Monitoring of Deep-Seated Mass Movements

A GPS monitoring system has been developed for the investigation of landslides. The applicability of this system is
demonstrated by monitoring the deep-seated mass movement Gradenbach, Austria. 17 GPS surveys of at least 48
hours duration each were carried out during the last seven years. The motions can be determined with an accuracy of
4 mm in horizontal direction and 8 mm in vertical direction. The accurate GPS results suggest that the velocity
pattern of the deep-seated mass movement at Gradenbach is not uniform but rather intermittent, i.e., highly
accelerated motions are followed by periods of creeping. The causes for this pattern are unknown.
For the investigation of the mechanics of this phenomenon a strain rosette for in-situ measurements of local distance
changes is being developed. It consists of three embedded extensometers at a separation in orientation of 120°. The
sensors are long gauge (5 m) fibre optical interferometers of SOFO type yielding a precision of 2 μm for absolute
length changes and 0.01 μm for relative length changes. The concept, design and first test results will be presented.

External Contact Person: 
Fritz K. Brunner
Bibliographic reference: 

Fritz K. Brunner, Helmut Woschitz, Klaus Macheiner. The 3rd International Conference on Structural Health Monitoring of Intelligent Infrastructure
Vancouver, British Columbia, Canada, November 13-16, 2007. Monitoring of Deep-Seated Mass Movements.