Study On The Tunnel's Modality Impact Of Changes Of Surrounding Rock Water Content At Loess Tunnel

Loess Plateau distributes widely in our country, many projects all Pass through the loess area. Zhengzhou - Xi'an high-speed dedicated Passenger line has almost 50km tunnel located in the loess stratum, occupied 65% of the entire line .In the loess tunnel, the change of the water content will have great impact on the loess strength and the entire tunnel shape , just because the loess is the rock of the tunnel.With the construction of the tunnel, How to determine the course of the change of the water content and the change of the rock strength, and how to determine the influence caused by the change mentioned above on the tunnel form, are directly related to set up tunnel Advance Support, Excavation Method, Secondary Lining, and to control the deformation of the tunnel and the tunnel surface structures effectively. also it is directly related to the security and economy of the tunnel and the Structures in the ground , so, it is the focus of this Paper.The Paper based on the Zhangmao tunnel in Zhengzhou -Xi'an high-speed dedicated Passenger line, firstly , does the static Triaxial test and Conventional soil test, to get the basic physical and mechanical Parameters of the Zhangmao tunnel loess, with which we can analysis the law of the loess shear strength and the law of the loess compression module with the change of the water content in Zhangmao region. Then , we stabilize finite element model to simulate the change of the tunnel shape in different water content(the nature state, the saturation state , 4% and 8% percent by saturated state)and in different process of the tunnel construction. Finally, we monitor the deformation and the internal force of the tunnel , and make a contrast between the measured data and the simulated data, through all of above , we can draw the law of the change of the loess tunnel shape caused by rock moisture change.With the analysis list above, the law of the tunnel morphological change can be fully understood , besides , the low can adequate more technical data to high standards design and construction in the railway, it is definite value practice.