碾压混凝土层间拉伸破坏过程的数值模拟研究

碾压混凝土软弱层的破坏是高碾压混凝土坝稳定性的一个重要问题。应用材料破坏全过程分析的软件系统MFPA2D，充分考虑了碾压混凝土的非均质性的细观结构特征，模拟再现了三种层面处理方式的软弱层的拉伸破坏过程，确定了裂缝的起裂荷载，计算得到了三种碾压混凝土紧凑拉伸试件裂缝的起裂断裂韧度和失稳断裂韧度。研究表明，在所讨论的三种软弱层的处理方式中，最为有效的是下层混凝土终凝后对层面进行凿毛（冲毛）处理；其次是下层混凝土初凝后终凝前，对层面进行铺水泥粉煤灰砂浆的处理；最不好的是下层混凝土初凝后终凝前，在层面上直接铺筑上层混凝土，在施工中要避免这种情况的发生。据此提出了在施工中要尽量避免或减少对下层混凝土层面的过多扰动的建议。

Numerical simulation of tensile failure at adjacent concrete layers in RCC dams

The software MEPA was applied to simulate the tensile failure process of incompetent surface between adjacent layers of RCC dams. The heterogeneous structure of concrete at microscopic level was considered. The failure processes of the surface with different treatments of the lower layer surface were simulated and the bearing capacities at the instant of cracking were determined. The toughness for initial caracking and toughness for failure corresponding to different ways of surface treatment were calculated. The result shows that roughening the poured concrete surface by pitting at the moment of final setting of concrete is the moset effective way to promote the failure resistance.