富水地区隧洞衬砌开裂的外水 压力原因分析

某无压输水隧洞在富水地区修建，检修时发现混凝土衬砌出现严重裂缝，与围岩之间存在连续脱空。为此，采用三维有限元法，按照渗流场变化历史对隧洞渗流和应力场进行了模拟计算，结果表明，外水压力可能是造成衬砌开裂的原因，并提出了降低衬砌外水压力和拉应力的处理措施建议。现场监测表明本文的计算方案和成果合理。

Analysis on tunnel lining cracking caused by external water pressure in water-rich area

During the maintenance of a free-flow tunnel built in a water-rich area,severe cracks of the concrete lining with continuous disengagement between both the lining and the surrounding rock are found;for which,the seepage and stress field around the tunnel are simulated herein with the 3-D finite element method in accordance with variation process of the seepage field.The result shows that the external water pressure is possibly to be the cause of the cracking.Therefore,the relevant treatment measures and suggestions of lowering the external water pressure and tension stress of the lining are put forward.The in situ observation shows that the calculation scheme given herein and the results are reasonable.