古水水电站争岗滑坡堆积体方量多达4750多万m^3,为世界少有的大型滑坡堆积体。针对工程地质条件的特殊性,研究了滑坡体形成机理和失稳破坏模式;底滑面确定的基础上依据降雨过后变形区域失稳破坏过程,提出剖面随机组合法反演分析,与现场勘测、室内试验结果及类似工程经验取值进行对比,寻找出合理的计算参数;在此基础上进行稳定性评价,得知滑坡体正常工况下处于蠕滑变形状态,各种工况下均存在滑塌的可能性,必须进行开挖加固治理;根据不同的失稳破坏模式,将其分为Ⅰ区、Ⅱ区,研究了多种治理方案,推导出抗滑桩作用下滑面安全系数表达式,通过对比、优化,寻求出经济合理的综合治理措施;结果表明,治理后不仅局部稳定性得到了提升,整体稳定性也得到保证。
The volume of Zhenggang landslide accumulation mass in Gushui Hydropower Station is more than 47500000 m3,which is one of the rarely largest landslide accumulation bodies in the world.According to the speciality of the geological engineering conditions of the accumulation body,the formation mechanism and instability mode in the future of the landslide is studied.When the slip surface on the bottom is determined,a section random combination method in back analysis towards the unstable failure process of the deformation regions after raining is proposed.The analytic results are compared with those of site investigation,laboratory experiment and other similar projects so as to find out reasonable calculation parameters.The stable analysis of the accumulation mass is conducted,and it shows that the accumulation mass is in the state of creep deformation under the normal conditons and possibly slumps under any conditon,so the treatment such as excavation and reinforcement is needed.Due to the differences among the unstable failure modes of side slopes,Zhenggang landslide accumulation mass is divided into Region I and Region Ⅱ.Various treatment schemes are proposed,and a safety factor formula of slip surface under anti-slide piles is deduced.After comparison and optimization,the best economic and reasonable treatment scheme is chosen.It shows that the treatment of the accumulation mass can increase local stability and ensure the whole stability.