The net cross-sectional area is 10.71 m2. Typical deep mining problems such as high pressure, high temperature, and severe deterioration of the surrounding rock have emerged in the right working face. As shown in Fig. 3, at the Pinggang Coal Mine, multiple attempts at using pillarless ...
where: A is the initial undamaged cross-sectional area, At is the total cross-sectional area of the damaged part of the coal body, A1 is the cross-sectional area of the damaged part by stress, A2 is the cross-sectional area of the damaged part by water. Separate consideration of the ...
The position (b) of the rhombic shape section 3 is shrunk in width into a peak shape, the cross sectional shape is smoothly shrunk in the width direction in sequence toward the position (b) shrunk in width, thus press molding can be easily applied. When the rhombic shape sections 3 are...
Cross-sectional area of pillar w p, h : Width and height of pillar, respectively u : Pillar deformation u c : Pillar deformation corresponding to peak strength, uc = (1/m)1/m u0 u t : Deformation at the inflection point of the pillar F–u curve, ut = (1 + ...
FIG. 1A is a cross-sectional view of a semiconductor die in the form of a flip chip 12 connected to a substrate 14 by means of elongated pillars 16 to illustrate an embodiment of the invention. As shown in FIG. 1A, the space between the die 12 and substrate 14 is filled with an un...
The results from the 3D laser scanner in test #2 showed that the gap between the blasted burden and the new face in the region of the caved masses became approximately 0.6 m. Therefore, the overall compaction of the caved material was 5%, and the same cross-sectional area as the backfill...
Example pillars were characterised by FIB-SEM cross-sectional examination to assess microstructural changes and re-deposition of vaporised material. The final selected laser parameters were able to produce a stable high-aspect ratio pillar in 4501 s, 1600 µm high with tip diameter 138 µ...
(c) Cross-sectional TEM images that confirm the presence of a nanoscale thin layer of P(VDF-TrFE) on both top part and side walls of the micropillar. (d) FT-IR spectra and (e) XRD analysis of the P(VDF-TrFE) core-shell micropillars. Full size image Fourier transform infrared (FTIR...
Above the coal pillar, a "double-peak" stress distribution pattern is observed, with the maximum vertical stress reaching 43.7 MPa, and the stress concentration coefficient ranging from 1.78 to 3.2. (2) During the extraction of the sectional coal pillar, there is a stress arch composed of...
The retention of coal pillars with inappropriate sectional dimensions has become an important factor influencing the occurrence of rock burst. For example, under long-term high static loads, coal pillars are prone to damage. Additionally, dynamic loads induced by fractures in the overlying strata ...