Interpretation of SPT test results based on energy measurements

Abstract

The aim of this research is to present a rational approach for interpretation of Standard Penetration Test results from energy measurements, replacing the traditional procedures that have been used so far. The findings of this research will be used to estimate the strength and deformability parameters of soils, undrained shear strength of clays and relative density of sands. Parts of this research are the doctoral and the master research work of Juliana Azoia Lukiantchuki and Aleones José da Cruz Junior, respectively. Many criticisms have been raised regarding the SPT test, mainly due to the use of empirical correlations in the test results interpretation. Many of these correlations are based on practical observations with no scientific basis. The proposed rational approach requires the assessment of the energy that is actually transferred to the sampler, during the hammer blow. This energy can be assessed by monitoring the normal forces and accelerations in the sampler during the penetration into the soil. For this purpose, it will be used a short rod with load cells and accelerometers installed on it. This rod will be installed in between the sampler and the string of rods.For test results analyses, the problem of the propagation of longitudinal compression waves along the string of rods and sampler should be solved, adopting a fixed system of reference not connected to the rods-sampler-soil system. Field test results will provide means for a new scientific and rational approach for interpretation of Standard Penetration Test results. From these results the strength and deformability parameters of soils, undrained shear strength of clays and relative density of sands will be estimated. (AU)