反拱曲面X形异形桩产生附加应力计算方法研究

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

X形桩是一种具有反拱曲面的新型异形桩,该文以半无限体内受竖向集中力作用的Mindlin应力解为依据,通过沿X形桩桩周8个积分区间线积分,再沿桩长进行积分,得到了X形桩侧摩阻力沿桩身线性增长、沿桩周均匀分布、沿桩身矩形分布、沿桩周均匀分布侧摩阻力产生竖向附加应力系数的数值计算方法。通过沿X形桩截面3个积分区间面积积分,得到了X形桩均布端阻力在地基内产生竖向附加应力系数的数值计算方法。X形桩侧摩阻力和端阻力产生附加应力系数均随着外包方形截面边长和开弧间距增大而减小,随弧度数增大而增大。同周长X形桩侧摩阻力产生附加应力系数大于圆形桩,周长越大差别越大;同面积X形桩端阻力产生附加应力系数小于圆形桩,面积越大差别越大。

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 anX-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.