Mining Support Research Articles

Temperature effects on stress–strain behavior of underground openings in permafrost zone

The authors describe the research results on the temperature effects on the stress–strain behavior of rock mass around single openings driven in permafrost beyond the influence zone of stoping. The variation patterns of stresses and displacements in rock mass and at the boundary of an underground opening are found depending on its operating life and ventilation air temperature. In terms of the Aikhal mine of ALROSA, it is shown that in an opening at a depth of 350 m, given its ventilation temperature is 20 deg for 3 years, the vertical convergence is comparable with elastic displacements caused by the opening driving. An approach is proposed to determining rock stability category based on expected displacements of an opening during its ventilation. The research results are meant for guidelines and regulatory documents on justification of mine support designs in permafrost zone.

A buoyancy vertical transport system of deep-sea mining

Generally speaking, the systems of deep-sea mining consist of a mining support vessel at surface, a seafloor collector on seabed, and a vertical transport system connecting them. The traditional vertical transport systems of deep-sea mining, which are either hydraulic or airlift, have low efficiency and high cost. In this paper, a kind of buoyancy vertical transport system of deep-sea mining is briefly described. Unlike the traditional ones, this new transport system is based on buoyancy and gravity, which could work in arbitrary depth of water but cheaper.

Experimental study on the evolutional trend of pore structures and fractal dimension of low-rank coal rich clay subjected to a coupled thermo-hydro-mechanical-chemical environment

In order to study the thermo-hydro-mechanical-chemical (THMC) behaviors of low-rank coal rich clay (LRCRC), a triaxial testing machine with THMC effects of high pressure and high temperature was built. Then, mercury injection tests, fractal dimension analysis and infrared spectroscopy analysis were carried out on LRCRC specimens subjected to a coupled THMC environment. The results showed that: 1) as the temperature increased, the sub-micro pores gradually transformed into other types of pores. Moreover, the formation rate of new pores during pyrolysis was slower than the expansion rate of existing pores; 2) the overall meso-physical parameters and fractal dimension of specimen decreased first and then increased with the increase in temperature; 3) at a given temperature, for sub-micropores (0–10 nm), the reduction rate of microscopic physical parameters and pore size distribution ratio of specimen under superheated steam was less than that under nitrogen atmosphere. For the other pores (>10 nm), the growth rate of microscopic physical parameters and pore size distribution ratio of specimen under superheated steam was greater than that under nitrogen atmosphere. Compared with nitrogen, water vapor was more favorable for pyrolysis of specimen; 4) at a given temperature, the structural parameters (Car/(Car + CO), Car/Hal) of pyrolysis residues of specimen under superheated steam atmosphere were larger than those under nitrogen atmosphere, indicating that the amount of decomposition of aliphatic hydrocarbons and oxygen-containing functional groups was greater than that under nitrogen atmosphere. The research results in this paper can provide useful theoretical guidance and technical support for mining of low-rank clay rich coal.

Establishing the need to model the actual state of stress along rock bolts

Proper design of rock bolt support in underground mines is critical to avoid incidents, accidents and loss of production. The traditional design approach only considers the axial (tensile) capacity and this is clearly not the situation in situ, where a rock bolt is subjected to both axial and shear/bending loads which determines its overall performance and failure behaviour. To demonstrate and analyse the shear displacement in bedded roof, scaled physical models of underground excavation were created. From the models it was found that the shear displacement between the layers depends on the vertical roof deformation and thickness of beds. To analyse the effect of combined loading on rock bolt design for suspension and beam building models, analytical methods were used to calculate the required spacing of rock bolt for a given safety factor. Numerical models were then created using Rocscience RS2 software to establish the stresses on the rock bolt. The results show a significant reduction in safety factor for suspension as demonstrated in an example (reduced from 3.5 to 2.0) and beam building (2.0 to 1.36) when the rock bolt capacities are calculated considering the effect of combined loading as opposed to just the axial or shear loads.

Sand mining on North Stradbroke Island: an Islander view of the rehabilitation of the lands

ABSTRACT Sand mining on North Stradbroke Island has ceased 70 years after it became the Island’s major industry. This article reports conversations with local indigenous people who have lived on the Island all their lives, together with long-term residents – people who have lived with, and worked (directly or indirectly) for the mines, and now must live with the legacy. Views on sand mining changed over time. Initially beach mining was considered benign – tides restored scars, and sand was whiter. Subsequent mining adjacent to the beach and inland resulted in degraded landscapes – failed rehabilitation, introduced plant species, and uncharacteristically-shaped dunes. More recent mine support for Islanders and landscape rehabilitation were considered ‘perfect’. Post-mining issues included unemployment, emigration of younger family members to seek work, depressed house prices trapping people, and tourists destroying the landscape. No Islander interviewed wanted sand mining to cease.

Adapting the Powered Roof Support to Diverse Mining and Geological Conditions

A powered roof support is one of the most important machines of a longwall system. Its basic task is to ensure the safety and continuity of the mining process. The conditions of coal mining process are constantly changing and have significantly deteriorated in recent years, which in turn has also resulted in a significant increase in the requirements for mining support. As a result, it is necessary to develop an appropriate methodology that will facilitate the design and testing process of a power roof support as well as will help to select a roof support adjusted to given conditions. The article presents such a methodology. It is based on forecasted load impacting on a roof support, tests covering selected systems and elements of the section as well as legal conditions regarding the admission of the roof support to operation. This idea was developed in the form of a procedure that, by combining the three areas, should support the decision-making process in the case of different underground conditions. In terms of the expected load impacting on the support, the research team identified the most dangerous phenomena occurring in the rock mass that can generate these loads. Stand tests included impact load and permanent clamping of an excavation. The element that significantly impacts the safety of the support operation is a hydraulic leg, and therefore it was tested together with the safety system and the control system. Model tests were also carried out for the system with a safety valve. The developed concept takes into account legal conditions, which should include test results and different support operating conditions in a more flexible way. The main purpose of the work was to develop a comprehensive methodology for testing and assessing the possibility of using a powered roof support for given mining and geological conditions based on an analysis of safety and control systems. The presented approach is undoubtedly new and original, and can be widely used. It enables better adaptation of the support to given conditions. It also fits the research and activities designed to minimize the presence of miners or service workers in hazardous underground exploitation zones and to improve efficiency and boost sustainable development of the mining industry.

Research on Mechanism and Control of Floor Heave of Mining-Influenced Roadway in Top Coal Caving Working Face

The stability of the surrounding rock is the key problem regarding the normal use of coal mine roadways, and the floor heave of roadways is one of the key factors that can restrict high-yield and high-efficiency mining. Based on the 1305 auxiliary transportation roadway geological conditions in the Dananhu No. 1 Coal Mine, Xinjiang, the mechanism of roadway floor heave was studied by field geological investigation, theoretical analysis, and numerical simulation. We think that the surrounding rock of the roadway presents asymmetrical shrinkage under the original support condition, and it is the extrusion flow type floor heave. The bottom without support and influence of mining are the important causes of floor heave. Therefore, the optimal support scheme is proposed and verified. The results show that the maximum damage depth of the roadway floor is 3.2 m, and the damage depth of the floor of roadway ribs is 3.05 m. The floor heave was decreased from 735 mm to 268 mm, and the force of the rib bolts was reduced from 309 kN to 90 kN after using the optimization supporting scheme. This scheme effectively alleviated the “squeeze” effect of the two ribs on the soft rock floor, and the surrounding rock system achieves long-term stability after optimized support. This provides scientific guidance for field safe mining.

Fuzzy risk prediction of roof fall and rib spalling: based on FFTA-DFCE and risk matrix methods.

The working conditions of underground mining are complex and variable, and roof fall and rib spalling are one of the main types of accidents that can occur. Building an integrated model to evaluate the risk of roof fall and rib spalling is the foundation of mine safety. On the basis of the inherent attributes of event risk, the fuzzy evaluation set and probability of basic events are obtained by using the fuzzy fault tree analysis method based on the sample's fuzzy information. Subsequently, the likelihood of roof fall and rib spalling is determined. Consequence severity data are obtained by using the dynamic fuzzy logic method, and the consequence severity grade of roof fall and rib spalling is evaluated via the dynamic fuzzy comprehensive evaluation method. The event risk level is determined by the risk matrix method. Roof fall and rib spalling in a non-coal mine is analyzed and evaluated by using fuzzy fault tree analysis and dynamic fuzzy comprehensive evaluation. The weak links in the operation of an underground mine are identified by fuzzy fault tree analysis as "mining process, roof management, support and reinforcement." Then, the risk development trend is determined by the dynamic fuzzy comprehensive evaluation method. The risk matrix method is integrated to determine whether the risk level of the mine is "high risk, unacceptable" and expected to deteriorate in the future. The results show the validity and feasibility of the risk analysis and prediction model for roof fall and rib spalling.

Analysis of Failure Characteristics and Strength Criterion of Coal‐Rock Combined Body with Different Height Ratios

In underground mining and roadway support engineering of coal mine, the coal and rock layers bear loads together; therefore, the deformation and mechanical characteristics of the coal‐rock combined bodies are not the same as those of the pure coal or rock bodies. In this paper, conventional triaxial compression tests of coal‐rock combined bodies with different height ratios were conducted. And the stress and deformation characteristics of coal‐rock combined body were studied and the experimental results were analyzed with different strength criteria. The results show that the peak stress, elastic modulus, and strength reduction coefficient of coal‐rock combined body are negatively correlated with the ratio of coal to coal‐rock combination height and positively correlated with the confining pressure; the coal‐rock combination shows obvious ductility under 10 MPa confining pressure. Under the conventional triaxial condition, the shear failure was the main cause of the lateral deformation of the coal body in the coal‐rock combination, which was much larger than that of the rock body. The circle deformation value, volume strain value, and the deformation rate in the postpeak stage of coal‐rock combination are much higher than those in the prepeak stage. Mohr–Coulomb and general Hoek–Brown strength criterion fit the experimental results well.

Geologic data collection and assessment techniques in coal mining for ground control

The identification and mitigation of adverse geologic conditions are critical to the safety and productivity of underground coal mining operations. To anticipate and mitigate adverse geologic conditions, a formal method to evaluate geotechnical factors must be established. Each mine is unique and has its own separate approach for defining what an adverse geological condition consists of. The collection of geologic data is a first critical step to creating a geological database to map these hazards efficiently and effectively. Many considerations must be taken into account, such as lithology of immediate roof and floor strata, seam height, gas and oil wells, faults, depressions in the mine floor (water) and increases in floor elevation (gas), overburden, streams and horizontal stress directions, amongst many other factors. Once geologic data is collected, it can be refined and integrated into a database that can be used to develop maps showing the trend, orientation, and extent of the adverse geological conditions. This information, delivered in a timely manner, allows mining personnel to be proactive in mine planning and support implementations, ultimately reducing the impacts of these features. This paper covers geologic exploratory methods, data organization, and the value of collecting and interpreting geologic information in coal mines to enhance safety and production. The implementation of the methods described above has been proven effective in predicting and mitigating adverse geologic conditions in underground coal mining. Consistent re-evaluation of data collection methods, geologic interpretations, mapping procedures, and communication techniques ensures continuous improvement in the accuracy of predictions and mitigation of adverse geologic conditions. Providing a concise record of the work previously done to track geologic conditions at a mine will allow for the smoothest transition during employee turnover and transitions. With refinements and standardization of data collection methods, such as those described in this paper, along with improvement in technology, the evaluation of adverse geologic conditions will evolve and continue to improve the safety and productivity of underground coal mining.

A Hybrid Data Mining Method for Tunnel Engineering Based on Real-Time Monitoring Data From Tunnel Boring Machines

Tunnel engineering is one of the typical megaprojects given its long construction period, high construction costs and potential risks. Tunnel boring machines (TBMs) are widely used in tunnel engineering to improve work efficiency and safety. During the tunneling process, large amount of monitoring data has been recorded by TBMs to ensure construction safety. Analysis of the massive real-time monitoring data still lacks sufficiently effective methods and needs to be done manually in many cases, which brings potential dangers to construction safety. This paper proposes a hybrid data mining (DM) approach to process the real-time monitoring data from TBM automatically. Three different DM techniques are combined to improve mining process and support safety management process. In order to provide people with the experience required for on-site abnormal judgement, association rule algorithm is carried out to extract relationships among TBM parameters. To supplement the formation information required for construction decision-making process, a decision tree model is developed to classify formation data. Finally, the rate of penetration (ROP) is evaluated by neural network models to find abnormal data and give early warning. The proposed method was applied to a tunnel project in China and the application results verified that the method provided an accurate and efficient way to analyze real-time TBM monitoring data for safety management during TBM construction.

Sentiment on Google Play Android Apps Analytic User Rating Review Through Data Mining Techniques

In the current scenario the data mining plays an important role, where application and domain need data mining support. Everywhere we have seen a lot of Android smartphone users as well as IOS. This paper used several classification techniques used to extract and analyze the dataset from mobile apps. We studied the methods available to classify the number of downloading in minutes and the users' aggregate ratings. The classification involves data classification based on the complete training sample. It also plays an essential role in collecting information and extracting useful information from many mobile phones. There is n number of algorithms available and techniques for the extraction and classification of features. We took four classification methods, i.e., Naive Bayes, Vector Machine, AdaBoost, and neighbor K-Nearest. According to these methods, split ten random samples with 95% data scores in different ways. The AdaBoost method is the best among four because of the scores of AdaBoost AUC-0.495, CA-0.980, F1-0.979, Precision-0.978 and Recall-0.980.

SAERMA: Stacked Autoencoder Rule Mining Algorithm for the Interpretation of Epistatic Interactions in GWAS for Extreme Obesity

SAERMA: Stacked Autoencoder Rule Mining Algorithm for the Interpretation of Epistatic Interactions in GWAS for Extreme Obesity

Boundary condition of the mining support on an example of the arc-inflexible support

Underground structures and tunnels as buildings cover a wide range of the areas in constructions that are closely intertwined and mutually conditioned. The geological environment conditions are a choice of excavation technology, which in turn indirectly affect the pressure level of rock mass and the choice of supporting structure (temporary and permanent). Calculation for the support metal elements capacity is presented in this paper.

Experimental Study on Dynamic Mechanical Properties of Coal Gangue Concrete

In order to study the static and dynamic mechanical characteristics of the coal gangue concrete used in the mine support structure, the compressive strength test, the drop weight impact test, and the Split Hopkinson Pressure Bar (SHPB) test were conducted. The compressive strength, initial and final impacting energy, dynamic strength, and failure characteristic of concrete were obtained of the concrete single‐doped with coal gangue coarse aggregate, single‐doped with coal gangue fine aggregate, and codoped with coal gangue coarse and fine aggregates. The results show that (1) it is feasible that employing coal gangue to replace natural coarse and fine aggregates in concrete can prepare C30 and C40 concrete; (2) the addition of coal gangue fine aggregate has a positive effect on the impact energy of the initial and final cracks of concrete, while the addition of coal gangue coarse aggregate has a negative effect on it; (3) compared with the static strength, the dynamic strength of concrete is improved no matter whether coal gangue is added to concrete; (4) the incorporation of coal gangue coarse aggregate will make the concrete shear surface smooth; (5) at the given impacting pressure, the concrete with coal gangue coarse aggregate has greater particle breakage and those with coal gangue fine aggregate has less. The research of this study can be a reference for the application of gangue concrete in mine support structures.

A Combined Horizontal Parallel Apriori Algorithm and Adaptive Frequent Pattern Growth Algorithm for Big Data Mining

Due to the massive data size and complexness, big data mining using a sole computer is a problematic task. With the rapid increase in the database size, parallel and distributed computing systems can yield better benefits in the data mining applications. Parallelization of the Association Rule Mining (ARM) algorithms is a significant task in the data mining application for effectively mining the frequent itemsets from the large-size databases. These mining algorithms allocate the database in a horizontal manner or increase the number of processors to decrease the overall time necessary for mining the frequent itemsets. In this paper, a combined Horizontal Parallel-Apriori (HP-Apriori) and Adaptive Frequent Pattern (FP) Growth algorithm is proposed to divide the database both horizontally and vertically into four sub-processes, for parallel processing of all four tasks. The Horizontal Parallel-Apriori algorithm increases the speed of the mining process using an index file. Adaptive Binomial Distribution (ABD) is applied to the Frequent Pattern Growth Algorithm to find the minimum support for mining the optimal frequent itemsets. Experimental analysis established that the combined algorithm outperforms in terms of minimizing the overall execution time and increasing the computational speed in high scalability.

MODERN METHODS FOR REDUCING AND OVERCOMING MIN DANGER FOR SHIPS (VESSELS) AND BOATS UKRAINIAN NAVY IN THE BLACK AND AZOV SEAS

This paper considers the problem that exists in the marine space of the Black and Azov Seas and related to the mine danger for warships of Ukraine in certain naval zones of responsibility of the Ukrainian Navy. The authors focused on the fact that the mine danger, which constitutes a real threat to the national security of Ukraine from the sea, not only does not decrease, but also increasesand becomes extremely dangerous.Particular attention was focused on circumstanceswhich might not be known, and were not taken into account when working out decisions on mine defense and mine protectionof the Ukrainian Navy.First of all, this is the existing mine danger in the Black and Azov Seas off the coast of Ukraine, which remained of past wars and post-war active naval activities,as well as from a sea mine threat, which was formed as a result of aggressive actions by the Russian Federation, which threatens Ukraine from the sea. That is, the authors paid special attention to circumstances that might be unknown and were not taken into account earlier when working out decisions on anti-mine defense and anti-mine support for the Ukrainian Navy. This is, first of all, the existing mine danger of the Black and Azov Seas off the coast of Ukraine, which has remained from the past World War II, as well as post-war active naval activities. And secondly, it is preparation and counteraction to possible aggressive manifestations and a mine threat from the side of the country, which constantly threatens Ukraine from the sea. To this end, іn the paper gave specific recommendations on ways to reduce the mine risk for warships of Ukraine and indicated, that in the near future, in Ukrainian Navy it is necessary to activate all existing and well-known components of the mine support system. Ukraine must guaranteedly solve any problems or possible resistance of interested parties in creating the necessary number of mine and mine ships (boats) as part of the Ukrainian Navy.

Application of generalized Hoek–Brown criterion to selection and design of mine support systems for the Oktyabrsky copper–nickel deposit: Case study

Application of generalized Hoek–Brown criterion to selection and design of mine support systems for the Oktyabrsky copper–nickel deposit: Case study

Comparison of K-Nearest Neighbour and support vector machine for choosing senior high school

The aim of this research is to compare K-Nearest Neighbour (KNN) and Support Vector Machine (SVM) algorithm which are used for choosing senior high school recommendation. As we know that education is an important aspect in the development of a nation. The methodology that used in this research is data mining through Knowledge Discovery in Database (KDD) stages, which consist of cleaning, data integration, data selection, data transformation, data mining, pattern evaluation, and knowledge presentation. KNN and SVM are the most common algorithms used in data mining and decision support system. Either KNN or SVM in this research used for classifying the type of senior high school by input parameters, among others national examination score, student interest, and counsellor suggestion. Based on the experiment with several training and testing data, the result shows that SVM is better than KNN. SVM has an accuracy value around 97.1%, while KNN has an accuracy value around 88.5%. And also, SVM has processing time faster than KNN.

Deterministic seismic hazard assessment of coal fractures in underground coal mine: A case study

Mining seismicity induced by coal fractures can cause strong seismic motions in roadway and result in serious seismic hazards to mining personnel and equipment. In order to assess the seismic hazards induced by coal fractures, a deterministic methodology was proposed based on a coal fracture source model and further developed into a numerical program called Mining-induced Seismic Hazard Assessment software (MSHA). The program accepts user-input material constants of in-situ coal seam and calculates the resultant seismic motions in the roadway; the seismic motions were fully verified by a comparison between the numerical and in situ results. The methodology was further applied to assess the seismic hazards in the panel 92201 of the Sanhejian Coal Mine, the seismic hazards were characterized by the peak particle velocity (PPV) and octahedral shear stress (OSS). The results indicate that the tensile strength of coal constitutes the most significant parameter of the coal fracture source model. Moreover, a general and practical conclusion was obtained that the intensity and scope of seismic hazards in roadway are positively related to the tensile strength of coal, and the left and right sides of the roadway might encounter significant seismic damage under impact of coal fracture. The conclusion is useful for mining engineers to identify the potential seismic hazard in the roadway, and therefore make targeted strategies in mining support system.