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Geophysical and analytical determination of overstressed zones in exploited coal seam: a case study

Chlebowski Dariusz, Burtan Zbigniew

Acta Geophysica

2021

Vol. 69, no. 2

701--710

A variety of geophysical methods and analytical modeling are applied to determine the rockburst hazard in Polish coal mines. In particularly unfavorable local conditions, seismic profling, active/passive seismic tomography, as well as analytical state of stress calculating methods are recommended. They are helpful in verifying the reliability of rockburst hazard forecasts. In the article, the combined analysis of the state of stress determined by active seismic tomography and analytical mod eling was conducted taking into account the relationship between the location of stress concentration zones and the level of rockburst hazard. A longwall panel in the coal seam 501 at a depth of ca.700 m in one of the hard coal mines operating in the Upper Silesian Coal Basin was a subject of the analysis. The seismic tomography was applied for the reconstruction of P-wave velocity felds. The analytical modeling was used to calculate the vertical stress states basing on classical solutions ofered by rock mechanics. The variability of the P-wave velocity feld and location of seismic anomaly in the coal seam in relation to the calculated vertical stress feld arising in the mined coal seam served to assess of rockburst hazard. The applied methods partially proved their adequacy in practical applications, providing valuable information on the design and performance of mining operations.

Czynniki warunkujące zmienność modułu odkształcenia gruntów spoistych

Wdowska M. K., Wudzka A.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

2006

Vol. 15, No. 1

64--74

The paper presents analysis of factors that subject a value o f Young's m odulus of cohesive soils. This parameter is indispensable in a design process of all soil structures and any engineering structure founded on soil. According to Polish practice expressed in Polish Standard PN-81/B-03020, value of Young’s modulus is uniquely related to soil kind and liquidity index. The paper presents considerably larger number of factors that influences deformation of soils with particular reference to strain range, State of stress and its history. From this results that Young's modulus should be perceived rather as deformation characteristic dependent on many factors and not material constant. The theses presented in the paper are exemplified by experimental data.