Study On Surface Subsidence Prediction And Early Warning System Of Cobble Stratum Tunnel

With the improvement of the national economy,China's transportation industry has entered another period of rapid development.Especially in the western development strategy implementation,Tibet transportation enterprise vigorous development,road network extends to the natural conditions,high latitudes and high altitude.As the highest plateau in China,there is inevitably a lot of tunnels running through the steep mountains where traffic is unavoidable.Because of the complex engineering geology of the Tibetan region,there are many technical difficulties in building tunnels here.Rulin,high-speed reconstruction project is a standard niang cover village widely distributed along the tunnel pebble stratum,the use of shallow tunnel in the formation excavation method construction project cases are very few,almost no ready-made experience to draw upon.With the complete development of the project,the construction of tunnel construction in the pebble bed is a problem that needs to be solved.On this basis,this paper niang cover several key problems in the village during the tunnel construction,surface subsidence rule of pebble stratum and its prediction method,the shallow depth excavation method the preliminary support of the reasonable measures and methods of construction,the tunnel construction safety management and so on has carried on the system research,its work embodies in the following aspects:1.Select representative sections and conduct field monitoring data analysis.The characteristics of surface subsidence stage caused by excavation of tunnels are expounded.Use of parameter back analysis method,to Peck formula fitting calculation of monitoring data,analyzes the embedded depth of tunnel longitudinal center line of H and settlement trough width I mathematical relation,put forward the suitable for settlement trough width coefficient k of this tunnel.2.Based on the theory of stochastic media,the formula of subsidence caused by excavation of multi-channel tunnel is deduced.Using the MATLAB program,the surface subsidence is predicted.In this paper,the prediction value and the actual measured value were compared and analyzed,and the adaptability of the prediction of surface subsidence of the tunnel was verified by the theory of stochastic media3.Combined with niang cover village tunnel import and export section of construction practice,using the finite element simulation method from the early stages of surface settlement and deformation of supporting structure,primary support,longitudinal horizontal displacement constraints and stress four aspects analyzes the CD method and circular excavation for core effect on the safety of tunnel construction method,and the two methods of monitoring measurement data is analyzed,it is concluded that gravel strata the reasonable method of the shallow tunnel.4.Advance under the guard of 26 cases of anchor bolt are simulated calculation,proven measures for the preliminary support of the anchor in gravel formation effect,reasonable preliminary support method and parameters are given.5.On the basis of the existing monitoring system,the paper puts forward the standard of the displacement monitoring for the tunnel of nianga village.