Monitoring of soil nailed slopes and dams using innovative technologies

Abstract

This paper presents (a) an integrated automatic real-time slope monitoring system using a conventional slope monitoring package and a multi-antenna Global Positioning System (GPS) package and the field monitoring results, (b) monitoring of soil nailed slopes by optical fiber strain sensors, and (c) moni- toring of a model dam by optical fiber sensing bars. The authors also introduce new developments of special Fiber Bragg Grating (FBG) based sensors and potential applications for monitoring settlement profiles, vertical settlements, and lateral movement of slopes, dams, and foundations under both static and dynamic loading. 70% of the land area in Hong Kong is hilly. Rain- induced landslides occurred before, having resulted in hundreds of fatalities. Landslides are still a great threat to loss of human life and property, not just in Hong Kong, but also in many other regions all over the world. Monitoring the slope movements can evaluate the stability of the slopes and give a pre-warning to people before failure. For new cut slopes, removing soil may cause settlements of adja- cent buildings. Monitoring the slope and ground movements can provide valuable data whether or not the movements are excessive and endanger the buildings. Traditional approaches using a survey methods and manually operated instruments may be used to mea- sure settlements and lateral movements of a slope. However, these two approaches are difficult to be used for a dangerous slope since operators are at risk when working on the slope. The measurement accuracy is not satisfactory in many cases. Auto- matic and real-time slope monitoring is much better. This paper introduces (a) development of an inte- grated slope monitoring system using a conventional slope monitoring package and a multi-antenna Global Positioning System (GPS) package and the field mon- itoring results of a soil nailed slope, (b) monitoring of soil nailed slopes by optical fiber strain sensors, and (c) monitoring of a model dam by optical fiber sens- ing bars. Main monitoring results are presented and discussed.