Model tests on pull-out mechanism of rotary excavation squeezed cast-in-place piles

Through the indoor small scale model tests, the optimal burial depth position and disc spacing of the bearing plate of the rotary excavated squeezed cast-in-situ piles are further determined, which provides the necessary basis for its application. In the silty clay layer, the 30 mm-pile diameter rotary excavation and expansion cast-in-situ pile is researched by the pull-up load. At the same time, an equal-diameter pile is set as a control group. The Q-s curve and the S-lgt curve of the equal-diameter pile and the spin-expansion and expansion-expansion pile are obtained under uplift load. The results show that both in terms of the uplift capacity and the anti-pull capacity, the rotary excavation squeezed cast-in-place piles are better than the equal-diameter ones, and the pull-out bearing capacity of the single pile is about 1.5~2.3 times that of the pile with the same diameter. In order to make sure that the bearing plate resistance is fully exerted, the bearing plate depth of the single plate pile is at least 6 times the pile diameter while that of the double-disc pile is at least 5 times the pile diameter.