A method of calculating the bearing capacity of sand pile composite foundations in a mucky soil layer considering consolidation

Yongtao Zhang,Enlong Liu,Benliang Yang,Dejie Li,Peishuai Chen,Huiwu Luo,Yuqing Liu

doi:10.1038/s41598-021-95678-0

Abstract

In engineering practice, the measured bearing capacity of a sand pile composite foundation in a mucky soil layer is much larger than the design value. Based on the sand pile construction and the load application process, a method of calculating the bearing capacity of the foundation based on the effective stress was proposed. Cavity diameter expansion in sand pile construction was simplified into a planar problem, and the cavity expansion theory was used to establish the expression of the rate of displacement and the horizontal stress increase. Based on the e–p curve and the calculation of the degree of consolidation, the relationships between the horizontal and vertical effective stress and the void ratio were obtained. According to the close relationship between the bearing capacity of the foundation in a mucky soil layer and the water content, an expression describing the relationships between the bearing capacity of the foundation, effective stress, void ratio, and water content was established. For the temporary engineering foundation treatment project, which needs a high bearing capacity but allows large foundation deformation, the design of sand pile composite foundations uses these relationships to take the consolidation effect of mucky soil into consideration, thereby reducing the replacement rate and lowering the construction cost.

Highlights

In engineering practice, the measured bearing capacity of a sand pile composite foundation in a mucky soil layer is much larger than the design value
The bearing capacity of the foundation is related to the cohesion c, the internal friction angle φ, and the uniform load q acting on both sides of the foundation[14], but the change of the cohesion and the internal friction angle caused by the increase of effective stress remains to be verified
The reasons why the bearing capacity of the sand pile composite foundation is much larger than the design value was explored

Summary

Introduction

The measured bearing capacity of a sand pile composite foundation in a mucky soil layer is much larger than the design value. The construction of sand compaction piles leads to an increase in the bearing capacity of the soil foundation between the piles. This theory was used to calculate the increase of the bearing capacity of the foundation in the mucky soil layer caused by sand pile construction.

Results

Conclusion