基于接触摩擦单元的面板坝子模型分析

考虑高面板堆石坝实际的施工特点和面板分期浇筑特点,提出采用子模型法分析面板的应力变形,而面板与挤压边墙之间的特殊边界采用基于莫尔–库仑准则的无厚度接触摩擦单元进行模拟。子模型法把面板、挤压边墙以及面板周边的混凝土趾板从面板堆石坝的整体模型中脱离出来作为研究对象,在挤压边墙的底部施加与其相连的已知垫层料位移,在面板的表面施加水压力,进行数值分析。应用子模型分析面板的应力变形最大的优点就是可以充分考虑面板浇筑前的削坡和补坡等施工程序,以真实反映面板浇筑前的初始变形条件。由于子模型的单元网格规模相对较小,因而混凝土面板可以采用精细的单元网格以真实模拟面板沿厚度方向的应力梯度分布,面板也可以采用复杂的非线性本构模型和开裂破坏准则以及考虑施工期瞬态温度荷载对面板应力的影响。同时,对面板的竖缝和周边缝也可进行详细模拟。工程数值算例结果表明基于接触摩擦单元的子模型法计算面板应力变形的可行性和实用性。

STUDY ON SUBMODELING METHOD OF CONCRETE-FACED ROCKFILL DAM BASED ON CONTACT FRICTION ELEMENT

Submodeling method is presented to compute the stress and deformation of concrete face slab by considering the construction characteristics of concrete-faced rockfill dam and concrete face slab constructed with different stages.A contact friction element without thickness based on Mohr-Coulomb friction model is used to simulate the special boundary between the concrete crushing-type side wall and the concrete face slab.The concrete face slabc,oncrete crushing-type side wall and toe board are looked as submodel,which is separated from the whole model of CFRD.The calculated displacement in the whole model is applied to the bottom side of the crushing-type side wall,and the water pressure is applied to the surface of the concrete face slab.The advantage of submodeling method is that the construction procedure of cutting and filling of slope can be considered accurately in analysis,which is an essential condition to the simulation of the stress and deformation of concrete face slab.The size of submodel is relatively small,so the concrete face slab can adopt dense mesh to simulate steep stress distribution along thickness,and complex nonlinear constitutive relationship and cracking rule are also employed to simulate stress and deformation of concrete face slab under the transient temperature loading.In addition,the vertical joint and peripheral joint of the concrete face slab are also simulated.The analytical results show that the submodeling method based on contact friction element to compute the stress and deformation of the concrete face slab is feasible.