Simulation study of top coal caving and conveying process based on smoothed particle hydrodynamics
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摘要: 目前针对综放开采中顶煤放出规律的数值模拟研究中,对于顶煤运动的连续−非连续性问题需复杂的耦合算法,必须解决煤岩界面信息精确交互问题,且忽略了刮板输送机输送过程。针对该问题,基于光滑粒子动力学构建了无网格数值计算模型,通过建立连续介质力学控制方程的光滑粒子动力学离散方程,并引入弹塑性土体本构模型和Drucker−Prager屈服准则,实现了顶煤坍塌、运移、放出过程的动态模拟。考虑采场实际放煤和输煤过程,构建了刮板输送机模型,模拟沿工作面水平方向顶煤放出和底煤输送过程,得到不同刮板输送机运行速度(0~1.5 m/s)下的煤岩界面和煤流速度变化规律。仿真结果表明:弹塑性土体本构模型可有效模拟颗粒的流动行为,通过设定摩擦角、弹性模量等材料参数,避免了传统离散元法模型的参数不定问题;煤流速度稳定后,放煤口附近的顶煤应力分布呈 “双峰”形态;刮板输送机运行速度对放煤时间影响较大,但对终止的煤岩界面和放出体形状影响较小;多支架同时放煤需考虑刮板输送机的输送能力,不同支架之间的底煤输送干涉可能导致放煤口的堵塞效应; “见矸关门”准则导致不同放煤口放煤量存在差异,40个放煤口顶煤放出量的标准差(7.52 m2)高于自动放煤的标准差(1.93 m2)。Abstract: Currently, in the numerical simulation research on the release laws of top coal during fully mechanized mining, complex coupling algorithms are required to address the continuity-discontinuity issues of top coal movement and ensure precise interaction of coal-rock interface information. However, the conveying process of scraper conveyors is typically neglected in these simulations. To address this problem, a meshless numerical computation model was constructed based on smoothed particle hydrodynamics (SPH). The discrete equations of SPH, derived from the control equations of continuous medium mechanics, were established. An elastic-plastic soil constitutive model along with the Drucker-Prager yield criterion were introduced to achieve dynamic simulation of the caving, movement, and release processes of the top coal. Considering the actual coal release and conveying processes in the mining area, a scraper conveyor model was constructed to simulate the release of top coal and the conveying of bottom coal along the working face, obtaining the variations in coal-rock interface and coal flow velocity at different scraper conveyor operating speeds (0-1.5 m/s). The simulation results indicated that the elastic-plastic soil constitutive model effectively simulated the flow behavior of particles. By setting parameters such as friction angle and elastic modulus, the issue of uncertain parameters commonly found in traditional discrete element models was avoided. After stabilization of the coal flow velocity, the stress distribution of the top coal near the coal drawing outlet exhibited a "double peak" pattern. The operating speed of the scraper conveyor significantly impacted the coal drawing time, while its effect on the coal-rock interface at termination and the shape of the released body was minimal. When multiple supports released coal simultaneously, the conveying capacity of the scraper conveyor needed to be considered, as interference in bottom coal transportation between different supports could lead to blockage effects at the release port. The "gangue closing" rule resulted in variations in the amount of coal drawing at different coal drawing outlets, with the standard deviation of top coal drawing amount from 40 coal drawing outlets (7.52 m²) being greater than that of automatic coal drawing (1.93 m²).
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表 1 SPH模型参数设定
Table 1. Parameters seting in SPH model
参数 取值 参数 取值 初始粒子间距
$ {d}_{{\mathrm{ini}}} $/m取决于具体算例 声速$ {s} $/(m·s−1) $ \mathrm{ }s=\sqrt{\dfrac{K}{\rho}} $ 光滑长度$ {h}_{i} $/m $ h_i=1.2d_{\mathrm{ini}} $ 人工黏性力系数
$ {\mathrm{\alpha }}_{\mathrm{\Pi }},\;{\mathrm{\beta }}_{\mathrm{\Pi }} $$ {\mathrm{\alpha }}_{\mathrm{\Pi }}=0.1,{\mathrm{\beta }}_{\mathrm{\Pi }}=0.1 $ 时间步长$ \Delta t $/s $ \Delta t\leqslant C_{\mathrm{cour}}\left(\dfrac{h_i}{s}\right) $ 表 2 铝颗粒崩塌模拟采用的材料参数
Table 2. Material parameters used for aluminum particle collapse simulations
参数 数值 参数 数值 密度$ \rho $/(kg·m3) 2 004.0 弹性模量$ E $/MPa 5.84 摩擦角$ \phi $/(°) 21.9 泊松比$ \upsilon $ 0.3 黏聚力$ C $/Pa 0 -
[1] YANG Shengli,ZHANG Jinwang,CHEN Yi,et al. Effect of upward angle on the drawing mechanism in longwall top-coal caving mining[J]. International Journal of Rock Mechanics and Mining Sciences,2016,85:92-101. doi: 10.1016/j.ijrmms.2016.03.004 [2] 王家臣. 我国放顶煤开采的工程实践与理论进展[J]. 煤炭学报,2018,43(1):43-51.WANG Jiachen. Engineering practice and theoretical progress of top-coal caving mining technology in China[J]. Journal of China Coal Society,2018,43(1):43-51. [3] 王国法,庞义辉,马英. 特厚煤层大采高综放自动化开采技术与装备[J]. 煤炭工程,2018,50(1):1-6.WANG Guofa,PANG Yihui,MA Ying. Automated mining technology and equipment for fully-mechanized caving mining with large mining height in extra-thick coal seam[J]. Coal Engineering,2018,50(1):1-6. [4] 王国法,范京道,徐亚军,等. 煤炭智能化开采关键技术创新进展与展望[J]. 工矿自动化,2018,44(2):5-12.WANG Guofa,FAN Jingdao,XU Yajun,et al. Innovation progress and prospect on key technologies of intelligent coal mining[J]. Industry and Mine Automation,2018,44(2):5-12. [5] 王家臣,富强. 低位综放开采顶煤放出的散体介质流理论与应用[J]. 煤炭学报,2002,27(4):337-341. doi: 10.3321/j.issn:0253-9993.2002.04.001WANG Jiachen,FU Qiang. The loose medium flow field theory and its application on the longwall top-coal caving[J]. Journal of China Coal Society,2002,27(4):337-341. doi: 10.3321/j.issn:0253-9993.2002.04.001 [6] 王家臣,杨建立,刘颢颢,等. 顶煤放出散体介质流理论的现场观测研究[J]. 煤炭学报,2010,35(3):353-356.WANG Jiachen,YANG Jianli,LIU haohao,et al. The practical observation research on loose medium flow field theory on the top-coal caving[J]. Journal of China Coal Society,2010,35(3):353-356. [7] 许永祥,王国法,李明忠,等. 特厚坚硬煤层超大采高综放开采支架−围岩结构耦合关系[J]. 煤炭学报,2019,44(6):1666-1678.XU Yongxiang,WANG Guofa,LI Mingzhong,et al. Structure coupling between hydraulic roof support and surrounding rock in extra-thick and hard coal seam with super large cutting height and longwall top coal caving operation[J]. Journal of China Coal Society,2019,44(6):1666-1678. [8] 张宁波,刘长友,陈玉明. 不稳定厚煤层放顶煤开采煤矸流场规律的数值模拟研究[J]. 煤炭技术,2014,33(12):1-4.ZHANG Ningbo,LIU Changyou,CHEN Yuming. Study on coal and gangue flow rule of top-coal caving with erratic hick coal seam by PFC2D[J]. Coal Technology,2014,33(12):1-4. [9] 王家臣,张锦旺,杨胜利,等. 多夹矸近水平煤层综放开采顶煤三维放出规律[J]. 煤炭学报,2015,40(5):979-987.WANG Jiachen,ZHANG Jinwang,YANG Shengli,et al. 3-D movement law of top-coal in near horizontal coal seam with multi-gangue under caving mining technique[J]. Journal of China Coal Society,2015,40(5):979-987. [10] 孙强,单成方,李亚锋,等. 浅埋双硬特厚煤层放煤规律分析及参数研究[J]. 工矿自动化,2022,48(2):61-69.SUN Qiang,SHAN Chengfang,LI Yafeng,et al. Analysis of coal drawing law and parameter research in shallow buried double hard and extra-thick coal seam[J]. Industry and Mine Automation,2022,48(2):61-69. [11] 何欣,刘长友,吴锋锋,等. 仰斜综放开采煤层仰角对顶煤放出规律的影响研究[J]. 煤炭科学技术,2021,49(9):25-31.HE Xin,LIU Changyou,WU Fengfeng,et al. Effect of elevation angle of coal seam on top-coal caving law in fully-mechanized top-coal caving mining face during topple mining[J]. Coal Science and Technology,2021,49(9):25-31. [12] 张锦旺,王家臣,魏炜杰. 工作面倾角对综放开采散体顶煤放出规律的影响[J]. 中国矿业大学学报,2018,47(4):805-814.ZHANG Jinwang,WANG Jiachen,WEI Weijie. Effect of face dip angle on the drawing mechanism in longwall top-coal caving mining[J]. Journal of China University of Mining & Technology,2018,47(4):805-814. [13] 冯宇峰. 综放开采含硬夹矸顶煤破碎机理及控制技术研究[J]. 煤炭科学技术,2020,48(3):133-139.FENG Yufeng. Research on top-coal caving mechanism and control technology in extra-thick coal seam with hard dirt band[J]. Coal Science and Technology,2020,48(3):133-139. [14] 邹光华,杨健男,关书方,等. 倾斜放煤口上下侧煤岩分界线方程表征及其模拟[J/OL]. 煤炭科学技术,1-13[2024-05-26]. http://kns.cnki.net/kcms/detail/11.2402.TD.20240227.1432.003.html.ZOU Guanghua,YANG Jiannan,GUAN Shufang,et al. Characterization and simulation of the coal-rock boundary equation on the upper and lower sides of the inclined coal caving opening[J/OL]. Coal Science and Technology, 1-13[2024-05-26]. http://kns.cnki.net/kcms/detail/11.2402.TD.20240227.1432.003.html. [15] 姜志刚,关书方,王明强,等. 大倾角综放面煤岩分界线不对称分布特征及放煤工艺优化[J]. 煤炭技术,2023,42(12):104-108.JIANG Zhigang,GUAN Shufang,WANG Mingqiang,et al. Asymmetric distribution characteristics of coal-rock boundary and optimization of coal caving technology in fully mechanized caving face with large dip angle[J]. Coal Technology,2023,42(12):104-108. [16] WANG Shuai,ZHANG Chunhua,HE Feng,et al. Numerical modelling of loose top coal and roof mass movement for a re-mined seam using the top coal caving method[J]. PLoS One,2023,18(4). DOI: 10.1371/JOURNAL.PONE.0283883. [17] LIU Yang,WANG Jiachen,YANG Shengli,et al. Improving the top coal recovery ratio in longwall top coal caving mining using drawing balance analysis[J]. International Journal of Mining,Reclamation and Environment,2023,37(5):319-337. doi: 10.1080/17480930.2023.2184036 [18] WEI Weijie,YANG Shengli,LI Meng,et al. Motion mechanisms for top coal and gangue blocks in longwall top coal caving (LTCC) with an extra-thick seam[J]. Rock Mechanics and Rock Engineering,2022,55(8):5107-5121. doi: 10.1007/s00603-022-02928-2 [19] 张文辉,李东印,王伸,等. 特厚煤层顶煤渐进破坏的块体−颗粒耦合模拟研究[J]. 河南理工大学学报(自然科学版),2022,41(6):24-35.ZHANG Wenhui,LI Dongyin,WANG Shen,et al. Study on block-particle coupling approach for modeling progressive failure of top coal in extra thick coal seams[J]. Journal of Henan Polytechnic University (Natural Science),2022,41(6):24-35. [20] ZHANG Qunlei,YUE Jinchao,LIU Chuang,et al. Study of automated top-coal caving in extra-thick coal seams using the continuum-discontinuum element method[J]. International Journal of Rock Mechanics and Mining Sciences,2019,122. DOI: 10.1016/j.ijrmms.2019.04.019. [21] 李东印,王耀闯,王伸,等. 特厚煤层综放开采顶煤遗失机理及放煤步距优化数值模拟研究[J]. 河南理工大学学报(自然科学版),2023,42(2):1-10.LI Dongyin,WANG Yaochuang,WANG Shen,et al. Numerical simulation study of top-coal loss mechanism and reasonable cycle step length for extra-thick coal seam top-coal drawing[J]. Journal of Henan Polytechnic University (Natural Science),2023,42(2):1-10. [22] 刘闯,李化敏,马占元,等. 不同煤厚综放工作面合理放煤工艺数值模拟研究[J]. 河南理工大学学报(自然科学版),2023,42(4):40-46.LIU Chuang,LI Huamin,MA Zhanyuan,et al. Numerical simulation study on reasonable top coal caving technology in longwall top coal caving working face with different top coal thickness[J]. Journal of Henan Polytechnic University (Natural Science),2023,42(4):40-46. [23] 董祥伟. 无网格弱可压缩SPH数值算法及应用扩展[M]. 北京:科学出版社,2021.DONG Xiangwei. Extension of meshless weakly compressible SPH numerical algorithms and applications[M]. Beijing:Science Publishing House,2021. [24] 张伟, 晏飞, 王兆丰, 等. 基于物质点和深度积分耦合模型的滑坡数值分析[J]. 岩土力学,2024,45(8):2515-2526.ZHANG Wei,YAN Fei,WANG Zhaofeng,et al. Numerical analysis oflandslides based on coupling modelof material point method and depth integral[J]. Rock and Soil Mechanics,2024,45(8):2515-2526. [25] FENG Ruofeng,FOURTAKAS G,ROGERS B D,et al. Large deformation analysis of granular materials with stabilized and noise-free stress treatment in smoothed particle hydrodynamics (SPH)[J]. Computers and Geotechnics,2021,138. DOI: 10.1016/J.COMPGEO.2021.104356. [26] 胡嫚,谢谟文,王立伟. 基于弹塑性土体本构模型的滑坡运动过程SPH模拟[J]. 岩土工程学报,2016,38(1):58-67.HU Man,XIE Mowen,WANG Liwei. SPH simulations of post-failure flow of landslides using elastic-plastic soil constitutive model[J]. Chinese Journal of Geotechnical Engineering,2016,38(1):58-67. [27] NGUYEN N H T,BUI H H,NGUYEN G D. Effects of material properties on the mobility of granular flow[J]. Granular Matter,2020,22(3). DOI: 10.1007/s10035-020-01024-y. [28] 高涛,谢守勇,胡嫚,等. 基于亚塑性本构模型的土壤−触土部件SPH互作模型[J]. 农业工程学报,2022,38(13):47-55.GAO Tao,XIE Shouyong,HU Man,et al. Soil-soil engaging component SPH model based on a hypoplastic constitutive model[J]. Transactions of the Chinese Society of Agricultural Engineering,2022,38(13):47-55.