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高土石坝在施工期心墙会产生超静孔隙水压力,且难以有效消散,蓄水后心墙从非稳定渗流状态到稳定渗流状态,因此,渗流特性异常复杂。目前,有限元方法进行渗流计算不能考虑施工期引起的孔隙水压力,因而不能完全了解土石坝的渗流特性。长河坝为砾石土心墙堆石坝,最大坝高为240 m。利用离心模型试验技术,通过分析长河坝施工期和运行期心墙的孔隙水压力的产生和消散变化规律研究大坝心墙的渗流特性。试验结果表明,心墙孔隙水压力经历施工时的增长期、竣工后的消散期、非稳定渗流时的增长期和消散期、稳定渗流时的稳定期5个阶段。心墙高程不同、填筑含水率不同,各阶段的孔隙水压力和历时也不同。心墙位置越高或填筑含水率越大,施工期孔隙水压力系数越大,形成稳定渗流所需时间越短。心墙位置越高或填筑含水率越小,心墙位势越大,非稳定渗流期心墙位势大于稳定渗流期。研究成果对高心墙堆石坝设计和施工具有指导意义。
The high earth-rockfill dam will generate excess pore water pressure during the construction period, which is difficult to effectively dissipate. After the impoundment, the core wall changes from unsteady seepage state to steady seepage state, so the seepage flow characteristics are extremely complicated. At present, the seepage calculation by finite element method can not consider the pore water pressure caused by construction, and therefore can not fully understand the seepage characteristics of earth-rock dam. Changhe dam is a gravel soil core rockfill dam with a maximum dam height of 240 m. Centrifugal model test technique was used to study the seepage characteristics of the dam core wall by analyzing the generation and dissipation of pore water pressure during the construction and operation of the Changhe Dam. The experimental results show that the pore water pressure of the core wall experiences five stages of growth period, dissipation period after completion, growth period and dissipation period of unsteady seepage, and stability period of steady seepage. Different core wall elevation, filling different water content, pore water pressure and duration of each stage are also different. The higher the position of the core wall or the larger the water content of filling, the greater the pore water pressure coefficient during construction, the shorter the time required to form a stable seepage flow. The higher the location of the heart wall or the smaller the water content of filling, the greater the potential of the heart wall, and the potential of the heart wall in the unsteady seepage period is greater than that of the steady seepage period. The research results have guiding significance for the design and construction of high-core rockfill dam.