Reliability Analysis Of Seismic Stability Coefficient Of Loess Slope

Reliability analysis is a commonly used analysis method in engineering design.It originates from the uncertainty of design parameters and the incompleteness of knowledge.In geotechnical engineering,due to the randomness of design parameters,reliability analysis theory and methods are widely used.Reliability analysis has become one of the hot topics in geotechnical engineering research.Due to the special structure and genesis of the loess,the physical and mechanical properties of the loess are uncertain,and the randomness of earthquakes makes the safety factor for describing the stability of the loess slope seismic.Therefore,using the theory and method of reliability analysis to give a reliable index of the loess slope under earthquakes and estimate the failure probability is of great significance for evaluating the stability of the loess slope,realizing the predetermined function of the loess slope,and designing reasonably.Based on a large number of loess landslides induced by the Haiyuan earthquake detailed field investigations and indoor geotechnical tests,the reliability analysis of loess slope seismic stability,loess slope design,and loess strength parameters were carried out.The main work and research results of inversion analysis are as follows:1.The development overview of reliability analysis theory is briefly summarized,and the basic theories of reliability analysis such as reliability,limit state and limit state equation,failure probability,reliability index,and calculation method areintroduced.The influence of uncertain factors such as rock and soil parameters,rainfall conditions and earthquake action on slope reliability is analyzed.The feasibility of using the reliable index to analyze the reliability of the loess slope seismic stability is discussed.2.Based on the field landslide survey,the geometric parameters were calculated,and the distribution range of the original slope height,slope angle,and slope angle of the landslide given.The mean,standard deviation,and coefficient of variation of each parameter were given.The slope height and the Relationship between slope angles.Through experiments and data collection,basic physical and mechanical index parameters such as the gravity,cohesion,and internal friction angle of the loess were obtained.These indexes were used for reliability analysis of the loess slope.This paper also analyzes the dynamic characteristics of the dynamic shear modulus and damping ratio of the loess when the moisture content,confining pressure,and consolidation ratio are different through dynamic tests of the loess.3.Statistical analysis of the strength parameters of the loess obtained from the test was carried out,and the approximate distribution of the parameters was checked and determined,and the parameter value range involved in the reliability analysis calculation was determined.Through orthogonal tests,a slope calculation model for reliability analysis is established.The anti-sliding and sliding forces of the slope are calculated by the pseudo-static method.Their mean and variance are calculated and substituted into the calculation formula of the reliability index.The reliability index and failure probability under different seismic acceleration conditions are presented.4.Under the determined target failure probability,the slope cutting method is considered,and the quasi-static method is used to calculate and give the design reference values of the loess slope slope height and slope angle under different seismic accelerations.Through the inversion analysis method of the strength parameters of the loess slope,the internal friction angle is taken within a known and reasonable range,and the corresponding cohesion value is obtained.The reference of the cohesion and internal friction angle under different seismic intensities is given.Combined values.5.By comprehensively considering the influence of various factors on the reliability calculation,the appropriate influencing factor parameter value is determined,and the reliability analysis calculation of the single actual survey loesslandslide example is carried out by Monte Carlo method.The results show that the reliability calculation results of the loess slope and the actual landslide Match.