| Rainfall is an important cause of the instability of landslide. Not only will rainfall infiltration increase the specific weight of landslide, but at the same time will make the groundwater table of landslide uplift, increase the pore water pressure of saturated zone,and reduce the matric suction of unsaturated zone and shearing strength. Therefore, analysis of rainfall infiltration on the stability of landslide is of agreat significance.By local geological investigations, qualitative analysis and numerical calculation analysis, this thesis made a research around seepage field of Shanquan landslide on the condition of rainfall. On the basis of the change, it will analyze the effect of rainfall events on landslide stability. What it has been done and acquired is as following:1. Shanquan landslide plane form shows a wall clock shaped, with a large posterior edge, and the width of the front direction narrows down gradually. The main sliding direction is toward 145°,in the main slide direction,the maximum length is 310 m,the slope average length about 280 m,the maximum width about 330 m,and the average width about 260 m. the scale of the mountain landslide plane is about 0.0838km2,and the average thickness of the mountain sliding plane is about 9.5m.The size of the landslide body is about 8×105m3,and it is a middle-scaled cumulate(soil) landslide.2. Shanquan landslide is a typical traction type landslide.The cause of creep deformation is the damage of the original slope stable state which caused by artificial excavation in the front of landslide, and the rainfall induced the damage.3. Study under three different rainfall condition including different rainfall intensity, different rainfall time and a whole process of the heavy rainfall, the change of Shanquan the groundwater seepage field.At the initial stage of rainfall, the rainwater gives priority to infiltration to the slope foot, and then the groundwater table lifts at the slope foot. After the rainfall, the groundwater table at the foot is delayed; The increase of rainfall intensity and rainfall time will raise the groundwater table rapidly. After a heavy rainfall, the overall changing trend of groundwater table is drop rapidly first, and then slowed down. Due to thick blocks and debris of the lower Shanquan landslide, and good permeability, rainfall rechange groundwater more receptively. Groundwater table decline fast after rain stops with no apparent hysteresis phenomenon.4. Calculate and analyze the stability of Shanquan landslide and get the change rule of the stability under different rainfall conditions under different rainfall conditions.Low rainfall intensity(≤20mm/d)with the short rainfall time has a weak influence on the stability of Shanquan landslide, but with the increase of rainfall intensity, the stability is weaker.Under the same rainfall intensity(30mm/d), the stability of the landslide is accelerated decline with the increase of rainfall duration. Under the rainstorm state, Shanquan landslide will quickly enter an unstable state. After the rain stopped, Shanquan landslide will enter a stable state about two days later. After all these, the stability of Shanquan landslide will see a slow upturn, which return to its natural state over a long time.Shanquan landslide is in a stable state in the natural state and very little rainfall inrensity(≤20mm/d)with the short rainfall time. But it will quickly enter an unstable state in the rainstorms and sustained moderate rainfall. |
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