Advanced Materials Research Vols. 594-597

Abstract: A new technique namely modified secant modulus method（MSMM）considering time factor for nonlinear settlement computation of foundation is proposed. The principle of MSMM is using correction technique of reverse solution to solve modified secant modulus (MSM) of subsoil under different additional stress level with load-settlement test data, and the additional stress is solved with Boussinesq elasticity theory, then layer wise summation method is adopt to calculate the total settlement of foundation. The loading test results of footings performed by Briaud and Gibbens (1993) on sand foundation are analyzed with MSMM. Normalized settlement curves over width versus pressure for all footings can be obtained in normalization processing, and the calculation curve agrees well with the normalization curves. The loads of Q25 and Q150 corresponding to the settlements of 25mm and 150mm respectively of different size footings are calculated and the errors of them are within 10% compared with testing results, and the creep exponents of 3m south and north footing for 30 minutes load test were 0.036 and 0.030, then the calculated total settlement in 2014 (20 years later) will be 39.6 and 36.7mm respectively.

Abstract: On the basis of the Dynamic Relaxation method, a nonlinear finite element method (FEM) analysis procedure was developed for the geosynthetic-reinforced soil retaining wall. The FEM procedure technique incorporated the unified three-component elasto-viscoplastic constitutive model which can consider the rate-dependent behavior of both the backfill soil and the geosynthitic reinforcement. A simulation was performed on a physical model test on geosynthetic-reinforced soil retaining wall to validate the presented FEM. Extensive finite-element analyses were carried out to investigate the earth pressure distributions from the back of retaining wall under variable rate loading. It is shown that this FEM can well simulate the rate-dependent behavior and the earth pressure of geosynthetic-reinforced soil retaining wall.

Abstract: Body size of unstable rock and the impact scope of disasters are simply presented in Duba elementary school in Beichuan county, Sichuan, China. Based on the disaster’s nature, developmental history and characteristics of destruction, the law of disasters such as the movement mechanism, catastrophic failure modes, have been studied. The stability of post-earthquake unstable rock is analyzed and evaluated, and such the disaster prevention principles against unstable rock are advanced.

Abstract: Although DJM-Pile have a good effect on strengthening soft foundation,theories about additional stress are too complex or too simply to be used in project well.By adopting FEM software with considering of friction between soil and pile,simulate the additional stress in composite foundation because of DJM pile construction and compare with results gotten in Bossinesq method.The comparison shows that the distribution of additional stress is very similar.So considering several major influential factors,the paper updates the Bossinesq method and brings forward a simplified calculation method.

Abstract: In order to analyze the damage mechanism of the reinforced concrete stabilizing pile, this article studies the seismic deformation of a reinforced slope without groundwater. Then, the breaking mechanism of stabilizing pile is studied by using dynamic finite element method. The results show that the slope deformation caused by the earthquake leads to the obvious increase of dynamic bending moments, and the bending moments eventually go beyond the ultimate strength moment of the reinforced concrete piles.

Abstract: Foundation pit excavation beside silt soil railway subgrade in the water net plain district is influenced by overload of backfilled roadbed, train's vibrating load and high groundwater level, so foundation pit instability occurs easily. Numerical simulation is done on several parameters such as different depths of pit cutting, distances from subgrade, speeds of the train, and so on. Through analyzing changes and impact ranges of the pore pressure and displacement under various work conditions, it reveals lateral deformation mechanism of the foundation pit. And also it provides references for supporting design of foundation pit beside silt soil subgrade.

Abstract: Generally surrounding rocks of deep mine show the typical creep characteristics and the multi stage loading creep test of coal was carried out by MTS815 rock mechanical test system in this paper. Compared to the creep coefficient of other rocks, creep coefficient of coal is relatively small. Coal creep failure changes obviously when load level is higher than the threshold stress. The constitutive characteristics of creep failure of coal can be fitted preferably by the Cubic Polynomial.

Abstract: The ground penetrating radar can be used in the inspection of the gravel pile composite foundation, and we can make a qualitative analysis of the gravel pile integrity. The technique has the advantages of rapid, accurate and real-time processing and display especially available to collect continuously high-resolution sections of underground pile. The results showed that GPR technology will provide amount of detailed and reliable information to the engineering quality inspection of composite foundation.

Abstract: Tailings dam is a potential risk source in the metal mines, once the tailings dam break, it will not only lead to tremendous loss in people’s lives and property, but also result in serious environmental pollution. Basing on the accidents of tailings dam failure at home, the dam failure causes are analyzed, some technology and management suggestions about decreasing dam-break accident are put forward, which provide reference for safety management to tailings dam.

Abstract: To study the gradual deformation and fracture mechanism of landslide, taking Han Jiaya landslide as the prototype, the laboratorial geo-mechanical model test with geometric similarity ratio 1:200 was carried out with several different materials to simulate corresponding rock layers and structure. By applying the digital close range photogrammetry, the deformation and fracture mechanism of the landslide under natural and excavating conditions are deeply analyzed. Comparing the results of model test with field monitoring analysis, the model test can quantitatively and qualitatively analyze the deformation and failure mechanism of the landslide by relatively accurate means. The landslide has been in good condition since this controlling engineering was completed several years ago. The study results provide an effective scientific basis for the prevention and treatment of the landslide.