Pavement Evaluation to Detect Potential Voids Under the Surface After the Historic Flood of June 2013 in the City of Calgary

摘要

On June 20, 2013, The City of Calgary (The City) witnessed one of the worst floods in its known history. The flood was so devastating that about 100,000 people were evacuated from their residences. Public and private infrastructure suffered hundreds and hundreds of millions of dollars in damages. A state of local emergency (SOLE) was declared for 15 days. Many roadways were washed out or had developed multiple sinkholes. The affected pavement network indicated about 250 sinkholes during only the time of SOLE. Some of the roadways were showing multiple sinkholes and it was believed that the flood water was flowing in channels under the pavement surface. This channelling may have created voids that collapsed with insufficient support for the material above. To demonstrate due diligence, The City decided to investigate the roads indicating multiple sinkholes for potential voids or other conditions that may not have surfaced yet. A pavement evaluation was conducted on affected portions of five roadways (MacLeod Trail, 1st Street SE,11 Avenue SE, 25 Avenue SW, and 38 Avenue SW) for the detection of potential voids under the pavements. A forensic non-destructive testing program utilizing Road Radar™ and Falling Weight Deflectometer (FWD) testing was developed. Two survey passes per lane, one in each wheelpath, was carried out. Anomalies underneath the pavement structure were identified with the Road Radar™ system. The locations identified with anomalies were tested with FWD for further analysis. The spacing and location of the FXT) tests were determined based on the severity, size, distribution and location of anomalies. Benchmarking criteria for the evaluation of the FWD deflections were established. All data was compiled into GIS that was used to reference all components of the data and aid analysis. This paper discusses the process of survey, Road Radar™ , FWD testing and analyses, a brief literature search, and developing deflection criteria and benchmarking. Conclusions and recommendations are presented at the end.