A construction method for bottom-building and freezing of underground excavation subway stations in sand and pebble strata

Abstract

The invention discloses a base constructing and freezing construction method for underground excavation of a subway station in a sandy cobble stratum. The sandy cobble stratum freezing construction method comprises the following steps that (1), underground excavation of a station vertical shaft, a horizontal channel and a first layer of the station for a subway is constructed; (2), freezing pipes are constructed according to the design requirement, the freezing pipes comprise the overall freezing pipes and the local freezing pipes, and the overall freezing pipes and the local freezing pipes form a freezing curtain of waterproof space; (3), after the freezing pipes are constructed, an active freezing stage is entered, and after the freezing pipes are constructed, a base plate of the second basement of the subway is poured; (4), when a closure of a freezing wall reaches the designed thickness, a vertical shaft and a horizontal channel of the third basement are constructed, the freezing pipes of the base plate are cut, base plates of the vertical shaft and the horizontal channel are poured of the third basement, and the rest freezing pipes of the curtain are cut; and (5), the freezing pipes of a main base plate in the station are cut, after soil masses of the third basement are all excavated, and when the overall base plates are poured to reach the designed strength, the rest freezing pipes are cut, and grouting and backfilling are conducted in the freezing pipes to strengthen the anti-overturning capacity of the base plates.

Description

technical field [0001] The invention relates to the technical field of frozen water stop support, in particular to a construction method for bottom-making and freezing of underground excavation subway stations in sand and pebble strata. Background technique [0002] With the continuous development of my country's social economy, the urban population is growing rapidly, especially in first-tier cities such as Beijing, Shanghai, Guangzhou, and Shenzhen, where the per capita living area is rapidly declining and urban traffic congestion is serious. In order to solve these problems, the government timely adjusts the city's The development mode has changed from the previous plane development to the three-dimensional space development, that is, in the limited urban plane space, the urban underground space is vigorously developed and utilized. Taking Beijing as an example, as of 2016, Beijing has opened 18 subway lines, with a total operating mileage of 527 kilometers. According to t...

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Problems solved by technology

[0003] The freezing method is to use artificial refrigeration technology to freeze the water-bearing strata into a closed and impermeable curtain, that is, the frozen wall, which is used to resist ground pressure, water pressure, and isolate groundwater, so that the construction surface can be raised and constructed under its protection. The most effective ground water sealing method is widely used in the construction of coal mine shafts, and has gradually been applied to the construction of subway communication passages in recent years, but the scope of application is small, and there are few reports on urban underground space projects that use freezing water sealing in large areas

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