Application Of Shield Technology In Loess Tunnel Construction

Analyzing the fundamental, actuality development and application of shield tunnel construction technology, the rationality of applying shield to loess tunnels, main problems which may fall across and the alternative solved schemes were researched in this paper. Based on brief introductions of currently applied shield types, which shield types can apply to loess tunnels was researched in this paper. Analyzed the projection application of shield, the liner structure and the structure analyzing methods which is applicable to loess tunnel were researched deeply.According to the project practice of shield construction in the fifth tunnel of LuoHuiQu Irrigation Area, many problems were taken into researching such as applicable conditions of shield construction technology in loess area, how to select the shield type, how to define the load of the liner, analyzed methods of the structure and how to select the design index. Based on mainly research of shield construction technology in loess tunnel, some resolved methods of special questions were put forward such as controlling the shield orientation, stabilization of excavated surface, crossing collapse body.The mainly conclusions in this paper were listed .as follow. Firstly, in the conditions of extrusive stabilization questions of soil level, very long tunnelline and very high need of surface settlement, there are very good technical applicability and economical rationality of applying the shield technology to loess tunnels. Secondly, the mainly problems of applying the shield technology to loess tunnels are rational predigestion of shield and reducing the project cost in according to the loess property. Thirdly, in the condition of shield construction, the deformation law of loess and testing methods need to be further researched.