Determination of the presence of microstructure in a soil using a seismic dilatometer

This article shows an approach for investigating the presence of microstructure in a soil based on the results obtained by seismic dilatometer (SDMT). Three main parameters are considered: intermediate dilatometer test (DMT) parameters material index (I D ) and horizontal stress index (K D ) and small strain stiffness (G 0 ) obtained by shear wave velocity (V s ) measurements. The approach is engineering-oriented since it is simple, fast, inexpensive, and based directly on in situ measurements. We found that with increasing microstructure (cementation and aging) the ratio of measured to estimated G 0 increases, which could be used to improve interpretation of empirically determined geotechnical parameters from DMT results. Applications of a DMT-based, CPT-based and Vs-based correlations for determination of effective peak friction angle of sands, with and without presence of microstructure, are evaluated. Finally, we propose an approach to reducing the influence of microstructure on K 0 –K D correlation in a clay.