局部破碎带渗水条件下海底隧道稳定性的有限元极限分析

 以存在局部破碎带的青黄海底公路岩质隧道为例，考虑到海水的渗透性，采用有限元极限分析法分析海底隧道岩体注浆加固前、后的稳定性。计算结果表明，隧道整体是安全的，此种情况下，隧道衬砌原则上可按无水压设计，衬砌厚度与采用全水头设计相比可以大大降低。但当存在局部破碎带时，隧道安全系数降低，破碎带越宽，注浆堵水圈厚度越小，安全系数越小。与完整围岩破裂面位于两侧相比，含倾角45°破碎带围岩的稳定性最差。因此，必须做好破碎带的超前注浆堵水加固，以减少其渗水量，并对破碎带进行局部加固，此种情况下，隧道衬砌原则上可按有水压设计。

LIMIT ANALYSIS OF SUBSEA TUNNEL STABILITY BY FINITE ELEMENT METHOD IN FAULT-RUPTURE ZONE WITH WATER PENETRATION

Considering the sea water seepage，limit analysis by finite element method is used to study the stability of a subsea tunnel in which the fracture zone exists. Result shows that the tunnel is safe for the intact surrounding rock. Under the condition，the lining of the subsea tunnel can be designed without water pressure；and the lining thickness can be reduced remarkably. The calculation results show that the fault-rupture zone decreases the stability of tunnel obviously. The wider the fracture zone is，the smaller the safety factor is. The thicker the rock grouting ring is，the larger the safety factor is. Slip surface of intact surrounding rock appears at both sides of tunnel；and the stability of rock mass in fracture zone with angle of 45°is the most unfavorable. So the pregrouting treatment is necessary in order to cut down the seepage water. Under this condition，the tunnel lining can be designed according to principle with water pressure.