摘要
初步研究结果表明,高地应力条件下隧洞爆破开挖过程中围岩振动是由爆炸荷载所诱发的振动和开挖轮廓面上的地应力动态卸载所诱发的振动叠加而成,但在实测的时域振动波形中,这2种荷载所分别诱发的振动并没有明确的分界点,这给地应力动态卸载研究带来很大不便,而确定此分界点是分离动态卸载振动的关键一步。将爆炸荷载和地应力动态卸载均看作振动激励源,那么它们都将使振动信号的能量产生突变,而小波变换的时–能密度法具有突出被分析信号能量突变的特点。利用这一原理,通过对比分析瀑布沟水电站地下厂房爆破过程中实测单段围岩振动波形的能量随时间的分布情况,有效识别地应力动态卸载振动到达的时刻。分析结果表明,地应力动态卸载所诱发的围岩振动滞后爆炸荷载所诱发的围岩振动数十毫秒,滞后时间的长短主要受爆破台阶高度或者炮孔深度和炮孔间距的控制,台阶高度或者炮孔深度越大,滞后时间越长。该工作为从实测波形中分离出动卸载振动打下了基础。
The primary study indicates that the vibration monitored in the process of blasting-excavation in high geostress zone is constituted of vibration induced by blasting load（VIB） and vibration induced by geostress dynamic unloading（VIDU）. But the two components of the monitored vibration have no clearly dividing point at time. It＇s very inconvenient to study the VIDU. Achieving the time-dividing point between VIB and VIDU is the first procedure for separating the VIDU from the total vibration of surrounding rock. The blasting load and the dynamic unloading of geostress can be taken as the excitation source of vibration signals, and both of them will make the signals jump at the very time when they take place. The time-energy density analysis（TEDA） based on the wavelet transform has the character of making the abrupt change of signal energy prominently. So, the TEDA method is used to analyze the energy distribution of total vibration versus time monitored during the blasting-excavation in Pubugou hydropower station with high geostress, and the arriving moment of the VIDU in every delay of total vibration is identified effectually. The analysis result reveals that the arriving time of VIDU falls behind the VIB about several tens of milliseconds, and the time delay is determined by the height of blast-bench, the borehole-depth and the borehole-space. The larger the stage-height or the borehole-depth is, the larger the delay time is. The researches lay down a good foundation for separating the VIDU from field vibration of surrounding rock during blasting.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2009年第A01期2836-2844,共9页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金面上项目(50779050)
湖北省自然科学基金杰出青年人才项目(2007ABB026)
国家自然科学基金委员会和雅砻江水电开发联合基金资助项目(50639100)
教育部新世纪优秀人才计划资助项目
关键词
岩石力学
地应力
围岩振动
小波变换
时-能分析
动态卸载
rock mechanics
geostress
vibration of surrounding rock
wavelet transform
time-energy analysis dynamic unloading
