冷却塔爆破拆除失稳机制与变形破坏特征研究

冷却塔为高耸薄壁结构,爆破拆除失稳机制复杂。依托H 70 m钢筋混凝土冷却塔爆破拆工程,通过多点无线高清摄像观测、支撑区动应变监测等手段,研究了冷却塔爆破拆除失稳过程中塔体的变形破坏特征和支撑区人字柱的应力演变机制。研究结果表明:切口区人字柱爆破时,首先产生向上的脉冲荷载,脉冲荷载沿塔壁传向支撑区人字柱,使其首先承受动态拉伸荷载;随后,支撑区人字柱首先整体向下压缩,然后发生回弹震荡;重力矩重新分配后,靠近切口区的人字柱承受应变率为10~(-3)/s~10~(-2)/s量级的动态附加压应力,人字柱与圈梁连接点产生压剪破坏;随着人字柱破坏范围的扩大,塔体转动轴逐渐后移,支撑区后部人字柱最终在圈梁节点处发生弯折破坏。

Study on Instability Mechanism and Deformation Characteristics of Hyperbolic Cooling Tower Explosive Demolition

The hyperbolic cooling tower is a high rise thin-walled structure,the instability mechanism in blasting demolition process is complicated.Combined with a H 70 m hyperbolic cooling tower blasting demolition project,the instability mechanism of columns in support zone and deformation-failure characteristics of the tower were studied by high-definition camera observation and strain monitoring.In cutting zone blasting,the upper part of the tower was loaded with an upward pulse load,and the pulse load would be transmitted to columns in support zone through the tower wall.As a result,the columns was subjected to additional dynamic tensile stress.Subsequently,columns in support zone were compressed downwards and then rebounded.After the gravity moment redistribution,columns near the blasting cut were subjected to comparable high strain rate(10-3/s~10-2/s) pressure,and the connection point between the columns and the ring beam had a compressive-shear failure.With the failure region expansion of the columns,the rotary axis of the support zone continuously moved backwards,and columns of backside were not destroyed by impact compression,but the bending failure came into being at the upper and lower nodes.