In order to improve the stability of unsaturated expansive soil slope

the method of covering the slope by geo-membrane is applied. Based on unsaturated seepage theory

a finite element program is used to analyze the wetting-drying cycles caused by rainfall and evaporation on slopes covered by geo-membrane and without geo-membrane. Numerical simulation results are used to analyze the slope stability by limit equilibrium method. It is shown that the slope covered by geo-membrane can maintain the unsaturated state for a long period. The matric suction and safety factor of slope covered by geo-membrane is obviously higher than that of without it. The method of covering the slope by geo-membrane is efficient to improve the stability of unsaturated expansive soil slope.