Based on blasting demolition of high thin-wall hyperbolic reinforced concrete cool tower, by virtue of engineering practice of blasting the tube concrete structures, the analysis and research were made on the mechanis...Based on blasting demolition of high thin-wall hyperbolic reinforced concrete cool tower, by virtue of engineering practice of blasting the tube concrete structures, the analysis and research were made on the mechanism of cool tower collapse through selecting blasting parameters and selecting gap form, gap size and gap angle. The cool tower was twisted, collapsed directionally and broken well according to the design requirements. The expected results and purposes of blasting were obtained with no back blow, total blasted pile approximates to 4 - 5 m, no occurrence of flying stones and no damage to fixed buildings and equipment, the large-sized hyperbolic thin-wall reinforced concrete cool towers are twisted during blasting and it collapses well with good breaking. The test and measurement of blasting vibrating velocity was carried out during blasting and the measuring results are much less than critical values specified by Safety Regulations for Blasting. The study shows that gap form, gap size and gap angle are the key factors to cool tower collapse and will give beneficial references to related theoretical study and field application.展开更多
In order to obtain a basic understanding of the unwanted distortions in the pipe wall during the press cutting process, the deformation of a thin-walled round pipe to form a curvilinear end was numerically and experim...In order to obtain a basic understanding of the unwanted distortions in the pipe wall during the press cutting process, the deformation of a thin-walled round pipe to form a curvilinear end was numerically and experimentally studied. Vector analysis was used to study the relationship between the punch shape and the collapse of the cut-end. Stamping experiments on AISI 1020 steel pipe were conducted using different angles a and β defining the shape of the punch. The elasto-plastic finite element method that allows consideration of a ductile fracture was also employed to study the process. The results show that the deformation of the pipe end after press cutting is inβuenced mostly by the shape of the punch. A satisfactory quality of the curvilinear end of the pipe can be obtained if the appropriate geometric parameters of the punch are chosen. The pipe-wall collapse in the upper part of the section is decreased when a and β increase. The recommended values for a and β lie within 30°-50°. The hole on the underside of the punch has less inβuence on the quality of the cut-end, and the wall distortion and the generation of burr on the cut-end can be satisfactorily simulated using the fracture criterion of Brozzo or the normalized criterion of Cockcroft and Latham.展开更多
文摘Based on blasting demolition of high thin-wall hyperbolic reinforced concrete cool tower, by virtue of engineering practice of blasting the tube concrete structures, the analysis and research were made on the mechanism of cool tower collapse through selecting blasting parameters and selecting gap form, gap size and gap angle. The cool tower was twisted, collapsed directionally and broken well according to the design requirements. The expected results and purposes of blasting were obtained with no back blow, total blasted pile approximates to 4 - 5 m, no occurrence of flying stones and no damage to fixed buildings and equipment, the large-sized hyperbolic thin-wall reinforced concrete cool towers are twisted during blasting and it collapses well with good breaking. The test and measurement of blasting vibrating velocity was carried out during blasting and the measuring results are much less than critical values specified by Safety Regulations for Blasting. The study shows that gap form, gap size and gap angle are the key factors to cool tower collapse and will give beneficial references to related theoretical study and field application.
基金Project(CDJZR10110029)supported by the Fundamental Research Funds for the Central Universities in China
文摘In order to obtain a basic understanding of the unwanted distortions in the pipe wall during the press cutting process, the deformation of a thin-walled round pipe to form a curvilinear end was numerically and experimentally studied. Vector analysis was used to study the relationship between the punch shape and the collapse of the cut-end. Stamping experiments on AISI 1020 steel pipe were conducted using different angles a and β defining the shape of the punch. The elasto-plastic finite element method that allows consideration of a ductile fracture was also employed to study the process. The results show that the deformation of the pipe end after press cutting is inβuenced mostly by the shape of the punch. A satisfactory quality of the curvilinear end of the pipe can be obtained if the appropriate geometric parameters of the punch are chosen. The pipe-wall collapse in the upper part of the section is decreased when a and β increase. The recommended values for a and β lie within 30°-50°. The hole on the underside of the punch has less inβuence on the quality of the cut-end, and the wall distortion and the generation of burr on the cut-end can be satisfactorily simulated using the fracture criterion of Brozzo or the normalized criterion of Cockcroft and Latham.
