Możliwości zastosowania zdalnego systemu monitoringu wgłębnego i powierzchniowego osuwisk w kopalni odkrywkowej węgla brunatnego na podstawie badań wykonanych w KWB Bełchatów w ramach projektu UE RFCS Slopes

Abstract

Possibilities of implementation of remote in situ and surface displacement landslide monitoring in lignite opencast mine based on the research conducted within the EU RFCS Slopes project.A b s t r a c t. Landslides in Polish opencast lignite mines are a serious problem for the efficiency of exploitation. They can also pose a threat to adjacent areas and the environment, and in some cases even jeopardize the continuity of lignite supplies to power plants. Such phenomena are associated with a number of factors, the most important of which are the geological engineering structure, groundwater conditions, unfavourable strength parameters of clayey soils and their usually relatively steep slopes. Counteracting such a phenomena, caused by mining activity, is usually difficult because of large size of landslides and the depth of exploitation reaching in some cases over 300 m. The paper presents the first application of on-line monitoring in a Polish opencast lignite mine. Performed in the Bełchatów Mine, in situ monitoring was complemented by satellite radar interferometry (PSI), LiDAR airborne laser scanning, and terrestrial laser scanning. Research within the RFCS EU SLOPES project “Smarter Lignite Open Pit Engineering Solutions” was performed by an international consortium from six European countries. In Poland, the research was located mainly on the western slope of the Bełchatów Field. In this area, in the Polish open pit lignite mine, on-line inclinometer, and a pore pressure monitoring system were the first located at the levels of +42 : –58 m a.s.l. Geological engineering investigations included 100 m depth core drilling, index laboratory tests, IL oedometer tests, CIU, CID triaxial tests, and numerical modelling. The total amount of in situ displacement, during the period December 2016–July 2019, reached 290 mm. The largest displacements up to 250 mm were recorded: to a depth of 45 m in the direction of slope inclination, and smaller ones up to 50 mm to a depth of 72.5 m. The displacements were accompanied by a decre ase in pore pressure values by more than 200 kPa. In other parts of the mine and adjacent areas, the satellite radar interferometry detected displacements up to 60 mm/year on the outer slopes of the Szczerców dump. It also allowed identification of the landslide hazard in other areas. Data obtained from in-situ monitoring and laboratory tests on the western slope of the Bełchatów Field were included in numerical modelling using the shear strength reduction method and the limit equilibrium method. This should allow helping for better recognition and warning of the existing hazards in the investigated area.