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软弱土层上的压实填土地基作为一种非均质地基广泛应用,但目前关于这种地基的破坏模式和承载力机制的研究还不够深入,工程中仍采用现行规范深度修正系数取值为2的方式进行设计。采用有限差分方法建立数值模型,研究了影响压实填土地基承载力深度修正系数的因素,并与现行规范推荐方法的取值进行对比。结果表明:填土越深、基础外超载越大,参与地基剪切破坏运动的土体体积越大,地基极限承载力越高;而随着填土宽度的增大,地基极限承载力先提高,后趋于稳定;砂土内摩擦角的增大也会提高地基极限承载力。总体来说,规范中的推荐值是偏于保守的,会造成承载力的浪费;而在下卧层强度很小、填土深度较大时该推荐值可能高估压实填土地基承载力,存在偏于不安全的可能,在工程设计时应予以考虑。
The compacted soil foundation on soft soil is widely used as an inhomogeneous foundation. However, the current research on the failure mode and bearing capacity mechanism of this foundation is still not deep enough. The current practice of deep correction coefficient Design for 2 ways. The finite difference method is used to establish the numerical model, and the factors that affect the depth correction coefficient of bearing capacity of compacted soil are studied and compared with the values of the current recommended method. The results show that the deeper the embankment is, the larger the overloading is, the larger the volume of soil involved in shear failure is and the higher the ultimate bearing capacity of foundation is. However, as the width of embankment increases, the ultimate bearing capacity of foundation increases first , Then tends to be stable. The increase of internal friction angle in sand will also increase the ultimate bearing capacity of foundation. In general, the recommended values in the specification are conservative, which will result in the waste of bearing capacity. However, when the strength of the subsoil is small and the depth of filling is large, the recommended value may overestimate the bearing capacity of the compacted fill, There is the possibility of insecurity, which should be taken into consideration in engineering design.