Field Test And Numerical Simulation Of Roughness Coefficient Of Form Concrete Channel

Because of the cold climate in northern China,rigid material lining channels such as concrete are often subjected to frost heaving damage,which seriously affects the safe operation of the channel and the performance of the project benefits.In order to solve the problem of frost heaving damage of lining channels,many irrigation districts in the north have begun to adopt mold bag concrete lining channels in recent years.Because of the good integrity of the mold bag concrete and the strong ability to resist frost heaving deformation,a good anti-frosting effect is obtained.However,in the current planning and design of the mold bag concrete lining channel,the roughness coefficient is still selected according to experience,which affects the accuracy of the channel engineering cost and the safety of operation management.This paper based on summarizing the structure of the mold bag concrete lining channel,selected four sub-main channels in the Hetao Irrigation District,and carried out the prototype observation test and numerical simulation of the roughness coefficient of the mold bag concrete channel,aiming at the mold bag concrete full-section and composite-section two types of channel lining.The main research results are as follows:(1)Two structural types of mold bag concrete lining channels: the full-section lining channel and the composite-section lining channel was proposed in this paper,the prototype observation experiment of the roughness coefficient of the full-section mold bag concrete lining was respectively carried out in the Yonglan sub-channel(11+814)and the Shiba sub-channel(9+903)in the Inner Mongolia Hetao Irrigation District,and the prototype observation experiment of the composite-section mold bag concrete lining channel was carried out in the Shiba sub-channel(0+200~2+216)and the Jianshe Second sub-channel(1+910~3+040)in Hetao Irrigation District of Inner Mongolia.(2)Established the functional relationship between hydraulic measurement error and channel roughness measurement error in prototype observation,respectively calculated and analyzed the roughness measurement error of the full-section lining channel and the composite-section lining channel of mold bag concrete,and calculated that the maximum measurement errors of the roughness coefficient of the Yonglan sub-channel(full-section),the Shiba sub-channel(full-section),the Shiba sub-channel(composite-section)and the Jianshe Second sub-channel(composite-section)are respectively 6.253%,3.178%,5.0373% and 4.3050%.(3)By combining the section splitting method with the calculation method of the shear stress of the composite-section mold bag concrete channel,the formula for calculating the roughness coefficient of the mold bag concrete composite-section was derived.And compared the experimental observation data with the data calculated from the derived roughness calculation formula of the mold bag concrete composite-section,the maximum relative error between the calculated results and the experimental observations is 8.827%,which indicates that the calculation results are relatively accurate and can meet the practical engineering application.(4)Established a three-dimensional model of open channel flow,used the standard turbulent k-εmodel to close the Reynolds time-average equation,and numerically simulated the water flow in the mold bag concrete lining channel.Compared the experimental observation data with the numerical simulation results,of which the results show that the experimental observation data values are basically consistent with the numerical simulation results,and the maximum error is 2.726%.It is proved that the established three-dimensional mathematical model and its calculation parameters are reasonable and feasible,and it has certain guiding significance for the future research on the hydraulic performance test of the mold bag concrete channel.