| 褐煤失水形变特性研究初探 |
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| 作者姓名： | 宋彦琦 马宏发 郑俊杰 杨敏健 申付新 邵志鑫 |
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| 作者单位： | 1.煤炭资源与安全开采国家重点实验室，北京 100083 |
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| 基金项目： | 煤炭资源与安全开采国家重点实验室开放基金SKLCRSM20KFA1深部岩土力学与地下工程国家重点实验室开放基金SKLGDUEK2017 |
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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。
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| 关 键 词： | 褐煤 失水 孔隙率 龟裂 损伤 基质吸力 |
| 收稿时间： | 2021-12-22 |
Preliminary investigation on the deformation characteristics of lignite during dehydration process |
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| Affiliation: | 1.State Key Laboratory Coal Resource and Safe Mining, Beijing 100083, China2.School of Mechanics and Civil Engineering, China University of Mining and Technology-Beijing, Beijing 100083, China |
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| 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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