Artykuły w czasopismach na temat „Mine backfill”
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1
Mitchell, Robert J. "Centrifuge model tests on backfill stability". Canadian Geotechnical Journal 23, nr 3 (1.08.1986): 341–45. http://dx.doi.org/10.1139/t86-048.
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The 6 m diameter, 30 g-tonne geotechnical centrifuge at Queen's University is described. Results from eight model tests, carried out on plain cemented sand samples representing mine backfills, are presented. These data show that the stable prototype backfill heights obtained from centrifuge tests exceed the failure heights predicted from unconfined compression testing by factors averaging about 1.8. This factor is explained by a combination of geometrical and behavioural effects. Still photographs of typical backfill failures in the centrifuge are included and these indicate that unacceptable ore dilution and recovery costs would be associated with the prototype failures in plain cemented tailings backfills. Key words: geotechnical centrifuge, mine backfill, model tests, cemented sand.
2
Hefni, Mohammed, i Ferri Hassani. "Experimental Development of a Novel Mine Backfill Material: Foam Mine Fill". Minerals 10, nr 6 (23.06.2020): 564. http://dx.doi.org/10.3390/min10060564.
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This study aims to develop a novel mine backfill material called foam mine fill (FMF). A cellular structure is achieved by incorporating a premade foam into the backfill mixture using an air-entraining agent. FMF samples were prepared with copper-nickel mine tailings and normal Portland cement. Experiments were designed to investigate the effect of binder dosage, volume of entrained air, and foam mixing time on FMF unconfined compressive strength (UCS) and dry density. Moreover, a qualitative microscopic assessment investigated the effect of foam mixing time on air bubble structure. The pore size distribution and porosity of selected samples were investigated through mercury intrusion porosimetry. Relative to reference samples without entrained air, the UCS of FMF samples was 20–50% lower. However, the concomitant lower dry density (by up to 360 kg/m3) could enhance the safety of the underground working environment, especially in underhand cut-and-fill mining where miners and machinery work beneath the backfilled stope, and lower-density fill material would minimize the adverse effects of potential backfill failure. Prolonged foam mixing time led to a significant loss in UCS and total collapse of the air bubble structure. Other potential applications for FMF are areas where there are tailings shortages and as an alternative to hydraulic fill.
3
Nujaim, Mutaz, Tikou Belem i Albert Giraud. "Experimental Tests on a Small-Scale Model of a Mine Stope to Study the Behavior of Waste Rock Barricades during Backfilling". Minerals 10, nr 11 (23.10.2020): 941. http://dx.doi.org/10.3390/min10110941.
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This paper presents a reduced-scale physical model of a mine stope used to reproduce the underground stope backfilling practiced in some Canadian mines. The objective is to study the geomechanical behavior of the waste rock barricades in interaction with the mine backfill. The instrumentations, along with visual observations and preliminary results, are presented. The main results demonstrated that: (i) the stability of the barricade depends on its physical properties (e.g., size, location, particles gradation and compaction) and the frictional behavior at the barricade/drift walls interface, and (ii) for two backfill formulations, cemented and uncemented, prepared with 70% of solid mass concentration, the volumetric strain due to self-weight consolidation of the backfilled room was higher for uncemented backfill (16%) than for the cemented one (4.5%). In addition, the results highlighted the importance of using shotcrete around the downstream face of the barricade, mostly at the top, to close the gaps and bind the barricade particles, which improves its stability.
4
Emad, Muhammad Zaka, Hani Mitri i Cecile Kelly. "Effect of blast-induced vibrations on fill failure in vertical block mining with delayed backfill". Canadian Geotechnical Journal 51, nr 9 (wrzesień 2014): 975–83. http://dx.doi.org/10.1139/cgj-2013-0305.
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Numerical modelling has long been used as a powerful tool for geomechanics mine design and analysis of such problems as ore dilution. Open stoping mining method with delayed backfill is generally employed for mining steeply dipping tabular ore deposits. Several authors reported that consideration of production blast vibrations on adjacent, exposed backfill faces is crucial for the effective backfill design for minimum ore dilution due to fill failure. In this study, it is shown that blast vibrations can be characterized with dynamic numerical modelling. A FLAC3D dynamic numerical model has been developed for a typical layout of a secondary stope that is being mined next to a previously mined and backfilled primary stope. The numerical simulations are validated by comparing predicted failure geometry with laser-surveyed stope profiles obtained with a cavity monitoring system. It is shown that blast-induced vibrations can be a primary cause for wedge-type failure of the backfill face.
5
Li, Li. "Analytical solution for determining the required strength of a side-exposed mine backfill containing a plug". Canadian Geotechnical Journal 51, nr 5 (maj 2014): 508–19. http://dx.doi.org/10.1139/cgj-2013-0227.
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Backfilling is well known in the mining industry. A basic issue associated with mine backfill design is the determination of the strength of the backfill required to maintain the stability of the backfill body upon removal of a side wall when an adjacent secondary stope is excavated. This task is usually accomplished using a solution proposed by Mitchell et al. in the early 1980s. Recently, this solution has been reviewed and a modified solution has been proposed. These existing solutions, however, were developed for a uniform backfill. In practice, mine stopes are usually divided into primary and secondary stopes. Primary stopes are often backfilled in two stages: a plug pour and a final pour. In many cases, the cement content of the plug pour is higher than that of the final pour. The positive effect of the stronger plug is neglected in both the original and the modified Mitchell et al. solutions. Here, a new analytical solution is developed for estimating the required strength of a laterally exposed backfill by taking the plug into account. The proposed solution reduces to the modified Mitchell et al. solution if the plug pour and final pour have the same cement content. If the plug pour has a cement content higher than that of the final pour, the required backfill strength calculated with the proposed solution is lower than the values estimated with the modified Mitchell et al. solution; the same conclusion can be drawn to the comparison between the proposed solution and the original Mitchell et al. solution when the bond cohesion along the side walls is close to the cohesion of the backfill. Furthermore, the proposed solution indicates that an optimal cohesion ratio between the plug and final pours exists: there is no benefit in using excessively high cement content in the plug pour. It is noted that the proposed solution is valid only for high, narrow backfilled stopes, solutions for low and wide backfilled stopes are under development.
6
Lu, Rong, Fengshan Ma, Jie Zhao, Jianbo Wang, Guilin Li i Bing Dai. "Monitoring and Analysis of Stress and Deformation Features of Boundary Part of Backfill in Metal Mine". Sustainability 12, nr 2 (20.01.2020): 733. http://dx.doi.org/10.3390/su12020733.
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The backfill mining method is widely used in metal mines. A large and thick backfill body has formed in the No.2 zone of Jinchuan Nickel Mine, and its stability is critical for mining safety. In order to study the mechanical behavior of the boundary part of backfill, ground subsidence monitoring, underground filed monitoring of displacement, and stress and numerical simulation were conducted to analyze stress distribution and deformation of backfill. According to underground monitoring, the bed separated displacement has the consistent trend with ground subsidence in the mine area. Based underground stress monitoring, both horizontal and vertical stress of the internal part of backfill is less than the stress boundary part of the backfill. The characteristic of backfill boundary outline is a step-profile. Contact interaction between the surrounding rock and backfill led to complex stress distribution. According to stress monitoring of the boundary points in a numerical model, the multi-peak value of stress development is the major feature of the boundary part of backfill. The multi-peak stress behavior of the boundary part of backfill was influenced by mining depth. The boundary part of backfill deformation influenced the local stability of mining. This article provided a scientific basis for strength design and the support choice of a metal mine by the method of backfill mining.
7
Guo, Li Jie, Ke Ping Zhou, Xiao Cong Yang, Guang Sheng Liu i Wen Yuan Xu. "An Experimental Study on the Mechanical Properties of Cemented Rock-Tailings Fill". Advanced Materials Research 941-944 (czerwiec 2014): 2611–19. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.2611.
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This paper outlines an effective approach to making composite backfill using mine waste material. Composite materials are widely used in many areas of engineering because of their unique structural properties. Cemented rock-tailings are one of the most prevalent materials used for composite backfill because they can effectively make use of mine waste rock and mill tailings that would otherwise be simply considered waste. This backfill method has the capability of maintaining the mine environment while still allowing for continued mine development. An experimental study is being conducted in a cooperative mine research project to investigate the properties of backfill material and specifically the mechanical characteristics of cemented waste rock-tailings fill. This study details the characteristics of the composite backfill aggregate with respect to the compressive strength of the cemented rock-tailings fill and the backfill mix-proportion, as well as outlines a new method of study for cemented rock-tailings fill mechanics. The study results show the compressive strength of cemented rock-tailings fill is dependent mainly on the cement and waste rock content. Ensuring a precise backfill mix proportion can effectively reduce the cement dosage, thereby decreasing the backfill cost realized for the mine.
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Zhao, Xin-yuan, Xin-wang Li, Ke Yang, Zhen Wei i Qiang Fu. "The segmental subsidence structure with immediate roof of gob side entry retaining in backfill mining". Energy Exploration & Exploitation 39, nr 4 (15.03.2021): 1262–82. http://dx.doi.org/10.1177/0144598721996540.
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When gob side entry retaining is carried out in backfill mining, the roof will show different subsidence morphology due to the difference of compactness and supporting force of the backfill body at different positions. This paper analyzed the immediate roof subsidence structure under two extreme conditions, constructed the roof segmented subsidence structure and the mechanical model of roadside backfill body, and used FLAC3D software to investigate the roof migration and the force law of the roadside backfill body under the conditions of different goaf backfilled rates, different width and strength of roadside backfill body. Finally, the backfill practice of a mine in Shandong Province of China is taken as an example for analysis. The results show that the segmented subsidence structure of the immediate roof is related to the mechanical properties of the roadside backfill body and the goaf backfill body. When the backfilled rate of goaf decreases from 95% to 70%, the width of roadside backfill body decreases from 5 m to 1 m, and the elastic modulus decreases from 10 GPa to 0.5 GPa, the greater difference in the subsidence and inclination of the immediate roof on both sides of the roadside backfill body is, the more obvious the segmented subsidence structure characteristics of the immediate roof are, and the greater force on the roadside backfill body will be, the more unfavorable it is to maintain the stability of the roadway surrounding rock and the roadway backfill body. Therefore, when gob side entry retaining is carried out in backfill mining, the surrounding rock structure and the force on roadside backfill body should be considered comprehensively.
9
Jaouhar, El Mustapha, i Li Li. "Effect of Drainage and Consolidation on the Pore Water Pressures and Total Stresses within Backfilled Stopes and on Barricades". Advances in Civil Engineering 2019 (12.05.2019): 1–19. http://dx.doi.org/10.1155/2019/1802130.
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The pore water pressures (PWPs) and total stresses during the placement of a slurried backfill in underground mine stopes are the key parameters for the design of barricades, built to retain the backfill in the stopes. They can be affected by the drainage and consolidation of the backfill. Over the years, several studies have been reported on the pressure and stresses in backfilled stopes by accounting for the drainage and consolidation. Most of them focused on the pressure and stresses in the stopes, few specifically on the barricades. The effect of the number of draining holes commonly installed through the barricade has never been studied. In this paper, the influence of hydraulic properties and filling rate of the backfill, stope size, barricade location, and number of draining holes is systematically investigated with numerical simulations. The results show that the stresses in the backfilled stope and on the barricade largely depend on the filling rate, hydraulic conductivity, and Young’s modulus of the backfill. The draining holes can significantly decrease the PWP, but only slightly the total stresses on the barricades in short term.
10
El Mkadmi, Nawfal, Michel Aubertin i Li Li. "Effect of drainage and sequential filling on the behavior of backfill in mine stopes". Canadian Geotechnical Journal 51, nr 1 (styczeń 2014): 1–15. http://dx.doi.org/10.1139/cgj-2012-0462.
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Underground backfilling offers significant economic and environmental advantages to mining operations. There is however a limited knowledge and understanding of how the backfill behaves within mine stopes, which creates some concern regarding the risk of accidents with potentially serious consequences. It is thus important to investigate further the response of backfill to ensure safe working conditions and optimize the filling sequence. This paper presents key results from a numerical study aimed at analyzing the hydrogeotechnical response of backfill in a narrow vertical stope. The simulations illustrate how stresses are influenced by stope geometry, water drainage, and filling rate. Three main cases are presented here to illustrate these effects; namely, (i) simulation of dry (or drained) backfill, (ii) a rapidly filled stope with progressive drainage and consolidation, and (iii) sequential backfill placement with different filling rates. The third case includes a simulation with evolving properties due to the binder added to the backfill. The results from the numerical analyses show that arching effects develop within narrow backfilled stopes because of the stiffness contrast between the rock and the fill material. This can produce a significant reduction of the stresses (horizontal and vertical) in comparison with the overburden pressure. The simulation results also show the development of excess pore-water pressures after the placement of the saturated backfill within the stope. Drainage tends to reduce these pressures and increase the frictional stresses along the rock walls. The sequentially filled stope simulations show that a rapid filling rate produces much higher total stresses and excess pore-water pressures, compared to slower rates. The simulation of the cemented backfill, with evolving properties, indicates that the progressive changes can have a significant effect on the total and effective stresses in the stope. A discussion follows on the implications of these results.
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Falaknaz, Nooshin, Michel Aubertin i Li Li. "Numerical investigation of the geomechanical response of adjacent backfilled stopes". Canadian Geotechnical Journal 52, nr 10 (październik 2015): 1507–25. http://dx.doi.org/10.1139/cgj-2014-0056.
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Backfilling of mine stopes helps provide a safe workplace underground. The interaction between the backfill and surrounding rock mass has to be evaluated to ensure the secure application of backfill. This critical issue has led to much research on the stress state in single (isolated) backfilled stopes. However, the stress distribution in multiple openings that interact with each other has not yet been investigated as thoroughly. In this paper, the authors are using numerical simulations to evaluate the response of two adjacent backfilled stopes created in sequence, with a new assumption that is based on an explicit relationship between Poisson’s ratio and the internal friction angle of the backfill; as shown here, the use of this relationship can significantly modify the stress state in backfilled stopes. The simulation results, presented in terms of stresses, displacements, and strains, illustrate the influence of different parameters including backfill strength, pillar width, stope depth, rock mass stiffness, natural stress state, and excavation and filling sequence. Complementary aspects are also considered. A discussion follows on some of the characteristics and limitations of this investigation.
12
Wang, Mei, Lang Liu, Liu Chen, Xiaoyan Zhang, Bo Zhang i Changfa Ji. "Cold Load and Storage Functional Backfill for Cooling Deep Mine". Advances in Civil Engineering 2018 (5.07.2018): 1–8. http://dx.doi.org/10.1155/2018/5435214.
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Considering the deep mining heat-hazard problem, the concept and academic idea of cold load and storage (CLS) functional backfill applied on deep mine cooling was put forward. Firstly, according to characteristics of filling mining, a method of cooling stopes with CLS phase changing backfill which is made from the backfill material with CLS phase change material (PCM) was proposed. The working process, cooling physics, and the economic and safety benefits of CLS phase changing backfill were produced. Secondly, the theory system of cooling with CLS phase changing backfill was built. The theoretical basis of the key problems involved was investigated and analyzed which concluded heat transfer, fluid mechanics, and backfill mechanics. Lastly, the technology system of cooling with CLS phase changing backfill was established on the basis of the required technical assistance. It includes four parts: the backfill material design, the backfill material conveying way design, the stope temperature control scheme design, and the strength of cemented tailings backfill analysis. The idea of applying CLS phase changing backfill on cooling deep mine stopes and its theory and technology systems provide a scientific research and suitable development direction for deep mine cooling.
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Qiu, Huafu, Fushun Zhang, Lang Liu, Dongzhuang Hou i Bingbing Tu. "Influencing Factors on Strength of Waste Rock Tailing Cemented Backfill". Geofluids 2020 (19.10.2020): 1–7. http://dx.doi.org/10.1155/2020/8847623.
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Tailing cement filling is an important development direction in mine filling, as it is a green and environmentally friendly method for efficiently treating solid waste in mines. Adding a certain amount of waste rock can effectively improve the backfill strength and better meet the filling strength requirements. To address the use of waste rock tailings in cemented filling materials, a uniaxial compression test was carried out on backfills with different cement/sand ratios and waste rock contents, and the influence of the cement/sand ratio and waste rock content on the strength of the backfill was studied. This study found that when the waste rock content is certain, the strength of the backfill increases with the increase in the cement/sand ratio, and the increase in strength slows with the increase in the cement/sand ratio until the strength of the backfill reaches a limit and no longer increases. When the cement/sand ratio is constant, the strength of the backfill first increases and then decreases as the waste rock content increases. When the cement content is constant, the addition of a certain amount of waste rock reduces the specific surface area of the solid materials in the backfill, increases the amount of cement per unit area, and improves the strength of the backfill. When the waste rock content is too high, due to the large particle size of the waste rock, the tailings cannot completely wrap around the waste rock, resulting in a weakening of the cement in the backfill, which reduces the strength of the backfill. This study found that the waste rock content and the cement/sand ratio in the backfill have a significant impact on backfill damage. The damage is mainly caused by insufficient cement strength. The presence of waste rock will change the original direction of crack propagation, resulting in more crack bifurcation, and the form of the destruction surface on the backfill is complicated and diverse.
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Xie, Jincheng, Dengpan Qiao, Runsheng Han, Tao Deng i Jun Wang. "New Definition of Ultrafine Particles in Mine Paste and Its Relationship with Rheological Properties". Advances in Civil Engineering 2021 (30.04.2021): 1–11. http://dx.doi.org/10.1155/2021/5560899.
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Mine backfill paste is generally composed of tailings and coarse aggregates. In engineering practice, the definitions in fill material classification are vague. In this paper, the size range of ultrafine particles is defined by the Stokes sedimentation test and hydraulic coarseness method. The size range of ultrafine particles is affected not only by the geometric size of the particles but also by the physical characteristics of the particles themselves. This definition has more comprehensive considerations and stricter physical and mathematical significance than the traditional definition of ultrafine particles based only on size. There is a strong correlation between ultrafine particles in fill materials and the rheological properties of the mine backfill paste. In this study, through experiments and correlation analysis, it was found that the content of ultrafine particles is positively correlated with the plastic viscosity of the mine backfill paste, and its growth range is exponential. The coarse aggregate content is positively correlated with the yield stress of the mine backfill paste. A regression analysis model was established for the rheological properties of mine backfill paste. The model has few factors and high correlation, so it can simply and efficiently predict the rheological properties of mine backfill paste and guide engineering practice.
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Chang, Qingliang, Jianhang Chen, Huaqiang Zhou i Jianbiao Bai. "Implementation of Paste Backfill Mining Technology in Chinese Coal Mines". Scientific World Journal 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/821025.
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Implementation of clean mining technology at coal mines is crucial to protect the environment and maintain balance among energy resources, consumption, and ecology. After reviewing present coal clean mining technology, we introduce the technology principles and technological process of paste backfill mining in coal mines and discuss the components and features of backfill materials, the constitution of the backfill system, and the backfill process. Specific implementation of this technology and its application are analyzed for paste backfill mining in Daizhuang Coal Mine; a practical implementation shows that paste backfill mining can improve the safety and excavation rate of coal mining, which can effectively resolve surface subsidence problems caused by underground mining activities, by utilizing solid waste such as coal gangues as a resource. Therefore, paste backfill mining is an effective clean coal mining technology, which has widespread application.
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Hefni, Mohammed, i Ferri Hassani. "Effect of Air Entrainment on Cemented Mine Backfill Properties: Analysis Based on Response Surface Methodology". Minerals 11, nr 1 (15.01.2021): 81. http://dx.doi.org/10.3390/min11010081.
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As part of an extensive research program exploring the potential benefits of using air-entraining admixtures in mine backfill, the experimental study presented in this paper investigates the effect of cement and entrained air dosages on mine backfill unconfined compressive strength (UCS), fresh density, and dry density. Backfill specimens were prepared using silica sand, normal Portland cement, water, and an entrained air admixture. An experimental design with response surface methodology was adopted to develop predictive mathematical models and analyze the results. The results demonstrated that an entrained air dosage of 3.5% could improve the UCS of the mine backfill owing to better dispersion of cement particles. However, a further increase in the dosage reduced the UCS as well as the fresh and dry densities by approximately 200 and 120 kg/m3, respectively. Study results imply that using air-entraining admixtures can potentially enhance mine backfill flowability and reduce the density, thus providing safer and more sustainable working conditions in an underground mining environment.
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Zhang, Xinguo, Jinhai Zhao, Lin Xin, Kun Wang i Haiyang Pan. "Monitoring and Assessment of Cemented Paste Backfill Containing Coal Gangue and Fly Ash in an Underground Mine". Advances in Materials Science and Engineering 2021 (23.02.2021): 1–15. http://dx.doi.org/10.1155/2021/5946148.
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Cemented coal gangue paste backfill (CCGPB) containing coal gangue and fly ash is a backfilling technique newly developed in coal mines in China that allows environmentally hazardous products, such as gangue and fly ash, to be reused in underground stopes. CCGPB materials provide efficient ground support for the caving of strata and reduce surface subsidence. In this paper, field monitoring of CCGPB properties was conducted in an underground coal mine, which mainly included the measurement of the longwall face temperature, humidity, CCGPB internal hydration temperature, stress conditions inside the backfills, and displacement. First, the components of the backfills, paste technique, slurry generation procedures, coalfield geology, and mining conditions were introduced. Then, a monitoring system was designed in the field. An online monitoring system was installed. The results of the field monitoring showed that the curing temperature significantly varied, i.e., from 26°C near the main gate to 37°C near the tailgate. The curing humidity had the same trends, increasing from 60% relative humidity (RH) near the main gate to 81% RH near the tailgate. The internal hydration process of the paste was divided into four stages, i.e., the rapid hydration stage, slower hydration stage, rapid decline hydration stage, and relatively stable stage. The highest hydration temperature was 50°C, which was measured on the second day after the backfill process. The temperature approached stability at 41°C. The evolution of the roof stress applied on the CCGPB was divided into four stages: the development stage, regulation stage, rapid growth stage, and relatively stable stage. The maximum roof loading was 12 MPa in the middle of the longwall face. The deformation of the backfill experienced four stages, i.e., the rapid deformation stage, slow deformation stage, relatively stable stage, and long-term stable stage. The maximum deformation was 104.3 mm, appearing in the middle of the face. In addition, the compression ratio of the backfill was approximately 4%. The results of this study showed that the working conditions of backfills in the field were different from those in the laboratory. This paper provides guidance for the design of the CCGPB technique and the predictions of surface subsidence induced by the production process of underground mining.
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Li, Xibing, Dongyi Wang, Chongjin Li i Zhixiang Liu. "Numerical Simulation of Surface Subsidence and Backfill Material Movement Induced by Underground Mining". Advances in Civil Engineering 2019 (17.06.2019): 1–17. http://dx.doi.org/10.1155/2019/2724370.
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Surface subsidence induced by underground mining is one of the challenging problems in mining engineering, which can destroy ground surface buildings and cause huge economic losses to the mine. In this study, a two-dimensional numerical model, established by the discrete element method code PFC2D, was adopted to investigate the mechanical mechanism of surface subsidence and backfill material movement induced by underground mining in the Hongling lead-zinc mine. In the first simulation case, the ore body was excavated from the ground surface to the mining level 705 m by the sublevel caving mining method, and the stress evolution during the mining process was analyzed to reveal the mechanical mechanism of surface subsidence. In the second and third simulation cases, the mined-out areas above 905 m were backfilled by the noncemented tailings and an insulating pillar was reserved beneath the backfill material, and then the deep ore body was excavated by two different mining methods to study the movement law of the backfill material and rock strata induced by underground mining. The numerical simulation results show that when the sublevel caving mining method is adopted, underground mining can induce toppling failures in the hanging wall and lead to a large collapse pit in the ground surface. After the toppling failures in the hanging wall, the collapsed waste rock in the mined-out area can provide support force for the surrounding rock and restrict the further collapse of the hanging wall. Furthermore, when the cut-and-fill mining method is adopted for the excavation of deep ore body, the insulating pillar can restrict the horizontal displacement of surrounding rock and maintain the stability of the backfill material. The cut-and-fill mining method can efficiently control the surface subsidence and prevent the occurrence of collapse pit in the ground surface and is recommended for the Hongling lead-zinc mine to solve the surface subsidence problem.
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Dang, Vu Hai, i Manoon Masniyom. "The Effect of High Salinity Water to the Compressive Strength of Mine Backfill Material". Key Engineering Materials 777 (sierpień 2018): 554–58. http://dx.doi.org/10.4028/www.scientific.net/kem.777.554.
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The effect of the high salinity water on the compressive strength of mine backfill was studied. Two types of salinity water: saturated and unsaturated brines were employed to mix with mine backfill materials, and the results were compared. The one with saturated brine had high salt content of 400 g/l while the other had 200 g/l. The results showed that compressive strength decreased with increasing salt content. The mine backfill with high salt content (saturated brine) exhibited the poorest compressive strength in which its strength decreased to approximately 50-70 % of the original strength gained from the backfill samples based on water without salt. Additionally, the optimal saline water solid ratio was 0.2.
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Wang, Yi Ming, Ming Qing Huang, Ai Xiang Wu, Gao Hui Yao i Kai Jian Hu. "Rock Backfill and Hazard Control of Abandoned Stopes: A Case Study". Applied Mechanics and Materials 368-370 (sierpień 2013): 1726–31. http://dx.doi.org/10.4028/www.scientific.net/amm.368-370.1726.
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Goafs formed in mine-out areas threat the underground mines owing to possibilities of rock burst and surface subsidence. This paper aims to discuss the feasibility, design and construction of waste rock backfill in abandoned stopes. Based on goafs distribution and stabilities in the White Bull Mine, rock backfill system with a total volume of 362,000 m3in 8 gobs was designed and carried out. The system included technologically and economically feasible stopes, conveying equipments of tramcars, rock transfer by electric rakes, haulage network and mining workings. Field effects showed that rock backfill was applicable to control potential hazards. With rock filling, goaf utilization rates ranged from 60% to 70%, which helped to control adjacent rock movement, eliminate rock burst and surface subsidence. Additionally, backfill construction reduced the lift and transportation costs of rocks by about 50%, which further lowered the land usage of surface dumping.
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Gao, Huadong, Baifu An, Zhen Han, Yachao Guo, Zeyu Ruan, Wei Li i Samuel Zayzay. "The Sustainable Development of Aged Coal Mine Achieved by Recovering Pillar-Blocked Coal Resources". Energies 13, nr 15 (31.07.2020): 3912. http://dx.doi.org/10.3390/en13153912.
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China faces the problem of depletion of its coal resources, and a large number of mines are becoming aged mines. Demand for coal, however, still increases due to the growth of China’s economy. Energy shortage might restrict the sustainability of China’s national economy. As one contribution to a solution, this paper proposes the innovative exploitation method of solid backfill coal mining (SBCM) technology to exploit parts of pillar-blocked (residual coal pillar resources under industrial square, RCPRIS) that protect industrial facilities. Thus, blocked coal resources may be converted into mineable reserves that improve the recovery ratio of mine resources. Also, waste would be removed from the surface reducing hazards of environmental pollution. Based on the case of the Baishan Coal Mine in Anhui, China, numerical simulation is used to study the size of shaft-protecting coal pillars (SPCP) required at different backfill ratios. Results show that the disturbance to a shaft caused by exploitation decreases with the increase of the backfill ratio. When using SBCM to exploit RCPRIS under the condition of 80% backfill ratio, compared with the caving method, a lot of pillar-blocked coal resources would be freed. The life of Baishan Coal Mine would be prolonged, resulting in appreciable social, environmental, and economic benefits.
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Hao, Jian, Yongkui Shi, Jiahui Lin, Xin Wang i Hongchun Xia. "The Effects of Backfill Mining on Strata Movement Rule and Water Inrush: A Case Study". Processes 7, nr 2 (29.01.2019): 66. http://dx.doi.org/10.3390/pr7020066.
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Backfill mining is widely used to control strata movement and improve the stress environment in China’s coal mines. In the present study, the effects of backfill mining on strata movement and water inrush were studied based on a case study conducted in Caozhuang Coal Mine. The in-situ investigation measured abutment pressure distribution (APD), roof floor displacement (RFD), and vertical stress in the backfill area. Results are as follows: (i) The range and peak of APD, RFD, and vertical stress in the backfill area are smaller than in traditional longwall mining with the caving method. (ii) Backfill mining could change the movement form and amplitude of overburden and improve the ground pressure environment. (iii) Floor failure depth (FFD) is much smaller in backfill mining. Backfill mining can be an effective method for floor water inrush prevention.
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Wang, Yumin, Yucheng Huang i Yuxin Hao. "Experimental Study and Application of Rheological Properties of Coal Gangue-Fly Ash Backfill Slurry". Processes 8, nr 3 (3.03.2020): 284. http://dx.doi.org/10.3390/pr8030284.
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From the perspective of resource recovery and environmental protection, coal gangue-fly ash cemented backfill coal mining has become an important direction for the green development of coal mines in recent years. Analysis of the rheological parameters of backfill slurry is the basic principle to design a backfill pipeline system. Coal gangue-fly ash backfill slurry has a mass concentration of 76% to 79% and a maximum particle size 20 mm. Therefore, it is difficult to use conventional rheometers for experimental analyses of the rheological parameters of such fluids. We developed a rheometer for high-concentration coal gangue backfill slurry (HCGS rheometer) based on the coal gangue-fly ash backfill practice of Gonggeying Mine, and analyzed the rheological properties of the backfill slurry. The experimental results showed that the Reynolds number of the coal gangue-fly ash backfill slurry was much smaller than the critical Reynolds number, indicating the flow state in the pipeline was laminar. Based on these results, it may be more appropriate to control the mass concentration to 77% to 78%, and the suggested fly ash content is 25%. This work provides a scientific basis to optimize the backfill parameters and pipeline system in coal mines.
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Zhang, Xiaoyan, Yuhang Jia, Mei Wang i Lang Liu. "Experimental Research on Heat Transfer and Strength Analysis of Backfill with Ice Grains in Deep Mines". Sustainability 11, nr 9 (28.04.2019): 2486. http://dx.doi.org/10.3390/su11092486.
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In deep mines, two urgent problems are a high temperature thermal environment and solid waste. Filling the goaf with slurry mixed with ice grains is an effective way to solve these two problems simultaneously. The thermal property and mechanical property of the ice-added backfill have a great influence on the cooling effect in the deep mine. In this study, an experimental facility for measuring the temperature distribution of ice-added backfill slurry was established, and the temperature of backfill slurry with different proportions was measured. Then, the thermal properties of temperature distribution and cooling capacity and the mechanical property of uniaxial compressive strength of the backfill specimens were analyzed, and the results indicated the following: firstly, the cooling capacity of ice-added backfill specimens is negatively related with the slurry concentration C and is positively related with the ice-water ratio Ω; secondly, the strength of backfill specimens is affected by the slurry concentration C and ice-water ratio Ω by a contrary law compared to the cooling capacity; thirdly, ice-added backfill slurry with an ice-water ratio Ω of 1:1 has the best mechanical property after solidification. The effects of the slurry concentration and ice-water ratio on the thermal and mechanical properties were analyzed, and the results indicated that the optimum proportion of ice-added backfill slurry is a slurry concentration of 74% and an ice-water ratio of 1:1 in the present research range. This study is significant for the deep mine cooling method with ice-added backfill.
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Emad, Muhammad Zaka. "Numerical modelling approach for mine backfill". Sādhanā 42, nr 9 (24.07.2017): 1595–604. http://dx.doi.org/10.1007/s12046-017-0702-0.
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Li, Mao Hui, Zhi Qiang Yang, Qian Gao i You Tuan Wang. "The Orthogonal Test and Optimal Decision for the Development of New Backfill Cementing Materials Based on the Rod Milling Sand". Advanced Materials Research 962-965 (czerwiec 2014): 1100–1105. http://dx.doi.org/10.4028/www.scientific.net/amr.962-965.1100.
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The experiment uses lime, desulfurization ash, slag and other solid wastes with mirabilite and NaOH as the admixture for Jinchuan mine rod milling sand to get a new backfill cementing materials that can replace the cement materials. There obtains the influence of activators to strength of the new backfill cementing materials’ body through the orthogonal experiment. The MATLAB genetic programming is exploited for getting the regression function of compressive strength and shrinkage rate for the new backfill cementing materials. Using the genetic algorithm to optimize the constrained regression functions that can get the best combinations of the activators, Finally. The results show that the compressive strengths (28d, 7d, 3d) of new backfill cementing materials are 6.73MPa, 4.03MPa and 1.00MPa when the lime, desulfurization ash, mirabilite, NaOH and slag are 7.05%, 16.32%, 3.062%, 1.08% and 72.48%. The optimal results conform to the requirements of the Jinchuan mine filling strength, which lays a foundation for further industrial test of new backfill cementing materials in Jinchuan mine.
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Li, Yan. "Evaluation of Backfill Operation Models Using SBSC and IFAHP Approach". Advances in Civil Engineering 2021 (22.04.2021): 1–11. http://dx.doi.org/10.1155/2021/6693021.
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As the mine backfill is recognized as one promising technique for the sustainable development, it is crucial to explore the backfill operation mechanism for the mining industry. At present, the self-management and outsourcing model are generally selected to apply in backfill operation and management worldwide. The advantages are insufficient from the strategic and sustainable perspective. Therefore, the study proposes joint venture alliance and concerns the superiority on mine backfill management. In order to evaluate the models, this study puts forward the integrated method which involves combination of SBSC and IFAHP. A strategic and hierarchical framework of SBSC on the basis of sustainability is formulated, which includes 6 perspectives and 16 secondary indexes. Simultaneously, the IFAHP approach is used for determination of the weights of indexes and calculation of the final score, which enables to assess mine backfill operation activity more objectively. The results show that the self-management model provides little advantages whereas the outsourcing model is the better operation mechanism. By contrast, joint venture alliance is rated as the optimal backfill operation model of the mining industry. The research findings of this study would help the mining industry to evaluate objectively and make an appropriate decision on the backfill operation model in the mining industry.
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Wang, You Tuan, Zhi Qiang Yang, Qian Gao i Mao Hui Li. "Utilization of Jinchuan Unclassified Tailings in Mine Filling". Advanced Materials Research 1073-1076 (grudzień 2014): 2158–62. http://dx.doi.org/10.4028/www.scientific.net/amr.1073-1076.2158.
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In order to utilize the unclassified tailings and reduce the cost of backfill in Jinchuan mine, compressive strength experiments were conducted by taking unclassified tailings as aggregating material. The influence of unclassified tailings on compressive strength was studied, and the influence of unclassified tailings on Hydration products and microstructures was analyzed by XRD and SEM also. The results show that the fine particle size and higher mud content of unclassified tailings have adverse effect on early strength, especially on 3d compressive strength, but it can mprove the long-term strength. The hydration products of the new backfill cementitious materials is mainly C-S-H gel, the flocculent C-S-H gel form dense gel-structure and bond the aggregates together form the high mechanical strength. With the new backfill cementitious materials can achieve 30% utilization of unclassified tailings in Mine Filling, and attained the goal of reducing backfill costs and protecting the environment.
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Huang, Gang, Si Jing Cai, Ya Dong Zhang i Di Wu. "Experimental and Modeling Study on the Strength of Tailings Backfill in Underground Mine". Applied Mechanics and Materials 522-524 (luty 2014): 1390–93. http://dx.doi.org/10.4028/www.scientific.net/amm.522-524.1390.
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Taking backfill material of underground mine as the object of study, this paper conducts the research on its strength characteristics by using uniaxial compressive strength testing machine at different cement-sand mass ratio and curing time and mass concentration which the method of experiment and theory analysis were used. The model of predicting the strength of tailings backfill was introduced, and its results were identical with the expreimental test after comparing. Therefore, the mathematical model can be used to estimate the strength of tailings backfill after assigning the specific value of tailing backfill. The tested results show that the uniaxial compressive strength of backfill rose with the increase of its concentration, cement-sand ratio, and the curing time; the strength of backfill was not enough to sustain the stope if the curing time is short and the cement-sand ratio is small.
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Hefni, Mohammed, i Maaz A. Ali. "The Potential to Replace Cement with Nano-Calcium Carbonate and Natural Pozzolans in Cemented Mine Backfill". Advances in Civil Engineering 2021 (6.03.2021): 1–10. http://dx.doi.org/10.1155/2021/5574761.
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The effectiveness of mine backfilling depends on the properties of its constituents. The high cost of cement, which is commonly used as a binder in mine backfill, has led researchers to seek alternatives to partially replace it with other binders. This study investigated the potential to use nano-calcium carbonate (NCC) and natural pozzolans (zeolite and pumice) along with Portland cement (PC) in mine backfill. Two types of experimental samples were prepared: (1) gold tailings and silica sand to investigate the effect of NCC and (2) nickel tailings to investigate the effect of natural pozzolans. The unconfined compressive strength (UCS) was measured for samples cured for up to 56 days. Moreover, selected samples were subject to mercury intrusion porosimetry to investigate microstructural properties. Results show that addition of NCC did not improve the UCS of backfill prepared with gold tailings and cured for 28 days, whereas a dosage of 1% NCC in backfill samples prepared with silica sand improved UCS by 20%, suggesting that the gold tailings negatively affected strength development. Natural pozzolans, in particular, 20% zeolite, had 24% higher UCS after 56 days of curing compared to samples prepared with PC and thus have the potential to partially replace cement in mine backfill.
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Zheng, Juanrong, Lijie Guo, Xiaoxiao Sun, Wenchen Li i Qi Jia. "Study on the Strength Development of Cemented Backfill Body from Lead-Zinc Mine Tailings with Sulphide". Advances in Materials Science and Engineering 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/7278014.
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The unconfined compressive strength (UCS) development of cemented backfill materials for lead-zinc mine tailings with sulphide was studied. The results showed that the UCS of the cemented backfill body with ordinary Portland cement (OPC) as binder decreased in the later curing days, regardless of particle size. Under the same conditions, the higher the OPC content, the higher the UCS of the cemented backfill body, and the UCS of the cemented backfill body began to decrease at the longer curing days. Under the same conditions, the finer the tailings, the lower the UCS of the cemented backfill body at each age, and the UCS of the cemented backfill body began to decrease at the earlier curing age. X-ray diffraction analysis (XRD) showed that the reduction of the UCS of the cemented backfill body was related to the formation of an expansive substance (expansive gypsum) in the cemented backfill body, which led to the cracking of the test sample. In the cemented backfill materials of coarse tailings of lead-zinc mine, the composite binder formed by OPC and calcined kaolin (CK) containing metakaolin was used; the amount of calcium hydroxide, the hydration product of cement, was reduced or eliminated due to the pozzolanic reaction of metakaolin; and the amount of expansive gypsum was reduced or eliminated, so the UCS of the cemented backfill body increased within 360 days of curing.
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Zhao, Xinyuan, Xinwang Li, Ke Yang i Zhen Wei. "The Spatiotemporal Characteristics of Coupling Effect between Roof and Backfill Body in Dense Backfill Mining". Geofluids 2021 (2.02.2021): 1–15. http://dx.doi.org/10.1155/2021/6684237.
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Backfill mining has become an important part of coal mine green mining technology. In this paper, the spatiotemporal characteristics of coupling effect between the roof and dense backfill body were analyzed by theoretical analysis and similar simulation test, and Xingtai Mine in China was taken as an engineering case for verification. The results show that the larger subsidence of the roof is, the stronger the supporting capacity of the backfill body is, and the interaction between the two is more obvious, thus showing a coupling effect. This coupling effect presents a regular variation with the increase of backfill distance and time, that is, the coupling degree of roof and backfill body is high in the middle of goaf and low in the vicinity of the coal pillar in spatial distribution, and the coupling behavior of roof and backfill body continues to occur slowly with time. Through the monitoring of stress and displacement in the engineering site and the analysis of borehole observation results, the spatiotemporal coupling effect between roof subsidence and backfill support is fully verified. The research results are of great significance to the control of surrounding rock in backfill mining, the study of the mechanical aging characteristics of backfilling materials, and the optimization of backfill body support performance.
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Yu, Yihe, Liqiang Ma i Dongsheng Zhang. "Characteristics of Roof Ground Subsidence While Applying a Continuous Excavation Continuous Backfill Method in Longwall Mining". Energies 13, nr 1 (23.12.2019): 95. http://dx.doi.org/10.3390/en13010095.
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Activities of traditional longwall mining will result in ground subsidence and therefore cause issues such as damages to buildings and farmlands, water pollution and loss, and potential ecological and environmental problems in the mining region. With advantages of the longwall backfill mining method, as well as the room and pillar mining method, a continuous excavation and continuous backfill (CECB) method in longwall mining is recommended to effectively control the ground subsidence. In this method, mining roadways (MRs) are initially planned in a panel, and then they are excavated and backfilled in several stages until the whole panel is mined out and backfilled. According to the geologic conditions of an underground coal mine, and the elastic foundation beam theory, a mechanical model was built to study the subsidence of the roof while using this new mining method. In addition, methods to calculate roof subsidence in various stages in CECB were also provided. The mechanical parameters of backfilling materials, which were used in the theoretical calculation and the numerical analysis for mutual check, were defined through analyzing the stability conditions of the coal pillars and the filling bodies. The control effect for the ground subsidence of using the newly proposed mining method was analyzed based on both simulation results and site monitoring results, including the ground subsidence, horizontal displacement, tilt, curvature and horizontal strain. This research could provide suggestions to effectively control ground subsidence for a mine site with similar geologic conditions.
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Han, Bin, Shengyou Zhang i Wei Sun. "Impact of Temperature on the Strength Development of the Tailing-Waste Rock Backfill of a Gold Mine". Advances in Civil Engineering 2019 (16.11.2019): 1–9. http://dx.doi.org/10.1155/2019/4379606.
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This study investigated the influencing rules of curing temperature (5, 10, 16, and 20°C), cement ratio (8%, 10%, 12%, and 14%), and mass concentration (70%, 73%, 74%, and 75%) on the strength of backfill. In addition, a scanning electron microscope (SEM) is employed to analyze the microtopography of the backfill. Experimental results indicate that the uniaxial compressive strength (UCS) of the backfill decreases as the curing temperature diminishes; temperature substantially influences the earlier strength of backfill (it is much significant below 10°C). In addition, as the cement ratio rises, the critical point for the impact of temperature on strength gradually moves toward a low-temperature zone; in pace with the slurry mass concentration increase, the compressive strength of the backfill also rises and its rate of increase enlarges after going beyond the critical concentration. In case the curing temperature is lower than 10°C, the extent of hydration is also low inside the backfill. Through experiments, the critical concentration of slurry in the Jinying gold mine is determined as 73%, and the critical interval of the cement ratio ranged between 10% and 12%. Corresponding measures can be taken to increase the strength of backfill in the Jinying Gold Mine by 129.9%. As a result, backfill collapse is effectively controlled.
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Helinski, Matthew, Martin Fahey i Andy Fourie. "Coupled two-dimensional finite element modelling of mine backfilling with cemented tailings". Canadian Geotechnical Journal 47, nr 11 (listopad 2010): 1187–200. http://dx.doi.org/10.1139/t10-020.
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Mine backfilling is a process whereby mine tailings mixed with small amounts of cement are placed hydraulically into mined-out voids (“stopes”) to stabilize the rockmass and allow full extraction of adjacent ore. A containment barricade is constructed to block the access point at the base of the stope, the design of which requires calculation of the total stress on the barricade during and following filling. For fine-grained backfill containing cement, the rate of development of stresses is governed by the rates of filling, consolidation, and cement hydration, each with its own timescale. As “consolidation” in backfill undergoing hydration can be dominated by “self-desiccation”, this mechanism must also be incorporated. Interaction between the backfill and the stope walls (“arching”) also has an influence. The paper describes a finite element (FE) model (“Minefill-2D”) that can model these interactions, although only in a two-dimensional (plane–strain or axisymmetric) fashion. It is shown that arching significantly influences the total stress distribution in a typical stope during filling, but only if and when effective stress develops. For cemented backfill, arching sometimes does not fully mobilize the cement bond strength, so that assessment of arching using traditional limit equilibrium methods is often not appropriate.
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Eshun, S. N., Solomon Senyo Robert Gidigasu i S. K. Y. Gawu. "The Effect of Clay Pozzolana-Cement-Composite on the Strength Development of a Hydraulic Backfill". Ghana Mining Journal 18, nr 1 (28.06.2018): 32–38. http://dx.doi.org/10.4314/gm.v18i1.4.
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The study sought to investigate the potential application of clay pozzolana as a supplement for cement in hydraulic backfill, using classified tailings from AngloGold Ashanti, Obuasi Mine. The percentage of the Portland cement that could be substituted with the clay pozzolana to produce backfill with best strength was determined. 10%, 25%, 30%, 35% and 40% of the ordinary Portland cement were replaced with clay pozzolana and then mixed with tailings and water. The slurry produced was cast into cylindrical specimen of 50mm diameter by 120mm high and tested for compressive strength after curing for 7, 14, 21, 28 and 56 days. The results indicate that, clay pozzolana-cement composite has potential for application in hydraulic back fill production without increased risk to safety and dilution. It was noted that hydraulic backfill with 10%, 25%, 30% and 35% of the ordinary portland cement replaced with clay pozzolana had strengths greater than those obtained for ordinary portland cement alone. Ten percent (10%) pozzolana content gave the maximum strength followed by 25% pozzolana. It is recommended that for safety and economic considerations, the cement content should be replaced by 25% pozzolana in the production of backfills. Keywords: Hydraulic Backfill, Portland Cement, Clay Pozzolana, Unconfined Compressive Strength
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Li, Li, i Michel Aubertin. "A modified solution to assess the required strength of exposed backfill in mine stopes". Canadian Geotechnical Journal 49, nr 8 (sierpień 2012): 994–1002. http://dx.doi.org/10.1139/t2012-056.
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Backfilling contributes to the improvement of ground stability and reduction of ore dilution in underground mines. A critical issue for backfilled stope design is the required strength for the fill material. A practical solution to address this question was proposed by Mitchell and co-workers for stopes with an exposed face and a high aspect ratio (height H over width B). However, this solution is not directly applicable to stopes with a relatively low aspect ratio (H/B). Its application is also restricted by additional limitations on the strength along the fill–rock interfaces and the load applied on top of the backfill. In this note, the model proposed by Mitchell and co-workers is modified to provide an estimate of the required strength of backfill for various geometries, material properties, and surface loads. The modified Mitchell (MM) solution is validated against experimental results. Sample calculations with the MM solution are also presented and discussed.
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Helinski, Matthew, Martin Fahey i Andy Fourie. "Numerical Modeling of Cemented Mine Backfill Deposition". Journal of Geotechnical and Geoenvironmental Engineering 133, nr 10 (październik 2007): 1308–19. http://dx.doi.org/10.1061/(asce)1090-0241(2007)133:10(1308).
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Zhang, Hai Bo, i Ya Jie Chen. "Study on the Mechanism of Backfill and Surrounding Rock of Open Stope during Subsequent Backfill Mining". Advanced Materials Research 753-755 (sierpień 2013): 452–56. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.452.
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In order to analyze the mechanism of backfill and surrounding rock of open stope during subsequent backfill mining, take M1 ore body mining in a mine as engineering background, and simulate the mechanism of surrounding rock and backfill by using FLAC3D numerical software. Results show that the backfill can effectively alleviate or transfer the stress concentration state of the room floor and pillar, apparently restrain the displacement of the cavity plate and pillar, and improve the plasticity distribution range in a limited degree.
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Cheng, Qiangqiang, Yaben Guo, Chaowei Dong, Jianfei Xu, Wanan Lai i Bin Du. "Mechanical Properties of Clay Based Cemented Paste Backfill for Coal Recovery from Deep Mines". Energies 14, nr 18 (13.09.2021): 5764. http://dx.doi.org/10.3390/en14185764.
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Fly ash cement is used to solidify marine clay to prepare marine-clay-based cemented paste backfill (MCCPB) to fill the underground goaf of mines, which not only utilizes solid waste such as fly ash and marine clay, but also controls surface subsidence and protects the environment. To simulate the complex underground mine water environment of the filling body, a dry-wet cycle aquatic environment test under different material ratios and curing ages was designed. The water absorption and unconfined compression strength (UCS) of MCCPB with curing ages of 7 and 28 days under the action of 0, 1, 3, and 7 dry-wet cycles were investigated. The results indicate as the number of dry-wet cycles increases, the surface of MCCPB becomes significantly rougher, and the water content and the solid mass decrease accordingly. Different ratios and curing ages of MCCPB in dry-wet cycles of the UCS tend first to increase, then decrease. Meanwhile, the stress-strain curve of the specimen shows that the trend in the elastic modulus is consistent with that of UCS (first increasing, then decreasing), and that, the minimum UCS value of the specimen still meets the early strength requirements of cemented paste backfill in coal mine geothermal utilization. On the one hand, it proves the feasibility of fly ash cement-solidified marine clay for use as cemented paste backfill in coal mines; on the other hand, it also expands the available range of cemented paste backfill materials in coal mines.
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Chen, Shao Jie, Wei Jia Guo, Hai Long Wang i Yi Tao Zhong. "Study on the Mechanical Properties of Backfill Cream-Body during Coal Mining". Applied Mechanics and Materials 170-173 (maj 2012): 533–36. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.533.
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In order to research the mechanical properties of the backfill cream-body under engineering conditions in the coal mine, the uniaxial compression test of backfill cream-body with different ages abtained from the filling locale of Daizhuang coal mine is conducted with MTS815.03 rock test system. The characteristics of backfill cream-body in the limited space and a certain environment are studied. Research shows that, the strength of backfill cream-body is high, but coagulability is bad and the discreteness of mechanical properties is different; Uniaxial compressive strength is 2.3 ~ 13.17 MPa and the average is 5.436 MPa; The elastic modulus is very low ,which is only 53.66 ~ 2614.35 MPa and the average is 645.14 MPa. The deformation is bigger when absorbing load; Poisson's ratio is low, which is only 0.0001 ~ 0.2112 and the average is 0.0265, which indicates that the backfill cream-body doesn't need the space of transverse deformation when bearing compression deformation; The mechanical parameters of backfill cream-body with different ages are fitted and regressed. Test results is important to control surface mining subsidence effectively, liberate the coal resources under buildings, railways and waterbodies and protect the ecological environment.
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Zhou, Nan, Meng Li, Jixiong Zhang i Rui Gao. "Roadway backfill method to prevent geohazards induced by room and pillar mining: a case study in Changxing coal mine, China". Natural Hazards and Earth System Sciences 16, nr 12 (29.11.2016): 2473–84. http://dx.doi.org/10.5194/nhess-16-2473-2016.
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Abstract. Coal mines in the western areas of China experience low mining rates and induce many geohazards when using the room and pillar mining method. In this research, we proposed a roadway backfill method during longwall mining to target these problems. We tested the mechanical properties of the backfill materials to determine a reasonable ratio of backfill materials for the driving roadway during longwall mining. We also introduced the roadway layout and the backfill mining technique required for this method. Based on the effects of the abutment stress from a single roadway driving task, we designed the distance between roadways and a driving and filling sequence for multiple-roadway driving. By doing so, we found the movement characteristics of the strata with quadratic stabilization for backfill mining during roadway driving. Based on this research, the driving and filling sequence of the 3101 working face in Changxing coal mine was optimized to avoid the superimposed influence of mining-induced stress. According to the analysis of the surface monitoring data, the accumulated maximum subsidence is 15 mm and the maximum horizontal deformation is 0.8 mm m−1, which indicated that the ground basically had no obvious deformation after the implementation of the roadway backfill method at 3101 working face.
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Xu, Ying, Jian Biao Bai, Yong Chen i Jun Yue. "Development of Scientific Mining: a Case Study of Gob-Side Entry Retaining Technology in China". Advanced Materials Research 255-260 (maj 2011): 3786–92. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.3786.
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The gob-side entry retaining technology, one of the scientific mining technical system, can enhance coal recovery rate and reduce entry excavation quantity. However, only the effective entry-side support and the proper entry-in support could guarantee stability of the retaining entry undergoing mining influences of two working faces. In order to recover the section coal pillar between two working faces, the technology is applied in Qinxin coal mine. By using the high-water rapid hardening material as backfill material, the backfill pumps as transportation equipments of the material, the steel formwork and backfill bag as forming molds of the material, the entry-side support is of high support resistance, certain shrinkage, convenient construction. As for the entry-in support, the bolt support is designed to improve the bearing capacity and anti-deformation capacity of the surrounding rock, and the single hydraulic prop is adopted to reinforce roof support. The observation results show that the retaining entry keeps good performance. The case not only brings better economical benefit for Qinxin coal mine but also has referential significance for other coal mines.
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Deng, Hongwei, Yao Liu, Weiyou Zhang, Songtao Yu i Guanglin Tian. "Study on the Strength Evolution Characteristics of Cemented Tailings Backfill from the Perspective of Porosity". Minerals 11, nr 1 (15.01.2021): 82. http://dx.doi.org/10.3390/min11010082.
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At present, the filling mining method is widely used. To study strength evolution laws of cemented tailings backfill (CTB) under different curing ages, in the experiment, mine tailings were used as aggregates, ordinary Portland cement (PC32.5) was used as cementing materials, and different additives (lime and fly ash) were added to make filling samples with the solids mass concentration at 74% and the cement-sand ratios 1:4, 1:6 and 1:8. Based on the nuclear magnetic resonance (NMR) technology, the porosity test of filling samples with curing ages of 3 d, 7 d and 28 d was carried out, and the uniaxial compressive strength test was carried out on the servo universal material testing machine. The relationship between the uniaxial compressive strength and porosity of backfills and the curing age in the three groups was studied, and change laws of the porosity variation and strength growth rate of backfills were analyzed. Based on the variation in porosity, the strength evolution model of the CTB under different curing ages was established, and the model was fitted and verified with test data. Results show that the uniaxial compressive strength, porosity, porosity variation, and strength growth rate of the three groups of backfills gradually increase with the increase of the curing age, the porosity of backfill basically increases with the decrease of the cement–sand ratio, and the porosity of backfill decreases with the increase of the curing age. Porosity variations and relative strength values of the three groups of backfills under different cement-sand ratios obey an exponential function, and the two have a good correlation, indicating that the established filling strength evolution model can well reflect strength evolution laws of the CTB with the change of curing age.
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Cao, Zhiwei, Bing Liu, Xibing Li, Diyuan Li i Longjun Dong. "Experimental Study on Backfilling Mine Goafs with Chemical Waste Phosphogypsum". Geofluids 2019 (16.01.2019): 1–12. http://dx.doi.org/10.1155/2019/9218916.
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To explore the feasibility of cemented paste backfill with phosphogypsum (PG), bleeding water and rheological tests (slump and on-site pipeline loop tests) were performed with PG backfill slurry (PGBS). In the bleeding water test, the PGBS concentration with minimal bleeding water was measured between 60.87 and 67.61%; in the rheological slump test, values of 61 to 68% were determined for the on-site pipeline loop test. The rheological pipeline loop test demonstrated that the resistance coefficient is lowest when the concentration is no higher than 65%. Through industrial experiments, PG slurry with a concentration of 64%–65% backfill was successfully applied to the goaf. The experimental results demonstrate that PGBS with characteristics of “less bleeding water” and “improved pumpability” is obtained when its concentration is between 61 and 65%. Paste-like PG slurry was proven to be optimal for cemented PG backfilling technology.
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Béket Dalcé, Jean, Li Li i Pengyu Yang. "Experimental Study of Uniaxial Compressive Strength (UCS) Distribution of Hydraulic Backfill Associated with Segregation". Minerals 9, nr 3 (28.02.2019): 147. http://dx.doi.org/10.3390/min9030147.
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Stope backfilling with mine wastes has become a common practice in underground mines worldwide. Despite the increasing popularity in paste and rock fills, hydraulic fill made of classified mill tailings or sands remains commonly used in many mines. When such a slurried material is placed in a mine stope, a phenomenon known as segregation can take place associated with the quick drainage and consolidation of the hydraulic fill, thereby leading to a heterogeneous fill mass. While numerous publications have focused on the alleviation of segregation, there are few studies on the characterization of the distribution of geotechnical properties within hydraulic fill due to segregation. It is particularly scarce to quantify the spatial variation of the segregation and the resulting geotechnical properties after a backfill is placed in an opening. There is also a gap to quantitatively describe the degree of segregation using an appropriate expression or definition. The aim of this study is to investigate the effect of the segregation on the spatial variation of the geotechnical properties of hydraulic fill. Laboratory tests were performed with the cemented hydraulic backfill prepared with columns of different heights. The experimental results indicate that the segregation takes place and the resulting physical and mechanical properties can vary throughout the columns for samples higher than twice of the standard size. These results also indicate that the mechanical properties of a hydraulic fill obtained in a laboratory following the current practice with standard samples may not be representative of the fill mass placed in mine stopes. Expressions are proposed to quantify the degree of segregation associated with the spatial variation of particle sizes of mine hydraulic backfill.
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Dong, Yu, Yang Wu, Lei Chang Shao i Zhong Jie Duan. "Numerical Simulation Analysis of Coal Mining with Paste-like Backfill under Water Based on UDEC". Advanced Materials Research 962-965 (czerwiec 2014): 935–38. http://dx.doi.org/10.4028/www.scientific.net/amr.962-965.935.
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Based on the instance of extremely thick coal seam mining under aquifer in Gonggeyingzi Coal Mine, the theoretical calculation for the height of water flowing fracture zone in this coal mine was 30.6m and calculation model was established. Analyzed by the UDEC software, the surface displacement of backfill mining was 1532mm and the height of overburden rock plastic zone was 36.5m. Compared with 135m away from coal roof to aquifer, slicing backfill mining under aquifer was confirmed to be safe and feasible based on the theoretical calculation and analysis of UDEC. The results provided the basis for the safety of extremely thick coal seam mining under aquifer in this coal mine.
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Zhao, Kang, Qiang Li, Yajing Yan, Keping Zhou, Shuijie Gu i Shengtang Zhu. "Numerical Calculation Analysis of the Structural Stability of Cemented Fill under Different Cement-Sand Ratios and Concentration Conditions". Advances in Civil Engineering 2018 (27.08.2018): 1–9. http://dx.doi.org/10.1155/2018/1260787.
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The effect of lime-sand ratio and slurry concentration on the mechanical properties of backfills is important. To achieve green and high-efficiency mining, accurately determining the optimum ratio of cemented tailings for certain tungsten tailings and ensuring the safety and stability of the mine stope structure are important. The cement-sand ratios used in this research were 1 : 6 and 1 : 8. The mechanical properties were evaluated by using 68%, 72%, and 78% of tailing cemented filling materials. The corresponding physical and mechanical parameters were obtained through uniaxial compression, splitting, and shearing mechanical experiments on the backfill specimens. FLAC3D was used to investigate the mechanical properties of cement-filled pillars and the stability of supporting surrounding rocks on the basis of the mine’s current room pillar structure size parameters and mining sequence. The key factors that affect the stability of the goaf were analyzed by evaluating the plastic zone area of the stope, maximum and minimum principal stresses, and displacement change. The structural characteristics of stope structures and changes of rock mass damage were obtained under different cement-tailing ratios and concentrations. A cemented backfill with a cement-tailing ratio of 1 : 8 and a concentration of 68% was selected as the best solution for the mine in terms of safety and economic considerations.
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Zhang, Qinli, Bingyi Zhang, Qiusong Chen, Daolin Wang i Xiang Gao. "Safety Analysis of Synergetic Operation of Backfilling the Open Pit Using Tailings and Excavating the Ore Deposit Underground". Minerals 11, nr 8 (28.07.2021): 818. http://dx.doi.org/10.3390/min11080818.
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The transition from open pit mining to underground mining is essential for mineral resources to achieve deep excavation. Recently, cemented paste backfill (CPB) has been proposed as a novel technology to achieve open pit backfill (OPB). The proposed method not only eliminates the danger of the open-pit slope but also reduces the disposal of waste tailings. In order to ensure safe mining during the synergetic operation of OPB and underground mining, it is of great significance to improve this technology. In the present study, an open-pit metal mine in Anhui Province was taken as the research object. Then, the safety of underground stope roofs, underground backfill pillars, and open-pit slopes was evaluated during OPB. To this end, numerical simulations were performed and experiments were conducted on a similar physical model. Accordingly, the backfill mechanical parameters were optimized. The obtained results show that backfill height exerts the most significant effect on the safety of roofs and underground backfill pillars, accompanied by small displacements along the vertical direction during the backfill process. Moreover, concentration was observed at the foot of the slope, while the overall structure remained stable with no considerable displacement. The overall safety factors met the safety requirements. Based on the obtained results, the optimal foundation strength, foundation height, backfill strength and backfill height were 4 MPa, 10 m, 1.5 MPa, and 120 m, respectively. Moreover, it was concluded that displacements in the abovementioned three regions tend to be stable when the backfill height exceeds 150 m without damage. The present article provides a certain theoretical and application guideline for OPB practices in similar metal mines and suggests possibilities for cleaner production.
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Fan, Zuo Peng, Zhong Hui Zhang, Qian He, Meng Qian Cai i Chen Shi. "Effects of Naphthalene-Based Super Plasticizer on the Performances of Whole Tailings Backfill Materials". Applied Mechanics and Materials 608-609 (październik 2014): 962–65. http://dx.doi.org/10.4028/www.scientific.net/amm.608-609.962.
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According to existing backfill process of the Jiaojia Gold Mine, this research uses the whole tailings as fill aggregate to replacement grade tailings. The solid concentration of backfill slurry was increased from 68% to 72% and the naphthalene-based superplasticizer was used to achieve gravity well-distributed transport. The effects of naphthalene-based superplasticizer on the sedimentation rate, bleeding rates, fluidity and compressive strength of the whole tailings backfill materials were investigated with different content. The results show that naphthalene-based superplasticizer can slow the sedimentation rate, improve the fluidity of whole tailings backfill slurry and increase the compressive strength. The fluidity of the whole tailings backfill slurry with 0.3% naphthalene superplasticizer is largest and the compressive strength is highest in all of the specimens.