Study On Surrounding Rock Stress And Supporting Of Small Cross-section Tunnel For Pipeline Crossing

West to east gas pipeline project in China is to turn the advantages of western Nat gas resources into the major projects of western economic advantages.It can also promote the energy structure adjustment and the economic benefits increase of several provinces,cities along this line.Oil and gas pipelines are too long and they need to cross a lot of mountains and rivers,so we must build a large number of oil and gas pipeline tunnels which cross the mountains and rivers.The section of oil and gas pipeline tunnel is small,and the stress and deformation characteristics of supporting in these small cross-section tunnels are different from those in general.So the research on the dimension optimization and support form of this small cross-section tunnel has become an important subject in the field of tunnel engineering.We use load structure method and finite element method to research on the internal forces of the structure,the deformation of surrounding rock and the mechanical rules of supporting during the tunnel construction based on Shimen Cave Tunnel.The main contents and conclusions are as follows.(1)We research on the basic theory of studying tunnel by load structure method and finite element method.It can lay the theoretical basis for specific calculation of the tunnel in future.(2)We use Platts method and empirical method to calculate the supporting deformation and its internal forces of Shimen Cave Tunnel.We compare these calculation results and find out the law between them.(3)We use finite element method to calculate the supporting deformation and its internal forces of Shimen Cave Tunnel.The theoretical basis of finite element modeling,basic modeling parameters,modeling process,loading calculation and result analysis are described in detail.We compare these calculation results with the results of load structure method and we will know that finite element method has accuracy in the calculation of the tunnel.(4)Based on finite element method,we calculate the supporting deformation and its internal forces under different parameters of tunnel supporting and we find out some conclusions.These different parameters include the number of bolt,the diameter of bolt,the length of bolt,the thickness of the lining and the grade of concrete.The change of bolt parameters has great influence on the internal force of tunnel supporting and the changes of lining parameters mainly affect the deformation of the structure.The internal force of the tunnel can be controlled by increasing the number of the bolts,increasing the diameter of the bolts and increasing the length of the bolts.The deformation can be effectively controlled by increasing the thickness of the lining and increasing the grade of the concrete.Through the research in this paper,we get the basic rules about the internal force and deformation of tunnel supporting and we understand the impact of various factors on the tunnel.This study provides a theoretical reference for the parameters selection of the actual tunnel supporting.