Shuilin Wang

Slope stability analysis under seismic load by vector sum analysis method

Abstract The vibration characteristics and dynamic responses of rock and soil under seismic load can be estimated with dynamic finite element method (DFEM). Combining with the DFEM, the vector sum analysis method (VSAM) is employed in seismic stability analysis of a slope in this paper. Different from other conventional methods, the VSAM is proposed based on the vector characteristic of force and current stress state of the slope. The dynamic stress state of the slope at any moment under seismic load can be obtained by the DFEM, thus the factor of safety of the slope at any moment during earthquake can be easily obtained with the VSAM in consideration of the DFEM. Then, the global stability of the slope can be estimated on the basis of time-history curve of factor of safety and reliability theory. The VSAM is applied to a homogeneous slope under seismic load. The factor of safety of the slope is 1.30 under gravity only and the dynamic factor of safety under seismic load is 1.21. The calculating results show that the dynamic characteristics and stability state of the slope with input ground motion can be actually analyzed. It is believed that the VSAM is a feasible and practical approach to estimate the dynamic stability of slopes under seismic load.

Stability analysis of the Zhangmu multi-layer landslide using the vector sum method in Tibet, China

The Zhangmu landslide is located on the China–Nepal border in Tibet, China, which has recently become a serious threat to the lives and properties of local people. In order to efficiently quantify the stability of the Zhangmu landslide, a new method named the vector sum method (VSM) is proposed. Differing from conventional slope-stability analysis methods, the VSM considers both the magnitude, the direction of force and the strength-reserving definition of the safety factor based on the actual stress field of slope achieved from finite element analysis. Moreover, the global sliding direction of potential landslides was theoretically deduced by the principle of minimum potential energy, while the safety factor can be directly computed by not only the force limit equilibrium of the whole sliding body in the global sliding direction but also the moment limit equilibrium at the moment center. Finally, stability analysis of the Zhangmu landslide was performed by the proposed method, and verified against the rigorous Morgenstern–Price method.

Rupture and mechanics behavior of sandstone affected by medium strain rate

Taking sandstone as object, a virtual specimen and uniaxial compression test of sandstone was conducted under particle flow code with its embedded fish language according to the experimental results of sandstones grain analysis, compression strength, tensile strength and its cohesion or friction angle tests. The uniaixal compression tests with seven kinds of strain rate such as 10-3, 510-3, 10-2, 210-2, 510-2, 10-2, 210-2 s-2 were designed to analyze the effect of strain rate. The influences of rupture process, crack number and propagation, curve of stress and strain, energy transformation derived from strain rate were analyzed. Results show that the increase of strain rate ruins the advantageous shear zones development, which makes the shear zone expand with the same velocity, and the material failure plane changes from shearing failure to cone breakage. The strain rate meso-enhances the material mechanics and deformation features with the uplifting of stress-strain curves slope and peak value. Total cracks increase with the decreasing tensile crack and the increasing shearing crack. The boundary energy enhances, so the friction energy, kinetic energy and strain energy monotonically increase, which illustrates the increase of shear crack, violent failure and rockburst of side.