Research on the technology and bearing characteristics of drained cement-soil mixing piles

Cement-soil mixing piles are commonly used soft soil foundation treatment technologies in coastal areas owing to their low construction-induced disturbances, cost-effectiveness, and high performance. To further enhance the bearing performance of cement-soil mixing piles in the reinforcement of deep soft foundations, the composite drainage cement-soil mixing pile technology is proposed. This technology incorporates prefabricated vertical drains on the side of the cement-soil pile, followed by vacuum drainage consolidation to improve the quality of the cement-soil mixing pile and the bearing capacity of the composite foundation. To further examine the quality and bearing capacity of the pile system, model testing and numerical simulations were carried out. The on-site working conditions with vacuum durations of 3, 7, 14, and 28 days demonstrated that the ultimate bearing capacity of the piles increased by 2.38%, 2.95%, 4.59%, and 6.72%, respectively. The influence range of vacuuming for 28 days on the drainage and consolidation of soil surrounding the pile was 2.5 times the pile diameter. The composite drainage cement-soil mixing pile not only enhanced pile integrity but also significantly increased the strength of the surrounding soil, thereby significantly improving the effect of foundation reinforcement.