Deformation Field Evolution and Failure Mechanisms of Coal–Rock Combination Based on the Digital Speckle Correlation Method

Abstract

The stability of a deep composite roof is a powerful guarantee for the safe and efficient production of a coal mine. The coal–rock combination, the single rock or coal bodies have different bearing capacity; thus, we can accurately obtain the deformation field evolution and failure mechanisms of the combination, which is useful in the deformation control of a composite roof. In this study, based on the digital speckle correlation method (DSCM), a uniaxial compression test was applied to coal–rock combinations with different height ratios. The results revealed that the compressive strength, elastic modulus, and secant modulus of the combination gradually decreased, while the decreasing amplitude weakened with the increase of coal height. Additionally, the strain field map of the combination had different characteristics in different stages. As the height of the coal body continuously increased, the gradient of the strain cloud and the area of local strain increase moved upwards. Moreover, the cracks caused by the failure of the coal body in the combination triggered the failure of the rock body. According to the test results, two principles are proposed for the deformation control of the composite roof, and are expected to be useful in applications for the similar geological conditions.

Monitoring and correction of the stress in an anchor bolt based on Pulse Pre‐Pumped Brillouin Optical Time Domain Analysis

“…Bolts are vital to the advancement of underground excavation in engineering work, such as subway tunnels and coal mines, as they connect broken rock mass, enhance the stability of underground coal mine roadways and surrounding rock, and reduce the occurrence of rock burst . In countries such as China where huge amount of coal is mined, problems of roof falling (roof collapse), land subsidence, and collapse result in a series of secondary disasters, directly threatening production, and life safety . Monitoring and evaluation of the anchoring performance is an important basis to judge the effectiveness of bolts, and hence, to ascertain the safety of the underground coal mine roadways.…”

Stability Control of Deep Coal Roadway under the Pressure Relief Effect of Adjacent Roadway with Large Deformation: A Case Study

“…The bottom boundary of the model is fixed in the vertical direction, while the left and right boundaries fixed in the horizontal direction to eliminate the displacement. Besides, the model adopts the Mohr-Coulomb yield criterion, and the physical parameters of rock stratum are shown in Table 1; the text related to Table 1 and the caption should clearly state the parameters were taken from [18][19][20] and that they represent rock mass properties while considering the effect of cleat networks in the coal seam.…”

Long High-Performance Sustainable Bolt Technology for the Deep Coal Roadway Roof: A Case Study

“…The model adopts the Mohr-Coulomb yield criterion. The physical parameters of rock strata are taken from the Menkeqing coal mine and the adjacent Hulusu coal mine of the same coal field [13,14]. The process of roadway excavation is realized by "Null" command after the model original rock stress calculation is stable.…”

“…Wang thus proposed the principle that the supporting structure should meet the coordination of large deformation of roof. Xie [13,14] discussed the mechanical characteristics and energy dissipation law of different high ratio coal rock structure from the perspective of energy release and dissipation and put forward two roof support principles, successfully applying this to the test roadway. Qin [15] used the method of theoretical analysis and numerical simulation to systematically study the distribution characteristics of the roof bearing structure of the deep soft rock roadway and finally proposed and successfully applied the roof reinforcement scheme of the deep dynamic soft rock roadway.…”