Experimental Study On Mechanical Properties Of Steel-SCC-Segment Three-layer Superimposed Lining Structure Interface

With the needs for economic development of different regions and the differences in population mobility,the use of water resources is uneven in various regions.The use of pressuried shield tunnel for cross-basin water diversion can effectively solve the problem of water resources allocation.For the environment and the own water delivery requirements,the pressuried shield often bear large external loads from water and soil and internal loads from water pressure.The multi-layer lining structure is often used in the project to improve the overall bearing and deformation performance of the structure.Due to the deep burial depth of the tunnel and the presence of high internal water pressure,the lining structure is subjected to complex internal and external loads,resulting in the interface being subjected to a combination of cross-section axial force and internal and external pressure.However,the research on multi-layer lining at home and abroad is not yet mature.This thesis relies on the "Steel-SCC-Segment" three-layer superimposed lining structure used in the the Pearl River Delta Water Resources Allocation Project.This structure is more complicated than the conventional double-layer lining structure,and its interface form is complex.Relying on the engineering three-layer lining structure Steel-SCC and Segment-SCC interface,through the design and development of interface tests,the three-layer lining structure bending interface performance test and the three-layer lining structure bending finite element model analysis,etc.A preliminary study on the mechanical properties and deformation characteristics of the interface for the complex lining structure.The main work of this thesis is summarized as follows:(a)Firstly,based on the form and local stress conditions of the three-layer lining structure interface of "Steel-SCC-Segment",the Steel-SCC and Segment-SCC interface test and monitoring program were designed,and then based on the overall stress characteristics of the whole lining structure interface,a three-layer lining overall bending interface performance test and monitoring program were designed;(b)For assessing the failure characteristics of the interface,interface shear stiffness,shear strength and other indicators,the interface test was carried out to analyze the interface shear bearing capacity and deformation performance of the two interfaces under shearing or compressive forces,including interface Load-Slip,steel liner Load-Strain,both sides of the interface Load-Strain analysis of concrete,etc;(c)Conduct a flexural interface performance test of the three-layer lining structure,describe the process of the lining structure under the bending moment and axial force at the same time,and analyze the overall deflection of the lining structure,the relative disengagement and slippage of the interface deformation,segment and steel lined steel bar strain,to explore the force deformation characteristics of the interface when the lining structure is fully stressed;(d)Using the relevant interface parameters obtained by the interface test,establish a flexural finite element model of the lining structure which was compared with the test to verify the reliability and applicability of the model.Then based on the verification model,the interface performance of the lining structure under internal hydraulic conditions is carried out with the finite element simulation analysis,which initially explored the effect of internal water pressure on the relative deformation of the interface.Finally,the effect of different spacing of stud for the interface performance of the lining structure is analyzed by the finite element model,which provides a reference for the design of steel lined studs.