近接桩基盾构隧道施工管片力学行为研究

Research on the Mechanical Behavior of a Segment of a Shield Tunnel Adjacent to a Pile Foundation

盾构隧道衬砌管片在施工阶段处于复杂的受力状态,易出现局部破损现象。文章以深圳地铁5号线近接桩基时盾构隧道施工为研究背景,通过现场测试对衬砌所承受的轴力和弯矩进行了分析,以此来探究盾构隧道管片的力学特性。研究结果表明:上覆建筑物的全风化花岗岩层中,管片脱出盾尾后桩基荷载将传递给隧道上部土体,最后传递至衬砌管片,管片环受到较大的附加应力作用;管片刚拼装上时试验环内力较小;当管片脱出盾尾时其内力达到最大值;稳定后的管片内力一般相较刚脱出盾尾时稍小。由于岩层破碎且极度发育,透水性好,孔隙水压力变化速度较快,且能较快趋于稳定。

During shield construction it is common for local damage of the segment lining to occur due to complex forces being applied. Based on the shield tunneling of the Shenzhen Subway line 5 in clay ground, this paper analyzes the axial force and moment of the shield tunnel segment lining in order to study the mechanical behavior of the shieht tunnel segment. The results show that： in the overlying fully-weathered granite buildings, the load on the pile founda- tion was passed to the upper soil and finally to the lining segment when the segment emerged from the shield tail, and the segment ring was subjected to larger additional stress; the internal force was relatively small when the segment was assembled, the internal force of the segment reached its maximum peak when the segment emerged from the shield tail; and the stable internal force of the segment is a little lower than that which occurs when the segment emerged from the shield tail. Because of the fractured and developed rock mass, permeability was good and the pore water pressure changed rapidly, achieving stability quickly