High-pressure water-rich stratum water conservancy tunnel new plugging and drainage control design and application research

Abstract

Deeply buried tunnels, even after adopting combined plugging and drainage treatment measures, still face difficulties in simultaneously meeting the dual control requirements of external water pressure and seepage flow standards. Exploring new seepage control method is of significant importance. To this end, the concept of “plugging, collecting, and draining” for seepage control is proposed, and the evolution laws of the surrounding water environment of the lining under different seepage control measures are analyzed. The research shows that grouting for water plugging plays a significant role in reducing the tunnel's seepage flow but is challenging to completely prevent leakage. After implementation, the tunnel exhibits the typical characteristics of “low flow, high water pressure”. Drainage and water collection have a noticeable pressure relief effect but cannot control the seepage flow, making the combined application of plugging, collecting, and draining the key to reducing flow and relieving pressure. When drainage measures are shallow, the pressure relief capability is poor, and when they are deep, the effectiveness of grouting for water plugging is weakened, limiting the pressure relief effect in water-rich and high-pressure strata. By setting up a collection layer, the seepage channels around the lining can be effectively dredged, which does not affect the grouting sealing and significantly improves the drainage and pressure relief effect. In cases of partial blockage of drainage holes or non-full-section drainage, the design of plugging, collecting, and draining can provide channels for local seepage and water pressure dissipation behind the lining, thus avoiding the lining bias effect. The new plugging, collecting, and draining measures can offer a new approach for the design of seepage control under high external water pressure in water-rich strata.

Keywords

hydraulic tunnel / water-rich stratum / plugging,collecting,and draining design / external water pressure / seepage flow rate