Model Experimental Study on Relations Between Sinking Resistance and Vibration Acceleration of Steel Cylinders
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摘要: 钢圆筒基础的应用正随着海上工程的发展而不断拓展,而振动沉贯是安装钢圆筒基础的重要方法。为探究钢圆筒基础振沉阻力的变化规律,利用一套自主开发的模型试验系统,对模型箱中的基础模型施加高频振动荷载,在分层土体中开展了一系列不同最大振动加速度下的模型基础振动沉贯试验,研究振动加速度对振沉阻力、超孔隙水压变化规律和振动沉贯速率的影响。通过平板贯入试验测定了静载条件下的筒-土摩擦特征值,并将实测值与现行Mizutani法计算值进行对比。研究发现:系统的最大振动加速度对振动沉贯过程的影响显著;在相同的场地和设备条件下,最大振动加速度越大的工况,振沉速率也越快,振沉阻力相对静压沉贯阻力的降低程度与振动加速度呈正相关,而基于Mizutani方法得到的振沉阻力有大幅度的高估倾向,工程应用中偏于保守。Abstract: The application of steel cylindrical foundations is expanding because of the development of offshore engineering, and vibration penetration is a crucial method for installing these foundations. To investigate the variation pattern of driving resistance in steel cylindrical foundations, a model testing system was employed to subject the foundation model within a model box to high-frequency vibration loading. A series of model foundation vibration penetration tests were conducted in stratified soil under varying maximum vibration accelerations. The study examined the effects of vibration acceleration on driving resistance, excess pore pressure variation, and vibration penetration rate. Through plate penetration tests, the static friction characteristics between the cylinder and soil were determined. A comparison was made between the current Mizutani method and actual measurements. The research findings highlighted the significant impact of the maximum vibration acceleration of the system on the vibration penetration process. Under identical site and equipment conditions, scenarios with higher maximum vibration acceleration exhibited faster vibration penetration rates. The driving resistance, relative to static penetration resistance, demonstrated a notable reduction that was positively correlated with vibration acceleration. Notably, driving resistance estimated through the Mizutani method displayed a substantial tendency to be overestimated, leading to conservatism in engineering applications.
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