Determining method for design parameters of deep-layer horizontal waterproof curtain of foundation pit of strongly permeable stratum

Abstract

The invention discloses a determining method for design parameters of a deep-layer horizontal waterproof curtain of a foundation pit of a strongly permeable stratum. The determining method comprises the following steps: establishing a deep-layer horizontal waterproof curtain mechanical analysis model; separately calculating to obtain critical depths under four failure forms such as 'pull crack failure', 'compression shear failure', 'contact failure' and 'rigidity failure' of the deep-layer horizontal waterproof curtain; drawing a curvilinear relationship between the critical depth hcr and thethickness h0 of the deep-layer horizontal waterproof curtain of the foundation pit of the strongly permeable stratum, further comparing the critical depths of the deep-layer horizontal waterproof curtain under the four different 'failure forms', and selecting the maximum values of the four critical depths as a critical depth design value of the deep-layer horizontal waterproof curtain; and drawinga relation curve between the critical depth of the deep-layer horizontal waterproof curtain under different safety factors and the thickness of the horizontal waterproof curtain so as to obtain the optimal deep-layer horizontal waterproof curtain design parameters which meet requirements of safety factors. The obtained designed parameters are reasonable and reliable, and construction safety of the foundation pit of the strongly permeable stratum is ensured.

Description

technical field [0001] The invention relates to the field of underground engineering, in particular to a method for determining design parameters of a deep horizontal water-stop curtain for foundation pits in highly permeable strata. Background technique [0002] In recent years, with the vigorous development of urban underground space construction in my country, the construction of foundation pit projects has become more and more extensive, showing the characteristics of "large number, large scale, and deep depth". The groundwater levels in coastal (river) cities such as Shanghai, Guangzhou, Tianjin, Fuzhou, and Wuhan in China are generally high. During the excavation of deep foundation pits, precipitation is first required. However, the aquifer thickness of deep foundation pits in coastal cities is very large, and the relatively impermeable layer is buried relatively deep. If the traditional vertical water-stop curtain scheme with falling bottom is used for partition, the ...

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Problems solved by technology

[0003] After searching the existing technical literature, it is found that the reasonable range of the deep horizontal water-stop curtain has not been determined, and there are few related studies on the determination of the overall reinforcement depth and thickness. If the traditional earth pressure balance method and seepage force balance method are adopted The pit inrush calculation method ignores the anti-inrush effects of parameters such as the shear strength and stiffness of the deep horizontal water-stop curtain seepage barrier, so the results obtained are quite different from the field conditions. The mechanical performance parameters (shear strength, stiffness and permeability coefficient) of the water curtain have been greatly improved. Therefore, when analyzing the foundation pit inrush problem under the deep horizontal water-stop curtain, the influence of these mechanical parameters on it should be considered.

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