| Slope instability is one of the most common engineering geological disasters,and it causes a large number of casualties and property losses worldwide every year.Rainfall is the main external factor leading to slope instability.On the one hand,rainfall can increase the weight of the soil,weaken the shear strength of the soil,and also reduce the internal matrix suction of the soil,leading to a decrease in slope stability.On the other hand,different rainfall processes have different impacts on slope stability.Therefore,conducting research on the mechanism and reliability of slope instability considering rainfall processes is of great significance for the risk assessment and prevention of slope instability disasters.At present,there are the following shortcomings in the research on the mechanism and reliability of slope instability caused by rainfall processes:（1）there is relatively little research on the impact of rainfall processes on slope reliability;（2）How to simulate the random characteristics of rainfall processes based on a small amount of rainfall data and predict slope reliability under future rainfall effects.In response to the above shortcomings,this article conducted research on the mechanism,reliability analysis,and prediction of slope instability considering rainfall processes.The main research work is as follows:（1）Summarized the research progress on slope reliability under rainfall infiltration conditions both domestically and internationally,reviewed the current status of slope reliability research under a single rainfall process,and pointed out the shortcomings of slope instability mechanism and reliability research induced by a single rainfall process.A Green-Ampt slope infiltration model suitable for different rainfall processes has been developed,revealing the impact of different rainfall processes on slope stability.Research shows that the rate of change in safety coefficient during incremental rainfal l is the highest,and it has the greatest impact on slope stability under long-term rainfall conditions;The decreasing rainfall process has the greatest impact on slope stability in the early stages of rainfall;Considering the slope stability during the entire rainfall process,the uniform rainfall process has the greatest impact on the slope stability.（2）A time-dependent reliability analysis method for unsaturated slopes was proposed,which can consider the randomness of rainfall process and the variability of soil parameters.The calculation program was written using MATLAB language.The proposed method not only has analytical solutions and high efficiency in solving slope reliability problems considering the random characteristics of rainfall processes,but also provides an effective solution for low probability(10-6-10-4)horizontal slope reliability analysis.analysis method for unsaturated slopes considering the randomness of rainfall processes and the variability of soil parameters is proposed,and a calculation program is written using MATLAB language.The proposed method not only has an analytical solution,which is highly efficient in solving slope reliability problems considering the stochastic characteristics of rainfall processes,but also provides an effective solution for reliability analysis of low probability（10-6 to 10-4）horizontal slopes.（3）In order to explore the mechanism of slope instability under rainfall,the influence of average rainfall intensity and saturated permeability coefficient on the mechanism and reliability of slope instability was investigated.It was found that as the saturated permeability coefficient increased,the probability of slope failure gradually decreased with the increase of saturated permeability coefficient during the continuous period of early rainfall.Once the randomness of the rainfall process is considered,the distribution of slope safety factors becomes wider,and there is a possibility of instability of the slope in the early stage of rainfall.However,as the average rainfall intensity gradually increases,the difference in slope reliability under uniform rainfall and random rainfall processes gradually decreases.（4）A method has been developed to derive bounded random cascade model parameters based on a small amount of rainfall duration data.This method can use a small amount of rainfall data to calibrate model parameters,expand rainfall time series,and predict slope failure probability.This provides an important basis for the risk assessment and prevention of slope instability.Research has shown that the predicted random rainfall process is similar to the actual rainfall process;There is a significant error in predicting the probability of slope failure solely considering the rainfall process,and the variability of soil parameters is also an urgent need to consider part... |
