特高土石坝首次蓄水期坝基渗控监测分析评价

Analysis and evaluation of seepage control monitoring of dam foundation during first impoundment period of a ultra-high earth rock dam

水库蓄水期的坝基渗流控制效果评价是大坝安全评价的重要组成部分,总结蓄水期坝基渗流变化规律对特高土石坝工程的安全运行意义重大。以中国已建成的300 m级特高土石坝——两河口水电站砾石土心墙堆石坝为例,结合工程布置特点,利用监测成果分析、地质条件分析等手段,分析和讨论蓄水过程中的渗控监测情况,指出了相关问题和可能存在的注意事项,对渗控措施的工程效果进行了评价。首次蓄水期坝基渗流分析表明:蓄水期坝基渗压与库水位的变化存在一定相关性且相关性效应需在一定水头作用下才会显现,坝基渗压变化较库水位变化一般具有滞后性,坝基深部渗压并不一定关联反映水头或水位。相关经验可为后续类似高土石坝建设提供借鉴。

The evaluation of seepage control effect of dam foundation in the impoundment period is an important part of dam safety evaluation.It has significant meaning to summarize the seepage variation law of dam foundation during impoundment period for ensuring safe operation of ultra-high earth rock dams.Taking a 300m-level ultra-high earth-rock dam,Lianghekou Hydropower Station in China as an example,we analyzed and discussed the seepage control monitoring in the process of impoundment by analyzing the monitoring data and considering geological conditions as well as engineering layout.We ascertained the relevant problems and possible precautions and evaluated the engineering effect of seepage control measures.The result show that there is a certain correlation between the seepage pressure of dam foundation and the change of reservoir water level during the storage period,and the correlation effect only appears under the action of a certain water head.The change of seepage pressure of the dam foundation generally lags behind the change of reservoir water level.The deep seepage pressure of the dam foundation does not necessarily reflect the head or water level.The relevant experiences in this paper can provide references and ideas for subsequent similar projects.