盾构隧道地震响应试验研究

Experimental study on seismic response of shield tunnel

当遭遇强震、地质条件或结构刚度突变时,盾构隧道结构可能发生严重震害,且震害主要集中在接头处。采用振动台试验、接头局部足尺试验,针对盾构隧道穿越软硬交界地层、联络横通道、纵向接头等抗震薄弱部位开展系列研究。研究发现:地震作用下软硬交界地层中盾构隧道仍具有对地层位移的追随性,但表现出与均质地层不同的"双峰值"现象,较大结构内力响应分布于地层交界面两侧2.5倍隧道直径范围;盾构隧道与联络横通道的连接刚度对隧道力学响应有显著影响,刚性连接对主隧道的影响范围约为3倍横通道宽度,柔性连接时减小至1.5~2倍横通道宽度;地震作用下盾构隧道纵向接头主要承受轴向拉力或压力,螺孔侧管片以主压应变为主,套筒侧以主拉应变为主,破坏试验表明套筒与管片组成破坏链,分别表现为滑移破坏、拉裂破坏。研究结论可为盾构隧道抗减震设计提供参考。

When encountering strong earthquake,geological conditions or structural stiffness mutation,serious earthquake damage may occur to shield tunnel,and the earthquake damage mainly concentrates on the joints.Through shaking table test and indoor static test,a series of studies were carried out for the weak seismic parts or conditions such as the shield tunnel passing through the soft and hard interface stratum,the joint of cross passage and the longitudinal.The results showed that the seismic response of the shield tunnel in the hard-soft interface stratum still had followability,but showed a"double peak"phenomenon,and the larger internal force response values were distributed in the range of 2.5 times the tunnel diameter on both sides of the stratigraphic interface.The connection stiffness of shield tunnel and transverse passage had an effect on mechanical response of tunnel,and the influence range of rigid connection on the main tunnel was about 3 times of the width of a cross passage,and it was reduced to 1.5~2 times in the case of flexible connection.The longitudinal joints of shield tunnel mainly bear axial tension or pressure under the seismic.The segments on the bolt hole side and sleeve side were dominated by compressive strain and tensile strain,respectively.The failure test showed that the sleeve and the segment constitute a destructive chain.The sleeve and the segment exhibit slip failure and tension crack failure,respectively.The research can provide a reference for seismic design of shield tunnel.