Method for preventing permafrost layer from feeding water to inflow in excavation pit by using waterproof film

Abstract

The invention relates to a method for preventing a permafrost layer from feeding water to inflow in an excavation pit by using a waterproof film. The method is characterized in that a slot is excavated around a planned pit; the depth of the slot is a depth being 0-100 cm below underground permafrost table; a layer of bentonite or clay with a thickness of 1-30 mm is paved at the bottom of the pit slot; the waterproof film is arranged in the excavated pit slot, and is fully arranged at the bottom of the excavated pit slot; the waterproof film reaches a ground surface along the pit wall, so as to form an L shape and refill and bump with filled soil; and the vertical part of the L-shaped waterproof film along the pit wall is 0.5-5 m far away from the edge which is close to the pit to be excavated. With the adoption of the method provided by the invention, the influence of underground water on an engineering construction process and a frozen earth foundation can be effectively avoided; the water can be effectively stopped by sufficiently considering characteristics of a frozen earth structure, underground water soil properties and characteristics of a hydrological structure, and arranging the waterproof thin film with a special structure around the pit to be excavated. Meanwhile, the water inside the excavated pit can be continuously regulated after engineering construction, so that the purpose of maintaining the stability of the frozen soil foundation for a long period can be realized.

Description

technical field [0001] The invention relates to a method for using a water-proof membrane to prevent water from the frozen layer from gushing into the excavated foundation pit during the excavation of the foundation pit of the engineering building in the cold season of the permafrost region Background technique [0002] my country has a large area of ​​high-altitude permafrost and high-latitude permafrost. In the vast permafrost area, major national projects such as Qinghai-Tibet Highway, Qinghai-Tibet Railway, Qinghai-Tibet Power Transmission Line, Northeast Harbin-Dalian Highway, and Sino-Russian Oil Pipeline have been carried out. building. During the construction of these projects, especially the construction of major transmission lines of the Qinghai-Tibet DC Interconnection Project carried out on the Qinghai-Tibet Plateau from 2010 to 2011, it was inevitable to carry out a large number of foundation pit excavations, which resulted in Some important engineering problems...

AI Technical Summary

Problems solved by technology

However, in the permafrost region, due to the existence of the permafrost water barrier, it is difficult for groundwater to pass through the permafrost layer, its water level is difficult to change greatly, and it is difficult to collect into the drainage holes, which leads to the failure of conventional methods.

Secondly, the large amount of heat generated during the solidification process of the high-pressure jet grouting method leads to the thawing of the frozen soil under the roof of the frozen soil surface, which will cause serious thermal disturbances to the frozen soil, making it difficult to play an effective role in the excavation construction of the foundation pit.

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