The Feasibility Analysis And Calculation Of River Ice Thermal Expansion Pressure On Riversides

The thermal expansion stress of ice is one of the dominant loads exerted on hydraulic structures in ice-covered period, which greatly influences the normal operations of the establishments of water conservancy and transportation engineering. To describe the variation of ice thermal expansion stress, both exact description of temperature variation in ice and characteristics of thermal expansion stress itself are needed. According to these two aspects, in the present paper, the data of ice temperature and ice thickness measured in Fenhe River, Taiyuan are firstly analyzed to get the characteristics of ice temperature field. Then through examining the common between the generation process of thermal expansion stress and the uniaxial compression test of ice with constant strain rate, the stress-strain curve under low strain rate is simplified to a linear form from zero to maximum. Also the ice mechanics parameters obtained under such conditions are employed to calculate ice thermal expansion stress.Combing with ice conductivity coefficient revised from measured ice temperature, ANSYS software is used to simulate the variation of ice temperature field from AM8 Jan 28 to AM8 Jan 29. Such simulation is divided into 24 load steps and the results agree well with the measured data.From the first load step, thermal expansion stress generated by temperature difference was calculated and considered as the initial stress to analyze the stress variation in the next load step. In terms of in-situ ice conditions, the length and height of the ice model are set to equal to river width and ice thickness, respectively. It is a kind of plane strain problem because the river length is far more than its width so that the width of the model is set to be 1m. A same temperature filed is used to simulate thermal expansion stress under fixed vertical constraint and slope constraint, and the maximal increment of the thermal expansion stress in both calculations are 0.126MPa and O.lMPa respectively, which are close to the maximal increment of ice pressure of 0.133MPa under general conditions deduced from 6 years' measurement data in the Shandian reservoir. The results also indicate the feasibility of the model.