Numerical Simulation Of Tunnel Construction And Measurement Technology Of NATM

Since the Reform and Opening,China's economy has been growing rapidly.China's national strength has been continuously improved.More and more new technologies have been put into use.Tunnels and underground engineering have made tremendous progress and achievements.Nowadays,China has become the country with the largest number of tunnels and underground works,the longest tunnel length,the most complicated geological conditions of construction and tunnel structure,and the fastest development of construction technology.Tunnel construction safety and risk management are emphasized right now.In this paper,the LiuYang River tunnel is taken as the engineering background.Simulating the tunnel's construction process and analyzing its results through the finite difference software FLAC3 D.The paper focuses on researching the deformation of the surrounding rock around the tunnel through different excavation methods,and give suggestions to actual project.The main work and conclusion of this paper are as follows:(1)Using three different construction methods,include CRD method,benching method,and full cross-section method,simulate the tunnel construction under different surrounding rock conditions.And analyzing the displacement of surrounding rock.The results show that the CRD method can reduce the deformation of surrounding rock and surface subsidence obviously.The full cross-section method result in the largest surface subsidence and deformation of the surrounding rock.(2)The vertical displacements rock during the tunnel excavation are the largest at the upper surrounding and bottom surrounding rock,and the horizontal displacement of the surrounding rock near the side wall is the largest.(3)When using benching method for tunnel excavation,the length of the benching could affect the deformation of the surrounding rock.Because of the quick closing speed of the tunnel,the preliminary bracing provide better supporting effect.The construction of the short benching has better performance than long steps in surrounding rock displacement control.(4)During the tunnel excavation,large stress concentration will occur side of the tunnel,which can relieve the surrounding rock stress to a certain extent after the secondary lining is completed.(5)The stability of the surrounding rock of the unsymmetrial loading tunnel near the surface side is weak,and appropriate measures should be taken to reinforce the surface before construction so as to avoid collapse of the tunnel.