scholarly journals Stress Relief and Support for Stability of Deep Mining Roadway with Thick Top Coal in Hujiahe Coal Mine with the Risk of Rock Burst

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Wenjing Liu ◽  
Deyu Qian ◽  
Xingguo Yang ◽  
Sujian Wang ◽  
Jinping Deng ◽  
...  
Keyword(s):  
Rock Burst ◽  
Coal Mine ◽  
Large Diameter ◽  
Stability Control ◽  
Surrounding Rock ◽  
Shaanxi Province ◽  
Pressure Relief ◽  
Working Face ◽  
Deformation Speed ◽  
Plastic Transformation

Rock burst is a typical dynamic disaster in deep underground coal mining. Based on the support problems of the deep roadways in fully mechanized caving face 401111 of Hujiahe Coal Mine suffering from rock burst in Shaanxi Province of China, the failure law and influencing factors of the surrounding rock of the roadway are analyzed. The results show that the deformation of surrounding rock in the roadway shows the characteristics of elastic, plastic transformation, rheology, and expansion. At the same time, it has the typical characteristics of deep roadway, such as the fast deformation speed, long duration, asymmetric deformation, and large loose broken area of surrounding rock. Based on the principle of “strengthening support in shallow zones” and “deep pressure relief in deep zones” in the surrounding rock, the control scheme of surrounding rock in the return roadway of fully mechanized caving working face 401111 is proposed by taking the large diameter pressure relief and deep hole blasting as the main means of pressure relief. The practice shows that the surrounding rock of the return roadway is relatively stable after the implementation of the new scheme, which shows that the design of the new support scheme is reasonable and reliable. It is of great significance for the stability control of surrounding rock of the mining roadway suffering from rock burst.

scholarly journals Study on Microseismic Monitoring, Early Warning, and Comprehensive Prevention of a Rock Burst under Complex Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Ke Ding ◽  
Lianguo Wang ◽  
Mei Yu ◽  
Wenmiao Wang ◽  
Bo Ren
Keyword(s):  
Coal Seam ◽  
Rock Burst ◽  
Large Diameter ◽  
Elastic Strain Energy ◽  
Surrounding Rock ◽  
Control Effect ◽  
Pressure Relief ◽  
Working Face ◽  
Geological Conditions ◽  
Microseismic Events

Rock bursts in coal mines are usually unpredictable. In view of this problem, the energy–frequency relationship and spatial distribution characteristics of microseismic events during the mining of 5305 working face in Xinhe Coal Mine under complex geological conditions were analyzed in this study. Besides, the law and precursors of rock burst occurrence in this working face were discussed. The following research results were obtained. Before the rock burst occurred in 5305 working face, the energy and frequency of microseismic events vary in the following order: “peak-drop-rise-rock burst.” The analysis on spatial characteristics of microseismic events suggests that microseismic events were mainly concentrated at the boundary between the roof and the coal seam or at the hard roof near the coal seam within 0–160 m in front of the working face, and most of the events lay on the goaf side. Moreover, the energy and frequency of microseismic events both decrease in the above region before the rock burst occurred. This “microseismic event absence” phenomenon can be regarded as one of the precursors of rock burst occurrence. In addition, a multilevel antiburst scheme was proposed for the complex conditions: (1) to adopt large-diameter boreholes pressure relief technology and key layer high-level pressure relief technology for adjusting the stress distribution in the surrounding rock of crossheading in front of the working face and dissipating elastic strain energy; (2) to determine the advance speed to be 1.5 m/d for reducing the mining disturbance; (3) to adopt full-section reinforced support of the roadway for enhancing the antiburst capacity of surrounding rock. After the implementation of this scheme, the energy and frequency of microseismic events monitored on-site changed gently, and 5305 working face was safely recovered to the stop line position. The scheme boasts a remarkable rock burst prevention and control effect.

scholarly journals Analysis on Rock Burst Risks and Prevention of a 54 m-Wide Coal Pillar for Roadway Protection in a Fully Mechanized Top-Coal Caving Face

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Zhihua Li ◽  
Ke Yang ◽  
Jianshuai Ji ◽  
Biao Jiao ◽  
Xiaobing Tian
Keyword(s):  
Coal Seam ◽  
Rock Burst ◽  
Influencing Factors ◽  
Abutment Pressure ◽  
Large Diameter ◽  
Coal Pillar ◽  
Distribution Characteristics ◽  
Pressure Relief ◽  
Working Face ◽  
Coal Pillars

A case study based on the 401103 fully mechanized caving face in the Hujiahe Coal Mine was carried out in this research to analyze the rock burst risks in a 54 m-wide coal pillar for roadway protection. Influencing factors of rock burst risks on the working face were analyzed. Stress distribution characteristics on the working face of the wide coal pillar for roadway protection were discussed using FLAC3D numerical simulation software. Spatial distribution characteristics of historical impact events on the working face were also investigated using the microseismic monitoring method. Results show that mining depth, geological structure, outburst proneness of coal strata, roof strata structure, adjacent mining area, and mining influence of the current working face are the main influencing factors of rock burst on the working face. Owing to the collaborative effects of front abutment pressure of the working face and lateral abutment pressure in the goaf, the coal pillar is in the ultimate equilibrium state and microseismic events mainly concentrate in places surrounding the coal pillars. Hence, wide coal pillars become the regions with rock burst risks on the working face. The working face adopts some local prevention technologies, such as pressure relief through presplitting blasting in roof, pressure relief through large-diameter pores in coal seam, coal seam water injection, pressure relief through large-diameter pores at bottom corners, and pressure relief through blasting at bottom corners. Moreover, some regional prevention technologies were proposed for narrow coal pillar for roadway protection, including gob-side entry, layer mining, and fully mechanized top-coal caving face with premining top layer.

scholarly journals Pressure-Relief Mechanism and Application of Large-Diameter Boreholes in Coal Seams with Rockburst Hazard

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhen Hao ◽  
Guangzhong Sun ◽  
Haihang Wei ◽  
Jiayu Liu ◽  
Maolin Tian ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Plastic Zone ◽  
Coal Seam ◽  
Large Diameter ◽  
Engineering Application ◽  
Surrounding Rock ◽  
Pressure Relief ◽  
Effective Measure ◽  
Rockburst Hazard ◽  
Working Face

Drilling of large-diameter boreholes is regarded as an effective measure for rockburst prevention. By investigating the morphological characteristic and evolution of plastic zone in borehole surrounding rock, the pressure-relief mechanism of large-diameter borehole was ascertained, and the engineering application of large-diameter boreholes was assessed in the 13230 working face of Gengcun Coal Mine, Henan Province, China. The results showed that (1) the plastic zone in surrounding rock of borehole appear as circular, elliptical, and butterfly shapes, in which the maximum size of the butterfly wings of the plastic zone is several times larger than the borehole diameter; (2) under certain stress conditions, multiple large-diameter boreholes distributed in coal seam with rockburst risk lead to the generation and coalescence of large-range butterfly-shape plastic zone. They reduce the stress concentration and capacity for storing elastic energy of coal seam, thus reducing the rockburst risk of the coal seam; (3) large-diameter boreholes significantly decrease the stress concentration in front of the 13230 working face and improve the stress environment in the head entry, promoting the safe mining of the working face.

scholarly journals Stability Control of Deep Coal Roadway under the Pressure Relief Effect of Adjacent Roadway with Large Deformation: A Case Study

2021 ◽  
Vol 13 (8) ◽  
pp. 4412
Author(s):  
Houqiang Yang ◽  
Nong Zhang ◽  
Changliang Han ◽  
Changlun Sun ◽  
Guanghui Song ◽  
...  
Keyword(s):  
Large Deformation ◽  
Coal Mine ◽  
High Stress ◽  
Surrounding Rock ◽  
Western China ◽  
Engineering Practice ◽  
Pressure Relief ◽  
Coal Roadway ◽  
And Control ◽  
Relief Effect

High-efficiency maintenance and control of the deep coal roadway surrounding rock stability is a reliable guarantee for sustainable development of a coal mine. However, it is difficult to control the stability of a roadway that locates near a roadway with large deformation. With return air roadway 21201 (RAR 21201) in Hulusu coal mine as the research background, in situ investigation, theoretical analysis, numerical simulation, and engineering practice were carried out to study pressure relief effect on the surrounding rock after the severe deformation of the roadway. Besides, the feasibility of excavating a new roadway near this damaged one by means of pressure relief effect is also discussed. Results showed that after the strong mining roadway suffered huge loose deformation, the space inside shrank so violently that surrounding rock released high stress to a large extent, which formed certain pressure relief effect on the rock. Through excavating a new roadway near this deformed one, the new roadway could obtain a relative low stress environment with the help of the pressure relief effect, which is beneficial for maintenance and control of itself. Equal row spacing double-bearing ring support technology is proposed and carried out. Engineering practice indicates that the new excavated roadway escaped from possible separation fracture in the roof anchoring range, and the surrounding rock deformation of the new roadway is well controlled, which verifies the pressure relief effect mentioned. This paper provides a reference for scientific mining under the condition of deep buried and high stress mining in western China.

scholarly journals Study of the Stability Control of the Rock Surrounding Double-Key Strata Recovery Roadways in Shallow Seams

2019 ◽  
Vol 2019 ◽  
pp. 1-21 ◽  
Author(s):  
Cheng Zhu ◽  
Yong Yuan ◽  
Zhongshun Chen ◽  
Zhiheng Liu ◽  
Chaofeng Yuan
Keyword(s):  
Engineering Application ◽  
Stability Control ◽  
Surrounding Rock ◽  
Control Effect ◽  
Pressure Relief ◽  
Support Design ◽  
Key Strata ◽  
Fracture Development ◽  
Surrounding Rock Control ◽  
The Stability

The stability control of the rock surrounding recovery roadways guarantees the safety of the extraction of equipment. Roof falling and support crushing are prone to occur in double-key strata (DKS) faces in shallow seams during the extraction of equipment. Therefore, this paper focuses on the stability control of the rock surrounding DKS recovery roadways by combining field observations, theoretical analysis, and numerical simulations. First, pressure relief technology, which can effectively release the accumulated rock pressure in the roof, is introduced according to the periodic weighting characteristics of DKS roofs. A reasonable application scope and the applicable conditions for pressure relief technology are given. Considering the influence of the eroded area on the roof structure, two roof mechanics models of DKS are established. The calculation results show that the yield load of the support in the eroded area is low. A scheme for strengthening the support with individual hydraulic props is proposed, and then, the support design of the recovery roadway is improved based on the time effects of fracture development. The width of the recovery roadway and supporting parameters is redesigned according to engineering experience. Finally, constitutive models of the support and compacted rock mass in the gob are developed with FLAC3D software to simulate the failure characteristics of the surrounding rock during pressure relief and equipment extraction. The surrounding rock control effects of two support designs and three extraction schemes are comprehensively evaluated. The results show that the surrounding rock control effect of Scheme 1, which combines improved support design and the bidirectional extraction of equipment, is the best. Engineering application results show that Scheme 1 realizes the safe extraction of equipment. The research results can provide a reference and experience for use in the stability control of rock surrounding recovery roadways in shallow seams.

scholarly journals Study on the Instability Characteristics and Bolt Support in Deep Mining Roadways Based on the Surrounding Rock Stability Index: Example of Pansan Coal Mine

2020 ◽  
Vol 2020 ◽  
pp. 1-16 ◽  
Author(s):  
Jucai Chang ◽  
Kai He ◽  
Zhiqiang Yin ◽  
Wanfeng Li ◽  
Shihui Li ◽  
...  
Keyword(s):  
Coal Mine ◽  
Stability Index ◽  
Surrounding Rock ◽  
Full Length ◽  
Control Effect ◽  
Support Design ◽  
Rock Stability ◽  
Working Face ◽  
The Stability ◽  
Bolt Support

In view of the influence of mining stress on the stability of the surrounding rock of inclined roof mining roadways in deep mines, the surrounding rock stability index is defined and solved based on the rock strength criterion and the stress distribution. The mining roadway of the 17102(3) working face of the Pansan Coal Mine is used as the engineering background and example. The surrounding rock’ stabilities under the conditions of no support and bolt support are analyzed according to the surrounding rock’s stability index and the deformation data. The results show that the areas of low wall and high wall instability are 1.68 m2 and 2.12 m2, respectively, and the low wall is more stable than the high wall; the areas of the roof and floor instability are 0.33 m2 and 0.35 m2, respectively, and the roof and floor are more stable than the two sides. During mining, the area of instability greatly increases at first, then decreases to 0, and reaches a maximum value at the peak of the abutment pressure. The stability of the surrounding rock decreases first and then increases. Compared with the end anchoring bolt support, the full-length anchoring bolt support reduces the area of instability to a greater extent, and the full-length anchoring bolt support effect is better. The surrounding rock in the end anchoring zone and the full-length anchoring zone began to deform significantly at 200 m and 150 m from the working face, respectively. This indicates that the control effect of the full-length anchoring bolt support is better and verifies the rationality of the surrounding rock stability index to describe the instability characteristics. This research method can provide a theoretical reference for analysis of the stability characteristics and support design of different cross-section roadways.

scholarly journals Stress Evolution Law of Surrounding Rock with Gob-Side Entry Retaining by Roof Cutting and Pressure Release in Composite Roof

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yong Zhang ◽  
Huichen Xu ◽  
Peng Song ◽  
Xiaoming Sun ◽  
Manchao He ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Surrounding Rock ◽  
Rock Stress ◽  
Dynamic Adjustment ◽  
Pressure Relief ◽  
Middle Point ◽  
Pressure Release ◽  
Whole Process ◽  
Working Face ◽  
Surrounding Rock Stress

The stress concentration of gob-side entry surrounding rock is a hot topic in coal mining. In this paper, through theoretical analysis and numerical simulation, the pressure relief mechanism of the gob-side entry retaining by roof cutting and pressure release (RCPR) and the spatiotemporal development law of surrounding rock stress of the gob-side entry were analyzed. The studies showed that the gob-side entry retaining by RCPR shortened the length of the lateral cantilever by directional roof cutting, which weakened the stress level of the gob-side entry. In the meantime, the goaf gangues could play a good filling role by using their breaking and swelling characteristics under the action of gangue-blocking supports and further optimized the stress environment along the roadway. Field industrial tests verified that the gob-side entry retaining by RCPR had a significant effect on pressure relief, and the surrounding rock stress and deformation tended to stabilize after about 160 m of lagging working face. Numerical analysis reproduced the whole process of “mining-retention-using” of roof cutting roadway and revealed that surrounding rocks were always in the zone of relative stress reduction during the whole process. The peak value of mining-induced lateral stress was about 10 m away from the middle point of the gob-side entry. The change of surrounding rock stress could be divided into three stages: significant increase, dynamic adjustment, and stable stage. However, during the second mining, the stress connected zone would appear on the leading working face, and the stress concentration in this zone was significant. Based on the above analysis, we concluded that the new technology could be applied to the medium-thickness coal seam in the composite roof.

scholarly journals Deformation Rules for Surrounding Rock in Directional Weakening of End Roofs of Thin Bedrocks and Ultrathick Seams

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Fei Liu ◽  
Zhanguo Ma ◽  
Yongsheng Han ◽  
Zhimin Huang
Keyword(s):  
Abutment Pressure ◽  
Main Roof ◽  
Stability Control ◽  
Surrounding Rock ◽  
Western China ◽  
Resource Exploitation ◽  
Failure Characteristics ◽  
Key Strata ◽  
Working Face ◽  
Geological Conditions

With the deployment of China’s energy strategy in the western regions, complex geological mining conditions such as thin bedrock and ultrathick seams in western China have caused a series of problems such as serious deformation of the surrounding rock at the ends of the working face and the increase in the lead abutment pressure of the roadways; the research on end roof deformation in the resource exploitation in western China has become one of the great demands of the industry. Based on the failure characteristics of rock mass, relying on the actual mining geological conditions of a coal mine in Inner Mongolia, the failure characteristics of the overlying rock strata under the influence of mining were simulated and analyzed using similar material simulation experiment, which intuitively reproduced the failure and deformation processes of the immediate roof, main roof, and key strata and revealed the mechanical mechanism of the directional weakening of the end roof. It is of great significance for the stability control of the surrounding rock at the end of the fully mechanized caving face in the thin bedrocks and ultrathick seams, reducing the abutment pressure of gate roadway and controlling the spontaneous combustion of residual coal in the goaf.

Prevention and Control Technology Research on Rock Burst of Fully Mechanized Caving Faces and Gob-Side Entry

2013 ◽  
Vol 353-356 ◽  
pp. 303-306
Author(s):  
Zhi Chao Tian ◽  
Long Hao Dong ◽  
Min Ma ◽  
Ye Jiao Liu
Keyword(s):  
Rock Burst ◽  
Coal Mine ◽  
Similar Condition ◽  
Economic Benefit ◽  
Prevention And Control ◽  
Scientific Basis ◽  
Surrounding Rock ◽  
Control Technology ◽  
Technology Research ◽  
And Control

According to the actual monitoring data of mining environment and rock burst happening on the 3511 fully-mechanized workface in Anyuan coal mine, the research of the rock burst on the workface and its surrounding rock of gob-side entry is done and the reasonable supporting scheme is determined. The research results are of great guiding importance to the coal mining that has similar condition, provide scientific basis for the control technology of rock burst on the workface and its gob-side entry as well as the reasonable identification of support parameters on the gob-side tunnel, and supply technology protection in order to accelerate the advancing speed of workface. Finally it can produce larger economic benefit.

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