• Computers and Concrete
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• 제25권2호
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• pp.145-154
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• 2020

For the influence of the propagation law of stress wave at the coal-rock interface during the pre-blasting of the top coal in top coal mining, the ANSYS-LS/DYNA fluid-solid coupling algorithm was used to numerical calculation and the life-death element method was used to simulate the propagation of explosion cracks. The equation of the crushing zone and the fracturing zone were derived. The results were calculated and showed that the crushing radius is 14.6 cm and the fracturing radius is 35.8 cm. With the increase of the angles between the borehole and the coal-rock interface, the vibration velocity of the coal particles and the rock particles at the interface decreases gradually, and the transmission coefficient of the stress wave from the coal mass into the rock mass decreases gradually. When the angle between the borehole and the coal-rock interface is 0°, the overall crushing degree is about 11% and up to the largest. With the increase of the distance from the charge to the coal-rock interface, the stress wave transmission coefficient and the crushing degree of the coal-rock are gradually decreased. At the distance of 50 cm, the crushing degree of the coal-rock reached the maximum of approximately 12.3%.

• Geomechanics and Engineering
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• 제11권3호
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• pp.345-359
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• 2016

In order to investigate the influence of the interfacial angel on failure characteristics and mechanism of combined coal-rock mass, 35 uniaxial/biaxial compressive simulation tests with 5 different interfacial angels of combined coal-rock samples were conducted by PFC2D software. The following conclusions are drawn: (1) The compressive strength and cohesion decrease with the increase of interfacial angle, which is defined as the angle between structure plane and the exterior normal of maximum principal plane, while the changes of elastic modulus and internal friction angle are not obvious; (2) The impact energy index $K_E$ decreases with the increase of interfacial angle, and the slip failure of the interface can be predicted based on whether the number of acoustic emission (AE) hits has multiple peaks or not; (3) There are four typical failure patterns for combined coal-rock samples including I (V-shaped shear failure of coal), II (single-fracture shear failure of coal), III (shear failure of rock and coal), and IV (slip rupture of interface); and (4) A positive correlation between interfacial angle and interface effect is shown obviously, and the interfacial angle can be divided into weak-influencing scope ($0-15^{\circ}$), moderate-influencing scope ($15-45^{\circ}$), and strong-influencing scope (> $45^{\circ}$), respectively. However, the confining pressure has a certain constraint effect on the interface effect.

• 터널과지하공간
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• 제31권6호
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• pp.623-646
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• 2021

국내외적으로 전기화의 가속으로 인해 전력수요가 급증됨에 따라, 석탄화력발전소의 수요가 늘어나고 있다. 석탄화력발전소는 경제적으로 많은 이점이 있지만, 대기오염물질 증가, 발전회의 매립 처분에 의한 오염 유발 가능성 등의 환경적인 문제를 수반하고 있다. 특히, 발전부산물인 발전회의 경우에는 재활용률이 70%에 그치고 있으며, 나머지는 전량 매립되고 있다. 본 연구에서는 발전회의 재활용률을 증대시키고 지하에 위치하는 폐광산의 지반 안정성을 확보하기 위하여, 발전회를 폐광산 채움재로 이용하여 지하 폐광산의 채굴 공동을 충전하는 방안에 대한 기초연구를 수행하였다. 암반과 폐광산 채움재의 접합부에서 상호작용에 의한 충전 및 지반보강 효과를 분석하기 위하여, 다양한 거칠기를 갖는 절리면 모사 시료를 제작하여 접합강도 시험과 직접 전단시험을 수행하고 이에 대한 통계분석을 수행하여 절리면의 거칠기와 재령일에 따른 접합 및 전단거동 특성을 규명하였다. 또한 접합부 거동특성이 전산해석 기법을 이용한 지반안정성 분석에 미치는 영향을 검토하기 위하여 지하광산을 모델링하고 접합부 유무에 따른 거동특성을 비교하였다.

• Geomechanics and Engineering
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• 제24권1호
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• pp.81-89
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• 2021

Uniaxial compression tests were conducted on sandstone-CGFB composite samples with different interface angles, and their strength, acoustic emission (AE), and failure characteristics were investigated. Three macro-failure patterns were identified: the splitting failure accompanied by local spalling failure in CGFB (Type-I), the mixed failure with small sliding failure along with the interface and Type-I failure (Type-II), and the sliding failure along with the interface (Type-III). With an increase of interface angle β measured horizontally, the macro-failure pattern changed from Type-I to Type-II, and then to Type-III, and the uniaxial compressive strength and elastic modulus generally decreased. Due to the small sliding failure along with the interface in the composite sample with β of 45°, AE events underwent fluctuations in peak values at the later post-peak failure stage. The composite samples with β of 60° occurred Type-III failure before the completion of initial compaction stage, and the post-peak stress-time curve initially exhibited a slow decrease, followed by a steep linear drop with peaks in AE events.