地层成层性对基床系数的影响分析

Influence of soil stratification on coefficient of subgrade reaction

地下、建筑及交通工程对基床系数的使用局限于均质弹性半空间中地面一点的反应,没有反映地层成层性、空间性及各向异性对基床系数的影响,计算误差较大,且后续工程处理较为复杂。为考虑地层成层性对基床系数的影响,基于弹性层状理论进行地基梁变形分析,并与Winkler地基模型的解答进行对比,提出考虑土层有限压缩特性及成层特性下的基床系数表达式。结合算例验证本文方法的合理性与适用性,并给出对应于不同土层厚度与软硬分布情形下,基床系数表达式中相关修正系数的设计图表。对于具体工况,先视作均质有限压缩地基,由k∞与土层总厚度H查图表确定kH,再根据土层成层特性及kH确定最终k取值。

The employment of coefficient of subgrade reaction is limited to the reaction of ground surface in the homogeneous elastic half-space,not demonstrating the influence of soil stratification,extensity and anisotropy against the coefficient of subgrade reaction,and would cause a large calculation error and complicated post processing in engineering treatment.This paper carried out analysis of foundation beam deformation with reference to elastic stratification theory and compared with the solution of Winkler foundation model,then proposed the expression of subgrade reaction coefficient when taking limited compressible soil layers and special characters of stratification of the soil into account.This paper tested the validity and feasibility of the proposed method in combination with some examples.What￠s more,the design charts of correction factors in the expression of subgrade reaction coefficient are provided in terms of different distribution of elastic modulus and thickness of soil layers.For a specific case,the soil is first considered as homogeneous limited compressible foundation,and calculated k H with k∞ and the total soil thickness H,and finally got k by kH and the specific stratification of the soil.