TN799 : Roadway’s blast-induced ground vibration effects on roof stability and caving step in longwall coal mining
Thesis > Central Library of Shahrood University > Mining, Petroleum & Geophysics Engineering > PhD > 2018
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Abstarct: Due to decrease in coal reserves, extraction from coal seams with a moderate and steep slope and feasibility studies of the steep coal stopes is necessary. Measuring blast-induced ground vibration is very important in terms of controlling and eliminating possible damages. Using laboratory and field data in the present study, numerical simulation of the mining process in longwall steep coal seam of K12 Eastern Alborz has been carried out. The section in the present study is at a depth of 410-480 meters and the average thickness of the coal laxyer is about 0.86 meters and the angle of inclination is 43 degrees.
Schmidt hammer tests, ultrasonic test, uniaxial and thiaxial compressive strength tests were performed on the rock specimen for estimating the parameters of the common failure criteria.
In field analysis, the results of the recorded vibrations caused by the roadways blast showed that, as expected, the cube root equation of charge weight is more consistent with existing data. baxsed on variable power of distance and charge weight, another equation was proposed using non-linear multi-variable regression method which has a very good accuracy in estimating ground vibrations and can therefore be used in similar formations with similar geotechnical parameters.
In finite difference model section, In general, deformation and stress redistribution pattern are in accordance with the previous research works. Support system evaluation was made by Sakurai’s critical strain for underground excavations and tunnels and the stopping’s lower part and the conveyance roadway were determined as critical locations.
In the final section, the numerical simulation of the explosion process at K12 working face was analyzed using empirical formulas and experimental-numerical combinations. Stress wave from explosion was derived from the widely-used empirical Starfield equation. The results of the numerical model showed that the combination of empirical-numerical method is suitable for modeling average-scale explosion in an underground space. The results showed that the maximum particle displacement values were very small and did not affect caving step of the excavation.
Keywords:
#Longwall #Numerical method #Steep coal seam #stress distribution #blast-induced vibarion #laboratory test Link
Keeping place: Central Library of Shahrood University
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Keeping place: Central Library of Shahrood University
Visitor: