Similar simulation study on the deformation and failure of surrounding rock of a large section chamber group under dynamic loading

To study the effect of loading rate on the progressive damage and failure characteristics of coal, an ultrasonic detector and a camera were used to measure the P-wave velocity and record the failure process of cuboid coal samples in uniaxial compression tests with five loading rates. The mechanical properties, damage process, and failure characteristics of the samples were analysed, and the mechanism of the advancing velocity of the working face in coal failure was discussed. The results show that, as the loading rate increases, the peak strength of the sample generally shows an increasing trend, but the elastic modulus changes irregularly. The sample is more prone to local failure before the peak strength. An increase in the loading rate rapidly promotes damage in the sample and accelerates the transition from internal damage to macroscopic failure, with no obvious effect on the ratio of damage threshold to corresponding peak strength. At low loading rates, the samples mainly experienced static failure; the failure form was spalling, and the failure range was wide. At high loading rates, the samples were prone to dynamic failure in the local area, manifested as the ejection of slabs and debris. A greater loading rate produced smaller and thinner slabs and a greater ejection velocity. Properly increasing the advancing velocity of the working face is conducive to reducing spalling to prevent large-area roof fall, but it may increase the possibility of coal burst in local areas. The results of this study provide a reference for roof control and coal burst disaster prevention on the working face in deep coal mining.

Section: Introductionmentioning

confidence: 99%

Progressive Damage Process and Failure Characteristics of Coal under Uniaxial Compression with Different Loading Rates

Zhu

Luo

et al. 2021

“…Because the roof is not well supported, it is prone to the overall sliding of the overlying strata and impact on the retracement channel, resulting in the coal rock dynamic disaster. erefore, reasonable excavation and support technology is particularly important [3][4][5]. Generally, the layout methods of retracement channels used in coal mines include the preexcavation double retracement channel [6][7][8], pre-excavation single retracement channel [8,9], and no pre-excavation retracement channel [10,11].…”

Section: Introductionmentioning

confidence: 99%

Stability and Control of Retracement Channels in Thin Seam Working Faces with Soft Roof

Qin

Zhang

et al. 2021

To reduce the risk of roof falling and rib spalling during equipment retracement in thin coal seam faces with soft roofs, the 25070 working face of Xuehu Coal Mine was taken as the research object, and theoretical analysis, numerical simulation, and field practice methods were used. Under different space relationships between retracement channels and main roof fracture, the load of hydraulic supports was quantitatively analyzed. The relationship between the working resistance of the hydraulic support and the sinking rotation angle of the immediate roof was analyzed, and a reasonable time for the arrangement of the retracement channel was determined. The sublevel excavation technology and the combined support technology of roof anchor cables and coal rib anchors were proposed. The field application shows that the falling height and rate of movable prop of the hydraulic supports, working resistance of the hydraulic supports, and the roof subsidence all meet the requirements of safety production during the terminal mining period, and the surrounding rock control effect of retracement channel was determined to be good. The safe and efficient mining of the coal mine is ensured, and the research results can provide guidance for similar working faces.

“…e original research of rock burst mainly focuses on its occurrence mechanisms [7], monitoring methods [8,9], early warning [6,10], and control measures [11]. Dozens of rock burst mechanisms have been developed to explain the occurrence of rock burst to a certain extent, including dynamic and static load principle [12], start-up theory [13], energy theory [14], strength theory [15], and butterfly rock burst mechanism [16], and the effect of dynamic load-and stress-induced instability is highly recognized [17,18]. Normally, the monitoring and control of rock burst are carried out separately [19], which are mainly based on the principles of microseism.…”

Section: Introductionmentioning

confidence: 99%

Vibration Behavior during Underground Drilling Based on an Innovative Measurement Method and the Application

Cheng

Zhang

et al. 2021

Pressure relief drilling is one of the most common techniques to reduce the impact of rock burst, but the useful dynamic phenomena in the drilling process are ignored due to the lack of corresponding technical methods. Based on the fact, an innovative measurement method for vibration signals during the drilling construction by pneumatic drill rig is presented in this study. The acquisition and analysis of vibration signals show that the vibration information can reflect the drilling depth, the amplitude of different depth can reflect the pressure, and the vibration events of different depths can reflect the pressure relief effect. The method proposed in the study is of great significance to the supervision of the relief work quantity, the disclosure of the pressure situation, and the evaluation of the pressure relief effect.