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1
Dong, Yun, Yong Cun Wang, Li Guo Lu, and Wei Wang. "The Improved Shear Strength Calculation Method in Direct Shear Test." Applied Mechanics and Materials 405-408 (September 2013): 353–57. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.353.
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Direct shear test is broadly used to get the strength of soil, joints, and specific material in the field of geotechnical engineering because its simple structure and easier operation. But the current direct shear strength calculation does not concern on the variation of the shearing surface during the test, has no regard for the effects of the shearing area on the shear strength, so the test result is not the really strength of the samples. To discovery the affection of the shearing surface on the direct shear strength, three different calculation methods of shear surface and its affection on the shear strength were put forward based on the new mathematical model and large number of experimental with improvement direct shear apparatus, the new calculation method makes the result more accuracy and closer to the really shear strength of the samples.
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Hwang, Byongyoun, Tae-Young Kwak, Jongkwan Kim, and Jin-Tae Han. "Liquefaction Characteristics of Sands Based on Cyclic Direct Simple Shear Test." Journal of the Korean Society of Hazard Mitigation 20, no. 4 (August 31, 2020): 239–49. http://dx.doi.org/10.9798/kosham.2020.20.4.239.
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In this study, a series of cyclic direct simple shear tests were conducted on Pohang sand, Jumunjin sand, and Ottawa sand. The cyclic resistance ratio (CRR) was derived on the basis of the test results obtained. For verification of the effect of particle distribution on liquefaction resistance, the simplified method for evaluation of the possibility of liquefaction was used to assess these sands. The test results showed that the cyclic resistance ratio of Pohang sand was the lowest, which was consistent with the result of the simplified evaluation method for determining the possibility of liquefaction. In addition, the results showed that the liquefaction resistance increased for particle shapes being more angular than round. Normalization was subsequently applied to minimize the effects of the different factors, and the correlation between the CRR<sub>N=10</sub> normalization curve and the CRR<sub>N=15</sub> normalization curve was confirmed.
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Doherty, James, and Martin Fahey. "Three-dimensional finite element analysis of the direct simple shear test." Computers and Geotechnics 38, no. 7 (November 2011): 917–24. http://dx.doi.org/10.1016/j.compgeo.2011.05.005.
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Rossato, Gianni, and Paolo Simonini. "Stress–strain behaviour of sands in triaxial and direct simple shear tests." Canadian Geotechnical Journal 28, no. 2 (April 1, 1991): 276–81. http://dx.doi.org/10.1139/t91-033.
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The behaviour of a natural sand in triaxial compression and direct simple shear tests was compared by means of dimensionless analysis of parameters controlling the evolution of stresses and strains. The secant triaxial compression and direct simple shear moduli were interpreted in a dimensionless form. A criterion based on the equivalence between major principal strain in the two tests was considered to compare the results. Key words: sand, stress–strain behaviour, triaxial test, direct simple shear test, shear modulus, triaxial compression modulus.
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Xiong, Meng, Pengfei He, Yanhu Mu, and Xinlei Na. "Modeling of Concrete-Frozen Soil Interface from Direct Shear Test Results." Advances in Civil Engineering 2021 (January 2, 2021): 1–11. http://dx.doi.org/10.1155/2021/7260598.
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The shear behaviors of concrete-frozen soil interface are important for analyzing the performance of engineering structures buried in the frozen ground. In this paper, a series of direct shear tests were carried out to determine the concrete-soil interface behaviors at different test temperatures (19°C, −1°C, −3°C, and −5°C) and initial water contents (9.2%, 13.1%, 17.1%, and 20.8%) of soils. The interface shear behaviors, including the shear stress versus horizontal displacement, interface cohesion, and interface friction coefficient, were analyzed based on the test results. Then, a simple, nonlinear model was proposed and verified for the interface shear behaviors. The results show that the effect of initial water content and test temperature on the interface shear behavior is significant, and the peak stress increases with the increasing initial water content and decreasing test temperature. The interface cohesion is sensitive to the test temperature and initial water content, while the interface friction coefficient is insensitive to both the factors. The parameters of the simple nonlinear model can be gained by back-analyzing the test results. The predictions made by the proposed model are found to be in good agreement with the experimental results.
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Liu, S. H. "Simulating a direct shear box test by DEM." Canadian Geotechnical Journal 43, no. 2 (February 1, 2006): 155–68. http://dx.doi.org/10.1139/t05-097.
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Distinct element simulation was performed for direct shear box (DSB) tests on a dense and a loose two-dimensional (2D) sample of 3259 cylinders. Special attention was devoted to the effect that the frictional force between the inside surface of the upper shear box and the sample had on the measured shear strength in the DSB test. Some ways of minimizing this interface frictional force were introduced in the paper. Given that the deformation approximates simple shear within the deforming zone across the sample centre (referred to as the shear zone), a method was proposed to evaluate the overall strains in the DSB test. The numerically simulated data were used to interpret, on a microscopic scale, the angle of internal friction and a 2D stressdilatancy equation for the mobilized plane in granular material. It was found that the angle of internal friction in granular material is not directly related to the interparticle friction angle (ϕµ). Instead, it relates to the average interparticle contact angle ([Formula: see text]) on the mobilized plane and the ratio k/f0, representing the degree of the probability distribution of the interparticle contact forces that is biased toward the positive zone of the contact angle θ (along the shear direction), where k is the slope of the linear distribution of the average interparticle contact forces against the interparticle contact angle; and f0 is the average interparticle contact force.Key words: angle of internal friction, direct shear box test, distinct element method, friction, granular material, stressdilatancy.
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Haythornthwaite, Robert M. "Simple Shear in Granular Media." Applied Mechanics Reviews 50, no. 11S (November 1, 1997): S81—S86. http://dx.doi.org/10.1115/1.3101854.
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The ring shear box is analyzed using an isotropic strain hardening/softening model for granular media, permitting an estimate to be made of the stresses developed under conditions of simple shear, at the critical void ratio. Observation of the radial stress on the inner or outer walls of the test chamber would provide a measure of the relative value of the otherwise unknown intermediate principal stress. In a series of five tests on a quartz sand, average pressures exerted by the sand on the outer wall of the test chamber reached well defined, repeatable levels. As interpreted by the theory, the tests showed that the intermediate principal stress was equal to the direct stress on the Coulomb friction planes during simple shear: (1−sinφcv)σ1=σ2=(1+sinφcv)σ3 where σ1 > σ2 > σ3 (compression positive), and φcv is the angle of internal friction at the critical void ratio, ie, during continuing displacement at constant volume. Similar observations are impossible for plane strain in general because displacement cannot be controlled so completely, but it is reasonable to conjecture that the same relationship holds for all such deformations, including those associated with the active and passive Rankine states.
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Wang, Cheng Hua, Kui Jin, and Chuan Zhan. "Model Test Studies of the Mechanical Properties of Pile - Soil Interface." Applied Mechanics and Materials 392 (September 2013): 904–8. http://dx.doi.org/10.4028/www.scientific.net/amm.392.904.
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The study of the mechanical properties of pile-soil interface is an important aspect to research the vertical bearing behavior of piles. Currently special direct shear tests and special simple shear tests are usually used to study the mechanical properties of soil-structure interface. But those tests have shortcomings of difficulty in simulating the force properties of complex interface. In this paper, the mechanical properties of different interface between soil and concrete surface were studied through the large-scale direct shear tests.
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Le, K. N., and M. Ghayoomi. "Cyclic Direct Simple Shear Test to Measure Strain-Dependent Dynamic Properties of Unsaturated Sand." Geotechnical Testing Journal 40, no. 3 (April 12, 2017): 20160128. http://dx.doi.org/10.1520/gtj20160128.
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Zainorabidin, Adnan, and Siti Hajar Mansor. "Comparative Study of Stress-Strain Characteristic of Peat Soil." Applied Mechanics and Materials 773-774 (July 2015): 1448–52. http://dx.doi.org/10.4028/www.scientific.net/amm.773-774.1448.
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This paper shows the stress-strain behavior of peat from the perspective of geotechnical engineering based on laboratory test. Stress happens when a load applied to a certain specimen and deformed the specimen while strain is the response from applied stress on a specimen. Peat is known as an ultimate soft soil in engineering terms because it has low shear strength and compressibility. This research is concerned about the stress-strain behavior of hemic peat. The undisturbed samples were collected at Parit Sulong and Parit Nipah, Batu Pahat, Johore, Malaysia. Normal stresses are 12.5kPa, 25kPa, 50kPa and 100kPa. The shear rate to determine the stress-strain on peat is 0.1mm/min. It is a drained condition test. Both results from each method that obtained were compared based on the relationships of stress-strain. Parit Sulong has higher stress-strain than Parit Nipah. If shear stress increased, shear strain also increased. The result shows that, direct simple shear test of stress-strain that tested on hemic is more relevant than a direct shear box because DSS shear the entire specimen of peat while DSB only shear at the center of the specimen. Geotechnical engineers can use the direct simple shear method to understand efficiently about the stress-strain behaviour of peat.
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Oloo, S. Y., and D. G. Fredlund. "A method for determination of ϕb for statically compacted soils." Canadian Geotechnical Journal 33, no. 2 (May 8, 1996): 272–80. http://dx.doi.org/10.1139/t96-006.
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The unsaturated shear strength parameter, ϕb, is usually determined using triaxial of direct shear apparatus that have been modified to allow for the control and (or) measurement of pore-air and pore-water pressures. A fairly high level of expertise is required for the characterization of ϕb using these modified apparatus. A simple procedure for determining ϕb for statically compacted soils at different water contents is presented along with a method of analysis. The tests can be performed on a conventional direct shear apparatus. The unsaturated shear strength parameter, ϕb, obtained using the proposed procedure is shown to be comparable to that obtained using the modified direct shear test. Since the proposed procedure utilizes standard laboratory direct shear equipment and takes a relatively short time to complete, it offers an easy and convenient alternative for the determination of ϕb for statically compacted soils. Key words: shear strength, matric suction, unsaturated soils, statically compacted soils, direct shear test.
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Fan, Meng Hua. "Using Excel to Evaluate Shear Strength Parameters of Soil." Advanced Materials Research 709 (June 2013): 579–82. http://dx.doi.org/10.4028/www.scientific.net/amr.709.579.
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It is difficult to determine the Mohr-Coulomb failure envelope visually, and it is strongly influenced by abnormal test data evaluating the shear strength parameters of soil via trend line and unable to adjust the scope of permissible error. So it is recommended to evaluate shear strength parameters of soil using Solver of Excel for direct shear tests and triaxial tests and you can control the allowable deviation. The mathematics model of nonlinear programming was established to evaluate shear strength parameters of soil from the results of direct shear test and triaxial shear test. The related Excel worksheet was created and the optimum results of the objective function were obtained by setting the Solver parameters dialog box accurately. The method is simple, inexpensive and rapid.
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Olson, Scott M., and Benjamin B. Mattson. "Mode of shear effects on yield and liquefied strength ratios." Canadian Geotechnical Journal 45, no. 4 (April 2008): 574–87. http://dx.doi.org/10.1139/t07-114.
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A database of 386 laboratory triaxial compression, direct simple shear, rotational shear, and triaxial extension test results was collected to examine yield and liquefied strength ratio concepts used in liquefaction analysis of sloping ground. These data envelope the yield and liquefied strength ratios obtained from back-analyses of liquefaction flow failure case histories. Generally, triaxial compression exhibits the highest yield and liquefied strength ratios, triaxial extension yields the lowest ratios, and direct simple shear – rotational shear shows intermediate responses. However, mode of shear appears to have a considerably smaller effect on laboratory-measured liquefied strength ratios for specimens with a positive state parameter (i.e., difference in consolidation void ratio and steady state void ratio at the same effective stress).
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Schmitt, François G. "Direct test of a nonlinear constitutive equation for simple turbulent shear flows using DNS data." Communications in Nonlinear Science and Numerical Simulation 12, no. 7 (October 2007): 1251–64. http://dx.doi.org/10.1016/j.cnsns.2006.01.015.
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Tejchman, J., and E. Bauer. "Fe-simulations of a direct and a true simple shear test within a polar hypoplasticity." Computers and Geotechnics 32, no. 1 (January 2005): 1–16. http://dx.doi.org/10.1016/j.compgeo.2004.11.004.
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Al Tarhouni, Mahmud Amer, and Bipul Hawlader. "Monotonic and cyclic behaviour of sand in direct simple shear test conditions considering low stresses." Soil Dynamics and Earthquake Engineering 150 (November 2021): 106931. http://dx.doi.org/10.1016/j.soildyn.2021.106931.
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Chang, Tzu-Chuan, Abrahán Bechara Senior, Hakan Celik, Dave Brands, Angel Yanev, and Tim Osswald. "Validation of Fiber Breakage in Simple Shear Flow with Direct Fiber Simulation." Journal of Composites Science 4, no. 3 (September 10, 2020): 134. http://dx.doi.org/10.3390/jcs4030134.
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This study aims to use particle level simulation to simulate the breakage behavior of glass fibers subjected to simple shear flow. Each fiber is represented as a chain of rods that experience hydrodynamic, interaction, and elastic effects. In order to validate the approach of the model, the simulation results were compared to simple shear flow experiments conducted in a Couette Rheometer. The excluded volume force constants and critical fiber breakage curvature were tuned in the simulation to gain a better understanding of the system. Relaxation of the fiber clusters and a failure probability theory were introduced into the model to solve the fiber entanglement and thus, better fit the experimental behavior. The model showed agreement with the prediction on fiber length reduction in both number average length and weight average length. In addition, the simulation had a similar trend of breakage distribution compared to a loop test using glass fibers.
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Vaid, Y. P., and S. Sivathayalan. "Static and cyclic liquefaction potential of Fraser Delta sand in simple shear and triaxial tests." Canadian Geotechnical Journal 33, no. 2 (May 8, 1996): 281–89. http://dx.doi.org/10.1139/t96-007.
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The potential for static and cyclic liquefaction of the sand that underlies the highly seismic Fraser Delta is assessed under simple shear test conditions, typical of an earthquake shaking. A comparison of liquefaction potential is also made between simple shear and conventional triaxial stress conditions. It is shown that the liquefaction potential of sand is profoundly influenced by the stress path. The reduction factors currently applied to the cyclic triaxial resistance for representing simple shear response may involve a large degree of conservatism in design. A direct measurement of soil behaviour under stress conditions typical of earthquake loading may thus have large economic benefits. Key words: sand, liquefaction, static, cyclic, triaxial, simple shear.
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Du, Jia-Chong. "EVALUATION OF ASPHALT PAVEMENT LAYER BONDING STRESS." Journal of Civil Engineering and Management 21, no. 5 (May 6, 2015): 571–77. http://dx.doi.org/10.3846/13923730.2014.890664.
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This study is to evaluate the bonding shear stress between asphalt pavement layered structures with emulsion and cutback asphalt as tack coat materials. A simple direct shear test device is set up for testing the shear force of the pavement composite interface. The test results show that the shear force decreases with an increase in temperature. It had a maximum value at optimum application rate and the emulsion asphalt used exhibited higher shear force than that of cutback asphalt. The shear stress model represented by exponential equations between shear stress and temperature is reasonable and is not significantly different to the shear stress from experimental field test, in accordance with the statistic of analysis of variance test. The shear stress modeling developed in this paper provides a valuable method to simulate the shear stress of a different nominal aggregate gradation and tack coat material.
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Amirpour Harehdasht, Samaneh, Varvara Roubtsova, Mohamed Chekired, Mahmoud N. Hussien, and Mourad Karray. "Micromechanics-based assessment of reliability and applicability of boundary measurements in symmetrical direct shear test." Canadian Geotechnical Journal 55, no. 3 (March 2018): 397–413. http://dx.doi.org/10.1139/cgj-2017-0274.
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Development of the discrete element method (DEM) has provided an efficient tool to examine and appraise the performance of a direct shear apparatus (DSA) to overcome ambiguities that arise from the complexity of stress and strain distributions involved. This paper presents DEM analyses of both macro- and micromechanics responses of three-dimensional dense samples of 102 248 glass spheres tested in virtual symmetrical DSA using the computer code SiGran. Particular emphasis is placed on the validation of the DEM model by comparing the results of DEM simulations with their physical counterparts at the macroscale. The performance of the physical direct shear apparatus is optimized by exploring modifications to the symmetrical test configuration. Numerical results provide quantitative data on different forms of energy consumed during shearing, confirming other published physical and numerical results found in the literature. Virtual DSA results are also discussed in terms of the coaxiality between the directions of the principal stresses’ and the principal strains’ increments as well as the deviation of the zero extension direction from the horizontal direction. Microscale results show that peak state parameters obtained from the symmetrical arrangement, adopted in this study, are very close to those of an ideal simple shear test, as this arrangement permits a uniform deformation within the developed shear band, a horizontal orientation of the zero linear extension, and a coaxiality of principal stresses and incremental strains at the peak state. In other words, the microscale results presented in this study provide new evidence that corroborates the further use of the boundary measurements in physical symmetrical direct shear tests.
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Chen, Gao Feng, Ying Fa Lv, Zhi Huai Huang, and Yan Chang. "Study on Shear Strength Experiments Base on the Modified Direct Shear Apparatus for Unsaturated Soils." Applied Mechanics and Materials 438-439 (October 2013): 1176–80. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.1176.
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The unconsolidated-undrained fast shear tests of saturated-unsaturated remolded soil samples under different moisture content which is 1.1%, 10.1%, 14.9%, 19.9%, 24.2%, 29.9%, 37.7% respectively, and normal stress which is 50kPa, 100kPa, 200kPa, 300kPa, 400kPa respectively, were studied by the modified SDJ-1-type strain direct shear apparatus and U.S. Lab VIEW data acquisition system. The shear strength parameters of unsaturated soil samples, i.e. general cohesion and general internal friction angle were obtained based on Mohr-Coulomb strength theory. The test results showed that the general cohesion firstly increased and then reduced with the moisture content increasing, and the general internal friction angle increased with the moisture content decreasing. The function between the general shear strength parameters and the moisture content was studied. The concept of general shear strength parameters was proposed in the paper, and would provide a simple and practical method to obtain the strength parameters for engineering practice.
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MONTANERO, J. M., V. GARZÓ, A. SANTOS, and J. J. BREY. "Kinetic theory of simple granular shear flows of smooth hard spheres." Journal of Fluid Mechanics 389 (June 25, 1999): 391–411. http://dx.doi.org/10.1017/s0022112099005182.
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Steady simple shear flows of smooth inelastic spheres are studied by means of a model kinetic equation and also of a direct Monte Carlo simulation method. Both approaches are based on the Enskog equation and provide for each other a test of consistency. The dependence of the granular temperature and of the shear and normal stresses on both the solid fraction and the coefficient of restitution is analysed. Quite a good agreement is found between theory and simulations in all cases. Also, simplified expressions based on the analytical solution of the model for small dissipation are shown to describe fairly well the simulation results even for not small inelasticity. A critical comparison with previous theories is carried out.
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Amelian, Soroosh, and Yong-Rak Kim. "Performance Assessment of Interlayers with Different Tack Coats by Considering Loading Types and Failure Modes." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 28 (May 4, 2018): 1–9. http://dx.doi.org/10.1177/0361198118768528.
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A monotonic direct shear test (DST) is the most commonly used method to evaluate bond strength of interlayers; however, it does not consider the actual repetitive traffic loading that pavement undergoes during its service life. This study aims to examine the link between various parameters obtained from a monotonic DST and the results of a cyclic loading test that more realistically assesses the interlayer performance with tack coats. Furthermore, to investigate the possible effect of the interface failure mode (shear vs. tensile) on the performance assessment of the tack coat interlayers, a simple indirect tensile test was conducted to determine the tensile strength of the interlayers. Field core samples extracted from a test section constructed in Nebraska were used for various laboratory tests. The field test section included 14 subsections containing various types of tack coat materials with different application methods. Permanent shear deformation and interface stiffness were selected as the failure criteria to characterize the interface resistance associated with cyclic load repetition. Shear strength, shear stiffness, and interlayer bond energy were chosen as the failure criteria for the monotonic DST. Results show that the interlayer shear strength from the monotonic DST had an acceptable correlation with the cyclic test results, and interlayer bond energy is a good predictor of the shear resistance of the tack coats with a high correlation with the cyclic test. The simple indirect tensile test was capable of differentiating interlayer performance with different types of tack coating.
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Cady, Carl M., Cheng Liu, Carl P. Trujillo, Donald W. Brown, and George T. Gray III. "The Shear Response of Beryllium as a Function of Temperature and Strain Rate." EPJ Web of Conferences 183 (2018): 02017. http://dx.doi.org/10.1051/epjconf/201818302017.
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A new specimen design has been developed to measure the shear response of materials. This compact forced-simple-shear specimen (CFSS) has been utilized to measure the shear stress/shear strain response of other materials [1, 2]. Earlier, unpublished work on the shear response of beryllium using a split Hopkinson pressure bar (SHPB) with the shear compression specimen (SCS) [3] had limited success at higher strain rates due to compressive deformation in the web leading to tensile failure in the samples. The CFSS geometry was engineered to produce essentially “pure” simple shear, mode II in-plane shear, in a compact-sample geometry that eliminates the multi-mode loading of other sample geometries and produces direct measurements of shear deformation. The use of digital image correlation (DIC) to capture and calculate shear stress and shear strain when paired with this test geometry will be described. There are two competing mechanisms for the deformation in beryllium were observed, a brittle to ductile response due to increased temperature and a transition of the deformation mechanism from dislocation dominated slip to twin deformation as the strain rate is increased. The advantages of this specimen geometry and test results as a function of temperature and strain rate are discussed for high purity beryllium.
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Moussa, Ahmed, Hany El Naggar, and Abouzar Sadrekarimi. "Dynamic Properties of Granulated Rubber Using Different Laboratory Tests." Buildings 11, no. 5 (April 28, 2021): 186. http://dx.doi.org/10.3390/buildings11050186.
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Due to the socio-environmental hazards arising from the stockpiling of disposed scrap tires, the necessity to utilize such material in civil construction and other applications is deemed mandatory. The lightweight of rubber and its high damping capacity are excellent properties of a geomaterial that could be used successfully in seismic isolation and vibration damping applications in civil construction. Scrap tires could be shredded into specific sizes, and their category and application depend on their particle size range. Thus, understanding the dynamic properties and behavior of shredded scrap tires under cyclic loading is of paramount importance. In this study, the dynamic characteristics of granulated rubbers (<12 mm) are investigated using cyclic triaxial and cyclic direct simple shear tests. The effect of using different testing techniques, i.e., cyclic triaxial test (CTT) and cyclic simple shear test (CSST), on the dynamic properties of granulated rubber material is further addressed. Undrained cyclic triaxial and constant-volume direct simple shear tests are conducted on granulated rubber samples under vertical consolidation stresses of 25, 50, 100 and 200 kPa at a frequency of 0.5 Hz. The shear strain amplitude is varied from 0.01% to 10%. Furthermore, the variations of shear modulus and damping ratio with shear strain amplitude are presented. In addition, the obtained dynamic properties from this study are compared with existing experimental data from the literature. It was found that the ranges of shear moduli of granulated rubber from the CTT and CSST are 278 to 2647 kPa and 85 to 2270 kPa, respectively. Moreover, the damping ratios obtained from CTT were higher than those from CSST at shear strains of less than 1%. The damping ratio of granulated rubber was also found to be independent of the vertical consolidation stress.
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Wijewickreme, Dharma, Antone Dabeet, and Peter Byrne. "Some Observations on the State of Stress in the Direct Simple Shear Test Using 3D Discrete Element Analysis." Geotechnical Testing Journal 36, no. 2 (January 2013): 20120066. http://dx.doi.org/10.1520/gtj20120066.
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Wichtmann, T., K. H. Andersen, M. A. Sjursen, and T. Berre. "Cyclic tests on high-quality undisturbed block samples of soft marine Norwegian clay." Canadian Geotechnical Journal 50, no. 4 (April 2013): 400–412. http://dx.doi.org/10.1139/cgj-2011-0390.
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The results of a study with undrained cyclic triaxial and direct simple shear (DSS) tests on high-quality undisturbed samples obtained from large blocks of a soft marine Norwegian clay are presented. Several tests with different average shear stresses, shear stress amplitudes, loading frequencies, and sample geometries have been performed on block samples taken from different depths. In tests with small average shear stresses, failure occurred due to large shear strain amplitudes, while large permanent shear strains were observed in tests with higher average shear stresses. Diagrams quantifying the undrained cyclic strength, permanent shear strain, shear strain amplitude, and permanent pore-water pressure dependent on average shear stress, shear stress amplitude, and number of cycles have been developed based on the test results. The undrained cyclic strength was found strongly dependent on loading frequency. Block samples from shallower depth showed a somewhat higher undrained cyclic strength. No influence of the height-to-diameter ratio of the samples (h/d = 1 and 2 were compared) could be found. A qualitative comparison of the test results with data for standard tube samples is provided.
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Dabeet, Antone, Dharma Wijewickreme, and Peter Byrne. "Evaluation of stress strain non-uniformities in the laboratory direct simple shear test specimens using 3D discrete element analysis." Geomechanics and Geoengineering 10, no. 4 (January 14, 2015): 249–60. http://dx.doi.org/10.1080/17486025.2014.979889.
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Tian, W. M., A. J. Silva, G. E. Veyera, and M. H. Sadd. "Drained creep of undisturbed cohesive marine sediments." Canadian Geotechnical Journal 31, no. 6 (December 1, 1994): 841–55. http://dx.doi.org/10.1139/t94-101.
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Long-term, drained triaxial creep and direct simple shear creep tests were conducted on undisturbed marine specimens from the Gulf of Mexico and the north-central Pacific. Results indicated that time-dependent deformations can be represented by a power law equation, and the creep strain rate can be represented by an equation similar to that suggested earlier by other researchers. However, it was found that the m parameter suggested by these scientists was not a constant but dependent on stress level and sediment plasticity. Ageing effects were evidenced in triaxial specimens by the increase of shear strength with both test duration and stress level. The results provided a guide for the development of mathematical stress–strain–time relationships that will be developed in a separate paper. Key words : drained triaxial creep, simple shear creep, stress–strain–time behavior.
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Vucetic, Mladen. "Normalized behavior of clay under irregular cyclic loading." Canadian Geotechnical Journal 27, no. 1 (February 1, 1990): 29–46. http://dx.doi.org/10.1139/t90-004.
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A systematic analysis of the undrained stress–strain behavior of clay under irregular cyclic simple shear loading is presented. Seven specimens of an offshore clay consolidated to overconsolidation ratios of 1, 2, and 4 were subjected to different combinations of variable and nonsymmetric cyclic amplitudes using the Norwegian Geotechnical Institute (NGI) direct simple shear device. The test results show that (1) the behavior under such loads is influenced by several different factors, (2) among these factors the loading history and cyclic stiffness degradation are predominant, and (3) the irregular cyclic loading stress–strain curves can be described quite well by five rules that incorporate only these two factors. Four out of these five rules are the extensions of two original and two extended Masing rules to the behaviour of cyclically degrading clay. The fifth rule is new. The effects of the S-shaping of the stress–strain curves and the rate of loading on the applicability of the rules are also discussed. The stress–strain curves are presented in the normalized form with respect to the vertical effective consolidation stress. In this form they show quantitatively the same trends, indicating that such normalization is applicable to irregular cyclic loading. Key words: clay, earthquake loading, laboratory test, ocean soil, overconsolidation, simple shear test, soil dynamics, strain rate effect, repeated loading.
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Moon, Sung-woo, and Youssef M. A. Hashash. "From Direct Simple Shear Test to Soil Model Development and Supported Excavation Simulation: Integrated Computational-Experimental Soil Behavior Characterization Framework." Journal of Geotechnical and Geoenvironmental Engineering 141, no. 11 (November 2015): 04015050. http://dx.doi.org/10.1061/(asce)gt.1943-5606.0001351.
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Klar, Assaf, Michael Roed, Irene Rocchi, and Ieva Paegle. "Evaluation of Horizontal Stresses in Soil during Direct Simple Shear by High-Resolution Distributed Fiber Optic Sensing." Sensors 19, no. 17 (August 24, 2019): 3684. http://dx.doi.org/10.3390/s19173684.
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This paper presents an approach for evaluating the horizontal stresses that develop in geotechnical Direct Simple Shear (DSS) tests through the use of high-resolution distributed fiber optic sensing. For this aim, fiber optics were embedded in 3D printed rings used for confining the soil in the test procedure. An analytical approach linking the measured spatially-distributed strain profile and the internal soil-ring contact stresses is developed in the paper. The method is based on representation of the contact stresses by a Fourier series expansion, and determining the coefficients of the series by minimizing the difference between the measured strain and the analytical strain within the linear elastic ring. The minimization problem results in a linear set of equations that can easily be solved for a given measurement. The approach is demonstrated on a set of drained DSS tests on clean sand specimens. Stress paths using the evaluated horizontal stresses are plotted together with Mohr circles at failure. These illustrate how, in these specific tests, the horizontal stress increases and principal stress direction rotates, until failure occurs along horizontal planes.
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Doan, Nhat-Phi, Sung-Sik Park, and Dong-Eun Lee. "Assessment of Pohang Earthquake-Induced Liquefaction at Youngil-Man Port Using the UBCSAND2 Model." Applied Sciences 10, no. 16 (August 5, 2020): 5424. http://dx.doi.org/10.3390/app10165424.
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The practical constitutive model UBCSAND2, which combines two-mobilized planes—a maximum shear stress plane and a horizontal plane within a framework of classical plasticity approach—is used to incorporate shear-induced effects in both loading and unloading as well as principal stress rotation effects. UBCSAND2 was calibrated by capturing cyclic direct simple shear (CDSS) test results of Pohang sand, which was collected from liquefied paddy fields due to the 2017 Pohang earthquake (Mw = 5.4) in South Korea. The model procedure focuses on simple shear condition because it best simulates field conditions under earthquake loading. The calibrated UBCSAND2 model is then used to assess the liquefaction-induced damages that occurred at the quay wall and backfill layer in Youngil-man port near the epicenter of the Pohang earthquake. The numerical results show that liquefaction mostly occurred in silty sand layers, in which the excess pore pressure ratio reached almost one. The estimated displacements of the quay wall and the predicted settlement of reclaimed area obtained from the analysis were in good agreement with those obtained from field measurements.
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Hsieh, Pio-Go, Chang-Yu Ou, and Hui-Tzu Liu. "Basal heave analysis of excavations with consideration of anisotropic undrained strength of clay." Canadian Geotechnical Journal 45, no. 6 (June 2008): 788–99. http://dx.doi.org/10.1139/t08-006.
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In this study, two cases of excavation to failure were utilized to investigate reasonable analysis methods for basal heave analysis. Three types of tests were carried out to obtain the undrained shear strength of clay in excavations, including the field vane (FV) shear test, the triaxial unconsolidated undrained (UU) shear test, the K0-consolidated undrained axial compression (CK0U-AC) test, the K0-consolidated undrained axial extension (CK0U-AE) test, and the K0-consolidated undrained direct simple shear (CK0U-DSS) test. The analysis results show that the safety factors against basal heave calculated using isotropic undrained strength from the UU test appear acceptable in both excavations, but the results are highly empirical. Safety factors calculated from the FV test tend to be irregular. Moreover, the safety factors were overestimated using the CK0U-AC test results. On the other hand, the safety factors computed using anisotropic undrained strength yielded reasonable results. If we perform simplified anisotropic analysis using the average value of the CK0U-AC and CK0U-AE test results or the undrained strength obtained from the CK0U-AC and CK0U-AE tests utilized in the active and passive sides of the failure surface, respectively, the results will be close to those from anisotropic undrained strength analysis but on the conservative side. Therefore, anisotropic undrained strength analysis and simplified anisotropic analysis are recommended for basal heave analysis.
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Yang, Eomzi, Tae Sup Yun, Kwang Yeom Kim, Seong Woo Moon, and Yong-Seok Seo. "Estimation of the Structural and Geomechanical Anisotropy in Fault Gouges Using 3D Micro-Computed Tomography (μ-CT)." Sensors 20, no. 17 (August 20, 2020): 4706. http://dx.doi.org/10.3390/s20174706.
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Fault gouges play an important role in the shear deformation of fault zones, by causing weakness and frictional instability in structures. Previous studies have investigated the evolution of shear deformation of fault zones by observing experiments using remolded and synthetic gouge specimens at a micro-scale. However, how the spatial configuration of the rock constituents accounts for the 3D anisotropy of intact structures of fault gouges, particularly at the core-scale, is not well understood. We obtained 3D μ-CT images of directionally cored gouge specimens and performed statistical analysis to quantify the major orientation of the internal structures. Direct shear tests were conducted to investigate the relationship between the distribution of the internal structures and geomechanical behavior. The results show that the undisturbed fault gouge has a clear anisotropy parallel to the fault plane even at the core-scale. Moreover, the direct shear test results show that the frictional resistance of a fault gouge has anisotropy related to the fault plane. The simple, yet robust method proposed in this study confirms that the core-scale structural anisotropy is correlated to the anisotropic shear resistance.
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Olson, Scott M., and Timothy D. Stark. "Use of laboratory data to confirm yield and liquefied strength ratio concepts." Canadian Geotechnical Journal 40, no. 6 (December 1, 2003): 1164–84. http://dx.doi.org/10.1139/t03-058.
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A laboratory database of triaxial compression test results was collected to examine the use of strength ratios for liquefaction analysis. Specifically, the database was used to: (i) validate the yield strength ratio concept (or yield friction angle); (ii) demonstrate the parallelism of the consolidation line and steady state line of many sandy soils; and (iii) validate the liquefied strength ratio concept. The yield strength ratio of contractive sandy soils in triaxial compression ranges from approximately 0.29 to 0.42 (corresponding to yield friction angles of 16°23°), while the yield strength ratio from flow failure case histories (which correspond approximately to direct simple shear conditions) ranges from 0.23 to 0.31 (or yield friction angles of 13°17°). As expected, the yield friction angle is greatest in triaxial compression, smaller in direct simple shear, and likely smallest in triaxial extension. The steady state line and consolidation line of many contractive sandy soils are parallel for a wide range effective stresses, steady state line slopes, fines contents, and grain sizes and shapes that are applicable to many civil engineering structures. As such, the liquefied strength ratio is a constant for many sandy soils deposited in a consistent manner. The liquefied strength ratio is inversely related to state parameter and ranges from approximately 0.02 to 0.22 in laboratory triaxial compression tests. Flow failure case histories fall near the middle of this range.Key words: liquefaction, liquefied shear strength, yield shear strength, collapse surface, steady state line, penetration resistance.
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Eigenbrod, K. D., and J. G. Locker. "Determination of friction values for the design of side slopes lined or protected with geosynthetics." Canadian Geotechnical Journal 24, no. 4 (November 1, 1987): 509–19. http://dx.doi.org/10.1139/t87-067.
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For an economic design of side slopes lined with geomembranes or protected with geotextiles, the frictional resistance at the soil–geosynthetic interface has to be known. Direct shear testing appears to be an appropriate method by which to determine these frictional resistances. As low normal stresses apply for most typical conditions along side slopes, two simple direct shear box devices were designed for tests at low normal stresses. Soil–geosynthetic interaction was tested for 4 soil types (2 clay and 2 sand types), 19 geotextiles, and 2 geomembranes. It was found that the friction between soils and geosynthetics is less than the angle of shearing resistance for the soil. The nonwoven geotextiles mobilized more than 90% of the sand friction, whereas woven geotextiles had efficiencies between 86 and 76%. For the clays, the efficiencies recorded were approximately 60% for woven geotextiles and 70% for nonwoven geotextiles. It was further observed that for granular materials the shear strength reached after repeated loading and unloading is independent of the degree of compaction. Based on the results obtained in this study and data reported in the literature, design recommendations are suggested for side slopes protected by geotextiles or lined by geomembranes. Key words: geosynthetics, frictional resistance, relative efficiency, soil–geosynthetic interface, low stress levels, direct shear test, side slopes.
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Schweizer, Jürg. "Laboratory experiments on shear failure of snow." Annals of Glaciology 26 (1998): 97–102. http://dx.doi.org/10.1017/s0260305500014634.
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Using a direct simple-shear apparatus, snow samples (115 mm in diameter, 16–18 mm in height) taken from a so-called homogeneous layer (small rounded particles, density: 290 kg m−3) were tested in a cold laboratory. Experiments were performed for strain rates between 7 × 10−6s−1and 5 × 10−3s−1at test temperatures of −5°C, −10°C and −15°C. The effects of strain rate and temperature on failure stress, failure strain, stiffness (initial tangent modulus) and toughness were studied. The transition between the ductile and brittle (sudden fracture) state of failure was found to be at about 1 × 10−3s−1for the snow types tested, independent of temperature. Stiffness proved to be the most temperature-dependent property of alpine snow. It strongly increases with decreasing temperature. Failure strain and toughness decrease with decreasing temperature. Failure stress was found to increase slightly with decreasing temperature. The effect is not very distinct but close to statistically significant and might be partly hidden by the scatter in the stress data due to variations inherent in sampling and testing.
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Amin, Benbouras. "Predicting Shear Stress Parameters in Consolidated Drained Conditions Using Artificial Intelligence Methods." Basic and Applied Sciences - Scientific Journal of King Faisal University 22, no. 1 (2021): 1–7. http://dx.doi.org/10.37575/b/sci/0069.
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Using the direct shear stress test for estimating shear stress parameters is considered to be of great importance, mainly for enhancing and strengthening soils, assessing their bearing capacity, and predicting potential risks that could bring harm to foundations. However, conducting the test in consolidated drained conditions is quite expensive and time-consuming (e.g., up to three months in consolidated clay). To our knowledge, few researchers have suggested simple models in undrained conditions to experimentally estimate these parameters. However, in large projects and slope studies, testing in consolidated drained conditions is more important because these conditions mimic reality. The current study aims to suggest a new model for estimating shear stress parameters. The reliability of the approach was tested through comparing several models of multiple regression analysis, genetic programming, and artificial neural networks. These models were tested on 98 samples of Algiers soil. The results showed the efficiency of the artificial neural network method with two hidden layers, which provided the best appropriate model, and the most approached results to experimental data, as compared with the other models. Based on these findings, this study proposes a structural flowchart for effectively predicting shear stress parameters effectively in future studies.
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Oblizajek, K. L., and A. G. Veith. "Tire Treadwear — A Comprehensive Evaluation of the Factors: Generic Type, Aspect Ratio, Tread Pattern, and Tread Composition Part IV: Laboratory Measurement of Mechanical Properties and Mechanical Actions of Tires Relating to Treadwear." Tire Science and Technology 14, no. 4 (October 1, 1986): 264–91. http://dx.doi.org/10.2346/1.2148777.
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Abstract Treadwear is explained by specific mechanical properties and actions of tires. Rubber shear stresses in the contact zone between the tire and the road become large at large slip angles. When normal stresses are insufficient to prevent sliding at the rear of the footprint, wear occurs at a rate that depends on test severity. Two experimental approaches are described to relate treadwear to tire characteristics. The first uses transducers imbedded in a simulated road surface to obtain direct measurements of contact stresses on the loaded, freely-rolling, steered tires. The second approach is developed with the aid of a simple carcass, tread-band, tread-rubber tire model. Various tire structural configurations; characterized by carcass spring rate, edgewise flexural band stiffness, and tread rubber shear stiffness; are simulated and lateral shear stress response in the contact zone is determined. Tires featuring high band stiffness and low carcass stiffness generate lower lateral shear stress levels. Furthermore, coupling of tread-rubber stiffness and band flexural rigidity are important in determining level of shear stresses. Laboratory measurements with the described apparatus produced values of tread-band bending and carcass lateral stiffness for several tire constructions. Good correlation is shown between treadwear and a broad range of tire stiffness and test course severities.
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Schweizer, Jürg. "Laboratory experiments on shear failure of snow." Annals of Glaciology 26 (1998): 97–102. http://dx.doi.org/10.3189/1998aog26-1-97-102.
Full textAbstract:
Using a direct simple-shear apparatus, snow samples (115 mm in diameter, 16–18 mm in height) taken from a so-called homogeneous layer (small rounded particles, density: 290 kg m−3) were tested in a cold laboratory. Experiments were performed for strain rates between 7 × 10−6 s−1 and 5 × 10−3 s−1 at test temperatures of −5°C, −10°C and −15°C. The effects of strain rate and temperature on failure stress, failure strain, stiffness (initial tangent modulus) and toughness were studied. The transition between the ductile and brittle (sudden fracture) state of failure was found to be at about 1 × 10−3 s−1 for the snow types tested, independent of temperature. Stiffness proved to be the most temperature-dependent property of alpine snow. It strongly increases with decreasing temperature. Failure strain and toughness decrease with decreasing temperature. Failure stress was found to increase slightly with decreasing temperature. The effect is not very distinct but close to statistically significant and might be partly hidden by the scatter in the stress data due to variations inherent in sampling and testing.
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Wang, Xiao-Ming, Hao Li, Zheng-Nan Yin, and Heng Xiao. "MULTIAXIAL STRAIN ENERGY FUNCTIONS OF RUBBERLIKE MATERIALS: AN EXPLICIT APPROACH BASED ON POLYNOMIAL INTERPOLATION." Rubber Chemistry and Technology 87, no. 1 (March 1, 2014): 168–83. http://dx.doi.org/10.5254/rct.13.86960.
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ABSTRACT We propose an explicit approach to obtaining multiaxial strain energy functions for incompressible, isotropic rubberlike materials undergoing large deformations. Via polynomial interpolation, we first obtain two one-dimensional strain energy functions separately from uniaxial data and shear data, and then, from these two, we obtain a multiaxial strain energy function by means of direct procedures based on well-designed logarithmic invariants. This multiaxial strain energy function exactly fits any given data from four benchmark tests, including uniaxial and equibiaxial extension, simple shear, plane–strain extension, and so forth. Furthermore, its predictions for biaxial stretch tests provide good accord with test data. The proposed approach is explicit in a sense without involving the usual procedures both in deriving forms of the multiaxial strain energy function and in estimating a number of unknown parameters.
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LeBoeuf, Denis. "Behaviour of a loose silty sand under static and cyclic loading conditions." E3S Web of Conferences 92 (2019): 08001. http://dx.doi.org/10.1051/e3sconf/20199208001.
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In recent years, considerable progress have been made in the study of liquefaction and flow failures with the introduction of the notion of steady-state of deformation and “collapse” envelope. These concepts are increasingly used in seismic stability analysis of slopes or embankments. However, as most of these studies were carried out on clean sands in the triaxial apparatus, one may question the general applicability of these results to practical conditions as several factors such as anisotropy, fines content, undrained strength anisotropy, boundary deformation conditions, stress history, etc. may play an important role. In this paper, the behaviour of the same soil, a loose silty sand, is compared for different loading and testing conditions: drained and undrained triaxial compression tests, drained and constant volume monotonic and cyclic direct simple shear (DSS) tests. Results allow to identify similarities and differences, in terms of undrained initial and steady-state shear strength and modes of undrained failure between triaxial and DSS test conditions and show that liquefaction in DSS cyclic tests is an instability triggered by shear failure developing once the friction corresponding to the characteristic envelope, as identified in the monotonic test, has been mobilized.
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Dahl, Karina R., Jason T. DeJong, Ross W. Boulanger, Robert Pyke, and Douglas Wahl. "Characterization of an alluvial silt and clay deposit for monotonic, cyclic, and post-cyclic behavior." Canadian Geotechnical Journal 51, no. 4 (April 2014): 432–40. http://dx.doi.org/10.1139/cgj-2013-0057.
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This paper presents a detailed characterization of the monotonic, cyclic, and post-cyclic behavior of two strata within a recent Holocene alluvial deposit of silty sand, sandy silt, silt, and clay. Stratum A is composed predominantly of very soft clay and very loose silt with plasticity indices ranging from 5 to 27, whereas stratum B is composed predominantly of very loose silty sand and sandy silt with plasticity indices ranging from 0 to 10. Characterization included in situ testing, undisturbed soil sampling and laboratory testing, and a field surcharge test section. Consolidation tests and monotonic, cyclic, and post-cyclic direct simple shear tests were used to evaluate the effects of varying the consolidation stress, consolidation stress history, and initial static shear stress ratio. The field and laboratory test data show distinct differences in behavior between the two soil strata, which can be related to their different index test characteristics. These results are compared with their respective behaviors predicted using common engineering correlations. The field and laboratory test data summarized herein contribute to the database and understanding of the monotonic, cyclic, and post-cyclic behaviors of low-plasticity fine-grained soils.
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Chen, Chi, Hailong Ma, and Bilian Yang. "In Situ Test Research on Friction Resistance of Self-Anchored Test Pile." Advances in Civil Engineering 2021 (August 14, 2021): 1–9. http://dx.doi.org/10.1155/2021/1785727.
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The traditional static load test method has been considered as the most direct and reliable method to determine the bearing capacity of single pile, but it has some disadvantages, such as inconvenient operation, laborious test, high cost, and being time-consuming. In this paper, a new type of pile testing method, self-anchored pile testing method, was proposed, and the in situ test was carried out for the first time. This method allows the upper and lower piles to provide force to each other and does not occupy other construction spaces. It had the advantages of simple operation and being economical and practical. Based on the Q-w curve, axial force distribution curve, and hyperbolic function model of load transfer, this paper studied the evolution law of friction of self-anchored test pile and the load transfer process of self-anchored test pile. The results show that the load transfer process of self-anchored pile-soil interface can be divided into three stages: elastic, elastic-plastic, and limit state. The friction of the upper and lower piles starts from the bottom of each pile and then gradually increases. The soil around the upper and lower piles gradually undergoes nonlinear deformation and shear failure, and the pile soil reaches the yield state. By analyzing the hyperbolic function model of load transfer, it shows that the hyperbolic function model can be better applied to the self-anchored test pile, which has reference value for the selection of the function model of self-anchored test pile in the future.
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Salam, Sajjad, Ming Xiao, Arash Khosravifar, Min Liew, Shimin Liu, and Jamal Rostami. "Characterization of static and dynamic geotechnical properties and behaviors of fine coal refuse." Canadian Geotechnical Journal 56, no. 12 (December 2019): 1901–16. http://dx.doi.org/10.1139/cgj-2018-0630.
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The geotechnical properties, cyclic behavior, and liquefaction resistance of in situ fine coal refuse (FCR) have not been sufficiently investigated. This paper presents the characterization of static and dynamic geotechnical properties of in situ coal slurry samples. Representative coal slurry samples were taken from two coal slurry impoundments in the Appalachian coalfields in the USA. Standard penetration tests (SPTs) were conducted. Index properties, hydraulic conductivity, shear strength, and shear stiffness of the FCR were determined. The geotechnical properties of the representative FCR were found significantly dependent on the location and depth of the samples. However, the FCR samples were classified as soft and low plasticity silty sands to sandy silts. Cyclic direct simple shear (DSS) tests were conducted on representative samples prepared using slurry deposition method to evaluate the liquefaction resistance and cyclic behavior of FCR. The cyclic stress ratio – number of cycles required for liquefaction occurrence (CSR–N) curve for FCR was established. The cyclic resistance of FCR compared well with the empirical correlations for sand-like materials, though the stress–strain behavior and pore-water pressure generation exhibited clay-like behavior. Each cyclic DSS test was followed by a static shearing to assess the post-liquefaction shear strength of the FCR. Significant decrease in shear modulus and dilative behavior were observed after liquefaction.
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Mei, Xuan, Scott M. Olson, and Youssef M. A. Hashash. "Evaluation of a simplified soil constitutive model considering implied strength and pore-water pressure generation for one-dimensional (1D) seismic site response." Canadian Geotechnical Journal 57, no. 7 (July 2020): 974–91. http://dx.doi.org/10.1139/cgj-2018-0893.
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Pore-water pressure (PWP) generation can lead to soil softening and liquefaction of sandy soils during earthquakes, with potential influence on site response and seismic design. The authors evaluated the generalized quadratic/hyperbolic (GQ/H) constitutive model, which captures small-strain stiffness, large-strain shear strength, and is coupled with a widely used cyclic strain–based PWP generation model (termed GQ/H+u). A suite of cyclic direct simple shear tests with a range of relative densities (∼30%–80%) and effective vertical stresses (∼25–200 kPa) and dynamic centrifuge tests with liquefiable sands were used to evaluate the ability of the GQ/H+u model to simulate cyclic soil behavior. Results indicate that GQ/H+u provides reasonable estimates of PWP increase during cyclic shear, with differences between measured and computed excess PWP ratios (ru) for both element and centrifuge tests generally smaller than 0.1. Computed spectral accelerations are comparable to centrifuge test measurements, with almost no bias at medium to long periods (T > 0.4 s) when the computed maximum shear strain (γmax) was smaller than the limit shear strain (γlimit). When computed ru > 0.8 and computed γmax > γlimit, spectral accelerations may be underestimated at both short and long periods as dilative behavior is not captured by GQ/H+u.
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Liu, Longqi, Xuesong Mao, Yajun Xiao, Qian Wu, Ke Tang, and Feifei Liu. "Effect of Rock Particle Content on the Mechanical Behavior of a Soil-Rock Mixture (SRM) via Large-Scale Direct Shear Test." Advances in Civil Engineering 2019 (July 3, 2019): 1–16. http://dx.doi.org/10.1155/2019/6452657.
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The mechanical strength of the landslide deposits directly affects the safety and operation of the roads in the western mountainous area of China. Therefore, the research is aimed at studying the mechanisms of a landslide deposit sample with different rock particle contents by analyzing its characteristics of the stress-strain behavior, the “jumping” phenomenon, the volumetric strain, and the shear strength parameters via a large-scale direct shear test. Stress-strain results show that stress-strain curves can be divided into 3 different stages: liner elastic stage, yielding stage, and strain-hardening stage. The shear strength of SRM behaves more like “soil” at a lower rock particle content and behaves more like “rock joints” at a higher rock particle content. Characteristics of the “jumping” phenomenon results show that the “intense jumping” stage becomes obvious with the increasing rock particle content and the normal stress. However, the lower the rock particle content is, the more obvious the “jumping” phenomenon under the same normal stress is. Volumetric strain results show that the sample with a lower rock particle content showed a dilatancy behavior under the low normal stress and shrinkage behavior under the high normal stress. The dilatancy value becomes smaller with the increasing normal stress. The maximum shear stress value of the rock particle content corresponds to the maximum value of dilatancy or shrinkage. We also conclude that the intercept of the Mohr failure envelope of the soil-rock mixture should be called the “equivalent cohesion,” not simply called the “cohesion.” The higher the normal stress and rock particle content are, the bigger the equivalent cohesion and the internal friction angle is.
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Shang, Shouping, and Zhen Wang. "Dynamic Analysis of a Spring-Asphalt Three-Dimensional Isolation System Based on Cyclic Simple Shear and Shaking Table Tests." Applied Sciences 10, no. 18 (September 18, 2020): 6530. http://dx.doi.org/10.3390/app10186530.
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Damping is one of the important issues related to isolated structures, including the newly proposed low-cost spring-asphalt isolation system. In this study, the damping properties of the system in terms of displacement dependence, frequency dependence and temperature dependence were studied by a cyclic simple shear experiment. Then, the direct least-square method was used to identify the damping properties from the experimental data. Furthermore, to validate the effectiveness of the damping device, a modal analysis was conducted based on multi-dimensional shaking table tests. The results indicate that (1) the hysteretic curves are similar to an ellipse, which means that the asphalt shows characteristics of viscoelastic materials; (2) the damping properties are positively related to the loading frequency and inversely related to the temperature and displacement; and (3) asphalt can provide adequate damping and reduce the displacements of the superstructure by nearly half. On the basis of the experimental test results, an analysis of the modal information with multi-dimensional input is also presented.
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Ferdosi, Behnam, Michael James, and Michel Aubertin. "Numerical simulations of seismic and post-seismic behavior of tailings." Canadian Geotechnical Journal 53, no. 1 (January 2016): 85–92. http://dx.doi.org/10.1139/cgj-2014-0345.
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Several tailings impoundments have failed as a result of earthquakes in the last few decades. A majority of these failures were due to direct seismic loading, tailings liquefaction during shaking, or the post-seismic behavior of the tailings as it relates to the dissipation of excess pore-water pressures that were generated during shaking. Previous work has indicated that the UBCSAND model developed by Byrne et al. in 1995 is capable of simulating the cyclic simple shear testing response of low-plasticity tailings over a range of consolidation stresses and cyclic shear ratios. However, the ability of the model to simulate the dynamic and subsequent behavior of such tailings for other conditions, such those induced by shaking table tests, has not yet been evaluated. In this regard, previous work has shown that the main components of the UBCSAND model cannot realistically simulate some specific responses, including the post-seismic volumetric strains related to excess pore-water pressure dissipation. This paper presents numerical modeling results of the dynamic behavior of tailings from hard rock mines. It introduces a method for simulating their post-seismic behavior by including an updating scheme for the elastic moduli into the UBCSAND model. The results of cyclic simple shear testing, seismic table testing, and complementary experimental relationships were used to calibrate and validate the model with its new component. The simulated response of tailings during cyclic simple shear testing and for a complete seismic table test shows that the proposed approach simulates the experimental observations well. Level-ground, seismically induced liquefaction and post-seismic behavior of a 15 m thick tailings deposit are also simulated, leading to post-liquefaction settlements that are in agreement with empirical relationships.