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Permafrost tunnel supporting method of railway

A technology for frozen soil and tunnels, which is applied in tunnels, tunnel linings, earthwork drilling and mining, etc., and can solve problems such as unsuccessful tests and the influence of shotcrete support construction technology

Inactive Publication Date: 2010-01-06
CHINA RAILWAY FIRST SURVEY & DESIGN INST GRP
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AI Technical Summary

Problems solved by technology

As a mature construction support, wet shotcrete has been widely used in the construction of ordinary mountain tunnels, but the plateau alpine conditions will have a great impact on the construction technology of shotcrete support, and in the Dabanshan highway tunnel, Tests of wet shotcrete as construction support for tunnels in frozen soil have not been successful

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  • Permafrost tunnel supporting method of railway
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  • Permafrost tunnel supporting method of railway

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Experimental program
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Embodiment Construction

[0015] Reasonable dosage of additives such as antifreeze and early strength of wet shotcrete:

[0016] The key problem of adopting shotcrete support in plateau alpine permafrost tunnel engineering is that the strength develops slowly at low temperature. In order to improve its early strength, the emphasis is on the type and dosage of admixtures. The test content mainly includes the selection test of concrete admixtures such as accelerator, early strength agent and antifreeze agent, the influence of admixtures on the performance of shotcrete, and the compatibility test of each admixture. In order to improve the bonding strength between shotcrete and sprayed surface and reduce rebound, research on shotcrete with polypropylene fiber (referred to as PP fiber) was carried out.

[0017] Accelerator:

[0018] Accelerator refers to an admixture that can make concrete set quickly after being mixed. The main purpose of using the accelerator is to accelerate the hardening of the shotcr...

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Abstract

The invention relates to a permafrost tunnel supporting method of the Qinghai-Tibet railway, which ensures the construction safety of a permafrost tunnel and the successful construction of the Qinghai-Tibet railway and validates that concrete wet-spraying support is feasible in high plateau permafrost tunnel construction and obtains great breakthrough by adopting a concrete spraying construction technology through improving the construction technology, the mixing proportion, the reasonable temperature of a spraying technology system, the reasonable mixing amount of an antifreezer, an early strength admixture, and other additive agents, the bonding strength of a rock surface, and the like. The permafrost tunnel supporting method of the Qinghai-Tibet railway comprises the following operation steps: mixing 1.8kg / m<3> of polypropylene fiber in sprayed concrete during concrete spraying construction on a frozen rock, wherein the mixing amount of the antifreezer is 1.8 percent; and heating a liquid accelerator within the mixing amount range of 3-5 percent so that the cement paste keeps the temperature of 10 DEG C, wherein the ratio of cement to skeletal material is 1:3.4, the use amount of the cement is between 470kg / m<3> and 500kg / m<3>, the sand coarse aggregate ratio of the sprayed concrete is 60 percent, and the cement water ratio of the sprayed concrete is 0.47.

Description

1. Technical field: [0001] The invention relates to a construction support method, in particular to a permafrost tunnel support method of the Qinghai-Tibet Railway. 2. Background technology: [0002] The Kunlun Mountain Tunnel of the Qinghai-Tibet Railway is located in the plateau alpine permafrost region. The Qinghai-Tibet Plateau is high in altitude and has a large temperature difference between day and night. Some areas are in a frozen state all year round, and the freeze-thaw changes are frequent, and the melting of permafrost is aggravated due to tunnel construction, and it is still blank to use wet shotcrete support for plateau permafrost tunnels at home and abroad. . It is also the first time in the world to build a railway tunnel in such a high-altitude, high-cold, permafrost region. The construction methods and construction techniques of tunnels are quite different from those in low-altitude areas. As a mature construction support, wet shotcrete has been widely u...

Claims

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Application Information

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IPC IPC(8): E21D11/10C04B28/00C04B14/06C04B16/06
Inventor 黄双林罗朝廷刘小刚伍晓军杨国柱刘赪李国良
Owner CHINA RAILWAY FIRST SURVEY & DESIGN INST GRP
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