Study On Seepage Failure Mechanisim And Risk Control Of Water Inrush Induced By Filled Disaster Structure In Deep-long Tunnel And Engineering Applications

The tunnel and underground engineering construction in China has larger-scale, more quantity and difficulties than in the other countries. The nation infrastructure construction tends to the mountain area and karst area with complex geological conditions. Accordingly, the water inrush disaster comes out. The water inrush always bursts accidentally, presses hugely, flows massively, and shows multiple types. This problem is world-class project difficulty.In this paper, based on the deep long tunnels of Three Gorges reservoir area expressway and Yiba expressway, the water inrush mechanism and risk control of filling type disaster-causing structure was researched, using theoretical analysis, numerical simulation, laboratory experiment, large fluid-solid coupling model test, software development, and field test. Some research results of important theoretical value and project significance were summarized, listed as follows:(1) Four classical water inrush and mud inrush types were divided, according to lots of water inrush and mud inrush cases at home and abroad. The corresponding classical geological model was proposed:the disaster source, water inrush channel, and water inrush prevention structure. The typically water inrush disaster source occurrence characteristic was summed up. The index system and attribute recognition model of water inrush disaster source disaster-pregnant judgment was set up.(2) By introducing the source term concept "the movable particles in the filling body translate into moved particles, the filling body particles seepage model was established, according to Archimedes principle and Darcy law. The movable particle in the filling body loss amount expression was deduced, the relationship of pore water velocity, porosity, permeability coefficient was expressed. Large diameter filled-type disaster structure solid-fluid coupling device was manufactured. This device showed the change law of velocity, seepage gradient, particle drop-out rate, porosity.(3) Based on mud water two-phase mixture in the filling body non Newtonian fluid characteristic, Bingham slurry mixed fluid constitutive equation showed the relationship of velocity in tunnel distribution regularity and pressure flow. The mud water two-phase mixture critical flow velocity was deduced based on Hedstrom. The distinguishing flow regime of mud fluid from laminar flow to turbulence was established. (4) According to Jijiapo Tunnel fracture water inrush disaster, which was high steep and declining, the basic physical and mechanical properties of tunnel surrounding rock and filling body was tested. Based on the test results, new similar solid-fluid coupling material to the surrounding rock and filling body were developed. Filling body seepage failure Evolution was revealed, using3D visual water inrush model test system to test filled-type fracture retaining water to seepage failure. This experiment simulated the whole process of the filling body seepage failure causing to water inrush and mud inrush.(5) According to hundreds of karst tunnel water inrush cases in recent50years, the tunnel water inrush environment and factors were analyzed. Choosing typical impact factor, gradual risk dynamic evaluation model and methods from investigation to construction were established. The water inrush risk could be modified according to the real-time information in the construction.(6) The program was interface friendly, operated easily, evaluated dynamic and throughout. A new risk management mechanism-construction permission mechanism was proposed. So the construction could be regulated according to the risk dynamic information, it realized the whole part informatization permission construction.(7) The karst tunnel water inrush prevention and control technology system was proposed, its basic principle was karst geology observation and analysis, risk dynamic evaluation and control, water bearing structure positioning and quantitative, quality plan optimization and quality assurance. It included the development characteristics of karst area, the karst water recharge condition, and risk dynamic evaluation, the water containing structure detection, treatment plan optimization, and management quality control. This research was applied in Jigongling Tunnel, Jijiapo Tunnel and so no.