New development of bolting technology for coal roadway

1 Bolt support technology for coal roadway in Yanzhou mining area

Yanzhou Mining (Group) Co., Ltd. actively introduces the most advanced coal roadway bolt support technology in foreign countries, and combines the actual digestion and innovation of Yanzhou mining area to gradually form a complete technical system, namely, design systemization, machine tool matching, monitoring intelligence. Standardization, construction standardization, material standardization and serialization are developing in the direction of “safe, fast and efficient”.

Since 2000, they have developed high-strength support materials for diameter and promoted the application of high-strength full-anchor support systems. The bolt yield strength is greater than 540 MPa, the breaking strength is greater than 700 MPa, and the elongation is greater than 15%. The shape structure is favorable for stirring the resin and improving the anchoring force. In view of the shortcomings of Φ15.24 anchor cable low elongation, small diameter and non-compliance with the "three-path" matching relationship, they developed a Φ18 high-strength large-diameter resin anchor cable with a breaking force greater than 380kN and an elongation greater than 7%. For the locations with large deformation and complicated surrounding rock in complex and difficult conditions, high-strength grouting anchor cables are used, and the breaking force reaches above 500kN. At the same time, the strength of the anchoring agent, steel strip and anchor attachment is increased to match the strength of the anchor.

In order to accurately and timely monitor the information of coal road bolt support and realize intelligent monitoring, they also developed a roof separation monitoring system. The system has a variety of digital display functions, each time a 2mm change, can simultaneously monitor the top plate separation of the 60 displacement sensors, and has a threshold alarm, half-duplex call function, monitoring data can be transmitted to the phone line Ground microcomputer, output various curves and charts. In addition, the simple ACLY-I, II, III three different sizes of roadway surrounding rock deformation instrument and force measuring anchor are also developed. The reflective film shows intuitive reading and high measurement accuracy. They cooperated with relevant manufacturers to develop the development of high-thrust, high-torque anchor/anchor dual-purpose drilling rigs (thrust >10kN, torque >200N.m) and large-stroke, high-torque leg-type bolt rigs , which greatly improved The speed of the eye and the preload of the anchor/anchor. The joint unit for integrated anchoring and anchoring is being developed.

2 Application of neural network in bolting design of coal roadway

Henan University of Science and Technology used MATLAB's BP neural network toolbox to establish a highly nonlinear BP neural network model between the main influencing factors of surrounding rock and the supporting form and supporting parameters. Based on the analysis of the results of the example, the reliability, feasibility and high efficiency of BP neural network based on MATLAB applied to mine underground bolt support design are verified.

They selected several successful examples of mine roadway bolt support as learning samples, and used the factors affecting bolt support as input variables, support forms and support parameters as output variables into the neural network model, and the specific learning algorithm was used to sample the samples. Learning, through the network internal adaptive algorithm to constantly modify the network connection weights and threshold distribution to reduce the trial error to meet the requirements. The network memorizes the learned samples and adjusts the highly nonlinear relationship between the input variables and the output variables through the adjustment of the connection weights and thresholds, and then substitutes the input variables of the roadway into the network, through the network neural inference calculation, and the problem The closest learning sample output pattern is recalled to obtain the bolt support requirements for the roadway. In this study, a neural network was used to establish a design model of mine bolt support form and support parameters, so that the support form, support parameters and other geological conditions and mining technical conditions formed a highly nonlinear mapping, to a large extent. Overcome the shortcomings of previous bolt design methods.

They used the BP neural network design model established by this project to anchor the underground tunnel of Ji'an Mining Group Corporation, Zhangzhou Mining (Group) Co., Ltd., Pingdingshan Coal Industry (Group) Co., Ltd. and Shuangyashan Mining Group Co., Ltd. Jixian Coal Mine. The pole support design verifies the feasibility and efficiency of the two models by comparing the network operation results with the actual state, which lays the foundation for the next study of other support schemes. Practice shows that the artificial neural network has good adaptability, self-organization and strong learning, association, fault tolerance and anti-interference ability. It can be more comprehensively considered to affect the anchor support parameters when it is introduced into the mine roadway support design. Many factors of design can make data association filling in the case of incomplete input data, and realize fast and accurate decision-making of roadway support.

3 Simulation test of bolt support for fully mechanized coal caving face

According to the “Support Theory of Roadway Surrounding Rock Loose Rings”, China University of Mining and Technology, based on the surrounding rock conditions of the full coal caving face of the 3 coal seams in the Nantun coal mine of Yanzhou Mining Area, different dynamic pressure coefficient, lateral pressure coefficient and anchor Under the condition of supporting parameters, the surrounding rock stress distribution, surrounding rock deformation and roadway failure law of bolt support roadway are simulated, which is of guiding significance for the design and application of bolting net support in full coal roadway.

The test uses a true triaxial plane strain test rig, which is loaded up and down, left and right, and front and back. The surface displacement of the roadway and the internal stress value of the surrounding rock are simulated. The displacement sensor and the micro pressure sensor are synchronously collected with the loading process. The displacement of the roadway surface is measured by a resistive displacement meter. The final displacement of the deep rock is measured by measurement. The deformation of the surface line of the model surface is obtained.

The conclusions of this study are as follows:1 There is a pressure relief zone in the roof of the rectangular roadway. The formation of the pressure relief zone is the inevitable result of the stress transfer and concentration after the roadway is opened and the roof of the roadway is destroyed by the external force. The size and side pressure Close relationship, side pressure and large pressure relief zone are small, and vice versa. The deformation of the surface of the roadway is that the two gangs are larger than the top and bottom, and the two gangs inside the roadway are seriously damaged. The corner of the roadway is stressed and weak, indicating that the gang and the corner are the key points of the rectangular roadway support, especially the setting of the top slanting anchor. Preventing cutting is essential. 3 The rectangular anchor net support roadway under the action of asymmetric pressure is approximately elliptical, and the long axis is perpendicular to the direction of the maximum principal stress. 4 Loose circle theory is an effective method for the design of fully mechanized coal roadway support. According to the theory, the support parameters can maintain the stability of the roadway well when the dynamic pressure parameter reaches 6 or above, and it is simple and easy. Under the condition that the thickness of the combined arch is similar, the "short-tight anchor" can better control the deformation of the surrounding rock than the "long-sludge anchor", but considering the technical progress and the speed of construction, the spacing between the anchors A 2.0m x 0.8m is a good choice. ⑤ large surrounding rock of greater than 1.5m, the metal nets to maintain stability and improve the quality of the roadway is essential, where possible, the conditions should be selected stiffness and greater strength cold drawn steel mesh.

4 Application of loose circle theory for bolting of all coal roadway

Based on the study of the stability of the whole coal roadway and the design principle of the bolt support of the whole coal roadway, the Shandong Coal Science Research Institute carried out the whole coal application to the application of the loose circle theory in the Nanxun Coal Mine and the Jining No. 2 Coal Mine of Yanzhou Mining (Group) Company. Road bolt support has achieved good technical and economic benefits.

The three-layer coal mining in Nanxun Coal Mine and Jining No. 2 Coal Mine adopts the top coal caving method. The working face roadway belongs to the whole coal roadway. The original design is the miner steel frame shed support, and through the observation and study of the surrounding rock loose circle of the roadway, A bolt support test was carried out. The BA-II type surrounding rock loose circle tester and Rayleigh wave detector were used to test the surrounding rock loose circle of the roadway. The test results show that the surrounding rock loose ring of the 13th working face under the working face of Nantun Coal Mine belongs to the middle loose moving circle, and the anchor support parameters can be designed according to the suspension theory; the 2301 working face transportation roadway of Jining No. 2 Coal Mine belongs to the large loosening In the circle, the bolt support parameters are designed according to the combined arch theory. In order to detect the quality of the bolt support and the effect of controlling the surrounding rock, they also carried out the mine pressure observation. The observations were mainly the convergence deformation of the roadway, the stress of the bolt, and the drawing test. The research shows that the traditional I-steel shed support is passive support, while the full-coal roadway bolt support is the active support, and the bolt support has better effect than the I-steel shed support to control the surrounding rock. When Jining No. 2 Coal Mine adopts I-beam steel frame shed support, the cumulative displacement of the top and bottom plates is 60-100mm, the cumulative displacement of the two gangs is 70-150mm, and the bolt support is reduced to 11mm and 12.5mm respectively. The influence of the leading bearing pressure is also reduced from 48m to 15m.

The study concluded that: 1 The thickness and strength of the top coal in the whole coal roadway are the key factors affecting the stability of the roadway. 2 The suspension effect and combined arch effect of bolt support are simultaneously and mutually influential, and the suspension effect is in the main position of the medium and small loose moving roadway; for the large loose circle, there is no stable rock layer in the roof of the roadway, and the combined arch function In the main position. 3 The whole coal roadway is affected by the dynamic pressure of the mining face, but the dynamic pressure action range is not large and the time is not long. The support design should determine the support form and support of the roadway according to the size of the roadway loose ring when the roadway is subjected to static pressure. parameter.

5 Using loosening ring to carry out bolting support reform of mining roadway

The Shandong Institute of Coal Science conducted a test on the surrounding rock loosening circle of Xinzhuang Coal Mine in Laiwu City. Based on the test results, a new bolt support scheme was proposed. The test was carried out in the 3197 working surface track and succeeded.

The mining roadway of the working face of Xinzhuang Coal Mine is driven along the bottom floor of the coal seam. It is supported by fast hard cement anchor. The rod body is round steel of Φ14mm×1400mm, and the anchor of one roll of fast hard cement is anchored. The bolt is arranged perpendicular to the surface of the roadway. The spacing between the anchors is 800mm×800mm. Each anchor is provided with 3 anchors, 3 upper anchors and 2 lower anchors. The wooden pad and iron tray are used. Since the dip angle of the coal seam is relatively large and the metal mesh is not used, the coal body between the upper bolts is easily loosened by the mining effect, so that the tray is suspended and the bolt loses the support effect; There is a lack of connection between the poles, and the overallity is poor, which is not conducive to the maximum self-supporting ability of the roadway roof.

This research was carried out by using the BA-II type surrounding rock loose circle tester in the 3195 working surface track and the 1918 transport auxiliary roadway. Each roadway was observed in 4 measuring areas, and each test was divided into the upper 2 One hole is drilled and one hole is drilled. The results of field observations show that the maximum and minimum values ​​of the loose circle are 1150mm, 1200mm, 950mm, and 900mm, respectively. The test was carried out under the influence of the roadway without being subjected to dynamic pressure. Therefore, it is reasonable to carry out the support design according to the loose ring of 1200mm if the long-term rheological characteristics of the working face are not considered in the support design. The roadway is supported by bolts. The rod body is Φ14mm×1700mm metal round steel. Each hole uses 1 roll of fast hard cement roll. The spacing between the bolts is 800mm×700mm. Considering that the coal body of the upper gang is affected by the mining, it is easy to fall off. In the upper part of each row of the roadway, a steel ladder with a size of 100mm×2000mm is installed, and the steel is separated by steel bars every 200mm. The long axis of the wooden pallet is arranged along the course of the roadway. After adopting the new support scheme, the integrity and stability of the roof and the two gangs of the roadway are better. The average roof is 155mm, the average relative displacement of the two gangs is 170mm, and the average shrinkage of the roadway section is only 7%. It not only ensures the safety of the roadway anchoring, but also reduces the resistance of the roadway ventilation.

6 Roadway anchor support for island fully mechanized caving face based on ground stress test

Zhangzhou Mining (Group) Co., Ltd. Jining No. 2 Coal Mine is based on the complex geological conditions of the 23rd 03 island fully mechanized caving face. Based on the ground stress measurement analysis, the information feedback design method is used to carry out the bolt support of the roadway of the fully mechanized caving face. Protection design.

The conditions of the roadway in the fully mechanized caving face of the 23rd 03 island of Jining No. 2 Coal Mine have the following characteristics: deep mining and large ground pressure; both sides of the island working face are all along the small coal pillars along the goaf; the geological structure is complex, lithology The thickness of the coal seam varies greatly; the bottom plate is soft and expandable; the production surface is high in output, the equipment is bulky, and the roadway section and support conditions are required to be high.

They adopted the method of systematic measurement and observation based on the ground stress field, roadway mine pressure and bolt load conditions, and the systemic bolting design method based on computer numerical simulation, using high-strength full-length anchor bolt + tight After the installation of the anchor cable + steel strip support method, the track chasing groove has not undergone any maintenance during the recovery, and the transport chute can meet the production requirements only after a simple undercover repair. The systematic observation of the roadway supported by the initial design scheme shows that the roadway support effect is improved compared with the adjacent Φ20mm×2200mm20MnSi anchor short anchors in the adjacent 23 underground 02 fully mechanized caving face. It has created conditions for the rapid advancement of the mining face.

The practice of this mine shows that due to the release of stress generated by adjacent goafs, the horizontal stress in the roof of the empty roadway is low, so it is easy to sink, that is, the deformation of the roof is inevitably larger than the solid coal under the same stratum conditions. Lanes; the roadway bolts are extended or fully anchored so that the force of the bolts is distributed over a wide range, and the tensile stress concentration does not occur like the end anchors, thus avoiding the formation of continuous tensile fractures. Therefore, the full-length anchor bolt should be adopted for the 23-hole 03 island working face of the mine; the deformation of the small coal pillar along the empty side is larger than the solid coal side, the average shrinkage of the roadway section is 25%, and the test roadway has withstood the working face back mining. The test of pressure influence meets the requirements of production.

7 Improve the quality of coal roadway support by perfecting full thread bolt support technology

With the gradual increase of the tunneling along the heading of the Dongtan Coal Mine of Zhangzhou Mining (Group) Co., Ltd. and the mining of the top coal in the top coal, the coal body of the gang is broken and formed poorly, and the phenomenon of the coal body moving closer to the lane is obvious. In the case of bolt support, there is a general situation that the coal piece falls and the bolt fails. Not only the roadway repair and reinforcement work is large, but also there are safety hazards. By applying and perfecting the full-threaded bolt support technology, they solved the problems of failure of bolt support, high cost of support and low level of single entry.

The full-threaded anchor is a new type of bolt, which is made of a non-longitudinal spiral steel bar which is very close to the shape of the finished rolled steel bar. The two transverse ribs on the steel bar are spirally distributed and can be screwed into the nut. Compared with other types of bolts, the rod has the following characteristics: the rod body does not need to be machined to tighten the thread, ensuring that the length of the rod body is strong, and there is no weak cross section, which overcomes the stress concentration and breakage of the conventional bolt when the side pressure is applied to the side of the bolt. Disadvantages; the rod body adopts hot-rolled full-length continuous thread, the production process is simple and the cost is low; when the loose broken rock layer is supported, the second fastening can be carried out at any time, and the common bolt is not affected by the broken length of the rod head. The trays that appear to be restricted are not attached to the coal wall; it is very convenient to intercept the rods of different lengths according to the needs of the site, and can meet the requirements of end anchors, extended anchors and full-length anchoring forms.

In use, it also perfected its own problems: the lock nut was changed from ordinary casting to precision casting, which improved the quality of the nut, effectively solved the problem of large gap between the nut and the rod body, and increased the length of the nut from 35mm to 55mm. The effective tightening length of the large anchor rod and the nut eliminates the failure of the bolt support caused by the wire retreat; the bolt pre-tightening tool is changed from the 30-type pneumatic trigger to the 50-type high-power trigger, and is timely after the bolt is injected. Fastening, the bolt pre-tightening force is increased from 100N·m to 200N·m, ensuring the effective bearing capacity of the bolt support; improving the construction process, scientifically analyzing the “three-path” clearance to achieve the best matching state, multiple scenes The anchoring force detection is above 15t, which improves the construction quality of the bolt; makes full use of the on-site working hours, improves the timeliness of the support of the gang, and timely supports the broken area before the pressure of the gang is released, and puts the coal wall piece in one place. The opportunity to fall.

8 Deep coal roadway roadway bolting support

The coal mining research institute Beijing Mining Research Institute and Zhangzhou Mining (Group) Company Dongtan Coal Mine jointly developed the “Dongtan Mine Deep Coal Roadway Bolt Supporting along the Roadway” to solve the deep high stress coal in this coal mine. The support problem of the lane has reached the international advanced level.

This project is one of the key research projects of Yanzhou Mining (Group) Co., Ltd., with a total investment of 5.02 million yuan, which lasted nearly two years. In the research process of this subject, they mainly used the principle of anchoring the balance arch, using numerical analysis to determine the size of the coal pillar and the initial support design, and absorbed the research results of the existing coal roadway bolt support. Combined with the characteristics of mine pressure display in the deep well high ground stress fully mechanized top coal caving face, the bolt support is adopted in the goblin roadway with large depth and strong impact tendency.

The underground experiment and engineering monitoring in Dongtan Coal Mine show that the deformation and coal pillar size of the roadway proposed by the research project have important guiding significance, which can effectively avoid the roof falling phenomenon during excavation and improve the integrity of the coal pillar. It eliminates the phenomenon of gangs and gangs, and creates safety conditions for reducing air leakage in the roadway and preventing fire in the goaf. At the same time, the application of bolt support in the empty roadway also greatly reduces the cost of support, reduces the labor intensity of workers, and improves the yield of the mining face. In addition, the use of small diameter resin anchor cable also strengthens the control of the coal seam, effectively ensuring the safe use of the roadway, shortening the distance of the advance support, and greatly reducing the damage degree of the roadway.

Experts pointed out that the research results can increase the output value of Dongtan Coal Mine by 41.22 million yuan, increase profits and taxes by 13.31 million yuan, and demonstrate the promotion and application of bolt support in the coal mine roadway in Yanzhou mining area and the whole country. effect.

9 Roadway anchor support for island fully mechanized caving face based on ground stress test

Zhangzhou Mining (Group) Co., Ltd. Jining No. 2 Coal Mine is based on the complex geological conditions of the 23rd 03 island fully mechanized caving face. Based on the ground stress measurement analysis, the information feedback design method is used to design the roadway bolt support. Field observations show that the roadway support effect is good, ensuring safe and efficient mining of the working face.

The 23rd 03 island fully mechanized caving face is located in the middle of the second mining area, with a length of 1350m from east to west and 185m from north to south. The coal seam is stable and has a simple structure. The eastern part of the coal seam roof is grayish-white sandstone with hard lithology; there is a layer of 0.5m thick mudstone pseudotop and 5.5m thick siltstone direct roof in the west. The working face has an average burial depth of 547.4m and belongs to deep mining. By establishing a computer numerical calculation model, they used FLAC software to simulate several feasible support schemes to determine the optimal support scheme.

The track is slotted in the 23nd 02 transport slot, communicated through the 2# contact lane, the second mining track uphill and the north wing track alley, and arranged in the 3 lower coal seams. The section of the groove is 4.3m×3.2m, and the anchor net beam and anchor cable are used for joint support. Roof bolt Φ22×2400mm, anchor bolt Φ22×1800mm, all are full-length anchor resin anchors, spacing between 800mm×800mm; anchor cable Φ15.24×800mm, 2 rows per row, row spacing 2400mm; top net For the 8# wire warp and weft net, the net is 123 wire diamond mesh. The roadway is sprayed with C20 concrete along the air side. The transportation slot is opened in the north wing tape lane and is arranged in the 3 lower coal seams. It communicates with the second mining pipe through the 23 lower 04 transport chute. The section size, mode, bolt specifications and support arrangement of the groove are the same as the track groove.

Practice shows that the anchoring bolts of the roadway are extended or fully anchored, so that the force of the bolts is distributed over a large range, and the tensile stress concentration does not occur like the end anchors, thus avoiding the formation of continuous pulling. The rupture zone is extended; the deformation of the small coal pillar along the air side is larger than the solid coal side, and the average shrinkage rate of the roadway section is 5%. The test roadway has withstood the test of the dynamic pressure of the working face.

10 Coal roadway anchor top control technology under difficult conditions

Yanzhou Mining (Group) Co., Ltd. Nanxun Coal Mine has developed a complete set of bolting support and roof control technology for coal seam roadway under difficult conditions, including design and testing, determining the warning line for roof dynamic detection, and timely modifying the support design with inspection data. And the implementation of appropriate remedial measures, engineering practice shows that the stability of the IV and V coal seam roadway under the bolt support is better than the shelf support.

In the mining roadway of Nantun Coal Mine, the strength of coal and rock mass in some roadways is relatively low, the stability of surrounding rock in mining roadway is relatively poor, and the narrow coal pillar retaining roadway has many roadways along the goaf. Stress test shows the maximum horizontal principal stress of the mine field and The ratio of self-heavy stress is 1.8, and there is a relatively large horizontal tectonic stress in coal-bearing strata. They followed the initial design—on-site inspection—the technical approach to modifying the design to carry out research on this topic, especially the application of the top surface displacement value modification design and the application of the roof separation observation value to improve the roof support. The amount of roof subsidence is one of the important basis for measuring the stability of the roof of the bolt support roadway. The research shows that when the subsidence of the roof reaches or exceeds the allowable amount of subsidence of the roof within 10d or 50d of the roadway, and the subsidence of the roof before the mining period is expected to reach 70% of the final allowable sinking, regression analysis is used. When calculating the amount of roof subsidence during the service period of the roadway to reach 90% of the final allowable sinking amount, consideration should be given to modifying the initial design of the bolt or taking remedial measures.

Since the design width of the fully mechanized mining roadway is a certain value, three types of anchor rods and two types of W steel strips are used. When the displacement value of the roof of the bolt support roadway exceeds the specified index, the design of the anchor should be changed first, and then the specification (length, rod diameter) of the anchor used should be considered. The application of the roof separation observation can be divided into two cases: one is that if the roof separation value in the anchor layer exceeds the allowable sinking amount of the final roof, it indicates that the density of the anchor is not enough, and the spacing between the anchors should be reduced. Or increase the anchoring force; the other is that the separation layer outside the anchorage range exceeds the critical value, indicating that the length of the anchor is not enough, the length should be increased, the anchor cable should be increased or the support should be supported.

11 Application of spiral anchor in support along empty coal roadway

The Baodian Coal Mine of Zhangzhou Mining (Group) Co., Ltd. through the theoretical analysis of the mining pressure deformation law of the overlying strata structure along the goaf and the spiral bolt support technology, and through the actual observation and comparison on the site, found out the comprehensive coal caving work. The new support measures of spiral anchors along the empty side of the roadway have achieved good technical and economic effects.

The requirement of the spiral anchor to retain the thickness of the coal pillar along the air side is generally 3.0-3.5 m. To this end, they determined a reasonable aperture difference based on the actual conditions of the surrounding rock of the mine before use. Under normal circumstances, the diameter difference in the coal body is 10 to 15 mm, and the anchoring force can reach 100 kN or more without the displacement of the anchor. If the anchor is displaced, the anchoring force will continue to increase as the displacement increases until the bolt body is pulled off. However, the diameter difference cannot be too large, otherwise the bolt is difficult to install. If the diameter difference is too small, the anchor will not generate anchoring force to the surrounding rock.

The installation process of the spiral anchor is as follows: anchor hole → hanging ladder → installation anchor. The installation tool can use a pneumatic wrench, and its impact swing torque must not be less than 1400N?m. Installation method: drill the hole smaller than the outer diameter of the bolt in the reinforced rock mass, place the anchor end of the anchor at the drill hole, connect the anchor to the installation machine through the rotary joint, start the installation tool, anchor The rod is screwed into the rock mass. In order to facilitate the testing work of the anchoring force in the underground, it is required to process 3 to 5 anchor rods which can be used for anchoring force test at the end of the rotating joint of the shaft when the 500 sets of bolts are produced. The use of the MLX series of screw anchors saves $9.8/root compared to the use of resin anchors. The biggest feature of the spiral anchor is that it can be recycled. If calculated according to the recoverable rate of 30%, the cost per 10,000 tons of coal can be 52.88 million yuan. Experts pointed out that this achievement shows that the use of spiral anchor reinforcement technology in the coal roadway along the empty coal can effectively solve the problem of poor anchorage of the end and control the displacement deformation of a gang along the air side. A more reasonable form of support for severe deformation of the roadway.

12 New coal bolt system developed successfully

Based on the research and test of the mechanism of the anchor system, the Xinglongzhuang Coal Mine of Zhangzhou Mining (Group) Co., Ltd. has developed a new type of bolt system, which has fully proved its advanced nature through practical application in extra-thick coal seams. Broad prospects for promotion.

This achievement includes the following aspects:

1 The surface structure of the anchor is optimized. Most of the resin anchor rods used in China are two-way two-stranded rebar or non-longitudinal right-handed rebar. The former has a longitudinal radius of rotation greater than that of the rebar, and the latter easily brings the resin colloid to the anchor when the rod rotates. The shallow part of the hole is not conducive to the filling of the anchoring agent. In response to the above defects, they specially rolled a one-way longitudinal steel with no longitudinal reinforcement to make a bolt body. The left-handed thread is opposite to the direction of rotation when the anchor is injected. When the resin roll is stirred, the thread exerts a strong pressure on the roll. The corrugated anchor agent can fill the crack in the hole and remove the sewage in the hole, thereby increasing the anchoring agent and The grip between the rods and the bond between the anchor and the rock mass.

2 new strong anchor processing technology. The commonly used anchor rod body diameter is generally larger than the thread segment. The local heat treatment technology is used to improve the strength of the thread segment or the strong technology such as variable cross section, which has the disadvantages of increased material brittleness and lower elongation. To this end, they pioneered hydraulic non-heat treatment technology, which caused the damage of the bolt to be transferred from the threaded section to the rod section, and the breaking strength was increased by about 24%.

3 strip steel cross-section shape and spherical nut coordination optimization. By casting a billet with ductile material and rolling out a profiled steel strip, the I-beam and W-shaped steel strips have the same structural performance, and the weight is reduced by 85% and 40%. The anchor plate made of the steel strip basically maintains the original strength of the I-beam, and the tray is omitted, the cost is reduced, and the process is simplified. In addition, they also change the nut into a spherical shape, which cooperates with the crown hole on the steel strip. When the anchor is tilted or the anchoring coal body is displaced, the displacement between the nut and the steel strip anchor plate can be adjusted. Eliminate stress concentration.

4 speeding easy to install high-strength resin anchoring agent. High-strength solidification can be achieved within 30 seconds, with high drawing force.

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