scholarly journals Research on Mechanism and Control of Floor Heave of Mining-Influenced Roadway in Top Coal Caving Working Face

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 381 ◽  
Author(s):  
Xingping Lai ◽  
Huicong Xu ◽  
Pengfei Shan ◽  
Yanlei Kang ◽  
Zeyang Wang ◽  
...  
Keyword(s):  
Coal Mine ◽  
High Efficiency ◽  
Soft Rock ◽  
Surrounding Rock ◽  
High Yield ◽  
Geological Investigation ◽  
Geological Conditions ◽  
Floor Heave ◽  
Damage Depth ◽  
Squeeze Effect

The stability of the surrounding rock is the key problem regarding the normal use of coal mine roadways, and the floor heave of roadways is one of the key factors that can restrict high-yield and high-efficiency mining. Based on the 1305 auxiliary transportation roadway geological conditions in the Dananhu No. 1 Coal Mine, Xinjiang, the mechanism of roadway floor heave was studied by field geological investigation, theoretical analysis, and numerical simulation. We think that the surrounding rock of the roadway presents asymmetrical shrinkage under the original support condition, and it is the extrusion flow type floor heave. The bottom without support and influence of mining are the important causes of floor heave. Therefore, the optimal support scheme is proposed and verified. The results show that the maximum damage depth of the roadway floor is 3.2 m, and the damage depth of the floor of roadway ribs is 3.05 m. The floor heave was decreased from 735 mm to 268 mm, and the force of the rib bolts was reduced from 309 kN to 90 kN after using the optimization supporting scheme. This scheme effectively alleviated the “squeeze” effect of the two ribs on the soft rock floor, and the surrounding rock system achieves long-term stability after optimized support. This provides scientific guidance for field safe mining.

scholarly journals A Case Study of Optimization and Application of Soft-Rock Roadway Support in Xiaokang Coal Mine, China

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Shuai Guo ◽  
Xun-Guo Zhu ◽  
Xun Liu ◽  
Hong-Fei Duan
Keyword(s):  
Soft Rock ◽  
Surrounding Rock ◽  
Geological Conditions ◽  
Floor Heave ◽  
Roadway Support ◽  
Soft Rock Roadway ◽  
Surrounding Rock Stress ◽  
Rock Roadway

The roadway of S2S2 fully mechanized caving face (FMCF) in Xiaokang Coal Mine is one of the most typical deep-buried soft-rock roadways in China and had been repaired several times. In order to figure out the failure reasons of the original roadway support, the geological conditions were investigated, the surrounding rock stress was monitored, the rib displacement, roof separation, and floor heave were in situ measured, and the performance of the U-shaped steel support was simulated. The above analysis results indicated that the support failure was mainly caused by (1) the unreasonable arch roadway section, (2) the high and complex surrounding rock stress, (3) the failure control of the floor heave, and (4) the inadequate self-supporting capacity of the surrounding rock. For optimizing, the roadway section was changed to circle and a new full-section combined support system of “belt-cable-mesh-shotcrete and U-shaped steel-filling behind the support” was adopted, which could specifically control the floor heave, allow the roadway deformation in control, and improve the self-supporting ability and stress field of the surrounding rock. To determine the support parameters, the selected U-shaped steel support was verified by simulation, and various bolt-cable support schemes were simulated and compared. Finally, such an optimized support scheme was applied in the roadway of the next replacement FMCF. The in situ monitoring showed that the rib-to-rib convergence and roof-to-floor convergence were both controlled within 600 mm, which indicated that the roadway was effectively controlled. This case study has important reference value and guiding function for the optimal design of the soft-rock roadway support with similar geological conditions.

Application of Grouting Reinforcement Technology in Pingshan Shaft Station

2014 ◽  
Vol 580-583 ◽  
pp. 1347-1351
Author(s):  
Liang Tian ◽  
Jing Yi Xi ◽  
Jian Liu ◽  
Xiao Dong Liu ◽  
Feng Shang ◽  
...  
Keyword(s):  
Roof Rock ◽  
Soft Rock ◽  
Difficult Problem ◽  
Surrounding Rock ◽  
Ground Pressure ◽  
Geological Conditions ◽  
Floor Heave ◽  
Cable Force ◽  
Grouting Reinforcement ◽  
Roadway Support

Support of soft rock is a big challenge in all mines at home and abroad. Soft rock is of different kinds of rheological property for geological conditions, mine ground pressure and so on. It brings about really difficult problem to roadway support. In order to ensure safety application and prolong usage, shaft station need to be reinforced. Sight instrument was used to analyze broken conditions. The results show that the broken depth in roof rock is 5~6 m, and greater than 4 m in sidewalls. According to failure characters and sight results, we determine that rock of shaft station belongs to high geo-stress and jointed soft rock. On this basis, technology of grouting reinforcement combined with cable anchor support is carried out. Monitoring results of surface convergence and cable force show that bearing capacity of surrounding rock increases obviously, roadway contraction and floor heave are well controlled.

The Integrated Control Countermeasures on Floor Heave of Broken Soft Rock with High Ground Stress

2014 ◽  
Vol 875-877 ◽  
pp. 2259-2263 ◽  
Author(s):  
Yao Bin Li
Keyword(s):  
Integrated Control ◽  
Soft Rock ◽  
Mining Area ◽  
Stability Control ◽  
Surrounding Rock ◽  
Deep Well ◽  
Rock Stability ◽  
Geological Conditions ◽  
Floor Heave ◽  
Key Issues

The floor heave is one of the key issues of surrounding rock stability control during the deep well mining process. To solve the problem about floor heave occupying the most of roof and floor convergence deformation, the author analyzed the engineering geological conditions of broken surrounding rock and the floor heave features in PanEr Coal Mine East 2 mining area when it through the fault zone with high pressure. It pointed out that we should make full use of the reinforcement of the roof and laneway's side to limit the deformation of the floor, and make use of overbreak, prestressed anchor cable, bottom corner bolt, deep hole grouting and backfill as direct bottom control countermeasures.

scholarly journals A Case Study on Large Deformation Failure Mechanism of Coal given Chamber and Invention of a New Wall-Mounted Coal Bunker in Xiashijie Coal Mine with Soft, Swelling Floor Rock

2017 ◽  
Author(s):  
Xingkai Wang ◽  
Wenbing Xie ◽  
Shengguo Jing ◽  
Jianbiao Bai ◽  
Zhili Su
Keyword(s):  
Failure Mechanism ◽  
Coal Mine ◽  
Numerical Models ◽  
Surrounding Rock ◽  
Engineering Practice ◽  
Floor Rock ◽  
Geological Conditions ◽  
Floor Heave ◽  
The Stability ◽  
Bearing Structure

Serious damage caused by floor heave in the coal given chamber of a vertical coal bunker is one of the challenges faced in underground coal mines. Engineering practice shows that it is more difficult to maintain the coal given chamber (CGC) than a roadway. More importantly, repairing the CGC during mining practice will pose major safety risks and reduce production. Based on the case of the serious collapse that occurred in the bearing structure of the CGC at the lower part of the 214# coal bunker in Xiashijie mine, China, this work analysed (i) the main factors influencing floor heave and (ii) the failure mechanism of the load-bearing structure in the CGC using FLAC2D numerical models and expansion experiment. The analysis results indicate that: the floor heave, caused mainly by mine water, is the basic reason leading to the instability and repeated failure of the CGC in the 214# coal bunker. Then a new coal bunker, without building the CGC, is proposed and put into practice to replace the 214# coal bunker. The FLAC3D software program is adopted to establish the numerical model of the wall-mounted coal bunker (WMCB), and the stability of the rock surrounding the WMCB is simulated and analysed. The results show that: (1) the rock surrounding the sandstone segment is basically stable. (2) The surrounding rock in the coal seam segment, which moves into the inside of the bunker, is the main zone of deformation for the entire rock mass surrounding the bunker. Then the surrounding rock is controlled effectively by means of high-strength bolt–cable combined supporting technology. According to the geological conditions of the WMCB, the self-bearing system, which includes (i) H-steel beams, (ii) H-steel brackets, and (iii) self-locking anchor cables, is established and serves as a substitute for the CGC to transfer the whole weight of the bunker to stable surrounding rock. The stability of the new coal bunker has been verified by field testing, and the coal mine has gained economic benefit to a value of 158.026174 million RMB over three years. The new WMCB thus made production more effective and can provide helpful references for construction of vertical bunkers under similar geological conditions.

Reasonable Entry Layout of Lower Seam in Multi-Seam Mining Based on Numerical Simulation

2013 ◽  
Vol 295-298 ◽  
pp. 2980-2984
Author(s):  
Xiang Qian Wang ◽  
Da Fa Yin ◽  
Zhao Ning Gao ◽  
Qi Feng Zhao
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Coal Seam ◽  
Coal Mine ◽  
Abutment Pressure ◽  
Surrounding Rock ◽  
Geological Conditions ◽  
Seam Mining

Based on the geological conditions of 6# coal seam and 8# coal seam in Xieqiao Coal Mine, to determine reasonable entry layout of lower seam in multi-seam mining, alternate internal entry layout, alternate exterior entry layout and overlapping entry layout were put forward and simulated by FLAC3D. Then stress distribution and displacement characteristics of surrounding rock were analyzed in the three ways of entry layout, leading to the conclusion that alternate internal entry layout is a better choice for multi-seam mining, for which makes the entry located in stress reduce zone and reduces the influence of abutment pressure of upper coal seam mining to a certain extent,. And the mining practice of Xieqiao Coal Mine tested the results, which will offer a beneficial reference for entry layout with similar geological conditions in multi-seam mining.

Strength Assessments of Concrete-Filled Steel Tubular Support of Soft Rock Roadway

2013 ◽  
Vol 838-841 ◽  
pp. 1884-1890 ◽  
Author(s):  
Guang Long Qu ◽  
Yan Fa Gao ◽  
Liu Yang ◽  
Bin Jing Xu ◽  
Guo Lei Liu ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Coal Mine ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Flexural Performance ◽  
Laboratory Test Results ◽  
Different Types ◽  
Soft Rock Roadway ◽  
Core Concrete ◽  
Rock Roadway

Compared with I-shaped and U-shaped supports in soft rock roadway, concrete-filled steel tubular (CFST) support, as a new supporting form, has stronger bearing capacity with reasonable price. So it is becoming more and more popular in roadway supporting of coal mine in China. In this article, the surrounding rock in soft rock roadway was classified into three different types: hard rock in deep coal mine, soft surrounding rock, extremely soft surrounding rock. And, according to the characteristics of deformation failure of the CFST support and the surrounding rock in the industrial tests, three different strength assessments, including assessment of axial compressive strength, assessment of lateral flexural performance, assessment of hardening rate of core concrete, were proposed through mechanical analysis and laboratory tests for the three different types of the surrounding rock, respectively. Moreover, aimed to insufficient flexural strength of the support or low hardening rate of the core concrete in some of the roadway supporting, strengthening lateral flexural performance or making early strength concrete was necessary for the above unfavorable situations. The laboratory test results showed that the ultimate bearing capacity for the CFST support with φ194*8mm of steel tube reinforced by φ38mm round steel was 31% greater than that of the unreinforced one, 177% greater than that of the U-shaped one with equivalent weight per unit length.

Study on Stability for Intersection of Deep Soft Rock Roadway

2011 ◽  
Vol 243-249 ◽  
pp. 2666-2669
Author(s):  
Zhan Jin Li ◽  
Yang Zhang ◽  
Xue Li Zhao
Keyword(s):  
Coal Mine ◽  
Soft Rock ◽  
Intersection Problem ◽  
The Third ◽  
Geological Conditions ◽  
Control Stability ◽  
Soft Rock Roadway ◽  
Crossing Point ◽  
Coupling Support ◽  
Rock Roadway

With the depth increasing continuously, more complicated of geological conditions, will make intersection in deep soft rock roadway is very difficult to support. In order to solve the intersection problem of difficult to support, combined with the third levels of the Fifth Coal Mine of Hemei, the coupling supporting design—anchor-mesh-cable + truss to control stability of crossing point—is proposed. Based software of FLAC3D, simulate the program applicable in deep soft rock roadway intersection. Application results show that the coupling support technology of anchor-mesh-cable + truss can effectively control the deformation of intersection in deep soft rock roadway.

scholarly journals Analysis on Loose Circle of Surrounding Rock of Large Deformation Soft-Rock Tunnel

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Rui Wang ◽  
Yiyuan Liu ◽  
Xianghui Deng ◽  
Yu Zhang ◽  
Xiaodong Huang ◽  
...  
Keyword(s):  
Large Deformation ◽  
Theoretical Calculations ◽  
Rapid Development ◽  
Field Tests ◽  
Soft Rock ◽  
Strength Criterion ◽  
Surrounding Rock ◽  
Distribution Law ◽  
Geological Conditions ◽  
Rock Tunnel

With the rapid development of tunnel construction in China, deep buried and long tunnel projects are emerging in areas with complex engineering geological conditions and harsh environment, and thus large deformation of tunnels under conditions of high in situ stress and soft rock becomes increasingly prominent and endangers engineering safety. Therefore, it is of great significance to control the deformation and improve the stability of surrounding rock by analyzing the thickness and distribution law of loose circle according to the unique mechanical properties and failure mechanism of surrounding rock of large deformation soft-rock tunnel. Based on unified strength theory, this paper deduces the radius calculation formula of the loose circle by considering the influence of intermediate principal stress. Furthermore, the theoretical calculations and field tests of the loose circle in the typical sections of grade II and III deformation of Yuntunbao tunnel are carried out, and the thickness and distribution law of loose circle of surrounding rock of large deformation soft-rock tunnel is revealed. The results show that the formula based on the unified strength criterion is applicable for a large deformation tunnel in soft rock.

Analysis on the Mechanical Behavior of Pipe Roof and Rock Bolt of Shallow and Unsymmetrical Tunnel in Soft Rock

2012 ◽  
Vol 443-444 ◽  
pp. 267-271
Author(s):  
Xu Dong Cheng ◽  
Peng Ju Qin
Keyword(s):  
Soft Rock ◽  
Surrounding Rock ◽  
Mechanical Behaviors ◽  
Maximum Displacement ◽  
Tunnel Excavation ◽  
Finite Element Software ◽  
Highway Tunnel ◽  
Geological Conditions ◽  
The Impact ◽  
Rock Strata

In this paper, the mechanical behaviors of pipe roof and bolt of shallow and unsymmetrical tunnel in soft rock are analyzed. Through the finite element software Phase2.0, combined with the geological conditions that construction site often appear, the mechanical behaviors of pipe roof and bolt and surrounding rock in the process of horseshoe highway tunnel construction in the condition that surface is soft rock and underground for the bedrock are analyzed. Research results show that: after tunnel excavation in soft rock, surrounding rock near the tunnel is easy to suffer soft-rock large deformation even failure, which needs to timely support；Due to the impact of the unsymmetrical tunnel, the mechanical behaviors of surrounding rock are unsymmetrical, such as the maximum displacement of tunnel around 0.4 m distant from apex of arch ring, the stress is asymmetrical on both sides of the tunnel arch ring etc; In addition, pipe roof can effectively prevent from the displacement of soft rock strata, improve tunnel strength factor, reduce the plastic zone of surrounding rock. This paper provides theoretical basis for the design of pipe roof and bolt.

Development and Application of Complementary Support Technology under the Condition of Weak and Broken Surrounding Rocks

2011 ◽  
Vol 243-249 ◽  
pp. 3389-3398
Author(s):  
Hong Wei Wang ◽  
Yao Dong Jiang ◽  
Jie Zhu ◽  
Xian Tao Zeng ◽  
Peng Fei Jiang ◽  
...  
Keyword(s):  
Coal Mine ◽  
Rock Strength ◽  
High Stress ◽  
Surrounding Rock ◽  
Deep Mining ◽  
Induced Stress ◽  
Geological Conditions ◽  
Support Force ◽  
Support Element ◽  
Yielding Support

The support of surrounding rock under the condition of deep mining has significant challenges due to high stress and low rock strength environment. Using the method of strengthening broken rock, reinforcing support force and releasing the mine-induced stress, this study has pointed out the complementary support technology which is based on the support using bolt-wire-shotcrete and is combined with steel arched yielding support. For the purpose of permanent support, the complementary support technology could combine the each support element and adequately take advantage of load-caring capacity of surrounding rock. The monitoring data of Xiaokang coal mine, Muchengjian coal mine and Yangquhe coal mine indicate that, for the various geological conditions, complementary support system has provided powerful support force to resist large deformation of weak and broken surrounding rock. It is proved that this type of support technology could reduce the mine-induced stress as well and has economical significance.

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