Estimation of Pressuremeter Modulus from Geophysics in the Sonoran Desert: Fid-Bau Portal

Estimation of Pressuremeter Modulus from Geophysics in the Sonoran Desert

Shirer, Ashley / Rucker, Michael L. / Kandaris, Peter M.

Laterally-loaded short rigid drilled shaft foundations are the primary foundation used within the electric power transmission line industry to support steel monopole structures. Performance of these foundations is highly dependent on modulus of the subsurface that is best measured by the pressuremeter test. The pressuremeter test, however, is expensive to conduct and rarely performed. Correlations of pressuremeter modulus to blow counts and other index properties have been developed. But these correlations have high variability and may result in unconservative foundation design. Variability in correlations is due, in part, because of the differences in the direction of loading of the correlated properties and the direction of loading during pressuremeter testing. The shear wave velocity, measured using the surrogate surface wave velocity through refraction microtremor methods, can be used to measure small strain, shear modulus in the lateral direction. In theory, the intermediate strain modulus of the pressuremeter test is proportional to the small strain modulus derived from shear wave velocity. A correlation between intermediate and small strain moduli is developed here, based on geophysical surveys conducted at fourteen previous pressuremeter test locations throughout the Sonoran Desert of central Arizona.