盾构隧道施工扰动对隧道与车站地震响应的影响分析

Analysis of the influence of shield tunnel construction disturbance on the seismic response of tunnel and station

摘要:

盾构隧道施工扰动会改变隧道周围土体的应力状态和力学性质，从而影响隧道与车站后期的地震响应。通过数值模拟分析了不同程度的应力状态改变和剪切模量衰减对地震时隧道周围土体、管片结构以及车站结构地震响应的影响。结果表明：（1）应力状态改变程度越大（地层应力释放率越大），隧道周围土体的初始剪应力越大，隧道底部土体的剪应变越大，超静孔隙水压力越大；应力状态改变程度越大，地震引起的管片弯矩和轴力越大（应力释放率30%时地震引起的左拱肩峰值管片弯矩和轴力增量分别是应力释放率10%时的165%和527%），车站侧墙和柱的相对水平位移越大。（2）剪切模量衰减程度越大，隧道周围土体的剪切模量越小，隧道周围土体越软，隧道底部土体的剪应变越大，超静孔隙水压力越大；剪切模量衰减程度越大，地震引起的管片弯矩和轴力越小（模量衰减大时地震引起的左拱肩峰值管片弯矩和轴力增量分别是模量无衰减时的67%和40%），车站侧墙和柱的相对水平位移越小。因此，盾构隧道的施工扰动程度对后期隧道与车站的地震响应有明显影响，在隧道与车站的抗震设计时应考虑盾构隧道前期施工对周围土体应力状态及力学性质改变的影响。

Abstract:

The construction disturbance of shield tunnel will change the stress states and mechanical properties of soils around the tunnel, and then affect the subsequent seismic response of tunnel and station. The effects of different degrees of stress state change and shear modulus attenuation on the seismic responses of soils around the tunnel, segment structure and station structure during earthquake were analyzed by numerical simulation. The results show that: (1) The greater the degree of stress state change (the greater the stress release rate) was, the greater the initial shear stress of the soils around the tunnel, the larger the shear strain at the bottom of tunnel, the larger the excess pore water pressure; The greater the degree of stress state change was, the greater the bending moment and axial force of segment caused by the earthquake (the increments of peak bending moment and axial force of segment at left arch shoulder caused by the earthquake with the stress release rate of 30% were 165% and 527%, respectively, of those with the stress release rate of 10%), the greater the relative horizontal displacements of side wall and column of station. (2) The larger the shear modulus attenuation was, the smaller the shear modulus of the soils around the tunnel, the softer the soils around the tunnel, the larger the shear strain at the bottom of tunnel, the larger the excess pore water pressure; The larger the shear modulus attenuation was, the smaller the bending moment and axial force of segment caused by the earthquake (the increments of peak bending moment and axial force of segment at left arch shoulder caused by earthquake with large degree of modulus attenuation were 67% and 40%, respectively, of those without modulus attenuation), the smaller the relative horizontal displacements of the side wall and column of station. Therefore, the degree of construction disturbance of shield tunnel has obvious influence on the subsequent seismic responses of tunnel and station, so the influences of early construction of shield tunnel on the changes of stress states and mechanical properties of surrounding soils should be considered in the seismic designs of tunnel and station.