爆破拆除楼房时塌落振动的预测

Prediction of collapse vibration of building demolished by blasting

从十余栋楼房塌落振动综合实测中可见,峰值振速总是由楼房倒塌触地的姿态所决定,即可能发生在后支撑爆破楼房下坐、切口闭合或翻倒触地时,且峰值也不尽相同。由此,在量纲分析中引入重心下落高度,分别建立了楼房下坐、楼房切口闭合冲击和建(构)筑物整体翻倒触地振动的峰值振速经验公式,阐述了相应的楼房、建(构)筑物不同塌落振动原理,并从案例实测振速对数图峰值最大包络线中,摄取公式待定参数Kt、β,由此分别提出对应的峰值振速算法的计算公式,并阐明参数的物理意义和取值。预测地点振速可先按结构选取,高大烟囱、现浇剪力墙(包括前跨现浇剪力墙的框剪结构及13层以上的单向倾倒现浇框剪结构的前方预测点)的塌落峰值振速,选取算法(3)计算峰值振速。框架和其他框剪楼房塌落振动的峰值,可按触地姿态选取算法(1)和算法(2)计算,并选取算法中的较大计算值为预测的峰值振速。由于补充了算法(1)和算法(2),综合算法正确地反映了形成峰值振速的楼房触地位置和撞地冲击时重心改变的高度,因此振动原理较明确,由此提高了预测塌落振动的针对性和准确性。并结合观测实例进行了公式验证,证明了公式的合理性。

More than ten buildings collapse vibration were comprehensively measured,and peak vibration velocity was always determined by building collapse touchdown attitude,it′s likely to occur in rear support sitting down by blasting,incision closure or toppling on ground,and the peak values were not same.Therefore,falling height of the center of gravity was introduced in dimensional analysis,the empirical formula of the peak value of vibration speed of buildings sitting down,incision closure shock and building(structure)overturned wholly on ground were respectively established.Different collapse vibration principle were correspondently described.Formula parameters Ktandβwere taken out from the peak envelope line of case in measured velocity logarithmic graph.Formulas respectively corresponding to peak velocity algorithms were proposed,and physical meaning of parameters and values were explained.According to the structure selected,high chimneys,cast-in-place shear wall(including the former cross cast-in-place shear wall ahead of frame and front site of cast-in-situ frame shear wall structure more than 13storeys),prediction collapse vibration peak velocity was calculated by algorithm(3).Frame and other shear wall frame buildings collapse vibration peak was calculated by touchdown attitude to select algorithm(1)and(2),the vibration velocity greater was selected for the prediction vibration value.Algorithm(1)and(2)were supplemented,integrated new algorithm correctly reflected touchdown position of formation of vibration wave peak of building and the changed height of the center of gravity of impact hit on ground,so the principle of vibration was more explicit and the pertinence and accuracy of collapse vibration predicted would be improved.The observed examples were listed and the rationality of the formulars were proved.