Scanners, satellites, smart compactors, and drones: Emerging technologies for assessing compacted soil lift thickness

Abstract

Effective soil compaction requires sufficient compactor energy penetration. To achieve this goal, soil compaction specifications typically mandate a “not to exceed” lift thickness for a given layer of soil that is placed, spread, and compacted. Traditional techniques for field monitoring of soil lift thickness are personnel dependent, and add cost and time to projects. New and innovative approaches are emerging that have the long-term potential for more effective lift thickness monitoring at reduced cost. Three of these techniques are discussed in the current paper: (1) non-destructive lift thickness scanning using a magnetic pulse induction lift thickness scanner (scanners), (2) continuous real-time kinematic (RTK) global positioning system (GPS) surveying using a global navigation satellite system (GNSS) such as GPS, GLONASS, BeiDou, Galileo, etc in conjunction with local receivers mounted on “intelligent” soil compactors (satellites and smart compactors), and (3) unmanned aerial vehicle (UAV) image acquisition coupled with photogrammetric analysis/surveying techniques (drones). The accuracy of point-specific measurements made using each of these techniques is of critical importance. This paper describes the results from a field study that was conducted to assess the relative accuracy of these three techniques by monitoring the lift thickness of a full-scale earthen test embankment. Measured field results indicated that emerging technologies such as magnetic pulse induction scanning can accurately estimate soil lift thickness within 0.4 cm when compared against physical soil lift thickness measurements. Other emerging technologies, such as UAV-based surveying techniques, also provided reliable estimates of soil lift thickness measurements, which were accurate to within 1.2 cm of physical soil lift thickness measurements. Additionally, some of these emerging techniques (satellites, smart compactors, and drones) offer the advantage of providing near-continuous soil lift thickness measurements along the entire embankment, which can be useful for building spatial maps of compacted soil lift thickness.