Study On The Unload-load Response Ratio Of Debris Landslide And Its Stability Evolution

Three Gorges region of the Yangtze River is landslide geologic disaster frequently-occurring region, where debris landslide is well developed in this region. In2003, the rising of reservoir water level from135m to175m lead to the submerging of part even whole of the landslide. The stability of landslide in this region will be dramatically influenced by the seepage flow resulting from the changes of reservoir water level. Therefore, the dynamic action law of groundwater in debris landslide and the stability evaluation are a complicated theoretical and application subject.Selecting the Three Gorges reservoir region as the research background, supported by "The survey and prevention project of geological disasters (the third stage) in the Three Gorge reservoir region of the Yangtze River" and projects of the National Natural Science Foundation of China-"Responding Ratio Parameter to Loading&Unloading and Displacement Prediction of the Debris Landslides (Code No:40672182)" and "Dynamic Parameter to Displacement Vector Angle and Displacement Intergrated Forecast in polyphyletic Information of the Debris Landslides (Code No:40872184)", and the Open Fund China Institute of Water Resources and Hydropower Research-"The Complex Dynamic Characteristics of the Water Environment in Reservoir Bank Landslide of Three Gorges Water Conservancy Project (Code No:IWHRKF201019)", selecting Bazimen landslide in the Three Gorge reservoir region as the example, the thesis has carried out a study on the dynamic response of the debris landslide by means of the numerical simulation software-GeoStudio. Finally, applying Unload-Load Response Ratio theory analyze the action law of groundwater in debris landslide, some results are summarized as follows:1. On the basis of systematical analysis geological investigation and basic geology data on the typical debris landslide in the Three Gorges reservoir, the basic features and dynamic features of debris landslide are summarized.2. On the basis of the systematical analysis of rainfall distribution law and the reservoir water storage, finding rainfall and the changing of reservoir water level are the main induced factors to groundwater changes. The action law of groundwater in debris landslide stability also is analyzed.3. By means of non-linear Unload-Load Response Ratio theory to the prediction of debris landslide, the feasibility of using groundwater changes as unload-load dynamic parameter is discussed, so unload-load dynamic parameter, unload-load dynamic response parameter and Unload-Load Response Ratio are determined.4. In terms of numerical simulation and saturated&non-saturated seepage theory, dynamic function of groundwater in debris slope, groundwater seepage distribution law are simulated, stress field and displacement field distribution law of coupled seepage field self gravity stress field are also simulated. In the ideal debris landslide model, stability coefficients of landslide is increased as reservoir water ascended, stability coefficients is decreased as reservoir water descended in typical debris landslide.5. Groundwater changes is selected as unload-load dynamic parameter, displacement changes, velocity changes and acceleration changes are selected as unload-load dynamic response parameters, so unload-load dynamic parameter, unload-load dynamic response parameter and Unload-Load Response Ratio are determined. The correlation between Unload-Load Response Ratio and slope stability is studied, some conclusion can be drawn as follows:If Unload-Load Response Ratio is1or fluctuated near1, slope is in stable stage; if response ratio is below1and last for a period, slope is transformed to unstable; if response ratio is much less than1, and tends to0, slope is about to losing stability.6. Finally, this thesis take typical debris landslide-Bazimen Landslide in Zigui County Hubei Province as the example, Calculating stability results in this thesis coincident with Unload-Load Response Ratio calculate elevation results using practical monitoring data. The effective of Unload-Load Response Ratio theory in debris landslide prediction have been verified further.