Analysis Of The Values Of River Ice Strength And Research On Ice Loads Based On The Unascertained Information Theory In Drift Ice Epoch

Ice flood happened in75%of the regions in China. Many local hydraulic structureswere damaged in different degree. The phenomenon in Inner Mongolia section ofthe Yellow River, the Nen river upstream and the Heilongjiang river upstream areparticularly serious. So carrying out research on the values of ice strength and iceload in drift ice epoch is particularly important.According to the national achievements from the river ice mechanicalproperties and part of ice mechanical properties test data of Heilongjiang Provincein drift ice epoch, we find that ice temperature is always at-2℃～0℃, however,the standard stipulate that the value of ice strength is the one when ice temperatureis0℃. At the same time the standards don’t consider the effect of strain rate andthe errors from measurements and human. In this paper, we analyze the icecompressive strength and bending strength of Heilongjiang Province with themethod of probability theory statistically. To work out the probability distributionof river ice strength in the condition that the strain rates are different and the icetemperature is-2℃～0℃Then the optimal benign of probability distribution isinspected by Monte Carlo simulation method and the hypothesis test method, andthe probability distribution function of river ice compressive strength and bendingstrength are provided. Through the statistical analysis of the ratio of river icecompressive strength and river ice bending strength in the same condition, thepropositional multiple is0.65. Based on reliability theory, this paper analyzes themethod of characteristic value of river ice compressive strength and bendingstrength, and concludes the relationship of river ice strength and reliability level.And take Jiamusi Songhua river highway bridge section as an example for analysis,we find that the error of the calculated value and measured value of ice load is only0.524%when we adopt the value of ice compressive strength on99%reliabilitylevel. Finally, this paper reviews the ice load calculation formula and establishes ageneral model which puts forward the ice load calculation formula based on theunascertained information theory. This mathematical model can give the probablevalues interval of ice load and the relevant subjective credibility by analyzing the examples.This topic puts forward problems of the values of ice strength existing in thestandard and analyzes the values of river ice strength of Heilongjiang region in driftepoch with probability theory and reliability theory,and then summarize the iceload calculation formula and put forward the new formula based on theunascertained information. The research methods and results above can providemore bases and the reference for designers.