Pressure-relief and permeability-increase technology of high liquid–solid coupling blast and its application

Zhou, Hao; Chao, Zhou; Lin, Baiquan; Pang, Yuan; Li, Ziwen

doi:10.1016/j.ijmst.2013.12.008

Cited by 25 publications

(6 citation statements)

References 4 publications

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“…Because the effective stress concentration range of the holes was 5 times the diameter, the distance between the auxiliary holes and the predrilled fracturing holes was set as 170 mm. To avoid the effect of a boundary and rock size on rock breaking, the rock bottom and sides were all set as noreflection boundaries [29,30]. e rock comprises 381518 particles with a uniform distribution, and the particle size was equal to 1.0 mm.…”

Section: Geometric Model and Boundariesmentioning

confidence: 99%

Numerical Investigation on Rock‐Fracturing Mechanism by Using Splitter under Hole Assistance

Liu

Guo

2019

Shock and Vibration

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In this work, a numerical model of rock breaking under hole assistance was established based on the finite element method (FEM) coupling with smoothed particle hydrodynamics (SPH) to reveal rock-breaking mechanisms and analyze the reasons for crack formation and propagation under hole assistance. In addition, the numerical model was verified by experiment with and without a hole, and the simulation results are basically consistent with the experimental results in rock breaking. During the process of rock fracturing, the hydraulic splitter was first inserted into the predrilling hole, and then the wedges were pushed into the rock under the action of the hydraulic pressure. In this process, the splitter wedge was separated from the two sides, and the transverse bursting force was transmitted to the rock. Finally, the main fracture formed and the rock mass broke due to the bursting force. The results show that the cracks propagate along the approximately straight lines OO1 (the distance between the auxiliary holes and the left predrilled fracturing hole) and OO2 (the distance between the auxiliary holes and the right predrilled fracturing hole) before extending to the auxiliary hole which is unlike the crack propagation in rock without auxiliary holes, and the crack propagating direction gradually approaches horizontally and is vertical to the side after passing through the auxiliary holes. Moreover, when the auxiliary holes are located at the prefabricated angles α = 40° and 45°, the crack propagation can be well induced and the cracks pass through the auxiliary holes. However, at α = 50°, the auxiliary holes can no longer well induce the crack propagation in the process of rock breaking; however, the fracturing pressure is still less than that with no auxiliary holes, indicating that the auxiliary holes play a positive role in guiding rock breaking.

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Section: Geometric Model and Boundariesmentioning

confidence: 99%

Numerical Investigation on Rock‐Fracturing Mechanism by Using Splitter under Hole Assistance

Liu

Guo

2019

Shock and Vibration

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“…12 At present, methods of coal seam permeability enhancement include N 2 injection, deep hole presplitting blasting, 13 hydraulic fracturing, 14 hydraulic flushing, 15,16 hydraulic slotting, and other methods. [17][18][19][20][21][22] The permeability has shown a trend of increasing sharply, slightly decrease, and then stable at a constant value after injecting N 2 in CO 2 -rich low permeable seam. 23 Deep hole presplitting blasting measures have limited application due to its complex technology and high risks.…”

Section: Introductionmentioning

confidence: 99%

A new cross‐borehole hydraulic caving technique in the coal seam with a soft layer for preventing coal and gas outbursts during coal roadway excavation

Qin

Wei

Lou

et al. 2020

Energy Science & Engineering

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Predrainage of gas by cross‐boreholes is an important method to prevent coal and gas outbursts in the process of a coal roadway excavation. Limitations of technologies and poor effects of preventing coal and gas outbursts occur in the coal seam with a soft layer. In this study, a new hydraulic caving technology for cross‐boreholes has been proposed to solve this problem. A CT equipment was used to observe the development of coal fissures around cross‐boreholes in the coal seam with a soft layer. The plastic zone range and permeability distribution of ordinary hydraulic slotting technologies and the new hydraulic caving technology also were compared by numerical simulation. The field test of hydraulic caving was taken in the Xuehu Mine (China). The results show that the fracture development degree of soft coal is greater than that of hard coal at the same distance from cross‐boreholes. The fracture development degree in the plastic zone is greater than that in the elastic zone. The hydraulic caving technique can achieve the same effect as the ordinary hydraulic slotting with less workload. The mass of coal discharged from a cross‐borehole was 1.15 t/m and the average methane concentration of single drainage borehole increased by 1.09‐4.1 times, and the average methane extraction amount of single drainage borehole increased by 6.06 times. Elimination of coal and gas outburst had been completed after 110 days of extraction in the area of hydraulic caving, and Q and S values are lower than the critical value during roadway excavation. It is conclusion that hydraulic caving technique can effectively improve the permeability and rapidly eliminate coal and gas outburst in the coal seam with a soft layer.

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“…[5,6]. The tendency in coal mining has been to develop deeper underground, where coal seams have the "three high and two low" characteristic; namely, high geostress, high gas content, high gas pressure, low strength and low permeability [7,8]. The coal seam permeability is less than 0.1 md in many mining areas, which has led to long gas drainage cycles, low gas drainage efficiencies, high material losses and indirect delays in coal seam mining progress and has brought about great economic losses for the coal mining industry [9,10].…”

Section: Introductionmentioning

confidence: 99%

A Mechanical Model of Gas Drainage Borehole Clogging under Confining Pressure and Its Application

Wang

2018

Energies

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Drilling in a coal seam that has gas and coal outburst activities is closely related to the discharge of drill cuttings into a borehole. Due to the low effectiveness of slagging, there is a risk that the drilling equipment will be lost if the borehole contains too many drill cuttings, especially when drilling in soft coal seams that suffer from borehole deformation and instability problems. In order to investigate the mechanisms underlying clogged boreholes, a mechanical model is established that considers the confining pressure pi that surrounds a borehole. The characteristics of clogged boreholes, which are affected by parameters such as the clogging segment’s length L, the drilling angle θ and confining pressure pi, were analyzed. The results show that the dredging pressure has nearly exponential growth as the clogging segment’s length L increases and the gravity of the clogging segment reduces the demand for dredging pressure, especially in upward drilling. In downward drilling, the blowing-through pressure increases as the absolute value of the drilling angle increases and will reach a maximum value when the drilling angle θD is in the range of −π/2~0. At the same time, the borehole’s confining pressure pi is the dominant factor in borehole clogging. Meanwhile, boreholes with a high confining pressure pi, especially in soft coal seams and coal seams with a coal outburst, constitute a significant risk. Finally, an actual drilling field construction was evaluated and optimized by applying the clogging segment mechanical model. The results show that the drilling depth was improved by 18.5% on average, and the drilling efficiency was improved by 39.7%, in comparison to drilling activities without optimization.

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Pressure-relief and permeability-increase technology of high liquid–solid coupling blast and its application

Cited by 25 publications

References 4 publications

Numerical Investigation on Rock‐Fracturing Mechanism by Using Splitter under Hole Assistance

Numerical Investigation on Rock‐Fracturing Mechanism by Using Splitter under Hole Assistance

A new cross‐borehole hydraulic caving technique in the coal seam with a soft layer for preventing coal and gas outbursts during coal roadway excavation

A Mechanical Model of Gas Drainage Borehole Clogging under Confining Pressure and Its Application

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