Determining reasonable spacing between two adjacent piles is one of the important contents in the anti-slide pile design. In this study

the anti-sliding ability of pile is mainly combined with two parts: the anti-sliding ability from the pile back face and ability from the pile side. Assuming the anti-sliding ability of the pile is putting into full play

a new spacing calculation formula between two adjacent anti-slide piles has been presented based on Mohr-Coulomb strength criterion. The landslide thrust of the present method is balanced by the pile-soil shear friction on pile side surface

and the soil-soil shear friction within the ultimate shearing thickness of soil arching on the pile back face. Both the pile-soil and the soil-soil shear frictions are simply assumed to have linear distributions along its shearing thickness. Based on the proposed method

a parameter study has been conducted to investigate the influence of multiply factors

such as cohesion of landslide soil

slide force and cross section size of plie on the pile spacing. The results show that the anti-sliding ability from the pile side

which mainly controlled by the pile side width

plays an important proportion in the whole anti-sliding ability of the pile. Moreover

the maximum spacing between adjacent anti-slide piles is significantly influenced by the cohesion and internal friction angle of landslide soil and the width of piles.