Analysis Methods For Slope Stability And Prediction For Landslide Intensity

Landslide is a widespread hazard in many mountainous and hilly regions in China. They often cause devastating economic losses as well as human victims. Obviously, landslide is an important chain in social public security. It is worthy for researchers to study about the methods for evaluating slope stability and forecasting and warning landslide. The individual slope is the direct object which should be dealed with in the actual problem. It is necessary to study the slope stability and how the unstable slope slide in further.In this thesis, the individual slope analysis is focused on the occurrence and the development of landslides hazard. The objective is to establish an integrated slope analysis system which not only includes the traditional evaluation of slope stability, but also the simulation of slope movement profile. And we want to develop an analysis tool to assess the hazard for the unstable slope. Thus the contents not only include the stability analysis problems before sliding (whether or not the slope will slide and how large the probability is to slide), but also include forecasting and warning problems if the slope will failure (the scale, the sliding velocity and distance).The slope stability methods used are based on limited equilibrium method. The efficiency and effection of searching numbers of the searching skills for critical slip surface are studied. And the precision and effection of sample numbers for reliability calculations are discussed.The slope stability issues concerning rainfall induced slope failures are presented in detail. Two different types of infiltration—U-infiltration and S-infiltration, two different failure modes of landslides due to rainfall—shallow landslides and existing critical landslides are summarized. The main ways of rainfall action to influence slope stability—1) the decrease of shear strength, 2) the increase of bulk density , 3) the increase of algebraic values of pore water pressure (matrix suction decrease and positive pore-water pressure increase) and 4) seepage forces caused by hydraulic gradient are analyzed. Finally, a simplified method combined with Mein-Larson infiltration model is given.Also, the seriate and transformative block motion theory for high speed and long distance landslide is extended and applied to forecast the profile of general slope after slide.Finally, an integrated analysis system is set up for general slope. It includes the stability analysis, the reliability calculation and the movement simulation. And also the computer code using Visual C++ program language is completed and checked. With the help of the program, some examples about the calculation of safety factor, the searching skills of critical slip surfaces, the reliability and probability of slope stability, the analysis of rainfall actions and the movement simulation are given.