Use of Shear Wave Velocity for Foundation Design

Harry G Poulos

doi:10.1007/s10706-021-02000-w

Abstract

This paper describes an approach for utilizing in-situ measurements of shear wave velocity Vs to carry out preliminary and check design calculations for shallow and deep foundations. For estimates of foundation movements, Vs can be used directly to estimate the small-strain stiffness of the soil or rock strata, while for ultimate capacity calculations, use is made of empirical correlations between Vs and penetration resistance measures, which in turn are correlated to the foundation resistance characteristics. The approach is applied to a series of published tests on shallow footings, and on a series of pile load tests for a very tall building. For these cases, comparisons of the calculated with the measured load—settlement behaviour indicates that the suggested approach provides a reasonable, albeit somewhat conservative, level of agreement.

Highlights

Modern foundation design frequently involves the use of advanced numerical methods and software, which, in principle, enables more accurate calculations to be made of the anticipated behaviour of the foundation in question
This paper describes an approach for utilizing in-situ measurements of shear wave velocity Vs to carry out preliminary and check design calculations for shallow and deep foundations
For estimates of foundation movements, Vs can be used directly to estimate the small-strain stiffness of the soil or rock strata, while for ultimate capacity calculations, use is made of empirical correlations between Vs and penetration resistance measures, which in turn are correlated to the foundation resistance characteristics

Summary

INTRODUCTION

Modern foundation design frequently involves the use of advanced numerical methods and software, which, in principle, enables more accurate calculations to be made of the anticipated behaviour of the foundation in question. When using an approach that does not explicitly allow for an increase in stiffness with increasing depth below the footing, use can be made of approximate calculations using the Boussinesq theory to compute the distribution of vertical stress with depth, and to derive a relationship between the ratio of the modulus to the small-strain modulus, as a function of the relative depth below the foundation, and the applied stress level relative to the ultimate bearing capacity pu The agreement is not unreasonable, and it would appear that the approach adopted provides an acceptably conservative design approach for shallow footings on sand

Measured

CONCLUSIONS