【作者】 王斌；

【导师】 梁开水； 张建华；

【作者基本信息】 武汉理工大学 ， 采矿工程， 2003， 硕士

【摘要】 定向爆破拆除砌体高耸建筑物时，中上部结构的过早断裂问题严重影响到定向爆破的安全可靠。过早断裂出现与否取决于爆破切口瞬间形成的情况。但此方面的理论分析目前尚处于初级探索阶段，实践中仍然依靠经验。为此，本文借助大型有限元分析研究软件ANSYS，建立大量不同参数的烟囱三维实体模型，通过数值模拟与理论分析对切口参数、爆破荷载，风荷载等因素对切口瞬间形成及结构中上部的影响进行研究。针对高耸建筑物爆破拆除的设计原则，本文的研究结果提出了改进建议，为实际的爆破施工提供依据。取得了如下主要成果： 爆破切口参数方面，爆破切口高度按壁厚的1.5～3.0倍作为爆破设计的取值时，下限值范围偏大，系数应取2.0～3.0；爆破切口长度按烟囱底部周长的60％～66％取值时，切口长度偏大固然不可取，而过于保守同样是不可取的，范围在62％～64％是比较合理的；在常用的正梯形、倒梯形、矩形爆破切口形状中，以正梯形效果最好。 将ANSYS5.7瞬态动力学分析引入爆破动力计算中，定量分析研究了在切口形成时的爆破振动荷载下，整体结构受力过程及应力分布规律。爆破切口形成产生爆破荷载对上部结构的断裂有相当影响，是简体反向倾转及过早断裂的主要原因。爆破荷载作用下，烟囱筒体高度58％～75％范围内是危险区。对风化严重等强度低的砖烟囱进行爆破拆除时，尤其要控制单响起爆药量与起爆的间隔时间。在同样条件下，烟囱强度低也是造成倾倒过程过早断裂的又一个原因。 探讨爆破拆除高耸建筑物中风荷载的特点与计算方法，通过数值模拟对风荷载在拆除爆破中影响高耸结构倾转进行定量分析，确定风荷载的影响程度。 数值模拟结果客观的再现了不同切口参数条件下的实体模型的受力情况，爆破振动荷载的数值分析与实际结果相吻合，也证明了数值模拟方法在高耸建筑物爆破拆除中的适用性和科学性。更多还原

【Abstract】 During the directional blasting demolition of a brick towering building, security of the directional blasting was influenced seriously by the premature rupture near the middle part of the towering building. Whether the premature rupture appears or not depends on the status of blasting cut shaped instantly. However, for the lack of research on problems such as the premature rupture, most blasting projects still rely on experiential theories. By means of commercial FEA software ANSYS, FEA three-dimensional chimney models are established. And various factors that affect the forming of blasting cut and damage in the middle part of the chimney, including parameters of blasting cut, load of blasting vibration and wind, are deeply analyzed by theoretical methodology and numerical simulation. According to the result of this paper, the design principle of demolition blasting in towering buildings can be proposed and applied to practical blasting projects. And main conclusions can be shown as follows:First, the optimum parameters of blasting cut are presented. In choosing the height of blasting cut, 2 .0 to 3.0 times of the wall widths of a towering building are used instead of from 1.5 to 3.0. And the lengths of blasting cut that range from 62% to 64% of the bottom perimeter of a towering building should be more reasonable than from 60% to 64%. No doubt adopting the upper limit is not suggested, but the conservative percent should not be adopted neither. In addition, echelon is the best shape of blasting cut among echelon, inverse echelon and rectangle.Transient dynamical FEA of ANSYS 5.7 is applied in calculation of demolition blasting. In quantitatively analysis including process of loading and stress distribution along the body of a chimney, load of blasting vibration induced by the forming of blasting cut was analyzed and the premature rupture of upper chimney was certainly affected by it. And it is also the main reason that induces the premature rupture and the reverse collapse of a chimney. Under blasting vibration load, the dangerous zonesrange from 58% to 75% of the chimney body. Considering the situation that the chimney was weathered seriously and the strength was so lower that single charge and blasting delay interval should be well-chosen especially. On the same condition, it is another reason that the premature rupture induced by the low strength of a chimney.Characteristics and calculational methods of wind load are discussed in this paper. The extent of impact of wind load is analyzed quantitatively by means of numerical simulation, especially when the towering building rotates after blasting.The process of stress change near the blasting cut was displayed objectively by the numerical simulation in different solid FEA models. Moreover, results of numerical analysis in blasting vibration load agree with the practical results, which show that ANSYS can be helpful to design and optimize the parameters of demolition blasting.更多还原