Research On The Stability Of Arch Foot In Soft Rock Tunnel

With the rapid development of China’s railway industry, in order to reduce transport distances, the construction process will through the mountains inevitably,and tunnels such as one of the most convenient way to build so many. Wherein for soft rock tunnel, currently supporting more consideration for the wet-mix shotcrete of high early age strength performance, the strength of the concrete to harden directly after the final value of design primary support, and strength of concrete as a material increase over time, so the design seems to be wrong. Currently, the excavation methods of soft surrounding rock tunnel are mostly fractional step method of excavation and other construction method, wherein the method of excavation also includes blasting and non-blasting, blasting excavation and non-blasting excavation for soft rock tunnel influence is a problem worthy of study.In this paper, the engineering background is double high-speed railway tunnel ofⅣ 、 Ⅴ Grade Rock, the numerical simulation of initial support with shotcrete concrete hardening characteristics and without considering hardening characteristics,approximate simulation of blasting and non-blasting excavation influence of the tunnel stability.(1) the actual situation of Dapingdi tunnel, select the level of the surrounding rock and tunnel parameters for numerical simulation basis.(2) resources for the selected wet sprayed concrete early strength hardening function, and consider the case of the steel arch.(3) for hardening tunnel excavation numerical simulation analysis considering hardening characteristics without considering hardening characteristics and stabilizing influence of the tunnel.(4) selected range of rock damage and damage values caused by blasting.numerical simulation of blasting and non-blasting process, comparative analysis of the different effects produced on the tunnel stability.