temperatures. It is found that yield stress decreases with decreasing suction (wetting-induced softening). The wetting-induced softening of recompacted loess is more significant at a higher temperature. The observed thermal effects on wetting-induced softening are likely because with decreasing suction, the stabilizing interparticle normal force decreases more at a higher temperature. In contrast, when the applied stress reaches the yield stress during wetting, yielding and plastic volumetric contraction can be observed. More importantly, wetting-induced contraction of recompacted loess at 50 °C is about three times of that at 5 °C. The larger contraction at 50 °C is mainly because the wetting-induced softening is larger at a higher temperature.

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Jiang, Mingjing, Haijun Hu, and Fang Liu. "Summary of collapsible behaviour of artificially structured loess in oedometer and triaxial wetting tests." Canadian Geotechnical Journal 49, no. 10 (October 2012): 1147–57. http://dx.doi.org/10.1139/t2012-075.

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This paper summarizes experimental studies on wetting-induced collapsibility in loess using single-oedometer, double-oedometer, and triaxial wetting tests. Artificially structural loess samples with interparticle bonding calcite (CaCO3) and a large void ratio were tested in the laboratory to avoid sampling disturbance of natural loess. The comparison between the single- and double-oedometer tests confirms that the wetting-induced deformation is independent of the sequence of wetting and loading. The conventional triaxial apparatus was enhanced for investigating the collapse deformation in response to different water content increments when subjected to different stress levels. The wetting-induced strain subjected to high confining pressure develops in two steps. It increases with increasing water content and reaches a relatively stable plateau, and then increases rapidly again until a final stable state is reached. The initial collapse surface was found by plotting the wetting-induced strain vectors observed in triaxial wetting tests. The wetting-induced strain is negligible when a specimen is wetted at a stress point inside this surface, while it becomes significant when wetted beyond this surface.

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Vrancken, Nandi, Guy Vereecke, Stef Bal, Stefanie Sergeant, Geert Doumen, Frank Holsteyns, Herman Terryn, Stefan de Gendt, and Xiu Mei Xu. "Pattern Collapse of High-Aspect-Ratio Silicon Nanostructures - A Parametric Study." Solid State Phenomena 255 (September 2016): 136–40. http://dx.doi.org/10.4028/www.scientific.net/ssp.255.136.

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This work focuses on capillary-induced collapse of high-aspect-ratio silicon nanopillars. Modification of the surface chemistry is demonstrated to be an efficient approach for reducing capillary forces and consequently reduce pattern collapse. Special effort is spent on determination of the wetting state of chemically modified surfaces as complete structure wetting is of utmost importance in wet processing. In light of this, an ATR-FTIR based method has been developed to unambiguously distinguish between wetting and non-wetting states.

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Capobianco, Vittoria, Leonardo Cascini, Sabatino Cuomo, and Vito Foresta. "Wetting-induced collapse behaviour of a natural and vegetated coarse pyroclastic soil." E3S Web of Conferences 195 (2020): 03025. http://dx.doi.org/10.1051/e3sconf/202019503025.

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Unsaturated pyroclastic soils originated by Vesuvius volcano show a collapsible behaviour upon wetting with a significant reduction in volume and rearrangement of solid skeleton. The paper investigates the role played by vegetation on wetting-induced collapse behaviour (namely, collapsibility) of reconstituted unsaturated soil specimens through two series of wetting tests in a standard oedometer. The first series of tests was performed on bare soil specimens, as to resemble the site conditions. The second group of tests was conducted on the same soil previously vegetated for 20 weeks with perennial graminae species, which are frequently used as a nature-based solution for contrasting surface erosion along slopes in different geo-environmental contexts. First, an initial small vertical net stress was applied on partially saturated specimens having similar initial saturation degree, then collapse was induced by flooding the specimens with distilled water and final vertical displacements were measured. As main outcome, soil porosity is highly reduced by the growth of grass roots. Consequently, the potential wetting collapse in the rooted soils is inhibited by low values of porosity. For similar initial soil porosity, in both bare and vegetated specimens (after root growth), a further reduction of the volumetric collapse magnitude is observed.

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Kamei, Takeshi, and Masao Enomoto. "Wetting-Induced Collapse Behaviour of Compacted Silty Soil." Doboku Gakkai Ronbunshu, no. 505 (1994): 97–103. http://dx.doi.org/10.2208/jscej.1994.505_97.

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Lawton, Evert C., Richard J. Fragaszy, and Mark D. Hetherington. "Review of Wetting‐Induced Collapse in Compacted Soil." Journal of Geotechnical Engineering 118, no. 9 (September 1992): 1376–94. http://dx.doi.org/10.1061/(asce)0733-9410(1992)118:9(1376).

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Fu, Zhong Zhi, Si Hong Liu, and Wei Xing Gu. "Evaluating the Wetting Induced Deformation of Rockfill Dams Using a Hypoplastic Constitutive Model." Advanced Materials Research 243-249 (May 2011): 4564–68. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.4564.

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Evaluating the wetting induced deformation of the shell is one of the most important issues in designing a high rockfill dam. Excessive wetting deformation and the relevant stress deterioration in adjacent impervious structures may cumber the normal operation of the engineering and seriously risk the safety of the dam. In this paper, a hypoplastic creep model is incorporated into a finite element procedure to study the wetting induced deformation of a rockfill dam. Considerable lateral movement towards the upstream and an additional wetting collapse presented in the upstream shell induced by reservoir impounding is effectively predicted by the finite element model. The reasonable results confirm the feasibility of applying the hypoplastic model to the evaluation of the wetting induced deformation in dam engineering.

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Liu, Qiqi, Wanli Xie, Hui Yang, Kangze Yuan, Siyu Zhang, Xinyu Li, Pengxin Qu, Zhiyi Wu, Jiahao Zhou, and Xuanyu Gao. "Intrinsic Mechanisms of Differences in Wetting-Induced Deformation of Soils on Chinese Loess Plateau: Insights into Land Stability and Sustainable Management." Land 14, no. 2 (February 3, 2025): 312. https://doi.org/10.3390/land14020312.

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Wetting-induced soil deformation significantly impacts land stability and management on the Chinese Loess Plateau. This study analyzed silt soils from the Late Pleistocene (1 m depth) and Middle Pleistocene (25 m depth) to investigate compression and collapsible deformation during wetting. The compression in both soils progressed through three stages: slow deformation under low pressure, accelerated deformation under moderate pressure, and decelerated deformation under high pressure. Wetting intensified the compression in the 1 m sample but reduced it in the 25 m sample, with the deformation becoming more sensitive to the initial water content under higher pressures. Collapse tests showed contrasting behaviors: the 1 m sample exhibited collapsibility, while the 25 m sample displayed expansiveness (a negative collapsibility coefficient). Microstructural analysis revealed that the 1 m sample with abundant macropores and overhead structures had a lower structural stability than the 25 sample with more stable, rounded micropores. The wetting-induced deformation was governed by the balance between clay mineral expansion and structural collapse, with collapsibility prevailing when collapse dominated and expansiveness prevailing when expansion was predominant. These findings provide valuable insights into soil–water interactions and support improved land use and management strategies in the loess region.

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Choudhury, Chinumani, and Tadikonda Venkata Bharat. "Wetting-induced collapse behavior of kaolinite: influence of fabric and inundation pressure." Canadian Geotechnical Journal 55, no. 7 (July 2018): 956–67. http://dx.doi.org/10.1139/cgj-2017-0297.

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Collapsible soils are known to withstand high normal stresses without undergoing a significant volume change in an air-dry state. The soil is, however, susceptible to a large volume change upon wetting. The volumetric collapse behavior of these soils is of great engineering interest to address the problem of ground subsidence. Kaolinite was found to be a collapsible soil similar to the loess soil. The collapse mechanism in kaolinite was due to changes in particle association (fabric) with the interaction with different pore fluids. Several physicochemical parameters strongly influenced the particle association by altering the charges on the particle surfaces and edges. The collapse nature of the kaolinite was investigated with great detail in this work. Wetting-induced collapse behavior of kaolinite was studied under the influence of pore-fluid chemistry using a multi-scale approach. The influence of pH, salt concentration, and dielectric pore-fluid environment on the clay behavior was analyzed using sedimentation and collapse tests. The collapse test results were well corroborated with the sedimentation test data, scanning electron microscopy images of lyophilized specimens, and edge isoelectric point (IEPedge). The influence of inundation fluid and inundation pressure on the fabric changes and collapse potential was elucidated. The collapse potential was found to depend on the inundation pressure and pore-fluid characteristics. Maximum collapse potential was observed to be due to water inundation and minimum due to inundation with kerosene. The mechanical pressure at higher inundation pressures helped to bring the clay platelets into better face–face association during the inundation.

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THOREL, L., V. FERBER, B. CAICEDO, and I. M. KHOKHAR. "Physical modelling of wetting-induced collapse in embankment base." Géotechnique 61, no. 5 (May 2011): 409–20. http://dx.doi.org/10.1680/geot.10.p.029.

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Sulaiman, Hadeel SA, Muayad A. Al-Sharrad, and Idham A. Abed. "Reduction of the Wetting Collapse of Sandy Gypseous Soil by Using Microbial-Induced Calcite Precipitation." Salud, Ciencia y Tecnología - Serie de Conferencias 3 (June 2, 2024): 817. http://dx.doi.org/10.56294/sctconf2024817.

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Microbial-induced carbonate precipitation (MICP) is a promising technology for cementing sandy soils, improving ground, repairing concrete cracks, and remediating contaminated land. The aim of this research is to implement this technology in mitigating wetting collapse of Ramadi sandy gypseous soil which has a gypsum content of about 35%. To achieve this aim, the urease-producing bacterial strain Bacillus Megaterium SI was used and treated soil specimens were prepared. The preliminary results showed a well-defined bacterium activity with a precipitated calcite of 13-16.5% by the end of the first week. The results of the collapsibility test showed that increasing cementation solution molarity from 0.25M to 1M lowered the wetting strain and total strain caused by both loading to 100 kPa and wetting by about 75%. Therefore, the MICP demonstrates the potential to mitigate the wetting collapse of the sandy gypseous soil despite its high gypsum content.

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12

Ge, M., J. Pineda, and D. Sheng. "The competing effects of wetting and volume change on G₀ in compacted loess." Géotechnique Letters 13, no. 4 (December 1, 2023): 1–21. http://dx.doi.org/10.1680/jgele.22.00125.

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This paper explores the relative contributions of wetting (suction reduction) and its associated volume change on the small-strain shear stiffness, G0,in compacted loess from Xi'an, China. Results from one-dimensional compression tests with measurements of the shear wave velocity upon wetting and loading paths are presented. The experimental results show that the softening caused by wetting compete with the densification caused by plastic deformation and their effects on G0 are strongly controlled by stress level applied prior to wetting. Below the compaction stress, suction effects are dominant and G0 reduces irrespective of the magnitude of the collapse strain. With the increase in the stress level, the reduction in G0 caused by saturation is compensated by the plastic deformation triggered by soil collapse. This behaviour is clearly observed when the soil is first loaded to the compaction stress, where the maximum collapse strain is measured upon wetting. Volume change is dominant once the compaction stress is exceeded so that G0 tends to increase upon wetting. A wetting-induced stiffness factor D is defined to demonstrate that the change in G0 varies linearly with the stress level and this behaviour is independent of the compaction conditions. The contributions of soil suction and void ratio on G0 is explored using expressions available in the literature which are then used to propose a new definition for the stiffness factor D.

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13

Ge, Miaomiao, Jubert A. Pineda, Daichao Sheng, Glen J. Burton, and Ning Li. "Microstructural effects on the wetting-induced collapse in compacted loess." Computers and Geotechnics 138 (October 2021): 104359. http://dx.doi.org/10.1016/j.compgeo.2021.104359.

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14

Hou, Xiaokun, Sai K. Vanapalli, and Tonglu Li. "Wetting-induced collapse behavior associated with infiltration: A case study." Engineering Geology 258 (August 2019): 105146. http://dx.doi.org/10.1016/j.enggeo.2019.105146.

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15

Wen, Hua, Songyin Deng, Wei Zhang, Qiangong Cheng, Jiujiang Wu, and Dailin Hu. "A Simplified Approach to Estimating the Collapsible Behavior of Loess." Advances in Civil Engineering 2020 (December 10, 2020): 1–13. http://dx.doi.org/10.1155/2020/3712595.

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Due to the particularity and complexity of loess, it is challenging to estimate its collapsible behavior numerically at present. This paper aims to propose a simplified approach, which is named as the modulus reduction method, to estimate the collapsible behavior of loess. For loess upon wetting, the modulus reduction method assumes that loess collapses as a result of strength reduction due to the additional stress induced by increasing bulk density. Thus, special attention is given to the confirmation and determination approaches of bulk density and deformation modulus of loess upon wetting. Subsequently, a comparative numerical analysis based on the modulus reduction method and the force-water equivalent method, which is commonly used for the analysis of negative skin friction on piles in collapsible soil, is investigated. It turns out that the result obtained by the modulus reduction method is more consistent with the collapse mechanism of loess compared with that derived by the force-water equivalent method. Finally, a case history concerning a published field test of loess upon wetting is studied, and the result shows that the simulated deformation characteristics by adopting the modulus reduction method agree excellently well with the measured data. The case study validates that the modulus reduction method is feasible to analyze the collapse of loess and suitable for the numerical simulation involving collapsible loess.

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Liu, Zhen, Fengyin Liu, Fuli Ma, Mei Wang, Xiaohong Bai, Yonglai Zheng, Hang Yin, and Guoping Zhang. "Collapsibility, composition, and microstructure of loess in China." Canadian Geotechnical Journal 53, no. 4 (April 2016): 673–86. http://dx.doi.org/10.1139/cgj-2015-0285.

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The collapse potential, mineralogy, microstructure, and particle morphology of a loess from the Loess Plateau, China, were characterized by double oedometer testing, X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and image analysis to elucidate the origin of its collapse behavior. Results show that the loess is highly collapsible with a maximum collapse index of 6.7% at a vertical stress of ∼200 kPa. The deposit contains both nonclay (i.e., quartz, albite, muscovite, and calcite) and clay (i.e., two chlorites) minerals. Microstructural, chemical, and image analyses indicate that interparticle calcite and clay cementation and silt particle morphology render the intact soil a metastable structure. Wetting-induced collapse is attributed to both primary and secondary microstructure features. The former is the abundance of weakly cemented, unsaturated, porous pure clay and clay–silt mixture aggregates whose slaking upon wetting initiates the overall structural collapse, while the latter consists of high porosity, unstable particle contacts, and clay coating on silt particles that act synergistically to augment the collapse. A conceptual microstructural model of a four-tiered hierarchy (i.e., primary clay and silt particles, clay aggregates and clay-coated silt particles, clay–silt mixture aggregates, and cemented aggregate matrix) is proposed to represent its structural characteristics and to account for its high collapsibility.

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Vilar, Orencio Monje, and Roger Augusto Rodrigues. "Collapse behavior of soil in a Brazilian region affected by a rising water table." Canadian Geotechnical Journal 48, no. 2 (February 2011): 226–33. http://dx.doi.org/10.1139/t10-065.

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Collapsible soils are usually nonsaturated, low density, and metastable-structured soils that are known to exhibit a volume reduction following an episode of moisture increase or suction reduction. This paper describes the collapsible behavior of clayey sand based on controlled soil suction tests carried out on undisturbed samples from the city of Pereira Barreto, in the State of São Paulo, Brazil. Foundation settlements due to soil collapse are common in this region and occurred during the filling of the reservoir of the Três Irmãos Dam, which induced the elevation of the groundwater table in different parts of Pereira Barreto. This paper shows that collapse strains depend on the stress and soil suction acting in the sample and that saturation is not necessary for a collapse to occur. The influence of soil suction, gradual wetting, and the wetting and drying cycle on the collapsible behavior of the soil is also shown and discussed.

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Weng, Xiaolin, Yufeng Sun, Yuwei Zhang, Haoshuang Niu, Xi Liu, and Yuelin Dong. "Physical modeling of wetting-induced collapse of shield tunneling in loess strata." Tunnelling and Underground Space Technology 90 (August 2019): 208–19. http://dx.doi.org/10.1016/j.tust.2019.05.004.

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Nachum, Shay, Mark Talesnick, and Sam Frydman. "Effect of external hydraulic head on swelling of unsaturated clay." E3S Web of Conferences 195 (2020): 03035. http://dx.doi.org/10.1051/e3sconf/202019503035.

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Laboratory testing of the one-dimensional swell of soil (usually unsaturated clay) is generally performed according to ASTM standard D4546. The standard procedure requires that “the specimen is inundated with test water and the one-dimensional wetting-induced swell or collapse strain is measured”. This procedure undoubtedly provides an upper limit to the swell which may be expected under field conditions, and may be relevant to cases in which low lying areas are expected to be inundated as a result of a wetting episode. However, in other cases, wetting of the soil may result from less extreme conditions - for example absorption of water from underlying, wetted layers, or soaking of the lower portion of a swelling layer and resultant upward wetting due to suction forces. The present paper describes a laboratory investigation of the effect of external hydraulic head on swell. The results demonstrate the importance of applying test conditions consistent with those expected in the field situation.

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Xie, Wan-Li, Ping Li, Sai K. Vanapalli, and Jia-Ding Wang. "Prediction of the wetting-induced collapse behaviour using the soil-water characteristic curve." Journal of Asian Earth Sciences 151 (January 2018): 259–68. http://dx.doi.org/10.1016/j.jseaes.2017.11.009.

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Ng, Charles Wang Wai, Hamed Sadeghi, S. K. Belal Hossen, C. F. Chiu, Eduardo E. Alonso, and Sina Baghbanrezvan. "Water retention and volumetric characteristics of intact and re-compacted loess." Canadian Geotechnical Journal 53, no. 8 (August 2016): 1258–69. http://dx.doi.org/10.1139/cgj-2015-0364.

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A laboratory testing program was conducted to investigate the effects of microstructure on the water retention curve (WRC) and wetting–drying induced volume change in loess. The axis translation and vapor equilibrium techniques were adopted to control suction in the range of 0–400 kPa and 4–140 MPa, respectively. Hysteresis in the WRC of loess was observed for the entire range of suction studied. Compared to re-compacted loess, intact loess exhibits a more pronounced hysteresis in the suction range below 20 kPa, which can be explained by the ink-bottle pore neck effect or constricted pores. The hypothesis is supported by microstructural evidence of mercury intrusion porosimetry and scanning electron microscopy tests. However, re-compacted loess exhibits larger hysteresis than intact loess for suctions above 30 kPa. A conceptual model was introduced, which links WRC to the corresponding pore-size density (PSD) function. Regarding volume change, more noticeable drying-induced shrinkage, but yielding at a lower suction, was observed for re-compacted loess. This is consistent with the compression test results. Stress has a significant effect on change of PSD and constricted macropores leading to a shift in the main wetting curve and a less pronounced hysteresis. Intact loess exhibits a stress-dependent wetting-induced collapse and drying-induced shrinkage.

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Xiao, Qinghua, Shengxiang Lei, Kai Cui, Wensheng Li, Xiangyu Han, Jianguo Liu, Xunhong Huang, and Shougen Chen. "Effect of the longitudinal local wetting-induced collapse on tunnel structure in loess strata." Tunnelling and Underground Space Technology 122 (April 2022): 104361. http://dx.doi.org/10.1016/j.tust.2022.104361.

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23

Jiang, Mingjing, Tao Li, Colin Thornton, and Haijun Hu. "Wetting-Induced Collapse Behavior of Unsaturated and Structural Loess under Biaxial Tests Using Distinct Element Method." International Journal of Geomechanics 17, no. 1 (January 2017): 06016010. http://dx.doi.org/10.1061/(asce)gm.1943-5622.0000693.

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Jones, G. S., C. M. Cooling, M. M. R. Williams, and M. D. Eaton. "Wetting-induced volumetric collapse of UO2 powder beds and the consequence on transient nuclear criticality excursions." Progress in Nuclear Energy 154 (December 2022): 104460. http://dx.doi.org/10.1016/j.pnucene.2022.104460.

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Rotisciani, G. M., F. Casini, A. Desideri, and G. Sciarra. "Hydromechanical behavior of an embankment during inundation." Canadian Geotechnical Journal 54, no. 3 (March 2017): 348–58. http://dx.doi.org/10.1139/cgj-2016-0174.

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The paper presents a comprehensive analysis of the hydromechanical response of an embankment subject to inundation. The modified Cam clay model extended to unsaturated conditions and formulated in terms of Bishop’s effective stress is used to predict the mechanical behavior of the sand–clay mixture. The model’s ability to accurately reproduce the embankment response is evaluated by comparing the numerical predictions with the results of the physical model. Time evolution and spatial distribution of the wetting-induced displacements are analyzed together with the stress paths resulting from the imbibition process. The influence of after-compaction conditions on the embankment performance is examined focusing on the occurrence of the volumetric collapse.

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Coyne, Lelia M., Patricia M. Costanzo, and B. K. G. Theng. "Luminescence and ESR studies of relationships between O−-centres and structural iron in natural and synthetically hydrated kaolinites." Clay Minerals 24, no. 4 (December 1989): 671–93. http://dx.doi.org/10.1180/claymin.1989.024.4.09.

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AbstractLuminescence, induced by dehydration and by wetting with hydrazine and unsymmetrically substituted hydrazine, and related ESR spectra have been observed from several kaolinites, synthetically hydrated kaolinites, and metahalloysites. The amine-wetting luminescence results suggest that intercalation, not a chemiluminescence reaction, is the luminescence trigger. Correlation between dehydration-induced luminescence and g = 2 ESR signals associated with O−-centres in several natural halloysites, and concurrent diminution of the intensity of both these signal types as a function of aging in two 8.4 Å synthetically hydrated kaolinites, confirm a previously-reported relationship between the luminescence induced by dehydration and in the presence of O−-centres (holes, i.e., electron vacancies) in the tetrahedral sheet. Furthermore, the ESR spectra of the 8.4 Å hydrate showed a concurrent change in the line shape of the g = 4 signal from a shape usually associated with structural Fe in an ordered kaolinite, to a simpler one typically observed in more disordered kaolinite, halloysite, and montmorillonite. Either structural Fe centres and the O−-centres interact, or both are subject to factors previously associated with degree of order. The results question the long-term stability of the 8.4 Å hydrate, although XRD does not indicate interlayer collapse over this period. Complex inter-relationships are shown between intercalation, stored energy, structural Fe, and the degree of hydration which may be reflected in catalytic as well as spectroscopic properties of the clays.

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Fatahizadeh, Marieh, and Hossein Nowamooz. "Settlement Foundations by Exploring the Collapse of Unsaturated Soils." Applied Sciences 14, no. 17 (August 30, 2024): 7688. http://dx.doi.org/10.3390/app14177688.

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Increasing extreme weather events and climate change can significantly affect soil moisture regimes, particularly soil suction, leading to additional challenges associated with unsaturated soils, including the collapse phenomenon. The collapsibility of soils poses significant engineering and geotechnical risks globally, necessitating urgent attention from engineers. This work establishes a numerical model of a shallow foundation subjected to rainfall and load using COMSOL Multiphysics. A hydromechanical model (H-M) is introduced which incorporates The Richards’ module and the Extended Basic Barcelona Model (EBBM) as a constitutive model to predict settlements in shallow foundations influenced by climate change and intense rainfall. The validation of the model is conducted through experimental tests, ensuring its accuracy. Additionally, in the practical application, the hydromechanical model is applied to anticipate the effect of infiltration on settlements of shallow foundations. The simulation results show that infiltration leads to an increase in the pressure head above the water table, decreasing soil suction, which induces additional settlement due to wetting-induced collapse. The maximum settlement happened at the corners of the footing due to increased exposure to infiltration and a greater reduction in suction. The collapse potential calculated from the numerical simulation was found to be consistent with the predictions established via analytical models, validating the accuracy of the numerical approach.

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Jawad, Hala Mahmood, and Zuhair Kadhim Jahanger. "Collapse Pattern in Gypseous Soil using Particle Image Velocimetry." IOP Conference Series: Earth and Environmental Science 1374, no. 1 (August 1, 2024): 012012. http://dx.doi.org/10.1088/1755-1315/1374/1/012012.

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Abstract Gypseous soil is prevalent in arid and semi-arid areas, is from collapsible soil, which contains the mineral gypsum, and has variable properties, including moisture-induced volume changes and solubility. Construction on these soils necessitates meticulous assessment and unique designs due to the possibility of foundation damage from soil collapse. The stability and durability of structures situated on gypseous soils necessitate close collaboration with specialists and careful, methodical preparation. It had not been done to find the pattern of failure in the micromechanical behavior of gypseous sandy soil through particle image velocity (PIV) analysis. This adopted recently in geotechnical engineering to track the motion of soil grains and using tracer particles by applying digital particle image analysis. It has also been used to study the displacement distribution in some cases of granular materials. Therefore, the goal of this study is to find out how gypseous sand medium moves when in contact with a rigid strip foundation that is under static stress and plane strain conditions. The experimental model would focus on two common types of wetting, namely water table rise and dry conditions. The PIV showed that the collapse pattern under the footing is of the type of punching shear failure. The predominant mechanism of soil deformation was the vertical compression of the gypseous granular soil. The results showed that understanding gypseous sandy grain displacement and failure patterns at the local scale is crucial for enhancing the design of foundations under static stress conditions.

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Beber, Raniero, Alessandro Tarantino, Matteo Pedrotti, and Rebecca Lunn. "The effect of clay water content in the Jet Erosion Test." E3S Web of Conferences 92 (2019): 02016. http://dx.doi.org/10.1051/e3sconf/20199202016.

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The understanding of the onset of breaching induced by surface erosion is fundamental to enable definition of the level of protection afforded by embankments and provision of standards for the design of new structures and the upgrading of existing ones. Compacted embankment materials are generally partially saturated due to seasonal variation in the water content. At the onset of the overflow process embankments undergo to a wetting process due to the changes at the outer surface boundary conditions (i.e. overflow). Erosion behaviour is known to be a counterbalance between gravity forces and shear erosion forces. However, as the particle size decreases (i.e. clayey soils), gravitational forces become negligible and electrochemical interaction between particles play a dominant role. Clay microstructure (e.g. particle configuration and inter-particle forces) changes with the hydro-mechanical stresses history. Thus, it is necessary to consider the microstructural changes in particle configuration to understand the influence of microstructure on the macroscopic behaviour of clay during erosion. Upon wetting, clay have a swelling/collapse behaviour. This research presents experimental results on erosion of clay samples compacted at the same initial dry density but with different compaction water content. The influence of different wetting times on erosion is also investigated. We show that for a given as-compacted water content, the longer the wetting stage, and hence the higher the sample water content, the more erodible the samples. Additionally, for samples compacted at the same dry density, the ones compacted on the dry side of optimum are more erodible than samples compacted at the optimum water content, despite the lower water content at formation. We hypothesise that this may be due to the formation of a different initial microstructure in sample on the dry side of optimum (i.e. bi-modal pore size distribution). Our results contribute to the fundamental understanding of time-dependent mechanisms that influence erosion of clay embankments during overflow and, hence, to embankment failure. In addition, these tests show how basic concepts of unsaturated soil mechanics can serve as a guide to ‘design’ the compaction conditions of embankment material.

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Li, Yexin, Gang Lv, Daohan Wang, Wenxuan Su, and Zhongping Wei. "Erosion Failure of Slope in a Dump with Ground Fissure under Heavy Rain." Water 14, no. 21 (October 28, 2022): 3425. http://dx.doi.org/10.3390/w14213425.

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The dump, with the compact rock platform and high and steep loose slope that is formed during coal mining, is the most serious area of soil erosion in a surface coal mine. Ground fissures are a typical geological hazard in coal mining areas. However, the effect of ground fissures on soil erosion remains unclear. Rainfall experiments were conducted to determine the varying characteristics of wetting front, runoff and sediment production, and soil denudation rate, as well as the effects of ground fissures on these factors in a platform-slope system of a dump. Ground fissures could significantly enhance wetting front and soil erosion. Rill erosion was formed as the rainfall and runoff flushed the soil, which eventually developed into erosion gullies. Erosion failure modes with platform-slope systems in the dump could be divided into the surface erosion stage, fissure deformation stage, rill erosion stage, fissure collapse-rapid increase stage, and stable stage. Runoff power and flow shear stress had the greater influence on soil denudation rate, which indicated that erosion energy of concentrated flow had important influence on soil erosion. Moreover, shallow mudflow induced by rainfall was one of the forms of soil slope instability; it occurred in a short time with great soil erosion. Soil erosion in the dump with ground fissures was mainly shallow mudflow and rill erosion, resulting from the combined effect of hydraulic erosion and gravity erosion.

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Noor, Sarah Tahsin. "Numerical and Analytical Modeling for Predicting Drag Load Induced on Pile in Collapsible Soil because of Inundation." Open Civil Engineering Journal 11, no. 1 (August 15, 2017): 664–75. http://dx.doi.org/10.2174/1874149501711010664.

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Introduction:Negative skin friction that develops on the pile surface when the soil (adjacent to the pile shaft) settles but the pile is in static condition, causes an additional load (known as drag load) induced on pile. Substantial settlement of collapsible soil occurs only because of inundation. In such a case, the magnitude of drag load is influenced by several parameters, such as the collapse potential, inundation pressure, pile roughness, pile diameter, radius of wetting, depth to the neutral plane, and thickness of collapsible soil subjected to inundation.Methods:A numerical model is developed to simulate the case of a single pile in collapsible soil to predict negative skin friction and drag load by giving consideration to kinetic friction angle between the pile and the settling soil. The comprehensive interdependent relation among the parameters influencing the magnitude of drag load was revealed based on numerical results. Analytical models are developed for predicting the average negative skin friction and depth of neutral plane to quantify drag load because of the inundation of collapsible soil adjacent to the pile shaft.Result and Conclusion:The model coefficients were determined by analyzing the numerical results. The drag loads obtained from the analytical model developed and those from previous experimental studies are found in good agreement. For a given soil profile, the magnitude of drag load is found to vary widely (e.g., between 252 and 925 kN) because of the variations in the pile diameter, pile roughness, and radius of wetting. Thus, this study provides a design guideline for choosing the design pile diameter considering the magnitude of drag load due to inundation of collapsible soil adjacent to the pile shaft.

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Wemmer, Judith, Loredana Malafronte, Socrates Foschini, Aline Schneider, Christian M. Schlepütz, Martin E. Leser, Martin Michel, Adam Burbigde, and Erich J. Windhab. "Fabrication of a Novel Protein Sponge with Dual-Scale Porosity and Mixed Wettability Using a Clean and Versatile Microwave-Based Process." Materials 14, no. 9 (April 29, 2021): 2298. http://dx.doi.org/10.3390/ma14092298.

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An open-porous protein sponge with mixed wettability is presented made entirely from whey proteins and with promising applications in biomedicine, pharmaceutical, and food industry. The fabrication relies on an additive-free, clean and scalable process consisting of foaming followed by controlled microwave-convection drying. Volumetric heating throughout the matrix induced by microwaves causes fast expansion and elongation of the foam bubbles, retards crust formation and promotes early protein denaturation. These effects counteract collapse and shrinkage typically encountered in convection drying of foams. The interplay of high protein content, tailored gas incorporation and controlled drying result in a dried structure with dual-scale porosity composed of open macroscopic elongated foam bubbles and microscopic pores in the surrounding solid lamellae induced by water evaporation. Due to the insolubility and mixed wettability of the denatured protein network, polar and non-polar liquids are rapidly absorbed into the interconnected capillary system of the sponge without disintegrating. While non-watery liquids penetrate the pores by capillary suction, water diffuses also into the stiff protein matrix, inducing swelling and softening. Consequently, the water-filled soft sponge can be emptied by compression and re-absorbs any wetting liquid into the free capillary space.

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Alves, Ilton, Larissa Costa, Antônio Antonino, Lícia Costa, and Silvio Ferreira. "Microstructural analysis of collapsible soil before and after collapse and with loading and unloading cycle." MATEC Web of Conferences 337 (2021): 01004. http://dx.doi.org/10.1051/matecconf/202133701004.

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Aspects related to the volume variation of collapsible soils due to the change in water content are influenced by several factors, including the microstructure. The microstructure analysis of the soil is especially important in order to understand these aspects. This paper shows a comparative analysis of the microstructure of three samples of a collapsible Yellowish Red Sand from the district of Petrolina (northeast of Brazil), carried out by means of two techniques: Scanning Electron Microscope (SEM) and X-Ray Computed Tomography. Three undisturbed sample were used: the first no pressure was applied, in the second an one-dimensional compression of 160 kPa was applied and then the sample was unloaded, and in the third, between the compression and decompression, the sample was flooded with the occurrence of structural collapse. In the first sample, the soil microstructure is a matrix with a predominance of grains of sand clothed with iluvial clay with interconnected pores that confers instability. The second sample showed a reduction in macropores after loading. In the third sample the structure remained with a simple packing arrangement, however, there is a greater packing between the grains, in addition to the wetting-induced softening of the clay particles that fill in the voids. It is also observed, through the radiodensity analysis that at the top and bottom of the second and third samples there was an increase in volume due to the stress relief that is not observed in the central section of the samples. The two microstructure analysis techniques are complementary.

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Eckersley, John David. "Shear strength of stockpiled coking coal – Insights from stability analysis of two instrumented stockpiles." Australian Geomechanics Journal 58, no. 3 (September 1, 2023): 61–73. http://dx.doi.org/10.56295/agj5832.

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ACARP Report C4057 (Eckersley, 2000) describes flowslides and other stability issues in stockpiles of coking (metallurgical) coal at Australian coal operations and export terminals, and summarizes 1973 to 2000 research at James Cook University (JCU). Eckersley (2022) partly updated that work with SEEP/W transient seepage modelling of a 12m high coal stockpile constructed at Hay Point in late 1991. Eckersley (2023) summarized available laboratory strength data for saturated and unsaturated coking coal to assist in selection and critical assessment of parameters for slope stability analyses of coal stockpiles. The current paper explores application of this data to stability analyses of two instrumented experimental stockpiles constructed at Hay Point, one of which collapsed suddenly and completely by flowsliding after extensive wetting. The stability analysis results tentatively confirm that the parameters and approach proposed are reasonable where stockpiles are subject to potential liquefaction-induced collapse. Significant questions raised by Eckersley (2023) regarding how the coking coal strength data should be applied are considered in the context of the stability analyses. The analyses tentatively confirm that effective strength parameters for saturated coal derived from peak deviator stress in isotropically consolidated, undrained (CIU), strain controlled triaxial tests are reasonable. For loose saturated coal these are at low strains and substantially less than critical state values. However, for unsaturated coal forming the bulk of a stockpile, unsaturated strength and apparent cohesion should be assessed from the effective friction angle at critical state and not the value mobilized at low strains. Use of total stress parameters derived from testing unsaturated coal may over-estimate factor of safety.

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Vilar, Orencio Monje. "Discussion of “ Review of Wetting‐Induced Collapse in Compacted Soil ” by Evert C. Lawton, Richard J. Fragaszy, and Mark D. Hetherington (September, 1992, Vol. 118, No. 9)." Journal of Geotechnical Engineering 120, no. 7 (July 1994): 1281–83. http://dx.doi.org/10.1061/(asce)0733-9410(1994)120:7(1281).

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Lawton, Evert C., Richard J. Fragaszy, and Mark D. Hetherington. "Closure to “ Review of Wetting‐Induced Collapse in Compacted Soil ” by Evert C. Lawton, Richard J. Fragaszy, and Mark D. Hetherington (September, 1992, Vol. 118, No. 9)." Journal of Geotechnical Engineering 120, no. 7 (July 1994): 1283–84. http://dx.doi.org/10.1061/(asce)0733-9410(1994)120:7(1283).

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Sulaiman, Hadeel S., Muayad A. Al-Sharrad, and Idham A. Abed. "Biocalcification of Sandy Gypseous Soil by Bacillus Pasteurii." Salud, Ciencia y Tecnología - Serie de Conferencias 3 (June 2, 2024): 818. http://dx.doi.org/10.56294/sctconf2024818.

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Microbial-induced carbon precipitation (MICP) is one of the most recent treatment methods for soil stabilization. The present work employs this technique in improving the collapsing behavior of sandy gypseous soil with 35% gypsum content under one-dimensional loading to 100 kPa and leaching conditions. A bacterial strain, Bacillus pasteurii was used for this purpose. A set of collapse tests was performed inside a modified oedometer on specimens, prepared with 25% bacterial solution and 0, 0.25M, 0.5M, or 1M cementation solution molarities, cured to 7, 14, or 21 days. The results indicated that the bacterium was able to produce a considerable amount of calcium carbonate ranging from 3% to 15%. This carbonate was also observed by microscopic imaging of the specimens at the interparticle contacts and also on the surfaces of soil grains. Consequently, the soil gained additional bonding and the voids became smaller. Therefore, the soil became more resistant to water flow and leaching, where the treated specimen maintained nearly the same permeability with the progression of leaching, unlike the untreated specimen which showed a 7-fold increase over the same water flow condition. Over the examined load, the MICP treatment provided almost no change in the strains caused by external loading, unlike the wetting strains which exhibited a considerable reduction of 11% to 80%. The results of leaching strains appeared to be sensitive to the rate of flow and the cementation solution molarity

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Reyssat, Etienne. "Drops and bubbles in wedges." Journal of Fluid Mechanics 748 (May 6, 2014): 641–62. http://dx.doi.org/10.1017/jfm.2014.201.

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AbstractWe investigate experimentally the spontaneous motion of drops and bubbles confined between two plates forming a narrow wedge. Such discoidal objects migrate under the gradient in interfacial energy induced by the non-homogeneous confinement. The resulting capillary driving force is balanced by viscous resistance. The viscous friction on a drop bridging parallel plates is estimated by measuring its sliding velocity under gravity. The viscous forces are the sum of two contributions, from the bulk of the liquid and from contact lines, the relative strength of which depends on the drop size and velocity and the physical properties of the liquid. The balance of capillarity and viscosity quantitatively explains the dynamics of spontaneous migration of a drop in a wedge. Close the tip of the wedge, bulk dissipation dominates and the migrating velocity of drops is constant and independent of drop volume. The distance between the drop and the tip of the wedge is thus linear with time $t$, $x(t) \sim t_0-t$, where $t_0$ is the time at which the drop reaches the tip of the wedge. Far away from the apex, contact lines dominate the friction, the motion is accelerated toward the tip of the wedge and velocities are higher for larger drops. In this regime, it is shown that $x(t) \sim (t_0-t)^{4/13}$. The position and time of the crossover between the two dissipation regimes are used to write a dimensionless equation of motion. Plotted in rescaled variables, all experimental trajectories collapse to the prediction of our model. In contrast to drops, gas bubbles in a liquid-filled wedge behave as non-wetting objects. They thus escape the confinement of the wedge to reduce their surface area. The physical mechanisms involved are similar for drops and bubbles, so that the forces acting have the same mathematical structures in both cases, except for the sign of the capillary driving force and a numerical factor. We thus predict and show experimentally that the trajectories of drops and bubbles obey the same equation of motion, except for a change in the sign of $t_0-t$.

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Jia, Jun, Xiangjun Pei, Xiaopeng Guo, Shenghua Cui, Pingping Sun, Haoran Fan, Xiaochao Zhang, and Qi Gu. "Laboratory Model Tests on the Deformation and Failure of Terraced Loess Slopes Induced by Extreme Rainfall." Land 13, no. 10 (October 8, 2024): 1631. http://dx.doi.org/10.3390/land13101631.

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Heavy rainfall is the main factor inducing the failure of loess slopes. However, the failure mechanism and mode of terraced loess slopes under heavy rainfall have not been well investigated and understood. This paper presents the experimental study on the deformation and failure of terraced loess slopes with different gradients under extreme rainfall conditions. The deformation and failure processes of the slope and the migration of the wetting front within the slope during rainfall were captured by the digital cameras installed on the top and side of the test box. In addition, the mechanical and hydrological responses of the slope, including earth pressure, water content, pore water pressure, and matric suction, were monitored and analyzed under rainfall infiltration and erosion. The experimental study shows that the deformation and failure of terraced loess slopes under heavy rainfall conditions exhibit the characteristic of progressive erosion damage. In general, the steeper the slope, the more severe the deformation and failure, and the shorter the time required for erosion failure. The data obtained from sensors embedded in the slope can reflect the mechanical and hydraulic characteristics of the slope in response to rainfall. The earth pressure and pore water pressure in the slope exhibit a fluctuating pattern with continued rainfall. The failure mode of terraced loess slopes under extreme rainfall can be summarized into five stages: erosion of slope surface and formation of small gullies and cracks, expansion of gullies and cracks along the slope surface, widening and deepening of gullies, local collapse and flow-slip of the slope, and large-scale collapse of the slope. The findings can provide preliminary data references for researchers to better understand the failure characteristics of terraced loess slopes under extreme rainfall and to further validate the results of numerical simulations and analytical solutions.

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Aljammaz, Abdulaziz, Mohamed Sultan, Moein Izadi, Abotalib Z. Abotalib, Mohamed S. Elhebiry, Mustafa Kemal Emil, Karem Abdelmohsen, Mohamed Saleh, and Richard Becker. "Land Subsidence Induced by Rapid Urbanization in Arid Environments: A Remote Sensing-Based Investigation." Remote Sensing 13, no. 6 (March 15, 2021): 1109. http://dx.doi.org/10.3390/rs13061109.

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The rapid increase in the population of many of the older major cities within the countries of the Saharan-Arabian Desert is steering vast and disorganized urban expansion and in many cases introducing adverse environmental impacts such as soil erosion, rise in groundwater levels, and contamination of shallow aquifers, as well as development of deformational features including land subsidence. Using the rapidly growing city of Riyadh (1992: 467 km2; 2018: 980 km2), the capital of the Kingdom of Saudi Arabia as a test site, we utilized Small Baseline Subset (SBAS) interferometric analyses of 2016 to 2018 Sentinel-1 images together with multi-temporal high-resolution images viewable on Google Earth, GPS, field, land use land cover (LULC), and geological data to assess the distribution and rates of land subsidence and their causal effects. Three main causes of subsidence were identified and assessed: (1) discharge of wastewater effluents from septic systems in newly urbanized areas that lead to an increase in soil moisture, rise in groundwater levels, waterlogging, and wetting and hydrocompaction of dry alluvium loose sediments causing land subsidence (up to −20 mm/y) in wadis and lowlands; (2) the subsurface dissolution of karst formation by wastewater effluents and the collapse of voids and cavities at depth under stresses introduced by heavy construction machinery, causing sagging and land subsidence (up to −5 mm/y); and (3) leveling, compaction, and degradation of municipal and building waste materials in organized landfills and disorganized dump sites that resulted in significant land subsidence (up to −21 mm/y) and differential settling that could jeopardize the stability of structures erected over these sites. Our findings highlight the potential use of the advocated integrated approach to assess the nature and extent of land deformation associated with rapid urban growth in arid lands, and to identify areas most impacted for the purpose of directing and prioritizing remediation efforts.

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Ambord, Sarah, Michael H. Stoffel, and Rupert M. Bruckmaier. "Teat anatomy affects requirements for udder preparation in Mediterranean buffaloes." Journal of Dairy Research 77, no. 4 (September 8, 2010): 468–73. http://dx.doi.org/10.1017/s0022029910000518.

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The present study was conducted to assess the interrelation between teat anatomy and machine milking in dairy buffaloes raised in Switzerland. A 3-min pre-stimulation induced milk ejection before cluster attachment in most cases and caused an optimal milk removal during machine milking. In an additional experiment, longitudinal cross-section ultrasound was obtained before and after a 3-min pre-stimulation. Teat wall thickness, teat diameter, cisternal diameter and teat canal length were evaluated. It was observed that 3-min pre-stimulation dramatically reduced teat canal length whereas all the other anatomical parameters remained unchanged. The vacuum needed to open the teat canal was also measured before and after a 3-min pre-stimulation by using a special teat cup with only the mouthpiece of the liner remaining on the top of the teat cup (no liner, no pulsation). Without pre-stimulation but after wetting the teat canal by stripping one squirt of milk out of the teat, no milk could be withdrawn with a vacuum up to 39 kPa. However, after pre-stimulation, milk flow occurred in all buffaloes at a vacuum between 16 and 38 kPa. In the last experiment, the teat tissue was examined in slaughtered buffaloes and compared with teat tissue of cows. No difference was noted in histological sections and teat canal length was similar in cows and buffaloes. Proximal to the teat canal, the teat did not pass into an open cistern but the lumen was collapsed. In conclusion, buffaloes need to be well pre-stimulated because the tissue above the teat canal provides additional teat closure before milk ejection. Therefore, milk can only be obtained after pre-stimulation.

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42

Wang, Yuanyuan, and Yanrong Li. "Wetting-induced collapse of loess: Tracing microstructural evolution." Engineering Geology, August 2024, 107673. http://dx.doi.org/10.1016/j.enggeo.2024.107673.

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43

"Review of wetting-induced collapse in compacted soil." International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 30, no. 2 (April 1993): A92. http://dx.doi.org/10.1016/0148-9062(93)90878-h.

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44

Kim, Jongchan, Junghee Park, and Hyunwook Choo. "Shear wave implications in wetting-induced collapse of sand–clay mixtures." Bulletin of Engineering Geology and the Environment 83, no. 8 (July 12, 2024). http://dx.doi.org/10.1007/s10064-024-03814-7.

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45

Yuan, Chao, Mariagiovanna Moscariello, Sabatino Cuomo, and Bruno Chareyre. "Numerical simulation of wetting-induced collapse in partially saturated granular soils." Granular Matter 21, no. 3 (June 29, 2019). http://dx.doi.org/10.1007/s10035-019-0921-7.

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46

Bahloul, Ouassila, Khelifa Abbeche, Azeddine Bahloul, and Amor Halitim. "EFFECT OF SODIUM CHLORIDE ON THE WETTING INDUCED COLLAPSE STRAIN OF SOILS." Malaysian Journal of Civil Engineering 26, no. 2 (July 2, 2018). http://dx.doi.org/10.11113/mjce.v26.15881.

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Collapsible soils are unsaturated soils which present the potential for large strains and complete change to the whole particle structure after wetting with or without loading. These soils are characterized with loose structures composed of silt to fine-sand-size particles. Collapsible soils are deposited in arid and semi-arid regions. Due to the expansion of human activities, these regions are occupied aggressively leading to the use of large quantities of water which create favorable conditions for soil collapse. The soils failure leads to severe damages and large distresses to man-made structures. The experimental study on reconstituted soil in laboratory consists of the evaluation of the effect of a saline solution of sodium chloride at different, water content and levels of compaction energy on the collapsible potential. The method used is based on oedometer tests with variation of the vertical stress. The study clearly reveals the influence of the salt concentration on the change of microstructural characteristics of the reconstituted soil and reduction of the collapse potential .

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Farsijani, Ali, and Ahad Ouria. "Wetting-Induced Collapse Behavior of Unsaturated Soils in Disturbed State Concept Framework." International Journal of Geomechanics 22, no. 4 (April 2022). http://dx.doi.org/10.1061/(asce)gm.1943-5622.0002327.

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Song, Zhaoyang, Tiantian Ma, Guoqing Cai, Yan Liu, and Changfu Wei. "An effective stress-based approach to modeling the hydro-mechanical behavior of unsaturated soils." Canadian Geotechnical Journal, January 19, 2024. http://dx.doi.org/10.1139/cgj-2022-0234.

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A constitutive model of unsaturated soils is developed by incorporating the concept of intergranular stress into the framework of the modified Cam-Clay model. Within this context, the degree of saturation is viewed as an internal state variable, so that the soil-water retention function appears naturally as an evolution equation for the volume fraction of water. The new model not only has a neat structure but also includes fewer material parameters compared to the other models. A new volumetric-hardening law is proposed by taking into account the effect of wetting-induced pore collapse. It is shown that the collapsing void ratio (the current void ratio minus the void ratio at full saturation under the same effective stress) is dominated by the degree of pore air saturation (one minus the degree of water saturation), and practically independent of intergranular pulling forces, highlighting the important effect of soil fabric on the wetting-induced pore collapse. The proposed model is applied to simulate different types of experiments on unsaturated soils subjected to various combined hydraulic and mechanical loadings, showing its capability and diversity in modeling the hydraulic and mechanical behavior of unsaturated soils.

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Albuja-Sánchez, Jorge, Jessica Duque, Lizmary Martin, Jonathan Morales, and Mariela Anaguano-Marcillo. "DETERMINATION OF THE MATRIX SUCTION OF LOW-PLASTICITY SILTS AND ITS CORRELATION WITH THEIR COLLAPSE POTENTIAL." Proceedings of International Structural Engineering and Construction 11, no. 1 (March 2024). http://dx.doi.org/10.14455/isec.2024.11(1).gfe-02.

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Soils are usually in a partially saturated state, meaning that both air and water occupy their voids. This condition can affect the stability of structures because it is closely related to wetting deformation (collapse). A low-plasticity silt (ML) composed of 45% kaolin with a liquid limit of 36% and a plasticity index of 10% was used in this study. In this study, the soil suction matrix was determined using the filter paper method established in ASTM D5298, correlating it with the moisture content and percentage of deformation induced by wetting. It was concluded that, as the moisture content decreases, the suction and the percentage of deformation by wetting increase, since, for a moisture content of 9% the suction is 14901.6 kPa and the deformation is 0.58%, while for a moisture content of 21% the suction is 1028.1 kPa and the deformation is 0.07%. Thus, a change in the slope of the SWRC was evident starting at 9%, which indicates a greater effect of suction and deformation below this moisture content.

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50

Das, Amiya Prakash, Jidong Zhao, and Thomas Sweijen. "Micromechanical modeling of triphasic granular media." Proceedings of the National Academy of Sciences 122, no. 18 (May 2, 2025). https://doi.org/10.1073/pnas.2420314122.

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This paper presents pore unit assembly-discrete element model (PUA-DEM), a pore-scale hydromechanical framework that resolves interactions between mobile granular particles and multiphase fluids in unsaturated granular media. The framework uniquely integrates DEM with pore-scale hydrodynamic models to capture unsaturated flow dynamics, while leveraging a two-way coupling mechanism to ensure bidirectional fluid–grain feedback through stabilized domain partitioning. Further innovations include a dynamic pore-merging and retriangulation algorithm that enhances computational efficiency for large-scale systems. Validated against experimental data for glass beads and Ottawa sand, PUA-DEM accurately reproduces critical hydromechanical phenomena-including capillary/viscous fingering, wetting-induced granular swelling/collapse, and quasi-static deformation-under diverse saturation and loading regimes. Numerical case studies reveal how capillary forces and wetting fluid saturation collectively govern granular response, from pore-scale meniscus evolution to macroscale flow instabilities. By bridging pore- and particle-scale physics, PUA-DEM advances predictive modeling of partially saturated granular systems, offering transformative insights for geohazard mitigation, sustainable agriculture, pharmaceutical manufacturing, and energy-related engineering applications.

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Journal articles on the topic 'Wetting-induced collapse'

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