中文摘要：

混凝土坝接近破坏时混凝土材料进入塑性状态发生有限变形，研究几何非线性和包含应变软化的材料非线性对其极限承载能力的影响具有实际意义。该文的研究中本构律考虑材料非线性的应变软化，协调律考虑几何非线性，平衡律涉及几何非线性，采用超载法分析混凝土坝的极限承载能力，选取弧长法计算混凝土坝上游水压荷载位移曲线极值点以及下降段，给出双重非线性即包含应变软化的材料非线性和几何非线性对重力坝系统整体极限承载能力的影响。

英文摘要：

The finite deformation and plasticity will occur when a concrete dam is close to failure. It is veryimportant to study the effect of geometric nonlinearity and material nonlinearity including strain softening on maximum bearing capacity. In this paper, material constitutive relation with strain softening, nonlinear geometry equations and equilibrium differential equations considering geometric nonlinearity are presented. The maximum bearing capacity of a concrete dam is obtained by the over-loading method and Arc-length method used to calculate the peak point and falling branch of the load-displacement curve, then the effect of double nonlinearity, including geometric and material nonlinearity considering strain softening, on the maximum bearing capacity are discussed.