Title:
Deformation and failure mechanisms of granular soil around pressurised shallow cavities
Deformation and failure mechanisms of granular soil around pressurised shallow cavities
Author(s)
Patino-Ramirez, Fernando
Ando, Edward
Viggiani, Gioacchino
Caicedo, Bernardo
Arson, Chloé
Ando, Edward
Viggiani, Gioacchino
Caicedo, Bernardo
Arson, Chloé
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Abstract
The deformation patterns and failure mechanisms of pressurised cavities at shallow depth are of relevance to many geotechnical applications, including tunneling and horizontal directional drilling. In this paper, we present an experimental study of a reduced-scale pressurised cavity under geostatic stress, in order to measure the effect of cavity length, vertical stress and soil density on soil deformation and failure. x-ray computed tomography is used to acquire images of the system at key stages of the cavity inflation process. A closed shaped failure region developed around the cavities, beyond which, shear planes of elliptic paraboloid shape formed, extending from the bottom of the cavities all the way to the free surface. The plane strain assumption did not hold beyond the central portion of the longest cavity tested (L = 6D). The volumetric strain and porosity changes inside the shear bands showed significant dilation in dense specimens, but contraction in loose specimens. The average orientation and the thickness of the shear bands were in agreement with those found in the literature for passive
arching mechanisms (anchoring). The orientation of the principal strains around the cavity follows catenary shapes, similar to those displayed in active trapdoor mechanisms.
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Date Issued
2021
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Post-print