Accurately predict the resistance of caisson penetrating in stratified soil deposits is an engineering challenge for application of such foundation system. This paper performs large deformation finite element analysis to investigate the penetration behavior of caisson foundations in non-uniform clay interbedded with a sand layer. The numerical model is validated by comparing with previously testing data, in which good agreement is obtained. Parametric study is then conducted to examine potential influencing factors, including the penetration depth, the top clay layer thickness, clay properties, and the thickness of the second sand layer. It is found that the soil failure mechanism and corresponding penetration resistance of caisson foundations in clay-sand-clay are significantly different from that in pure clay or sand soil deposits, especially for the part in the middle sand layer, where the peak resistance could be overestimated by 10–40% using the current design codes without considering the influence of the weak underlying layer. In this study, based on intensive numerical modeling results, approximating expressions are proposed to describe the unique trends of the resistance profile for caisson penetration in non-uniform clay interbedded with a sand layer soil deposit, which can provide design guide for engineering application.

准确预测沉箱在分层土壤沉积中的穿透阻力是此类地基系统应用的工程挑战。本文进行了大变形有限元分析，以研究沉箱地基在非均匀粘土夹砂层中的渗透行为。通过与先前的测试数据进行比较来验证数值模型，获得了良好的一致性。然后进行参数研究以检查潜在的影响因素，包括渗透深度、顶部粘土层厚度、粘土特性和第二层砂层的厚度。发现粘土-砂-粘土中沉箱地基的土体破坏机理和相应的抗侵能力与纯粘土或砂土沉积物显着不同，尤其是中砂层部分，在不考虑弱底层影响的情况下，使用现行设计规范可将峰值电阻高估10-40%。本研究基于密集的数值模拟结果，提出了近似表达式来描述与砂层土层互层的非均匀粘土中沉箱穿透阻力剖面的独特趋势，可为工程应用提供设计指导。