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.