Stability Research Of Embankment Over Sloped Weak Ground Based On Reliability

Embankment over sloped weak ground is widely distributed in the southwest region of China.Embankment sliding and ground large lateral deformation will happen because of its special engineering characteristics when building embankment over sloped weak ground. It should be pay more attention to the embankment stability to ensure design safety. But the existing stability analysis method such as the rigid body limit equilibrium method or the shear strength reduction method ignores many uncertain factors in practical engineering, so can not reflect the stability of embankment over sloped weak ground well. To solve this problem, the reliability research of embankment over sloped weak ground which is based on mathematical statistics theory was conducted to overcome the traditional deterministic analysis method disadvanges in this paper.The global minimum probability analysis method assumes that the failure probability of the most dangerous slip surface obtained by deterministic analysis is the same as the failure probability of the slope. It is not rigorous from a theoretical point of view, and we should adopt the overall slope probability analysis method. Based on vertical slice limit equilibrium method software Slide, a comparison which refers to the research findings of the geotechnical centrifuge model test of embankment over sloped weak ground between the calculation principle and results of global minimum and overall slope was carried out to summary the similarities and differences, merits and faults, applicable environment. Compare to the global minimum reliability analysis method, using overall slope reliability analysis method can make the design more conservative, but cost more time. Lastly using the overall slope reliability analysis method to find the influence principle confirmed by centrifuge test results of anti-slide pile reinforcement for embankment over sloped weak ground, and well perform the application of reliability analysis method in the research field of sloped weak ground.Usually the safety factor from traditional deterministic analyse is used to evaluate the stability of the embankment over slope weak ground, which ignore the input data random variables variability. A probabilistic slope analysis model was established based on vertical slice limit equilibrium method software Slide to account for the degree of uncertainty parameters, such as embankment and sloped weak layer’s material properties, ground water table, embankment top tension crack water level, micro-pile support properties and seismic loading. Sensitivity analysis also was carried out to indicate which input parameters may be critical to the assessment of slope stability, and which input parameters are less important. Failure mechanical on the geotechnical centrifuge model of embankment over sloped weak ground was illustrated using reliability. The reliability method can describe the stability of embankment over sloped weak ground more objectively. Engineering measures were put forward to increative the stability in practice.The Rigid Body Limit Equilibrium Method (RBLEM) and the Shear Strength Reduction Method (SSRM) have been successfully applied to the analysis of stability of embankment over sloped weak ground.But the analysis of existing studies use more certainty method, most of them don’t consider the variability of shear strength index of the embankment and the surface weak layer. Both the finite element shear strength reduction method and point estimate method (PEM) are applied in this paper. Through comparing and checking test results of geotechnical centrifuge, a numerical model of analysis is created to describe the variation of shear strength index of the embankment and the surface weak layer, and to compare the level of failure probability of embankment over horizontal weak ground and embankment over sloped weak ground, and to study the law of yield zone distribution, and tensile failure and shear failure while the embankment is filled layer by layer. Studies have shown that the geotechnical centrifuge model instability and failure mechanism of embankment over sloped weak ground can be explained by combining both shear strength reduction method and point estimation method, the law of yield zone distribution could be used to guide engineering practice guidance.The rigid body limit equilibrium method and the finite element shear strength reduction method were compared by their calculation principle and calculation results. The characteristic of Monte-Carlo simulation and Point estimation method were discussed. The combination relations of two traditional analysis methods and two sampling methods were commented and the failure probability’s influencing factors of the reliability analysis method were summarized.