Abstract
Down-hole dynamic compaction is one of the important engineering technology to solve the problems of insufficient bearing capacity and uneven settlement after construction for deep slag miscellaneous fill foundation. Based on the deep slag miscellaneous fill foundation treatment project of an expressway, several groups of field tests were carried out, such as different pile forming processes and different pile spacing. Through the super heavy dynamic penetration test and foundation bearing capacity test, the reinforcement effect of down-hole dynamic compaction on the soil between piles of miscellaneous fill foundation is studied. The results show that the down-hole dynamic compaction has a significant reinforcement effect on the deep slag miscellaneous fill. After treatment, the compactness of the undisturbed slag miscellaneous fill changes from loose to medium dense or dense, and the soil compression modulus increases significantly. In addition, according to the compaction effect of soil between piles, the improvement effect of punching pile with small pile diameter on the bearing and deformation capacity of foundation is better than that of rotary digging pile with large diameter. Finally, deep dynamic compaction in the hole will have a certain disturbance on the shallow soil. In engineering applications, after the completion of the pile, the surface soil should be tamped to ensure the overall treatment effect of the foundation.