隧道透水性衬砌环渗透系数合理取值与工程措施探讨

应用地下深埋隧道渗流场和考虑渗透体积力的弹塑性解,结合某工程实例分析衬砌与围岩渗透系数不同比值对隧道渗流场、渗漏流量、塑性区、位移和衬砌围岩压力等影响规律,探讨透水性衬砌的可行性和合理渗透系数取值。实例分析表明,当衬砌为不透水材料时,洞周围岩中孔隙水压、塑性区、塑性区边缘的位移和衬砌承受的围岩压力均最大；若稍增加衬砌渗透性,则孔隙水压、塑性区、塑性区边缘的位移和衬砌承受的围岩压力迅速减小；随衬砌渗透系数与围岩渗透系数比值的逐渐增大,趋于稳定值。分析结果进一步表明,采用透水性衬砌是可行的,且当衬砌渗透系数与围岩渗透系数比值等于或大于1.0时较为合理。最后,针对洞周环境要求的渗流量以及钢筋混凝土衬砌的耐久性问题提出衬砌环的设计思想,并探讨具体工程措施,以便工程设计参考。

Reasonable permeability coefficient and engineering measures of concrete lining circle

The analytical results of seepage fields and the elasto-plastic solutions considering seepage force are adopted to study the feasibility of permeable concrete lining and its reasonable permeability coefficient. The influence laws of seepage field, flow discharge, plastic zone, displacement and rock pressure are analyzed under different permeability coefficient ratios of lining to surrounding rock of free flow pressure tunnel running in a practical project. The results show that the pore water pressure, plastic zone, displacement at the edge of the plastic zone and rock pressure are the maximum when the lining circle is impermeable concrete material. But those values rapidly decrease when the permeability of lining slightly increases, and tend to be constant values with the increase of permeability coefficient ratios of lining circle to surrounding rock. The method of permeable concrete lining in free flow pressure tunnel is feasible, and the reasonable permeability coefficient ratio of lining and surrounding rock is equal to or larger than 1.0. The permeable concrete lining circle structure is proposed for solving the problems of limited flow discharge required by the surrounding water environment and durability of reinforced concrete lining. The design measures are also discussed.