Monitoring Field Lift Thickness Using Compaction Equipment Instrumented with Global Positioning System (GPS) Technology

摘要

When constructing earthen embankments, it is essential that the soil be placed and spread in uniform lifts prior to compaction. To ensure that the resulting soil lifts are evenly compacted, typical compaction specification approaches place restrictions on the thickness that is acceptable for each soil lift. In current practice, it can be extremely difficult for a field inspector to verify that lift thickness requirements are being met when soil is being placed and spread over a large area, without the use of frequent surveying (which adds both costs and delays to earthwork projects). Recent advances in compaction control include the development of continuous compaction control (CCC) and intelligent compaction (IC) systems, which provide real-time monitoring and feedback about the operation and performance of soil compaction. Typically, CCC and IC compaction equipment is outfitted with a real-time kinematic global positioning system (RTK-GPS) that monitors and records the position of the compacter as the soil lift is being compacted. This paper suggests that geotechnical engineers use field RTK-GPS measurements that are made by CCC or IC equipment to monitor and control the thickness of compacted soil lifts. Data collected from a full-scale field study is used to illustrate the practical issues with using GPS measurements for field monitoring of lift thickness during construction of a roadway embankment, such as varying roller position from lift-to-lift and the measurement uncertainty associated with RTK-GPS measurement data. The use of both simple and sophisticated spatial analysis techniques are explored for interpolating measured field elevation data onto a uniform grid for lift thickness assessment. The resulting methodology that is presented can be utilized to build spatial maps of compacted soil lift thickness, a process that can be used to great benefit by field engineers who are trying to ensure the quality of compacted soil lifts.