Tunnel lining plays an important role in the support of tunnel engineering. It is a permanent support structure built along the periphery of the tunnel body in order to prevent deformation or collapse of the surrounding rock. In actual construction, the quality control of the following links needs to be done. For details, please go to look down.
01. Lining construction
(1) The secondary lining must be carried out when the deformation of the surrounding rock and the initial support is basically stable, and the displacement convergence speed is obviously slowing down, and the various displacements must reach 80% to 90% of the estimated total displacement.
(2) Before the construction of the lining, the waist line must be measured to control the deviation of the invert and foundation pouring, and the lining section base surface and vault elevation should be detected. The thickness error of the tunnel lining meets the design requirements to ensure the clearance height in the tunnel.
(3) The thickness and compactness of the lining must be checked after the construction of the lining, and the electrical signal of the corresponding frequency is generated by the transmitter according to the command of the control unit for detection.
(4) The construction site of the lining must be continuously measured, and continuously collected along the measuring line during the inspection, paying attention to stable movement and uniform speed.
02. Construction of lining structure
(1) Strictly control the mixing ratio of concrete, check the quality of raw materials before mixing, and do not change at will after test verification. Add accelerator according to the construction environment temperature.
(2) In order to ensure the quality of concrete, it must be sprayed with the mixing and continuous spraying; check whether the mechanical equipment is operating normally before construction.
(3) The steel mesh used for lining must be spot welded into blocks at the intersection, and the anchor rods must be laid after completion to ensure that the mesh is close to the initial spray surface. After the construction is completed, the thickness of the concrete protective layer and the connection performance of the steel must be tested.
03. Formwork construction
(1) Ensure that the formwork engineering support is firm and stable, and check whether there is excessive deformation and subsidence; the rigidity of the formwork support at the large variable section must be checked, and it must be correctly lofted before installation.
(2) Ensure that the surface of the formwork is cleaned, and the mold release agent is applied to ensure the quality of the concrete molding; during the construction, pay attention to the flatness and tightness of the joints, and there is no hidden danger of misalignment.
(3) The error of each part of the control structure meets the requirements, the elevation of the vault does not exceed 10mm, the error of the center line does not exceed 10mm, and the error of clearance does not exceed 10mm.
04. Crack treatment
(1) Fine cracks can be painted with epoxy resin slurry after cleaning, and then the surface of the concrete can be treated with scraping material and toning material to achieve a beautiful effect.
(2) For penetrating cracks, a V-shaped groove must be cut along the direction of the crack, and drill holes shall be drilled across the cracks in the groove. After removing the debris, the epoxy cement mortar shall be used for anchoring, and the same strength grade cement shall be used to smooth it on it.
(3) Dense cracks must be additionally waterproofed and reinforced. Cement mortar should be injected into the cracks to ensure full grouting; anchor pads should be installed 1 day after grouting, and then filled with epoxy mortar.