Tunnel Profile Deformation Monitoring Studying Based On Terrestrial Laser Scanning Technology

With society development,the development and utilization of ground space in large cities tends to be saturated.While the construction technology of shield tunnels continues to improve,information construction has become an inevitable trend in underground engineering,and realtime deformation monitoring of the project will also play a more important role.Compared with traditional contact monitoring methods and total station monitoring methods,3D laser scanning technology has high monitoring efficiency,low requirements for light,convenient stationing,no need to arrange measuring points,wide data collection,and acquisition of the overall 3D model of the cross section.This article focuses on the advantages and feasibility of 3D laser scanning for tunnel cross-section monitoring through 3D laser scanning technology on-site monitoring and numerical simulation analysis of the tunnel cross-section,and the construction load is an important factor influencing the deformation of the tunnel section.Therefore,the influence of the three factors of grouting pressure,jack thrust and earth silo pressure on the deformation of the tunnel section is simulated and analyzed.By comparing and analyzing the scanning results with the numerical simulation results,the deformation rule of the segment lining is obtained,the safety and stability of the further tunnel construction are predicted,and the information guidance and suggestion for the shield excavation process are provided.The main research works are as follows:(1)The article summarizes and analyze the data collection and processing theory combining the cloud coordinate calculation theory,ICP algorithm,RANSAC algorithm,and least squares theory.Based on this,the scanning scheme and post-processing method of tube slice deformation are formulated.It also introduces the theory of shield machine type selection,segment design and construction load calculation.(2)The article researches on the influence of different construction loads on the tube slice deformation.Excavation model of shield tunnel is obtained through engineering geological survey and numerical simulation.The finite element software Midas GTS NX was used to analyze the deformation law of tube slice on the tunnel wall during the process of shield excavation,and three influencing factors of jack thrust,grouting pressure and earth bunker pressure were selected to study the deformation law of shield tube slice under different construction load conditions.It is found that within a reasonable range,the amount of deformation of the segment is proportional to the thrust of the jack,inversely proportional to the grouting pressure,and not related to the size of the earth bunker pressure.(3)The article researches on the influence of tube slice deformation in different construction Stages.Using three-dimensional laser scanning technology,through fitting the monitoring cloud data with curved surface,selecting 25 sections,the tube slice deformation law during the three construction stages of shield excavation,shield stoppage and tunnel opening were comparative analyzed.It is concluded that the basic deformation form of the lining segment is the sinking of the vault,the floating of the arch bottom,and the expansion of the arch waist on both sides.The deformation of the segment gradually stabilizes and meets the limit requirements of the segment deformation.And the vault is the most important monitoring point for the safety and stability of the tunnel.It also provides information guidance and optimization for on-site construction such as controlling the thrust of the jack during shield excavation,ensuring the uniformity of the grouting pressure,and maintaining the balance of the pressure of the soil silo on the excavation surface.(4)3D laser scanning provides information guidance.By comparing and analyzing the monitoring data with the numerical simulation data,it is possible to predict the safety and stability of further tunnel construction.It also provides information guidance and optimization for on-site construction such as controlling the thrust of the jack during shield excavation,ensuring the uniformity of the grouting pressure,and maintaining the balance of the pressure of the soil silo on the excavation surface.