۱- Introduction

۲- Analytical Analyses

۳- Verification

۴- Parameters Analyses

۵- Conclusions

References

Abstract

Existing analytical method to predict tunneling-induced pile deformation is generally based on the Winkler foundation model that neglects shear effects of soil, which is not sufficient for engineering practice. A simplified solution based on Kerr foundation model is presented in this study to investigate the tunnel-soil-pile interaction. In order to improve the accuracy of the prediction for tunneling-induced free-field movements, the cavity contraction theory is utilized in the first stage which receives a higher accuracy than the solution proposed by Loganathan and Poulos (1998). In the second stage, the soil free-field displacement is imposed on the existing pile, and the simplified solution for pile deformation governed by the disturbance of passive displacement is established based on the Kerr foundation model, which can take account of the soil shear effects. The applicability and accuracy of the simplified solution are then verified by several cases including the reported analytical solution, centrifuge modeling tests and observed data in situ. Good agreements are obtained in the comparative analyses, which demonstrates that the proposed solution can serve as an alternative approach for conservatively estimating tunneling-induced pile deformation in the preliminary design in clay. Furthermore, the parametric analysis associated with the pile deformation has also been performed. As a result, it is of primarily theoretical and practical significance to investigate the influence of soil shear effects on the tunnel-soil-pile interaction mechanics.

Introduction

Owing to the fast urban development and the rapid growth of urban population, the operative infrastructures are exceedingly demanded in cities. Special attention is gathered on the growing awareness of further constructing the urban underground space. In current, tunnels are more and more frequently encountered in urban area in an attempt to relieve the burden of surface traffic. However, tunnel constructions inevitably cause soil stress changes and ground movements, which may adversely affect the existing structures. For example, tunnel excavation closely spaced to piles will unavoidably cause the piles to deform. To avoid possible damage to adjacent structures, two important aspects must be fully considered by the designer: the pile displacement induced by the deformation of surrounding soil in order to ensure structural serviceability; the additional forces imposed to the piles by the soil displacement in order to ensure structural integrity. Current approaches for the free-field displacement and the tunnel-soil-structure interaction can be classified as the analytical derivation, the numerical simulation, and the in-situ test.