Study On Stress Characteristics Of Tunnel Structure Under The Dislocation Of Small-Angle Intersecting Oblique-Slip Faults

Active faults can generally be divided into strike-slip faults and dip-slip faults according to the relative movement of the two sides of the fault,but in fact,the two sides of the fault often do not slide completely along the cross-section inclination or cross-section strike,but slide in a direction that is oblique to the cross-section strike,so the translational fault is combined with normal and reverse faults to form an oblique slip fault.When the tunnel cannot avoid crossing the active fault,the specification recommends crossing the active fault at a large angle,but in practice,due to the limitation of the line direction and terrain conditions,the tunnel also crosses the active fault at a small angle.There are few studies on force characteristics and failure modes,and there is a lack of reference materials.Therefore,this paper relies on a small-angle tunnel project in southwest China that crosses an active inclinedslip fault,and comprehensively adopts research methods such as data investigation,numerical simulation and model test,to analyze the stress of a small-angle cross-slip active fault tunnel structure under the action of fault dislocation.The characteristics of the research,the main results are as follows:1.A three-dimensional load structure model of a small-angle tunnel traversing an inclined-slip active fault was established,the stress characteristics of the secondary structure under different dislocation amounts were studied,the influence range of the fault dislocation was clarified,and the maximum shear strain criterion was proposed.For the judgment criteria of the severely affected area and the general affected area,the vertical fortification zoning of the structure under different staggered momentum is carried out;2.Developed a multi-angle model test box for tunnels traversing inclined-slip active faults,and carried out research on the stress characteristics of tunnels with different structural forms and angles that crossed inclined-slip active faults,and obtained the failure modes of segmental tunnel structures under fault dislocation characteristics,and comparatively analyzed the influence of different inverted arch structures on the stress of the tunnel structure;3.The contact surface element is introduced to simulate the deformation joints of the segmental tunnel structure.The deformation law and force characteristics of the secondary lining under different dislocations are studied,and the segment lengths of 6,9,and 12 m are analyzed.Influence of stiffness of different deformation joints on segmental structures,based on the "safety factor" in the "Code for Design of Railway Tunnels",a structural safety evaluation standard is proposed and the evaluation criteria for segmental structures under different dislocation momentums of small-angle intersecting oblique-slip faults are proposed.Security was zoned evaluation.The above research results will not only apply to the design and construction of this project,but also provide a reference for the design and construction of other similar tunnel projects in the future.