scholarly journals Experimental Test on Nonuniform Deformation in the Tilted Strata of a Deep Coal Mine

2021 ◽  
Vol 13 (23) ◽  
pp. 13280
Author(s):  
Hai Wu ◽  
Qian Jia ◽  
Weijun Wang ◽  
Nong Zhong ◽  
Yiming Zhao
Keyword(s):  
High Stress ◽  
Stability Control ◽  
Surrounding Rock ◽  
Experimental Results ◽  
Lower Side ◽  
Reinforcement Scheme ◽  
Deformation And Failure ◽  
True Triaxial ◽  
Deep Mine ◽  
Deep Coal Mine

Taking a deep-mine horizontal roadway in inclined strata as our research object, the true triaxial simulation technique was used to establish a model of the inclined strata and carry out high-stress triaxial loading experiments. The experimental results show that the deformation of surrounding rock in the roadway presents heterogeneous deformation characteristics in time and space: the deformation of the surrounding rock at different positions of the roadway occurs at different times. In the process of deformation of the surrounding rock, deformation and failure occur at the floor of the roadway first, followed by the lower shoulder-angle of the roadway, and finally the rest of the roadway. The deformation amount in the various areas is different. The floor heave deformation of the roadway floor is the greatest and shows obvious left-right asymmetry. The deformation of the higher side is greater than that of the lower side. The model disassembly shows that the development of cracks in the surrounding rock is characterized by more cracks on the higher side and fewer cracks on the lower side but shows larger cracks across the width. The experimental results of high-stress deformation of the surrounding rock are helpful in the design of supports, the reinforcement scheme, and the parameter optimization of roadways in high-stress-inclined rock, and to improve the stability control of deep high-stress roadways.

Investigation on Deformation and Failure Characteristics and Stability Control of Soft Rock Roadway Surrounding Rock in Deep Coal Mine

2011 ◽  
Vol 255-260 ◽  
pp. 3711-3716 ◽  
Author(s):  
Ju Cai Chang ◽  
Guang Xiang Xie
Keyword(s):  
Coal Mine ◽  
Plastic Region ◽  
Soft Rock ◽  
Stability Control ◽  
Surrounding Rock ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Deep Coal Mine ◽  
Soft Rock Roadway ◽  
Rock Roadway

Numerical simulation and field measurement were carried out to investigate into laws of deformation and movement and the evolving characteristics of the plastic region around the roadway based on engineering conditions of deep soft rock roadway in Wangfenggang colliery, Huainan Mining area. The mechanism of controlling the surrounding rock stability of soft rock roadway in deep coal mine was demonstrated. The supporting of soft rock roadway in deep coal mine must be compatible with deformation and failure characteristics of surrounding rock, and it can keep the stability of surrounding rock. The combined supporting with high strength and prestress bolting-anchoring and integral surrounding rock grouting reinforcement can effectively control the surrounding rock deformation of soft rock roadway in deep coal mine. But every working step must be pay attention to sequence on the time and space so that it can play an integral supporting effect. Research results are put into practice accordingly and good control effect has been achieved.

Deformation Failure Analysis and Stability Control Technology of Large Section Soft Rock Chamber in Deep Coal Mine

2013 ◽  
Vol 353-356 ◽  
pp. 1035-1039
Author(s):  
Chang Hui An ◽  
Gui Bin Zhang ◽  
Zhi Da Liu ◽  
Kai Zhao ◽  
Wei Guo ◽  
...  
Keyword(s):  
Coal Mine ◽  
Soft Rock ◽  
Stability Control ◽  
Surrounding Rock ◽  
Mine Safety ◽  
Large Section ◽  
Deformation And Failure ◽  
Deep Coal Mine ◽  
Ground Pressure ◽  
The Impact

The chambers of certain coal mine in Shandong such as central substation situate in soft rock which consists of mudstone and fine sandstone, etc. Obvious ground pressure behaviors, large deformation and failure of surrounding rock have serious effect on mine safety production, with the impact of various complicated deep large ground pressure. This paper presents a rational scheme to control the surrounding rock steadily, based on analysis of deformation and failure on large section soft rock chamber, combined with the concept of the" combined supporting technology of long and short anchors" and "the combined supporting technology of three anchors".

scholarly journals Deformation Mechanism and Surrounding Rock Control in High-Stress Soft Rock Roadway: A Case Study

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yuwen Gao ◽  
Chen Wang ◽  
Yong Liu ◽  
Yuyang Wang ◽  
Lianchang Han
Keyword(s):  
Theoretical Analysis ◽  
High Stress ◽  
Soft Rock ◽  
Stability Control ◽  
Steel Tube ◽  
Field Application ◽  
Industrial Test ◽  
Surrounding Rock ◽  
Guizhou Province ◽  
Deformation And Failure

Stability control for soft and broken surrounding rock of roadways is one important segment of mining support. Taking 1412 Roadway of a mine in Guizhou province as a research background, this paper studies the large deformation of surrounding rock and the failure of bolts and cables. The deformation and failure mechanism are analyzed by related theoretical analysis and field survey. Then, the feasibility of the composite controlling scheme, bolts and cables + grouting + steel tube concrete support, is verified by theoretical analysis, numerical simulation, and industrial test. Following results can be obtained: main reasons leading to the deformation of surrounding rock and the failure of cables and blots in the roadway are low strength and poor self-stability of surrounding rock, complex stress environment, low support resistance, and lack of reinforced support in crucial supporting sites; the control scheme can reduce the surrounding rock deformation by 40%, which meets the requirements of field application so that this practice can provide some guidance for other similar projects.

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.

scholarly journals Research on Control Mechanism of Surrounding Rock of Deep Gob-Side Entry Retaining

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jianxiong Liu ◽  
Jingke Wu ◽  
Yun Dong ◽  
Yanyan Gao ◽  
Jihua Zhang ◽  
...  
Keyword(s):  
Large Deformation ◽  
High Stress ◽  
Original System ◽  
Field Investigation ◽  
Surrounding Rock ◽  
Eccentric Load ◽  
Deformation And Failure ◽  
Body Fracture ◽  
Stress States ◽  
Term Creep

To address the large deformation of the surrounding rock of deep gob-side entry retaining under high stress, lithological characteristics of the surrounding rock and failure model of support body and their evolutionary processes are analyzed through field investigation and theoretical analysis. Failure mechanisms of surrounding rock and the technology to control it are studied systematically. The results show that the causes of the large deformation of the surrounding rock are weak thick mudstones with softening property and water absorption behavior, as well as its fragmentation, dilatancy, and long-term creep during strong disturbance and highly centralized stress states. The cross-section shape of the roadway after deformation and failure of the surrounding rock is obviously asymmetric in both the horizontal and vertical directions. Since the original system supporting the surrounding rock is unable to completely bear the load, each part of the supporting system is destroyed one after the other. The failure sequences of the surrounding rock are as follows: (1) roadway roof fracture in the filling area, (2) filling body fracture under eccentric load, (3) rapid subsidence of the roadway roof, and (4) external crack drum and rib spalling at the solid coal side. Due to this failure sequence, the entire surrounding rock becomes unstable. A partitioned coupling support and a quaternity control technology to support the surrounding rock are proposed, in which the roof of the filling area plays a key role. The technology can improve the overall stability of gob-side entry retaining, prevent support structure instability caused by local failure of the surrounding rock, and ensure the safety and smoothness of roadways.

scholarly journals Surrounding Rock Stability Control Technology of Roadway in Large Inclination Seam with Weak Structural Plane in Roof

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 881
Author(s):  
Peng Wu ◽  
Liang Chen ◽  
Ming Li ◽  
Lan Wang ◽  
Xufeng Wang ◽  
...  
Keyword(s):  
Stability Control ◽  
Surrounding Rock ◽  
Wire Mesh ◽  
Rock Surface ◽  
Control Technology ◽  
Structural Plane ◽  
Deformation And Failure ◽  
Total Displacement ◽  
Rock Stability ◽  
Wire Meshes

The surrounding rock control technology of mining roadways in large inclination seams with a weak structural plane in the roof is one of the most challenging fields in underground roadway support. In view of the serious deformation of the surrounding rock of the transportation roadway in the 1201 working face of a mine, the deformation and failure characteristics and instability mechanism of the surrounding rock of the roadway are analysed. The self-stability mechanical model of the roof block structure of the roadway with a large inclination under the support effect is established, and the support concept of “high pre-stressed asymmetric” and the combined support method of bolts, wire mesh, and cables are proposed. The rationality of the supporting scheme is verified by numerical simulation. The results show that: compared with bolt and wire mesh support, the maximum shear displacement of the roof’s weak layer under the combined support of bolt, wire meshes, and cable before and after mining is reduced by 86.78% and 83%, respectively, and the maximum total displacement of surrounding rock surface is reduced by 49.22% and 37.1%, respectively. The field monitoring results show that the combined support scheme can effectively control the deformation of the surrounding rock.

scholarly journals Research on the Reasonable Strengthening Time and Stability of Excavation Unloading Surrounding Rock of High-Stress Rock Mass

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Wensong Xu ◽  
Wentao Xu ◽  
Yunhai Cheng
Keyword(s):  
Rock Mass ◽  
Plastic Zone ◽  
Failure Process ◽  
High Stress ◽  
Stable State ◽  
Surrounding Rock ◽  
Triaxial Tests ◽  
Uniaxial Compression Test ◽  
True Triaxial ◽  
True Triaxial Tests

This study is aimed at better understanding the deformation and failure mechanism of surrounding rock during excavation unloading of a high-stress rock mass and determining the reasonable reinforcement time for the surrounding rock. To fulfill this aim, true triaxial tests were carried out on different loading and unloading paths during the unilateral unloading of a high-stress rock mass. The variational condition for minimization of plastic complementary energy is obtained, the optimal reinforcement time is determined, and the range of the plastic zone in the surrounding rock reinforced by anchor mesh-cable-grouting is compared and analyzed. The results are as follows: (1) Based on the Mohr-Coulomb yield criterion and the deformation reinforcement theory of surrounding rock, the stable state with the minimum reinforcement force is obtained. (2) After the true triaxial tests on the unilateral unloading of the third principal stress were carried out under different confining pressures, loading continued to be performed. Compared with rock failure without confining pressure, in the conventional uniaxial compression test, the failure of samples is dominated by composite splitting-shear failure; the unilateral unloading stress-concentration failure is a progressive failure process of splitting into plates followed by cutting into blocks and then the ejection of blocks and pieces. (3) The relationship between the time steps of the surrounding rock stability and the excavation distance is obtained. The supporting time can be divided into four stages: presupport stage, bolt reinforcement stage, anchor cable reinforcement stage, and grouting reinforcement stage. (4) In the range of within 5 m behind the tunneling face, the plastic zone of the surrounding rock with support is reduced by 7 m as compared with that with no support. In the range of over 5 m behind the tunneling face, the plastic zone of the roadway floor with support is reduced by 2.6 m as compared with that without support, and the deformation is reduced by 90%. These results can serve as a reference for controlling the behavior of surrounding rock during excavation unloading of high-stress rock masses.

scholarly journals Investigation on Surrounding Rock Stability Control Technology of High Stress Roadway in Steeply Dipping Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Honglin Liu ◽  
Chen Xu ◽  
Hongzhi Wang ◽  
Guodong Li ◽  
Sanyang Fan
Keyword(s):  
Distinct Element ◽  
High Stress ◽  
Horizontal Stress ◽  
Stability Control ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Practical Applications ◽  
Rock Stability ◽  
Distinct Element Code ◽  
Dip Angle

There are a large amount of steeply dipping coal seams deposited in China, the safe and effective extraction of which are the challenge for coal operators due to the complicated geological characteristics, in particular, when the underground roadway is excavated in the steeply dipping coal seams with limited seam distance. The Universal Distinct Element Code (UDEC) was adopted in the present research to explore the stress distribution of surrounding rock of the roadway. Based on the numerical simulation, the damage coefficient was proposed and then used to classify the roof conditions into four groups. After that, the asymmetric support technique was proposed and put into practical applications. It is indicated that the stress concentration on the floor is the main feature of the extraction of steeply dipping coal seams. Moreover, the distributions of the maximum vertical stress and horizontal stress which are much different from each other mainly attributed to the effect of the large dip angle. This research also verified the feasibility of using the asymmetric and partition support technique to maintain the integrity of the surrounding rock, as from the case study conducted at the 12032 longwall coal face of Zhongwei coal mine.

scholarly journals Deformation and Failure Characteristics and Control Technology of Roadway Surrounding Rock in Deep Coal Mines

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Jucai Chang ◽  
Dong Li ◽  
Tengfei Xie ◽  
Wenbao Shi ◽  
Kai He
Keyword(s):  
High Stress ◽  
Development Stage ◽  
Surrounding Rock ◽  
Deformation And Failure ◽  
Deformation Stage ◽  
Mining Depth ◽  
Floor Heave ◽  
Rock Tunnel ◽  
Two Sides

With the increase in mining depth, the problem of the floor heave of a roadway is becoming increasingly prominent. Solving this problem for a deep high-stress roadway is the key to ensure safe supply and utilization of coal resources in China. This study investigates the floor heave of a horizontal transportation rock roadway at the depth of 960 m at the Xieyi Mine. A four-way loading simulation test frame similar to the Xieyi Mine was used to reproduce the high-stress environment of a deep roadway by loading different pressures on the roof, floor, and two sides of the roadway. The experimental results show that after the tunnel had been excavated, the surrounding rock failure could be divided into three stages: the initial deformation stage, fissure development stage, and mild deformation stage. The destruction time periods of these stages were 0–0.5 h, 0.5–2 h, and 2–6 h, and the destruction ranges were 0.4 m, 1 m, and 1.5 m, respectively. The amount of roof subsidence, the displacement of the two sides, and the floor heave influence each other, and the range of the bearing ring (5.6 m) of the floor is larger than that of the roof (3.4 m) after the surrounding rock has been damaged. The findings suggest that the floor should be supported first, before the two sides and the roof; then, the support of the key parts (roof and floor corners) should be strengthened. The roof, floor, and two sides are considered for controlling the deformation of the surrounding rock in a coupled trinity support mode. Because of the unfavorable conditions in the area, overexcavation backfill technology was used. The new support was successfully applied during the subsequent construction of the rock tunnel. Based on the long-term monitoring results of the surrounding rock deformation, the floor heave control yielded satisfactory results and maintained the long-term stability of the roadway. Therefore, this study can serve as a reference for preventing floor heave in similar high-stress roadways in the future.

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