大华桥水电站拉古滑坡稳定性分析研究

Stability analysis of Lagu Landslide at Dahuaqiao Hydropower Station

大华桥水电站为澜沧江上游第六梯级,地质和水文条件复杂,且分布有多处大型滑坡体,距离枢纽和居民区较近,水库蓄水后滑坡体出现不同程度的滑移迹象。本文以拉古滑坡为研究对象,在进行前期地质勘察的基础上,利用阵列式位移计和测斜仪监测分析Ⅰ区潜在滑动带,采用极限平衡法中的下限解法对该滑坡体在蓄水前和蓄水后的稳定性进行了计算。研究结果表明:滑坡体I区中部沿覆盖层局部剪出及中部至底部沿基覆界线剪出两种滑动模式安全裕度小,处于临界稳定状态,存在局部蠕滑变形的可能,与实际监测情况相符。

As the 6th-cascade in the upper reaches of Lanchangjiang River,Dahuaqiao Hydropower Station has com⁃plex geological and hydrological conditions with multiple large scale landslides distributed relatively close to the project and residential areas.After impoundment of reservoir,the landslides show signs of sliding in different de⁃grees.Taking the Lagu landslide as research object,on the basis of early geological survey,the potential sliding in zone I was monitored and analyzed with array displacement meter and inclinometer,the stability of Lagu landslide before and after impoundment was calculated by the lower limit method of limit equilibrium method.The results of study demonstrate the landslide body is cut out along the shallow surface in the middle of zone I and along the base overburden boundary from the middle to the bottom with small safety margin and in a critical stable state,and there is the possibility of local creep deformation,which is consistent with the actual monitoring situation.