Study On Features And Changes Of Load-unload Response Ratio Parameters Of Colluvial Slope Under Seepage And Stress Dynamic Coupling

This article takes the prevention and forecast of geologic disaster happens in Three Gorges region as a goal, and it bases on the fieldwork for Three Gorges region and the systems analysis on the displacement dynamic features of colluvial landslide, it considers the landslide inner seepage rules induced by rainfall and the couple of seepage and stress with the basic theories of saturated-unsaturated seepage. Finally, the rules and changes of load-unload response ratio parameters of colluvial slope under seepage and stress dynamic coupling are discussed with finite element numerical simulation ways. This paper is supported by the projects of National Natural Science Foundation of China "Load-unload responding ratio parameter and displacement dynamic prediction (code No. 40672182)", "Responding ratio feature to load & unload and displacement dynamic prediction of the colluvial landslides (code No. 40472141) " and Natural Science Foundation of Shandong Province "Non-linear dynamic prediction of slide-collapse geologic disaster (code No. Y2003E01)". The mainly research contents as summarized as follows:(1) On the basis of systematical analysis geological investigation and basic geology data on the typical colluvial landslide in the Three Gorges reservoir, the main differences between colluvial landslide and other types landslide are studied, the basic features and dynamic features of colluvial landslide are summarized by analyze the composites, slippage, groundwater, lithofacies of colluvial slope.(2) Based on the basic theories of saturated-unsaturated seepage, the influences of rainfall seep through colluvial landslide are analyzed, and the basic differential equations of porous media are given. The mechanism of rainfall seep through soil slope and the coupling of seepage and stress are expatiated, and the finite model of seepage and stress coupling are given.(3) The fundamentals and applications of nonlinear systems load-unload response ratio are introduced in this paper. The nicer positive pertinence between rainfall and displacement of landslide has been proved which based on study of colluvial landslide induced by rainfall. The possibility of regarding rainfall as load-unload dynamic parameters has been discussed, and the model and judgement of load-unload response ratio applying to colluvial landslide.(4)The numerical model simulation of seepage in colluvial landslide under diverse rainfall conditions have been simulated, with which the way of numerical simulation and unsaturated seepage theories. The simulated seepage results had been inducted into stress field of slope deadweight, and the variation rules of stress and displacement field an be drawn as follows: When the landslide on relative stable stage, the load-unload response ratio fluctuated near l; when the slope transformed to unstable, the response ratio is far off bigger than 1 accordingly; the response ratio variation rules of different slope part can mirror the variety features of colluvial landslide different part effected by seepage; meanwhile, the fluctuation of response ratio in relative stable stage effected by lunar rainfall periodic variation influence.(5) Finally, this article take typical colluvial landslide-Shuping Landslide in Zigui County Hubei Province as the example, Calculating response ratio results in this thesis coincident with load-unload response ratio calculate elevation results using practical monitoring data basically. The response ratio under longer load-unload periods, like year and half year, can reflect the periodic rules of load-unload value. The displacement dynamic features of colluvial landslide under lunar rainfall load-unload and response ratio parameters short-term variation rules can be reflected by plot out the dynamic load-unload period.