基坑垮塌的离散元模拟及冗余度分析

目前基于构件设计的基坑设计理论使得很多支护体系缺乏必要的冗余度，并导致了众多基坑事故。将离散元方法引入到基坑垮塌模拟和冗余度研究中，提出了基于局部破坏的冗余度分析模拟方法。进而以探究支撑端部连接对支护结构冗余度的影响为例，对两种连接情况的基坑的破坏过程进行了模拟，对其中的连续破坏现象进行了分析，并将模拟结果与实际工程进行了对比。结果表明，支护体系冗余度的提高可以有效地抵抗连续破坏的发生，防止基坑在局部损伤情况下，由一种形式的破坏引发其他形式的破坏，由局部破坏导致整体崩溃。另外，模拟结果也验证了离散元法在基坑破坏模拟中的适用性与可行性，为类似地下工程的破坏模拟和基坑冗余度的深入研究提供了参考。

Discrete element simulation and redundancy analysis of excavation collapse

The conventional design method of deep excavation retaining structure generally processes element by element, consequently, some retaining structures are probably lack of essential redundancy, which is one of the reasons that led to many catastrophic collapses of deep excavations. Discrete element method (DEM) is adopted for simulation of excavation collapse and study of retaining structure redundancy; and a simulation method based on local failure for analyzing redundancy is also proposed. Here the influence of prop connection on the retaining structure redundancy is selected as an example of redundancy research. The failure processes of two excavations with different types of prop connections are simulated; and the phenomena of progressive collapses in them are compared and analyzed. Furthermore, the simulation results are also validated by comparison with the realistic case of excavation collapse. It is indicated that the improvement of the retaining structure redundancy can effectively resist the progressive collapse in deep excavation, and then the transformation of a type of damage to other types of damages and the evolution of the local damage to entire collapse can be avoided. In addition, the simulation results also show that the excavation collapse using DEM is feasible and reasonable, so as to provide a reference for simulation of such collapse problems in underground engineering and further study of redundancy in deep excavations.