土石坝极限抗震能力的上限有限元法

基于极限分析上限定理,考虑堆石料内摩擦角较大以及抗剪强度具有非线性的特性,提出一个用于求解土石坝极限抗震能力的有限元计算方法。该方法通过功能平衡条件、位移协调条件、边界条件、屈服条件以及所求极限荷载,形成标准的二阶锥规划数学模型,并用内点法进行优化迭代求解,得到土石坝坡极限抗震能力的上限值。运用该方法对一个典型面板堆石坝进行抗震极限分析。结果表明:按规范设计的土石坝具有较强的抗震能力,且竖向地震力对大坝的极限抗震能力存在一定影响;此外上限有限元法具有较高的计算精度及工程实用价值。

Upper Bound FEM to Analyze the Ultimate Aseismic Capability of Earth-rock Dams

An upper bound limit analysis finite element method is developed to study the ultimate aseismic capacity of earth-rock dams. Considering the large value of the internal friction angle and the non-linear shear strength parameters of earth-rock materials, a static form, which is the corresponding dual problem of the second-order cone programming for upper bound limit analysis, is formulated with constraints based on the yield criterion, flow rule, boundary conditions, and the energy-work balance equation. The upper bound solution of ultimate aseismic capacity is then iteratively obtained by a state-of-the-art interior-point algorithm. The proposed method is applied to the seismic stability problem of a typical earth-rock dam. The results indicate that the earth-rock dams designed according to code have strong seismic capabilities, as the influence of vertical earthquake load is considered. These results also demonstrate the high calculation accuracy and practical value of the proposed method.