scholarly journals Numerical Simulation Research on Distribution Characteristics of Overlying Rock Stress Field in Floor Roadway

2021 ◽  
Vol 257 ◽  
pp. 03024
Author(s):  
Zhonghua Wang
Keyword(s):  
Stress Field ◽  
Field Distribution ◽  
Theoretical Basis ◽  
Surrounding Rock ◽  
Horizontal Distance ◽  
Distribution Characteristics ◽  
Rock Stress ◽  
Simulation Research ◽  
Location Selection ◽  
Coal Roadway

In order to explore the distribution characteristics of the overlying rock stress field in the floor roadway at different locations, FLAC3D software was used to simulate and analyze the surrounding rock directly above the floor roadway and the surrounding rock within 15m on both sides of the floor roadway when the distance between the floor roadway and the coal roadway and the horizontal distance were changed. The stress field distribution characteristics are obtained, and the stress field distribution characteristics of different areas directly above and on both sides of the floor roadway are obtained, which provides a theoretical basis for the location selection and support of the floor roadway.

scholarly journals An Experimental Research on Surrounding Rock Unloading during Solid Coal Roadway Excavation

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Hongjun Guo ◽  
Ming Ji ◽  
Dapeng Liu ◽  
Mengxi Liu ◽  
Gaofeng Li ◽  
...  
Keyword(s):  
Energy Storage ◽  
Deformation Energy ◽  
Surrounding Rock ◽  
Dissipated Energy ◽  
Rock Stress ◽  
Deformation And Failure ◽  
Coal Roadway ◽  
Solid Coal ◽  
Unloading Rate ◽  
Surrounding Rock Stress

In order to further explore the deformation and failure essence of the deep coal body, based on the characteristics of surrounding rock stress adjustment before and after solid coal roadway excavation, an experiment of unloading confining pressure and loading axial pressure of the coal body was designed and conducted in this study. Based on test results, the failure mechanics and energy characteristics of the coal body were analyzed through experiments. Rapid unloading is considered a key factor contributing to lateral deformation and expansion failure, which exacerbates the deterioration of coal body and reduces the deformation energy storage capacity of coal. On the other hand, the larger loading rate tends to shorten the accumulation time of microcracks and cause damage to the coal body, resulting in strengthening the coal body and improving energy storage. Under the circumstance that the coal body is destroyed, the conversion rates of the internal deformation energy and dissipated energy are more significantly affected by unloading rate. The increasing unloading rate and rapid decreases in the conversion rate of deformation energy make the coal body more vulnerable to damage. Under the same stress conditions, the excavation unloading is more likely to deform, destroy, or even throw the coal than the experiment unloading. In order to reduce or avoid the occurrence of deep roadway excavation accidents, the understanding of the excavation unloading including possible influencing factors and the monitoring of the surrounding rock stress and energy during the excavation disturbance should be strengthened. It can be used as the basis for studying the mechanism of deformation and failure of coal and rock and dynamic disasters in deep mines, as well as the prediction, early warning, prevention, and control of related dynamic disasters.

scholarly journals Parameter optimization of anti crystallization flocking drainage pipe based on flow field distribution characteristics

2021 ◽  
Vol 25 (6 Part A) ◽  
pp. 4091-4098
Author(s):  
Shiyang Liu ◽  
Kun Xiang ◽  
Feng Gao ◽  
Xuefu Zhang ◽  
Yun Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Velocity Distribution ◽  
Flow Velocity ◽  
Field Distribution ◽  
Parameter Optimization ◽  
Theoretical Basis ◽  
Longitudinal Direction ◽  
Distribution Characteristics ◽  
Drainage Pipe

The crystal plugging of tunnel drainage pipe seriously affects the safe and normal use of the tunnel. In order to obtain the mechanism of flocking drainage pipe anti crystal plugging based on the characteristics of flow field distribution, numerical simulation was used to optimize the parameters of flocking drainage pipe. The results show that: with the existence of fluff, the velocity in the lower part of the drainage pipe decreases by about 50%, and the velocity in the upper part increases by about 25~50%. With the increase of the length of fluff, the velocity funnel between fluffs gradually increases, the velocity distribution at the bottom of the funnel is basically unchanged, and the velocity in the upper part gradually increases. The velocity in the upper part of the flocked drainage pipe fluctuates above the fluff to a certain extent. The flow velocity in the lower part of the drainage pipe forms a flow velocity ladder in the longitudinal direction of the villus, and the width of the ladder is about 2/3 of the longitudinal spacing of the villus. The optimized parameters of 3-D flow field of flocked drainage pipe are helpful to the further improvement of indoor test, and provide theoretical basis for the mechanism of preventing crystal blockage of flocked drainage pipe.

scholarly journals Application of Improved Single-Hole Superposition Theory in Nonequal Cross-Section Tunnel Intersection

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Ning Liu ◽  
Yi-Xiong Huang ◽  
Wei Cai ◽  
Kun Chen
Keyword(s):  
Cross Section ◽  
Surrounding Rock ◽  
Horizontal Distance ◽  
Rock Stress ◽  
Safety Level ◽  
Small Section ◽  
Single Hole ◽  
Triangular Area ◽  
The Impact ◽  
Surrounding Rock Stress

With the excavation towards the intersecting tunnels’ direction, the impact on the surrounding rock stress between the two tunnels will gradually decrease, but how it decreased is not clear. At present, engineers often directly superimpose the stress in the triangular area of the crossing tunnel when calculating the stress in this area (single-hole superposition theory). The theory is also used as the main theory to consider the surrounding rock stress for support which is difficult to explain the situation of nonuniform cross-section centers not in the same plane. The safety level of support is mainly determined by construction experience which is unable to determine how to adjust the support level with the increase in the horizontal distance of intersecting tunnel, causing the insufficient utilization of materials. This paper derives theoretically the stress calculation of the triangular area of circular cross tunnels with different cross sections and analyzes the surrounding rock stress law of the intersecting tunnels triangular area from different cross-section dimensions (the difference in diameter between the two tunnels is twice, 3 times, and 4 times) and different intersection angles. And the results show that, compared with the case of equal tunnel diameters, the stress influence area of the surrounding rock in the triangle area mainly expands to the side of the small section with the increase of the cross-section difference of the intersecting tunnels; the dangerous area of the surrounding rock in the triangle area moves vertically to the small section; the safest condition is the two tunnels with 90° intersecting angle. The theoretical calculation model of this paper is verified by the previous research results.

scholarly journals Numerical Simulation Research on the Stability of Urban Underground Interchange Tunnel Group

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Shiding Cao ◽  
Shusen Huo ◽  
Aipeng Guo ◽  
Ke Qin ◽  
Yongli Xie ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Surrounding Rock ◽  
Distribution Characteristics ◽  
Large Area ◽  
Group Project ◽  
Simulation Research ◽  
Joint Construction ◽  
Tunnel Section ◽  
The Stability ◽  
The Right

Highway tunnel group has the characteristics of large span and small spacing, and the load distribution characteristics of surrounding rock between each tunnel section are complex. Based on geological prospecting data and numerical analysis software, the stress distribution characteristics along the characteristic section and the profile of the tunnel group were obtained. Taking Shenzhen Nanlong complex interchange tunnel group project as an example, the results show that (1) the excavation area of Qiaocheng main tunnel gradient section is large, and the grade of surrounding rock is poor, which leads to the phenomenon of large-area stress concentration on the right wall of this section. (2) The tunnels in the joint construction section of the tunnel group belong to the stress concentration area, and the influence of the right line excavation of Qiaocheng on the stability of the main tunnel of the right line of Baopeng is greater than that of the main tunnel of the left line of Baopeng. (3) The stress concentration of surrounding rock in the intersection section between the main tunnel and the ramp is caused by the too small distance between the main tunnel and the ramp of Baopeng. (4) The distance between the partitions in the K3 + 240 multiarch section of Qiaocheng is an important factor affecting the stability of the surrounding rock of the cave.

scholarly journals Impact of In Situ Stress Distribution Characteristics on Jointed Surrounding Rock Mass Stability of an Underground Cavern near a Hillslope Surface

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Bangxiang Li ◽  
Yong Li ◽  
Weishen Zhu ◽  
Chao Li ◽  
Zhenxing Dong
Keyword(s):  
Rock Mass ◽  
Stress Distribution ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
Horizontal Distance ◽  
Distribution Characteristics ◽  
Slope Surface ◽  
Rock Mass Stability ◽  
Underground Cavern

In this paper, a series of numerical simulations are performed to analyze the in situ stress distribution characteristics of the rock mass near different slope angles hillslope surfaces, which are subjected to the vertical gravity stress and different horizontal lateral stresses and the influence which the in situ stress distribution characteristics of 45° hillslope to the integral stability of surrounding rock mass when an underground cavern is excavated considering three different horizontal distances from the underground cavern to the slope surface. It can be concluded from the numerical results that different slope angles and horizontal lateral stresses have a strong impact on the in situ stress distribution and the integral surrounding rock mass stability of the underground cavern when the horizontal distance from the underground cavern to the slope surface is approximately 100 m to 200 m. The relevant results would provide some important constructive suggestions to the engineering site selection and optimization of large-scale underground caverns in hydropower stations.

scholarly journals Stress Field Distribution and Deformation Law of Large Deformation Tunnel Excavation in Soft Rock Mass

2019 ◽  
Vol 9 (5) ◽  
pp. 865 ◽  
Author(s):  
Heng Zhang ◽  
Liang Chen ◽  
Yimo Zhu ◽  
Zelin Zhou ◽  
Shougen Chen
Keyword(s):  
Stress Field ◽  
Large Deformation ◽  
Field Distribution ◽  
Rational Design ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Economic Losses ◽  
Tunnel Excavation ◽  
Tunnel Support ◽  
Deformation Law

The problem of large deformation is very prominent in deep-buried tunnel excavation in soft rock, which brings serious potential safety hazards and economic losses to projects. Knowledge of the stress field distribution and deformation law is the key to ensuring rational design and safe construction in large deformation tunnels of soft rock. As described in this paper, theoretical analysis, numerical simulation and field monitoring were employed to investigate the surrounding rock stress and displacement state in the Dongsong hydropower station in Sichuan Province, China. The results show that the short-bench construction method can effectively control the deformation of surrounding rock and range of the plastic zone. In order to reserve enough working space, the optimum bench length in the actual construction was 10 to 14 m. The peripheral displacement and plastic radius decreased with the increase of tunnel support strength and the advance of supporting time. The displacement can be effectively controlled by applying the second lining in time at a position about twice the diameter of the hole (16 m) from the working face. A reasonable reserved deformation should be adopted to avoid secondary expanding excavation. The values of different positions in the tunnel laterally and longitudinally may be different, and adjustments are needed according to the actual situation.

scholarly journals Numerical Simulation of the Supporting Effect of Anchor Rods on Layered and Nonlayered Roof Rocks

2020 ◽  
Vol 2020 ◽  
pp. 1-14 ◽  
Author(s):  
Chao Yuan ◽  
Lei Fan ◽  
Jian-feng Cui ◽  
Wei-jun Wang
Keyword(s):  
Stress Field ◽  
Compressive Stress ◽  
Displacement Field ◽  
Surrounding Rock ◽  
Rock Stress ◽  
Deformation Control ◽  
Original Rock ◽  
Supporting Effect ◽  
Roof Rocks ◽  
Bolt Support

In order to clarify the influence of anchor bolts on the supporting effect of the layered weak roof and surrounding rock of nonlayered roof with good integrity, the mechanical model of the roadway with nonlayered homogeneous roof and layered weak roof was established using FLAC3D. The distribution characteristics of the stress field and the displacement field of the bolt support are analyzed, and the supporting effect of the bolt on the roof of two types of roadways is studied. The research results show that when the original rock stress is not considered, the bolt support shows obvious tensile, compressive stress areas and positive and negative displacement areas in the surrounding rock of the roof of the roadway; when the original rock stress is taken into account, the tensile and compressive stress zones and the positive and negative displacement zones of the anchor support in the surrounding rock of the roof plate disappear obviously. The effect of the bolt support on the stress field and plastic area of the surrounding rock of the two types of roadway roof is not obvious. However, it has a significant effect on suppressing discontinuous deformation such as delamination and sliding between layered roof rocks. The delamination phenomenon between rock layers disappeared obviously, and the range of each numerical curve of the displacement field of the surrounding rock in the anchoring area was significantly reduced. However, the effect of the anchor support on continuous deformation control such as elastoplastic deformation of roof rock of nonlayered roadway is very limited. There is almost no change in the displacement field curve in the depth of the roof-surrounding rock. Only the shallow surrounding rock displacement field curve range has decreased.

scholarly journals Study on Deformation Mechanism and Supporting Countermeasures of Compound Roofs in Loose and Weak Coal Roadways

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jianfeng Cui ◽  
Weijun Wang ◽  
Chao Yuan ◽  
Liming Cao ◽  
Yuning Guo ◽  
...  
Keyword(s):  
Field Application ◽  
Surrounding Rock ◽  
Main Body ◽  
Vicious Cycle ◽  
Rock Stress ◽  
Anchor Cable ◽  
Coal Roadway ◽  
Safe Control ◽  
Roadway Support ◽  
Surrounding Rock Stress

This paper considers the 333 return airway of the Gaokeng Coal Mine to analyze the deformation characteristics and failure mechanism of the surrounding rock of the composite roof for a loose and weak coal roadway. The reasons for the large deformation are explored and the superiority of the prestressed truss and anchor rope is compared to ordinary anchor cables from the perspective of mechanics to propose a targeted coal roadway support method. Sinking of the composite roof in the coal roadway is accompanied with a release and transfer of the surrounding rock stress. The pressure of the composite roof transfers to the roadway sides and intensifies the fracture process of the coal body. As a result, the ability to support the composite roof is weakened, and it further bends and sinks to form a vicious cycle that repeats itself. Therefore, the support of the composite roof in the coal roadway should consider the roof, roadway sides, and floor as a single unit to achieve the support goal of reinforcing the roadway sides and roof. Based on the above analysis, a comprehensive control technology with a truss and anchor rope is proposed as the main body and a bolt + anchor cable + metal network as the auxiliary. This technology can improve the integral bearing capacity of the composite roof, strengthen the roadway side structures, and reinforce the roadway sides and roof. Numerical simulation and field application results show that the support scheme can effectively realize safe control of the composite roof in coal roadways.

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