Abstract: During the reinforcement of dynamic compaction foundation, real tamping pit positioning satisfying design requirement is a basis for the reinforcing effect. Traditional manual lofting methods suffers several problems in determining the position of tamping pit, such as inefficiency and difficulty in result checking. This study develops a real-time method for calculating tamping pit position based on GNSS and magnetic sensors, together with a corresponding system of real-time monitoring on pit tamping. This system can realize accurate real-time positioning of the pit during dynamic compaction construction. It monitors the position of the monitoring equipment center via GNSS positioning equipment mounted on the ramming machine, using a magnetic azimuth sensor to collect the tamping pit azimuth data relative to the compactor, so that an automatic full-tamping-process real time monitoring is achieved. To discretize the time sequence of tamping pit locations, a spatial clustering analysis is used to extract accurate pit positioning information. This method is validated against the measurement of dynamic compaction construction for the resettlement project of the Baihetan dam. Results show that it can effectively determine the position coordinates of the tamping pit and improve the intelligence level and positioning efficiency, thus help the quality evaluation of strong compaction construction.

Key words: Dynamic compaction construction, tamping pit positioning, quality control, cluster analysis