Abstract: In the existing theoretical analysis, laminar rock mass of sliding bed is normally equivalent to homogeneous or horizontal non-homogeneous body for calculations of the internal forces and deformation on the anti-sliding pile. However, most of slide beds in Three Gorges reservoir area are composite inclined rock mass. Firstly, numerical simulations using the 3DEC software were conducted to examine the relationships of the effective scope of the anti-sliding pile with the cross-section width and depth of pile. The upper and lower limits of the effective scopes of the pile were determined. Secondly, a formula was developed for the comprehensive foundation coefficient (KZi) of sliding bed on composite inclined rock mass within the effective scope of pile by the area equivalent. Finally, several formulas of internal forces and displacement considering KZi, were deduced on the elastic anti-sliding pile. Moreover, correspondingly MATLAB calculation programs were compiled. Taking the Majiagou landslide as an example, the internal forces and displacement of anti-sliding pile under the sliding surface were calculated by the equivalent method, the horizontal layer foundation coefficient method and KZi-based method, respectively. Comparisons between the KZi-based method and the horizontal layer foundation coefficient method show that the displacement of sliding surface by the former is greater than that of the latter (14.6%) and the difference of internal force is negligible. According to the displacement of sliding surface, the displacement of pile top calculated by the KZi-based method is similar with that of field monitoring, while it is smaller by a conventional method and dangerous for design. Thus, the KZi-based method can provide theoretical support for the area of composite inclined rock mass on the design of anti-sliding piles.

Key words: sliding bed on composite inclined rock mass, anti-sliding pile, effective scope, comprehensive foundation coefficient, internal forces and deformation