Study On The Optimization Of Hinge-flexible Layer Ductile Support Structure And Its Main Parameters Under Creep Slip Fault

With the increase of state support for the west,the terrain of the western region is changeable,the altitude is undulating,and the construction of a large number of traffic arteries requires tunnel structure to participate in it,and due to topographical reasons,the tunnel structure will inevitably be adjacent to the active fault fracture zone area or even directly cross,and the active fault misalignment is very easy to cause accidents such as tunnel lining dislocation cracking and even collapse,which seriously threatens the safety of tunnel construction and operation.Taking the Shantou Bay Tunnel,a key project of the Shantou Railway,as the prototype,this thesis applies the newly designed tunnel fault-resistant support structure to the lining articulation design,analyzes the structural mechanical response law of cross-active fault tunnel,explores the influence of the main parameters of the new supporting structure system on the tunnel anti-faulting performance by numerical simulation method,obtains the optimal parameter combination,and carries out relevant model tests to verify the numerical simulation calculation results.The main research results achieved are as follows:(1)A kind of articulated and flexible layer toughness anti-fracture support structure is independently designed,which can play the role of energy absorption buffer when the fault is creep-slip and mismove,reduce the interaction between tunnel lining segments,reduce the influence range of fault misalignment on the lining structure.When the tunnel structure is sheared and bent,the steel plate and rubber plate in the new support structure are squeezed to cause a slight corner displacement of the lining segment,which reduces the internal force and force deformation degree of the tunnel lining structure and avoids the occurrence of integral damage.(2)The mechanical response characteristics of tunnel structure under different fault inclination angle,misalignment distance and width conditions were compared and analyzed.The results show that the larger the inclination angle of the reverse fault,the smaller the maximum principal stress peak at the vault and inverted arch,while the maximum principal stress peak at the arch waist decreases with the increase of the inclination angle of the fault.When the fault staggering distance reaches 10 cm,the peak shear stress of the lining occurs at the arch position of the tunnel and the fault intersection,which is 0.27 MPa.The maximum principal strain at the arch waist is greater than that of the circumferential section at different positions when the fault is staggered,and the fault width of 10 m is 1.16 and 1.43 times under the condition of width 15 m and 20 m,respectively,so it is necessary to carry out key fortification of the tunnel arch.(3)By comprehensively comparing the effects of segment length,structural width and material strength on the mechanical response of tunnel structure in the new supporting structure system,it is concluded that reducing segment length,increasing structural width and appropriately reducing the strength of structural materials can effectively reduce the internal force and deformation degree of tunnel structure.The optimal parameter combination is: the segment length is 6 m,the structural width is0.75 m,and the strength ratio of the structural material is 1/150,and the maximum principal stress,shear stress,maximum principal strain and vertical displacement peak of the lining are the largest decreases,reaching 78.4%,75%,78.1% and 33.3%,respectively,and the anti-fault effect is the best.(4)The model test of the anti-fault performance of the articulated-flexible layer toughness support structure was carried out,and the influence of the change of segment length on the anti-fault performance of the tunnel was revealed,and the numerical simulation results were compared and verified.The test results show that the contact pressure and strain of different parts of the lining ring section show a decreasing trend with the decrease of segment length within a certain range.Compared with the traditional tunnel,the affected range of the new support system tunnel can be reduced by up to 50%,and the contact pressure and longitudinal and circumferential strain at different positions of the tunnel can be reduced by different amplitudes.When the segment length was 4 cm,the decrease amplitude was the largest,58.3%,81.6% and 41.5%,respectively,and the anti-fault effect was the best.