基于黏弹性边界的地下洞室地震响应分析

Analysis of Seismic Response of Underground Cavern Based on Viscoelastic Boundary

以某抽水蓄能电站地下洞室群为研究对象,基于有限元分析软件ABAQUS采用自编程序实现三维黏弹性人工边界的创建,并通过算例验证了方法的可行性。采用时程分析法将黏弹性人工边界应用于地下洞室群地震动力响应分析中,并以震前洞室作为比较,研究了三向地震动作用下洞周围岩的应力、位移和塑性区的分布特点及支护结构的受力特征。结果表明,洞周围岩的主拉应力和主压应力幅值减小,但受拉区面积有所扩大,塑性区变化不明显;处于洞周边墙位置的锚杆和锚索受力减小,顶拱位置的锚杆和锚索受力增加,其中短锚杆变幅较大;在地震动荷载的往复作用下,洞周围岩的变形主要朝向临空面,监测点的位移时程与输入位移时程曲线波形一致,在幅值上有一定的放大。

Taking the underground cavern group of a pumped-storage power station as the research object, based on the finite element analysis software ABAQUS, a self-compiled program was used to realize the creation of three-dimensional viscoelastic artificial boundary. The feasibility of the method was verified by a calculation example. The viscoelastic artificial boundary was applied to the seismic dynamic response analysis of underground cavern groups by time-history analysis method. Using the cavern before earthquake as a comparison, the stress, displacement and plastic area distribution characteristics of the rock around the lower cavern for three-way seismic action and the mechanical characteristics of the support structure were studied. The results show that under the reciprocating action of the ground motion load, the deformation of the rock around the cavern is mainly toward the empty surface, and the displacement time history of the monitoring point is consistent with the input displacement time history curve waveform, and there is a certain amplification in the amplitude of the rock around the cavern. The amplitude of the main tensile stress and the main compressive stress is reduced, but the area of the tensile zone has been enlarged, and the plastic zone has not changed significantly;The force of anchor rod and anchor cable at the position of the surrounding wall of the hole are reduced, and the force of anchor rod at the top arch position and the anchor cable are increased, and the short anchor rod has a larger amplitude.