Analysis Of Precipitation Infiltration Unsaturated Seepage In Landslide Of Kumua Section In Ludila Hydropower Station

Landslide caused by slope destabilization is one of the worldwide geologicaldisasters, and pose great hazard on human society and economic construction.Rainfall is the most important and common factor causing slope stability decliningand failure of landslide.70%landslide cases were caused by rainfall, and95%of thathappened in rainy season. Analyzing the effect of precipitation infiltration on slopeunderwater level and saturated ratio therefore is an important part of the research onslope stability.At the beginning of this thesis, the basic concepts about unsaturated seepage,differential equations and saturated-unsaturated seepage FEM are introduced.Secondarily, considering an ideal soil slope model as the analyzing object, the effectof parameters： rainfall, coefficient of permeability, matric suction, soil-watercharacteristic curve—curve relationship between coefficient of permeability andmatric suction, volumetric moisture content and matric suction—are studied. Thephreatic line in raining condition presents as single-line or double-line. The type ofphreatic line is a function with soil coefficient of permeability, rainfall, rainingduration, void ratio, matric suction and geometric dimension of the slope as itsvariables. With low rainfall, big coefficient of permeability, short raining duration,small matric suction, and low slope height the phreatic line tends to be a single-line.Conversely, it tends to be a double-line. Then, as in the case of the KuMu landslidezone A in LuDila hydraulic power station, the engineering geological conditions, theform and scale of the landslide, features of deformation and failure of the landslideand its formation mechanism are analyzed. Based on the forward research, using thenatural stable water level in the landslide section as the criteria and the parametersprovided by the design parameters for the initial, the unsaturated soil mechanicalparameters for KuMu landslide zone A are identified, which include matricsuction-degree of saturation and degree of saturation-relative coefficient ofpermeability relationship. Original underwater level distribution in the landslide thenis discussed on the basis of identified parameters. Variation laws of underwater levelin the landslide, moisture content in the unsaturated section, and pore water pressureare analyzed under the conditions that whether the natural river level and normalstorage level are controlled by seepage controlling measures—discharge tunnels andupwards drain holes—or not. It is pointed out that the slope is unstable and engineering treatments should be adopted. Treatments that discharge tunnels andupwards drain holes are effective. For although the great saturation and water contentdecreases, but for reducing non-saturated zone of saturation and water content islimited.