Research On Stability Of Collapse Body Landslide Base On Saturated And Unsaturated Seepage Flow Theory

Fengxi port landslide is influenced by the rain, rivers and the influence of rapid drawdown. Fengxi port landslide belongs to secondary deposit whose material composition is soil and broken rock mass, the structure is soft and broken, the bonding force between particles is poor, and has strong permeability, so the mechanical properties is easily affected by the hydrological condition. Long time of rainfall and rapid drawdown has had a huge impact on seepage field of Fengxi port landslide, threatening the overall stability of the landslide. So study the stability of Fengxi port under the condition of rainfall and rapid drawdown has important significance and provide theory basis for the prevention of the landslide. This text study the change rule of slope seepage field under the condition of rainfall infiltration and rapid drawdown base on the theory of saturated-unsaturated seepage flow, getting the change rule of the pore water pressure of the slop, then using the limit equilibrium method to analyze the slope stability. This text mainly study the landslide stability under the condition of rainfall intensity, rainfall duration and rapid drawdown. This article has made the following research:(1) The greater the rainfall intensity, the more the rainwater infiltrate into the landslide per unit time, the greater the change of pore water pressure in the landslide. After three days, when the rainfall intensity is 0.0003m/h,0.0015m/h,0.006m/h, the safety factor of landslide reduce 5%,17.4%,20% respectively. When the rainfall intensity is greater than the permeability coefficient of the landslide, the landslide of Fengxi port will occur landslide disaster within three days.(2) The longer the rainfall duration, the greater the change of pore water pressure, the higher the water level rise. When the rainfall intensity is 0.0015m/h, the rainfall duration for 2 day,3days,4days, the safety factor of landslide reduce to 1.022,0.958,0.917 respectively, reduce 11.9%,17.4%,21% respectively. When the rainfall intensity is 0.0015m/d,0.006m/h, the landslide disaster occurs in 54 hours and 42 hours respectively.(3) The rain drawdown can course lag pore water pressure in landslide, the faster the water level drop, the slower the pore water pressure dissipate, the greater the seepage force in the landslide, the poorer the stability of the landslide. When the fall speed of water level is 0.1m/d,0.4m/d,2m/d, the reduction of the landslide safety coefficient is 24%,31%,35% respectively. When the drop speed of the water level is more than 0.4m/d, there is a possibility of a landslide hazard for the landslide of Fengxi port.(4) The higher the initial water level, the longer the time needed for drops to a stable water level, the greater the penetration is, the greater the adverse to the stability of the landslide. When the initial water level height is 20m,15m,10m, the saturation line fell by 16m,14m, llm respectively, reduce 49%,35%,12% respectively, and occurs landslide disaster on the eighth day, forth day, third day respectively.