Research On Spatial Variability Of Soil Properties And Reliability Analysis Of Slope Progressive Failure

The research on reliability analysis method of slope has been developed for a long time, and one of the most important subjects is the research considering progressive failure mechanism.Firstly, this paper summarizes the four uncertainty sources of the soil parameters, in which the variability of soil properties is the most fundamental uncertainty and can not be ignored. Then the random field theory is introduced, which is used after the trend component of the test data has been eliminated by the method of least squares. Combine the improved correlation function method with the spatial recursive method to find the smooth point of the two curves to calculate the correlation distance. The result is slightly larger than that obtained only by the spatial recursive method. So is the spatial variation coefficient. Then, the expression of the coefficient of spatial variation is given out based on the previous analysis.Then, according to the different load conditions and four different stability calculating method, namely Fellenius method, simplified Bishop method, the transfer coefficient method and the strict slice method, the different safety margin expressions is derived. Based on the model of progressive failure of strain softening slope, considering the uncertainty of the two soil parameters, the reliability theory is used to establish the limit state equation of the slope progressive destruction and calculate the slope probabilities for the partial failure and the progressive failure. The mode of failure considered here is that failure initiates within an assumed slip surface in the ’weakest’ segment and progresses outwards from that segment along the slip surface, which is more realistic and general. Then the influence of the expression of safety margin on the local damage probability, the transmission path and the overall progressive failure probability is studied. The example shows that the results obtained by the transfer coefficient method are more close to the results of the strict slice method, contrast to the Fellenius method and the Bishop method.Finally, give a brief introduction to the simulation of the spatial variability of soil parameters and systematically analyze the effect of the inherent variability, correlation distance, type of correlation function and systematic uncertainty on the local damage probability and the overall probability of progressive failure to find the positon where the initial failure occurs in different soil parameter. The previous results provide practical guiding significance to take the reinforcement measures to prevent the occurrence of the progressive failure.