松江河电厂小山水电站导流洞出口边坡稳定性分析

THE ANALYSIS ON THE HIGHWALL STABILITY OF THE XIAOSHAN HYDROPOWER STATION PILOT OUTLET OF THE SONGJIANGHE ELECTRIC PLANT

小山水电站导流洞出口边坡其地质结构为下部中侏罗世安山岩（αＪ２），其上覆盖了第三纪末第四纪初的玄武岩（βＮ～Ｑ），两者间为不整合接触，不整合面夹有０．１～０．６ｍ厚的粘土状及碎石粘土状夹层，产状倾向河床，倾角±２５°。在上覆玄武岩层中见有高倾角的宽张裂隙带，与不整合面一起构成松动岩体，不整合面为底滑面。通过边界条件的分析和稳定计算，松动岩体的抗滑系数Ｋ＝３．１０２，边坡是稳定的。在施工过程中采取了相应的安全保护措施，导流洞出口提前２８ｍ进洞，节约挖方量６００００ｍ３，提前了工期。经三年多的施工到运行，边坡无异常变化，表明该项优化设计是可行的。

From the geological structure,the highwall of pilot outlet of the Xiaoshan hydropower station belongs to lower Mid-Jurassic andesite(αJ 2).The upper is underlain by the late Tertiary and early Quaternary basalts(β N Q ),between which,there is a discordant contact with 0.1～ 0.6m clayer or clay detritus.The occurrence of the interbeds dipped to river bed and the angle of inclination is ±25°. In the overlying basalt,there is high dip and wide tension fissure zone,which is combined with surface of unconformity which is as basal sliding face,to form loosening rock mass.Through the analysis and calculation of stability for the boundary conditions,the coefficient of anti sliding is K=3.102,showing that the highwall is stable.The safety measures were taken appropriately during construction,the pilot outlets were fulilled 28m ahead of schedule for entering intake,economized cubage of excavation of 60 000m 3 and fulilled working days ahead of schedule.It takes over three years from construction to operation.The highwall is not unusual,showing that the designing of the engineering is feasible.