Research On The Mechanism Of Flow Slide Of Loess Landslides

The flow slide behavior of the loess landslides induced by earthquake or irrigation is the primary reason of the loess landslides disaster. A study on the mechanism of flow slide of loess landslides has important significance. When the mechanism of flow slide of loess landslides is discussed, it can find the steady state strength (residual strength) plays a major role. The evaluation of residual strength requires a better understanding of saturated loess undrained behavior. The steady strength of saturated loess is discussed under stress-controlled undrained consolidation triaxial test. According to the test results, Steady state line of saturated loess is established. These lines can be used to analysis the mechanism of flow slide. In order to study the resistance to overturning of loess slop, numerical simulation be needed.This article takes Huaxian landslide and Xiji landslide as a background, the steady behavior of saturated loess is discussed under stress-controlled undrained consolidation triaxial test. Combined numerical simulation, the mechanism of flow slide of loess landslide is discussed. The primary contents and the research results are as follows:(1) According to the test results of stress-controlled undrained consolidation triaxial test, there are two typical stress-strain behaviors of saturated loess: steady state behavior and quasi-steady state. In majority situations, it exhibits steady state behavior. Only loose loess exhibits quasi-steady state behavior.(2) According to the test results, the physical implication of steady state friction angle and cohesive strength is reveal. Steady state line and steady state strength line of saturated loess is established. These lines can be used to analysis where the flow failure of the landslides could occur.(3) The condition of the flow failure is discussed: state condition, trigger condition, drive shear stress condition. The process of distinguish where the flow failure of the landslides could occur is generalized, and it be used on the estimation of Huaxian landslide and Xiji landslide.(4) When the landslides induced by earthquake, Steady state strength plays a major role. When the landslides induced by earthquake, peak strength plays a major role.(5) According to the above method, only the local landslide has been estimated. It needs numerical simulation to decide where the flow failure of whole landslides could occur. This paper used the Flac3D to analysis the whole landslides, and the result agrees the actual situation.