Parametric Study On Pipe Support Of Shallow-buried Area Biased Double-arch Tunnel

The pipe shed method is a kind of advanced pre-supporting method for shallow-buried underground excavation of underground structure engineering.Its function is to pre-drill and install in the initial support and secondary lining arch ring arc after underground tunnel excavation.The thick-walled steel pipe with large moment of inertia plays a temporary advance support role to prevent the collapse of the tunnel arch soil layer and reduce the subsidence of the surface soil layer,ensuring the safe operation of the tunnel excavation process and subsequent support work.Pipe shed construction has been widely used in tunnel construction in recent years,especially for shallow buried bias and tunnels with soft soil.This paper analyzes the design and construction of the pipe shed method,combines theoretical analysis and numerical simulation to discuss the parameters of the pipe shed,and then uses the monitoring and measurement of the arch settlement and surface settlement data in the actual project to compare it with numerical simulation.The results were compared and analyzed to complete the following work:1.The characteristics and stress characteristics of shallow-buried double-arch tunnels are summarized.The causes of collapse and the treatment measures in the construction process of weak and loose rock formations are analyzed.The types of pre-supported pipe sheds and the force range of pipe sheds are reviewed.Theory,analysis of surrounding rock pressure theory of shallow buried tunnel and existing surrounding rock pressure theory,2.Based on the existing theory of surrounding rock pressure and the surrounding rock pressure theory of shallow buried tunnel,the Winkler elastic foundation model and the two-parameter Pasternak elastic foundation model of two mechanical models are established,and the deflection of the pipe shed is established when two foundation models are established.Equations,using equations to analyze the bending moment,shear force and deflection of the pipe shed.3.Combined with the actual concrete project Wenzhou Yayu shallow-buried double-arch tunnel,using the Midas GTS NX software numerical simulation to discuss the displacement deformation of the shallow buried tunnel under the support of the pipe shed,the tunnel shed under different bias angles The force analysis,the maximum displacement deformation position of the same section arched pipe shed,the differentexcavation sequence of the double arch tunnel,the force analysis of the pipe shed,the different arrangement of the pipe shed layer,the force analysis of the pipe shed,the pipe shed under different grouting materials The force analysis,the horizontal insertion angle of the pipe shed,the force analysis of the tunnel,the circumferential spacing of the pipe shed and the diameter selection of the steel pipe are used to analyze the force of the tunnel,and the actual data comparison and discussion of the field monitoring and measurement are used to ensure the finite element numerical simulation results and the actual monitoring results are consistent.