Construction method of rigid primary support of mould-building concrete of plateau permafrost tunnel

Abstract

The invention discloses a construction method of a rigid primary support of mould-building concrete of a plateau permafrost tunnel. The method comprises the following steps: 1. measuring and paying off; 2. tunnel excavation and construction: excavating by utilizing a full face excavation method; 3. construction of the rigid primary support of the mould-building concrete: erecting a grille steel frame, applying an anchor rod, hanging a reinforced mesh and pouring concrete with an initial lining trolley, namely constructing the primary support of the tunnel by utilizing a bolt-mesh-shotcreting-grouting combined support method; 4. laying of a waterproof and thermal insulation layer: laying the waterproof and thermal insulation layer on the completely constructed rigid primary support of the mould-building concrete; and 5. secondary lining construction: carrying out secondary lining construction on the laid waterproof and thermal insulation layer. The construction method has the advantages of rational design, low cost, high engineering quality and fast construction speed, is convenient in construction, effectively ensures the construction safety and quality, and simultaneously ensuresthat the completely constructed plateau permafrost tunnel has excellent water resistance and drainage functions, excellent thermal insulation function, long service life, low maintenance cost and lowlater-stage rework cost.

Description

technical field [0001] The invention belongs to the technical field of plateau frozen soil tunnel construction, and in particular relates to a construction method for molded concrete rigid initial support of plateau frozen soil tunnels. Background technique [0002] The Fenghuo Tunnel is located in the uninhabited area of ​​Hoh Xil on the Qinghai-Tibet Plateau. The area is extremely cold, low-pressure and hypoxic, and the natural environment is extremely harsh. The track surface of the constructed tunnel is 4,905 meters above sea level, which is currently the highest tunnel in the world. At the same time, the extreme minimum temperature in this area is -41°C, the annual average temperature is -6.11°C, and the coldest monthly average temperature is -17.8°C; the local average air pressure is about 70% of the average air pressure in the mainland; It is 159.71kPa (the oxygen content in the mainland is about 299.3kPa). Since the upper limit of the permafrost in the area is 1.2-...

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Problems solved by technology

[0003] Nowadays, there are few experiences that can be used for reference in the construction of plateau permafrost tunnels. At the same time, due to the large temperature difference between the sprayed surfaces of permafrost and the high rebound rate of shotcrete, when using the step method for excavation and mold shotcrete construction, not only the construction process There are many, and it is greatly disturbed by external environmental factors, coupled with plateau factors, which make the artificial efficiency low and the construction speed slow, which will easily cause permafrost melting, dripping, subsidence and collapse, and the safety and quality of construction cannot be guaranteed. Therefore, during the construction process making tunnel construction difficult

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