Preliminary investigation on the deformation characteristics of lignite during dehydration process
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摘要: 为研究褐煤失水对露天矿煤岩组合边坡稳定性的影响，本文开展了褐煤失水试验，获得了岩样失水率、变形、孔隙率及裂纹演化规律，分析了岩样端面龟裂及分形渐变特征，探究了失水褐煤渐进损伤特性，基于毛细作用原理剖析了岩样裂纹扩展演化规律及作用机理。结果表明：褐煤恒温条件下，试件失水率呈“先陡后缓”的增长趋势，且最终接近或超过10 %；岩样逐渐产生轴向及环向变形，最终应变分别增至0.012 3和0.020 3，对应体积应变增至0.052 8，且应变增长与失水率渐变趋势相似；岩样失水体积远大于岩石收缩体积，孔隙率对应呈“先陡后缓”的增长趋势；岩样侧面横向裂纹渐进发育，且萌生位置渐变为“上端→下端→中部”，同时轴向裂纹萌生扩展，岩样端面龟裂特征显著，且裂纹分布分形维数基本呈线性增长趋势，揭示端面存在由均质向非均质转变过程；损伤变量随失水率呈非线性增长，最终增至0.066 5，且增长全程可分为线性增长阶段、减速增长阶段、加速增长阶段；受毛细作用控制，孔隙失水过程基质吸力增大是造成岩样轴向及横向收缩变形、竖向裂纹萌生扩展的主因。Abstract: In this paper, the water loss test was carried out to investigate the influence of lignite dehydration on the stability of coal-rock combination slope in open-pit mine.Firstly, the variation laws of water content, deformation, porosity and crack evolution of rock samples were obtained; secondly, the cracking fractal characteristics of sample's end face were analyzed; thirdly, the progressive damage characteristics of dehydrated lignite were studied; finally, based on the principle of capillarity, the law and mechanism of crack propagation for lignite were analyzed.The results show that under the condition of dehydration process, the water loss rate of rock samples presents an increasing trend of "first steep and then slow", and finally approaches or exceeds 10 %.The axial and circumferential deformation increases gradually for lignite samples, and the final strain increases to 0.012 3 and 0.020 3, respectively; meanwhile, the volumetric strain increases to 0.052 8 and has the similar growth trend to the water loss rate.The water loss volume of rock sample is much larger than that of shrinkage volume, and the porosity shows an increasing trend of "steep first and then slow".The lateral cracks of the rock sample develop gradually, and the propagation positions gradually change from upper end to bottom end, and finally to the middle of the rock; meanwhile, the axial cracks initiate and expand.The cracking characteristics of sample's end face are significant, and the fractal dimension of crack distribution shows a linear growth trend, which reveals that there is a transformation process from homogeneity to heterogeneity.The damage variable increases nonlinearly with the water loss rate, and finally increases to 0.066 5;meanwhile, the whole growth process can be divided into linear growth stage, deceleration growth stage, and accelerated growth stage.It is worth noting that the increase of matrix suction controlled by capillary action in the process of pore water loss can be account for the axial and circumferential shrinkage deformation of rock samples, and the initiation and propagation of vertical cracks.
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Key words:
- lignite /
- dehydration /
- porosity /
- cracking /
- damage /
- matrix suction
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图 3 褐煤岩样质量及失水率随时间演化特征
Figure 3. Evolution characteristics of quality and water loss rate of lignite samples
图 5 褐煤岩样体积及孔隙率变化特征
Figure 5. Variation characteristics of volume and porosity of lignite rock samples
图 6 A-1试件常温失水侧面裂纹渐进演化特征
Figure 6. Progressive evolution characteristics of side crack of A-1 sample at room temperature
图 7 A-1试件常温失水端面裂纹渐进演化特征
Figure 7. Progressive evolution characteristics of end face crack of A-1 sample at room temperature
图 8 A-1试件常温失水端面裂纹分形演化特征
Figure 8. Fractal evolution characteristics of end crack of A-1 sample at room temperature
图 9 褐煤岩样失水率与损伤变量演化关系
Figure 9. Relationship between water loss rate and damage variable of lignite rock samples
图 10 褐煤孔隙失水变形收缩机理
Figure 10. Deformation and shrinkage mechanism of pores by the gradual water loss of lignite
表 1 褐煤岩样XRF测试结果
Table 1. XRF test results of lignite rock samples
% 元素 Mg Al Si S K Ca Fe 总计 Wt 0.52 2.30 4.48 2.35 0.60 2.73 3.15 16.13 氧化物 MgO Al2O3 SiO2 SO3 K2O CaO Fe2O3 总计 Wt 0.82 4.03 8.29 4.54 0.52 2.64 2.72 23.56 
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表 2 褐煤岩样质量及尺寸参数统计
Table 2. Statistics of quality and size parameters of lignite samples
试件编号 质量/g 直径/mm 高度/mm 视密度/(kg·m-3) 初始 结束 浸水 初始 结束 浸水 初始 结束 浸水 初始 结束 浸水 A-1 227.75 200.75 222.40 49.02 47.66 48.66 99.22 97.20 100.18 1 213.13 1 158.28 1 194.37 A-2 232.54 212.66 230.44 48.80 47.96 48.78 99.60 98.54 101.32 1 243.41 1 159.21 1 217.61 A-3 232.04 186.76 231.96 49.02 48.32 48.94 104.06 103.32 105.10 1 182.12 986.22 1 173.85 A-4 231.84 210.84 231.62 48.70 47.64 48.64 99.88 98.76 101.36 1 246.76 1 198.28 1 230.41
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[1] 耿建纯, 刘文礼. 低阶煤中含氧官能团含量对浮选吸附概率的影响规律[J]. 矿业科学学报, 2016, 1(3): 284-290. http://kykxxb.cumtb.edu.cn/article/id/39Geng Jianchun, Liu Wenli. Effect of oxygen-containing functional groups on the attachment probability of low rank coals in coal flotation[J]. Journal of Mining Science and Technology, 2016, 1(3): 284-290. http://kykxxb.cumtb.edu.cn/article/id/39 [2] 宁可佳, 崔家画, 徐宏祥, 等. 褐煤反浮选试验工艺研究[J]. 矿业科学学报, 2021, 6(2): 228-236. doi: 10.19606/j.cnki.jmst.2021.02.011Ni Kejia, Cui Jiahua, Xu Hongxiang, et al. Lignite reverse flotation test process and mechanism[J]. Journal of Mining Science and Technology, 2021, 1(3): 228-236. doi: 10.19606/j.cnki.jmst.2021.02.011 [3] 宋银敏, 滕英跃, 李娜, 等. 胜利褐煤及盐酸洗煤热解过程中微结构演变特性研究[J]. 燃料化学学报, 2021, 49(4): 415-421. https://www.cnki.com.cn/Article/CJFDTOTAL-RLHX202104003.htmSong Yinmin, Teng Yingyue, Li Na, et al. Microstructural evolution during pyrolysis of Shengli lignite and hydrochloric acid-demineralized lignite[J]. Chinese Journal of Fuel Chemistry and Technology, 2021, 49(4): 415-421. https://www.cnki.com.cn/Article/CJFDTOTAL-RLHX202104003.htm [4] 王东, 姜聚宇, 韩新平, 等. 褐煤露天矿端帮开采边坡支撑煤柱稳定性研究[J]. 中国安全科学学报, 2017, 27(12): 62-67. https://www.cnki.com.cn/Article/CJFDTOTAL-ZAQK201712011.htmWang Dong, Jiang Juyu, Han Xinping, et al. Stability of supporting coal pillar for slope highwall mined in lignite surface mine[J]. Journal of China Safety Science, 2017, 27(12): 62-67. https://www.cnki.com.cn/Article/CJFDTOTAL-ZAQK201712011.htm [5] 刘建文. 胜利东二号露天矿顺倾软岩边坡开采过程稳定性分析与评价[D]. 徐州: 中国矿业大学, 2020. [6] Nakagawa H, Namba A, Bohlmann M, et al. Hydrothermal dewatering of brown coal and catalytic hydrothermal gasification of the organic compounds dissolving in the water using a novel Ni/carbon catalyst[J]. Fuel, 2004, 83(6): 719-725. doi: 10.1016/j.fuel.2003.09.020 [7] 刘英鹏, 杨晴, 胡敏, 等. 褐煤干燥后水分复吸规律及平衡含水率预测[J]. 煤炭学报, 2015, 40(11): 2661-2667.Liu Yingpeng, Yang Qing, Hu Min, et al. Investigation on the moisture reabsorption law of lignite after drying and the prediction of equilibrium moisture content[J]. Journal of China Coal Society, 2015, 40(11): 2661-2667. [8] 滕腾, 杜玉冰, 陈朋飞, 等. 砂岩变形率与水理效应的力学特性研究[J]. 矿业科学学报, 2020, 5(3): 342-352. http://kykxxb.cumtb.edu.cn/article/id/298Teng Teng, Du Yubing, Chen Pengfei, et al. Effects of deformation rate and hydrated condition on the mechanical property of sandstone[J]. Journal of Mining Science and Technology, 2020, 5(3): 342-352. http://kykxxb.cumtb.edu.cn/article/id/298 [9] 杨晓杰, 王嘉敏, 张民, 等. 大强煤矿深部巷道围岩吸水软化规律试验研究[J]. 矿业科学学报, 2017, 2(5): 432-438. http://kykxxb.cumtb.edu.cn/article/id/93Yang Xiaojie, Wang Jiamin, Zhang Min, et al. Study on strength softening of surrounding rock in deep roadway at Daqiang coal mine[J]. Journal of Mining Science and Technology, 2017, 2(5): 432-438. http://kykxxb.cumtb.edu.cn/article/id/93 [10] 姚强岭, 朱柳, 黄庆享, 等. 含水率对细粒长石岩屑砂岩蠕变特征影响试验研究[J]. 采矿与安全工程学报, 2019, 36(5): 1034-1042, 1051. https://www.cnki.com.cn/Article/CJFDTOTAL-KSYL201905024.htmYao Qiangling, Zhu Liu, Huang Qingheng, et al. Experimental study on the effect of moisture content on creep characteristics of fine-grained feldspar lithic sandstone[J]. Journal of Mining & Safety Engineering, 2019, 36(5): 1034-1042, 1051. https://www.cnki.com.cn/Article/CJFDTOTAL-KSYL201905024.htm [11] Ma Hongfa, Song Y anqi, Chen Shaojie, et al. Experimental investigation on the mechanical behavior and damage evolution mechanism of water-immersed gypsum rock[J]. Rock Mechanics and Rock Engineering, 2021, 54(9): 4929-4948. doi: 10.1007/s00603-021-02548-2 [12] 刘石, 许金余, 刘志群, 等. 温度对岩石强度及损伤特性的影响研究[J]. 采矿与安全工程学报, 2013, 30(4): 583-588. https://www.cnki.com.cn/Article/CJFDTOTAL-KSYL201304020.htmLiu Shi, Xu Jinyu, Liu Zhiqun, et al. Temperature effect on strength and damage property of rock mass[J]. Journal of Mining & Safety Engineering, 2013, 30(4): 583-588. https://www.cnki.com.cn/Article/CJFDTOTAL-KSYL201304020.htm [13] Zhou Zilong, Cai Xin, Cao Wenzhuo, et al. Influence of water content on mechanical properties of rock in both saturation and drying processes[J]. Rock Mechanics and Rock Engineering, 2016, 49(8): 3009-3025. [14] 胡玉, 邓华锋, 李建林, 等. 水-岩作用下砂岩微细观结构变化特性及机理研究[J]. 防灾减灾工程学报, 2018, 38(2): 265-273, 281. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXK201802009.htmHu Yu, Deng Huafeng, Li Jianlin, et al. Research on characteristics and mechanism of micro-structure variation in sandstone under water-rock interaction[J]. Journal of Disaster Prevention and Mitigation Engineering, 2018, 38(2): 265-273, 281. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXK201802009.htm [15] 邓华锋, 支永艳, 段玲玲, 等. 水-岩作用下砂岩力学特性及微细观结构损伤演化[J]. 岩土力学, 2019, 40(9): 3447-3456. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201909017.htmDeng Huafeng, Zhi Yongyan, Duan Lingling, et al. Mechanical properties of sandstone and damage evolution of microstructure under water-rock interaction[J]. Rock and Soil Mechanics, 2019, 40(9): 3447-3456. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201909017.htm [16] Song Yanqi, Ma Hongfa, Li Xiangshang, et al. Experimental investigation on the influence of water content on mechanical properties and failure characteristics of tuff[J]. Geotechnical and Geological Engineering, 2021, 39(4): 2871-2882. [17] 冯子军, 赵阳升. 煤的热解破裂过程——孔裂隙演化的显微CT细观特征[J]. 煤炭学报, 2015, 40(1): 103-108.Feng Zijun, Zhao Yangsheng. Pyrolytic cracking in coal: Meso-characteristics of pore and fissure evolution observed by micro-CT[J]. Journal of China Coal Society, 2015, 40(1): 103-108. [18] Han Jun, Zhang Li, Kim Hee Joon, et al. Fast pyrolysis and combustion characteristic of three different brown coals[J]. Fuel Processing Technology, 2018, 176: 15-20. [19] 张肖阳, 周滨选, 安东海, 等. 升温速率对准东褐煤热解特性及煤焦孔隙结构的影响[J]. 煤炭学报, 2019, 44(2): 604-610. https://www.cnki.com.cn/Article/CJFDTOTAL-MTXB201902030.htmZhang Xiaoyang, Zhou Binxuan, An Donghai, et al. Effect of heating rate on pyrolysis characteristics and char structure of Zhundong lignite coal[J]. Journal of China Coal Society, 2019, 44(2): 604-610. https://www.cnki.com.cn/Article/CJFDTOTAL-MTXB201902030.htm [20] 曾浩, 唐朝生, 刘昌黎, 等. 膨胀土干燥过程中收缩应力的测试与分析[J]. 岩土工程学报, 2019, 41(4): 717-725. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201904020.htmZeng Hao, Tang Chaosheng, Liu Changli, et al. Measurement and analysis of shrinkage stress of expansive soils during drying process[J]. Chinese Journal of Geotechnical Engineering, 2019, 41(4): 717-725. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201904020.htm [21] 骆赵刚, 汪时机, 张继伟, 等. 膨胀土裂隙发育的厚度效应试验研究[J]. 岩土工程学报, 2020, 42(10): 1922-1930. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC202010024.htmLuo Zhaogang, Wang Shiji, Zhang Jiwei, et al. Thickness effect on crack evolution of expansive soil[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(10): 1922-1930. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC202010024.htm [22] 黄达, 黄润秋, 张永兴. 粗晶大理岩单轴压缩力学特性的静态加载速率效应及能量机制试验研究[J]. 岩石力学与工程学报, 2012, 31(2): 245-255. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX201202004.htmHuang Da, Huang Runqiu, Zhang Yongxing. Experimental investigations on static loading rate effects on mechanical properties and energy mechanism of coarse crystal grain marble under uniaxial compression[J]. Chinese Journal of Rock Mechanics and Engineering, 2012, 31(2): 245-255. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX201202004.htm [23] 蔡永博, 王凯, 徐超. 煤岩单体及原生组合体变形损伤特性对比试验研究[J]. 矿业科学学报, 2020, 5(3): 278-283. http://kykxxb.cumtb.edu.cn/article/id/290Cai Yongbo, Wang Kai, Xu Chao. Comparative experimental study on deformation and damage characteristics of single coal rock and primary coal-rock combination[J]. Journal of Mining Science and Technology, 2020, 5(2): 278-283. http://kykxxb.cumtb.edu.cn/article/id/290 [24] Mandelbrot B B. Stochastic models for the Earth's relief, the shape and the fractal dimension of the coastlines, and the number-area rule for islands[J]. Proceedings of the National Academy of Sciences of the United States of America, 1975, 72(10): 3825-3828. [25] 刘冬桥, 张晓云, 何满潮, 等. 砂岩冲击岩爆实验碎屑研究[J]. 矿业科学学报, 2018, 3(3): 246-252. http://kykxxb.cumtb.edu.cn/article/id/144Liu Dongqiao, Zhang Xiaoyun, He Manchao, et al. Study on sandstone fragments from impact rockburst experiments[J]. Journal of Mining Science and Technology, 2018, 3(3): 246-252. http://kykxxb.cumtb.edu.cn/article/id/144 [26] 张娜, 赵方方, 张毫毫, 等. 岩石气态水吸附特性及其影响因素实验研究[J]. 矿业科学学报, 2017, 2(4): 336-347. http://kykxxb.cumtb.edu.cn/article/id/81Zhang Na, Zhao Fangfang, Zhang Haohao, et al. Experimental study on water vapor absorption of rock and its influencing factors[J]. Journal of Mining Science and Technology, 2017, 2(4): 336-347. http://kykxxb.cumtb.edu.cn/article/id/81 [27] 韩铁林, 陈蕴生, 师俊平, 等. 冻融循环下钙质砂岩力学特性及其损伤劣化机制的试验研究[J]. 岩土工程学报, 2016, 38(10): 1802-1812.Han Tielin, Chen Yunsheng, Shi Junping, et al. Experimental study on mechanical properties and damage degradation mechanism of calcareous sandstone subjected to freeze-thaw cycles[J]. Chinese Journal of Geotechnical Engineering, 2016, 38(10): 1802-1812. [28] 李思琪, 闫铁, 王希军, 等. 基于最小作用量原理的岩石微振动方程及分析[J]. 石油钻探技术, 2014, 42(3): 66-70. https://www.cnki.com.cn/Article/CJFDTOTAL-SYZT201403016.htmLi Siqi, Yan Tie, Wang Xijun, et al. The micro-vibration equation of rock and its analysis basing on the principle of least action[J]. Chinese Journal of Petroleum Drilling Techniques, 2014, 42(3): 66-70. https://www.cnki.com.cn/Article/CJFDTOTAL-SYZT201403016.htm -
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