高土石坝粘土心墙和复合土工膜防渗性能研究

高土石坝在静力情况下的应力、变形特性和防渗性能一直是高土石坝设计和施工的关键问题。以一座高为127.5 m的高土石坝为例,通过室内试验和三轴试验测得坝体材料的物理性质指标和邓肯张E-B模型参数,采用有限元计算方法,计算竣工期和渗流稳定期复合土工膜高土石坝坝体应力、应变和变形以及大坝渗流量,并和粘土心墙防渗计算结构进行对比,并对复合土工膜心墙是否发生水力劈裂进行判断。结果表明:由于堆石体材料的流变性,引起了坝体的竖向位移和水平位移。复合土工膜心墙与粘土心墙相比,复合土工膜对降低坝体浸润线、减小坝体孔隙水压力均有显著作用,减小幅度在50%左右,且复合土工膜不会发生水力劈裂等不利问题。

Study on impermeability clay core wall and composite geo-membrane for high earth-rock dam

Stress and deformation properties and hydraulic fracture under the state of static force are the key problem of design and construction for high earth-rock dam. Taking a 127.5m high earth-rock dam for example, the paper got the index of physical properties and Duncan-Chang E-B model parameters of dam material through the laboratory experiments and triaxial tests, and computed the stress and deformation and seepage quantity of high rock-fill dam with composite geo-membrane during the period of completion and seepage stabilization by use of finite element method. It also judged whether the hydraulic fracturing of the core wall took place. The calculation results show that because of the rheology of rockfill material, vertical and horizontal displacements of dam are taken place. The composite geo-membrane has an evident effect on reducing embankment seepage, decrease pore water pressures and saturation line of embankment dam, and prevent the hydraulic fracturing produced in dam body compared with clay core wall.