混凝土–堆石混合坝土压力模型试验研究

混凝土–堆石混合坝是一种新型坝体结构。混凝土墙后土压力的大小和分布会直接影响混凝土墙甚至整个坝体的稳定性,而目前针对其研究较少。基于此,开展混凝土–堆石混合坝模型试验,研究填筑和蓄水期混凝土墙的变位模式和墙后土压力分布,同时根据加卸荷三轴试验结果建立非极限状态下堆石内摩擦角发挥值、墙土摩擦角发挥值随位移的变化关系,提出初始位移的概念,在此基础上推导出考虑墙体水平位移的准极限状态土压力计算公式。研究表明:混凝土墙的变位模式以平动为主,墙后土压力随混墙体水平位移变化较大,蓄水结束时刻墙后土压力为填筑结束时刻墙后土压力的2倍左右;所提公式能够较好地反映土压力随墙体水平位移的变化规律,可作为库仑土压力的补充。

Model experiment investigation of earth pressure of the concrete-rockfill combination dam

Concrete-rockfill combination dam(CRC dam) is a new type of dams. The stability of the concrete wall and the whole dam was influenced by the value and distribution of earth pressure. A model test was carried out to measure the distribution of earth pressure along the height of the wall and to investigate the displacement mode in rock filling and water impoundment periods. According to the results of loading and unloading triaxial test，the non-linear relationships between the wall displacement and the mobilized internal friction angle，the friction angle between the concrete wall and the rockfill were established under the quasi-limit state. The concept of initial displacement was proposed，and a calculation method of quasi-limit state earth pressure considering the displacement was deduced. The result shows that the displacement of the concrete wall was mainly the mode of translation. Earth pressure varied with the displacement of the concrete wall obviously，and the earth pressure at the end of impoundment period was approximate twice than that in the filling period. The proposed formula reflected well the change of earth pressure with wall displacement and is an effective supplement to Coulomb?s theoretical formula.