高压大流量地下水隧道开挖超前帷幕注浆参数研究

Study on parameters of advanced curtain grouting for tunneling with high pressure and large flow-rate groundwater

锦屏水电站锦屏山隧道开挖中面临高压大流量地下水、且富水地段长(约占隧道全长的40%)的难题。为安全、可靠地进行隧道施工,以注浆材料的适应性、超前帷幕注浆的参数及工艺为研究对象,对浆液做了大量配合比试验,分析其流动性、物理力学性能和凝结时间。研究结果表明:用纯水泥进行单液浆帷幕注浆,其可注性好,可大大地提高注浆加固效果;纯水泥+双液浆对局部小的渗漏水具有很好的封堵效果。对于低于2 MPa的压力水,注浆压力取2~3倍的静水压力;对于高于5 MPa的压力水,注浆压力取净水压力加2~3 MPa。对于在2~5 MPa之间的压力水,注浆压力可灵活选取,但不宜超过7 MPa,注浆应采用孔内循环灌注的方式。地下水发生在断层破碎带时,超前帷幕注浆宜采用全断面帷幕;若出水段以溶蚀裂隙、断层、管道为主宜采用有针对性的局部超前帷幕注浆。该技术成功解决了锦屏山隧道高压大流量地下水封堵的难题,对富水地层地下隧洞施工具有重要参考价值。

During the excavation of Jinpingshan Tunnel for Jinping Hydropower Station, the problem of high pressure and large flow-rate groundwater is faced, and the water-abundant section is longer （ about 40% of the total length of the tunnel）. The a- daptability of the grouting materials and the parameters of the advanced curtain grouting as well as its technology are taken as the study objective, and then large number of mixing ratio experiments on the grouting slurry are made for analyzing its fluidity, physical and mechanical properties and setting time, so as to safely and reliably excavate the tunnel. The study result shows that if the pure cement is used for the single-slurry curtain grouting, better groutability can be obtained and the strengthening effect from the grouting is to be largely enhanced, while the cement ＋ bi-slurry grouting has an excellent sealing effect for the small local leakage as well. For the pressure water with the pressure lower than 2 MPa, the grouting pressure of 2 - 3 times of the hydrostatic pressure is taken, while the hydrostatic pressure plus 2 - 3 MPa is taken as the grouting pressure for the pressure water higher than 5MPa. For the pressure water with the pressure between 2 MPa and 5 MPa, the grouting pressure can be flexibly se- lected, but it is better not over 7 MPa and the in-hole circulation grouting must be adopted as well. When groundwater occurs at fault fracture zone, the full-section advanced curtain grouting is better to be adopted, while if the water-gushing section mainly consists of erosion fissures, faults or pipeline, pertinent local advanced curtain grouting is better to be used. The problem from the sealing of high pressure and large flow-rate ground water during the construction of Jinpingshan Tunnel is successfully solved by this technology; which has an important reference value for the tunneling through water-abundant strata.