Experimental investigation on resistance and response of jacked model piles in sand

The installation resistance is important for selecting the type of jacked equipment. However, the calculation method of installation resistance has not been unified, and the radial stress distribution law of the soil surrounding the pile caused by installation pile is not yet clear.In this paper, a series of tests were performed on model pile jacked in sand, and the driven speed and pile length were considered. The changes of installation resistance, end resistance, radial stress and ultimate capacity of pile of jacked pile were analyzed. The pile length is the most significant factor that affects installation resistance, end resistance, radial stress and ultimate capacity of piles. Although the ratio of end resistance to installation resistance decreases with the depth, the end resistance is always dominant in the installation process of piles, and the ratio of end resistance to installation resistance is up to 75% when the depth is 12 times of pile diameter. The tendency for the radial stress of the soil surrounding the pile is closer to Rankine’s earth pressure with the depth. It is related to the compaction effect of jacked pile, increasing pile length or reducing the driving speed can improve the compaction effect of jacked pile. The radial stress of the soil surrounding the pile has a degradation phenomenon, which is related to the jacking pile and the pile rebound. Moreover, a modified methodology was proposed based on Terzaghi’s bearing capacity theory. Combined with the theory of Rankin passive earth pressure, the calculation formula of Rankin passive earth pessure correction for the radial stress of the soil surrounding the pile calculation was proposed, which can be used for the radial stress of the soil surrounding the pile after the installation pile.