Role of Footing Embedment on Tunnel–Foundation Interaction

Jingmin Xu,Nunzio Losacco,Alec M Marshall,Andrea Franza

doi:10.1061/(asce)gt.1943-5606.0002603

Abstract

This technical note investigates the effect of footing embedment depth on tunnel–structure interaction using geotechnical centrifuge testing. A 2-story framed building on separate footings, either resting directly on the surface or embedded in the soil, and subjected to tunneling-induced displacements is modeled. Measurements of the displacements of the footings and underlying soil, ground deformations, and structural distortions are presented. Results show that footing embedment increases foundation differential settlements and horizontal displacements, thereby causing a greater level of distortion within the frame. Furthermore, the embedded footings result in a larger magnitude of ground displacements and shear strains of the soil. Finally, modification factors and relative stiffness parameters are presented, indicating a greater effect of the embedment on horizontal deformations than the angular distortion of the bays.

Highlights

Prediction of tunneling-induced structural distortions and damage is a necessary stage of urban tunneling projects
To evaluate the impact of footing embedment, this technical note presents results from two plane-strain geotechnical centrifuge tests of tunneling in sand beneath a frame founded on separate footings resting either on the ground surface or embedded within the soil
The experimental results do not enable a full understanding of how these complex mechanisms combine to produce the observed results; further study, perhaps with the use of numerical modeling, is required in this regard. This technical note presented results from a centrifuge study on the effects of foundation embedment depth on tunneling-induced deformations of a framed building resting on separate footings

Summary

Introduction

Prediction of tunneling-induced structural distortions and damage is a necessary stage of urban tunneling projects. To evaluate the impact of footing embedment, this technical note presents results from two plane-strain geotechnical centrifuge tests of tunneling in sand beneath a frame founded on separate footings resting either on the ground surface or embedded within the soil.

Results

Conclusion