Excavation Technology Research Articles

Study on Safety Tunneling Technology of Secondary Outburst Elimination by CO2 Gas Fracturing in High-Outburst Coal Seam

The No. 3 coal seam in the Yuxi Coal Mine has a measured maximum gas content of 25.59 m3/t, along with a maximum gas pressure of 2.9 MPa, indicating its high risk to gas and outbursts. To mitigate outburst risks of the coal seam, the 1301 working face has been implemented with gas pre-drainage measures by grid boreholes from underlying roadways. After one year of extraction, it was confirmed that the gas content at all 33 test sites was below 8 m3/t, meeting the outburst prevention standards. However, during subsequent coal tunnel excavation, the gas desorption index K1 value frequently exceeded the standard, resulting in numerous occurrences of abnormal gas emission or small-scale outbursts. To tackle the challenges associated with safe excavation following the first-round regional outburst prevention measures, a research and industrial trial of CO2 gas fracturing (CO2-Frac) technology for secondary outburst prevention and rapid excavation was completed. The results show that the dual-hole and high-pressure (185 MPa) CO2-Frac considerably contributes to outburst prevention. K1 exceedances per hundred meters of tunnel excavations were from an average of 2.54 without CO2-Frac to an average of 0.28 after the new technology was implemented, leading to an eight-fold reduction. Additionally, the monthly excavation footage increased from an average of 81.64 m without CO2-Frac to an average of 162.42 m with CO2-Frac, resulting in a two-fold improvement. The dual-hole and high-pressure CO2-Frac is an advanced technology for safe and efficient excavation for secondary outburst elimination in highly outburst-prone coal seams in the Yuxi Coal Mine, with potential for widespread application in similar coal seam conditions.

Field monitoring and numerical simulation for force characteristics of pipe jacking in deep buried moderately weathered slate

Understanding the force characteristics of pipe jacking in rock formations is crucial for ensuring the stability of the structure and construction safety during construction. Yet, very little is explored about its characteristics in rock formations of pipe jacking. This paper presents a case study of constructing a deeply buried moderately weathered slate sewage pipeline using pipe jacking method in Changsha, China. To this end, we propose a novel method to combine field monitoring and numerical simulation representation in an efficacious way. Field monitoring was conducted to investigate the spatial distribution characteristics of jacking force, axial stress, and hoop stress in moderately weathered slate. Numerical simulation methods were employed to discuss the influences of several factors on pipe stress: the pipe-rock contact area, contact relationships at pipe joint interfaces, the height of the jacking force position, and the depth of pipe burial. The results show that hand shield is influenced by the excavation technology, and the distribution of jacking force exhibits a stepped or oscillating upward pattern in moderately weathered slate. The maximum axial stress occurs at the mid-span position of the arched roof of pipe at 30 MPa. Hoop stresses are dominated by compressive stresses with the maximum at-8 MPa. As the pipe burial depth increases, so does the axial stress on the pipe. Lower positioning of the jacking force heightens this stress effect. A larger pipe-rock contact area correlates with reduced axial stress levels. The weakening of the contact interface between pipe joints minimally affects axial stress, as stress primarily transmits through non-weakened areas. To ensure the reliability of the data, automatic monitoring and measuring instruments calibrated for on-site monitoring are used. The results of this study can provide beneficial guidance for the design and construction of pipe jacking.

Quantitative risk assessment of coal mine gas explosion based on a Bayesian network and computational fluid dynamics

A gas explosion is one of the most serious coal mine accidents. The complexity and dynamics of gas explosion accidents, resulting from both multiple risk factors and time-dependent physical parameters, necessitates the use of risk assessment techniques to analyze the accident. A quantitative risk assessment method is proposed for coal mine gas explosions based on a Bayesian Network (BN) and Computational Fluid Dynamics (CFD). The results show that, in addition to the problems of “low vigilance” and “substandard safety education”, the “irrational design of mine gas extraction” has become another major risk factor at the new stage of development of mine excavation technology. Three typical gas explosion areas are selected to analyze the possible consequences of an accident. Based on the probabilistic risk assessment model, time-dependent physical parameters such as accident conditions, location and time are analyzed. The probability of occurrence of time-dependent risk factors is quantified to calculate the risk values of the consequences of explosion accidents corresponding to different times. The proposed method helps to improve the calculation accuracy of updating the risk probability value over time and provides theoretical support for the risk analysis of coal mine gas explosion accidents.

Comparison of Trenchless and Excavation Technologies in the Restoration of a Sewage Network and Their Carbon Footprints

The restoration of aging sewer networks is a fundamental remediation approach with the aim of renewing or improving existing systems. Remediation methods include repair, renovation, and replacement (renewal). The restoration of a sewer network itself can be performed using either excavation or trenchless technologies. While these technologies offer various advantages, they also present disadvantages. The choice of a restoration technology depends on numerous parameters, including economic factors and local conditions (such as the construction of the existing sewage network, available working space, traffic load, and environmental safety restrictions). In addition to the parameters influencing the choice of restoration technology, recent considerations have been given to constraints related to greenhouse gas emissions and the corresponding carbon footprint. Carbon footprint serves as an indicator of the restoration activity’s dependence on fossil fuels, both during implementation and operation. In the 21st century, concerns regarding carbon footprints have rapidly escalated. The reduction in carbon footprints is a crucial objective from both an economic and an ecological point of view. This article specifically addresses the prospects of monitoring the carbon footprint concerning the partial restoration of a sewer network within the historical core of the city of Brno, located in the Czech Republic. This aspect constitutes the unique and innovative contribution of the paper. The intensity of the energy demand of excavation and trenchless technologies is utilized as a direct measure of the carbon footprint of each technology. The comparative assessment demonstrates that the trenchless technology used achieves a reduction of 59.2% in CO2 emissions compared to the excavation technology. The carbon footprint of Variant 1 (trenchless technology) is 9.91 t CO2 eq., while the carbon footprint of Variant 2 (excavation technology) is 24.29 t CO2 eq. The restoration of open pipelines produces more emissions due to the higher energy consumption, making it more expensive in terms of fuel costs, waste disposal costs, and the corresponding environmental hazards.

Determining the Level of Structural and Mechanical Degradation of Steel in the Supporting Structure of Mining Excavation Machinery

The steels from which the components of mining machinery are constructed must be based primarily on knowledge of their behaviour under environmental conditions and of the excavation technology. Secondly, the structural changes undergone by the materials due to mechanical and thermal processing and the stresses generated by the action of excavation forces that can induce internal stresses at a level that is difficult to determine must be taken into account. Determining the level of structural and mechanical degradation involves sampling the load-bearing structure elements of the excavation and storage machinery for analysis of the mechanical and chemical properties of the component materials. The paper focuses on issues related to the structural and mechanical degradation of steel as a material for parts of mining machinery. In this paper, a methodology for evaluating the degree of structural degradation of three types of bucket wheel excavators with different operating hours (ERc 1400-30/7-07 with 50,400 h, ERc 1400-30/7-08 with 69,264 h, and SRs 1300-26/3.5 with 112,000 h) is proposed. The methodology aims to provide a quantitative assessment of the structural degradation by considering the specific elastic limit of the material used in the machines and the number of hours of operation. This method uses a minimum set of destructive mechanical tests, such as tensile, resilience for three working temperatures, chemical analysis, and durometry on resistance elements taken from the machine, as well as the use of Weibull analysis. By combining this information with the number of hours of operation, a comprehensive evaluation can be made to determine the extent of degradation and potential maintenance requirements. The use of a minimum set of mechanical tests ensures an efficient and cost-effective approach to assessing the structural integrity of these machines. The metallographic analysis highlighted a predominant and defined form of grain rearrangement in the E14-07 machine after only 50,400 h. The constituents identified in the samples taken from the three machines are ferrite and pearlite. The highest hardness of the samples was recorded for the E14-08 machine, with values between 162–165 HV10. For bucket wheel excavators E14-07 and E14-08, the material structure showed elongated grains in the direction of deformation, compared to the material structure of E13-04, which has finely equiaxed grains. As a result of the research, final conclusions were formulated.

Excavation and Construction Technology of Diversion Tunnel under Complex Geological Conditions

During the construction of a diversion tunnel, geological problems often include faults, fragile strata, hard rock formations, karst landforms, etc., which may have adverse effects on the excavation and construction of the diversion tunnel. Based on the analysis of the engineering overview, this study designed a new construction technology for the excavation of water diversion tunnels in hard rock layers and high-karst areas. Based on tunnel seismic prediction (TSP) technology to achieve advanced geological prediction, combined with actual geological conditions, construction difficulties are analyzed. Then, detection technology is used to collect two-way travel time, amplitude, and waveform data. By processing and analyzing the detection image, the spatial orientation and length of the main tunnel during the construction of the diversion tunnel are calculated. After completing the construction ventilation and wind, water, and electricity layout, the excavation construction procedure is designed. In the specific excavation design, the tunnel curtain excavation technology, tunnel body excavation and support technology, excavation grouting technology, important unfavorable geological tunnel section excavation technology, upper/lower flat section excavation technology, upper/lower curved section excavation technology, and vertical shaft section excavation technology were elaborated. Finally, a plan was made for the reuse process of slag material and a construction quality control system was established. During the testing process, it was found that the antidamage coefficient of the side wall was above 0.9 after using the technology described in this article. Therefore, it indicates that the excavation construction technology designed in this article can ensure the support capacity of the side wall of the diversion tunnel, which is suitable for the excavation of the main tunnel during the construction of the diversion tunnel.

Research on the performance of the active vibration cutting system for the rotary cylinder of a tunneling machine

High-efficiency rock breaking technology is an important problem to be solved urgently in deep mining. The existing auxiliary rock breaking technology for coal mine excavation has problems such as polluting coal, high requirements for tool materials, and difficulty in subsequent washing. In this paper, an active excitation cutting system for rotary cylinder of cantilever roadheader based on alternating valve is proposed. According to the classical calculation formula of cutting load of roadheader, considering the stiffness-damping characteristics of cutting part and cutting cylinder, the simulation algorithm of cutting load is compiled based on MATLAB simulation analysis software. The excitation cutting experiments of different cutting depths are carried out on the cutting test bench, and compared with the simulation algorithm of cutting load. Taking the cutting load as the discriminant index, the influence of oil supply pressure and excitation frequency of rotary cylinder on the cutting load is analyzed based on the simulation algorithm of cutting load. The results show that the error between the simulation results and the experimental results of the active excitation state is less than 12%, and the two are in good agreement. Under the condition of 30 HZ, when the excitation amplitude is 8 Mpa, 10 Mpa, 12 Mpa, 14 Mpa, when the rotary cylinder excitation amplitude is 10 Mpa, the minimum is 131.42 KN. Compared with the rotary cylinder excitation amplitude under the condition of 10 Mpa, when the excitation frequency is 30 HZ, 35 HZ, 40 HZ, 45 HZ, when the excitation frequency is 40 HZ, the minimum is 83.08 KN, indicating that changing the excitation amplitude or oil supply pressure of the rotary cylinder is helpful to adjust the cutting performance.

Application of Cross-hole Seismic Tomography to Inferred Cavities Condition.

The construction of the Rajamandala hydroelectric power plant civil works has experienced critical problems that arise in the implementation process, with the occurrence of cracks cavities conditions in the headrace tunnel locations. We applied the cross-hole seismic tomography to detect important heterogeneities and mechanical proprieties of the formations between two boreholes in this case inferred cracks cavities condition. The seismic source is inside the borehole “a sparker” and the receivers “hydrophones” are in an adjacent one, the sparker is lowered into the borehole one step at the time. Seismic waves, propagating in the tunnel wall rock, spread widely, and are reflected and refracted when encountering interfaces between rocks with different acoustic impedances. Reflected waves returning to the receivers are recorded. After the processing of the first arrivals of the P waves we obtain a cross section of the seismic velocities in between the two wellbores. With the cross-hole seismic tomography, the basis could be provided to the tunnel construction and parameter adjustments to guarantee the construction safety. Our result shown that there is a weak zone above the tunnel with low Vp zone (~1.2 km/s) may be related to weak zone (may be fracture, unconsolidated rock, and fluid-filled rock or landslide caving). Checker-board resolution test is also conducted to determine the tomogram areas that are reliable to be interpreted. Our challenges are we have poor resolution due to not enough raypath. The Cross-hole seismic tomography can effectively and safely guide the excavation of the tunnel section working surface in combination with reconstructed images and excavation technology.

Monitoring of the stress-strain state during preparatory workings

Maintaining and increasing the volume of underground coal mining is possible only if there is a highly efficient technology for conducting and maintaining preparatory workings. The purpose of the research was to assess the parameters of stability control of the contours of the mine workings, anchored with anchorage, to create a technology for intensive and safe excavation of mine workings based on the identified patterns of behavior of adjacent rock massifs. The idea of the approach is to use a man-made stress-strain state to develop an effective technology for fixing a contour rock mass. The mechanism of deformation, displacement, and collapse of rocks in a structurally disturbed inhomogeneous mountain range is investigated to assess the state of the rock mass around the mine workings. The technology of fastening contiguous soil rocks has been developed taking into account the state of the mountain massif around the workings and the parameters of the operation of the anchor supports in mines for fixing rods in workings in order to ensure the safety of mining operations in the mines of the Karaganda coal basin have been determined.

The numerical simulation of rapid excavation technologies under the combined form of hydraulic fracturing and drill-and-blast method

With the aim of the drilling and blasting in underground space, there are problems of poor tunnel formation, large crushing and loosening area, difficult support, low driving efficiency, and special geological conditions that are not suitable for drilling and blasting. According to the fracturing and blasting theory and auxiliary hole effect, a combined hydraulic fracturing and drilling blasting tunneling technology was proposed in this research. Establish a rock breaking model, and according to the mechanism of swelling and breaking, the rock breaking efficiency and effect of swelling and breaking, the number of drill holes and the arrangement of drill holes affect the rock breaking performance; the traditional drilling and blasting method used the change of dynamic pressure and vibration velocity to judge the propagation and attenuation process of blasting vibration, as well as the range of damage area. The ANSYS LS-DYNA, a numerical simulation software, was used to determine the position and size of the top facing holes, the optimal spacing of fracturing holes, blasting holes and auxiliary holes. The static load applied to the arc part can effectively reduce the crushing area, the crack area and the elastic area. The lower rectangular part is arranged with the auxiliary holes reasonably to inhibit the propagation of the blasting shock wave, slow down the development of the fracture, guide the extension direction of the crack, and reduce the damage range of the three areas, avoid low efficiency of deep hole blasting, and judge the practicability and operability of this method based on the timeliness of each stage of excavation. The combined pressing and blasting method with the high-efficiency and short-distance, multi-frequency and high-efficiency excavation effectively controlled the shape of the upper area of the roadway, which contributes to reducing the damage area of the surrounding rock, developing a safe working environment, decreasing the maintenance cost of the roadway in the later stage, and providing a innovative way for the development of underground space in the future.

Construction Technology and Safety Risk Control Measures of Deep Foundation Pit Excavation

Deep foundation pit excavation is a basic and key step involved in modern building construction. In order to ensure the construction quality and safety of deep foundation pits, this paper takes a project as an example to analyze deep foundation pit excavation technology, including the nature of this construction project, the main technical measures in the construction of deep foundation pit, and the analysis of the safety risk prevention and control measures. The purpose of this analysis is to provide scientific reference for the construction quality and safety of deep foundation pits.

Determination of torque for milling working equipment of excavator when repairing a pipeline

Introduction. During the overhaul of the pipeline to remove the soil under the pipe, a trench tool is currently used. The new technology of excavation of soil under the pipeline proposed by the authors, which provides for the use of replaceable milling working equipment for a hydraulic excavator, makes it possible to increase the speed of repair work. The purpose of the article is a theoretical study of the process of interaction between the structural elements of milling equipment and the developed soil.Methods and materials. Based on the basic provisions of the theory of interaction of the working bodies of earthmoving machines with the soil, a mathematical model of the work of the milling working equipment of a hydraulic excavator was created. It makes possible to get the dependence of the resistance forces arising on the cutters of the working equipment, on its design parameters and the physical and mechanical properties of the soil.Results. According to the results of the analysis of the obtained dependence of the torque on the cutting angle and the angular speed of rotation of the milling head, it was found that the greatest influence on the torque required to overcome the forces of soil resistance and the drive of the working body is exerted by the angular speed of rotation of the milling head. The minimum value of the torque in the study area 50 N·m is observed at the point where the cutting angle of the soil is 45º, and the angular speed of rotation of the milling head is 4 rad/sec. The maximum torque 215 N·m was recorded at a cutting angle of 65º and a milling head speed of 10 rad/sec.Сonclusions. According to the results of the theoretical study of the process of cutting soil with the help of the milling working equipment of the excavator, the torque of the hydraulic motor necessary to rotate the milling head was established. The results of the theoretical studies carried out are recommended to be used to calculate the design and operating parameters in the design and creation of an experimental sample of milling working equipment.

Control Technology of Roof-Cutting and Pressure Relief for Roadway Excavation with Strong Mining Small Coal Pillar

In order to solve the problem of serious deformation and failure of surrounding rock and difficult maintenance of gob-side entries with strong mining-induced small coal pillars, taking the A110607 return airway of the Shanwenjiaba Coal Mine as the engineering background, the key parameters of roof-cutting and pressure relief control technology for roadway excavation with strong mining-induced small coal pillars were studied by using two-way concentrated blasting roof-cutting and pressure relief technology, combined with theoretical analysis, numerical simulation and a field industrial test. A collaborative control scheme of “roof-cutting pressure relief + anchor cable combined support” is proposed. The test results show that when the height of roof-cutting is 8 m, the angle of roof-cutting is 15°, and when the width of the coal pillar is 3 m, the effect of roof-cutting and pressure relief is the best. Through the field blasting test, it was determined that the blast hole spacing was 800 mm, 321 charge structure was used in the intact roof, and 221 or 211 charge structures were used in the broken roof and geological structure zones. During the driving and strong mining period, the roof and floor movement of the roof-cutting section of the roadway excavation was reduced by about 38% compared with the uncut section, and the deformation of the two sides of the roadway was reduced by about 44% compared with the uncut section. It shows that the collaborative control scheme of “roof-cutting pressure relief + anchor cable combined support” has a good effect on the roadway excavation driving of small coal pillars in strong mining.

Comparison of different methods to characterise the abrasivity potential and mechanical properties of carbonates with respect to its relevance for practical purposes in excavation technologies

The characterisation of the abrasivity potential of carbonates plays an important role for drilling-based excavation technologies, for example in tunneling or geothermal exploration. Although carbonates are known to have a rather low abrasivity, they have been associated with severe excavation performance reductions. We compared different methods to characterise the abrasivity potential of carbonates with respect to its applicability for practical purposes in excavation technologies. In this study, seven carbonate rocks were investigated which differ with respect to their microstructural properties and degrees of dolomitisation. These carbonate rock samples were selected from different lithological units in Germany (Jurassic: Kelheimer limestone, Wachenzell dolomite, Solnhofen limestone, Pappenheim limestone, Treuchtlingen limestone; Devonian: Wülfrath limestone, Brilon limestone). Rock samples were characterised with respect to basic physical properties (density, ultrasound velocity), microstructure (thin section analysis, XRD), mechanical properties (uniaxial compressive strength UCS, splitting tensile strength STS) and commonly applied abrasivity indices (Cerchar abrasivity index test CAI, LCPC test) as well as derived indices (equivalent quartz content eQu). Our results confirm that the tested carbonate rocks show low abrasivity indices in terms of CAI, LCPC and eQu with an increase in abrasivity potential with increasing dolomite content. The microstructural properties play an important role for the abrasiveness of purely calcitic carbonates. Uniaxial compressive strength and splitting tensile strength were high and can additionally be, as has been shown before, particularly sensitive to sample preparation. We conclude that carefully determining the mechanical properties of carbonate rock samples in combination with common approaches to determine the abrasivity potential is key to properly predict tool wear, and required to derive information on performance in carbonate rocks. This study is the outcome of a research-oriented teaching program at Ruhr-University Bochum within the Geoscience curriculum for students with focus on Engineering Geology. Student authors are listed in alphabetical order (Aderhold to Zinke).

Layered Excavation of the Third Potash Seam with Reduced Thickness of Interlayer Ceiling

The third potash seam of the Starobinsky deposit is mainly mined using the layered mining technology. The essence of the technology lies in the advance excavation of the 4th sylvinite layer by the uppere lava and the joint excavation of layers 2, 2–3 and 3 by the lagging lower lava under the protection of the interlayer pack of rock salt 3–4 (ceiling) left in the goaf. The thickness of the ceiling in accordance with the requirements of the regulatory document should be at least 0.8 m. At the same time, in the mine field of the mine of the Third Mine Administration, there are areas with a ceiling thickness reduced to 0.66–0.70 m. The purpose of the author’s research was to determine the possibility of safe mining of the Third potash seam using the layered mining technology with a reduced thickness of the ceiling. In the course of a full-scale experiment, the geological structure and strength properties of the rocks of the ceiling, its stability in the bottomhole space and the intensity of loading of the bottomhole lining of the lower lavas have been studied in the paper. The research methods also included the analysis of literary sources and statistical processing of the obtained data. It has been established that a decrease in the thickness of the ceiling by 0.10–0.14 m from the required one does not have a significant effect on its strength, while it remains stable in the near-bottom space of the lower longwalls. The main indicators of the manifestation of rock pressure in the studied lower longwalls – the rate of increase of the bottomhole lining in the stope cycles and the lowering of the roof in the bottomhole space – did not exceed the similar indicators in the longwalls with the required thickness of the ceiling. The obtained data indicate the possibility of safemining of the Third potash seam using the layered excavation technology with the thickness of the interlayer rock salt pack 3–4 not less than 0.66 m. In this case, the bearing capacity of the bottomhole lining should be at least 550 kN/m2.

The Analysis of English Sentence Components Based on Decision Tree Classification Algorithm

Decision tree is an important classification method in data excavation technology. It is a predictive analysis model expressed in the form of a tree structure (including binary trees and poly trees). The decision tree method is a more general classification function approximation method. It is an algorithm commonly used in predictive models to find some potentially valuable information by purposefully classifying a large amount of data. In this article, the author tries to analyze the English sentence components based on the decision tree classification algorithm. The author starts with the decision tree, extracts the decision tree rules, and generates a classifier by effectively sorting the decision tree rules, and applies it to classification prediction.

Produbljivanje morskog dna za potrebe izgradnje LNG terminala na otoku Krku

Near Omišalj on the island of Krk, where the construction of a pier for liquefied gas is planned, hydrographic measurements revealed three shoals at depths of 13.5 and 13.6 metres. For the safety of navigation, the seabed had to be deeper than 15.4 m. The geological fabric of the seabed was determined using a hydroacoustic survey and remote operating vehicle. Shallows are formed in a solid carbonate rock mass. Special technology of excavation without blasting was applied. 11,000 m3 of rock mass was excavated which was deposited nearby. The seabed habitat with an area of about 12,500 m2 was changed.

Pose Detection and Automatic Deviation Correction Control Strategy of Crawler Walking Equipment in Coal Mines

Autonomous navigation technology is the basis of underground crawler walking equipment automation. Based on research of the sector laser pose parameter detection method, a pose detection system based on a cross laser is proposed. The mathematical model between pose parameters, laser receiver measurement data and tilt sensor measurement data is established by vector algorithm and the expression of key pose parameters is deduced. This paper studies the deviation correction control strategy of crawler walking equipment and puts forward the point deviation correction control strategy based on roadway excavation technology. Firstly, the end position of the path is determined according to the initial pose of the roadheader. Then, Bessel curve is used to plan the path between the starting point and the endpoint, and the pure tracking algorithm is used to track the planned path. The measurement errors of X and Y coordinates and yaw angle of roadheader within 10 80 m shall not exceed 10 mm, 32 mm and 0.65°. Using the point deviation correction strategy, the positioning error of the roadheader at the end of the path is less than 13 mm, and the yaw angle error is less than 0.16°. In the deviation correction process, the maximum angular velocity of the roadheader is 0.07 rad/s, which is less than 0.82 rad/s of the conventional deviation correction strategy. The results show that the point deviation correction strategy can not only ensure the accuracy of motion control, but also improve the stability of equipment motion.

Development of resource-saving technology for excavation of flat-lying coal seams with tight roof rocks (on the example of the Quang Ninh coal basin mines)

It is shown that the creation of the variants of resource-saving systems for the development of long-column mining is one of the main directions for improving the technological schemes for mining operations in the mines of the Kuang Nin coal basin. They provide a reduction in coal losses in the inter-column pillars and the cost of maintaining preliminary workings fixed with anchorage. The implementation of these directions is difficult (and in some cases practically impossible) when tight rocks are lying over the coal seam, prone to significant hovering in the developed space. In the Quang Ninh basin, 9-10 % of the workings are anchored, the operational losses of coal reach 30 % or more; up to 50 % of the workings are re-anchored annually. It is concluded that the real conditions for reducing coal losses and the effective use of anchor support as the main support of reusable preliminary workings are created when implementing the idea put forward at the St. Petersburg Mining University: leaving the coal pillar of increased width between the reused mine working and the developed space and its subsequent development on the same line with the stoping face simultaneously with the reclamation of the reused mine working.

Application and Analysis of Bolt Support in Mine Driving Roadway

Mineral resources are one of the main energy sources used in industrial production. While the economy is going up, the mining of coal mines and other mineral resources has also intensified. With the deepening of coal mining, the difficulty of mining has also increased. In order to ensure the safe production of relevant enterprises, it is necessary to vigorously apply the supporting technology of mineral resources excavation to reduce the occurrence of accidents in the mining area. Based on this, this paper, on the basis of collecting the geological conditions of a mine, combined with the stability theory of roadway surrounding rock, the existing bolt (anchor cable) support theory, and the factors affecting the reliability of bolt support, analyzed the bolt (anchor cable) support principle and deduced and calculated the support capacity of a single bolt and a group of bolts in the process of mining excavation through the energy conservation theorem. Through Mohr-Coulomb strength theory and limit line analysis theory, a reasonable mechanical model is established, and it is concluded that the ultimate bearing capacity of the bolt will increase with the increase of the length of the anchorage section no matter what support method is used for roadway surrounding rock support, and the anchorage length and ultimate bearing capacity have a nonlinear positive correlation. However, the ultimate supporting capacity of the suspension bolt cannot meet the actual work demand, while the composite beam and composite arch bolt support meet the conclusion. In addition, according to the conclusion and the suggestion that the design of bolt support mode should start with the study of the mechanism of bolt support on the roadway, the application of bolt support mode in the resource mine heading roadway is comprehensively analyzed.