STUDY ON CALCULATION METHODS OF ADDITIONAL STRESS OF X-SECTION ABNORMITY PILE WITH INVERTED ARCH SURFACE

The X-section pile is a new stye of abnormity pile with an inverted arch surface. Based on the Mindlin stress solution in a semi-infinite elastic body subjected to a concentrated force, the numerical calculation method of vertical additional stress coefficients due to the shaft resistance was obtained by the linear integrals of 8 integral intervals along the periphery on the side of X-section pile and then integrating along pile length. One loading case of the shaft resistance is of a rectangular distribution from top to bottom along the pile body and of a uniform distribution in circumference; another is of a triangular distribution from top to bottom along the pile body and of a uniform distribution in the circumference of an X-section section. The numerical calculation method of vertical additional stress coefficients in the foundation acting the uniformly distributed base resistance of an X-section pile was acquired according to surface integrals of 3 integral intervals on the X-section. The additional stress coefficients induced by the shaft and base resistances of an X-section pile decrease with the increasing of side length of circumscribed square and spacing of an open arc, and decline with the raising of template radian. In the case of the same perimeter, the additional stress coefficients due to shaft resistance of an X-section pile are larger than that of circular pile, and larger perimeter brings about a greater difference. Under the circumstance of the same area, the additional stress coefficients induced by the shaft resistance of an X-section pile are less than that of a circular pile, and larger area leads to a greater difference.