scholarly journals Analysis of Strata Behavior Process Characteristics of Gob-Side Entry Retaining with Roof Cutting and Pressure Releasing Based on Composite Roof Structure

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Manchao He ◽  
Xingen Ma ◽  
Bin Yu
Keyword(s):  
Mechanical Analysis ◽  
Theoretical Research ◽  
Support Design ◽  
Process Characteristics ◽  
Roof Structure ◽  
Weak Interlayer ◽  
Roadway Support ◽  
Degree Equation ◽  
Roadway Deformation ◽  
Working Resistance

In order to explore the characteristics of rock pressure distribution with roof cutting and pressure releasing under different composite roof structures and optimize the support design of entry retaining, the mechanical analysis and numerical simulation are used to analyze the structure characteristics of composite roof and the effect of roof cutting under composite roof in this paper. Besides, taking the 8304 working face of Tashan Coal Mine as an example, the results of theoretical research are verified by field-monitoring data of hydraulic supports, working resistance, and roadway deformation. The results show that the weak interlayer in the composite roof is easily damaged under the external force and the distribution of the layer has a key effect on the roof characteristics. When the weak interlayer is located at the middle of the roof cutting layer range, the demand of the roadway support strength is the highest; when the weak interlayer is located at the top of the roof cutting layer range, the demand of the roadway support strength is the lowest. Furthermore, with the increase of the height of the weak interlayer in the roof cutting layer range, the stress concentration peak of the coal wall side decreases first and then rises, then descends again, and the trend can be fitted by the curve of a three-degree equation.

scholarly journals Study on the Influence of Anchorage Length and Pretension on the Working Resistance of Rock Bolt Based on its Tensile Characteristics

2021 ◽  
Author(s):  
Jucai Chang ◽  
Kai He ◽  
Dongdong Pang ◽  
Dong Li ◽  
Chuanming Li ◽  
...  
Keyword(s):  
High Strength ◽  
Rock Bolt ◽  
Support Design ◽  
Anchorage Length ◽  
High Strength Bolt ◽  
Working Face ◽  
Key Factor ◽  
Roadway Support ◽  
Working Resistance ◽  
Surrounding Rock Deformation

Abstract In coal mining roadway support design, the working resistance of the rock bolt is the key factor affecting its support effect. Effective improvement of the working resistance is of great significance to roadway support. Based on the rock bolt’s tensile characteristics and the mining roadway surrounding rock deformation, a mechanical model for calculating the working resistance of the rock bolt is established and solved. Taking the mining roadway of the 17102 (3) working face at the Panji 3# Well Coal Mine of China as a research object, with a quadrilateral section roadway, the influence of pretension and anchorage length on the working resistance of high-strength and ordinary rock bolts in the middle and corner of the roadway is studied. The results show that when the bolt is in the elastic stage, increasing the pretension and anchorage length can effectively improve the working resistance. When the bolt is in the yield and strain-strengthening stages, increasing the pretension and anchorage length cannot effectively improve the working resistance. The influence of pretension and anchorage length on the ordinary and high-strength bolts is similar. The ordinary bolt’s working resistance is approximately 25 kN less than that of the high-strength bolt. When pretension and anchorage length are considered separately, the best pretensions of the high-strength bolt in the middle of the roadway side and the roadway corner are 41.55 and 104.26 kN, respectively, and the best anchorage lengths are 1.54 and 2.12 m, respectively. The best anchorage length of the ordinary bolt is the same as that of the high-strength bolt, and the best pretension for the ordinary bolt in the middle of the roadway side and at the roadway corner is 33.51 and 85.12 kN, respectively. The research results can provide a theoretical basis for supporting the design of quadrilateral mining roadways.

scholarly journals Influence of anchorage length and pretension on the working resistance of rock bolt based on its tensile characteristics

2021 ◽  
Author(s):  
Jucai Chang ◽  
Kai He ◽  
Dongdong Pang ◽  
Dong Li ◽  
Chuanming Li ◽  
...  
Keyword(s):  
High Strength ◽  
Rock Bolt ◽  
Support Design ◽  
Anchorage Length ◽  
High Strength Bolt ◽  
Working Face ◽  
Key Factor ◽  
Roadway Support ◽  
Working Resistance ◽  
Surrounding Rock Deformation

AbstractIn coal mining roadway support design, the working resistance of the rock bolt is the key factor affecting its maximum support load. Effective improvement of the working resistance is of great significance to roadway support. Based on the rock bolt’s tensile characteristics and the mining roadway surrounding rock deformation, a mechanical model for calculating the working resistance of the rock bolt was established and solved. Taking the mining roadway of the 17102 (3) working face at the Panji No. 3 Coal Mine of China as a research site, with a quadrilateral section roadway, the influence of pretension and anchorage length on the working resistance of high-strength and ordinary rock bolts in the middle and corner of the roadway is studied. The results show that when the bolt is in the elastic stage, increasing the pretension and anchorage length can effectively improve the working resistance. When the bolt is in the yield and strain-strengthening stages, increasing the pretension and anchorage length cannot effectively improve the working resistance. The influence of pretension and anchorage length on the ordinary and high-strength bolts is similar. The ordinary bolt’s working resistance is approximately 25 kN less than that of the high-strength bolt. When pretension and anchorage length are considered separately, the best pretensions of the high-strength bolt in the middle of the roadway side and the roadway corner are 41.55 and 104.26 kN, respectively, and the best anchorage lengths are 1.54 and 2.12 m, respectively. The best anchorage length of the ordinary bolt is the same as that of the high-strength bolt, and the best pretension for the ordinary bolt in the middle of the roadway side and at the roadway corner is 33.51 and 85.12 kN, respectively. The research results can provide a theoretical basis for supporting the design of quadrilateral mining roadways.

scholarly journals Study on the Influence of Anchorage Length and Pretension on the Working Resistance of Rock Bolt Based on its Tensile Characteristics

2021 ◽  
Author(s):  
Jucai Chang ◽  
Kai He ◽  
Dongdong Pang ◽  
Dong Li ◽  
Chuanming Li ◽  
...  
Keyword(s):  
High Strength ◽  
Rock Bolt ◽  
Support Design ◽  
Anchorage Length ◽  
High Strength Bolt ◽  
Working Face ◽  
Key Factor ◽  
Roadway Support ◽  
Working Resistance ◽  
Surrounding Rock Deformation

Abstract In coal mining roadway support design, the working resistance of the rock bolt is the key factor affecting its maximum support load. Effective improvement of the working resistance is of great significance to roadway support. Based on the rock bolt’s tensile characteristics and the mining roadway surrounding rock deformation, a mechanical model for calculating the working resistance of the rock bolt is established and solved. Taking the mining roadway of the 17102 (3) working face at the Panji 3# Well Coal Mine of China as a research site, with a quadrilateral section roadway, the influence of pretension and anchorage length on the working resistance of high-strength and ordinary rock bolts in the middle and corner of the roadway is studied. The results show that when the bolt is in the elastic stage, increasing the pretension and anchorage length can effectively improve the working resistance. When the bolt is in the yield and strain-strengthening stages, increasing the pretension and anchorage length cannot effectively improve the working resistance. The influence of pretension and anchorage length on the ordinary and high-strength bolts is similar. The ordinary bolt’s working resistance is approximately 25 kN less than that of the high-strength bolt. When pretension and anchorage length are considered separately, the best pretensions of the high-strength bolt in the middle of the roadway side and the roadway corner are 41.55 and 104.26 kN, respectively, and the best anchorage lengths are 1.54 and 2.12 m, respectively. The best anchorage length of the ordinary bolt is the same as that of the high-strength bolt, and the best pretension for the ordinary bolt in the middle of the roadway side and at the roadway corner is 33.51 and 85.12 kN, respectively. The research results can provide a theoretical basis for supporting the design of quadrilateral mining roadways.

Comparison and Application of High Prestress and Intensive Support System in Close, Soft and Cracked Roadway Support

2012 ◽  
Vol 524-527 ◽  
pp. 29-35
Author(s):  
Bin Hu ◽  
Hong Pu Kang ◽  
Jian Lin
Keyword(s):  
Support System ◽  
High Strength ◽  
Support Effect ◽  
Test Results ◽  
Support Design ◽  
Main Factors ◽  
Roadway Support ◽  
Roadway Deformation

Based on the analysis of support effect under original support design at Hongmiao Colliery, the paper summarized the main factors causing the destruction of roadways under neighboring gob areas, and pointed that the low pre-tension of the former support system and the irrationality of auxiliary support components were the main reasons for the failure of roadway support. The high prestress and intensive bolt-cable support system was recommended to reinforce roadways of this type, and the industrial on-site trial had been carried out in the transportation roadway of the Panel One of 5-2s Block, located at District 5. The test results showed that such measures as full encapsulation with high pre-tension for bolts and cables and auxiliary components with larger section and high strength could be used to effectively control roadway deformation. They provided an effective approach for the support of roadways under similar conditions.

scholarly journals Theoretical Research on the Gas Phase Density Change in Processes Occurring During Work of the Transport Module Intended for Transport From the Seabed

2018 ◽  
Vol 1 (1) ◽  
pp. 597-604
Author(s):  
Wiktor Filipek ◽  
Krzysztof Broda
Keyword(s):  
Gas Phase ◽  
High Energy ◽  
Point Of View ◽  
Theoretical Research ◽  
Reduced Form ◽  
Phase Density ◽  
Marine Deposits ◽  
Polymetallic Nodules ◽  
Degree Equation ◽  
Seafloor Massive Sulphides

Abstract In recent years, we have observed a great interest in the exploitation of marine deposits by various methods of mining and transport to the surface. However, obtaining natural resources deposited at greater depths such as polymetallic nodules and seafloor massive sulphides – SMS creates a lot of challenges for both scientists and engineers. The solutions developed so far, unfortunately, have so far been characterized by high energy consumption. For several years the authors have been conducting theoretical and experimental research on new concepts of seabed to surface transport. The results of them have been presented in previous publications. This publication presents the results of the continuation of research on the concept of construction and operation of an autonomous transport module (submitted for printing). It focuses on a theoretical analysis of the change in gas phase density in the processes occurring during operation of the transport module intended for transport from the seabed. For this purpose, a reduced form of the van der Waals equation was used in the form of a third-degree equation for parameters interested from the point of view of the transport module.

Coal Seam Roadway Bolt Support Design Method Based on the Supporting Theory of Broken Rock Zone

2013 ◽  
Vol 734-737 ◽  
pp. 535-539
Author(s):  
Hai Yuan Liu ◽  
Zhi Gang Wang ◽  
Ji Li ◽  
Lang Bai
Keyword(s):  
Theoretical Foundation ◽  
Design Method ◽  
Field Application ◽  
Surrounding Rock ◽  
Support Design ◽  
Roadway Support ◽  
The Stability ◽  
Comprehensive Classification ◽  
Classification Index ◽  
Surrounding Rock Deformation

broken rock zone is the main reason for the convergence of surrounding rock deformation, and its thickness not only is a reflection of many factors which influence the stability of surrounding rock, but also is the results of the interaction of many factors, a comprehensive classification index. Roadway support design based on classification result of broken rock zone, has a solid theoretical foundation, and the field application effect is remarkable.

scholarly journals Improved energy balance theory applied to roadway support design in deep mining

2018 ◽  
Vol 15 (4) ◽  
pp. 1588-1601 ◽  
Author(s):  
Chunlai Wang ◽  
Lu Liu ◽  
Davide Elmo ◽  
Feng Shi ◽  
Ansen Gao ◽  
...  
Keyword(s):  
Energy Balance ◽  
Balance Theory ◽  
Support Design ◽  
Deep Mining ◽  
Roadway Support

scholarly journals An Innovative Elastoplastic Analysis for Soft Surrounding Rock considering Supporting Opportunity Based on Drucker-Prager Strength Criterion

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Rui Wang ◽  
Xu-dong Liu ◽  
Jian-biao Bai ◽  
Shuai Yan ◽  
Jun Xu
Keyword(s):  
Strength Criterion ◽  
Homogenization Method ◽  
Surrounding Rock ◽  
Theoretical Research ◽  
Underground Engineering ◽  
Support Design ◽  
Interval Distance ◽  
Space Effect ◽  
The Stability ◽  
Supporting Condition

In order to study the mechanism of excavation and supporting process of equivalent circular roadway, the model of soft roadway was established firstly. The elastoplastic solutions in excavation process were deduced based on Drucker-Prager strength criterion. Then, the elastoplastic solution under supporting condition was obtained based on homogenization method under the condition of rockbolts and liner supporting. Lastly, an example was analyzed to study the effect of different factors such as “space effect,” supporting opportunity, stresses, surrounding displacement, and the radius of plastic zone. Based on theoretical research case, the change rules of considering the “space effect” and the supporting opportunity when calculating the subarea of the roadway were discussed, the control of interval distance of rockbolts on the displacement of surrounding rock mainly reflecting in the plastic residual zone and the “space effect” in excavation, and the supporting time to control the displacement of surrounding rock not being ignored are revealed. The results can provide an important theoretical basis for the stability evaluation and quantitative support design of roadway surrounding rock. Therefore, the “space effect” and the supporting time to control the displacement and stresses of surrounding rock can not being ignored in underground engineering.

scholarly journals Study of the Stability Control of Rock Surrounding Longwall Recovery Roadways in Shallow Seams

2020 ◽  
Vol 2020 ◽  
pp. 1-22
Author(s):  
Cheng Zhu ◽  
Yong Yuan ◽  
Zhongshun Chen ◽  
Chaogui Meng ◽  
Shengzhi Wang
Keyword(s):  
Rock Pressure ◽  
Coal Mine ◽  
Stability Control ◽  
Control Effect ◽  
Support Design ◽  
Key Strata ◽  
Key Stratum ◽  
Discriminative Approach ◽  
The Stability ◽  
Working Resistance

The rock pressure appearance of longwall faces in shallow seams is generally violent, and roofs and supports are susceptible to damage during equipment extraction. Stability control of the rock surrounding longwall recovery roadways allows safe and rapid equipment extraction. Herein, via theoretical analysis, numerical simulations, and field observations, the stability control of the rock surrounding recovery roadways is studied to ensure the release of the accumulated rock pressure on the roof, the working resistance of the supports and the reasonableness of the recovery roadway support design. Pressure-relief technology is introduced to release the accumulated rock pressure before equipment extraction, and a discriminative approach is proposed to determine the breaking and articulated forms of key strata and broken blocks, respectively. On this basis, mechanical models of roof instability are established based on four key stratum structures in the overburden of shallow seams. Methods for calculating a reasonable working resistance for supports are discussed. Finally, Liangshuijing Coal Mine and Fengjiata Coal Mine are taken as research objects to evaluate the roof stability of recovery roadways based on observations of weighting characteristics. The support working resistances and reasonable recovery roadway widths under three key stratum structures are determined. Considering the time effect of plastic zone development, the support design of recovery roadways is optimized. FLAC2D software simulates the surrounding rock control effect of two support designs, and roof subsidence curves are obtained. The results show that the key to equipment extraction in shallow seams is to ensure that supports have reasonable working resistances and to improve the support of recovery roadways. The results provide a reference for the selection and extraction of supports in shallow seam faces.

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