روش پیش بینی انرژی لرزه ای ناشی از بهره برداری جبهه کار بلند مبتنی بر تغییر در فرونشست زمین

A method of forecasting total seismic energy induced by longwall exploitation, based on changes in ground subsidence, is presented in the form of a linear regression model with one with one independent variable. In the method, ground subsidence is described with a cross-section area of a subsidence trough Pw along a line of observations in the direction of an advancing longwall front, approximately along the axis of the longwall area. Total seismic energy is determined on the basis of seismic energy data of tremors induced by exploitation. The presentation consists of a detailed method and evaluation of its predictive ability for the area of longwall exploitation within the region of one of the coal mines in the Upper Silesian Coal Basin. This method can be used for forecasting the total seismic energy released by tremors within the area directly connected with the exploitation, in which the seismic activity induced by this exploitation occurs. The estimation of the parameters of the determined model should each time be carried out with investigations of the correctness of the model. The method cannot be applied when the number of recorded phenomena is small and when there is insufficient data to make it possible to calculate the index Pw.

Mining exploitation of hard coal in Poland has been carried out for many years and in most cases, within areas of induced seismic activity. There is a constant increase of natural hazards in active mines. Approximately 45% of the present output comes from strata considered to be of high risk rock burst hazard. The potential level of seismic hazard has increased. Changes in the status of rock burst and tremor hazards are significantly affected by mining technology and the state of knowledge enabling forecasting and introducing suitable preventive actions. This is why the problem of induced seismic activity is a subject of many investigations. As a result, new measurement methods, extensive elaboration, interpretation and seismic hazard forecasting methods have been developed in recent years. Forecasting is always one of the most important tasks during exploitation under induced seismic activity. Given these conditions, measures are in place to minimize the risk of these adverse effects. In general, hazards in areas under study and research are established on the basis of past data, which enables us to determine seismic activity indices, updated as new data are acquired. The forecast can include surroundings of a single excavation or areas directly connected with exploitation. Tremor generation processes are considered a function of time. The indices of seismic activity of a rock mass, induced by exploitation, can be the number of tremors registered or energy released in a given period of time. Seismic activity levels can be characterized as index defining deformation processes of rock mass layers, which can generate tremors and indices of surface deformation [1], [2], [3], [4], [5] and [6]. This study presents a method of forecasting total seismic energy induced by longwall exploitation, based on changes in ground subsidence, using a linear regression model with one independent variable. The method presented has been elaborated on the basis of results of research carried out since 2004 in the Institute of Mining of the Silesian University of Technology [7], [8], [9], [10], [11] and [12]. The ground subsidence is described for by a cross-section area of a subsidence trough Pw along an observational line, in the direction of the advancing longwall front, approximately in the middle of the face of the longwall. The forecast is executed on the basis of a defined linear regression model of total increasing seismic energy with respect to increases in the Pw area. After verifying the model and in case it is considered sufficiently accurate, the forecast of a total seismic energy is executed within a time period T, during which the cross-section area reaches its predicted value. The level of accuracy of executed forecasts is defined on the basis of the relative error of the ex ante forecast. This forecast accuracy is evaluated based on the average absolute percentage error of ex post forecasts. The study consists of a detailed algorithm and evaluation of its predictive abilities for the area of longwall exploitation, executed within the region of one of the coal mines in the Upper Silesian Coal Basin.

This study shows a method of forecasting the total seismic energy induced by longwall exploitation according to the changes in ground subsidence, using a linear regression model with one independent variable. Ground subsidence was described with the cross-section area of a subsidence trough Pw along a line of observations in the direction of an advancing longwall front, approximately in the middle of the face of the longwall. The forecast of total seismic energy was executed within a time period T, in which the cross-section area reached its predicted value, was made on the basis of the fitted linear regression model of total increasing seismic energy according to increases in the area Pw. Method can be used for forecasting the total energy of tremors released in the region including an area of current exploitation, in which the induced seismic activity occurs. Estimation of the parameters of the calculated model should each time be connected with investigation of the correctness of the model. This method cannot be applied when the number of recorded phenomena is small and when we do not have enough data making it possible to calculate the index Pw. Evaluation of the predictive ability of the selected model was positive. The relative ex ante errors over the examination periods of forecasting did not exceed 5%, which means that the forecasts are acceptable. The average absolute percentage error of ex post forecasts, calculated for the forecast periods equaled 11%, which is mainly caused by lower seismic activity observed in the region than the activity in the period used for model development.