| With the continuous development of China ’ s transportation industry,multi-level railway network has been basically formed.In the process of railway tunnel construction,the problems faced by high ground stress soft rock tunnels are becoming more and more complex,which not only threatens the safety of tunnel construction,but also has certain hidden dangers in the later operation process.Therefore,the study of high ground stress soft rock tunnel support method has practical engineering significance.(1)Based on the Kangding No.2 tunnel project,this paper first introduces the engineering geological conditions of Kangding No.2 tunnel,and analyzes the stress,deformation characteristics and support scheme of the tunnel.Kangding No.2 tunnel is located in the high geostress area.The geological structure is complex and the lithology is mainly soft and weak rock and soil.The deformation of the tunnel does not tend to converge after excavation.The main contents of this paper are the deformation of soft rock tunnel with high geostress and the analysis of the support scheme.Numerical simulation and theoretical analysis are used.(2)The deformation characteristics of soft rock with high ground stress are summarized,and the supporting mechanism of prestressed anchor cable is analyzed.Through the simulation analysis,it is found that under the condition of high ground stress,the use of prestressed anchor cable will give full play to the bearing capacity of surrounding rock.At the same time,the supporting structure is optimized to form beam-arch composite structure under the action of prestress,which ensures the stability of surrounding rock and prevents deformation and failure.At the same time,the supporting structure is optimized to form composite beam and arch structure under the action of prestress,which ensures the stability of surrounding rock and prevents deformation and failure.(3)The influence of different physical parameters of rock mass on deformation is simulated by Midas / GTS software,and the influence range of physical parameters of rock mass is obtained after numerical simulation analysis.The numerical simulation method is used to compare the influence of mixing,bolt and prestressed anchor cable on the deformation and displacement of surrounding rock.Through the displacement of surrounding rock,the advantage of prestressed anchor cable as a way to control the deformation of soft rock tunnel with high geostress is obtained.(4)The design parameters such as the length of prestressed anchor cable,pre-tightening force and circumferential spacing are optimized and simulated.The anchoring method of prestressed anchor bolt-cable combined support was proposed and compared with that of spray mixing and prestressed anchor bolt support.It was concluded that the deformation control effect of prestressed anchor bolt-cable combined support was the best under the condition of high geostress soft rock. |
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