Abstract: Starting from the principle and the mechanic characteristic of forming soil arch of laterally loaded piles, and based on static equilibrium of the soil arch between two piles and soil resistance on its two end sections near two piles, the computation model is put forward. The equations involved space between two adjacent piles, thickness and height of soil arch are provided. One of the three parameters assumed, the other two could be solved. If one of thickness and height of soil arch is assumed, space between two adjacent piles will increase with shear strength parameters of the soil between two adjacent piles. Based on the characteristics of excavation engineering’s earth pressure, suggestions are given to deal with it. Landslide was cited to verify the formulae. The computed result is 1.85 m; and the anti-slide piles spacing which was used in the field is 1.8 m. The computed results are consistent with the evidence in the field.

Key words: anti-slide pile, soil arch between two piles, space between two adjacent piles, slope, excavation engineering