深埋隧道注浆加固围岩非达西渗流场及应力场解析

深埋高水压地质环境下,隧道围岩内部往往伴随出现非达西高速渗流现象,且新奥法理念下的注浆加固围岩是隧道支护体系的重要部分,这2个因素对围岩内部渗流场及应力场的影响不可忽视。为此,建立含有注浆加固围岩的两场耦合解析模型,基于有效应力原理严格推导隧道围岩非达西渗流场及有效应力场解析解,通过与达西渗流的对比说明非达西渗流特征并验证解析解的有效性;根据解析理论对非达西渗流效应及注浆加固对围岩有效应力场的影响规律进行分析。研究结果表明:非达西渗流效应的主要影响范围为隧道开挖半径至3倍注浆半径内围岩,注浆加固范围内围岩有效应力相比达西渗流偏大,尤其是环向有效应力;注浆加固前后围岩力学和渗透性质发生改变,使得环向有效应力在加固边界处突变,指向隧道方向大幅增加,注浆范围内围岩有效应力随着加固后弹性模量的增大而升高,随着加固后渗透系数的减小而有所下降;针对需要严格控制排水量的隧道,注浆设计时建议优先降低注浆范围内围岩渗透系数,其次再适当加大注浆范围。研究结果可为深埋高水压隧道注浆加固设计提供理论依据。

Analysis of Non-Darcy Seepage Field and Stress Field of Surrounding Rock Strengthened by Grouting in Deep Buried Tunnel

Non-Darcy seepage with high velocity exists in deep buried tunnel engineering, particularly under high hydraulic pressure conditions. Grouting reinforcement is an essential form of support in the new Austrian tunneling method. Thus, non-Darcy seepage and grouting reinforcement should be considered as key factors influencing the seepage field and stress field of the surrounding rock. Therefore, an analytical model including grouted surrounding rock in non-Darcy seepage was proposed. The characteristics of non-Darcy seepage were illustrated and compared with those of the Darcy seepage, and the validity of the analytical solution was verified. The influence of the non-Darcy seepage and grouting reinforcement on the surrounding rock can be summarized as follows:the range of influence of non-Darcy seepage from the tunneling radius reaches three times the grouting radius. The effective stress of grouted rock is larger with non-Darcy law, particularly the hoop effective stress; the mechanical and permeability characteristics of the surrounding rock change after grouting, thus, the hoop effective stress increases rapidly towards the tunnel. After the grouting reinforcement, the effective stress of the grouted surrounding rock increases with an increase in the elastic modulus and decreases with a decrease in the permeability coefficient; in the tunnel grouting design with strict drainage control, the permeability coefficient should be reduced first, and then the grouting scope should be appropriately increased. The above conclusions provide a theoretical basis for the grouting design of deep buried tunnels under high hydraulic pressure conditions.