Research of seepage characteristics and penetration resistance during installation of bucket foundations in sand

The penetration of the bucket foundation is a vital construction procedure. Seepage field is generated in the soil under the suction pressure during the penetration. The seepage has an influence on the friction along the skirt wall and on the resistance of the skirt tip, which leads to the difficulty in predicting penetration resistance. In order to solve this problem, firstly, the methods of experiment and numerical simulation were applied to analyze the seepage characteristics of the bucket foundation during the penetration; moreover the distribution of the excess pore water pressure along the bulkhead and skirt tip was revealed. Thereafter, the analytical results were applied to derive the penetration resistance, and the derived theoretical formulae were verified. The results show that during the penetration of the bucket foundation, the excess pore water pressure of the soil changes linearly along the depth of the skirt, but becomes nonlinearly near the skirt tip. The effect of seepage flow on the penetration resistance is different for different penetration depths; the reduced resistance caused by seepage accounts is for a greater proportion of the penetration resistance with increasing penetration depth. The suction pressure of the test model and practical engineering calculated by the theoretical formulae are in good agreement with the measured values.