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Classification and instability mechanism of anchored "beam-arch" composite structure in rock burst roadways with top-coal

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Meitan Xuebao/Journal of the china Coal Society 2024年第4期49卷 1752-1770页

作者： Cao, Anye Guo, Wenhao Wen, Yingyuan Wang, Songwei Liu, Yaoqi Hao, Qi Lü, Guowei Li, Geng School of Mines China University of Mining & Technology Xuzhou 221116 China School of Geology and mining Engineering Xinjiang University Urumqi 830046 China Jiangsu Engineering Laboratory of Mine Earthquake Monitoring and Prevention China University of Mining & Technology Xuzhou 221116 China

The rock burst frequently occurs in the roadways with top coal, and the roof disasters are particularly severe under dynamic stress in china. In order to explore the classification and instability mechanisms of anchoring structures in the roadways with top-coal, analog simulation experiments, theoretical analysis, and data statistics were used under the engineering background of the large-area rock burst roof failure in the Working Face 301 of a mine in Shaanxi Province, china. The dynamic load response characteristics of the stress, displacement, and surface acceleration of the surrounding rock in the roadways with top coal were analyzed. The classification characteristics of the roof anchoring structure under the influence of top coal thickness and cables were studied. The stress response mechanism of the roadways with top coal under elastic waves was explored, and the instability mechanism of the anchoring "beam arch" structure was proposed. The rock burst resistance of the air-return roadway in the Working Face 301 was evaluated, and the corresponding optimization schemes for the "beam-arch" composite structure were proposed. The results show that ① the monitoring data of stress and displacement of the surrounding rock in the roadways with top coal under dynamic stress verify the existence of internal and external beam or arch anchoring structures in the roof. Due to the increase in the thickness of top coal, there is a transition from "beam" to "arch" in the anchoring structure of the inner layer of the roof; ② based on the relative relationship between the thickness of the top coal and the cables, the roof anchoring structure is divided into "superimposed-beam and arch" for thin top coal, "composite-beam and arch" for thick top coal, and "combined arch" for extra thick top coal. A critical thickness index for the transformation of thick coal beams from "beam" to "arch" is established; ③ the instability mechanism of the beam structure and the arch structure is that they fail after reaching their tensile and

关键词： Arches

Evaluation of frictional pressure drop correlations for air-water and air-oil two-phase flow in pipeline-riser system

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Petroleum Science 2024年第2期21卷 1305-1319页

作者： Nai-Liang Li Bin Chen School of Low-carbon Energy and Power Engineering China University of Mining and TechnologyXuzhou221116JiangsuChina State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049ShaanxiChina

Accurate prediction of the frictional pressure drop is important for the design and operation of subsea oil and gas transporting system considering the length of the pipeline. The applicability of the correlations to pipeline-riser flow needs evaluation since the flow condition in pipeline-riser is quite different from the original data where they were derived from. In the present study, a comprehensive evaluation of 24prevailing correlation in predicting frictional pressure drop is carried out based on experimentally measured data of air-water and air-oil two-phase flows in pipeline-riser. Experiments are performed in a system having different configuration of pipeline-riser with the inclination of the downcomer varied from-2°to-5°to investigated the effect of the elbow on the frictional pressure drop in the riser. The inlet gas velocity ranges from 0.03 to 6.2 m/s, and liquid velocity varies from 0.02 to 1.3 m/s. A total of885 experimental data points including 782 on air-water flows and 103 on air-oil flows are obtained and used to access the prediction ability of the correlations. Comparison of the predicted results with the measured data indicate that a majority of the investigated correlations under-predict the pressure drop on severe slugging. The result of this study highlights the requirement of new method considering the effect of pipe layout on the frictional pressure drop.

关键词： Frictional pressure drop Pipeline-riser Gas-liquid two-phase flow Severe slugging Correlation

Mechanical behavior and failure mechanisms of rock bolts subjected to static-dynamic loads

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International Journal of mining Science and technology 2024年第3期34卷 281-288页

作者： Hongpu Kang Guiyang Yuan Linpo Si Fuqiang Gao Jinfu Lou Jinghe Yang Shuangyong Dong CCTEG Coal Mining Research InstituteBeijing 100013China State Key Laboratory of Intelligent Coal mining and Strata Control Beijing 100013China

This study explores the effects of dynamic and static loading on rock bolt performance a key factor in maintaining the structural safety of coal mine roadways susceptible to coal bursts.Employing a housemade load frame to simulate various failure scenarios,pretension-impact-pull tests on rock bolts were conducted to scrutinize their dynamic responses under varied static load conditions and their failure traits under combined loads.The experimental results denote that with increased impact energy,maximum and average impact loads on rock bolts escalate significantly under pretension,initiating plastic deformation beyond a certain threshold.Despite minor reductions in the yield load due to impactinduced damage,pretension aids in constraining post-impact deformation rate and fluctuation degree of rock bolts.Moreover,impact-induced plastic deformation causes internal microstructure dislocation,fortifying the stiffness of the rock bolt support system.The magnitude of this fortification is directly related to the plastic deformation induced by the impact.These findings provide crucial guidance for designing rock bolt support in coal mine roadway excavation,emphasizing the necessity to consider both static and dynamic loads for improved safety and efficiency.

关键词： Rock bolt Pretension Static and dynamic load Impact

Sub-Homogeneous Peridynamic Model for Fracture and Failure Analysis of Roadway Surrounding Rock

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 3167-3187页

作者： Shijun Zhao Qing Zhang Yusong Miao Weizhao Zhang Xinbo Zhao Wei Xu School of Science Qingdao University of TechnologyQingdao266520China College of Mechanics and Materials Hohai UniversityNanjing211100China Xibei mining Co. Ltd.Shandong Energy GroupXi’an710018China

The surrounding rock of roadways exhibits intricate characteristics of discontinuity and heterogeneity.To address these complexities,this study employs non-local Peridynamics(PD)theory and reconstructs the kernel function to represent accurately the spatial decline of long-range force.Additionally,modifications to the traditional bondbased PD model are made.By considering the micro-structure of coal-rock materials within a uniform discrete model,heterogeneity characterized by bond random pre-breaking is introduced.This approach facilitates the proposal of a novel model capable of handling the random distribution characteristics of material heterogeneity,rendering the PD model suitable for analyzing the deformation and failure of heterogeneous layered coal-rock mass structures.The established numerical model and simulation method,termed the sub-homogeneous PD model,not only incorporates the support effect but also captures accurately the random heterogeneous micro-structure of roadway surrounding rock.The simulation results obtained using this model show good agreement with field measurements from the Fucun coal mine,effectively validating the model’s capability in accurately reproducing the deformation and failure mode of surrounding rock under bolt-supported(anchor cable).The proposed subhomogeneous PD model presents a valuable and effective simulation tool for studying the deformation and failure of roadway surrounding rock in coal mines,offering new insights and potential advancements.

关键词： Roadway surrounding rock peridynamics heterogeneous material fracture analysis numerical simulation

Velocity analysis of supersonic jet flow in double-cone ignition scheme

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Chinese Physics B 2024年第6期33卷 460-465页

作者：朱仲源张成龙李英骏 School of Science China University of Mining and TechnologyBeijing 100083China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyBeijing 100083China Double-cone ignition(DCI)joint team State Key Laboratory for Geomechanics and Deep Underground EngineeringChina University of Mining and TechnologyBeijing 100083China

In the double-cone ignition schemes(DCIS), the deuterium–tritium target shell is ablated and compressed by a highpower nanosecond laser in Au-cones to generate plasmas. Under the actions of spherically symmetric compression and acceleration along the Au cone, they will be ejected out of the cone mouth and collide with each other. The plasmas experience conversion from kinetic energy to internal energy at the vertex of the geometric center of two Au cones that are symmetric to each other, because of which high-density fusion plasmas are preheated. This key physical process has undergone experimental verification on the Shenguang-II upgraded facility in china. Apparently, the improvement and optimization of the velocity of plasmas in hypersonic jet flow at the cone mouth are crucial for the success of the DCIS. In the DCIR7 experiment of the Shenguang-II upgraded facility, a velocity yield of approximately 130–260 km/s was achieved for the plasmas at the cone mouth, with a result of nearly 300 km/s based on numerical simulation. In this paper, theoretical analysis is performed as regards the process, in which target shells are ablated and compressed by laser to generate highvelocity plasmas ejected through jet flow. Based on this analysis, the formula for the velocity of plasmas in supersonic jet flow at the cone mouth is proposed. This study also provides measures that are more effective for improving the kinetic energy of plasmas and optimizing energy conversion efficiency, which can serve as theoretical references for the adjustment and optimization of processes in subsequent experiments.

关键词： double-cone ignition(DCI) plasma hydrodynamics laser fusion

Entropy consistency-based adaptive sampling method for determining the scale effect in the joint roughness coefficient

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Journal of Earth Science 2024年

作者： Jibo Qin Jun Ye Xiaoming Sun Shigui Du State Key Laboratory for Tunnel Engineering china university of mining and technology-Beijing School of Mechanics and Civil Engineering china university of mining and technology-Beijing Institute of Rock Mechanics Ningbo university

The joint roughness coefficient （JRC） is one of the key parameters for evaluating the shear strength of rock joints. Because of the scale effect in the JRC， reliable JRC values are of great importance for most rock engineering projects. During the collection process of JRC samples， the redundancy or insufficiency of representative rock joint surface topography （RJST） information in serial length JRC samples is the essential reason that affects the reliability of the scale effect results. Therefore， this paper proposes an adaptive sampling method， in which we use the entropy consistency measure Q（a） to evaluate the consistency of the joint morphology information contained in adjacent JRC samples. Then the sampling interval is automatically adjusted according to the threshold Q(at) of the entropy consistency measure to ensure that the degree of change of RJST information between JRC samples is the same， and ultimately makes the representative RJST information in the collected JRC samples more balanced. The application results of actual cases show that the proposed method can obtain the scale effect in the JRC efficiently and reliably.

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Wetting front migration model of ion-adsorption rare earth during the multi-hole unsaturated liquid injection

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 483-496页

作者： Yu Wang Xiaojun Wang Yuchen Qiu Hao Wang Gang Li Kaijian Hu Wen Zhong Zhongqun Guo Bing Li Chunlei Zhang Guangxiang Ye Jiangxi Key Laboratory of mining Engineering Jiangxi University of Science and TechnologyGanzhou341000China School of Resources and Environment Engineering Jiangxi University of Science and TechnologyGanzhou341000China School of Civil Engineering and Surveying&Mapping Engineering Jiangxi University of Science and TechnologyGanzhou341000China Ganzhou Nonferrous Metallurgy Research Institute Ganzhou341000China

In the process of ion-adsorption rare earth ore leaching,the migration characteristics of the wetting front in multi-hole injection holes and the influence of wetting front intersection effect on the migration distance of wetting fronts are still unclear.Besides,wetting front migration distance and leaching time are usually required to optimize the leaching process.In this study,wetting front migration tests of ionadsorption rare earth ores during the multi-hole fluid injection(the spacing between injection holes was 10 cm,12 cm and 14 cm)and single-hole fluid injection were completed under the constant water head height.At the pre-intersection stage,the wetting front migration laws of ion-adsorption rare earth ores during the multi-hole fluid injection and single-hole fluid injection were identical.At the postintersection stage,the intersection accelerated the wetting front migration.By using the Darcy’s law,the intersection effect of wetting fronts during the multi-hole liquid injection was transformed into the water head height directly above the intersection.Finally,based on the Green-Ampt model,a wetting front migration model of ion-adsorption rare earth ores during the multi-hole unsaturated liquid injection was established.Error analysis results showed that the proposed model can accurately simulate the infiltration process under experimental conditions.The research results enrich the infiltration law and theory of ion-adsorption rare earth ores during the multi-hole liquid injection,and this study provides a scientific basis for optimizing the liquid injection well pattern parameters of ion-adsorption rare earth in situ leaching in the future.

关键词： Ion-adsorption rare earth ore Multi-hole unsaturated liquid injection In situ leaching Intersection effect Calculation model

Enhancement of heavy metals desorption from the soil by eddy deep leaching in hydrocyclone

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Journal of Environmental Sciences 2024年第1期135卷 242-251页

作者： Ning Wang Hao Lu Bo Liu Tai Xiong Jianping Li Hualin Wang Qiang Yang School of Mechanical and Power Engineering East China University of Science and TechnologyShanghai 200237China National Engineering Laboratory for High Concentration Refractory Organic Wastewater Treatment technology East China University of Science and TechnologyShanghai 200237China

An eddy deep leaching technology was developed in this paper to address the challenge of treating heavy metal contaminants in industrial mining areas.The desorption effect of As,Cd,Sb and Pb was investigated utilizing chemical leaching and physical eddy techniques.It was found that the heavy metals concentration increased with decreasing particle size.The highest proportion of Cd in the form distribution of soil was in the bound to iron and manganese oxides,while the maximum proportion of As,Sb and Pb were in the residual.The optimal solid-liquid ratio of the hydrocyclone was 1:20,and the corresponding separation efficiency and flow rate were 84.7%and 1.76 m^(3)/hr,respectively.The grade efficiency of soil particle separation increases with particle size and exceeds 99%for particles above 1,000μm.Leaching experiments have revealed that oxalic acid(OA)and a combination of oxalic acid and EDTA(OAPE)were more efficient than citric acid(CA)and a combination of citric acid and EDTA(CAPE)for the desorption of heavy metals,respectively.The comparison of OAPE and eddy leaching found that the latter improved the desorption efficiency by 9.4%,7.5%,7.2%and 7.8%for As,Cd,Sb and Pb compared to the former,respectively.The results demonstrated that the eddy leaching technique could further enhance the desorption efficiency of heavy metals.It is expected to provide technical support for soil remediation with reduced usage of leaching agents.

关键词： Heavy metals Soil remediation Oxalic acid Eddy leaching Hydrocyclone

Determining Sets and Determining Numbers of Finite Groups

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Algebra Colloquium 2024年第1期31卷 111-128页

作者： Dengyin Wang Chi Zhang Haipeng Qu School of Mathematics China University of Mining and Technology XuzhouJiangsu 221116China School of Mathematics and Computer Science Shanxi Normal University LinfenShanxi 041000China

A subset D of a group G is a determining set of G if every automorphism of G is uniquely determined by its action on D,and the determining number of G,a(G),is the cardinality of a smallest determining set.A group G is called a DEG-group if α(G)equals(G),the generating number of G.Our main results are as follows.Finite groups with determining number 0 or 1 are classified;finite simple groups and finite nilpotent groups are proved to be DEG-groups;for a given finite group H,there is a DEG-group G such that H is isomorphic to a normal subgroup of G and there is an injective mapping from the set of all finite groups to the set of finite DEG-groups;for any integer k≥2,there exists a group G such that α(G)=2 and(G)≥k.

关键词： determining number automorphisms nilpotent groups