作用于防波堤上波浪荷载的离心机模拟

随着港口码头向深水大吨位化的发展,新扩建防波堤逐渐向深水区延伸,防波堤受到的波浪荷载强度越来越高,当堤基位于海底软黏土层上时,由于地基承载力低,往往考虑轻型防波堤结构,在某一防波堤延伸段工程中就推出了薄壁箱筒型基础防波堤新结构。然而,这类轻型防波堤能否经得住设计波浪荷载的作用以及它的性状为工程师所关注,故希望通过土工离心模型试验,在高速旋转的离心力场中模拟作用于防波堤结构上波浪荷载作用,观察其动态反应特性。根据电磁激励器原理研制开发了一套非接触式循环波浪荷载模拟器系统,能提供不同频率、幅值高达1200 N的不对称周期性往复荷载,满足了波浪荷载模拟需要。文中随后介绍了该装置在箱筒型基础防波堤结构与地基的波浪荷载作用试验中的应用,试验测量了防波堤结构的水平变位、沉降和倾斜以及地基中孔隙水压力等性状反应,基于模型试验结果,探讨了波浪荷载作用下箱筒型基础防波堤的破坏模式,结果发现,主要破坏模式为防波堤倾斜过度而失稳或水平变位超出容许值而发生侧向滑动破坏。

Centrifugal simulation of wave loading on a cylindrical breakwater

Cylindrical breakwater is a new type of deep-water breakwater, which is proposed to be constructed on soft ground under severe wave loading. As it is not long before the trial section is built, no severe storm has been encountered till now. Therefore, a specific subject study on the cylindrical breakwater by centrifugal model tests is carried out to investigate the response of the cylindrical breakwater subject to the hypothesized wave load in the design. A specific in-flight simulator is developed to create the cyclic action of severe wave force at the appointed frequency. The response of cylindrical breakwater is depicted in terms of the horizontal, vertical and tilt displacements as well as the excess pore water pressure in the soft ground. The effect of height of lower cylinders and ballasting weight in upper cylinders are studied on working performance. Two main modes of failure are finally proposed in the design for the cylindrical breakwater, that is, the lateral translational sliding failure due to short height of lower cylinders and the overturning failure of excessive tilt displacement due to sustaining wave load with long duration.