Research Of Tunnel Construction Technologies In Old Loessial Soil Area

With the rapid development of social economy and expansion of expressway construction, the overall length of express way across loessial area of northern Shanxi increases every year and the construction of tunnels in the old loessial area becomes a critical project. Due to the characteristics such as wet subside loess,dilatability of old loess, the construction techniques of crossing tunnels in the old loessial area are particular. The construction of tunnels in the old loessial water-rich stratum under the water table is obviously unique. How to solve the problem of getting in the tunnel, the problem of supporting and protection in digging and transfiguration detection and control are the crucial to guarantee construction safety and structure stability.With the old loessial area tunnel, Hanzhai Tunnel in the Seventh Contract Segment of Huang-Yan Express Way as its project background, this dissertation investigated the tunnel construction scheme, main construction techniques, monitoring survey, detection techniques for special geological parts and improvement of support structure in the geological conditions of old loess. Then the detection data and finite element analysis by Sap2000 are compared and at last a summarization and conclusion was obtained on the construction of tunnels in the old loessial area. In geological sections in bad conditions, combined with monitoring survey to observe the supporting structure's convergence transfiguration, finite element analysis software SAP2000 as well as the field measuration data was used to continuously fit the actual wall rock pressure in tunnels, calculate, inspect and design in turn the strength and stiffness of the tunnel supporting structure, and then estimate the stability of the supporting structure. On the basis of the above work, adjust and improve the construction scheme if necessary.