石芽地基上桩顶作用效应计算

由于现行规范如JGJ94－94及GBJ7－89中，群桩基础各桩顶荷载分配采用统计的计算方法，未考虑山区石芽地基岩面起伏较大、群桩基础下各基桩长度、刚度不等的情况，可能为传导计算结果有一定的误差。针对覆盖土层多为上硬下软状态的红粘土，且具有超固结性，计算中分别采用竖向、横向地基抗力系数为常数，并考虑柱端嵌岩、扩底等情况，桩顶与刚性承台铰结条件，计算桩顶竖向、横向支承刚度系数。最后按矩阵位移法进行桩顶荷载分配计算。

Calculation of Pile Butt Effective Effect on the Changeable Depth Rock Base

Errors may occur when using the traditional calculatingmethod to distribute the pile butt load according to the criteria of JGJ94-94 andGBJ7-89,not considering the conditions in a mountainous district charecterized by achangeable depth of the rock with undulatory surface and foundation piles different inlength and stiffness under the pile group base.In accordance with the characteristics ofred clay,this paper pressents a new method in which modulus of ground vertical reactionand modulus of ground transversal reaction are adopted as constants to calculate pilebutt's vertical and transversal bearing stiffness factors,and the matrix displacementmethod is finally used to process the calculation of pile load distribution.