The Method of Predicting the Confidence Interval by the Culvert Capacity of Channels at the Design Stage

Abstract

The purpose of the research is to develop a methodology for predicting confidence intervals of functional parameters of main channels at the design stage, taking into account the probability of absolute changes occurring in their hydraulic parameters during construction and operation. In this regard, taking into account that during the construction and operation of main channels, the frequency of absolute changes in the values of the living cross-section area, wetted perimeter, hydraulic radius and bottom slope obeys the normal distribution law, and the channel roughness coefficient is an increasing and arbitrarily variable random variable, the possibility of predicting the probable confidence interval for the channel’s culvert over the period of operation is investigated. For this purpose, the Monte Carlo method and the Excel program were used, and a method for predicting the confidence interval of the design value of the channel flow rate was proposed. The corresponding analyses were carried out according to the design values of hydraulic parameters on the studied sections of the main channels operated in the Republic of Azerbaijan. Assuming that the design value of each hydraulic parameter is an average value, and the mean square deviation is within the probability, the generation of normally distributed random variables is compiled (provided that the channel roughness coefficient is an increasing and arbitrarily variable value in the appropriate limit), and according to the flow formula for a steady uniform movement, the maximum flow rate of the channel is calculated. The confidence interval of the average value of the predicted maximum flow rate is determined and compared with the design value of the maximum flow rate on the studied section of the trunk channel. Based on the proposed method, the effect of influencing the average value of the maximum flow rate was analyzed in the case of the roughness coefficient of the channel remains unchanged, and probabilistic scattering of other hydraulic parameters occurs around the design values, as well as, in general, the corresponding hydraulic parameters are scattered around the design values.