Study On The Control Mechanism Of Snow Cover Levels On The Intraction Processes Of Ice Sheets And Conical Structures

Many platforms have been founded in cold regions for the exploitation of naturalresources. Installing ice-breaking cones on platforms can reduce the ice force on thesestructures effectively. This method has been widely used in the designs of ice-resistingstructures. It’s observed that the snow cover will influence the interactions betweenthe ice sheets and the conical structures in field observations. However, this problemhas not been researched for the limitation of the field observation technology andmodel test technology.The model tests of the interactions between the ice sheets and the conicalstructures have been developed in this paper. It’s the first time to produce the modelice sheet with snow cover in the world. The interactions between different model icesheets with snow cover and one model cone were simulated in the tests. The modelcone’s geometric parameter kept invariable(the cone angle was60°, and the conediameter on the water plane was60cm). The tests simulated two kinds of D/hi(theratio of the cone diameter on the water plane and the ice thickness), five kinds of icevelocities and three types of snow(sinter snow, fresh snow, and layer snow). Threekinds of snow thickness were simulated in each type of snow cover. One hundredgroups of the tests were performed including the comparative tests of the ice sheetswithout snow cover. The influences of the snow cover level on the ice rubble sizes,ice rubble pile volumes, ice force amplitudes and periods have been researched in thetests. It was found that the steady ice rubble pile can’t form unless the ratio of D/hiwas high and the snow cover existed.The snow cover could reduce the ice rubble size effectively, and increase thenon-simultaneity in the failure process. Several kinds of the ice rubble pile shapeswould be formed in different ratios of D/hiand snow cover conditions. The unstableice rubble pile was formed of multilayer ice rubble on the conical surface when theratio of D/hiwas low and snow cover existed. The steady ice rubble pile was formedbetween the cone and the ice sheet when the ratio of D/hiwas high and the snowcover existed.The ice force on the cone would be influenced by different snow coverconditions. The sinter snow cover would increase the ice strength, and then increase the ice force on the cone. The fresh snow and layer snow cover would decrease the icestrength, and then decrease the ice force. Based on the model tests, the reductioncoefficients of ice strength, ice thickness and ice sheet failure mode were introducedto Ralston model to consider the snow cover effect. The modified formula wasconfirmed by the comparison between the calculated results and the test data.The snow cover level affected the ice force period obviously. The snow covercondition couldn’t influence the ice force period remarkably when the ratio of D/hiwas low. When the ratio of D/hiwas high, the snow cover condition would influencethe failure periods of far circumferential cracks, and increase the non-simultaneity inthe failure process. At the same time, the clear process of the ice pile increased the iceforce in high frequency, and the periodicity of the clear process influenced the iceforce period obviously.