压力隧洞衬砌结构型式选择准则

为了从渗透角度给出压力隧洞衬砌结构型式的选择准则,采用渗流-应力-开裂耦合分析模型,进行一系列组合工况下的压力隧洞内水外渗分析,计算得到在不同工况下不同内水压力时的压力隧洞综合透水率.以综合透水率作为判断隧洞是否渗透破坏的标准,建立破坏内水压力与围岩综合抗渗指标的关系,拟合出不同容许吕荣值对应的破坏内水压力与围岩综合抗渗指标的关系曲线,作为钢筋混凝土衬砌与钢板衬砌以及不衬砌与钢筋混凝土衬砌的分界线.研究结果表明,当围岩综合抗渗指标<25时,必须采用钢筋混凝土或钢板衬砌；当围岩综合抗渗指标较大时,对低水头电站压力隧洞可不衬砌.

Selection criteria for lining structure type of pressure tunnel

The inner water exosmosis analysis of pressure tunnel under a series of cases was conducted by using the seepage-stress-crack coupling numerical model in order to propose selection criteria for the lining structure type of pressure tunnel in view of permeability. The comprehensive water permeability of pressure tunnel under different cases and different inner water pressure values was obtained. Relationships between inner water pressure and comprehensive permeability index were established by using the comprehensive water permeability as the seepage failure standard of pressure tunnel. The relationship curves between inner water pressure and comprehensive permeability index for different allowed Lugeon values were fitted out. The curves can be taken as the boundaries among shotcrete-bolt, reinforced concrete and steel lining. Results show that reinforced concrete or steel lining is needed for the tunnel when the rock comprehensive permeability index is less than 25; no lining is needed for tunnel of low-head power plants when the rock comprehensive permeability index is large．