不同加载速率下砂岩弯曲破坏的细观机理

李柯萱; 李铁

doi:10.11883/bzycj-2018-0178

不同加载速率下砂岩弯曲破坏的细观机理

doi: 10.11883/bzycj-2018-0178

李柯萱^{1, 2,},
李铁^{1, 2, ,}

1.
北京科技大学金属矿山高效开采与安全教育部重点实验室，北京 100083
2.
北京科技大学土木与资源工程学院，北京 100083

基金项目: 国家自然科学基金（51674016，51274025，51534002）

详细信息

作者简介:
李柯萱（1987－　），女，博士研究生, likexuan_456@163.com

通讯作者:
李　铁（1956－　），男，博士，教授，litie@ustb.edu.cn

中图分类号: O348.3; TU454
计量
- 文章访问数: 8716
- HTML全文浏览量: 2597
- PDF下载量: 168
- 被引次数: 0
出版历程
- 收稿日期: 2018-05-25
- 修回日期: 2018-08-27
- 刊出日期: 2019-04-01

Micro-mechanism of bending failure of sandstone under different loading rates

LI Kexuan^{1, 2
,},
LI Tie^{1, 2
, ,}

1.
State Key Laboratory of High-efficiency Mining and Safety of Metal Mines, Ministry of Education, University of Science and Technology Beijing, Beijing 100083, China
2.
School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China

摘要

摘要: 岩石细观破裂形貌是岩石破坏机制的重要反映，为研究不同加载速率对砂岩弯曲破坏的影响，通过三点弯曲实验和扫描电镜方法，对某煤矿关键层砂岩弯曲破断裂纹细观形态以及裂纹的自相似性进行了研究。选取6个不同加载速率对岩样进行三点弯曲实验，观察其宏观断裂情况，并利用扫描电镜对弯曲断裂面表面裂纹细观结构进行观察，并拍摄不同倍数下的扫描电镜图片。对图片进行图像处理后得到砂岩弯曲断裂破坏细观裂纹信息，并计算得到微裂纹的分形盒维数值。结果显示：随着加载速率的提高，砂岩穿晶断裂的比例也随之升高，裂纹分形维数亦随着加载速率的增大而增加，同时，分形维数还与弯曲断裂破坏荷载和抗弯强度成正比。可见，加载速率对断裂方式有一定的影响，且加载速率越大断裂所需的破坏能越大，裂纹分布越广，表明开采速度与岩爆等岩体动力灾变有密切关系。
- 三点弯曲 /
- 加载速率 /
- 岩石断口 /
- 细观形貌 /
- 分形维数
Abstract: The micro morphology of rock rupture is an important reflection of rock failure mechanism, in order to study the effect of different loading rates on the bending failure of sandstone, the microscopic morphology of the bending breaking cracks and the self-similarity of the cracks are analysed by scanning electron microscope combined with three point bending test. Selecting six different loading rates to test the rock samples to observe the macroscopic fracture condition and then the microstructure of surface cracks on bend fracture surfaces is observed by scanning electron microscope, and take SEM pictures at different multiplier. After the image is processed, getting the micro crack information of bending fracture of sandstone, and the fractal box dimension value of the micro crack is calculated. The results show that the proportion of transgranular fracture increases with the increase of loading rate; the crack fractal dimension also increases with the increase of loading rate, and at the same time, the fractal dimension is proportional to the bending fracture load and bending strength. It can be seen that the loading rate has a certain effect on the fracture mode, and the greater the loading rate is, the greater the failure energy requires, and the wider the crack distribution is, indicating that mining speed is closely related to rock burst and other dynamic catastrophe of rock mass.
- three point bending /
- loading rate /
- rock fracture /
- micromorphology /
- fractal dimension

HTML全文

图 1 破坏荷载的加载速率效应

Figure 1. Loading rate effect of failure load

下载: 全尺寸图片幻灯片

图 2 0.1、10和60 N/s加载速率下样品破坏照片

Figure 2. Specimen destruction under loading rates of 0.1, 10 and 60 N/s

下载: 全尺寸图片幻灯片

图 3 不同加载速率下样品的SEM图像

Figure 3. SEM images of samples at different loading rates

下载: 全尺寸图片幻灯片

图 4 SEM图像裂纹图像提取过程

Figure 4. Crack image extraction process of SEM photos

下载: 全尺寸图片幻灯片

图 5 分形盒维数法计算

Figure 5. Fractal dimension calculation in box counting

下载: 全尺寸图片幻灯片

图 6 加载速率和分形维数之间的关系

Figure 6. Relationship between fractal dimension and loading rate

下载: 全尺寸图片幻灯片

图 7 破坏荷载(P_t)、抗弯强度(R_t)与分形维数(D_s)的关系

Figure 7. Variation of failure load (P_t) and bending strength (R_t) with fractal dimension (D_s)

下载: 全尺寸图片幻灯片

表 1 岩石三点弯曲实验力学参数

Table 1. Mechanical parameters of rock three-point bending testing

加载速率/(N·s⁻¹)	编号	破坏荷载/kN	抗弯强度/MPa	加载速率/(N·s⁻¹)	编号	破坏荷载/kN	抗弯强度/MPa
0.1	A1	2.5		10	D1	2.86
	A2	2.61			D2	2.51
	A3	2.57			D3	2.94
	平均	2.56	6.144		D4	3.00
0.4	B1	2.58			平均	2.93	7.032
	B2	2.72		30	E1	3.34
	B3	2.68			E2	3.25
	平均	2.66	6.384		E3	3.47
1	C1	2.8			平均	3.35	8.040
	C2	2.99		60	F1	3.64
	C3	2.83			F2	3.48
	C4	2.71			F3	3.63
	平均	2.78	6.648		平均	3.56	8.544

下载: 导出CSV

表 2 砂岩试件裂纹分形维数

Table 2. Fractal dimension of cracks of sandstone

加载速率/(N·s⁻¹)	拟合公式	分形维数	加载速率/(N·s⁻¹)	拟合公式	分形维数
0.1	log₂N=−1.670 1 log₂a+2.696 6	1.670 1	10	log₂N=−1.717 7 log₂a+3.177 6	1.717 7
	log₂N=−1.665 3 log₂a+3.002 6	1.665 3		log₂N=−1.699 9 log₂a+2.316 7	1.699 9
	log₂N=−1.699 2 log₂a+2.737 6	1.699 2		log₂N=−1.705 5 log₂a+2.981 5	1.705 5
平均		1.678 2	平均		1.707 7
0.4	log₂N=−1.671 6 log₂a+3.257 5	1.671 6	30	log₂N=−1.736 6 log₂a+3.097 9	1.736 6
	log₂N=−1.683 5 log₂a+2.798 7	1.683 5		log₂N=−1.725 8 log₂a+3.011 8	1.725 8
	log₂N=−1.692 7 log₂a+3.127 6	1.692 7		log₂N=−1.742 6 log₂a+3.328 6	1. 742 6
平均		1.682 6	平均		1.735
1	log₂N=−1.698 7 log₂a+3.315 7	1.698 7	60	log₂N=−1.762 9 log₂a+2.923 0	1.762 9
	log₂N=−1.696 8 log₂a+3.255 3	1.696 8		log₂N=−1.749 8 log₂a+3.257 4	1.749 8
	log₂N=−1.703 6 log₂a+2.446 0	1. 703 6		log₂N=−1.764 6 log₂a+2.986 6	1.764 6
平均		1.699 7	平均		1.759 1

下载: 导出CSV

参考文献(18)

[1]	李德建, 关磊, 韩立强, 等. 白皎煤矿玄武岩岩爆破坏微观裂纹特征分析 [J]. 煤炭学报, 2014, 39(2): 307–313. DOI: 10.13225/j.cnki.jccs.2013.2013 LI Dejian, GUAN Lei, HAN Liqiang, et al. Analysis of micro-crack characteristics from rockburst failure of basalt in Baijiao Coal Mine content [J]. Coal society, 2014, 39(2): 307–313. DOI: 10.13225/j.cnki.jccs.2013.2013
[2]	易顺民, 赵文谦, 蔡善武. 岩石脆性破裂断口的分形特征 [J]. 长春科技大学学报, 1999, 29(1): 37–40. DOI: 10.13278/j.cnki.jjuese.1999.01.008 YI Shunmin, ZHAN Wenqian, CAI Shanwu. The fractal characteristics of brittle fracture appearance in rock [J]. Journal of Changchun University of Science and Technology, 1999, 29(1): 37–40. DOI: 10.13278/j.cnki.jjuese.1999.01.008
[3]	谢和平, 陈至达. 岩石断裂的微观机理分析 [J]. 煤炭学报, 1989, 6(2): 57–66. DOI: 10.13225/j.cnki.jccs.1989.02.009 XIE Heping, CHEN Zhida. Analysis of rock fracture miro-mechanism [J]. Journal of coal society, 1989, 6(2): 57–66. DOI: 10.13225/j.cnki.jccs.1989.02.009
[4]	DAUTRIAT J, BORNERT M, GLAND N. Micromechanical investigation of the hydromechanical behaviours of carbonates contribution of in-situ strain field measurement by means of SEM and optic digital image correlation [C] // Society of core analysts symposium. USA, 2013: 1−12.
[5]	刘云鹏, 邓辉, 黄润秋. 板裂结构岩石力学试验及破裂断口细观形貌特征分析 [J]. 岩石力学与工程学报, 2015, 34(2): 3852–3861. DOI: 10.13722/j.cnki.jrme.2014.0993 LIU Yunpeng, DENG Hui, HUANG Runqiu. Mechanical test of slab-rent structure rock and mesoscopic morphology analysis of rupture surface [J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(2): 3852–3861. DOI: 10.13722/j.cnki.jrme.2014.0993
[6]	李鹏, 饶秋华, 马雯波, 等. 脆性岩石热-水-力耦合断裂的断口分析 [J]. 岩石力学与工程学报, 2014, 33(6): 1179–1186. DOI: 10.13722/j.cnki.jrme.2014.06.011 LI Peng, RAO Qiuhua, MA Wenbo, et al. Coupled thermos-hydro-mechanical fractographic analysis of brittle rock [J]. Chinese Journal of Rock Mechanics and Engineering, 2014, 33(6): 1179–1186. DOI: 10.13722/j.cnki.jrme.2014.06.011
[7]	LI D, WANG G, HAN L, et al. Analysis of microscopic pore structures of rocks before and after water absorption [J]. Mining Science and Technology (China), 2011, 21(2): 287–293. DOI: 10.1016/j.mstc.2011.02.002.
[8]	CAI M, KAISER P K, TASAKA Y, el al. Generalized crack initiation and crack damage stress thresholds of brittle rock masses near underground excavations [J]. International Journal of Rock Mechanics and Mining Sciences, 2004, 41(5): 833–847. DOI: 10.1016/j.ijrmms.2004.02.001.
[9]	朱珍德, 张勇, 徐卫亚, 等. 高围压高水压条件下大理岩断口微观机理分析与试验研究 [J]. 岩石力学与工程学报, 2005, 24(1): 44–51. DOI: 10.3321/j.issn:1000-6915.2005.01.008 ZHU Zhende, ZHANG Yong, XU Weiya, et al. Experimental studies and microcosmic mechanics analysis on marble rupture under high confining pressure and high hydraulic pressure [J]. Chinese Journal of Rock Mechanics and Engineering, 2005, 24(1): 44–51. DOI: 10.3321/j.issn:1000-6915.2005.01.008
[10]	LI X, LOK T, ZHAO J. Dynamic characteristics of granite subjected to intermediate loading rate [J]. Rock Mechanics and Rock Engineering, 2005, 38(1): 21–39. DOI: 10.1007/s00603-004-0030-7.
[11]	赵康, 赵红宇, 贾群燕. 岩爆岩石断裂的微观结构形貌分析与岩爆机理 [J]. 爆炸与冲击, 2015, 35(6): 913–916. DOI: 10.11883/1001-1455(2015)06-0913-0 ZHAO Kang, ZHAO Hongyu, JIA Qunyan. An analysis of rockburst fracture micromorphology and study of its mechanism [J]. Explosion and Shock Wave, 2015, 35(6): 913–916. DOI: 10.11883/1001-1455(2015)06-0913-0
[12]	陈从新, 刘秀敏, 刘才华. 数字图像技术在岩石细观力学研究中的应用 [J]. 岩土力学, 2010, 31(S1): 53–60. DOI: 10.16285/j.rsm.2010.s1.044 CHEN Congxin, LIU Xiumin, LIU Caihua. Application of digital image processing to rock mesomechanics [J]. Rock and Soil Mechanics, 2010, 31(S1): 53–60. DOI: 10.16285/j.rsm.2010.s1.044
[13]	梁昌玉, 吴树仁, 李晓. 中低应变率范围内单轴压缩下花岗岩断口细-微观特征研究 [J]. 岩石力学与工程学报, 2015, 34(S1): 2977–2986. DOI: 10.13722/j.cnki.jrme.2014.0701 LIANG Changyu, WU Shuren, LI Xiao. Research on micro-meso characteristics of granite fracture under uniaxial compression at low and intermediate strain rates [J]. Rock Mechanics and Engineering, 2015, 34(S1): 2977–2986. DOI: 10.13722/j.cnki.jrme.2014.0701
[14]	彭瑞东, 鞠杨, 谢和平. 灰岩拉伸过程中细观结构演化的分形特征 [J]. 岩土力学, 2007, 28(12): 2579–2587. DOI: 10.3969/j.issn.1000-7598.2007.12.018 PENG Ruidong, JU Yang, XIE Heping. Fractal characterization of meso-structural evolution during tension of limestone [J]. Rock and Soil Mechanics, 2007, 28(12): 2579–2587. DOI: 10.3969/j.issn.1000-7598.2007.12.018
[15]	黄冬梅, 常西坤, 林晓飞, 等. 单轴压缩下岩石断口裂纹的分形特征研究 [J]. 山东科技大学学报, 2014, 33(2): 58–62. DOI: 10.16452/j.cnki.sdkjzk.2014.02.013 HUANG Dongmei, CHANG Xikun, LIN Xiaofei, et al. The fractal dimension of rock crack under uniaxial compression [J]. Journal of Shandong University of Science and Technology, 2014, 33(2): 58–62. DOI: 10.16452/j.cnki.sdkjzk.2014.02.013
[16]	Mandelbort B B. How long is the coast of Britain: Statistical self-similarity and fractional dimension [J]. Science, 1967, 156(3775): 636–638. DOI: 10.1126/science.156.3775.636.
[17]	LIU Q, SUN W. A Hilbert-type fractal integral inequality and its applications [J]. Journal of Inequalities and Applications, 2017, 2017(1): 83. DOI: 10.1186/s13660-017-1360-9.
[18]	姚哨峰, 张振南, 葛修润, 等. 大理岩断裂能与细观结构几何特征相关性 [J]. 岩土力学, 2016, 37(8): 2341–2346. DOI: 10.16285/j.rsm.2016.08.028 YAO Shaofeng, ZHANG Zhennan, GE Xiurun, et al. Correlation between fracture energy and geometrical characteristic of mesostructure of marble [J]. Rock and Soil Mechanics, 2016, 37(8): 2341–2346. DOI: 10.16285/j.rsm.2016.08.028