Non-destructive testing and pre-warning analysis on the quality of bolt support in deep roadways of mining districts

Zhang, Houquan; Miao, Xiaoyu; Zhang, Guimin; Yu, Wu; Chen, Yanlong

doi:10.1016/j.ijmst.2017.06.028

Cited by 34 publications

(8 citation statements)

References 5 publications

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“…In recent years, most coal mining has entered the deep mining stage. In the new geological situation, the existing single roadway support method cannot meet the current requirements for maintaining the stability of the roadway [3]. Therefore, in view of the problems existing in roadway support, the method of combined support has been studied.…”

Section: Introductionmentioning

confidence: 99%

The use of surrounding rock loosening circle theory combined with elastic-plastic mechanics calculation method and depth learning in roadway support

et al. 2020

PLoS ONE

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The objective is to study the design method of roadway support and provide technical support for coal mining and other mining methods that need deep roadway excavation. Through literature review, the occurrence, development mechanism and influencing factors of surrounding loose rock zones of roadways are analyzed. A method of detecting is selected according to the characteristics of surrounding rock loosening. Knowledge of elastoplastic mechanics is used to theoretically study the failure mechanism of surrounding rock in deep re-mining roadways. Based on the artificial neural network prediction model (ANN), the surrounding rock is classified and a support network model of the decision system is constructed. After the design of roadway support, a sharp change of vault subsidence normally occurs within about 7 days after excavation, and the total subsidence is 14 mm. In the following month, deformation is slow, subsidence is small, and it is basically stable after one month. The curve of the vault subsidence rate shows that the vault subsidence rate is less than or equal to 1mm/d after 7 days. The convergence rate is also less than 1 mm/d after 7 days. There are two cave mouths AB and CD, and the convergence value of AB is 6.47mm, CD is 10.26mm: CD is slightly larger than AB, and it is close to stable one month later. It is essentially consistent with the time of vault settlement and stability, and the amount of deformation is approximately the same. This shows that, with the advance of the working face, the displacement of the surrounding rock in the section away from the working face will gradually decrease and the surrounding rock will be stable. The stability time of surrounding rock displacement of the portal section is the same as that of vault subsidence under the initial support, and the amount of deformation is approximately the same, indicating that the support parameters and construction methods are reasonable.

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Section: Introductionmentioning

confidence: 99%

The use of surrounding rock loosening circle theory combined with elastic-plastic mechanics calculation method and depth learning in roadway support

et al. 2020

PLoS ONE

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“…When the tunnel is close to the stoppage line and the coal pillar of retaining lane is insufficiently reserved, the abutment pressure and rock stratum are broken. The occurrence of Mining pressure will cause stress disturbance to the tunnel in front of the working face, leading to a large deformation of the tunnel [Li et al(2012), Meng et al (2016), Wang et al (2008), Zhang et al (2012), Zhang et al (2016), Zhang et al (2011), Jiang et al (2016), Zhang et al (2017), Xu et al (2019)]. Therefore, it is especially important to control the range of dynamic pressure.…”

Section: Introductionmentioning

confidence: 99%

Study on Mining Pressure Control of Deep Coal Seam——Based on Artificial Fault Technology

Xu¹,

Gao²,

He³

et al. 2021

Preprint

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Based on the pressure transfer principle and stress distribution characteristics around a fault, introducing artificial fault technology to control the propagation of abutment pressure, and a mechanical model of abutment pressure under the influence of artificial fault was established. This new mechanical model can well fit the distribution law of mining stress after roof cutting. The pressure transfer mechanism of prefabrication support of rock blasting was analyzed, and the transfer trend of pressure and the mining stress of rock top was determined. It is of great significance to guide the implementation of the pressure relief work at the top of the stope. The study shows that the total energy of the system is conserved, the integrity of rock layer is destroyed by blasting, and the deformation and damage of pressure relief zone absorb a large amount of energy. Thus, the accumulated strain energy of abutment pressure region is released, and the influencing range of abutment pressure is reduced. As the horizontal distance from the cutting surface is farther away from the working surface, the smaller the stress difference on both sides of the cutting top, the less obvious the blocking effect of mining pressure. When the cutting point is closer to the working surface, the higher the peak value of abutment pressure due to the superposition of peripheral stress concentration caused by the cutting and peak of abutment pressure caused by mining. Then, the numerical simulation analysis was carried out, the results show that the technology of forming artificial fault by cutting the top can cut off the influence range of the mining pressure. It can effectively control the deformation of dynamic pressure tunnl. Finally, a practice of rock blasting pressure relief engineering was carried out, and the influencing range of abutment pressure of working face before blasting pressure reduction was reduced by 1/3 compared with that before the pressure relief.

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“…Wang, et al (2020) utilized ABAQUS to create a finite element model under the original support design, suggested a zoned bolt-grouting reinforcement technology, and numerically tested its support impact. Using self-developed random non-destructive testing methodologies and equipment, Zhang, et al (2017) suggested an early warning system for the integrity of the roadway envelope based on anchor axial load detection.…”

Section: Introductionmentioning

confidence: 99%

Failure Analysis of Intersections of Large-Scale Variable Cross-Section Roadways in Deep Soft Rock and Study of Integrated Control Technology of Bolting and Grouting

Xie¹,

Wu²,

Chen³

et al. 2021

Preprint

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In deep underground mining, achieving stable support for roadways along with long service life is critical and the complex geological environment at such depths frequently presents a major challenge. Owing to the coupling action of multiple factors such as deep high stress, adjacent faults, cross-layer design, weak lithology, broken surrounding rock, variable cross-sections, wide sections up to 9.9 m, and clusters of nearby chambers, there was severe deformation and breakdown in the No. 10 intersection of the roadway of large-scale variable cross-section at the − 760 m level in the Nanfeng working area of the Wuyang Coal Mine. As there are insufficient examples in engineering methods pertaining to the geological environment described above, the numerical calculation model was oversimplified and support theory underdeveloped; therefore, it is imperative to develop an effective support system for the stability and sustenance of deep roadways. In this study, a quantitative analysis of the geological environment of the roadway through field observations, borehole peeking, and ground stress testing is carried out to establish the FLAC 3D variable cross-section crossing roadway model. This model is combined with the strain softening constitutive (surrounding rock) and Mohr-Coulomb constitutive (other deep rock formations) models to construct a compression arch mechanical model for deep soft rock, based on the quadratic parabolic Mohr criterion. An integrated control technology of bolting and grouting that is mainly composed of a high-strength hollow grouting cable bolt equipped with modified cement grouting materials and a high-elongation cable bolt is developed by analyzing the strengthening properties of the surrounding rock before and after bolting, based on the Heok-Brown criterion. As a result of on-site practice, the following conclusions are drawn: (1) The plastic zone of the roof of the cross roadway is approximately 6 m deep in this environment, the tectonic stress is nearly 30 MPa, and the surrounding rock is severely fractured. (2) The deformation of the roadway progressively increases from small to large cross-sections, almost doubling at the largest cross-section. The plastic zone is concentrated at the top plate and shoulder and decreases progressively from the two sides to the bottom corner. The range of stress concentration at the sides of the intersection roadway close to the passageway is wider and higher. (3) The 7 m-thick reinforced compression arch constructed under the strengthening support scheme has a bearing capacity enhanced by 1.8 to 2.3 times and increase in thickness of the bearing structure by 1.76 times as compared to the original scheme. (4) The increase in the mechanical parameters c and φ of the surrounding rock after anchoring causes a significant increase in σc and σt; the pulling force of the cable bolt beneath the new grouting material is more than twice that of ordinary cement grout, and according to the test, the supporting stress field shows that the 7.24 m surrounding rock is compacted and strengthened in addition to providing a strong foundation for the bolt (cable). On-site monitoring shows that the 60-day convergence is less than 30 mm, indicating that the stability control of the roadway is successful.

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Non-destructive testing and pre-warning analysis on the quality of bolt support in deep roadways of mining districts

Cited by 34 publications

References 5 publications

The use of surrounding rock loosening circle theory combined with elastic-plastic mechanics calculation method and depth learning in roadway support

The use of surrounding rock loosening circle theory combined with elastic-plastic mechanics calculation method and depth learning in roadway support

Study on Mining Pressure Control of Deep Coal Seam——Based on Artificial Fault Technology

Failure Analysis of Intersections of Large-Scale Variable Cross-Section Roadways in Deep Soft Rock and Study of Integrated Control Technology of Bolting and Grouting

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