Deformation Of Roadway Surrounding Rock Research Articles

A study on the reasonable width of narrow coal pillars in the section of hard primary roof hewing along the air excavation roadway

AbstractAiming at the reasonable width of the narrow coal pillar of a fully mechanized caving face and the safety support of roadway, taking the coal pillar in the section between 110503 and 110505 face of the Yushuling Coal mine as the research background, a model of the hard basic roof fracture structure of fully mechanized caving face is established through theoretical analysis, and the roadway with narrow coal pillar is analyzed mechanically. Combined with the geological conditions of the working face, it is concluded that the low‐stress area is less than 3.29 m. When the internal stress field of the low‐stress environment is considered in the roadway layout, the influence of mining and the essential roof hardness should be considered. The reasonable size of the narrow coal pillar is 3 ~ 6 m, thinking that the load borne by the coal pillar is less than the ultimate strength of the coal pillar. The limit equilibrium theory calculates that the reasonable width of a coal pillar is at least 4 m. The stress and displacement of coal pillars with different widths of 3, 4, 5 and 6 m are analyzed by numerical simulation, and the 4 m narrow coal pillars are simulated and verified. Field industrial tests show that coal pillar and roadway surrounding rock deformation are small under asymmetric surrounding rock control. The research results have been successfully applied to engineering practice and can provide a reference for the research method of narrow coal pillar width under a hard basic roof.

Research on Stability Control Technology of Mining Roadway Based on Energy Transformation

The process of roadway surrounding rock deformation and instability is always accompanied by energy changes, and the energy transformation of surrounding rock directly drives its deformation and failure. In order to realize the stability control of mining roadway, the distribution of elastic strain energy and plastic strain energy of surrounding rock was analyzed by using FLAC3D numerical simulation software on the basis of the energy transformation law of sandstone under different confining pressures revealed by indoor triaxial compression test. Based on this, combined with the energy transformation, the principle of roadway surrounding rock stability control technology is proposed. One is to reduce the elastic strain energy of surrounding rock, that is, by increasing the extension of support body, part of the roadway energy is transferred to the support body, so as to improve the energy release of surrounding rock, or by optimizing the layout of roadway to reduce the energy accumulation of surrounding rock. The second is to increase the plastic strain energy of surrounding rock, that is, to increase the energy dissipation of surrounding rock by setting weak structure. The above research results are applied to the surrounding rock control of the right second transport roadway in the 91st coal of Xinjian coal mine. After the optimization of support measures, the roadway surface displacement and its increase rate decreased significantly, roof subsidence decreased from 247 mm to 62 mm, floor heave decreased from 120 mm to 26 mm, and the right rib shrinkage decreased from 292 mm to 94 mm, that is, the floor heave control effect was particularly obvious. The deformation of surrounding rock gradually stabilized after 45 days.

Theoretical Study on the Mechanism of Asymmetrical Large Deformation of Heading Roadway Facing Mining

The problem of asymmetric large deformation of surrounding rock of heading roadways is prominent due to the superposition of mining stress in the mining intersection area. Therefore, on the basis of the background of 18,106 tailentry in the Xiegou Coal Mine, this paper establishes a mechanical model of surrounding rock deformation of mining roadways under the effect of advanced abutment pressure. In the model, we deduce the theoretical calculation formula of roadway full-section deformation and discuss the influence factors of roadway surrounding rock deformation. Accordingly, the deformation mechanism of surrounding rock of mining roadways and the engineering suggestions and measures are revealed. The main results and finding are threefold. Firstly, the increase of the stress concentration factor of the coal pillar rib and the increase of the width of the failure zone are the fundamental reasons leading to the aggravation of the surrounding rock deformation on the side of the coal pillar in the heading roadway. Secondly, the deformation of the coal pillar rib increases with the increase of stress concentration factor and decreases with the increase of coal cohesion, internal friction angle, elastic modulus, and roadway rib support resistance. Additionally, the deformation of the roadway roof and floor decreases with the increase of roadway rib support resistance and is inversely proportional to the cubic power of rock beam thickness and elastic modulus. The deformation rate of the roadway roof and floor increases with the increase of vertical stress concentration factor of the coal pillar rib, and the maximum deformation position shifts to the side of the coal pillar. Therefore, increasing the strength and stiffness of the roadway surrounding rock and the supporting resistance of surrounding rock can reduce the deformation of roadway surrounding rock and the influence of advanced abutment pressure on roadway deformation. In the end, the rationality and feasibility of the theoretical analysis is verified through an engineering example. Under the influence of advanced abutment pressure, the deformation of roadway floor heave is the most severe, the asymmetrical deformation on both sides of the roadway is remarkable, and the deformation of coal pillar side is about twice that of solid coal side.

Study on Failure Characteristics and Reasonable Mining Parameters of Upward Mining of Integrated Coal Mine

In order to avoid the problem of repeated repair of roadways in the upper mining area of upward mining in the integrated mine, taking the roadways in the 302 mining area of Shancheng Coal Mine as the research object, the failure characteristics of overlying strata and the evolution characteristics of roadway plastic zone in the mining process of underlying coal seam were studied by combining theoretical analysis, numerical simulation, and engineering measurement. The influence law of underlying coal seam mining on the integrity of 3# coal seam and the stability of roadways in the 302 mining area was revealed, and the repair opportunity of roadways in the upper coal seam and the reasonable position of open-off cut in the lower coal seam working face were determined. The research shows that due to the influence of the mining of the working face in the underlying coal seam, the plastic failure of the overlying strata is serious during the upward mining of Shancheng Coal Mine, but there is no step dislocation, but the overall subsidence is presented. The plastic zone range of roadway in 302 mining area first increases and then tends to be stable with the mining of 97308 working face in underlying coal seam, and the roadway repair should be carried out after 280 m advance of 97308 working face. Based on the coordination between the influence of the cutting position of the underlying coal seam on the variation characteristics of the plastic zone of the upper roadway and the saving of coal resources, it is determined that the cutting position of the underlying 153308 working face is advanced to 340 m. The field engineering application shows that the deformation of roadway surrounding rock meets the production requirements by implementing the above mining parameters, and the rerepair of roadway surrounding rock deformation in 302 mining area of 3# coal seam is avoided.

Influence of anchorage length and pretension on the working resistance of rock bolt based on its tensile characteristics

In coal mining roadway support design, the working resistance of the rock bolt is the key factor affecting its maximum support load. Effective improvement of the working resistance is of great significance to roadway support. Based on the rock bolt’s tensile characteristics and the mining roadway surrounding rock deformation, a mechanical model for calculating the working resistance of the rock bolt was established and solved. Taking the mining roadway of the 17102 (3) working face at the Panji No. 3 Coal Mine of China as a research site, with a quadrilateral section roadway, the influence of pretension and anchorage length on the working resistance of high-strength and ordinary rock bolts in the middle and corner of the roadway is studied. The results show that when the bolt is in the elastic stage, increasing the pretension and anchorage length can effectively improve the working resistance. When the bolt is in the yield and strain-strengthening stages, increasing the pretension and anchorage length cannot effectively improve the working resistance. The influence of pretension and anchorage length on the ordinary and high-strength bolts is similar. The ordinary bolt’s working resistance is approximately 25 kN less than that of the high-strength bolt. When pretension and anchorage length are considered separately, the best pretensions of the high-strength bolt in the middle of the roadway side and the roadway corner are 41.55 and 104.26 kN, respectively, and the best anchorage lengths are 1.54 and 2.12 m, respectively. The best anchorage length of the ordinary bolt is the same as that of the high-strength bolt, and the best pretension for the ordinary bolt in the middle of the roadway side and at the roadway corner is 33.51 and 85.12 kN, respectively. The research results can provide a theoretical basis for supporting the design of quadrilateral mining roadways.

Evolution Mechanism and Stability Analysis of Roof Deflection of Composite Structure Roadway Under Dynamic Load Disturbance

The lithology of the roof of the mining roadway is compound and the thickness of each layer varies considerably, and it is disturbed by dynamic load all the year round. The above factors has caused a huge difference in the stability of the roadway surrounding rock. Taking the 11,020 lower tunnel of a mine in Henan Province as the engineering geological background, using on-site investigation, formula derivation, numerical simulation and other methods, the composite roof roadway model group was established to study the deflection evolution characteristics of the surrounding rock under dynamic load disturbance, and summarize the plastic zone of the surrounding rock of the roadway Deformation and evolution of roof surrounding rock to evaluate the stability of surrounding rock with different roof structures. The research results show that the change of the roof surrounding rock structure will also lead to the change of the center deflection of the roadway roof. Therefore, the center deflection of the surrounding rock of various roof composite structures is different, and the deflection is the most direct indicator of the stability of the surrounding rock. The center deflection (\(\omega_{0}\)) of the soft rock type is the largest, the center deflection (\(\omega_{0}\))of the upper soft and the lower hard type, and the soft and hard type is larger, and the soft and hard progressive type, thin, hard and thick soft type (\(\omega_{0}\)) is the smallest, and the dynamic load The relationship between the magnitude of deflection before and after the disturbance is consistent. By constructing a composite roof roadway numerical model group, using the plastic failure zone of the roadway as the evaluation standard, the surrounding rock stability is evaluated and divided, and then the cross-point field measurement method is used to verify the stability of the surrounding rock on the roof of different composite structures. And the development of composite roof roadway surrounding rock deformation and failure mechanism and numerical simulation method has important theoretical significance and practical value for the analysis and control of composite roof roadway surrounding rock stability.

Instability Analysis and Reinforcement Support Technology of Coal-Rock Interbed Roadway in Gaojiazhuang Coal Mine

In order to effectively solve a series of problems such as the difficulty of coal and rock interbed roadway support in Gaojiazhuang Coal Mine and get a scientific and reasonable optimization scheme of surrounding rock support, theoretical analysis, numerical simulation, ultrasonic detection, field-effect test, and other means are adopted to analyze the instability of coal and rock interbed roadway. The results show that the interbedded roadway has weak interbedded cementation, and its ore pressure is more intense due to the influence of its interbedded weak structural plane. Based on Mohr’s strength envelope principle, it is proposed that horizontal stress is the main factor that causes a wide range of shear displacement, penetration crack, and surrounding rock failure of the roof of this kind of roadway. Through the finite element numerical simulation analysis, the deformation and failure law, stress distribution characteristics, and failure area distribution characteristics of coal and rock interbedding roadway surrounding rock are theoretically revealed, and the control effect of different support schemes on roadway surrounding rock deformation is greatly different. Based on the ultrasonic detection technology, it is proved that the roadway side failure has strong zoning characteristics, and the failure range and stress distribution range of the surrounding rock of the belt roadway in the 2103 working face of Gaojiazhuang Coal Mine are detected. Finally, the coupling strengthening support scheme combining prestressed anchor cable and bolt is proposed. The engineering application and the observation of surrounding rock deformation show that the reinforced support technology can effectively enhance the stability of the surrounding rock of the interbed roadway in Gaojiazhuang Coal Mine, and it has a good reference for the surrounding rock conditions of this kind of roadway.

Support Technology of Long Bolt in Roadway under Crushing Condition

In order to solve the problem that the roadway roof is large and easy to collapse under crushing conditions. Test shows that: Under the crushing condition, a considerable part of roadway surrounding rock deformation is in a given deformation state. The control effect of support resistance on surrounding rock deformation is limited at the level of existing technology. In this kind of roadway support, the deformation method of anchor cable high rigidity support should be abandoned. It is changed to adopt the long bolt with high elongation to adapt to the deformation of surrounding rock, and continue to provide high support resistance to prevent loose rock caving caused by roof collapse. Based on this, the supporting technology of replacing anchor cable with docking bolt is put forward to increase the coordination between supporting member and roadway surrounding rock deformation. The industrial test results of Baode coal mine show that the technology can adapt to the deformation of surrounding rock and effectively prevent the tunnel roof from caving due to the break of anchor cable.

Failure mechanism of surrounding rock with high stress and confined concrete support system

Surrounding rock control is a big challenge in roadway with high stress in deep underground engineering. To address this issue, Zhaolou coal mine – a typical kilometer deep well is taken as engineering background to monitor and analyze the original support scheme. The analysis shows that the following main reasons lead to the support failure in roadway with high stress in deep underground coal mine. Roadway deformation is large and lasts longer with a large extent of damage; all anchor bolts are in severely damaged surrounding rock zone without reliable adhesive basis; and U-shaped steel arch unevenly contacts with surrounding rock without sufficient bearing capacity. With summary of support failure mechanisms on-site, a concept of “high-strength and integrity support” is put forward; a support system with square steel confined concrete (SQCC) is developed; and a full scale in-door comparative test is conducted on its core component – SQCC arch and also on the conventional U29 arch. The research shows the bent and damaged legs of U29 arch result in dramatic reduction of bearing capacity of arch. However, the SQCC arch with similar steel content has a bearing capacity of 2.15 times of that of U29 arch and still has a higher post bearing capacity even after the arch is deformed dramatically. Quantitative evaluation index is established such as vault displacement control rate and bolt strength utilization rate; comparative analysis is made on surrounding rock control mechanism and the mechanical properties of support components under the influence from the four factors – arch strength, geostress, lateral pressure coefficient and surrounding rock mechanical parameters; and good control effect on surrounding rock of SQCC support is verified. Comparative tests are conducted on site. The monitoring results show the roadway surrounding rock deformation on the test section of SQCC support is only 21.2% of that on test section of U29 arch support; and no yield and damage occurs on the test section of SQCC support. Therefore, the SQCC support system is proved to be effective on surrounding rock control.

Application of Distributed Optical Fiber Sensing Technology in Surrounding Rock Deformation Control of TBM-Excavated Coal Mine Roadway

After roadway excavation, the deformation and failure of roadway surrounding rocks typically results in roadway damage or collapse. Conventional monitoring techniques, such as extensometers, stress meters, and convergence stations, are only capable to detect the stress or strain data with the shallow layers of surrounding rocks, and they require arduous manual works. Moreover, in the abovementioned monitoring techniques, the monitoring instruments are installed behind the excavation face; therefore, the strain and deformation occurring in front of excavation face cannot be detected. In order to eliminate these shortcomings, an innovative monitoring system for surrounding rock deformation control has been developed base on Brillouin optical time domain reflectometry. Compared with conventional monitoring systems, the proposed system provides a reliable, accurate, and real-time monitoring measure for roadway surrounding rock deformation control over wide extension. The optical fiber sensors are installed in boreholes which are situated ahead of the excavation face; therefore, the sensors can be protected well and the surrounding rock deformation behaviors can be studied. The proposed system has been applied within a TBM-excavated roadway in Zhangji coal mine, China. The surrounding rock deformation behaviors have been detected accurately, and the monitoring results provided essential references for surrounding rock deformation control works.

Non-destructive testing and pre-warning analysis on the quality of bolt support in deep roadways of mining districts

The bolt support quality of coal roadways is one of the important factors for the efficiency and security of coal production. By means of a self-developed technique and equipment of random non-destructive testing, non-destructive detection and pre-warning analysis on the quality of bolt support in deep roadways of mining districts were performed in a number of mining areas. The measured data were obtained in the detection instances of abnormal in-situ stress and support invalidation etc. The corresponding relation between axial bolt load variation and roadway surrounding rock deformation and stability was summarized in different mining service stages. Pre-warning technology of roadway surrounding rock stability is proposed based on the detection of axial bolt load. Meanwhile, pre-warning indicators of axial bolt load in different mining service stages are offered and some successful pre-warning cases are also illustrated. The research results show that the change rules of axial bolt load in different mining service stages are quite similar in different mining areas. The change of axial bolt load is in accord with the adjustment of surrounding rock stress, which can consequently reflect the deformation and stability state of roadway surrounding rock. Through the detection of axial bolt load in different sections of roadways, the status of real-time bolt support quality can be reflected; meanwhile, the rationality of bolt support design can be evaluated which provides reference for bolting parameters optimization.

Research and application on the horizontal tectonic stress influence on the stability of deep roadway

According to the test result of ground stress of -817.0m Horizontal shaft station in Huainan mine area, the stress field distribution characteristic of mainly with horizontal tectonic stress was analyzed, the deep roadway surrounding rock deformation and failure regularity under the situation of the maximum horizontal stress and roadway axis in the different angle were studied by using the FLAC3D simulation software, and then specific way of supporting and its parameters were designed combined with the shaft station layout conditions. The result shows that: the roadway stability is relatively good when its tunnel axis the maximum horizontal stress direction within 30° angle, surrounding rock deformation and the plastic zone at the top and bottom are significantly increasing along with the angle increased from 30° to 90°, the major form of deep soft rock deformation and failure is the floor heave. According to the simulation results, the conditions under the layout condition of the shaft station roadway, support methods and support parameters have been designed and determined. The supporting method can be referenced by the similar mines.

Experimental Study on Properties of Steel-plastic Geogrids and their Application in Supporting Engineering

Steel-plastic geogrid greatly improves the stability of surrounding rock in the supporting project due to the qualities, such as high strength, high toughness and less creep deformation. Through the geogrid mechanical properties analysis, tensile strength, deformation and creep test and field experiment and so on, we researched and analyzed steel-plastic geogrids’ characteristics and supporting effect, and concluded the influencing factors of steel-plastic geogrids’ characteristics, load-time curve and the steel-plastic geogrids’ variation under different temperature. We explained steel-plastic geogrids’ supporting effect through specific examples of projects. The results of the studies are listed as follows: (1) Steel-plastic geogrid has good resistance to deformation and node failure of roadway surrounding rock deformation, which has good tensile property, creep property and deflection performance; (2) It is feasible to support the surrounding rock by forming a whole combined joint support with steel- plastic geogrid and high-strength prestressed anchor rod.

Catastrophe mechanism and disaster countermeasure for soft rock roadway surrounding rock in Meihe mine

The soft rock’s heterogeneity and nonlinear mechanical behavior cause extremely difficult maintenance on the soft rock roadway. Aiming at the asymmetric deformation and destruction phenomenon appearing after excavating and supporting the 7101 air return way in Meihe mine, this paper comprehensively adopted a variety of methods to analyze the roadway surrounding rock deformation rule, obtaining the roadway surrounding rock stress and plastic zone distribution rule under no supporting condition and the roadway surrounding rock deformation features under original symmetric supporting condition. Furthermore, this paper revealed the catastrophe mechanism, and proposed the concept of “weak structure” and the disaster countermeasure of “overall stabilizing the roadway and strengthening the support of weak structure”. The industrial test shows that the disaster control technology can realize the coordination deformation of the supporting structure and roadway surrounding rock, thus significantly controlling the deformation of roadway surrounding rock.

Support technology for mine roadways in extreme weakly cemented strata and its application

For the engineering geology conditions of bad mine roadway roof and floor lithology in extremely weak cemented strata, the best section shape of the roadway is determined from the study of tunnel surrounding rock displacement, plastic zone and stress distribution in rectangular, circle arch and arch wall sections, respectively. Based on the mining depth and thickness of the coal seam, roadway support technology solutions with different buried depth and thickness of coal seam are proposed. Support schemes are amended and optimized in time through monitoring data of the deformation of roadway, roof separation, I-beam bracket, bolt and anchor cable force to ensure the long-term stability and security of the roadway surrounding rock and support structure. The monitoring results show that mine roadway support schemes for different buried depth and section can be adapted to the characteristics of ground pressure and deformation of the surrounding rock in different depth well, effectively control the roadway surrounding rock deformation and the floor heave and guarantee the safety of construction and basic stability of surrounding rock and support structure.

The Numerical Simulation and Supporting Design of Gob-Side Entry Retaining in Gradient Medium Thick Coal Seam

In order to solve the technical problem of gob-side entry retaining in inclined coal seam, combined with the practical mining conditions in a certain mine, this paper adopts the discrete element method, applies numerical simulation to analyze inclined coal seam gob-side entry retaining with three different supporting ways, and studies surrounding rock deformation characteristics of gob-side entry retaining. The research results show that the filling body upper boundary for right side can control the roadway surrounding rock deformation better compared with the boundary is used as the hypotenuse; Meanwhile, the pressure of surrounding rock of coal seam gob-side entry retaining is mainly from the impact of the immediate roof natural fall of the upper goaf tilt and the weight of caving coal gangue and coal seam of immediate roof above; According to the surrounding rock deformation characteristics of coal seam remain gateway along goaf, it is determined to use combined supporting method of concrete filling in roadway sides and anchor wire rope supporting inside the roadways, providing the design basis of gob-side entry retaining in coal seam for the similar geological conditions.

A Research into Extra-thick compound mudstone roof roadway failure mechanism and security control

Using roof accident cases, this paper analyzes the characteristics of extra-thick compound mudstone roof surrounding rock in the laboratory, and then it studies the failure characteristics and instability mechanism of the roof through numerical simulation, together with field measurement of the digging roadway surrounding rock deformation and bolt support load. The results show that roadway support structure is rational and four solutions are proposed for reinforcing surrounding rock timely, enlarging anchorage range, improving the support stiffness of lower rock stratum, and disposing the bolt and anchor cable along the cracks to improve the intensity at the top right angles of the roadway. This study might provide scientific basis for the similar compound roof roadway support in the future.

An artificial neural network for forecasting the amount of Chinese colliery roadway surrounding rock deformation : Yuxiang Zhang & 6 others, in: Applications of computers and operations research in the minerals industries. Conference, Brisbane, 1995, ed ANON (AusIMM), 1995, pp 123–124

An artificial neural network for forecasting the amount of Chinese colliery roadway surrounding rock deformation : Yuxiang Zhang & 6 others, in: Applications of computers and operations research in the minerals industries. Conference, Brisbane, 1995, ed ANON (AusIMM), 1995, pp 123–124