逆断层错动对隧道结构影响研究

Research on Influence of Reverse Fault Dislocation on Tunnel Structure

敦(敦煌)格(格尔木)铁路阔克萨隧道穿越活断层,对隧道工程设计挑战性较大。为保证活动断层段隧道结构稳定、运营安全和震后可修复,以穿断层阔克萨隧道为研究对象,考虑断层两侧围岩差异较大的特殊性,借助FLAC3D有限差分软件与室内模型试验,采用数值模拟与试验相结合的方法,对逆断层错动下隧道结构受力变形情况与抗错动设计效果进行研究。结果表明:二者揭示的规律基本一致,验证了本次研究的可靠性;隧道结构设减震缝比未设减震缝的抗错动能力得到较大提高,以结构应变为例,最大纵向应变受断层错动影响程度降幅达43.14%,最大环向应变降幅37.97%;断层错动对围岩较弱的下盘影响更大,在逆断层中,围岩强弱比隧道是否在上升盘的影响性更大;隧道与断层相交处结构边墙破坏最为严重,为最不利处,拱顶次之,仰拱最小。

Kuokesa Tunnel of Dunhuang-Golmud Railway passes through active fault, which is a great challenge to tunnel engineering design. In order to ensure the structural stability, operation safety and post earthquake repairability of the tunnel in the active fault section, the Kuokesa Tunnel is taken as the research object. Considering the particularity of the great difference between the surrounding rocks on both sides of the fault, the stress and deformation of tunnel structure under reverse fault dislocation and the effect of anti dislocation design are studied by means of FLAC3 D finite difference software and indoor model test. The results show that: the laws revealed by the two methods are basically the same, which verifies the reliability of this study;the anti dislocation ability of tunnel structure with damping joint is greatly improved than that without damping joint;in view of the structural strain, the maximum longitudinal strain is decreased by 43.14% due to fault dislocation, and the maximum circumferential strain is 37.97%;the fault dislocation has greater impact on the weak footwall of surrounding rock;in the reverse fault, the strength of surrounding rock has even greater impact whether the tunnel is in uplift wall;the damage of side wall at the intersection of tunnel and fault is the most serious, which is the most disadvantageous place, followed by the vault and the invert the least.