Displacement monitoring using GPS at an unstable steep slope and the performance of a new low-cost GPS sensor

The Global Positioning System (GPS) has been recognized as an effective tool for monitoring displacements in Geotechnical Engineering. The third author and his colleagues developed a GPS monitoring system that can automatically and continuously monitor three-dimensional displacements with mm accuracy. The system has been applied to hundreds of projects in Japan, i.e., landslides, slopes along highways, subsidence, dam operations, bridge construction, etc. In this paper, an overview of the existing GPS displacement monitoring system is described. A practical application of GPS to monitor an unstable steep slope along a national road in Japan is shown. The monitoring results could provide useful information for assessing the stability of the slope. In addition, the performance of a new GPS sensor is investigated to verify its applicability and reliability for displacement monitoring. It is found that the new sensor has the potential to be used in practical monitoring.