Study On The Model Test And Numerical Analysis Of Slope Stability Caused By Water Drawdown

The slope instability is usually caused by the water drawdown in front of the slope which isusually caused by the river flood, dammed lake and reservoir flood discharge, ebb tide of seawater and so on. The slope instability threats people’s life and property and all kinds ofengineering safety seriously. The influence of the water drawdown in front of the slope to thestability of the slope is a complex problem that involves the change of transient unsaturatedseepage. Study the seepage and the slope stability change with the water drawdown is importantto fully understand the slope instability mechanical mechanism caused by the water drawdown.Furthermore, it has an important theoretical significance to prevent and control the slopeinstability disaster. The main study and results of the paper are as follows:1. Due to the toughened glass model box designed by ourselves, medium sand and silty claytransient unsaturated seepage and the slope instability are monitored by the sensor and hd videocamera. Water drawdown speed, fall ratio and slope angle influence to the seepage and slopestability in the process of water drawdown is discussed. In addition the influence of the changeof seepage to the stability of slope is studied.2. Based on the model tests, seepage and slope stability in different drawdown speed, fallratio and filling materials numerical simulation is carried out by use seep/w and slope/w ofGeo-slope. Different results of limit equilibrium methods used in the stability analysis of slopesis discussed. The influence of matrix suction on the unsaturated slope stability is investigated.3. For the example of slope seepage and stability in the process of water drawdown,numerical simulation is carried out by use sigma/w of Geo-slope based on the interaction ofcoupling seepage and stress unsaturated seepage, and is compared with the uncoupled results.The analysis shows is listed as follows: the difference of slope inside and outside porewater pressure caused by the water drawdown is the main mechanical mechanism that lead toslope instability; greater speed, smaller slope toe and hydraulic conductivity against the porewater pressure inside the slope dissipate; greater speed and fall ratio, lower initial water levelagainst the slope stability; matrix suction is considered in slope stability analysis lead to slopesafety factor increase; the retention pore water pressure is the main factors that cause the changeof stress and deformation field; the safety factor of coupled calculation is lower than uncoupledcalculation.