复合式衬砌隧道防排水设计几个问题探讨

为了防止和减少隧道渗漏水病害，通过分析复合式衬砌隧道防排水的现状和存在的主要问题，研究隧道排水量和水压力控制值分级、上下分离的防排水体系、围岩防水能力、防水层和二次衬砌混凝土整体防水效果检验评价等，并对防排水系统的设计和参数选择提出以下建议： 1）对于采用复合式衬砌的隧道，如果能满足环境保护及使用功能要求，其全隧道排水量宜控制在1.0 m3/（m·d）〖JP〗以内，二次衬砌背后承受的水压力最大宜控制在1.0 MPa以内； 2）为了减少隧道渗漏水发生的概率，并保证隧道结构的稳定，可考虑将拱、墙防排水体系和仰拱防排水体系分开设置，拱部、侧墙部位的渗水直接排入侧沟，仰拱部位的水主要通过纵向中心排水盲管排出，当水压力高时，通过与中心排水盲管连通的横向排水管将水引入新增的侧沟，并通过在横向排水管出水口安装的阀门进行限量排放； 3）通过地面隔离墙（咬和桩）、地面注浆、洞内注浆、旋喷、超前管棚、超前管幕、施作双层衬砌等措施，阻断和减小来水通道，提高地层强度和完整性，降低隧道涌水量和衬砌背后的水压力，并降低大量排水对运营和环境的不利影响。

Discussion on Several Issues about Waterproofing andDrainage Design for Composite Lining Tunnel

In this paper, the state of art and existing problems of waterproofing and drainage of composite lining tunnel are analyzed. And then the grading of control values of drainage volume and water pressure, separated waterproofing and drainage system, waterproofing capacity of surrounding rocks, and the integral waterproofing effect of waterproof layer and secondary lining concrete are studied. Finally, some suggestions in terms of design and parameters selection for waterproofing and drainage system are proposed as follows: (1) For the composite lining tunnel without special environmental and functional requirements, the drainage volume of the whole tunnel should be controlled within 1.0 m3/（m·d）, and the maximum water pressure behind secondary lining should be controlled within 1.0 MPa. (2) In order to reduce the occurrence of water leakage and guarantee the tunnel structural safety, the drainage system of arch and sidewall and that of invert should be separately arranged. The seeping water from arch and sidewall can be drained from side ditch, and that from invert can be drained from longitudinal central drainage dead pipe. When the water pressure is high, the water can be drained from longitudinal central drainage dead pipe to additional side ditch by horizontal drainage pipe, and the water drainage volume can be controlled by valve on horizontal drainage pipe. (3) By adopting measures such as ground separation wall(secant pile), surface grouting, grouting in tunnel, jet grouting, advance pipe roof, advance pipe curtain, double layer lining, etc., the water leakage can be reduced or even sealed, so as to guarantee the ground strength and integrity, reduce the water inrush volume and water pressure behind lining, and further reduce the adverse influence of water drainage of tunnel on operation and environment.