Effects of existing piles on lateral resistance of new piles

Abstract Cyclic lateral-loading centrifuge tests were conducted on a new pile located at the center of 2×2 existing piles, to evaluate the effects of the existing piles on the new pile's lateral resistance when the piles of an old building are left derelict. Furthermore, two-dimensional FEM analyses of the horizontal cross sections of the pile–soil systems were carried out. The centrifuge test results show that the lateral resistance of a new pile, located among existing piles, shows slight increases. The existing piles increase the horizontal subgrade reaction of the upper part of the new pile, but slightly decrease that of the lower part of the new pile. Numerical analyses reveal that the key to whether an existing pile increases the horizontal subgrade reaction of a new pile or not, is the soil displacement at the location of the existing pile. An existing pile increases the horizontal subgrade reaction of a new pile when the existing pile displacement is less than the soil displacement caused by the new pile. Conversely, an existing pile decreases the horizontal subgrade reaction of a new pile when the existing pile displacement is greater than the soil displacement caused by the new pile.