隧道掌子面附近涌水量预测研究

Research on the Prediction of Water Inflow near Tunnel Face

研究目的:针对二维渗流模型分析隧道掌子面附近渗流场的局限性问题,以掌子面所在平面为分界线,利用反映法将有界含水层用映射原理转变为无界问题,分别构建掌子面前后方涌水简化计算模型。基于流体质量守恒定律、达西定律及线性叠加原理推导涌水量计算公式,并与已有解析公式对比以检验公式的适用性,再对相关参数进行敏感性分析,最后通过与现场实测数据对比检验模型构建的合理性及公式推导的正确性。研究结论:(1)增加注浆圈厚度或降低其渗透性均对减小掌子面前后方涌水量有利,但掌子面后方对注浆圈厚度及渗透系数要求高于掌子面前方;(2)掌子面前后方涌水量均随隧道内缘水头高度的增加而线性减小;(3)有注浆设计时,掌子面前后方理论计算与实测误差分别为12.8%与5.1%,无注浆设计时,掌子面前后方理论计算与实测误差分别为10.7%及6.9%;(4)本研究成果可为隧道掌子面附近涌水量预测提供理论指导,为掌子面前后方加固设计提供理论依据。

Research purposes:To analyze the limitations of the seepage field near the tunnel face with the two-dimensional seepage model,this paper takes the plane of the tunnel face as the dividing line,uses the reflection method to transform the bounded aquifer into an unbounded problem using the mapping principle,and constructs a simplified calculation model of water gushing in front of and behind the tunnel face.Based on the law of conservation of fluid mass,Darcy’s law and linear superposition principle,the calculation formula of water inflow is derived,and compared with the existing analytical formula to verify the applicability of the formula,then sensitivity analysis of related parameters is carried out,and finally by comparison with field measured data the rationality of model construction and the correctness of formula derivation are discussed.Research conclusions:(1)Increasing the thickness of the grouting ring or reducing its permeability is beneficial to reducing the water influx in the front and rear of the face,but the thickness and permeability coefficient of the grouting ring behind the face of the face are higher than those in front of the face.(2)The amount of water gushing from the front and rear of the tunnel face decreases linearly with the increase of the head height of the inner edge of the tunnel.(3)In the case of grouting design,the theoretical calculation and the actual measurement error of the front and rear of the tunnel face are respectively 12.8%and 5.1%;in the case of no grouting design,the theoretical calculation and actual measurement errors in the front and rear of the tunnel face are 10.7%and 6.9%,respectively.(4)The research results can provide theoretical guidance for the prediction of water inflow near the tunnel face,and provide a theoretical basis for the reinforcement design of the front and rear of the tunnel.