scholarly journals Control Technology of Soft Rock Floor in Mining Roadway with Coal Pillar Protection: A case study

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 3009 ◽  
Author(s):  
Housheng Jia ◽  
Luyao Wang ◽  
Kai Fan ◽  
Bo Peng ◽  
Kun Pan
Keyword(s):  
Coal Pillar ◽  
Field Tests ◽  
Soft Rock ◽  
High Strength ◽  
Main Roof ◽  
Deformation And Failure ◽  
Maximum Deformation ◽  
Plastic Failure ◽  
Floor Heave ◽  
Stress Environment

This study considered the mining roadway with coal pillar protection in the fully mechanized caving face of the Dananhu No.1 Coal Mine, China. Theoretical analysis, numerical simulation, and field tests were conducted, and the stress environment, deformation, and failure characteristics of the mining roadway in the fully mechanized caving face were analyzed. The results revealed that the intrinsic cause for the large asymmetrical floor deformation in the mining roadway is the asymmetrical phenomenon of the surrounding rock’s stress environment, caused by mining. This also results in the non-uniform distribution of the mining roadway floor’s plastic zone. The degree of asymmetrical floor heave is internally related to the thickness of the caving coal. When the thickness of the caving coal was in the range of 5.9 m, the deformation of the asymmetrical floor heave, caused by the plastic failure in the floor, became more obvious as certain parameters increased. As the rotation angle of the principal stress direction increased, the maximum plastic failure depth position of the floor gradually moved toward the middle of the roadway. This caused a different distribution for the maximum deformation position. The control of the floor heave deformation was poor, and it was not feasible to use high-strength support under the existing engineering conditions. Hence, the control should mainly be applied to the floor heave deformation. When the thickness of the caving coal was more than 5.9 m, the main roof strata was prone to instability and being cut along the edge of the coal pillar; the rock stress environment surrounding the roadway tended to revert back to the initial geostress state. The proposed floor heave control strategy achieved good results, and as the deformation of the floor heave decreased, the workload of the floor heave was also greatly reduced.

New Type of High-Strength Support in Deep Soft Rock Roadway

2013 ◽  
Vol 724-725 ◽  
pp. 1520-1525
Author(s):  
Ji Cheng Feng ◽  
Hong Jiao Li ◽  
Zhi Chao Zhao ◽  
Wen Long Zhang
Keyword(s):  
Comparative Analysis ◽  
Bending Strength ◽  
Soft Rock ◽  
High Strength ◽  
Field Application ◽  
Good Effect ◽  
Deformation And Failure ◽  
Pumping Station ◽  
Arch Support ◽  
Working Resistance

In order to control the deformation of large section surrounding rock in 700m level of the main drainage pumping station in the experimental mine, according to the reason for deformation and failure of the main drainage pumping station and material mechanics, fully-closed U-shaped support which used double welding I-steel bottom arch as the main structure was designed and the assembly and principles of support were described in detail, based on theoretical calculation and comparative analysis on the structure and mechanical properties of rectangular I-beam support, U-steel support, single I-beam arch support and double I-beam arch support. Based on the comparative analysis by numerical simulation, the rationality of the high strength support and the detailed support parameters were determined. It gets good effect in field application and ensures the long-term stability of the main drainage pumping station. The results show that: the double-layer I-beam 12# can increase bending strength by about 7.5 times. Double trough splint device used in shoulder of the support has the advantages of high strength, greater rigidity, good pliability and stable working resistance.

Simulation Analysis of the Soft Rock Inclined Shaft Surrounding Rock Control with Different Bolt Support Patterns

2014 ◽  
Vol 988 ◽  
pp. 377-382 ◽  
Author(s):  
Peng Fei Jiang
Keyword(s):  
Compressive Stress ◽  
Simulation Analysis ◽  
Soft Rock ◽  
High Strength ◽  
Surrounding Rock ◽  
Tension Stress ◽  
Deformation And Failure ◽  
Stress And Deformation ◽  
Rock Strata ◽  
Bolt Support

Taking +150 inclined shaft going through the soft rock strata at Muchengjian mine as the background, and based on the analysis of the deformation and failure feature of the roadway surrounding rock in the soft rock strata, this paper makes X-Ray Differaction (XRD) phase analysis of the soft rock; using finite difference numerical software FLAC3D, it stimulates and makes comparative analysis of the stress and deformation distribution characteristics of the roadway surrounding rock with bolt support with different intervals, and the support of the high-strength bolt with high pre-tension stress in the inclined shaft through the soft rock strata. The results show that the roadway surrounding rock in the +150 inclined shaft at Muchengjian mine is swelling soft rock prone to softening, degradation and swelling in water, which is bad for the roadway support; different types of rock strata have significant different impact on the stress and deformation of the roadway surrounding rock; for the soft rock roadway, the increased pre-tension stress of the bolt can cause higher compressive stress in the roadway surrounding rock and reduce the tension failure of the surrounding rock;compared with the end anchorage, the full-size anchorage with high pre-tension stress can cause the overlap of the conical compressive stress zone and enhance the roadway overall support.

Supporting Technics of Easily Mudding and Ultrahigh Roadway in Soft Coal Rock

2014 ◽  
Vol 988 ◽  
pp. 211-217 ◽  
Author(s):  
Zhen Zhang
Keyword(s):  
Simulation Method ◽  
Field Application ◽  
Structure Stability ◽  
Deformation And Failure ◽  
Soft Coal ◽  
Floor Heave ◽  
Coal Rock ◽  
Stress Environment ◽  
Roadway Deformation ◽  
Two Sides

According to the situation of the great height wall, soft and weak surrounding rocks and sliming characteristics of the 15# coal west-third panel sump in the Gushuyuan mine, the deformation characteristics and mechanism of the sump were analyzed by field survey, laboratory tests and the numerical simulation method. The results show that the sump deformation and failure were determined by its low strength, weakness structural, sliming characteristics and excavation disturbance. The roadway deformation occurs mainly in the middle, upper and lower of the sides and the floor. A comprehensive solution is proposed, including sealing surrounding rocks, strengthening soft and weak surrounding rocks, strengthening the structure stability, improving the surrounding rocks stress environment. This method was applied in the coal mine. Field application results show that this method was suitable for control sump deformation, the maximum roadway roof subsidence is 15 mm, the two sides convergence is 30mm, and the maximum amount of floor heave is 21mm.

scholarly journals Research on Key Technologies of Floor Heave Control in Soft Rock Roadway

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Lei Shi ◽  
Haidong Zhang ◽  
Peng Wang
Keyword(s):  
Simulation Analysis ◽  
Treatment Plan ◽  
Soft Rock ◽  
High Strength ◽  
Mine Safety ◽  
Engineering Practice ◽  
Efficient Production ◽  
Metal Mesh ◽  
Deformation Control ◽  
Floor Heave

Aiming at the floor heave of transportation concentrated roadway on the West Wing (TCRWW) of No. 1 Coal Seam in Danhou Mine, it affects underground coal transportation and mine safety production. First, the lithology and structure of the roadway floor were sampled and tested, and it was found that it contained clay minerals with high hydrophilicity. Secondly, starting from the mechanical mechanism of the roadway floor, a mechanical model of the roadway floor is established. By increasing the floor anchoring layer thickness m1, the floor deformation can be effectively controlled to guarantee the stability of the surrounding rock of the roadway. Thirdly, the FLAC3D numerical simulation analysis of the roadway deformation under the existing support scheme of the roadway is consistent with the measured deformation results on-site, thereby revealing that the existing support scheme and parameters are not reasonable. Finally, the unreasonable support scheme and parameters of the existing roadway were disclosed, and an antifloor arch structure was proposed: “quicklime bottom paving + prestressed anchor cable + concrete arc beam + metal mesh + C20 high-strength concrete filling.” This floor treatment plan is adopted for the industrial verification of the test section of TCRWW. Engineering practice shows that the optimized roadway support scheme has a better effect on the deformation control of the roof-to-floor and rib-to-rib, thereby effectively ensuring safe and efficient production in the mine.

scholarly journals Field and Numerical Investigation on the Coal Pillar Instability of Gob-Side Entry in Gently Inclined Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xupeng Ta ◽  
Zhijun Wan ◽  
Yuan Zhang ◽  
Peng Shi ◽  
Zejie Wei ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Pillar ◽  
Main Roof ◽  
Horizontal Stress ◽  
Practical Significance ◽  
Pillar Stability ◽  
Deformation And Failure ◽  
Asymmetric Deformation ◽  
Collaborative Control ◽  
Seam Mining

In order to study the coal pillar stability of gob-side entry in gently inclined coal seam, a comprehensive method including theoretical analysis, numerical modeling, and field monitoring was applied to study its fracturing and instability mechanism. The results show that the uneven horizontal stress was the internal cause of entry asymmetric deformation and failure in inclined coal seam. In gently inclined coal seam, the rotation movement of the main roof and stress distribution were closely related to inclination of the coal seam. Based on the asymmetric deformation characteristics and mechanisms of entry, a collaborative control technology of roof cutting for pressure relief and support strengthening has been put forward. The research results have practical significance for revealing the mechanism of entry damage in gently inclined coal seam mining and proposing engineering measures to prevent coal pillar damage and disaster occurrence.

scholarly journals Study on the Large Deformation Characteristics and Disaster Mechanism of a Thin-Layer Soft-Rock Tunnel

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Xiulian Zhang ◽  
Manchao He ◽  
Fengnian Wang ◽  
Gan Li ◽  
Shengxin Xu ◽  
...  
Keyword(s):  
Thin Layer ◽  
Water Absorption ◽  
Large Deformation ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Left Shoulder ◽  
Deformation And Failure ◽  
Maximum Deformation ◽  
Factors Influencing ◽  
Main Factors

In view of the large deformation of thin-layer soft rock in the No. 2 inclined shaft of the Muzhailing Tunnel, we performed an experimental investigation on the mineral composition, physical characteristics, and uniaxial compressive strength of the surrounding rock of the tunnel. The characteristics of the large deformation of the surrounding rock of the tunnel were analyzed, and the main factors influencing the deformation of the tunnel were revealed. The influence of various factors on the large deformation of the surrounding rock was analyzed using the 3DEC-Trigon discrete element numerical simulation method. The results show that (1) the deformation of the surrounding rock of the tunnel has remarkable asymmetry, the deformation of the initial support of the tunnel is significant, and the buried depth of the area where the maximum deformation of the tunnel exceeded 1 m is greater than 500 m; (2) the main factors influencing the deformation of a thin-layer slate tunnel include joint inclination, buried depth, water absorption, and softening of the surrounding rock; and (3) the maximum deformation of the surrounding rock is observed for a joint angle of 45°, at which the buried depth is directly proportional to the deformation and failure of the tunnel. Furthermore, after the surrounding rock was softened by water absorption, the floor of the tunnel, the left shoulder socket, and the right side of the tunnel are deformed greatly. The results of this study will provide a theoretical basis for the study of similar deformation control methods and supporting measures for tunnels excavated in thin-layer soft rock.

An experimental technique for studying the behavior of high-strength steel under static punching

2021 ◽  
Vol 103 (3) ◽  
pp. 117-122
Author(s):  
Valeriy Kharchenko ◽  
Оleg Каtоk ◽  
Roman Kravchuk ◽  
Andriy Kravchuk ◽  
Alyona Sereda
Keyword(s):  
High Strength Steel ◽  
High Strength Steels ◽  
Field Tests ◽  
High Strength ◽  
Testing Procedure ◽  
Full Scale ◽  
Deformation And Failure ◽  
Static And Dynamic Loads ◽  
Materials Behavior ◽  
Expensive Process

High-strength steels are widely used in the defense and civil industries. During operation, high-strength and armored steels are subjected to extreme static and dynamic loads. Material specimens or full-scale structures testing at such loads is a very complex and expensive process. Therefore, numerical calculation methods are commonly used to assess their strength. To determine the parameters of these models as an express method, it is reasonable to use tests that are similar in nature of the loading, deformation, and failure to full-scale or standard ones, but which are cheaper and easier to perform in the laboratory conditions. One of the key properties of high-strength steels is their resistance to penetration by various types of armor-piercing strikers. To simplify the testing procedure and minimize materials consumption, static and dynamic punching methods have been developed. A set of experimental and numerical investigations on the deformation of various specimens from high-strength steels has been made under static and dynamic load conditions, in particular, plate specimens punching (punches of different shapes) by the G. S. Pisarenko Institute for Problems of Strength of the NAS of Ukraine. This paper presents the experimental procedure and equipment for the investigation of the materials’ behavior under static punching. High-strength steel plate specimens have been tested on an upgraded servohydraulic machine Instron 8802 using three types of punches: flat, spherical, and conical. It is established that the diagram describing the spherical punching is the most informative, while the diagram showing the conical punching is less informative. The nature of the specimen fracture is consistent with the results of field tests in the barrier penetration by armor-piercing strikers. The obtained results are in good agreement with the known literature data and can be used to validate the results obtained by numerical simulations.

scholarly journals Research on Supporting Method for High Stressed Soft Rock Roadway in Gentle Dipping Strata of Red Shale

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 423
Author(s):  
Chunde Ma ◽  
Jiaqing Xu ◽  
Guanshuang Tan ◽  
Weibin Xie ◽  
Zhihai Lv
Keyword(s):  
Failure Process ◽  
High Stress ◽  
Soft Rock ◽  
In Situ Stress ◽  
Mechanical Parameters ◽  
Deformation And Failure ◽  
Deep Mine ◽  
Plastic Energy ◽  
Roadway Stability ◽  
Phosphate Mine

Red shale is widely distributed among the deep mine areas of Kaiyang Phosphate Mine, which is the biggest underground phosphate mine of China. Because of the effect of various factors, such as high stress, ground water and so on, trackless transport roadways in deep mine areas were difficult to effectively support for a long time by using traditional supporting design methods. To deal with this problem, some innovative works were carried out in this paper. First, mineral composition and microstructure, anisotropic, hydraulic mechanical properties and other mechanical parameters of red shale were tested in a laboratory to reveal its deformation and failure characteristics from the aspect of lithology. Then, some numerical simulation about the failure process of the roadways in layered red shale strata was implemented to investigate the change regulation of stress and strain in the surrounding rock, according to the real rock mechanical parameters and in-situ stress data. Therefore, based on the composite failure law and existing support problems of red shale roadways, some effective methods and techniques were adopted, especially a kind of new wave-type bolt that was used to relieve rock expansion and plastic energy to prevent concentration of stress and excess deformation. The field experiment shows the superiorities in new techniques have been verified and successfully applied to safeguard roadway stability.

Stability Prediction of Surrounding Rocks and Optimum Design of Roof-Bolt Parameters in Deep Roadway

2013 ◽  
Vol 353-356 ◽  
pp. 436-439
Author(s):  
De Sen Kong ◽  
Yong Po Chen
Keyword(s):  
Prediction Method ◽  
Simulation Method ◽  
Complex Stress ◽  
Roof Bolt ◽  
Deformation And Failure ◽  
Long Run ◽  
Research Findings ◽  
Stress Environment ◽  
Classification Prediction ◽  
The Stability

In order to forecast the stability of deep roadway and optimize the parameters of bolts, the complex stress environment and the multivariate surrounding rocks characteristics of deep roadway were analyzed. Then the classification prediction method and the numerical simulation method were simultaneously used to analysis the stability of surrounding rocks. Furthermore, the supporting parameters of bolts were also designed optimally. It was shown that the characteristics of stress distribution, deformation and failure zone of surrounding rocks are not ideal. So it is necessary to optimize the supporting parameters of deep roadway. All these research findings will provide the theory basis for bolts of deep roadway and will ensure the optimization of bolts and the stability of deep roadway in the long run.

High Strength Combined Support Technology in Deep High Stress Soft Rock Roadway

2012 ◽  
Vol 524-527 ◽  
pp. 598-603
Author(s):  
Nian Jie Ma ◽  
Zhi Qiang Zhao ◽  
Hua Zhao ◽  
Li Shuai Jiang
Keyword(s):  
High Stress ◽  
Soft Rock ◽  
High Strength ◽  
Parameter Determination ◽  
Test Results ◽  
Actual Measurement ◽  
Computer Numerical Simulation ◽  
Soft Rock Roadway ◽  
Rock Roadway

In order to solve the serious damage and repeat revision problem of high stress soft rock roadway in deep -950 level of Tangshan coal mine, based on the theory of the maximum stress level, together with the actual measurement of geostress and the laboratory mechanical parameters of rock-core and computer numerical simulation, the high strength combined support technology and supporting parameters are determined and the engineering test has been done. The engineering test results show that the parameter determination of high strength combined support technology, which based on the actual measurement of geostress, can effective solve the support issue of high stress soft rock roadway and provide useful experience for similar engineering problems.

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