对地基弹性均压系数与基础底面积关系的研究

STUDY ON THE RELATIONSHIP BETWEEN THE COEFFICIENT OF ELASTIC UNIFORM COMPRESSION AND BASE AREA

根据各向同性的均质的弹性半空间理论,地基的弹性均压系数Cz与基底面积的平方根F成反比。但这一理论结果与大量的试验结果不符。在分析产生这种差异根本原因的基础上,提出在理论上假定地基在半空间范围内为各向同性的均质的弹性体是不符合实际的结论。并指出随着深度的增加,土体的弹性模量也在不断增加。考虑这一因素后,地基土的弹性均压系数Cz的变化比之随F的变化速率要缓慢得多。同时还指出,《动力机器基础设计规范》(GB 50040-96)对分层地基条件下确定地基弹性均压系数Cz的不合理性。

According to the theory based on semi-infinite homogeneous isotropie elastic body, the coefficient of elastic uniform compression changes in inverse proportion to the square root of base area. However, the theoritical conclussion disagrees with a number of results of tests. The paper demonstrates the essential reason causing the disagreement. The paper considers that assuming soils in range of semi-infinite to be a homogeneous isotropie elastic body is not in accord with practice. In fact, the elastic modulus of soils changes with depth. After considering the factor, the variation rate of coefficient Cz with base area F will be much lower than that with √F. This conclusion is demonstrated by a number of computational results. Meanwhile, the paper indicates that the determination of value of Cz for layered soil structure characterized by different mechanical properties, adopted by ＂Code for Design of Dynamic Machine Foundation＂（ GBS0040 - 96） is unreasonable.