GPR monitoring of volumetric water content in soils applied to highway construction and maintenance

摘要

Detailed knowledge of the subsurface water content is important for highway design, maintenance, and repair. Transportation engineers can monitor the water content of subasphalt soils to estimate the soil stiffness as an index of the likely performance of a pavement and to evaluate the need for subsurface drainage retrofits. Conventional approaches for measuring water content include gravimetric sampling, time-domain reflectometry (TDR), and neutron probes, all of which are time-consuming and invasive. Additionally, each of these methods provides only point measurements; because soil moisture content can vary greatly over space and time, point measurements are of limited value when surveying over a large area and over a period of time. An alternative to these conventional methods is ground-penetrating radar (GPR), which can be used to quickly collect continuous, high-resolution water content estimates. GPR techniques can be used to estimate water content due to the sensitivity of electromagnetic velocity to water content.