初次蓄水对瀑布沟库首拉裂体影响的监测分析

Monitoring of the Influence of First Impoundment on Tension-Displaced Body in Front of Pubugou Dam

施工期监测成果表明,瀑布沟电站库首右岸拉裂变形体支护结构荷载变化正常,坡体位移较小,蓄水前处于稳定状态。初次蓄水对瀑布沟库首右岸拉裂体产生了一定程度的影响。依据蓄水期间拉裂体宏观变形现象和监测资料,运用比较法、作图法和特征值统计法等对拉裂体支护结构荷载变化和变形进行分析。在此基础上综合分析后认为:受蓄水影响较大的是强卸荷底界限以上的岩体,坡体主要的变形方式为浅表松动带蠕滑变形;坡体位移随高程增加而增加,地表累计合位移10～20 mm,最大平均位移速率为0.10 mm/d;蓄水使水位高程以下的锚索荷载产生了明显的减小,最大减小量70.0 kN。从初次蓄水后连续的监测成果分析,瀑布沟库首右岸拉裂体目前仍处于整体稳定阶段。

The monitoring results during construction indicate that the load on the supporting structure of deformable body at the right bank in front of Pubugou dam changes normally.The displacement of the slope is small,and the deformable body is stable until the first impoundment.However,the first impoundment has brought negative effect on Pubugou hydraulic project.According to the macroscopic deformation phenomena and monitoring results during impounding,and using the comparison mapping and eigenvalue statistics methods,detailed analysis is presented for the load change of supporting structure and the deformation of the deformable body.The comprehensive analysis indicates that the rock above strong unloading bottom border is influenced by the impoundment,and the main deformation is creep deformation at superficial loose zone.The displacement increases as the elevation increases,and the accumulative displacement on the ground surface reaches 10 to 20 mm,with a maximum average displacement rate amounting 0.10 mm/d.The anchor load below water level reduces obviously due to impounding,with a maximum decrease of 70.0 kN.The continuous monitoring data after the first impoundment indicates that the deformable body is still stable.