| As the global climate warms,it is becoming increasingly realistic and important toexpand the development of the Arctic shipping lanes.As a new auxiliary ice-breaking method,the high-pressure bubble ice-breaking technology,has the advantages of high efficiency,cleanliness,and a clear directional range of action,which attracts the attention from both domestic and foreign researchers.Based on background,this thesis proposes a high-pressure airgun-bubble ice-breaking method,which aims to enhance the engineering application potential of airgun-bubble ice-breaking technology based on the aforementioned advantages.To address the strong non-linear coupling between airgun bubble,ice,and water in the process of breaking ice,a combination of mechanistic experiments,external field tests,and numerical simulations are used to study the motion law and load characteristics of bubble under complex boundary conditions,and the destruction mode of ice under multiple loads of high-pressure bubblesA laboratory generation method of high-pressure airgun bubbles is proposed to obtain underwater high-pressure bubbles with a directional jet.Due to the lack of experimental methods and data of high-pressure airgun bubbles in China,the experimental method of high-pressure airgun bubbles is introduced,and the ice-breaking mechanism experiment and outer field test platform of high-pressure airgun bubbles are set up,building a foundation for the relevant mechanism experiment and full-scale test.An experimental study on the mechanism of high-pressure airgun bubble was carried out.The motion law and the fluid loading characteristics of high-pressure airgun bubbles in the free field,near the free surface,and far free surface were investigated by changing the boundary conditions.On this basis,rigid wall conditions were added to study the motion law of high-pressure airgun bubbles near the wall and the characteristics of fluid load on the rigid wall under different burst distance conditions.The unique "pear-shaped" shape of the high-pressure airgun bubble and the high-pressure air jet disturbing the flow field and thus the jet stream load generated on the wall were found.In the high-pressure airgun bubble icebreaking mechanism experiments,the dynamicresponse of ice and the damage modes:radial crack mode,radial/circular crack mode and radial crack mode,were investigated under the first shock wave,jet load,secondary shock wave/jet load,and combined bubble load,respectively.The influence of the distance parameter H and the ice thickness parameter T on the ice-breaking results is studied and the distribution pattern of the damage modes is given.In the full-scale test of high-pressure airgun bubble ice breaking,firstly,a high-pressure airgun bubble full-scale test device was developed independently based on the mechanism experimental device,and the full-scale test method was proposed.Besides,the test design was designed for the melt ice period and the freezing period of the Songhua River respectively.Before the full-scale test,the physical and mechanical properties of the river ice of the Songhua River were studied,and the changes in river ice parameters during different periods were analyzed.Based on these studies,the ice-breaking test was carried out,and the maximum ice thickness was up to 0.7m,which verified the engineering application potential of the high-pressure airgun bubble.In the numerical study of high-pressure airgun bubble ice breaking,the high-pressure airgun bubble load was decomposed,and the empirical equation combined with boundary element method were used to simulate the airgun bubble-induced first shock wave and second shock wave/bubble jet load respectively,while the dynamic response of ice was modelled by peridynamics.The zone-step loading method of airgun bubble load was proposed and the numerical model of icebreaking by airgun bubble load was established.Finally,the first radial and circular crack damage mode of ice under airgun bubble load was successfully simulated.The comparison shows that the numerical results were in good agreement with the experimental results. |
