Preliminary Study Of Soil And Water Conservation And Ecological Protection As Well As Waterproof Of Tunnel

In the past, the drainage and waterproof system design of most railway tunnels in China didn't consider the action of external water load based on the principle of unlimited drainage, so a great number of tunnels have the problem of leakage water, some of which are very serious. Especially at the zone which has abundant water and carbonate rock in West China, owing to an inappropriate principle of the drainage and waterproof, water resource is running out and the environment is worsening. It is focused by local and central government. With the development of tunneling technique, and in view of environment protection (especially water environment), a principle of limited drainage on the basis of blocking water has been putting forward.It was researched from the two measures in this paper for the "waterproof and drainage controlled " of the tunnel project, One kind is measures ofwaterproof and drainage controlled, by adding the gate valve on the discharge pipe, achieves the control withdrawal through the adjustment gate valve switch the goal; and another is that have been adopted usually at projects - grouting.The first measureis is to set up the floodgate valve on the drainpipe, when the the water pressure in the drainpipe is lower than the preset water pressure valve, the valve remained closed; on the contrary, when the the water pressure in the drainpipe is higher than the preset water pressure valve, the valve is turned on for drainage decompression. The core of the second measure is, according to the actual situation, to take many lines to defense the groundwater around the tunnel, security layers, " Stops up primarily, limited emission "principle to the design of the drainage tunnel; in the tunnel lining behind the rock in the design of the thickness of the grouting water shutoff must circle to limit the flow of tunnel lining behind the seepage discharge; and then set up drainage measures such as the blind ditch behind the tunnel lining to discharge a part of water that seepages from above.Theoretical analysis, theoretical deduction and numerical analysis are adopted in this paper. The main research contents are as follows: The research of limited emission design system under ecological environmental protection condition; The research of grouting blocking water technique is did by theoretical analysis; Under the design level control premise leads the drainage system as well as the automatic drainage system research; The theory formula of water pressure at the lining back is deduced. To obtain rational lining and build structural pattern under the"limited emission"by using the numerical analysis methods.According to the abov research, the main results of the paper are as follows:1) Less water head height is, more discharge amount is, more permeability coefficient is, and external water pressure is less.2) The aim of controlling drainage is obtained by adopting grouting blocking water and the structure consisted by grouting sphere for water plugging, primary support, sysytem for waterproof and drainage, secondary lining in turn. And drainage automatic control system also can be adopted to control emissions.3) Circular cross-section structure is the most reasonable cross-section in stress structure, and horseshoe-shaped cross-section structure is worse. Similar ellips(eogival)cross-section structure is suggested by combinating of analysis and study.