土石坝掺砾心墙料的压缩特性研究北大核心CSCD

土石坝施工完成后的坝体沉降变形是工程上重要的关注点。本文选用一种风积土料和一种花岗岩砾石料,对掺砾土料的压缩特性开展试验研究,探讨掺砾比例、应力等级以及压实度对掺砾土料压缩特性的影响规律。试验结果表明:心墙土料掺砾后压缩性有着明显的改善,土料压缩模量随竖向应力的增大而提高,但随着竖向应力的持续增大,压缩模量的增加速度逐渐减小;掺砾比例和压实度均对土料压缩模量有较为明显的影响,随着掺砾比例和压实度的增加,压缩模量基本呈现随之提高的变化规律,但也发现过高的掺砾比例将会因砾石受到竖向应力产生颗粒破碎而使压缩模量降低;掺砾土料的孔隙比随竖向应力的增大而减小,低应力条件下孔隙比减小的速率较快,高应力条件下孔隙比减小速率下降并趋于稳定;结合掺砾后压缩模量的变化规律,对坝体不同高度处心墙掺砾比例的优化调整进行了探讨。

Compression characteristics of anti-seepage material mixed with gravel for core wall of earth-rock dam

Settlement and deformation of the earth-rock dam body after completion is an important concern in engineering practice. In this work, an experiment was conducted on the compression characteristics of a gravel-mixed soil material－an aeolian sandy soil material mixed with a granite gravel material, focusing on the influence of gravel proportion, stress level, and compactness. The test results show that the compressibility of this mixture is significantly higher than that of the soil; its compression modulus increases with the increasing vertical stress, but with a further vertical stress increase, the increase rate of the modulus decreases gradually. Both gravel proportion and compactness have an evident effect on the modulus. With an increase in gravel proportion or compactness, compression modulus shows a basically increasing trend. However, we also find excessive gravel proportion will reduce compression modulus due to particle breakage caused by the vertical stress of gravel. The void ratio of gravel-mixed soil decreases with vertical stress; it decreases rapidly under low stress while it tends to be stable under high stress. Finally, combining with the variation trends in compression modulus, we investigate the optimal adjustment of gravel proportion in the core wall at different heights of the dam body.