高水压富水区隧道限排衬砌注浆圈合理参数研究

海底隧道深埋于海水以下,处于高水压富水区,隧道结构设计时需要考虑外水压力,如果采用"堵水限排"的防排水设计原则,能够以较小的排水量显著降低作用在衬砌上的外水压力,从而使隧道结构设计更加经济。注浆圈合理参数的确定是"堵水限排"的核心问题。基于穿越高水压富水岩溶区的圆梁山隧道工程,通过理论计算和分析,得到了注浆圈参数变化对隧道涌水量和衬砌外水压力的影响规律;提出了隧道排水率的概念,分析了隧道排水率与衬砌外水压力之间的关系。在此基础上提出了确定注浆圈合理参数的方法和程序,给出了圆梁山隧道注浆圈的合理参数值,并在现场得以应用,取得了理想的效果,注浆后实测隧道涌水量与理论计算值基本一致。研究结果表明:衬砌外水压力折减系数取决于隧道排水率,只有当隧道排水系统能够将渗透到衬砌背后的地下水全部排出时,衬砌外水压力才能完全消除;注浆圈的作用不是分担衬砌外水压力,而是通过封堵地下水降低隧道涌水量,从而以较小的排水量可显著降低甚至消除衬砌的外水压力。研究成果对类似高水压富水区以及海底隧道防排水设计具有一定的参考价值和借鉴作用。

STUDY ON APPROPRIATE PARAMETERS OF GROUTING CIRCLE FOR TUNNELS WITH LIMITING DISCHARGE LINING IN HIGH WATER PRESSURE AND WATER-ENRICHED REGION

Subsea tunnels are located deeply under sea with high groundwater pressure. Therefore,external water pressure on lining should be considered when designing tunnel structure. With the idea of blocking groundwater and limiting discharge,external water pressure on tunnel lining can be reduced remarkably with low discharge, so tunnel structure design will be more economical. To find the appropriate parameters of grouting circle is the key issue to perfectly blocking groundwater and limiting discharge. Based on the case of Yuanliangshan tunnel located at high water pressure and water-enriched karst region,the basic regulations of the effects of grouting circle on tunnel gushing water and external water pressure on lining are studied by theoretical calculation and analysis. The concept of tunnel discharge ratio is put forward;and the relation between tunnel and external water pressure on lining is analyzed. Based on the above-mentioned research results,the method and program for choosing appropriate parameters of grouting circle are proposed;and the appropriate parameters of grouting circle for Yuanliangshan tunnel are given. The parameters of grouting circle are adopted;and satisfactory effects are achieved. The monitoring amount of gushing water after grouting is basically identical with theoretically calculated value. Research results indicate that the reduction coefficient of external water pressure on lining is decided by tunnel discharge ratio;it will be zero only when water seepage behind tunnel lining can be discharged absolutely,or there is external water pressure on lining. The effects of grouting circle will not share the external water pressure with tunnel lining,but block groundwater and reduce the external water pressure on lining remarkably with low discharge. The research results will provide references to tunnel waterproofing and drainage system design in high water pressure and water-enriched regions including subsea regions.