Research On The Slope Stability Of Langjia Reservoir Qinghai

Slope stability assessments are conventional problems for geotechnical engineers.The predictions of slope stability in soil or rock masses play a vital role when designing for dams,roads,tunnels,excavations,open pit mines,and other engineering structures.This study introduces rock slope stability analysis and the purpose of such analysis serves in the investigation of potential slope failure mechanisms.Dam construction for hydropower development is a very important subject matter all around the world,especially in developing countries facing energy crises.Filling of reservoir lakes may trigger or re-activate landslides in reservoir area.Therefore,the primary objective of this study is to conduct slope stability analysis of Profile A-A’ of slope 1,Profile 2 and Profile 3 of slope 2 and slope 3 of the left bank of the Langjia reservoir,Qinghai province China.In the assessment of slopes,the factor of safety values remains the primary index for determining how close or how far slopes are from the failure point.For evaluating factor of safety coefficient,SLOPE/W module of Geo Studio software was used for two-dimensional slope stability analysis of Profile A-A’,Profile 2 and Profile 3 based on the Bishop method and Morgenstern-Price approach of limit equilibrium method.While FLAC3 D software was used for the slope stability analysis of slope 3 based on strength reduction technique of finite difference method.Factor of safety(FS)was calculated using both aforementioned methods under different working conditions and the results were drawn.Two-dimensional slope stability analysis was performed under four different working conditions i-e(a)Natural state(b)Rainstorm condition(c)Earthquake Condition(d)Reservoir condition.The analysis results showed that in profile A-A’ the stability coefficient in natural condition were 1.204 and 1.201 and under Rainstorm condition the factor of safety calculated were 1.116 and 1.109 by Bishop method and Morgenstern-price method respectively.Similarly,in earthquake condition,the FS values were 1.041 and 1.042 and in reservoir condition,FS values were 1.055 and 1.048 by Bishop method and Morgensternprice method respectively.The FS values show that Profile A-A’ is stable in natural state and rainstorm conditions while it shows poor stability in earthquake and reservoir conditions.For Profile 2,the FS calculated in natural state was 1.067 and in rainstorm condition FS values were 0.971 and 0.967 through Bishop method and Morgenstern-Price method respectively.Under earthquake condition the factor of safety values calculated were 0.927 and after impoundment the factor of safety calculated was 0.973 and 0.970 through Bishop method and Morgenstern-Price method respectively.The factor of safety values suggest that Profile 2 stability is poor in natural state while under rainstorm,earthquake and reservoir conditions,the factor of safety calculated suggests that it is not stable.While for Profile 3,the factor of safety calculated in natural state was 1.028 and 1.010 and in rainstorm condition FS values were 0.857 and 0.844 through Bishop method and Morgenstern-Price method respectively.Under earthquake condition,the factor of safety calculated was 0.917 and 0.900 and after impoundment the FS calculated was 0.813 through Bishop method and Morgenstern-Price method.The factor of safety values suggest that Profile 3 stability in natural state is poor.While under rainstorm,earthquake and reservoir conditions,the factor of safety calculated suggests that it is not stable and susceptible for sliding under these conditions.For the slope stability analysis of slope 3 of the left bank,we used three-dimensional FLAC3 D software which is based on finite difference method and follow shear strength reduction technique in slope stability analysis.The slope stability analysis was carried out under five different working conditions i-e(a)Natural state(b)Natural state after impoundment(c)Rainstorm condition(d)Rainstorm condition after impoundment(e)Seismic condition.The analysis result showed that the stability coefficient of slope 3 was1.19 in natural condition.Similarly,the stability coefficient of reservoir condition,rainstorm,rainstorm after impoundment and earthquake condition were 1.14,1.13,1.07 and 1.00 respectively.These values suggest that the slope is stable under these conditions.