Study On The Mechanical Characteristics And Support Technology Of High Water Pressure Deep Shaft Lining

In the railway tunnels built in the mountainous areas of Southwest China,there are many disasters such as wall caving,collapse and water inrush,which not only affect the construction progress,but also cause casualties and property losses.Therefore,this paper relies on the No.1vertical auxiliary shaft project of Gaoli Gongshan railway tunnel,which is 764.74 m deep and is located in the strongly weathered and weakly weathered mixed granite stratum,and rich in bedrock fissure water.There are many wide cracks in the lining of weak weathered bedrock section and matoumen section.By means of field monitoring and numerical simulation,the mechanical characteristics and support technology of high water pressure deep shaft lining are studied,the main research contents are as follows:(1)Based on the field monitoring data,it is concluded that the surrounding rock pressure on the outside of the shaft lining is symmetrical,and the water pressure is asymmetrical.The asymmetrical water pressure is mainly caused by the uneven development of cracks in the water-rich granite formation and the difference in grouting effects.(2)The load-structure model was established with RFPA software,and the mechanical characteristics and failure mechanism of the shaft lining structure under asymmetric load were revealed.(3)A new method for calculating the safety factor of high water pressure deep shaft lining is proposed,and the ratio of the lining normal service limit state load to the actual load is defined as the lining safety factor.Using this method and the method specified in the "Railway Tunnel Design Code",the safety factors of the shaft lining of each section under asymmetric load were calculated respectively,and the two calculation results were compared and analyzed: the two methods have an effect on the safety of the lining The judgment results are consistent,indicating that the new definition method is more reasonable for calculating the safety factor of the shaft lining.(4)The seepage stress elastoplastic model is established by using RFPA software.The influence of permeability coefficient and thickness of grouting ring on seepage pressure is studied,and the support parameters are optimized.The results show that it is very effective to reduce the osmotic pressure by changing the permeability coefficient and the thickness of the grouting ring,but the effect is better by changing the permeability coefficient.