scholarly journals Instability Mechanism and Key Control Technology of Deep Soft Rock Roadway under Long-Term Water Immersion

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Wei Jing ◽  
Xu Wang ◽  
Pengwei Hao ◽  
Laiwang Jing ◽  
Weipei Xue

More and more attention has been paid to the supporting problem of deep soft rock roadway floor with long-term water immersion in recent years. However, the existing soft rock roadway support technology rarely takes into account the influence of the immersion softening phenomenon of the roadway floor and the self-supporting structure characteristics of the surrounding rock on the stability of the surrounding rock at the same time, and the influence of the creep characteristics of rock on the deformation zone of the surrounding rock requires further research on the nature and division of the self-supporting structure of the surrounding rock. In response to the issues mentioned, based on the loading and unloading properties of the surrounding rock of the soft rock roadway, a new concept of the internal and external self-bearing structure was proposed. The fact of water-immersed mudstone softening in the soft rock roadway floor was revealed through the field practice, and the shape of the internal and external bearing structure was determined based on the in situ monitoring results. Then, the instability mechanism of the internal and external self-bearing structure of the surrounding rock was analyzed, the position of the critical control point was calculated, and the key control technology based on the method of controlling floor heave by using double-row anchor cables to control the deformation of the roadway sides was put forward. Finally, the field industrial test showed that this support technology can effectively control the deformation and failure of soft rock roadway in the case of water immersion on the floor. This work can provide a technical reference for similar roadway support designs.

2019 ◽  
Vol 11 (7) ◽  
pp. 1892 ◽  
Author(s):  
Dongdong Qin ◽  
Xufeng Wang ◽  
Dongsheng Zhang ◽  
Xuyang Chen

Providing support for deep soft rock roadways under dynamic pressure is a major technical challenge. In this study, the distribution characteristics of surrounding rock-bearing structure of such roadways were systematically examined using theoretical analysis and numerical simulation. Based on the control effect of different support methods on the surrounding rock-bearing structure; a reinforcement scheme for deep dynamic soft rock roadway was proposed and applied. The results indicate that: (1) by increasing the supporting strength of the internal bearing structure, cohesion, and internal friction angle of the surrounding rock, and by reducing the influence of mining, making the external bearing structure close to the roadway and reducing the thickness of the bearing structure, can improve the bearing capacity of the shallow surrounding rock in the roadway; (2) under the conditions of dynamic load and creep of the surrounding rock; the deformation of the rock increases significantly; external bearing structure is far away from the roadway, and thickness of the bearing structure increases; anchor cable support and floor pressure relief effect better control over the roof and the roadside deformation and floor heave, respectively; and the thickness of the corresponding external bearing structure is reduced by 30.84% and 41.50%, respectively; and (3) based on the application, the zonal reinforcement scheme of “fix cable to shed, floor pressure relief, deep-shallow composite grouting” is proposed and put into practice, with good results. The results of this study can provide theoretical support and reference for the determination of supporting parameters in deep roadways.


2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Shuai Guo ◽  
Xun-Guo Zhu ◽  
Xun Liu ◽  
Hong-Fei Duan

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.


2013 ◽  
Vol 734-737 ◽  
pp. 606-613 ◽  
Author(s):  
Feng Jie Zhang ◽  
Pan Liu ◽  
Xiang Rui Meng ◽  
Zhao Ning Gao

the stabilization of the rock support structure is the key to the safety and stability in the deep soft rock roadway, According to the bearing characteristics of surrounding rock, this paper puts forward the definition of double bearing structure, using FLAC3D numerical simulation software and theory of mechanics analyses Bearing Mechanism of Double Support Structure. The research shows: Excavation of soft rock roadway, the vertical strain and horizontal strain of the surrounding rock of roadway has wave, the surround rock appearing obvious deformation and displacement of roadway roof and floor in 3M, and the roadside appearing extrusion failure in the range of 2m. The roadway is more stable as the figure of the plastic radius is smaller, the same to outer bearing structure’s boundary and the width of outer bearing structure and plastic zone.


2012 ◽  
Vol 256-259 ◽  
pp. 892-895
Author(s):  
Yu Cheng Zhao ◽  
Dan Feng Lu ◽  
Ya Bin Zhen

With the increase of the mining depth, the surrounding rock of roadways shows the characteristics of soft rock that the stress increase, poor rock cementation, broken loose, a significant expansion, creep deformation, etc. Deep roadways mainly use the combination of active and passive supporting method, U-type shed is widely used in the roadway support and becomes gradually the main supporting form. This paper studies mechanical properties of different arched U- type sheds, then compares the stress distribution and the displacement change. According to the result of simulation and optimization, it is seen that the deformation trend is regular with the angle change, and when θ=30°, the U- type shed is better in the roadway support. The conclusion can provide some theoretical guidance for the deep or soft rock roadway support.


2012 ◽  
Vol 594-597 ◽  
pp. 616-620
Author(s):  
Lian Wei Ren ◽  
Guang Yong Wang ◽  
Long Wang

Because of the existence of high stress in the surrounding rock of deep roadway, the physical and mechanical properties of the surrounding rock to change, and the surrounding rock stress distribution is very different from the shallow, so the way of shallow roadway support is not suitable for deep roadway. Deep soft-rock roadway support is a complex systems engineering, it should consider the different geological conditions, roadway scope of application, construction technology conditions, construction period and the cost and other factors to determine the optimal combined support program, if the special geological conditions encountered in the construction, it should be timely to improve the supporting program to meet the construction safety and ensure the quality. This paper is based on the characteristics of deep roadway support, sums up the combined support form in the project, researches and analyzes the combined support technology, and explores how to use suitable combined support form in deep roadway.


Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4357
Author(s):  
Qingxian Huang ◽  
Xufeng Wang ◽  
Xuyang Chen ◽  
Dongdong Qin ◽  
Zechao Chang

Pingdingshan mining area is one of the typical deep mining areas in China, and most of the mines in this area are troubled by the difficulties of the deep-soft-rock roadway support. Based on the concept of synergistic interactions of the interior and exterior bearing structure of the surrounding rock and, considering the specific geological conditions of the research site, we establish the mechanical model of the interior and exterior bearing structure of the roadway. Based on numerical simulation, we reveal the influence of main factors, such as support strength and mechanical characteristics, of surrounding rock on the distribution and evolution of the interior and exterior bearing structure. We found that increasing the support strength and mechanical parameters of surrounding rock can make the exterior bearing structure close to the roadway enhance the bearing characteristics of the interior and exterior bearing structure and improve the roadway stability. The distribution characteristics of the interior and exterior bearing structure of the roadway under six different support strengths and six different grouting parameters were systematically investigated by field measurements. According to the field test results, an effective strategy for controlling the deep-soft-rock roadway is proposed, which provides a good reference for surrounding rock control of the deep-soft-rock roadway in the Pingdingshan mining area and mines with similar mining conditions.


2021 ◽  
Author(s):  
Minghui Ma ◽  
Qifeng Guo ◽  
Jiliang Pan

Abstract Through theoretical calculation, the stress and deformation of surrounding rock can be analyzed, which can provide guidance for support design and optimization of soft rock roadway. In this paper, theoretical solutions for both the optimal support pressure and the allowable maximum displacement of surrounding rock are derived based on the Drucker-Prager (DP) yield criteria and the steady creep criterion expressed by the third invariant of deviator stress. The DP criteria with different parameters are compared and analyzed by an engineering example. Then, based on the calculation results, the effects of long-term strength, cohesion and internal friction angle of soft rock on the maximum plastic zone radius and allowable maximum displacement of roadway are discussed. The results show that the optimal support solution of soft rock roadway based on DP criteria can not only reflect the intermediate principal stress reasonably, but also can compare and discuss the influence of different DP criteria on the calculation results. The higher the long-term strength of the roadway surrounding rock is, the smaller the optimal support force is and the larger the allowable maximum displacement is. When the calculated long-term strength of soft rock can ensure that the deformation of the roadway does not exceed the allowable maximum displacement, the roadway can maintain long-term stability without support. With the increase of the cohesion or internal friction angle of soft rock, the radius of plastic zone decreases gradually, and the allowable maximum displacement is reduced by degrees. Through grouting and other means to improve the strength of surrounding rock can effectively reduce the roadway deformation and save support costs.


2013 ◽  
Vol 838-841 ◽  
pp. 1884-1890 ◽  
Author(s):  
Guang Long Qu ◽  
Yan Fa Gao ◽  
Liu Yang ◽  
Bin Jing Xu ◽  
Guo Lei Liu ◽  
...  

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.


2011 ◽  
Vol 90-93 ◽  
pp. 1956-1959 ◽  
Author(s):  
Zhi Lin Dun ◽  
Da Shuai Ren ◽  
Lian Wei Ren

With the increasement of mining depth, the strata behavior of the roadway is obvious. As the stress of surrounding rock increases, the bottom of the soft rock roadway becomes deformed easily compressed by its top rock and two sides rock, which leads to the occurrence of the pucking and roadway destruction. Aiming the air inlet roadway destruction phenomenon of -450th level powder magazine in Hebi Zhongtai Mining Co.Ltd, the geological condition and the mechanism of the roadway failure are analysed comprehensively, and the bolt-grout supporting method is also proposed in this paper. At last, the deformation and heaving floor are controlled effectively which is proved by the field monitoring results.


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