The Theory And Application Of Dewatering Inside Tunnel In The Water-enriched Soft Strata

Some tunnels subject to restrictions on the surface and terrain conditions when mining method used in the construction of tunnels in the water-enriched soft strata and they must use the dewatering inside the cave to lower the groundwater level. Horizontal wells and oblique wells are common type well because of the construction, but now research in this area is rarely. This paper studies the theory of dewatering inside the cave by the method of mathematical analysis based on the theory of groundwater seepage. The main results as follows:(1) In order to simplify the derivation of equations, the dewatering wells are assumed to be a point in the dewatering inside the tunnel, and then the stratawater seepage will change from the original three-dimensional into a two-dimensional field. According to this hypothesis, we deduced the flow equation of the level of pressure full well, the level of free surface full well and bottom water uncomplete wells. At the same time, using the flow equation deduced the formula of permeability of aquifer and the radius of influence.(2) In some specific projects, such as the aquifer is non-homogeneous layered structure, group wells instead just one in the cave inside dewatering and other situations, the dewatering formula have been also provided in this paper.(3)In addition to that, this paper discusses the design principles of dewatering inside the tunnel and the hydraulic loss of stratawater in th horizontal dewatering well or the Oblique dewatering well. And we get some useful results.(4) With previous research results, we established the plan preliminary design of rainfall dewatering inside the tunnel for the TaoShuPing Tunnel integrated the horizontal dewatering well and the oblique dewatering well.The paper's result of the research of dewatering inside the cave will have the reference value in this theory's development and the design philosophy or the construction technology.