冰对水工结构物作用力的物理模拟—Ⅲ.冰对结构物撞击作用力模拟实例

Physical simulation of ice forces on hydraulic structures-Ⅲ.example of ice impact forces on structures

当流冰质量小,运动速度低时,具有的动能也小,其对结构物的作用形式是撞击,而不是挤压。为了合理设计渤海近岸码头排桩承受的冰力,利用DUT-1模型冰和实验室设备物理模拟水流带动模型冰块以一定速度撞击码头排桩模型,获得作用于一榀码头排桩上单桩或同时作用于群桩上的试验冰力。系列试验结果表明上限冰力值随流冰压缩强度和动能增加而增加,并趋向一定值。通过数学统计拟合,得到作用在单桩上的上限冰力同流冰动能和压缩强度之间的试验关系。该关系将流冰的面积、厚度、密度、运动速度、压缩强度同单桩上的上限冰力结合起来,能够作为流冰对单桩设计冰撞击力的基础,具有普适性意义。此外,结合渤海具体码头工程,用该试验成果评估作用在一榀码头排架单桩上和整体排架结构上的原型冰力。

Ice floe with less mass and lower speed has lower kinetic energy. As it attaches structures, there will be only impact forces rather than crushing forces on the structures. In order to make proper design ice forces on pile structures of wharfs in the coastal area of Bohai Sea, the impact on the piles of a wharf model with a certain floe speed in a water flume was conducted by using DUT-1 model ice floes and laboratory e- quipments. The impact forces on a single pile and piles group were measured. A series of experiments indi- cated the upper limit of ice impact force increases with the rise of ice compressive strength and its kinetic energy, and tends to a certain value. Based on statistic analysis and curve fitting, the relations among the upper limit of ice impact force on a single pile, ice peak compressive strength and its kinetic energy are ob- tained, through which peak compressive strength with the upper limit of ice impact forces is combined with the floe size, thickness, density, velocity. The relations can be considered as the base of design ice force on a single pile, and it is of great significance in ice engineering. In addition, the impact force on an isolated pile and the resultant forces on piles group are evaluated in an element of wharf structure in Bohai Sea, according to the test results.