Water stop method for upper-soft and lower-hard water-rich stratum foundation pit engineering retaining structure

Abstract

The invention discloses a water stop method for an upper-soft and lower-hard water-rich stratum foundation pit engineering retaining structure. The method includes the steps that firstly, a cast-in-situ bored pile is constructed; secondly, on the outer side of the cast-in-situ bored pile, a high-pressure jet grouting pile or a three-shaft stirring pile is constructed; thirdly, a hole is drilled in the center of the high-pressure jet grouting pile or the three-shaft stirring pile, and high-pressure jet grouting or sleeve valve pipe grouting is performed; fourthly, deep hole curtain grouting is performed; fifthly, a first-layer small guiding pit is excavated; sixthly, preliminary-stage supporting is performed on an upright excavation face of the first-layer small guiding pit; seventhly, core soil is reserved during excavation of a first-layer foundation pit; eighthly, a first-layer transverse steel purlin is arranged, and a steel cross brace is erected; and ninthly, when the pre-designed strength of the retaining structure is achieved and the monitored and measured result is accurate, next circulation is performed, and the fourth step, the fifth step, the sixth step, the seventh step and the eighth step are repeated till construction ends. The method is good in main water stop effect and good in flexibility. The technology is simple, the construction risk is small, influences on the environment are small, and adaptability to a complicated stratum is high.

Description

technical field [0001] The invention relates to a water-stopping method that can be used in foundation pit engineering, especially at weak positions such as upper soft soil layers and soil-rock interfaces in upper soft and lower hard water-rich formations. Background technique [0002] With the development and utilization of underground space, complex foundation pit engineering has become a controlling project for the construction of some large buildings, rail transit, municipal, railway, highway and other projects. The geological conditions in quite a few areas in my country are complex, especially the leakage of foundation pits under the condition of upper soft and lower hard water-rich strata, which brings great difficulties and risks to underground engineering construction. [0003] In the existing patents, there is no water-stopping method for the upper soft and lower hard formations, especially the water-stopping at the soft-hard interface of the upper soft and lower h...

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Problems solved by technology

[0004] In the prior art, high-pressure jet grouting piles or three-axis stirring piles are generally used to form a water-stop curtain for weak water-rich strata. However, in the case of high water volume and pressure, the soft-hard interface often becomes the groundwater confluence layer. The medium at the place is easy to be washed away by water and cannot form a solidified pile, and the water-stopping effect is very unsatisfactory

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