Study On The Influence Of Special Geology Of A Railway Tunnel In Southwestern Shanxi On Tunnel Diseases

A railway tunnel in southwestern Shanxi is located in the southwestern Shanxi Province and is designed as a double-hole single-line tunnel.After the tunnel was officially put into operation in 2015,tunnel diseases soon appeared.In 2015,2016 and 2017,lining cracks and track uplifts were found.After several remediations,there were still recurrences,which were gradually deteriorating and seriously threatened driving safety.In this paper,aiming at the situation that the tunnel disease has been repeatedly rectified,the impact of the complex special geological environment on the tunnel is comprehensively considered,and the mechanism of the tunnel disease is analyzed and identified through numerical simulation,model test,expansion test and rheological test,put forward reasonable control measures,evaluate and predict disease development trends.The particularity of the tunnel lies in the fact that the special stratum is expansive and corrosive,the geological structure is conducive to groundwater seepage,the existence of a goaf above the tunnel,and other adverse factors,which have a complex impact on the tunnel disease.This paper mainly finds out the lithology and distribution law of the stratum in the tunnel area and the tectonic stress environment and evolution law of the tunnel area through the methods of data investigation,field investigation,routine experiment and numerical simulation.Combined with the geological structural characteristics of the tunnel,especially the adverse effects of anticlines and faults on groundwater seepage,the characteristics of underground water flow field and its evolution before and after the construction of the tunnel,as well as the chemical properties of groundwater in the mined-out area and the influence of the flow characteristics on the tunnel disease are analyzed.Combined with the development characteristics and distribution law of the disease,the relationship between the tectonic stress field and seepage field and the tunnel disease is analyzed to find out the main controlling factors affecting the disease.Through research and analysis,it can be concluded that the geological structure of the tunnel site area is complex,the regional in-situ stress is not favorable to the stability of the tunnel,the distribution of gypsum-bearing rocks is extremely irregular,and the groundwater quality and water volume change greatly after the tunnel penetrates.The solution breccia is softened,swelled and corroded by water,the surrounding rock is degraded,and the groundwater seepage field change is unfavorable to the stability of the tunnel.The surrounding rock of the tunnel has extremely complicated engineering geological characteristics..