In Situ Determination of Void Ratio and Compactness in Saturated Soils Using a Partially Automated Measuring System Based on Microwaves
Void ratio and compactness are two of the principal parameters used for the geotechnical characterization of soils. Amongst others, they determine the deformation, settlement or liquefaction potential, which in turn might significantly impair the quality as well as the performance of any soil foundation. Direct measurement of the natural void ratio, i.e. the parameter typically used as indication for the soil compactness, is particularly difficult since it requires undisturbed samples. Because of the difficulty to obtain such samples in their undisturbed state, indirect methods such as: SPT, NSPT or CPT, to mention only the most commonly used ones, have been developed and are widely used. However, such indirect methods have their limitations and often fail, especially with heterogeneous soils also containing coarser materials. Additionally, results interpretation is done by indirect, empirical correlations, and is often affected by uncertainty. This situation gave rise to develop a more reliable and flexible approach, allowing a direct quantitative measure of the in situ void ratio of saturated soils. In this article a newly developed, partially automated, measuring system based on microwaves, is presented. The measurement method and an application example will be illustrated.
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