基于弯拉应力等效的地基当量回弹模量

Equivalent Resilient Modulus of Subgrade Based on Principle of Flexural-tensile Stress Equivalence

以往多层地基的顶面当量回弹模量大多是按弯沉等效得出的,该值对计算地基上面层或基层的弯拉应力是不适合的。为此,在弯沉等效的地基顶面当量回弹模量计算式的基础上,通过对荷载圆半径的修正,将弯沉等效转变为弯拉应力等效;进而,总结出了三层结构时单圆和双圆荷载的荷载圆半径修正系数回归公式,并拓展至多层结构;最后,通过工程实例证实,用弯沉等效的地基顶面当量回弹模量计算刚性或半刚性基层层底弯拉应力偏小13%~22%,而用弯拉应力等效的地基顶面当量回弹模量计算得到的基层层底弯拉应力与理论值的误差不超过1%。

In the past,the surface equivalent resilient modulus of multi-layer subgrade was obtained mostly based on the principle of deflection equivalence,which is not appropriate to calculate the flexural-tensile stress of surface or base course. For this reason,by modifying the load circle radius, the deflection equivalence is transformed into the flexural-tensile stress equivalence on the basis of the calculation method of the deflection equivalence surface equivalent resilient modulus of subgrade. Then,the regression formulas of the load circle radius correction coefficient of single circle and double circle of tri-layer structures are given,which is extended to multilayer structures. In the end,it is demonstrated by project examples that the bottom flexural-tensile stress under rigid or semi-rigid base calculated using the deflection equivalent subgrade surface equivalent resilient modulus is smaller and the deviation is about 13% ~ 22%,while the deviation of the flexural-tensile stress calculated by the presented method is no more than1%.