Abstract: Taking the narrow foundation pit construction in deep soft soil area as the background, in view of the fact that the strength of soil above the wall bottom and the influence of structural width cannot be considered in the current application of Prandtl calculation formula for checking the anti-uplift stability coefficient, a modified calculation method of anti-uplift stability coefficient is derived according to the idea of limit equilibrium. This method divides the types of narrow foundation pit with different failure slip surfaces according to the size of narrow foundation pit and the soil properties of formation, and then deduces the calculation formula of anti-uplift stability coefficient considering the shear strength of soil in the pit. Then the strength reduction method is used to compare and analyze the factors influencing anti-uplift stability with the method in this paper, and the rationality of the slip surface assumption and the practicability of the calculation method in this paper are clarified. The results show that this method can better reflect the beneficial effect of the narrowed width of the narrow foundation pit on the stability against uplift, and can provide guidance for the optimal design of the narrow foundation pit, which also needs further research and verification.
Keywords: narrow foundation pit; anti-uplift stability; influence of width; Prandtl formula; strength reduction method