Estimation of geotechnical parameters of granular soil from various in-situ tests

In most cases of shallow foundations on granular soils the allowable bearing pressure is governed by the permissible settlement of the structure due to compression of soils under applied loading. Various in-situ penetration tests such as the cone penetration test and the standard penetration test are widely used for the characterization of granular soil since the direct determination of shear strength and compressibility of sand at different depths is impossible due to the difficulty in obtaining undisturbed samples in granular soil. However since the in-situ penetration tests do not provide direct measurement of soil properties, the empirical correlations that link the penetration results to soil properties evaluated from the direct methods such as field density tests and plate load tests are necessary for the assessment of granular soil properties. In this paper, the empirical correlation of sand compressibility is established using the results obtained from direct in-situ tests such as the plate load test, self-boring pressuremeter test and cone pressuremeter test, and indirect in-situ tests such as the dilatometer test and cone penetration test. The investigation includes study of the effect of sand density and prestress on the geotechnical parameters of sand using those direct and indirect in-situ tests as well as in-situ density tests.