压缩脆性介质爆破破坏时冲击荷载与初始应力卸载特征  

Characteristics of shock load and initial stress unloading in blasting of compressed brittle medium

作　　者：姚颖康[1,2] 孙金山 贾永胜[2] 吴亮 倪明亮[1] 明胜[1] 陈洋 YAO Yingkang;SUN Jinshan;JIA Yongsheng;WU Liang;NI Mingliang;MING Sheng;CHEN Yang(Engineering Faculty,China University of Geosciences,Wuhan 430074,China;Hubei Key Laboratory of Blasting Engineering,Jianghan University,Wuhan 430056,China;College of Science,Wuhan University of Science and Technology,Wuhan 430081,China)

机构地区：[1]中国地质大学工程学院,武汉430074 [2]江汉大学爆破工程湖北省重点实验室,武汉430056 [3]武汉科技大学理学院,武汉430081

出　　处：《振动与冲击》2019年第24期257-266,共10页Journal of Vibration and Shock

基　　金：国家自然科学基金(51379194;41807265);湖北省自然科学基金面上项目(2017CFB310)

摘　　要：针对含压缩应变能脆性介质的爆破破坏机制问题,开展了建筑物底层立柱的现场爆破试验。分析了立柱保留部分的应变变化过程。动应变监测结果表明,炮孔炸药爆轰时,炮孔远区的爆炸荷载时程曲线大致呈三角形折线状,爆炸荷载升压阶段应变率高于卸压阶段;装药长度约20 cm时,爆炸荷载作用时间约为1 ms。爆炸冲击波作用消失后,由于碎块运动速度远低于冲击波和应力波传播速度,起爆后爆破介质的承载能力仍可保持数毫秒时间,此时介质主要受爆生气体膨胀作用,附加动应变较低。介质完全破碎后,碎块以较高的初速度发生抛掷飞散,其承载能力迅速消失,初始应变随之释放至0;应变释放的时程曲线接近于直线形,且卸载的应变率较低。构建了一维直杆的爆炸冲击与初始应力卸载力学模型,通过对直杆加载和卸载过程在时间域上的叠加,近似模拟了压缩立柱爆破时保留区的应变历程。对爆破试验的模拟表明,炸药爆炸作用结束数毫秒时间后初始应力才开始卸载。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.

关 键 词：爆破 爆炸荷载 初始应变 应变释放 应变监测 力学模型 

分 类 号：TU746[建筑科学—建筑技术科学]