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Powered roof support – rock strata interactions on the example of an automated coal plough system

Herezy Ł., Janik D., Skrzypkowski K.

Studia Geotechnica et Mechanica

2018

Vol. 40, nr 1

46--55

The study summarises the operating characteristics of the powered roof support (shield) used in an automated plough system. Investigated longwall support units were controlled automatically or by section engineers and positioned in the 'saw tooth' configuration with respect to the longwall face (automatic mode) or linear to the face. Shield pressure data have been analysed in order to identify the impacts of particular factors on the pressure increase profiles. The analysis was supported by the Statistica software to determine the statistical significance of isolated factors. Equations governing the leg pressure at the given time instant were derived and the roof stability factor 'g' was obtained accordingly, recalling the maximal admissible roof displacement method recommended by the Central Mining Institute (Poland). In the current mining practice, its values are used in monitoring of strata behaviour as indicators of shield–strata interactions, particularly in the context of roof control in longwall mining. It is vital that the method used should be adapted to the actual conditions under which the longwall is operated. In the absence of such adaptations, there will be major discrepancies in results. The conclusions section summarises the current research problems addressed at the Department of Underground Mining, in which the support pressure data in longwall operations are used. The first aspect involves the delineation of deformations of a longwall main gate about 100 m ahead of the face. The second issue addressed involves the risk assessment of roof rock caving or rock sliding in the tail gate. Another aspect involves the standardisation of local conditions to support the methodology of interpreting shield–strata interactions in the context of work safety. These methods are being currently verified in situ.

Numerical modeling of stress field in rock strata from surface deformation surveys

Szostak-Chrzanowski A., Chrzanowski A., Bazanowski M.

Zeszyty Naukowe. Górnictwo / Politechnika Śląska

2007

z. 278

451-460

The surface deformation measurements provide information that may be used in determination of the redistribution of stresses within the rock strata. A methodology has been developed in which displacements at discrete points obtained from geodetic monitoring surveys can serve as an input to deterministic modeling of stress distribution. The knowledge of the stress distribution provides a better understanding of the deformation mechanism. The method has been applied to a complex problem of explaining irregular ground subsidence caused by mining activity and hydrological changes in a large potash mine in eastern Canada.

Wyniki pomiarów odkształceń na powierzchni dostarczają informacji, które mogą służyć do wyznaczenia rozkładu naprężeń wewnątrz górotworu. W opracowanej metodzie przesunięcia punktów otrzymane z geodezyjnych pomiarów są użyte do opracowania deterministycznego modelu rozkładu naprężeń, z którego można otrzymać lepsze zrozumienie mechanizmu odkształceń. Metoda ta została zastosowana do wytłumaczenia nieregularnego osiadania powierzchni na terenie górniczym dużej kopalni potasu we wschodniej Kanadzie. Nieregularne osiadanie zostało wywołane robotami grórniczymi i zmianami hydrologicznymi.