Geomechanical data are never sufficient in quantity or adequately precise and accurate for design purposes in mining and civil engineering.The objective of this paper is to show the variability of rock properties at t...Geomechanical data are never sufficient in quantity or adequately precise and accurate for design purposes in mining and civil engineering.The objective of this paper is to show the variability of rock properties at the sampled point in the roadway's roof,and then,how the statistical processing of the available geomechanical data can affect the results of numerical modelling of the roadway's stability.Four cases were applied in the numerical analysis,using average values(the most common in geomechanical data analysis),average minus standard deviation,median,and average value minus statistical error.The study show that different approach to the same geomechanical data set can change the modelling results considerably.The case shows that average minus standard deviation is the most conservative and least risky.It gives the displacements and yielded elements zone in four times broader range comparing to the average values scenario,which is the least conservative option.The two other cases need to be studied further.The results obtained from them are placed between most favorable and most adverse values.Taking the average values corrected by statistical error for the numerical analysis seems to be the best solution.Moreover,the confidence level can be adjusted depending on the object importance and the assumed risk level.展开更多
In the original publication the resolution of Figures 1 and 2 need improvement.The correct version of figures is available in this correction.The original article has been corrected.
Presented measurement results of roof rocks and wall rock movements of un- derground development workings after their drifting.The research was carried out in the coal mine workings with standing-and-roof bolting supp...Presented measurement results of roof rocks and wall rock movements of un- derground development workings after their drifting.The research was carried out in the coal mine workings with standing-and-roof bolting support.There were various density of the support,so the aim of the special monitoring programme was to determine movement intensity of rock mass in the premises of the heading area.There were four types of re- search did by the authors.They measured convergence,roof layers separation using tell- tales and sonic probes and load bearing of the headings' roofs by hydraulic dynamometers Evaluation of fracture zone around the heading and investigation the load zone caused by failed roof rocks may become a basement for the determination of support parameters of the workings.The combined system of standing support and roof bolting seems to be an essential for underground headings protection.展开更多
The paper presented assessment of sealed fire states in underground coal mines by so-called 'fire characteristic', which graphically described tendencies of fire gas components-oxygen, nitrogen, carbon dioxide...The paper presented assessment of sealed fire states in underground coal mines by so-called 'fire characteristic', which graphically described tendencies of fire gas components-oxygen, nitrogen, carbon dioxide, carbon monoxide and hydrocarbons-in time. In order to mark gas components tendencies in time the authors applied the time series analysis. The case studied confirmed, that analysis of fire gas components tendencies in time and their correlation allow to elicit proper conclusions about fire state assessment. Assessment of fire states based on single value of fire indexes without considering their trends in time and correlation between trends of gas components would give wrong results The suggested method can appropriately indicate fire states in a sealed area.展开更多
The ash contents in coal particles were examined in the paper dependably on particle size and its density. So, the two-dimensional regressive function Z = Z（P, D） was the searched object, where Z is random variable ...The ash contents in coal particles were examined in the paper dependably on particle size and its density. So, the two-dimensional regressive function Z = Z（P, D） was the searched object, where Z is random variable describing ash contents, P---density and D---particle diameter. This dependence was determined based on experimental data concerning the coal of type 31. For this coal, the method of ordinary kriging was applied to calculate the values of random variable Z. This method required the proper selection of so-called variogram function, in which four forms were considered in this paper in purpose to select the best solution. The given results were then evaluated by the mean standard error value and compared with empirical data.展开更多
文摘Geomechanical data are never sufficient in quantity or adequately precise and accurate for design purposes in mining and civil engineering.The objective of this paper is to show the variability of rock properties at the sampled point in the roadway's roof,and then,how the statistical processing of the available geomechanical data can affect the results of numerical modelling of the roadway's stability.Four cases were applied in the numerical analysis,using average values(the most common in geomechanical data analysis),average minus standard deviation,median,and average value minus statistical error.The study show that different approach to the same geomechanical data set can change the modelling results considerably.The case shows that average minus standard deviation is the most conservative and least risky.It gives the displacements and yielded elements zone in four times broader range comparing to the average values scenario,which is the least conservative option.The two other cases need to be studied further.The results obtained from them are placed between most favorable and most adverse values.Taking the average values corrected by statistical error for the numerical analysis seems to be the best solution.Moreover,the confidence level can be adjusted depending on the object importance and the assumed risk level.
文摘In the original publication the resolution of Figures 1 and 2 need improvement.The correct version of figures is available in this correction.The original article has been corrected.
基金the Ministry of Science and Higher Education Nr of Projects(4T12A00229)
文摘Presented measurement results of roof rocks and wall rock movements of un- derground development workings after their drifting.The research was carried out in the coal mine workings with standing-and-roof bolting support.There were various density of the support,so the aim of the special monitoring programme was to determine movement intensity of rock mass in the premises of the heading area.There were four types of re- search did by the authors.They measured convergence,roof layers separation using tell- tales and sonic probes and load bearing of the headings' roofs by hydraulic dynamometers Evaluation of fracture zone around the heading and investigation the load zone caused by failed roof rocks may become a basement for the determination of support parameters of the workings.The combined system of standing support and roof bolting seems to be an essential for underground headings protection.
文摘The paper presented assessment of sealed fire states in underground coal mines by so-called 'fire characteristic', which graphically described tendencies of fire gas components-oxygen, nitrogen, carbon dioxide, carbon monoxide and hydrocarbons-in time. In order to mark gas components tendencies in time the authors applied the time series analysis. The case studied confirmed, that analysis of fire gas components tendencies in time and their correlation allow to elicit proper conclusions about fire state assessment. Assessment of fire states based on single value of fire indexes without considering their trends in time and correlation between trends of gas components would give wrong results The suggested method can appropriately indicate fire states in a sealed area.
文摘The ash contents in coal particles were examined in the paper dependably on particle size and its density. So, the two-dimensional regressive function Z = Z（P, D） was the searched object, where Z is random variable describing ash contents, P---density and D---particle diameter. This dependence was determined based on experimental data concerning the coal of type 31. For this coal, the method of ordinary kriging was applied to calculate the values of random variable Z. This method required the proper selection of so-called variogram function, in which four forms were considered in this paper in purpose to select the best solution. The given results were then evaluated by the mean standard error value and compared with empirical data.
