多折定落点控爆拆除钢筋混凝土高烟囱设计原理

STUDY ON MULTIFOLDING-COLLAPSING ON SITE BLASTING DEMOLITION OF HIGH-RISE CHIMNEY OF REINFORCED CONCRETE

以广州纸厂高100m钢筋混凝土烟囱顺利实施定倒向、定落点、多折叠爆破拆除为例,提出了用多体-离散体系统动力分析来描述烟囱在初始失稳后到着地堆积的过程。多体-离散体动力分析方程由变拓扑多体系统动力学方程和离散体动力学方程组成,即变拓扑多体系统动力学方程来描述烟囱在初始失稳后,倾倒旋转和运动解体阶段,n折烟囱段在空中的动力运动,正算则数值模拟各拓扑的运动姿态,逆算烟囱各体间的作用力,以判断烟囱各段间相继的解体,其拓扑切换包括烟囱切口延时爆破的时间切换点、切口闭合的位移切换点和烟囱解体的动力切换点。空中解体后,用离散体系统动力分析方程来描述非完全离散直至完全离散体(含单体和多体)在空中的相互分离、钢筋牵拉、碰撞和滑移等下落运动,数值模拟烟囱各段塌落堆积的过程。现场观测的烟囱连续多折倾倒和解体的姿态以及着地堆积的形态,与数值模拟接近,证明了用多体-离散体动力分析来描述烟囱的爆破倒塌是正确的。

The paper brought forward an idea of using discrete multi-body system dynamics analysis（DMBA）for the description of the piling course of chimney which loses initial stability in its blasting demolition by taking the demolition of a 100m high chimney of reinforced concrete in Guangzhou Paper Mill,in which the directional blasting and multifolding collapsing to designed site were used for the demolition.The equations of DMBA were made up of dynamical equations of varying topological multibody system and discrete body system.The n folding chimney dynamics movement in space was described by dynamical equation of varying topological multibody system at the period of topple in a whirl and disintegrate moved after initial instability.Bodies movement in topological period was simulated numerically by computing the equation and force between bodies by inverse computing,judged body disintegrate.Varying topology covered the time point of delay blasting cuts,displace point of closing cuts and dynamical changing point of chimney discrete.After the disintegration,the downward movement of discrete bodies（single and multibody）was described by discrete body system dynamics equation,such as separate,steel pulling,crash and slide,process collapsed and collected of chimney bodies was simulated numerically.The condition,that multibody system changes into the initiation of discrete body system,was created by displace topological chang-ing of closing cuts.All the method used in the discussion on the demolition proved to be corrected.