Back Analysis Of Support Force Baced On 3D Laser Scannig Holographic Deformantion Monitoring

The construction of domestic highway tunnels generally implements the concept of the New Austrian Method,and monitoring and measurement,as one of the cores of the New Austrian Method,plays an important role in tunnel construction.With the promotion of 3D laser technology in tunnel monitoring,more and more tunnel practitioners have realized the obvious advantages of 3D laser technology over traditional monitoring and measurement technology.Displacement back analysis is based on the displacement data of the structure.By considering the structure as an internal force sensor,the mechanical state of the structure is inversely analyzed by displacement loading.This method not only opens up a new way for the force analysis of the structure,but also avoids the many defects of traditional monitoring method that utilize insturments to monitor internal force of support structure.In this paper,the holographic deformation of the support structure obtained by 3D laser is taken as the introduction point,and the displacement reverse analysis of the mechanical behavior of the primary support is carried out by referring to relevant literature,theoretical derivation,material test,on-site monitoring and numerical simulation,and the following results are obtained:(1)Given the calculation condition of the thin-walled ring,the correctness of the numerical solution is proved by calculating the theoretical solution and numerical solution of the working condition.Then,the thin-walled ring is subjected to displacement loading,and the force back analysis of the thin-walled ring is carried out,and the displacement loading calculation is compared.The results and the numerical calculation results of the positive analysis verify the corresponding relationship between the structural deformation and the force.(2)In this paper,relying on the tunnel test section project,holographic deformation monitoring of primary support,the monitoring of radial support resistance limiting damper deformation,inner primary support structure arch foot settlement monitoring and internal force monitoring are carried out.By monitoring the deformation of the radial support resistance limiting damper and combining with the internal force monitoring data,the stress state of the inner support structure is analyzed.Combined with the holographic deformation monitoring data and the arch foot settlement data,the deformation mode and force mode of the supporting structure are consistent with the deformation pressure characteristics,so it is reasonable to use the displacement loading method to carry out the displacement back-analysis of the supporting structure.(3)According to the characteristics of the large deformation support structure,the radial resistance limiter is placed on the surrounding rock side of the primary support of the inner layer.The stress-deformation curve of the radial support resistance limiting damper obtained by the test and the deformation monitoring data of the radial support resistance limiting damper are obtained.The load distribution outside the support,based on which the relevant material parameters are inverted.The material parameters obtained by inversion are substituted for positive analysis,and the holographic deformation data obtained by 3D laser scanning are compared.The displacement data of all nodes is obtained by fitting the displacement and deformation data of the supporting structure,and the displacement loading is performed based on the displacement data of all the nodes to obtain the internal force data of the supporting structure.Compared with the internal force monitoring data,the overall error is small,and the displacement back analysis method is explained.