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Abstract The GPS displacement monitoring system developed by the authors was applied to an unstable steep slope along a national road in Japan. The system was available even during heavy rain, with 30–40 mm/hour, and it provided useful data for assessing the stability of the slope and for managing the safety of the roadway. Three-dimensional displacements could be measured continuously and precisely using appropriate methods for error correction. The applicability of the system for assessing slope stability is also discussed.
1. Introduction GPS is now being used widely for monitoring rock displacements, and it has been a useful tool for various rock engineering projects. The ISRM Suggested Method for Monitoring Rock Displacements using GPS has been published (Shimizu et al. 2014). The most important technical issue for the practical use of GPS in monitoring displacements is to perform realtime and precise monitoring even under adverse observation conditions, i.e., steep slopes, the existence of trees and walls above/around the sensors, bad weather conditions, etc. The authors have developed a precise real-time monitoring system which can automatically reduce the errors caused by meteorological factors and obstructions above the antennas (Shimizu et al. 2011).
In this research, the GPS system developed by the authors is applied to monitor the displacements of an unstable steep slope along a national road in Japan. Since local slope failures have occurred several times over the last 20 years, displacement monitoring has been conducted by borehole inclinometers and surface extensometers. Some of the instruments, however, have sometimes not worked due to large deformations, and it has become difficult to perform the monitoring continuously.
In order to overcome such trouble, the GPS monitoring system has been applied. The GPS monitoring system was available even during heavy rain, with 30–40 mm/hour, and it provided useful data for the safe management of the roadway. In this paper, three-dimensional displacement monitoring results are shown, and the applicability for assessing slope stability is discussed.
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