Characteristics of shock load and initial stress unloading in blasting of compressed brittle medium
YAO Yingkang1,2, SUN Jinshan1, JIA Yongsheng2, WU Liang3, NI Mingliang1, MING Sheng1, CHEN Yang3
1.Engineering Faculty, China University of Geosciences, Wuhan 430074, China;
2.Hubei Key Laboratory of Blasting Engineering，Jianghan University, Wuhan 430056, China;
3.College of Science, Wuhan University of Science and Technology, Wuhan 430081, China
Abstract：In order to study the blasting mechanism of brittle medium containing compress strain energy, the filed blasting experiments of the first-floor columns of high buildings were conducted, and the strain of the reserved part of the columns was monitored.The strain monitoring result shows that during the blasting process, when explosive in blasting hole is initiated, the time history curve of blasting load far from the blasting hole is approximately in the shape of triangle, and the strain rate in load increasing stage is higher than that in load decreasing stage.If the charge length is about 20 cm, the time of the explosion shock is about 1 ms.After the explosion shock wave disappears, the bearing capacity of the blasted medium can be maintained for several milliseconds after the detonation, because the moving speed of the fragment is much lower than the shock wave and the stress wave propagation speed.At this time, the medium is mainly affected by the explosive gas and the additional dynamic strain far from blasting holes is low.When the medium is completely destroyed, the fragments are thrown at a high initial velocity, and its bearing capacity disappears rapidly, then the initial strain rapidly releases to 0.The monitoring results show that the time history curve of strain relief is close to a straight line.The mechanical model of one-dimensional bar is deduced to analyze the explosion shock and initial stress relieving process.Through the superposition of the loading and unloading process of the straight bar in the time domain, the strain history of the reserved zone in the compression column blasting was simulated.The simulation of the blasting experiment shows that the initial stress began to unload after a few milliseconds of explosive shock.
姚颖康1，2，孙金山1，贾永胜2，吴亮3，倪明亮1，明胜1，陈洋3. 压缩脆性介质爆破破坏时冲击荷载与初始应力卸载特征[J]. 振动与冲击, 2019, 38(24): 257-266.
YAO Yingkang1,2, SUN Jinshan1, JIA Yongsheng2, WU Liang3, NI Mingliang1, MING Sheng1, CHEN Yang3. Characteristics of shock load and initial stress unloading in blasting of compressed brittle medium. JOURNAL OF VIBRATION AND SHOCK, 2019, 38(24): 257-266.
[1] 刘殿书，王万富，杨吕俊，谢夫海. 初始应力条件下爆破机理的动光弹实验研究[J].煤炭学报, 1999, 24(6): 612-614.
LIU Dian-shu, WANG Wan-fu, YANG Lu-jun, XIE Fu-hai, Holophotoelasticity study on mechanism of blasting under initiative stress field[J]. JOURNAL OF CHINA COAL SOCIETY,1999,24(6):612-614.
[2] 张志呈，肖正学，胡健，李春晓，张渝疆. 岩体爆震传播时应力场的波导效应试验研究[J].化工矿物与加工,2005(7):21-24.
ZHANG Zhi-cheng, XIAO Zheng-xue, HU Jian, LI Chun-xiao, ZHANG Yu-jiang. Experimental study on the wave transmission effect of the initial stress field as transmitting of quake wave from rock blasting[J]. Industrial Minerals & Processing,2005(7):21-24.
[3] 张正宇,刘颖,张文煊. 东风水电站地下厂房爆破振动效应的研究[A]. 工程爆破文集(第五辑)[C].1993,299-305.
ZHANG Zheng-yu, LIU Ying, ZHANG Wen-xuan. Study on Blasting Vibration Effect of Underground Powerhouse of Dongfeng Hydropower Station[A]. Collection of engineering blasting(fifth)[C]. 1993, 299-305.
[4] Abuov M G, Aitaliev S M, et al. Studies of the effect of dynamic processes during explosive break-out upon the roof of mining excavations[J]. Soviet Mining Science,1989, 24(6):581-590.
[5] Carter J P& Booker J R. Sudden Excavation of a Long Circular Tunnel in Elastic Ground [J]. International Journal of Rock Mechanics & Mining Sciences & Geomechanics. Abstract, 1990, 27(2):129-132.
[6] 卢文波, 周创兵, 陈明,等. 开挖卸荷的瞬态特性研究[J]. 岩石力学与工程学报, 2008, 27(11): 2184–2192.
LU Wen-bo. ZHOU Chuang-bing, CHEN Ming. et a1. Research on transient characteristics of excavation unloading[J]. Chinese Journal of Rock Mechanics and Engineering, 2008, 27(11): 2184-2194.
[7] 严鹏,卢文波,许红涛.高地应力条件下隧洞开挖动态卸荷的破坏机制初探[J].爆炸与冲击,2007,27(3): 283-288.
YAN Peng, LU Wenbo, XU Hongtao. A primary study of damage mechanism of initial stress dynamic unloading when excavating under high geostress condition[J]. Explosion and Shock Waves, 2007, 27(3): 283–288.
[8] 孙金山，金李，姜清辉，周传波，卢文波. 地下洞室爆破开挖过程中地应力瞬态调整诱发节理围岩松动机制研究 [J]. 振动与冲击,2011，30（12）：28-34.
SUN Jin-shan, JIN Li, JIANG Qing-hui, ZHOU Chunan-bo, LU Wen-bo. Loosing mechanism of jointed rock mass induced by transient adjustment of in-situ stress[J]. JOURNAL OF VIBRATION AND SHOCK, 2011，30（12）：28-34.
[9] 祝启虎. 地应力瞬态卸荷对围岩损伤特征的影响[博士]. 武汉: 武汉大学,2010.
Zhu Qi-hu. Influence on Damage Characteristics of Surrounding Rock induced by In-situ Stress Transient Unloading[D]. Wuhan: Whuhan University,2010.
[10] J. Henrych. The Dynamics of Explosion and Its Use[M]. New York：Elsevier Scientific Publishing Company，1979.
[11] Swoboda G.，Aenz G. Practical considerations of blasting loading using numerical modeling[A]. In: Proceedings of the Sixth International Conference on Numerical methods in geomechanics[C]，1988. 1681-1688.
[12] 朱瑞庚，王雪锋. 不耦合装药爆破孔壁压力的计算(1)[J]. 爆破，1990，7(3)：1-4.
Zhu Rui-geng,WANG Xue-feng. Calculation of wall pressure of uncoupled charge blasting holes (1)[J].Blasting，1990，7(3)：1-4.
[13] S.G.Chen，J.Zhao，Y.X.Zhou. UDEC modeling of a field explosion test[J]. International Journal of Blasting and Fragmentation，2000，4:149-163.
[14] 张建华，李世禄，王玉杰，李守贵. 爆炸扩腔数值模拟及分析[J]. 武汉科技大学学报(自然科学版), 2001, 24(2):174-177
ZHANG Jian-hua, LI Shi-lu, WANG Yu-jie, LI Shou-gui. Numerical Simulation of Springing Blasting in Stemmed Hole[J]. Journal of Wuhan University of Science and Technology(Natural Science Edition), 2001, 24(2):174-177.
[15] 张正宇,张文煊，吴新霞. 现代水利水电工程爆破[M]. 北京:中国水利水电出版社,2003
ZHANG Zheng-yu, ZHANG Wen-xuan, Wu Xin-xia. Modern Blasting Technology of Water Resources and Hydropower Engineering[M]. Beijing: China water conservancy and hydropower press,2003.
[16] 徐国元，段乐珍，闫长斌 .约束爆炸加载在混凝土中产生的径向应变效应[C].第七届全国爆炸力学学术会议，2003.
XU Guo-yuan, DUAN Chang-le, YAN Chang-bin. Radial Strain Effect in Concrete Due to Constrained Explosion Loading[C].The 7th national conference of explosive mechanics,2003.
[17] Arfken G B, Weber H J, Harris F E. Mathematical Methods for Physicists (Seventh Edition)[M]. 2012.
[18] 同济大学应用数学系. 高等数学（第6版）[M]. 北京: 高等教育出版社, 2007.
Department of Applied Mathematics of Tongji University. Advanced Mathematics(6th Edition)[M]. Beijing: Higher Education Press, 2007.
[19] 刘延柱, 陈文良, 陈立群. 振动力学（第2版）[M]. 高等教育出版社, 2011.
Liu Yan-zhu, Chen Wen-liang, Chen Li-qun. Vibration mechanics(Second Edition)[M]. Higher Education Press, 2011.
[20] 谭述君, 钟万勰. 非齐次动力方程Duhamel项的精细积分[J]. 力学学报, 2007, 39(3):374-381.
TAN Shu-jun, ZHONG Wan-xie. Precise integration method for Duhamel terms arising from non-homogenous dynamic systems[J]. Chinese Journal of Theoretical and Applied Mechanics, 2007, 39 (3): 374-381
