多空洞缺陷对隧道地震响应影响分析

Analysis of influence of multi-cavity defects on seismic response of tunnel

为研究衬砌背后空洞对结构地震响应的影响,从空洞位置、数量、尺寸效应及裂损等方面对某实例工程进行多工况分析。基于波动理论和扩展有限元法,运用ABAQUS建立损伤模型,结合MATLAB生成动力黏弹性边界及地震波等效节点力荷载进行求解,实现静-动分析。结果表明:1)结构各部位主应力对空洞缺陷的敏感性为拱墙处最显著,其次为拱肩,而拱顶相对较小。2)衬砌双侧存在空洞缺陷时,其应力分布比单个空洞情况更为复杂,尤其是双侧拱墙背后存在空洞相比单侧情况,最大拉、压应力值提高了2~3倍。3)拱顶内侧压应力、外侧拉应力随其背后空洞径向深度和环向角度的增大而增大,特别是拱脚内侧承受较大拉应力。4)无空洞时,隧道基本以压应力为主,不易发生裂损;当存在空洞缺陷时,其会放大地震效应,使得结构在0.3g强震作用下,拱脚部位附近的拉应力显著增大,进而发生开裂现象。

In order to study the effect of cavity behind lining on seismic response of structure,multi-working condition analysis was carried out for an example project from the aspects of cavity location,number,size effect and crack damage.Based on the wave theory and extended finite element method,the damage model was established by ABAQUS,and the dynamic viscoelastic boundary and equivalent node force load of seismic wave were generated by MATLAB to solve the static and dynamic analysis.The results show that:1)The sensitivity of principal stress to cavity defect is most obvious in the arch wall,followed by the arch shoulder,and relatively small in the vault.2) The stress distribution is more complex when there are cavities on both sides of the lining than when there are single cavities,especially when there are cavities on both sides of the arch wall,and the maximum tensile stress and compressive stress are 2 to 3 times higher than that when there are cavities on one side.3) The compressive stress inside the vault and the tensile stress outside the vault increase with the increase of the radial depth and circumferential angle of the vault,especially the tensile stress inside the arch foot.4) When there is no cavity,the tunnel is basically dominated by compressive stress,which is not easy to crack;When there is a cavity defect,it will amplify the seismic effect,making the tensile stress near the arch foot significantly increase under the strong earthquake of 0.3g,and then the cracking occurs.