Abstract:

The current formula for deepburied surrounding rock pressure in Code for Design on Tunnel of Railway does not take the bearing capacity of the surrounding rock of the tunnel arch and the effect of advanced support into consideration, and the calculated load is overlarge. In order to verify the actual compressive load of surrounding rock on primary support structure of deep tunnel, the deformation behavior of surrounding rocks and structure of SanmenxiaJingmen Section on Menghua Railway is discussed by analyzing deformation monitoring data of surrounding rocks; and the loadstructure plane finite element model is established and the compressive load of surrounding rock is deduced by displacement analysis method of crown top settlement combined with horizontal convergence. The analytical results show that: 1) The surrounding rock load obtained by doubleline tunnel back analysis is about 70.7%-76.5% of the calculated value obtained by formula of relevant standards. 2) The surrounding rock load obtained by singleline tunnel back analysis is about 88.8%-93.1% of the calculated value obtained by formula of relevant standards. The study results can provide guidance for site construction and support structure design and optimization of Menghua Railway.

Key words: Menghua Railway, deep tunnel, softandweak surrounding rock, surrounding rock pressure, displacement back analysis, tunnel load