摘要:
对药量达50t的科学爆破开展了流动强震观测,包括爆破振动的衰减观测和地形效应观测。在分 析此次爆破强震记录的基础上,利用萨道夫斯基公式分析了垂直向峰值速度和加速度的衰减规律,爆破地区 为中等强度的层状岩石且当地地形沟壑纵横是此次振动能量衰减较快的原因。通过离散小波变换分析(db8 小波基函数)得到了此次爆破振动能量的时频分布规律,随着爆心距的增大,爆破振动能量集中的频率减小而 振动的持续时间则相对增加。根据中国地震烈度表,在近爆心区振动烈度可以达到Ⅶ度,然而相对于天然地 震的烈度衰减,爆破振动烈度的衰减较快。通过比较一个高14m 山包的不同位置的强震记录,分析了此次 爆破振动的地形效应。由于山包的聚焦效应,山顶的加速度峰值是山脚的2.4倍,且地形效应对某频率段内 的振动有选择的放大,该频率段与山包的大小和高度有关。振动轨迹图显示,随着高度的增加,山体的侧向摆 动和转动逐渐增强。
Abstract:
Vibrationattenuationandtopographiceffectweremonitoredneartheexplosionplaceof50t explosive.Basedontherecordedvibrationsignals,theattenuationsofverticalvelocityandaccelerationwereanalyzedwiththeSadauskasformula. Therapidattenuationofvibrationwasrelatedwith thelayeredmoderate-hardnessrocksandthelocalterrainandgully.Thetime-frequencydistribution ofthevibrationwasobtainedbythediscretewavelettransform (db8wavelet).Thefrequencyofvibrationenergyconcentrationwasreducedandthedurationofthevibrationwasprolongedwiththeincreaseofthedistancefromt eexplosioncenter.AccordingtotheChineseSeismicIntensityScale,the vibrationintensityclosetotheexplosioncenterisuptoⅦ,however,theblastingvibrationintensity decayfasterthantheattenuationofearthquakeintensity.Thetopographiceffectwasdiscussedby comparingthevibrationrecordsatdifferentlocationsofa14-m-highhill.Duetothefocusingvibrationenergyofthehill, thepeakaccelerationonthetopofthehillis2.4timeslargerthanthatatthe footofthehill,andthespecialfrequencybandswiththeenlargedamplitudeisrelatedwiththesize andtheheightofthehill.Thefigureofparticlemotionsindicatesthatthelateralswingandrotational motiongraduallyincreasefromthefoottothetopofthehill.
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