Centrifuge tests on soil-nailing reinforcing effect in scattered row piles and soil nailing for excavations

A centrifuge study on pile-soil nailing (PSN) is carried out by Tongji University. The results of five groups of tests performed on the centrifuge in Tongji University show that the soil nailing of PSN can greatly increase the stability of cuttings. The length of soil nails has significant effects on the stability, failure mode and soil-arching effect of PSN. When the ratio of the nail length to the excavation depth (L/H) is 0.33, the soil-arching effect is very obvious, and the sliding surface morphology of PSN is similar to that of scattered pile retaining structure, However, when the L/H ratio is 0.67, the soil-arching effect is not obvious, and the sliding surface morphology of PSN is similar to that soil-nailing retaining structure. The pile internal forces of PSN decreases with the increase of the length of soil nails.