Aiming at directional blasting demolition engineering of chimney with blasting cut height at about 100 meters in the complex environment,in order to study the influence of the combination incision of triangle rectangular and inverted triangle rectangle for the collapse and stress changing process of chimney,two kinds of reinforced concrete chimney separated common node models were established and studied systematically using LS-DYNA software.The results shows that the neutral axis stabilization time of about 2-3 s (incision coefficient K =0.56-0.58) is the key to prevent too early sitting down and forming a directional dumping trend of the chimney after the formation of blasting incision;The compressive stress of the concrete inside the support body is greater than that of the outer concrete,the inverted triangle rectangle combination incision can delay the pressure shear failure and make the speed of neutral axis backward slower than the triangle rectangular combination incision,and is effective for the chimney to reach a safe and exact position.As the inverted triangle rectangle combination incision has some common features with the inverted trapezoidal and the inverted triangle trapezoid ones,the incision shape is recommended to use the inverted triangle in the directional blasting of high location incision of chimney.%针对复杂环境下爆破切口高度在百米位置的烟囱定向爆破拆除工程,为研究正三角矩形与倒三角矩形组合切口对烟囱爆破拆除倒塌及受力过程的影响,结合实际工程,利用LS-DYNA有限元软件分别建立两种切口形状下钢筋混凝土分离式共节点烟囱模型,对烟囱倒塌及受力过程进行了系统研究.结果表明,爆破切口形成后,约2～3s的中性轴稳定时间(切口系数K=0.56～0.58)是烟囱不出现过早下坐和形成定向倾倒趋势的关键条件;支撑部位内侧混凝土承受的压应力要大于外侧混凝土,倒三角矩形较正三角矩形组合切口能够延迟切口角端压剪破坏的发生,延缓支撑部位中性轴后移速度以及使支撑部位承受较高压应力,有利于烟囱避免过早下坐和安全精确定向;由于倒三角矩形组合切口与倒梯形、倒三角梯形组合切口具有一定共性,烟囱高位切口定向爆破切口形状建议优先采用倒三角型切口.
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