Coupling Analysis Of Seepage Stress In Surrounding Rock Failure Process Of Deep Tunnel In Karst Area

In recent years, the rapid economic development of China, with the constant increasing of development and utilization of underground space, more and more railway and highway engineering, hydropower project, the south-north water diversion project, and all kinds of mining engineering is inseparable from the tunnel. The southwestern region of karst development, so that the construction of the tunnel inevitably encountered adverse geological problems of karst caves, karst water, so that an increase in the degree of difficulty of construction. Deep karst features are more complex. Complex karst area, caves tend to high water pressure, joint special geological conditions fissures, faults, etc. Tunnel construction in karst area, karst cave filled with high-pressure water, when driving to the cave near the edge of cave position, cave in the high-pressure water to a rapid influx of the tunnel, causing water inrush accident, and some even lead to cracking of the surface subsidence. Therefore, the study of the pressure of karst cave on the stability of the tunnel surrounding rock has important practical significance.In this paper, use the real coupling analysis system RFPA2D-Flow, karst area near a water filled Cave Tunnel as the main research object, aiming at the karst area of deep buried tunnel surrounding the water filled cave obtained the following conclusions:(1)The numerical model of water filled caverns with different water pressure and different distance from the tunnel are analyzed, analysis results show that the water pressure in the cave will accelerate the increase in the tunnel surrounding rock failure. Under the same loading conditions, the greater the pressure, rock between caverns and tunnels the more prone to damage, and the cracks first appeared in larger hydraulic loading model. Under the same load conditions, the smaller distance between the caverns and tunnels, the more prone to causing water inrush.(2)Analyze the influence of cave filled with water which is in the bottom of tunnel surrounding rock of the fractured rock mass, analysis results show that in rock fracture, crack angle are different, but hydraulic crack propagation is basically the same, were along the fissure approach to extended(3)When the cave on the top, side and bottom of the tunnel. Under the same loading condition, the water filled cave in the side of the tunnel is the first to run through the water, and the bottom of the cave is the second, and the top of the cave finally break down. Under the same loading conditions, the combination of the karst cave is more likely to occur through the tunnel.On the basis of theoretical analysis and numerical experiments, the failure process of deep tunnel is analyzed, combined with the engineering example Analysis of the minimum safety thickness. To ensure that the process of building the tunnel to avoid water inrush due to water-filled caves and tunnels had nearly caused. In order to ensure the water inrush accident caused by the water filled cave nearly tunnel. Through the analysis of this article, drawn to certain rules, provide a useful reference for the construction of karst area.