贯入双层土中的混凝土管桩桩模与土体作用研究

采用ABAQUS有限元法模拟了混凝土管桩桩模贯入试验过程中贯入阻力的变化规律和桩周土体的水平位移，通过试验数据与计算结果的对比，验证了采用有限元法模拟桩模贯入过程的适用性。在此基础上，探讨了桩模贯入深度、上层土体厚度、桩径、土体强度和桩土摩擦系数在桩模贯入过程中，对桩周土体水平位移和桩模贯入阻力的影响。结果表明：桩周土体水平位移与土体径向位置、桩径关系紧密，并得到了桩周土体水平位移与土体径向位置、桩径之间的关系式；上层土体厚度、桩径和桩土摩擦系数对桩模贯入阻力影响较大，总结了桩模贯入阻力与上层土体厚度、桩径和桩土摩擦系数之间的关系式。最后采用土体附加水平应力云图解释了贯入深度对桩周土体水平位移的影响；桩模贯入上软下硬土层时，桩周土体最大水平位移出现在上层软土中，计算结果可为现浇混凝土管桩在施工设计和桩土相互作用分析提供参考依据。

Research on interaction between soil and cast-in-place concrete pipe pile casing penetration into double-layered clay

In this paper, the ABAQUS large deformation finite element (LDFE) method was used to get the penetration resistance and the horizontal displacement of soil during pile penetration test. The applicability of the finite element method to the simulation of the penetration process was verified by the comparison of the experimental and calculated data. On this basis, the influences of upper layer thickness, penetration depth, soil strength, pile diameter and pile-soil friction coefficient on lateral deformation of soil and casing penetration resistance during the casing penetration process were discussed. The results show that the horizontal displacement of the soil around the pile is closely related to the radial position and pile diameter, and the relationship between the horizontal displacement of soil and the soil radial position and pile diameter is obtained. The influence of the upper layer thickness, pile diameter and pile-soil friction coefficient on pile penetration resistance is great. Formulas are proposed through data fitting to predict the maximum penetration resistance of casing using pile diameter and pile-soil friction coefficient. Finally, the influence of penetration depth on horizontal displacement of soil is explained by the soil additional horizontal stress.The maximum horizontal displacement appears in the upper soft soil when the pile casing is penetrated into the soft over stiff soil. The calculation results can provide reference for the construction design and the interaction between pile and soil during the cast-in-suit concrete pipe pile installation process.