Dynamic Response And Safety Evaluation Of Vicinal Pier Subjected To Underwater Blasting Vibration

Structural Response subjected to underwater blasting is quite a complex question. It is not only relevant to explosive mass, distance between structure and explosive center, but also associates with surrounding medium and structural dynamic characteristics. So far the research about this subject almost has been made by experimental observation, and can't be simulated accurately due to lots of influence factors. Restricted by research and analysis methods, domestic study is almost none. Along with underwater blasting widely used in industrial and civil architecture, the significance of structural response analysis subjected to it is much more distinct.This paper relies on rebuilding and extending engineering of Dalian New Port, the nearest 4# pier's possible response was studied. First, the process of underwater blasting was numerically simulated and the blasting acceleration signal was picked up. Then transient analysis, blasting spectrum analysis and safety evaluation of pier (before ageing and after ageing) were performed. At last, some recommendations for safety criterion were proposed. Works and results are mainly as follows.1. The background of rebuilding and extending engineering of Dalian New Port was summarized. Mechanism of underwater blasting action was introduced. The achievements and deficiencies of the numerical simulation were summarized about two aspects: propagation of underwater blasting wave, and its influence on structural dynamic response. Based on the above analysis, the study purpose and meaning of this paper was indicated.2. The simulation of underwater blasting of six cases which have different explosion mass and ground was performed with the aid of LS-DYNA3D. The rules of blasting velocity and acceleration were deduced. Several factors, such as the distance between structure and explosive center, explosive mass and site properties, were also analyzed.3. Transient and spectrum analysis of 4# pier was carried out on the base of the numerical simulation of underwater blasting. The rules of pier's displacement, velocity, acceleration and stress response were deduced. The relationship of blasting response with explosive mass and site properties was also analyzed.4. Material ageing was induced in the transient and spectrum analysis of pier subjected to underwater explosion. Its influence over the response of pier was discussed.5. Safety evaluation of pier was made according to safe criterion of blasting. Comparing to the numerical results, some recommendations were proposed.