The Simulation Experiment Study Of Soil Landslides Critical Point

On the basis of the comprehensive analysis of domestic and foreign soil landslide test, rainfall landslide test, slope stability test, etc., this thesis defines the existing problem on the soil landslides study, provides evidence for the analysis of soil landslides theory and soil landslides prevention and cure, starts "The study of soil landslide critical point’s simulation experiment" that combined with the characteristics of Hunan province’s general slope soil. The main content of the study includes the invention of the soil landslide critical point test equipment, the development of soil landslide critical point test, the study of slope soil’s physical characteristics. The thesis enriches the study of soil landslides’ sliding mechanism, and has important practical and theoretical significance on the prevention and cure of the soil landslides.Taking factors such as soil moisture content, bulk density, underlying surface, mechanical composition that affect the landslide critical point into account, we carried on landslides critical point experiments for280times.The main study results are as follows,(1) The main influence of slope water film to the soil landslide could be explained from slope water film’s three function of softening, weight gain and lubricating to soil. After slope water seeps into the soil, it reduces the join forces between soil particles, increasing slope soil’s weight; Slope water seeping into the slope soil decreases the roughness between the soil particles and increases the ability of mutual dislocation, which increasing the possibility of soil landslides.(2) The main influence of the initial amount of water to critical slope is:when the other conditions are certain, with the initial amount of water gradually increasing from200ml to350ml, the water content of the soil contact surface increases, the critical slope also increases. While the initial amount of water increasing from350ml to400ml, the water content of the soil contact surface reaches its optimum moisture content, the critical slope decreases thereupon.(3) The main influence of the underlying surface to critical slope is: when the other conditions are certain, the rougher the underlying surface is, the bigger the critical slope will be. Friction are related to the roughness of contact surface and positive pressure, it’s not simply determined by the degree of the roughness, we cannot ignore the positive pressure.(4) The main influence of bulk density to critical slope is:when the soil bulk density ranges between1.30g/cm3-1.27g/cm3, critical slope changes little; when the soil bulk density ranges between1.20g/cm3-1.22g/cm3, the critical slope increases, when ranges between1.22g/cm3-1.27g/cm3, the critical slope decreases.(5) The main influence of mechanical composition to critical slope is: under the same conditions, soil sample A’s critical slope is smaller than soil sample B. In another words, under the same conditions, the clay soil’s critical slope is larger, while sandy soil’s sliding critical slope is larger.(6) The main influence of subsoil moisture content to critical slope is: the slope water film may also have some influence on the landslide critical slope; landslide critical slope has non-monotonic relationship with moisture, underlying surface material, mechanical composition, and it has coupling non-linear relationship with these factors.