Negative skin friction of piles considering nonlinear consolidation of soil

The objective of this study is to discuss the widespread problem of negative skin friction in soft soil foundation based on pile-soil interaction. According to the characteristics of soft soil compression curve, the hyperbolic consolidation theory is adopted to reflect the nonlinear response of soil consolidation, and the derivation of soil subsiding with depth as well as time is also achieved. Moreover, the Gibson theory is introduced to consider the heterogeneity of soil by combining the shear strain for pile-soil interface with a hyperbolic model of shear stress, and a load transfer function is established, indicating that it can reflect the characteristics of nonlinear increase with depth for the initial shear stiffness between the pile and soil. On this basis, the pile skin friction, pile axial force and the position of neutral point are obtained by an iterative method. In addition, field tests are used to verify the proposed method and the influences of the factors such as parameters of compression test, soil consolidation degree, pile diameter, pile length as well as surcharge on negative skin friction and position of neutral point. The comparative results indicate that the proposed method is feasible in the practice.