Effect of the inclined pile-soil arch in a soil landslide reinforced with anti-sliding piles

Aiming at the stability of a highway slope reinforced with anti-sliding piles, the mechanical behaviour of the inclined pile-soil arch in a soil slope reinforced with anti-sliding piles was analysed. Based on the pile-soil arching effect, a mechanical calculation model of the inclined pile-soil arch was established. According to the limit equilibrium condition of the inclined pile-soil arch, the analytical solution for pile width on the vault was obtained when the earth pressure on the pile side was distributed in triangular and parallelogrammic shapes. Based on the positional relationship of the vault of the pile-soil arch axis, the equations for inclined and horizontal pile-soil arches and the corresponding arching conditions were obtained. Analysis of a case study indicated that the sliding force of the pile-soil arch, pile width, cohesion, and internal friction angle of soil all influenced the arching condition of the inclined pile-soil arch and the designed pile spacing. When the sliding force exceeded 3500 kN/m, the calculated results according to the inclined pile-soil arch and horizontal arching models could not satisfy the arching condition. When the sliding force exceeded 2000 kN/m, the clear pile spacings calculated according to the inclined and horizontal pile-soil arch models were similar; in the case that the internal friction angle exceeded 15°, the clear pile spacings calculated based on the two models were similar; at a low internal friction angle, the results calculated according to the two models could not satisfy the arching condition; at a large internal friction angle, the results calculated based on the inclined pile-soil arch could satisfy the arching condition, while those based on the horizontal arching could not; when the pile width was less than 1 m, the results calculated based on the above two models could not satisfy the arching condition. Therefore, it is more reasonable to perform analysis by utilising the equation for the inclined pile-soil arch and the pile spacing calculated when the pile-soil load was distributed in triangular form was lower than that when the pile-soil load was distributed in parallelogrammic shape.