水平入射条件下地下岩体浅埋平行洞室群地震动力响应分析

Analysis of Seismic Dynamic Response for Underground Shallow Buried Parallel Cavern Group under Condition of Horizontal Incidence

结合湛江某地下水封洞库工程,建立了大型地下岩体浅埋平行洞室群的有限元—无限元耦合动力计算模型,以地震位移波为激励方式,进行了水平入射条件下的洞室群时域地震响应分析。从应力、位移和应变能三个方面的分析结果表明,在水平地震作用下,平行对称布置的洞室群围岩岩体受地震水平剪切运动控制,各个洞室围岩的应力、位移和应变能的响应幅值均以开挖后稳定的初始基本量为对称轴而变化;应力响应幅值变化量对围岩材料强度不起主要作用;各洞室不同测点处的总位移响应时程形态基本一致,其中边缘洞室的边墙相对位移最大响应幅值约为中间洞室最小值的0.7倍;围岩应变能的积聚主要集中在边缘洞室的拱顶和底板。三个方面的分析同时表明了平行布置的洞室群受地震影响的程度以最外侧洞室为最大,并依次向中间洞室递减,边洞室为地震作用最薄弱位置。

Based on the background of Zhanjiang underground water-sealed storage in rock caverns, the Finite-Infinite element coupling dynamic model was established for underground rock shallow buried parallel cavern groups. Taking seismic displacement wave as an incentive type, the time field seismic response analysis of cavern groups was carried out. The analysis results indicated that from three aspects of stress, displacement and strain energy, surrounding rock of cavern groups arranged in parallel symmetric is controlled by seismic horizontal shear action, the response amplitude of stress, displacement and strain energy of every cavern are symmetrically changed with their stable initial basic variables after excavation; the strength of surrounding rock material will be not affected by the change of stress response amplitude; the displacement response forms of every cavern at different monitoring point are almost similar, and the maximum response amplitude of relative displacement of sidewall in marginal cavern is around 0.7 times the minimum amplitude of that in middle cavern; the strain energy in surrounding rock is mainly accumulated in the top arch and bottom of marginal cavern. The analysis obtained from three aspects also showed at the same times that the maximum extent influenced by seismic action is for marginal cavern, the extent influenced will be reduced toward the direction of middle cavern, which is the weakest at the side cavern.