Research On Stability Analysis Of Soft Rock And Control Measures For Xiaozhai Tunnel In Yungui Railway

With the rapid development of China’s western region and the cause of infrastructure to further advance, the rapid development of railway,lots of railway tunnels been built in china in recent years.The surrounding rock has the characteristics of poor stability and deformation is difficult to control when a tunnel is constructed in soft rock,its has great impact on the tunnel’s construction.So research on deformation characteristics and control measures of the soft rock is very important.Author studied on the soft rock of Xiaozhai tunnel,analysis and summarize its deformation characteristics with the monitoring data in construction process,analysis the stability and main reasons for the large deformation of Xiaozhai tunnel’s soft rock.Summarize the control concepts for large deformation of soft rock tunnel,establish the integrated control system of large deformation.Propose more accurate deformation control measures to guide the construction.And simulate construction in soft rock by elastic-plastic finite element analysis method,demonstrate the reasonableness of the proposed that deformation control measures.The main research achievements as follows.(1) Author repute that although the rock ultimately be stable but it will occur large deformation through analysis the measuring data in construction process of typical section for Xiaozhai tunnel.Its main deformation characteristics as follows:large deformation,the deformation of initial stage is large,the duration of deform is long,the deformation of vault always large than the surrounding deformation.Vault settlement mainly affected by the excavation of the upper step.The impact on the surrounding deformation are quite by the excavation of the upper and down step.The rate of rock deformation release is very fast when less than10m from the excavation face. The rate of rock deformation release decrease with the increase of distance from the excavation face.The rock deformation almost unchanged when the distance reach2times hole diameter from the excavation face.(2) Author repute that soft rock,not timely design change and irregularities construction is the main reasons for the large deformation of Xiaozhai tunnel’s soft rock through analysis the reasons from geological factors, design factors and construction factors. (3) Establish the integrated control system of the tunnel’s large deformation in soft rock by summary the control concepts for large deformation.Take appropriate measures to control large deformation of Xiaozhai tunnel,such as advance support, excavation methods, support measures,monitoring and measurement.And through simulate construction to demonstrate the reasonableness of the proposed that deformation control measures.