输水工程大直径钢管外包混凝土垫层结构研究

Study on the Structure of Large Diameter Steel Pipe Wrapped with Concrete Cushion in Water Conveyance Engineering

为研究输水工程中垫层弹模和厚度对钢管外包混凝土结构应力分布的影响,确定垫层参数的最优取值,以引汉济渭二期输水工程为背景,运用有限元软件,对大直径钢管外包混凝土垫层结构进行分析研究。确定钢管及外包混凝土在垫层不同弹性模量、不同厚度下的应力状态。结果标明:设置垫层后,外包混凝土主应力明显降低,有效改善钢管及外包混凝土的应力分布;随着垫层弹性模量的减小,钢管的等效应力逐渐增加,外包混凝土的主应力逐渐减小;垫层厚度小于20 mm时,外包混凝土最大主应力随垫层厚度增大而减小,厚度大于20 mm时,外包混凝土最大主应力减小情况不显著,垫层最优厚度10~20 mm;垫层弹性模量和厚度同比例时,钢管等效应力和外包混凝土主应力基本不变。研究成果对输水工程中大直径钢管外包混凝土垫层结构选择具有参考意义。

To study the influence of cushion modulus and thickness on the stress distribution of steel pipe encased concrete structures in water conveyance engineering,and determine the optimal values of cushion parameters.This paper takes the second phase of the Hanjiang-to-Weihe River Water Transfers Project as the background,and uses finite element software to analyze and study the structure of large-diameter steel pipe wrapped with concrete cushion layer.Determine the stress state of steel pipes and outer concrete under different elastic modulus and thicknesses of the cushion layer.The results indicate that:after setting the cushion layer,the main stress of the outer concrete is significantly reduced,effectively improving the stress distribution of steel pipes and outer concrete;as the elastic modulus of the cushion layer decreases,the equivalent stress of the steel pipe gradually increases,and the principal stress of the outer concrete gradually decreases;when the thickness of the cushion layer is less than 20 mm,the maximum principal stress of the outer concrete decreases with the increase of the cushion layer thickness.When the thickness is greater than 20 mm,the reduction of the maximum principal stress of the outer concrete is not significant,and the optimal thickness of the cushion layer is 10~20 mm.When comparing the elastic modulus and thickness of the cushion layer,the equivalent stress of the steel pipe and the principal stress of the outer concrete remain basically unchanged.This paper provides reference for the selection of large-diameter steel pipe wrapped concrete cushion structure in water transmission engineering.