Subgrade assessment using automated dynamic cone penetrometer to manage geo-infrastructures

Abstract

For the efficient management of geo-infrastructures in the field, engineering properties of the subgrade should be reliably and rapidly investigated. The objective of this study is to estimate and compare the strength and stiffness parameters of subgrades using portable in-situ devices. An automated dynamic cone penetrometer (ACP), dynamic cone penetrometer (DCP), and light falling weight deflectometer (LFWD) are adopted and applied at nine points of soft ground in South Korea. The N-value from the ACP (N-ACP), which efficiently assesses the relatively deep subgrade, is correlated with the dynamic cone penetration index (DCPI) and dynamic deflection modulus (E-vd). Test results show that the DCPI and E-vd can be estimated in terms of N-ACP. In particular, the relationship between E-vd and N-ACP is improved when the strain influence factor of the target ground is considered. For the assessment of strength and stiffness parameters, the California bearing ratio (CBR), relative density (D-r), internal friction angle (phi), and elastic moduli determined by the plate loading test (PLT), soil stiffness gauge (SSG), falling weight deflectometer (FWD) are estimated using N-ACP. The ACP test with the relationships between engineering parameters and N-ACP may be an effectively method to assess the overall characteristics of the subgrade.