大直径桩端阻力面积修正系数研究

桩端阻力和桩端直径呈非线性关系,随着桩端直径的增加而逐渐减小。本文根据线弹性理论和非线性弹性理论分别求得大直径灌注桩桩端阻力的面积修正系数的上限解和下限解,得到了桩端土承载力标准值与桩端直径的非线性关系和桩端土承载力面积修正系数与桩端直径的非线性关系。与现行建筑桩基技术规范相比,当桩径 0．80～3．00 m时,规范给定的面积修正系数稍大于理论上限值,其它桩径范围的桩端面积修正系数均在理论值的上、下限范围。当桩径0．80～2．00 m时,按规范给定的面积修正系数修正后的承载力标准值稍大于理论上限值, 其它桩径范围按规范修正后的桩端土承载力标准值均在理论值的上、下限范围。

STUDY OF COEFFICIENTS MODIFYING AREA OF END OF PILE WITH LARGE DIAMETERle ACTED ON BY END-PILE RESISTANCE

The relationship is a nonlinear between end-pile resistance and end-pile diameter, and the end-resistance of the pile with large diameter decreases more and more as the pile diameter increases. The solutions of upper limit and lower limit of the area modificatory coefficients and the standard values of bearing capacity of end-pile subsoil based on the linear elastic and nonlinear elastic theory respectively in this paper. Meanwhile, the nonlinear relation curves of η-D and qp-D are given. The area modificatory coefficient and the standard values of the bearing capacity are between the upper limit and lower limit by comparison of code values with the theory values. But the area modificatory coefficients of large diameter pile is a little bit than the theoretical result when the pile diameter is equal to 0. 80～3. 00 m according to the code. The standard values modified of bearing capacity of the large diameter pile is a little bit than theoretical result when the diameter is equal to 0. 80～2.00 m according to the code.