Deep-hole pre-split blasting mechanism and its application for controlled roof caving in shallow depth seams

Wang, Fangtian; Tu, Shihao; Yuan, Yue; Feng, Yufeng; Chen, Fang; Tu, Hongsheng

doi:10.1016/j.ijrmms.2013.08.026

Cited by 112 publications

(63 citation statements)

References 5 publications

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“…However, use of explosives incorporates a lot of issues that need to be properly addressed for the desired result. In the case of deep mining, the difficulties in charging, sealing and controlling misfire are critical [3,4] as those come up with various environmental issues as, ground excitations, generation of dust, air blast, fly rock and back-break [5][6][7][8][9].…”

Section: Explosive Blastingmentioning

confidence: 99%

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

2016

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Global energy and material consumption are expected to rise in exponential proportions during the next few decades, generating huge demands for deep earth energy (oil/gas) recovery and mineral processing. Under such circumstances, the continuation of existing methods in rock fragmentation in such applications is questionable due to the proven adverse environmental impacts associated with them. In this regard; the possibility of using more environmentally friendly options as Soundless Chemical Demolition Agents (SCDAs) play a vital role in replacing harmful conventional rock fragmentation techniques for gas; oil and mineral recovery. This study reviews up to date research on soundless cracking demolition agent (SCDA) application on rock fracturing including its limitations and strengths, possible applications in the petroleum industry and the possibility of using existing rock fragmentation models for SCDA-based rock fragmentation; also known as fracking. Though the expansive properties of SCDAs are currently used in some demolition works, the poor usage guidelines available reflect the insufficient research carried out on its material's behavior. SCDA is a cementitious powdery substance with quicklime (CaO) as its primary ingredient that expands upon contact with water; which results in a huge expansive pressure if this CaO hydration reaction occurs in a confined condition. So, the mechanism can be used for rock fragmentation by injecting the SCDA into boreholes of a rock mass; where the resulting expansive pressure is sufficient to create an effective fracture network in the confined rock mass around the borehole. This expansive pressure development, however, dependent on many factors, where formation water content creates a negative influence on this due to required greater degree of hydration under greater water contents and temperature creates a positive influence by accelerating the reaction. Having a precise understanding of the fracture propagation mechanisms when using SCDA is important due to the formation of complex fracture networks in rocks. Several models can be found in the literature based on the tangential and radial stresses acting on a rock mass surrounding an SCDA charged borehole. Those fracture models with quasi-static fracturing mechanism that occurs in Mode I type tensile failure show compatibility with SCDA fracturing mechanisms. The effect of borehole diameter, spacing and the arrangement on expansive pressure generation and corresponding fracture network generation is important in the SCDA fracturing process and effective handling of them would pave the way to creating an optimum fracture network in a targeted rock formation. SCDA has many potential applications in unconventional gas and oil recovery and in-situ mining in mineral processing. However, effective utilization of SCDA in such application needs much extensive research on the performance of SCDA with respect to its potential applications, particularly when considering unique issues arising in using SCDA in different ...

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Section: Explosive Blastingmentioning

confidence: 99%

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

2016

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“…The cycle distance of blasthole (ΔL) is 14 m to prevent LARW. [17,20] and Simulation Plans LS-DYNA is applied to simulate rock blasting, which is explicit dynamic analysis software. A numerical model for shallow-hole blasting is established based on ALE and fluid-structure interaction method.…”

Section: Field Practice and Field Measurementmentioning

confidence: 99%

“…Main technologies are deep-hole and shallow-hole blasting, water injection for softening rock mass, hydraulic fracture to weaken rock mass, decorating unloading groove or pressure relief hole, and other technologies which can transfer stress. Many projects show that deep-hole blasting technology is a frequent way to relief roof pressure [15][16][17]. At present, the deep-hole pre-splitting blasting to relief roof pressure is undertaken in the roadways or in the panel, and blasting parameters are mostly accepted by adopting numerical and laboratory physical experiments.…”

Section: Introductionmentioning

confidence: 99%

An Innovative Approach for Gob-Side Entry Retaining With Thick and Hard Roof: A Case Study

Zhang¹,

Liu²,

Bai

et al. 2018

Teh. vjesn.

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An innovative roadway layout in a Chinese colliery based on gob-side entry retaining (GER) with thick and hard roof (THR) was introduced. Suspended roof is left with a large area in GER with THR, which leads to large area roof weighting (LARW). LARW for GER with THR and mechanism of shallow-hole blasting to force roof caving in GER were expounded. Key parameters of shallow-hole blasting to force roof caving are proposed. LS-DYNA3D was used to validate the rationality of those key parameters, and UDEC was used to discuss and validate shallow-hole blasting to force roof-caving effect by contrast to the model without blasting and the model with shallow-hole blasting. Moreover, shallow-hole blasting technology to force roof caving for GER with THR was carried out in the Chinese colliery as a case study. Field test indicates that shallow-hole blasting technology effectively controls ground deformation of GER with THR and prevents LARW.

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“…In shallow-hole blasting, the detonation of explosives creates shallow cracks in the hanging wall and tensile stress then arise from these cracks during bending induce hanging wall fracture. In contrast, DHB directly uses explosion to fracture hanging wall and reduce the energy it accumulates [39,40]. Given the total thickness of the hanging wall-1 and hanging wall-2 over the 43# seam was 64.1 m, the blasting holes should be longer than 5 …”

Section: Mechanism Of Pressure Relief By Dhbmentioning

confidence: 99%

“…Therefore, the effective damage zone around blasting holes normally refers to the crushed zone and the fractured zone together. The radii of the two zones can be calculated using the following equations [40][41][42]:…”

Section: Theoretical Analysis Of Dhbmentioning

confidence: 99%

Hanging Wall Pressure Relief Mechanism of Horizontal Section Top-Coal Caving Face and Its Application—A Case Study of the Urumqi Coalfield, China

Guo

Wang

et al. 2017

Energies

Self Cite

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Abundant steeply-dipping thick coal seams (SDTCS) have been found in Xinjiang, China, and they are mined largely by the horizontal section top-coal caving (HSTCC) method. The hanging wall of the HSTCC face is nearly vertical and does not fracture easily after the underlying coal is extracted. As a result, stress tends to concentrate in the hanging wall of the lower-section working face (LSWF) and then induce dynamic disasters. In this study, a mechanical model of a HSTCC face's hanging wall in steeply-dipping seams was constructed to study the characteristics of hanging wall deformation. The mechanism of hanging wall pressure relief by deep-hole blasting (DHB) was analyzed and the effectiveness of DHB was investigated by simulation using the LS-DYNA software. Based on these studies, parameters relevant to pressure relief by DHB were determined and then DHB was applied to the 4301 working face in the Jiangou coal mine. The results show that the average pressure of measured at the 4301 working face decreased about 34% from those at the 4501 face where the hanging wall was not blasted. Accidents related to dynamic rock pressure, such as support crushing and large-scale rib fall, did not occur at the 4301 working face throughout the mining process. Additionally, in order to constrain the surface "V"-shaped collapsed grooves induced by repeated mining of HSTCC faces and prevent the subsequent failure of the surrounding rock on the sides of the collapsed grooves, loess was used to fill in the grooves to provide constraint and dynamic control on the surrounding rock. The two complementary technologies proposed in this study provide a guide on how to control hanging wall of SDTCS in similar conditions.

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Deep-hole pre-split blasting mechanism and its application for controlled roof caving in shallow depth seams

Cited by 112 publications

References 5 publications

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

An Innovative Approach for Gob-Side Entry Retaining With Thick and Hard Roof: A Case Study

Hanging Wall Pressure Relief Mechanism of Horizontal Section Top-Coal Caving Face and Its Application—A Case Study of the Urumqi Coalfield, China

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