| To date, attention has been paid on waterproofing lining and fast construction of heavy haul railway extra-long tunnel when the tunnel is positioned at the rich-water zone, which is focused by academy and engineering. In teams of critical parameters and stability of tunnel in water-bearing stratum, theoretical analysis, numerical simulation, field test and engineering application were carried out. Consequently, the conclusions can be drawn as follows:1. In terms of heavy-haul railway in Taihangshan, we analyzed quantitatively the relationship among water pressure on lining, drainage charge, thickness of curtain grouting. In combination with numerical simulation, the function of drainage facilities is not expected well, along with reliability during operation. It is suggested that the lining with resistance of water pressure 1 MPa should be placed by the lining withstanding water pressure of 0.3 MPa, and lining resisting 0.5 MPa can be placed by 0.2 MPa. The safety factors can meet the code’s requirements. These modified parameters of lining enable reducing the construction difficulties and economic cost.2. Different strata are encountered in process of construction of Taihangshan tunnel, such as curtain grouting, surrounding rock grouting and working in water. It takes too much time to implement the schemes of curtain grouting, surrounding rock grouting that are not capable of meeting the requirements associated with construction period and engineering cost. Thus, we have to modify it. Concerning the field situation of Taihangshan tunnel, we modify and improve the working scheme in water, which not only arrive at the safety requirement, but also at excellent effectiveness of construction.3. Aiming at solve thoroughly the disastrous hazard of monolithic roadbed during operation due to draining capacity inadequacy of heave-haul railway lateral ditch, we propose two new types of structure. Namely, when good surrounding rock, drainage ditch is excavated under the lining, and supporting arch is constructed on the drainage ditch. The monolithic roadbed is built on the arch structure. When the poor rock mass with influence of ground water, piled beam-slab structure is performed to transfer loads of monolithic roadbed and train to the stable rock under the tunnel, thus reducing the influence of underground water on the monolithic roadbed.4. As for F4 fault in Taihangshan tunnel. The water is recommended to be released. The affected length ahead working face to extrusion deformation reaches 0.8 D. Due to the stiff deference between fault and its surrounding rock, the uneven deformation of lining appears in the tunnel-axis direction. The lining shall be reinforced ahead and after the boundary of fault 1.3 D to prevent shearing and tensile failures of lining that can ensure the stability of tunnel and reducing the risk during the opration.5. Inspection of on-site field at Taihangshan tunnel reveals that the main surrounding rock pressure is in vertical direction. The maximum pressure appears at the arch shoulder. The asymmetric distribution of rock pressure may be induced by geologic strata and asynchronous constructions of both laterals of tunnels. The value of surrounding rock pressure is small that will not result in the lining cracks, which is consistent with lining safety of on-site field. |
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