高水头坝基裂隙岩体渗流稳定分析

Study on Stability of Fractured Rock Mass of High Head Dam Foundation

随着我国大坝建设高度及坝前蓄水高度的增大,水库蓄水后坝基岩体面临很高的外水压力,势必影响坝基岩体中裂隙在高水头压力作用下的稳定性及渗透性,这关系着整个工程的安全性。根据前坪水库工程坝址区基岩特点,依托渗透破坏理论,通过现场钻孔压水试验结果,对坝基裂隙岩体透水率在水平、垂直等维度的分布情况及曲线类型进行了分析,说明坝址区岩体存在长期渗透破坏的风险。收集施工期坝基裂隙岩体采用的入岩钢筋混凝土防渗墙及帷幕灌浆等工程处理成果,采用数值模拟分析各介质的水力坡降、取样进行室内试验、施工后进行压水试验复核等手段,证明了工程处理措施能有效保证高水头作用下坝基裂隙岩体的稳定,确保了运营期坝基岩体在长期渗透条件下安全稳定。

With the increase of dam construction height and the increase of water storage height in front of dam,the dam foundation rock body faces high external water pressure after reservoir impoundment,which will inevitably affect the stability of fractures in dam foundation rock under high head pressure and permeability,which is related to the safety of the entire project.According to the characteristics of bedrock in the dam site area of Qianping Reservoir Project,relying on the theory of seepage failure,through the results of on?site drilling water test,the distribution of water permeability of dam foundation fractures in horizontal and vertical dimensions and its curve types were analyzed,indica?ting the risk of long?term infiltration damage in the rock mass at the dam site.The results of engineering treatments such as reinforced con?crete anti?seepage wall and curtain grouting used in dam foundation fractured rock mass during construction period were collected.Numerical simulation was used to analyze the hydraulic gradient of each medium,indoor sampling test and post?construction water pressure test review.The engineering treatment measures could effectively control the stability of the dam foundation fractured rock mass under the action of high water head and ensured the safety and stability of the dam foundation rock mass under long?term penetration conditions during the operation period.