椭圆空洞对盾构隧道地震易损性曲线影响研究

Seismic vulnerability curves of shield tunnels influenced by adjacent elliptical cavity

摘要:

采用增量动力分析方法,探究水平向地震下地层空洞对盾构隧道地震响应特征的影响规律。针对管片损伤及周边地层应力,选择弯矩比作为性能评价指标,峰值加速度(PGA)及峰值速度(PGV)作为衡量地震强度指标(IM),阐明椭圆形空洞对管片抗震性能的影响,得到隧道结构的地震易损性曲线。研究表明:椭圆空洞加大了浅埋盾构隧道的地震破坏概率;PGA与PGV均可作为IM并获得相应的隧道易损性曲线;使用弯矩比作为破坏指标,PGV作为地震动指标,其对应的易损性曲线对地层变异性更敏感。研究结论可为潜在空洞发育区防震方案的制定提供参考。

Abstract:

The effects of adjacent cavities on the seismic response characteristics of shield tunnels under horizontal seismic excitation were explored with the incremental dynamic analysis method. Given the segment damage and stress distribution encircling the tunnel, the bending moment ratio was selected as the performance evaluation index, and the peak ground acceleration (PGA) and peak ground velocity (PGV) were used as seismic intensity measures (IMs). Then, the influence of the elliptical cavity on the seismic performance of the segment was expounded, and the seismic vulnerability curves of the tunnel structure were obtained. Results show that the seismic damage probability of the shallowly buried shield tunnel increases because of the effect of the adjacent elliptical cavity. The PGA and PGV can be used as IMs for the development of the corresponding vulnerability curves of tunnels. When the bending moment ratio as damage index and PGV as intensity measure are used, the vulnerability curves are more sensitive to variation in strata than those of PGA. The research conclusion can provide a reference for the formulation of earthquake prevention schemes in regions with potential cavities.