An analysis of the quasi-static expansion of a cylindrical or spherical cavity in an infinite dilatant elastic-plastic soil is presented Closed form solutions for the stress and displacement fields in the soil during the expansion of the cavity are given The soil is modelled as linear elastic-perfectly plastic, using a non-associated Mohr-Coulomb yield criterion An explicit solution for the pressure-expansion relationship is obtained with no restriction on the magnitude of the deformation It is found, in particular, that the radius of the cavity increases indefinitely as the cavity pressure approaches a finite limiting value This limiting pressure can be determined analytically with the help of a single expansion of an infinite series The novelty of the new solution lies in the introduction of dilation to the analysis of large strain expansion Examples of the implications of the new analysis in geotechnical engineering are discussed L'article presente une analyse de l'expansion quasistatique d'une

Finite cavity expansion in dilatant soils: loading analysis

Estimation of the axial capacity of piles driven into sand involves considerable uncertainty, and design rules are generally not consistent with the physical processes involved. This Paper reviews current understanding of the factors that determine the axial capacity of piles driven into sand, and outlines a new framework for design which takes account of the physical processes, is consistent with the existing database of load test results, and is sufficiently flexible to permit refinement as new data become available. It allows for the effects of confining stress on the frictional and compressibility characteristics of sand, and hence on end-bearing capacity. In keeping with field observations, shaft friction is assumed to degrade with driving of the pile past a particular location, from an initial maximum value linked to the local end-bearing capacity. The resulting design approach is compared with field data, and effects of factors such as the direction of loading are discussed. L'estimation de la resi...

/pdf/design-of-driven-piles-in-sand-5aa2i0muor.pdf

Design of driven piles in sand

Preface 1. Stress and strain 2. Elastic and inelastic material behaviour 3. Yield 4. Plastic flow 5. Collapse load theorems 6. Slip line analysis 7. Work hardening behaviour A. Non-Cartesian coordinate systems B. Mohr's circles C. Principles of virtual work D. Extremum principles E. Drucker's stability postulate F. The associated flow rule G. A uniqueness theorem for elastic-plastic deformation H. Theorems of limit analysis I. Limit analysis and limiting equilibrium.

/pdf/plasticity-and-geomechanics-2q6ls1qy4b.pdf

Plasticity and Geomechanics

Cone tip resistance is the most widely measured quantity in the cone penetration test. A brief review is made of presently available theories for the analysis of cone resistance. The theories are presented in forms that enable direct comparisons among them. The simplifying assumptions made in the analysis using various theories are emphasized. In the light of experimental evidence and the fundamental principles of mechanics, the limitations and advantages of each theory are assessed. Comparison with limited experimental data indicates that cavity expansion theories give the closest overall agreement between predicted and measured penetration resistance.

Analysis of Cone Resistance: Review of Methods

The paper summarises the experience gained by the writers in the interpretation of the cone penetration test (CPT) and flat dilatometer test (DMT) for the assessment of the geotechnical properties of sands. In the first part of the paper, the problem of determining the relative density (D R ) as function of the penetration test results and ambient stress (σ'), for silica sands, is dealt with. In the second part of the paper, the assessment of the peak angle of shearing resistance (φ' p ) is dealt with. The attention is given to the use of the Bolton's strength-dilatancy theory in order to estimate φ' p . Engineering correlations, based on Bolton's work, are proposed allowing estimation of φ' p as function of penetration resistance and σ', taking into account the compressibility and the curvilinear shear strength envelope.

Evaluation of Relative Density and Shear Strength of Sands from CPT and DMT

Closed form solutions are presented for the expansion of cylindrical and spherical cavities in an ideal, cohesive frictional soil. An explicit solution for the pressure-expansion relationship can be obtained for infinitesimal (small strain) deformations. For finite deformations it is necessary to adopt a numerical approach to obtain the complete pressure-expansion relationship and it is found that the cavity pressure approaches a limiting value for infinite deformation. It is, perhaps surprisingly, possible to determine the precise value of this limiting pressure analytically. It is suggested that the small strain solution for a cylindrical cavity is applicable to the interpretation of pressuremeter tests in sand, and that the solutions for limit pressures have application to the problem of pile installation and the end bearing pressure of deep foundations. L'article presente des solutions de forme fermee pour l'expansion de cavites cylindriques et spheriques dans un sol ideal coherent a frottement. On pe...

S. K. Yeung

Papers

Cavity expansion in cohesive frictional soils