Abstract:

Experimental study is made on 5 construction methods of large crosssection loess tunnels, including CRD method, doubleside drift method, CD method, corereserved bench method and doublelayersupport bench method, with Qindong tunnel, Tongluochuan tunnel and Gaoqiao tunnel on ZhengzhouXi’an passengerdedicated line as examples. The mechanical and deformation characteristics of the tunnels constructed by different construction methods are analyzed on basis of site measurement and data analysis. Conclusions drawn are as follows: the deformation of the loess tunnel is featured with significant vertical displacement, and the deformation is significantly affected by the closure distance and the support rigidity; The analysis on the ground surface settlement control effect shows that the shaped steel is under significant pressure and the bolt is under small force; The characteristic curves of the pressure of the surrounding rock under different depths are gained; The measurement of the contact pressure indicates that the doublelayer support structure, which has larger rigidity, has smaller contact pressure than the singlelayer support. In the end, compressive evaluation is made on the applicability of the construction methods studied. 

Key words: large crosssection loess tunnel, ZhengzhouXi’an passengerdedicated line, CRD method, doubleside drift method, CD method, corereserved bench method, doublelayersupport bench method, mechanical characteristics, deformation characteristics