标题： 临界状态土模型的隐式子步进格式 显示英文标题

标题： Implicit Sub-stepping Scheme for Critical State Soil Models

摘要： 临界土模型的应力积分通常基于隐式欧拉算法，其中通过采用返回映射算法来校正应力预测值。在大荷载步的情况下，求解计算塑性乘子的局部非线性系统可能无法得到解。为了解决这个问题，应使用子步进方案来提高局部非线性系统解法策略的收敛性。然而，子步进方案的切线算子的复杂性较高。这使得使用牛顿-拉夫森算法获得全局二次收敛变得复杂。本文为改进的Cam-Clay模型和统一粘土与砂模型的隐式子步进积分开发了一种一致切线算子的公式。该公式高效且可用于涉及大荷载步的问题，如隧道模拟。 显示英文摘要

摘要： The stress integration of critical soil model is usually based on implicit Euler algorithm, where the stress predictor is corrected by employing a return mapping algorithm. In the case of large load step, the solution of local nonlinear system to compute the plastic multiplier may not be attained. To overcome this problem, a sub-stepping scheme shall be used to improve the convergence of the local nonlin- ear system solution strategy. Nevertheless, the complexity of the tangent operator of the sub-stepping scheme is high. This complicates the use of Newton-Raphson algorithm to obtain global quadratic convergence. In this paper, a formulation for consistent tangent operator is developed for implicit sub-stepping integration for the modified Cam-Clay model and unified Clay and Sand model. This formulation is highly efficient and can be used with problem involving large load step, such as tun- nel simulation.