The uniaxial compressive tests on frozen loess with different ice content under loading rate of 1.25mm/min at-6°C are carried out to investigate the effects of ice content on the mechanical behavior of ice. The influence of ice content on stress-strain, elastic modulus, strength and failure strain of frozen loess are analyzed based on the experimental data. The results show that strength and failure strain increase with increasing of ice content. The elastic modulus first increase and then decrease with increasing of ice content.
To model the stress-strain relation of frozen soil under different temperatures, an elasto-plastic constitutive model coupling with temperature variable was proposed. Under axisymmetric condition, elastic strain was calculated by the K-G model coupling with temperature. The plastic strain was calculated by using the DP yield criterion, associated flow rule and isotropic hardening law. All of the elastic and plastic parameters are related to the temperature variable. The simulated results show that the proposed model can predict the deformation behavior of frozen soil under different temperatures.
A series of triaxial compression tests on an artificial ice with strain rate of 1.67×10-4/s at-6°C are carried out to investigate the mechanical behavior of ice. The influence of confining pressure on deformation and strength characteristics of ice is analyzed based on the experimental results. The results show that the stress-strain behavior and the strength of ice changes with increasing pressure in two distinct phases.
With the rapid development of process of industrialization in Inner Mongolia, the environmental pollution, such as phenomenon of regional acid rain is gradually increasing. The Quaternary loess spread widely in Inner Mongolia. The ecological environment must be affected the intrusion acid rain. Meanwhile the physical-mechanical properties of original loess also are significantly influenced by the acid rain. To investigate the influence of acid rain on the physical-mechanical properties of loess, a series of triaxial tests in laboratory are carried out. The results showed that changes of PH value has significant effect on the specific gravity of soil grain, the limit moisture content , maximum dry density, and strength characteristics of loess.
The work condition of the highway, which is usually built in mountainous regions, is complex relative to the ordinary road. Slope instability accident caused by the seepage of rainwater usually occurred in the rainy season. The mechanism for seepage failure of slope was investigated by used the Mohr-Coulomb criterion and the principle of effective stress. The effect of rain intensity on slope stability was equivalently instead by the effect of moisture content on slope stability. The influence of moisture content on the safety factor of slope stability was further calculated according to the Bishop’s method. The degeneration of safety factor follow to the moisture content was presented in the percentage.
Abstract. Complicated geological conditions and high level ground stress are often encountered with challenges in the construction of underground caverns. It is a key problem to ensure the stability of surrounding rock during construction and operation. The numerical method can be used to simulate and predict the actual situation, to evaluate the feasibility and safety of the excavation and reinforcement scheme, and to provide the optimization suggestion and reduce the engineering risk. An underground pumping station of a water diversion project as a case study, using numerical inversion of in-situ stress, and analysis plastic volume and key points of displacement are conducted and compared under the supporting and no supporting cases, predicting the rock stability during the excavation process and providing some suggestions respectively for engineering design.
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