Sběr dat pro vývoj metody hodnocení porušování pevného nadloží na základě důlně měřických pozorování

The assessment method of roof failure is based on the interpretation of mine surveying observations depending on the pettern of rock mass. This method conduces to recognize the condition, when a firm roof deformation occurred. If no complete failure of firm overlaying strata occurs, the surroundings of the mined out area is considerably surcharged and the risk of anomalous geo-machanical phenomena substantially increaases.Metoda hodnocení porušování pevného nadloží je založena na interpretaci důlně meřických pozorování v závislosti na charakteru horského masivu. Tato metoda přispívá rozpoznání stavu, kdy došlo k deformaci pevného nadloží. Pokud nedojde k prolomení pevných nadložních vrstev, je okolí vydobytého prostoru značně přitíženo a podstatně se zvyšuje nebezpečí vzniku anomálních geomechanických jevů

Optimization of satellite insar techniques for monitoring of subsidence in the surroundings of Karvina mine: Lazy plant

This paper deals with issues related to convenient monitoring of subsidence due to longtime mining activities of Czech Karviná Mine: Lazy plant, using satellite SAR interferometry (InSAR) techniques. It maintains approaches for optimizations of differential InSAR, especially including available filtering possibilities. It was realized that current SAR satellites were not able to appropriately evaluate deep subsidence as it occurs in Czech mining sites. Other issues are related to the presence of dense vegetation. Data from previous and only available L-band SAR satellite ALOS demonstrates its high potential in this area of interest. However, only a few acquisitions are available of the mining site disallowing usage for purposes of continuous monitoring of subsidence in the area. Processing results of InSAR techniques of the Lazy plant are presented in this paper.Web of Science101656

Documentation of landslides and inaccessible parts of a mine using an unmanned uav system and methods of digital terrestrial photogrammetry

Quite a big boom has recently been experienced in the technology of unmanned aerial vehicles (UAV). In conjunction with dense matching system, it gives one a powerful tool for the creation of digital terrain models and orthophotomaps. This system was used for the documentation of landslides and inaccessible parts of the Nástup Tušimice mine in the North Bohemian Brown Coal Basin (Czech Republic). The images were taken by the GATEWING X100 unmanned system that automatically executed photo flights an area of interest. For detailed documentation of selected parts of the mine, we used the method of digital terrestrial photogrammetry. The main objective was to find a suitable measurement technology for operational targeting of landslides and inaccessible parts of the mine, in order to prepare the basics for remediation work

Specifics in the formation of substituence through in the Karvina part of the Ostrava-Karvina coalfield with the use radar interferometry

Deep extraction of minerals is accompanied by deformations of the strata overlying extracted coal seams. Deformations of overlying layers run up to the surface where a subsidence trough gradually forms. The movement of individual surface points is curvilinear, spatial and, in relation to the time pattern, not uniform. In some cases, during the formation of a subsidence trough, temporary uplifts of the surface occur. This paper gives a particular area in which uplifts of the surface occurred when the rigid overlying strata was disturbed. The character of deformations of the overlying rocks is evaluated on the basis of a comparison of the results of the measurement of subsidence of the surface using geodetic methods with the development of mined-out areas and with their extracted thickness. For specifying the time of failure of the overlying strata, also information obtained from a system of continuous monitoring of seismic events is used. The spatial extent of the subsidence trough is identified by satellite radar interferometry (InSAR) techniques applied to TerraSAR-X images. The subsidence wave was possible to detect using a short temporal difference of 11 days between satellite radar images. This shows the potential of short-temporal high resolution InSAR for monitoring of progress of subsidence troughs. A good knowledge of extents and shape of subsidence trough formation in time allows to verify values of parameters used for prediction purposes. Application of the short temporal InSAR appears very effective for spatio-temporal studies of the current subsidence trough development and helps understanding the physical process as well as identifying deviations from the behaviour expected by models.Web of Science13326926

Application of satellite radar interferometry (PSInSAR) in analysis of secondary surface deformations in mining areas. Case studies from Czech Republic and Poland

Secondary deformations are ground movements occurring in areas of ceased underground mining. These are associated with delayed readjustment of rock mass resulting in subsidence, discontinuous deformations (sinks, cracks, etc.) due to destruction of underground, usually shallow, workings, and elevation of ground surface in response of rock mass to rising groundwater levels following the end of mine water drainage. Comparative analysis of secondary deformations in two former mining areas in the first period after cessation of underground hard coal mining is the subject of this study. We used ERS-1/2 and Envisat satellite radar interferometry data processed with PSInSAR technique and GIS to map vertical (in satellite's line of sight, LOS) movements of the surface and analyse them in relation to location of coal fields and underground water table rise. In the study, two areas have been compared, the Ostrava city in the Czech part of the Upper Silesian Basin and the Walbrzych Coal Basin in Poland. The results of analyses based on the results of PSInSAR processing between 1995 and 2000 for the Walbrzych site indicate uplift (up to +12 mm/year) in closed parts of coal fields and subsidence (up to nun/year) in areas of declining mining. Results of PSInSAR analysis over the Ostrava site indicate decaying subsidence after mine closures in the rate of up to -6 mm/year during 1995-2000. Residual subsidence and gentle uplift have been partly identified at surroundings of closed mines in Ostrava from 2003-2010 Envisat data. In Walbrzych gentle elevation has been determined from 2002 to 2009 in areas previously subsiding.Web of Science15218517

Multitemporal monitoring of Karvina subsidence troughs using Sentinel-1 and TerraSar-X interferometry

Satellite SAR interferometry (InSAR) allows to observe borders of subsidence troughs created in undermined areas. There is a possibility to evaluate a subsidence velocity in the accuracy of a mm/year for the stable reflectors of the radio signal, e.g. buildings. We apply Permanent Scatterers (PS) and Quasi-PS (QPS) techniques for monitoring of mine-caused subsidence in the Karvina area situated in the Czech part of Upper Silesian Basin. We use PS technique as effective for observation of displacements of built structures (e.g. buildings) and QPS for monitoring of spatio-temporal development of subsidence troughs. The results reveal information valuable for an identification of deviations from expected effects of mining activities on the land surface and for the infrastructure which are potentially affected by the subsidence. We perform the processing of Sentinel-1 and high resolution TerraSAR-X to find how the lower spatial resolution of Sentinel-1 SAR affects the reliability of results. The assets of these new sensors, especially the short revisit time, can overcome the basic limits of InSAR methods connected with temporal lags between available SAR images. In previous Karvina area datasets (ERS, Envisat, Alos satellites) the basic temporal step used to be around one month. During such temporal length significant changes occured in vegetation cover or in cultivated soil causing a loss of coherence of radar measurements. In addition to this, the amount of subsidence of Karvina troughs has often exceeded detection limits of the SAR systems. A significant increase of the reliability of evaluated subsidence also in areas with a moderate vegetation cover is expected with the launch of Sentinel-1B since the short-term interferograms would not be affected by a full decorrelation.Web of Science141595

Mechanism of rigid overlaying of carboniferous strata failure in face mining in the case of a multiseams deposit

The technique of assessing the failure of rigid overlying strata is applicable to deep mining with thick coal seams (a thickness of more than 1 m in the Ostrava–Karvina Coalfield), and in one case to longwall mining with controlled caving. The assessment of failure of rigid overlying strata makes it possible to distinguish whether the rigid overlying strata of rocks has been deformed or whether a strutting arch has been formed over the goaf below which is an area that is free from stress. Good knowledge of the mining, technical and geological conditions of a given site is a prerequisite for successful evaluation. There are advantages to utilising surface measurements for interpreting the effects of changes in rock mass, especially in areas of high overlying strata. The practical importance of failure assessment of overlying strata consists in determining the size of the mined-out area where the deformation of the rigid overlying strata occurred, which is dependent on the character of the rock mass. This paper is set in the context of the expected width of the goaf during deformation of rigid overlying strata within parameters that describe the mining and geological conditions of the locality. Changes in the area of the goaf, based the results of tensometric measurements, will also be placed in context.Web of Science10219518

EFFECTS ON THE FINAL INTENSITY OF INPUT FORCES IN LONGBOLTS INSTALLED AT THE MINING OPERATION 2 AREA, OKD, INC.

In the deep coal mines of OKD, Inc., both bolts and long bolts of different designs are used for the rock massif and steel arch support reinforcement. Continuous measurement of forces in 6 strand bolts and 1 cable bolt (long bolts, generally) was carried out during the trial operation of the modified Room and pillar mining method at Mining operation 2, site North, OKD, Inc. Hydraulic dynamometers were installed on these long bolts and a monitoring of forces took place throughout the life-time period of the mining panel No. V. From this measurement, a knowledge of their different load behavior with respect to the input stress parameters was obtained. The input intensity of the force applied to the bolting elements is burdened by losses of various kinds. The subject of the article is a description and analysis of the intensity of the initial stressing force applied to individual long bolts (with a threaded clamping bush or wedge barrel) and quantization of short-term stress losses with a description and analysis of these

Displacements Monitoring over Czechia by IT4S1 System for Automatised Interferometric Measurements Using Sentinel-1 Data

The Sentinel-1 satellite system continuously observes European countries at a relatively high revisit frequency of six days per orbital track. Given the Sentinel-1 configuration, most areas in Czechia are observed every 1–2 days by different tracks in a moderate resolution. This is attractive for various types of analyses by various research groups. The starting point for interferometric (InSAR) processing is an original data provided in a Single Look Complex (SLC) level. This work represents advantages of storing data augmented to a specifically corrected level of data, SLC-C. The presented database contains Czech nationwide Sentinel-1 data stored in burst units that have been pre-processed to the state of a consistent well-coregistered dataset of SLC-C. These are resampled SLC data with their phase values reduced by a topographic phase signature, ready for fast interferometric analyses (an interferogram is generated by a complex conjugate between two stored SLC-C files). The data can be used directly into multitemporal interferometry techniques, e.g., Persistent Scatterers (PS) or Small Baseline (SB) techniques applied here. A further development of the nationwide system utilising SLC-C data would lead into a dynamic state where every new pre-processed burst triggers a processing update to detect unexpected changes from InSAR time series and therefore provides a signal for early warning against a potential dangerous displacement, e.g., a landslide, instability of an engineering structure or a formation of a sinkhole. An update of the processing chain would also allow use of cross-polarised Sentinel-1 data, needed for polarimetric analyses. The current system is running at a national supercomputing centre IT4Innovations in interconnection to the Czech Copernicus Collaborative Ground Segment (CESNET), providing fast on-demand InSAR results over Czech territories. A full nationwide PS processing using data over Czechia was performed in 2017, discovering several areas of land deformation. Its downsampled version and basic findings are demonstrated within the article

Hodnocení stavu porušení pevného nadloží dobývaných slojí v závislosti na charakteru horského masivu

As a result of the deposit caving, the original stress balance of the rock mass is affected; therefore, the stress always increases around the mined-out workings. The stress increase results in the stope surroundings compression distinguished by a certain surface subsidence measurable (the surface also features substantially smaller horizontal shifts as the second vector component of the general movement towards the mined-out workings metacentre). Determination of this subsidence value in relation to the extent and thickness of the mined-out workings is important to recognize the conditions under which a complete failure of the firm overlying layers occurred. At the first extraction in the area, that means failure in the whole thickness of overlying carboniferous rocks.Vlivem dobývání ložiska na zával se narušuje původní napěťová rovnováha horského masivu, proto kolem vydobytého prostoru dochází vždy ke zvýšení napětí. Důsledkem zvýšeného napětí dochází ke stlačení okolí výrubu, které se projevuje určitým, měřitelným poklesem povrchu (na povrchu dochází také k výrazně menším vodorovným posunům jako druhé složky vektoru obecného pohybu směřujícího do metacentra vydobytých prostor). Určení této hodnoty poklesu s ohledem na rozsah a mocnost vydobytých porubů je důležité pro rozeznání stavu, kdy již došlo k celkovému porušení pevných nadložních vrstev. Při prvním dobývání v oblasti to znamená porušení celé mocnosti nadložních karbonských hornin