Abstract
Water inrush of tunnel is one of the most common geological disasters in the karst strata in China. Aiming at the rock mass with a quasi-masonry structure in the water-resistant strata between karst cavity with high pressure water and tunnel and the shortcomings of theoretical analysis, traditional numerical simulation, and physics model test for describing and reflecting this special structure of rock mass, a Discrete Element Method considering the fluid-solid coupling effect and structural characteristics of rock mass is employed to study the disaster process of water inrush and the evolutionary characteristics of catastrophe information like seepage pressure and displacement under condition of different karst water pressure, tunnel depth, and lateral pressure coefficient. Research results show the following: (1) the seepage pressure and displacement increase with the increase of kart water pressure. The seepage pressure demonstrates a decreasing state from top to bottom in water-resistant strata, and the time of arrival to a stable value for the seepage pressure shows the time effect. (2) The larger the tunnel depth, the greater the coalescence and distribution scope of fracture and the more likely the water inrush to occur in a short time. The stability of water-resistant strata decreases on the whole with the growth of tunnel depth. (3) The increase of lateral pressure coefficient can restrain the fracture development and strengthen stability. The fracture state is significantly influenced by a lateral pressure coefficient. The results of numerical simulation are consistent with those obtained by a model test. Research and analysis based on energy are a promising train of thought for studying the disaster process of water inrush in a karst tunnel.
Highlights
Since the 21st century, with the rapid advancement of west development strategy of Chinese national economy, the focus of tunnel construction has gradually shifted to the Western Mountain and karst area
(2) The larger the tunnel depth, the greater the coalescence and distribution scope of fracture and the more likely the water inrush to occur in a short time
The results of this paper show that karst water pressure, tunnel depth, and lateral pressure coefficient have obvious effects on the water-resistant strata stability
Summary
Since the 21st century, with the rapid advancement of west development strategy of Chinese national economy, the focus of tunnel construction has gradually shifted to the Western Mountain and karst area. Lots of scholars have done many researches on disaster mechanism of water inrush and catastrophe information characteristics by theoretical analysis, numerical simulation, and physical model tests up to now. Pan et al [22] conducted a solid-fluid coupling model tests on lagging water inrush of karst tunnel and researched the evolutionary process of disaster information under different karst water pressures. Numerical simulation is an effective and convenient tool for the simulation of disaster process of the water-resistant strata and water inrush with some unique advantages compared with theoretical analysis method and physical model testing method. The new method based on the DEM (UDEC) and fictitious joint technology is adopted to really simulate the disaster process of water-resistant strata under the combined effect of different karst water pressure, tunnel depth, and lateral pressure coefficient [23, 24]. The achievements are of great significance for early warning and prevention for water inrush of karst tunnel
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