超临界CO2-水-煤相互作用后冲击载荷下煤的动态响应

Title

Dynamic response of coal under impact load after supercritical CO2 -water-coal interaction
作者

杜秋浩刘晓丽王维民王恩志钟建文王思敬
Author

DU Qiuhao1 ,LIU Xiaoli1,2 ,WANG Weimin1 ,WANG Enzhi1,2 ,ZHONG Jianwen1 ,WANG Sijing1,3
单位

清华大学水沙科学与水利水电工程国家重点实验室清华大学三江源协同创新中心中国科学院地质与地球物理研究所
Organization

1. State Key Laboratory of Hydro-Science and Engineering,Tsinghua University,Beijing　 100084,China; 2. Sanjiangyuan Collaborative Innovation Center, Tsinghua University,Beijing　 100084,China; 3. Institute of Geology and Geophysics of the Chinese Academy of Sciences,Beijing　 100029,China
摘要

CO₂地质封存是一种能有效降低大气中CO₂浓度的手段。我国存在大量关闭/废弃矿井且其地下空间并未得到有效利用，埋深超过800 m的关闭/废弃矿井是CO₂封存的潜在目标。关闭/废弃矿井具有复杂的应力场、水动力场和化学场，大规模CO₂注入后可能会诱发断层活化，进而造成动力灾害。为研究CO₂注入关闭/废弃矿井中煤的力学行为，利用50 mm分离式Hopkinson压杆(SHPB)试验装置，对自然状态、饱水状态和超临界CO₂-水-煤作用后煤样分别进行动态压缩试验，分析3种状态煤样试件在冲击载荷作用下的破坏形态、能量特征以及动态力学参数。试验结果表明:① 随应变率增高，相对于自然和饱水状态煤样，超临界CO₂-水-煤相互作用后煤样的破碎块度数量更多，碎块粒径更小;② 随入射能增大，3种状态煤样的能量反射率、透射率及耗散率的线性变化趋势不同，超临界CO₂-水-煤相互作用后煤样的能量反射率显著增高，能量耗散率显著降低;③ 超临界CO₂-水-煤作用后煤岩材料性质发生弱化，在冲击载荷下通过微裂隙萌发扩展来提高耗散能密度，其动态抗压强度和动态弹性模量与耗散能密度间关系介于自然和饱水状态煤样之间。本次试验证实CO₂-水-煤作用过程中发生的矿物化学反应、吸附膨胀诱导微观结构改变、裂隙表面能降低等因素能够明显影响煤样的动态响应特征。尽管本文的试验不能完全反映关闭/废弃封存CO₂的真实情况，但为后续CO₂-水-煤相互作用下煤样动态响应特征研究提供了借鉴。
Abstract

In order to study the mechanical behavior of coal after CO2 injection in closed / abandoned mines,the ϕ50 mm split Hopkinson pressure bar (SHPB) test system was used. This dynamic compression tests were carried out on the natural state coal, saturated state and supercritical CO2 -water-coal interacted coal samples. Thus, the failure modes,energy characteristics and dynamic mechanical parameters of three state coal samples under impact load were analyzed. The test results show that ① with the increase of strain rate,compared with the natural and saturated state coal samples,the coal samples treated by supercritical CO2 -water-coal interaction have more fragments and smaller particles. ② With the increase of incident energy,the linear trend of energy reflectance,transmittance and dissipation rate of three state coal samples are different. Coals after supercritical CO2 -water-coal interaction show that if energy reflectivity significantly increase,the energy dissipation rate will significantly decrease. ③ Compared with the natural and saturated state coal samples,the properties of coal are weakened after supercritical CO2 -water-coal interaction,and the dissipated energy density is increased by the micro-crack germination expansion under impact load. Besides,the curves of dynamic compressive strength-dissipated energy and dynamic elastic modulus-dissipated energy density vibrate be-tween natural state and saturated state. The experimental results show that the factors such as mineral chemical reac-tion,microstructure change induced by adsorption expansion,and surface energy reduction of cracks can significantly affect the dynamic response characteristics of coal samples. Although the experimental methods in this paper cannot fully reflect the real situation of CO2 storage in closed / abandoned,this study provides a relevant reference information for the further research of the dynamic response characteristics of coal samples under the CO2 -water-coal interaction.
关键词

CO2封存 CO2-水-煤作用分离式霍普金森压杆冲击荷载能量
KeyWords

CO2 sequestration;CO2 -water-coal interaction;SHPB;impact load;energy
DOI

10. 13225 / j. cnki. jccs. 2019. 0056
Citation

DU Qiuhao,LIU Xiaoli,WANG Weimin,et al. Dynamic response of coal under impact load after supercritical CO2 -water-coal interaction[J]. Journal of China Coal Society,2019,44(11):3453-3462.
图表

煤样试件

XRD检测图谱

SEM-EDS微观结构扫描及其面元素分布

高温高压反应釜试验系统示意

SHPB试验系统

SHPB冲击试验

煤样试件SHPB测试力平衡曲线

3种状态煤样试件在不同应变率下破坏形态

煤样试件动态压缩过程中波形图与对应能量变化时程曲线(试件编号SC-6,v=8．89m/s)

能量反射率、透射率、耗散率与入射能量间关系

耗散能密度与平均应变率关系

动态抗压强度与耗散能密度关系

动态性模量与耗散能密度关系

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