Experimental study on rock-breaking performance of water jets generated by self-rotatory bit and rock failure mechanism

Lu, Yiyu; Xiao, Songqiang; Ge, Zhaolong; Zhou, Zhe; Ling, Yuanfei; Wang, Lei

doi:10.1016/j.powtec.2019.01.078

Cited by 76 publications

(29 citation statements)

References 24 publications

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“…However, the gas occurrence conditions of coal seams in China are relatively complex, and more than 53% of coal seams are soft and low permeability coal seams (Liu, 2014). For most mining areas, the coal seam permeability is 10 À4 -10 À3 mD, which is 3-4 orders of magnitude lower than that in the United States and Australia (Liu and Harpalani, 2013;Lu et al, 2019;Xiao et al, 2018;. This low coal seam permeability results in the low extraction efficiency of CBM.…”

Section: Introductionmentioning

confidence: 95%

Methane displacement characteristic of coal and its pore change in water injection

Chen

Shan

Sun

et al. 2020

Energy Exploration & Exploitation

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Coalbed methane as one type of clean energy has become an important gas resource recently. High-pressure water injection in coal seams is an effective approach for improving gas extraction efficiency, which is determined by the gas displacement characteristic and pore structure of coal. To investigate the gas displacement characteristics in coal and its pore response and influential factors, gas adsorption and water injection experiments were conducted under different conditions. The results show that the gas displacement caused by the water injection undergoes three stages: rapid increase, slow increase, and almost constant. The wetting process in water injection includes three processes: wetting, soaking, and spreading, and the wettability of coking coal is best, followed by lean coal and anthracite. The amount of gas driven by the water increases with increasing water injection pressure, and it is more favorable to increase the injection pressure to improve the gas displacement effect under the relatively low injection pressure. The lower the coal rank, the better the gas displacement effect due to the higher porosity of the coal, and the longer the early gas displacement stage. The high adsorption equilibrium pressure can improve the gas displacement effect; for the relatively high adsorption equilibrium pressure, the gas displacement effect is better. After water injection in coal, the large fractures and pores dramatically increase in size, especially for the low metamorphic coals coking coal, contributing to the majority of the increase in porosity. The results of this study can provide a theoretical foundation for the wide application of water injection technology for efficient gas drainage in coal mines.

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Section: Introductionmentioning

confidence: 95%

Methane displacement characteristic of coal and its pore change in water injection

Chen

Shan

Sun

et al. 2020

Energy Exploration & Exploitation

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“…Extraction of CBM not only increases energy supply, but can also reduce greenhouse gas emissions and the occurrence of gas disasters. China is rich in CBM resources, ranking third in the world [1], but is highly dependent on natural gas imports. In 2018, China became the world's largest importer of natural gas, with an import volume of 125.4 billion m 3 [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Structural Optimization of Slotting Nozzle Used to Improve Coal-Seam Permeability

Zhong

Zhang

et al. 2020

Applied Sciences

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Slotting directional hydraulic fracturing is a new method for improving permeability of a coal seam in underground coal mines that can solve problems related to non-uniform permeability enhancement in the seam. A slotting nozzle is the key to this technology: its performance determines the length and stability of the slotted hole. In this study, computational fluid dynamics was used to study the effects of stable segment length L, convergent angle θ, and straight segment length l on the performance of slotting nozzles. The results showed that the order of parameters affecting nozzle performance is: θ > L > l. When the total length of the slotting nozzle was fixed, the dynamic pressure gradually decreased with an increase of L and the rate of decrease slowed down. With an increase of θ, dynamic pressure increased quadratically and the rate of change gradually decreased. With an increase of l, the dynamic pressure decreased quadratically and the rate of change gradually increased. A slotting nozzle (L = 0 mm, θ = 30°, l = 9 mm) was manufactured and measurements of flow coefficient, water jet morphology, and a slotting experiment were carried out. The experimental results showed that the flow coefficient, water jet convergence, and slotting depth of the optimized slotting nozzle were obviously higher than those of the original design, which proved the validity of using this numerical method to optimize the slotting nozzle structure.

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“…been investigated and tested [4]- [7]. In 1965, the British Farmer, I. W. et al studied the impact erosion effects on the non-igneous rock fracture by pure water jets experimentally and analyzed the rock-breaking mechanism [8].…”

Section: Introductionmentioning

confidence: 99%

Positioning and Sequence Planning of Drilling Boreholes in Hard Rock Roadway

Cui

Liu

et al. 2020

IEEE Access

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The safety and efficiency of hard rock roadway excavation are the two sides of a coin limiting the implementation of roadway construction. It is an effective way to improve the performance in hard rock tunneling to effectively release the internal stress in rock mass by arranging pre-prepared boreholes in rock section. In order to improve the rock breaking performance and tunneling efficiency, we analyze the borehole positioning accuracy and explore boreholes sequence planning problem in hard rock excavation simulatively and experimentally. The kinematics model of drilling mechanism is established based on the D-H method. RBF neural network algorithm is adopted to accurately position borehole. The results show that accuracy of simulated borehole positioning is controlled at 1.5% while the accuracy is 5.6% of experiment. The Ant Colony Algorithm (ACA) is employed to optimize the sequence planning of drilling boreholes with the optimization goals of minimum moving distance and minimum swing angle separately. Simulation results show that rock-drilling with the minimum swing angle produces smaller positioning deviation and higher efficiency, which is a practical automatic roadway borehole drilling method. INDEX TERMS Borehole positioning, RBF neural network, sequence planning, ant colony algorithm (ACA).

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Experimental study on rock-breaking performance of water jets generated by self-rotatory bit and rock failure mechanism

Cited by 76 publications

References 24 publications

Methane displacement characteristic of coal and its pore change in water injection

Methane displacement characteristic of coal and its pore change in water injection

Structural Optimization of Slotting Nozzle Used to Improve Coal-Seam Permeability

Positioning and Sequence Planning of Drilling Boreholes in Hard Rock Roadway

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