Stronger granular layers are often placed as working platforms over weaker sand subgrade. The design of a working platform involves the calculation of a two-layer bearing capacity under rectangular loading. Existing design methods are either overly simplified, based on infinitely long strip loads and validated by a small number of small-scale 1g model tests, or rely on numerous or empirically derived charts that are difficult to use or implement into design software. In this paper a new and highly practical design method is proposed in which the bearing capacity is determined simply from the shear strengths and unit weights of the two soil layers. The method was derived from extensive finite-element analysis and finite-element limit analysis (FELA) parametric studies in both plane strain and axisymmetric geometries. It was validated against published physical model tests, other FELA analyses and existing design methods. It can be applied to all rectangular shape ratios with dry and saturated layers.

中文翻译：

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强颗粒层对弱砂的表面承载力

较强的颗粒层通常作为工作平台放置在较弱的砂土路基上。工作平台的设计涉及计算矩形载荷下的两层承载力。现有的设计方法要么过于简化，基于无限长的带状载荷，并通过少量小规模 1 g验证模型测试，或依赖难以使用或实施到设计软件中的大量或凭经验得出的图表。在本文中，提出了一种新的、高度实用的设计方法，其中承载力仅由两个土层的抗剪强度和单位重量确定。该方法源自平面应变和轴对称几何中的广泛有限元分析和有限元极限分析 (FELA) 参数研究。它根据已发布的物理模型测试、其他 FELA 分析和现有设计方法进行了验证。它可以应用于所有具有干层和饱和层的矩形比例。