衬砌背后空洞对隧道抗震性能影响分析

目前关于隧道震害问题的研究主要集中于隧道洞门和洞口段,实际上仍有不少洞身衬砌在地震中产生严重震害,其中一个重要原因便是衬砌背后存在空洞或者回填不密实。通过大型有限元软件ABAQUS,采用无限元边界解决地震波的反射震荡问题,研究衬砌背后空洞对隧道的地震动力响应的影响。通过分析得到:密实状态下,即使在较大地震动力作用下,衬砌结构仍处于良好的受压状态;一旦衬砌背后存在空洞,地震作用下脱空区衬砌产生很大拉应力,可能导致衬砌开裂坍塌;同时,空洞处周边围岩产生塑性区,易引起岩体松弛掉落冲击衬砌。

Effect of Void behind Lining on Seismic Performance of Tunnel

At present, analyses of seismic damage to tunnels have focused on the tunnel portal and portal section.However, there are still many deeply-buried tunnels that have been badly damaged by earthquakes;an important reason for this is the existence of voids behind the lining or because the lining backfill is not dense.However, studies on the relationship between voids behind the lining and the dynamic characteristics of earthquakes are few.In this study, the seismic performance of a tunnel with voids behind the lining are studied using the finite element software ABAQUS.The analysis reveals the following:if the lining is tightly and firmly stuck to the surrounding rocks, even under larger seismic action, the lining remains in a good state of compression.Once voids are present behind the lining, the lining that does not have the support of the surrounding rock comes under great tensile stress, resulting in cracking of the lining, which causes tunnel collapse.In addition, during earthquakes, larger plastic deformation appears in the surrounding rock without lining support than in those with lining support, causing the rock to more easily relax and fall off.