基于离散-连续耦合方法的地下结构在地震中破坏过程模拟

基于改进后的土体离散-连续耦合算法，对坂神地震中产生塌陷的神户大开地铁车站的破坏过程进行了数值模拟。通过改进适用于Lagrange乘子法求解的优化模型，来强化离散和连续模型在耦合边界上力的相容性，将改进后的算法嵌入离散-连续耦合动力模型。在耦合边界通过交换速度和力保证耦合模型的连续性，通过自振柱模拟和循环双轴模拟使离散区域土体的宏观动力属性与连续土体模型一致。土体离散-连续耦合方法可以从细观尺度描述重点考察区域土体和结构的破坏过程，并有效降低离散元的模拟规模。模拟得到的车站破坏形式与文献中现场情况非常接近，并且从定量角度与已有文献中基于连续体的模拟结果进行比较。

COLLAPSE SIMULATION OF THE SUBWAY STRUCTURE DURING THE EARTHQUAKE BASED ON THE TWO-SCALE COUPLED METHOD

Based on the improved discrete-continuum soil model, simulation of the collapse process of the Daikai station and the large deformation of the surrounding soil is performed. This paper improves the optimization model which is solved by the Lagrange multiplier method and is utilized to enforce force continuity on the coupling boundary. Then this improved model is applied to the discrete-continuum model. The continuity between the discrete and continuum domains is fulfilled by interchanging velocities and forces between them. By performing the free vibration column simulation and numerical cyclic biaxial tests, the degradation curve for the particle assembly is fully obtained and applied to the continuum model. Damage pattern obtained from the simulation is very similar to the collapsed situation of the subway station after the earthquake. Besides, from a quantitative perspective, the subway station column’s horizontal differential displacement obtained from simulation is compared with that from existed paper. It is shown that, coupled macro-micro approach can efficiently reduce particle numbers and provide a micro perspective on soil and the structure experiencing damages in the concerned zone.