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Qin B.,PLA Logistical Engineering University | Chen Z.-H.,Chongqing Key Laboratory of Geomechanics and Geoenvironmental Protection | Sun F.-X.,Chongqing Key Laboratory of Geomechanics and Geoenvironmental Protection | Fang X.-W.,Chongqing Key Laboratory of Geomechanics and Geoenvironmental Protection | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The temperature effect on water retention curve under high suction is investigated experimentally and theoretically. Water retention tests are conducted on GMZ bentonite at five temperatures ranging from 20°C to 100°C. The test results show that the suction equilibrium time, the water retention capacity and the hysteresis of the water retention curve decrease with the increasing temperatures, and the water retention curves at different temperatures are almost parallel to each other. According to the thermodynamics of sorption and the Le Chatelier's principle, the water adsorption by soil is always an exothermic process, and it is an inevitable phenomenon that the water retention capacity under high suction decreases with the increasing temperatures. Assuming that the adsorption heat is independent on the temperature and the water retention curves at different temperatures are parallel, a model is established to describe the temperature effect on the water retention curve. Comparisons are made between the model predictions and the test results in this work and some literatures. Good agreement of those comparisons shows that the proposed model has the capability to cover the full suction range. Source


Chu Z.-J.,PLA Logistical Engineering University | Chu Z.-J.,Chongqing Key Laboratory of Geomechanics and Geoenvironmental Protection | Sun J.-H.,PLA Logistical Engineering University | Chen Z.-P.,PLA Logistical Engineering University | Luo W.-M.,PLA Logistical Engineering University
Chemical Engineering Transactions | Year: 2015

By using the large physical test to analyze the mechanical effects of the anti-sliding pile towards the slope, this research can analyze the displacement of the top, cut export and the moment. Besides, the changeable rule about the change of the load and the soil pressure and the destruction of slope can be observed and analyzed. The results show that, during the process, the back of the pile top began to separate with the sliding body. Behind the pile, the anchoring section where near the sliding surface also separated with the sliding bed, generating a pumping area. Loading up to the 420kN, the horizontal displacement began to increase rapidly, and when load was 480kN, the horizontal displacement in the cut export also began to grow quickly. The bending moment of the pile distributed in apparent anti-S. The maximum moment of the anti-sliding section is in the place 48cm above the sliding surface. The maximum moment of anchoring section is located under the surface about 22cm deep. The maximum moment of the anti-sliding section is bigger than the value of the anchoring. Furthermore, both the back of the anti-sliding section and the front side of anchoring section are carrying loads in tension. The maximum soil pressure in front of the anti-sliding pile is located in 70cm above the sliding surface. The maximum soil pressure of the anchoring section is near the surface, but this value is zero in the bottom of the pile. In the back of the anti-sliding pile, the maximum soil pressure is in the 40cm above the surface. The soil pressure is bigger in the anchoring section, and the value in the surface is zero. The rule of distribution of the soil pressure apparently opposites with the rule in the back of the pile. The results can provide the design and calculation of the anti-sliding single steel pile some references. Copyright © 2015, AIDIC Servizi S.r.l. Source


Zhang J.,PLA Logistical Engineering University | Zhang J.,Chongqing Key Laboratory of Geomechanics and Geoenvironmental Protection | Chen Z.,PLA Logistical Engineering University | Chen Z.,Chongqing Key Laboratory of Geomechanics and Geoenvironmental Protection
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2013

In order to analyze the influence of stress state and stress path on the generalized soil-water characteristic curve, namely generalized SWCC, using the triaxial apparatus for testing unsaturated soils, a series of triaxial shrinking tests with deviator stress and net mean stress being constant values, triaxial isotropic compression tests with deviator stress and matric suction being constant values and triaxial p-fixed consolidated drained shear tests with net mean stress and matric suction being constant values are carried out against the backfill soil of the canal slope at Aayang district of South-to-North water diversion project. The test results show that matric suction, net mean stress and deviatoric stress have significant effect on the discharge of water. The expression of improved generalized SWCC is proposed, which can take the effect of stress state and stress path on the discharge of water comprehensively into account, and the computed results using this expression are in good agreement with the test data. Source


Zhang J.-H.,PLA Logistical Engineering University | Zhang J.-H.,Chongqing Key Laboratory of Geomechanics and Geoenvironmental Protection | Chen Z.-H.,PLA Logistical Engineering University | Chen Z.-H.,Chongqing Key Laboratory of Geomechanics and Geoenvironmental Protection | And 6 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2015

In order to study the deformation rules of unsaturated soils under lateral confinement, a series of one-dimensional compression tests are carried out under controlled initial dry density and matric suction. The concepts of tangent compressibility coefficient and tangent volume compression coefficient are proposed. Results of the study indicate that the tangent compressibility coefficient and tangent volume compression coefficient decay exponentially with the increasing net vertical pressure. Based on this law, two empirical models, which can describe the variations of void ratio and vertical strain with the net vertical stress, are established. The rationality of the proposed models and their applicability to various types of unsaturated soils are verified using the test data in other literatures. The proposed models can be used to calculate the mean compressibility indexes within arbitrary pressure interval, to compute the slaking deformation of unsaturated soils due to the increase of moisture content, and also to describe the variation of void ratio with the matric suction. ©, 2014, Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering. All right reserved. Source


Zhou J.-W.,PLA Logistical Engineering University | Zhou J.-W.,Chongqing Key Laboratory of Geomechanics and Geoenvironmental Protection | Liu Y.-X.,PLA Logistical Engineering University | Liu Y.-X.,Chongqing Key Laboratory of Geomechanics and Geoenvironmental Protection | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

The mechanical response of structured soil has obvious damage effects. According to the theory of complex for geotechnical materials, structured soil can be considered as the composite material constituted by the structured phase and the damaded phase. Structured soil damage process should be the deformation energy in the structural phase transiting to the dissipated energy of damage, and damage dissipative of phase change induce structural phase change to the damage phase. Viewing from a cross-section in any direction, damage resulting in the surface of structured phase into damage one. Based on this understanding, the damage variable is linking to cross-section areas of structured phase and damage phase is consistent with that of the damage variable in the classical continuum damage mechanics. The external force damage power is defined as damage dissipation energy, and introduced into the soil energy balance equation. For a typical unit of energy, a damage evolution equation is derived based on the energy consumption under the conditions of structural damage, and the determination method is provided for the model parameters. Finally, the comparison of test results and that of this model show that the proposed model can reflect the evolution of soil damage properly. Source

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