Twenty years of coal mining-induced subsidence in the Upper Silesia in Poland identified using InSAR

The paper presents the results of terrain subsidence monitoring in Poland's Upper Silesian Coal Basin(USCB)mining area using Differential Interferometry Synthetic Aperture Radar(DInSAR)and Persistent Scatterer Interferometry(PSI).The study area accounts for almost three million inhabitants where mining which started in the 19th century,has produced severe damage to buildings and urban infrastructures in past years.The analysis aimed to combine eight different datasets,processed in two techniques,coming from various sensors and covering different periods.As a result,a map of areas that have been exposed to subsidence within 3045 square kilometers was obtained.The map covers a period of twenty years of intensive mining activities,i.e.1992-2012.A total of 81 interferograms were used in the study.The interferograms allowed not only to determine subsidence troughs(basins)formed from 1992 to 2012 but also to observe subsidence development over time.The work also included five sets of PSI processing,covering different temporal and spatial ranges,which were used to determine zones of residual subsidence.Based on InSAR datasets,an area of 521 square kilometers under the influence of mining activities were determined.Within the subsiding zones,an area of 312.5 square kilometers of the rapid increase in subsidence was identified on the interferograms.The study of combined different InSAR datasets provided large-area and long-term information on the impact of mining activities in the Upper Silesia Coal Basin.

An analytical model to predict the volume of sand during drilling and production

Over the past few decades, many optical fiber sensing techniques have been developed. Among these available sensing methods, optical fiber Bragg grating（FBG） is probably the most popular one. With its unique capabilities, FBG-based geotechnical sensors can be used as a sensor array for distributive（profile） measurements, deployed under water（submersible）, for localized high resolution and/or differential measurements. The authors have developed a series of FBG-based transducers that include inclination, linear displacement and gauge/differential pore pressure sensors. Techniques that involve the field deployment of FBG inclination, extension and pore-pressure sensor arrays for automated slope stability and ground subsidence monitoring have been developed. The paper provides a background of FBG and the design concepts behind the FBG-based field monitoring sensors. Cases of field monitoring using the FBG sensor arrays are presented, and their practical implications are discussed.