基于岩体动力损伤的地下工程施工过程数值分析

Numerical Analysis Method of Construction Process for Underground Engineering Based on Dynamic Damage Effect of Rock Mass

在大型地下工程爆破、开挖及支护施工过程中,采用数值分析方法预估围岩开裂深度及爆破损伤程度对工程设计和施工可以起到事先指导的作用。采用考虑累积应变和荷载作用时间的Yang-Liu率相关动力损伤模型,定义与裂纹扩展密度相关的损伤系数,将损伤特性反映在荷载增量迭代计算中,形成弹塑性损伤本构模型。论述了爆破荷载和开挖荷载的计算、施加及迭代方法,可以合理反映爆破对围岩稳定的影响以及初始地应力释放、锚固支护施加的时机和效果。通过工程实例的计算,得出了某水电站地下洞室在爆破荷载、开挖荷载和锚固支护作用下应力场、变形、破坏区及损伤系数的分布规律,分析结果可以为工程设计提供依据。

In the excavation of underground project,the numerical simulation method is used to predict cracking depth and damaged range of surrounding rocks by blasting excavation,which can play a guiding role in advance in engineering design; in which,a scientific and reasonable damage model and iterative calculation method are the most important key technique. The Yang-Liu damage model considering cumulative strain and load time is used to define the co-efficient of damage associated with crack propagation density. The rock damage characteristic is reflected in the iteration calculation process of an incremental load,thus an elasto-plastic damage constitutive model is formed. The procedure of FEM discusses the calculation of blasting loads and excavation load,applied means and iterative calculation methods that can reflect reasonably the influence of blasting,the release of initial geostress,imposed timing and effects of reinforcement measure. The calculation of an underground hydropower station carries out the distribution laws of the second stress field,displacement,failure zones and damage co-efficient in the condition of blasting,excavation load and anchoring supporting systems which can provide a certain basis for engineering design.