隧道复合式防排水系统的设计、试验及工程应用

传统隧道防排水系统中，防水板极易因施工控制不当出现破裂，而防水板破裂后，地下水进入防水板与二衬间的空隙中，由于防水板与二衬间缺乏排水通道，地下水将沿衬砌裂缝、施工缝等薄弱环节渗出而形成隧道渗漏水病害。在传统隧道防排水系统中，渗漏水病害治理难度大，维修费用高，针对传统防排水系统存在的不足，提出了一种在隧道防水板与二衬间增设排水板的复合式防排水系统，该系统具有可调节、抗淤堵、易维护等优点。为验证该系统的有效性，采用自主研制的试验装置对复合式防排水系统中所采用的3种土工排水材料（毛细型排水板、凸壳型排水板、土工布）在不同水压及支护压力条件下的排水能力及抗淤堵能力进行了相关试验，并依托某在建隧道工程对不同土工排水材料在隧道复合式防排水系统中的应用效果进行了现场验证。主要研究成果有：①随着支护压力的增加，3种排水材料的排水能力均出现了不同程度的降低，其中，土工布降幅最大，毛细型排水板次之，凸壳型排水板最小；②在固定的水压和2层支护间压力条件下，进行20次浑水排水试验后，土工布排水能力发生大幅下降，毛细型排水板和凸壳型排水板排水能力小幅下降，但凸壳型排水板排水夹杂有泥沙，而毛细型排水板排水为清水，表明其抗淤堵能力较好；③复合式防排水系统的现场试验数据表明，防水板与二衬间增设排水板，具有良好排水泄压的能力，可有效降低衬砌背后水压。复合式防排水系统的研发可为隧道防排水系统设计和渗漏水病害治理提供借鉴。

Design,Test, and Engineering Application of a Composite Waterproof and Drainage System in Tunnels

In a traditional tunnel waterproof and drainage system (WDS), the waterproof board is easily damaged because of improper construction control, resulting in groundwater entering the gap between the waterproof board and the second lining. Groundwater seeps out along weak links, such as cracks and construction joints, in the lining, because there is no drainage channel between the waterproof board and the second lining, and causes water leakage problems in the tunnel. It is difficult to treat the water leakage damage in the traditional tunnel WDS, and the maintenance cost is high. To address the shortcomings of the traditional WDS, a composite WDS with an additional drainage board between the tunnel waterproof board and the second lining is proposed. It has the advantages of adjustability, antiblocking capability, and ease of maintenance. To verify the effectiveness of the system, tests were carried out on the drainage capacity and anti-blocking capacity of three geotechnical drainage materials (capillary drainage board, convex shell drainage board, and geotextile) adopted in the composite WDS. The tests were conducted under different water and support pressures using a self-developed test device. In addition, the application of different geotechnical drainage materials in the composite tunnel WDS was verified on-site at a tunnel project under construction. The main results are as follows. ① For the same value of drainage water pressure, the drainage capacity of the three drainage materials is a decreasing function of the support pressure. The geotextile has the largest drop in the drainage capacity, followed by the capillary drainage board; the convex shell drainage board has the smallest drop. ② For the same values of drainage water and support pressures, the drainage capacity of the geotextile decreases significantly after muddy water drainage tests are performed 20 times, and the drainage capacities of the capillary drainage board and convex shell drainage board decrease slightly. Moreover, the drainage of the convex drainage board is mixed with sand, whereas the drainage of the capillary drainage board is clean water, indicating that the capillary drainage board is better at resisting blockage. ③ The field test data of the composite WDS show that the additional drainage board between the waterproof board and the second lining has good drainage and pressure relief capabilities, and can effectively reduce the water pressure behind the lining. The development of composite WDS can provide a reference for the design of tunnel WDS and the treatment of water leakage.