Research On The Construction And Stability Of Bias Neighborhood Tunnel

Neighborhood Tunnel is a form of tunnel structure between separated tunnel and arch tunnel, and it has many advantages: like developing the mechanical properties of rock, reducing project costs, simplifying the construction process and increasing the overall stability of the tunnel. But limited to the linear, topography and geological conditions, the bridge often connect to the tunnel directly, which inevitably encounter problems with the slope tunnel bias skewed. So the design and construction of small spacing bias tunnel is one of the hot and difficult problems of the current civil engineering concern. This paper analysis the research status of the shallow bias neighborhood tunnel firstly, and then combined with the existing research results, based on the engineering shallow bias segment of Xiangshan tunnel on Mazhu highway, using theoretical analysis, finite element simulation and on-site monitoring data analysis methods, the key issues of the shallow bias neighborhood tunnel design and construction have been studied and discussed, the main conclusions are as follows:1. Have theoretical analysis to neighborhood tunnel rock pressure under the shallow bias condition to obtain bias neighborhood tunnel force characteristics, as well as failure modes of the tunnel.2. The process of Xiangshan tunnel excavation and blasting process is simulated. By numerical simulation we obtain the effect of the order of cave excavation and blasting vibration on the rock stress and displacement, especially on the septum rock stability, and then according to the simulation results, take appropriate measures to reinforce the dangers and weak parts and the septum rock.3. Having monitoring and measurement on Xiangshan tunnel construction site, we obtain the Xiangshan tunnel excavation of the tunnel left right hole crown settlement, convergence and the impact of the surrounding rock pressure. And we compared the on-site monitoring results with the numerical simulation results.4. Based on field monitoring and measurement data, establish gray neural prediction model by the gray theory and neural network theory to predict the displacement of the tunnel. The predicted results have comparative analyzed with on-site monitoring results, and get the conclusion that the prediction of gray neural prediction model have higher accuracy, which have a large help for tunnel construction forecast and provide references for the design and construction of bias neighborhood highway tunnel.