输水工程埋地钢管变形影响因素及可靠度研究

On the Influencing Factors and Reliability of the Deformation of Buried Steel Pipes in Water Conveyance Project

针对埋地钢管变形影响因素复杂的特点,基于爱荷华公式计算表明,钢管的最大允许埋深与管侧土综合变形模量Ed和D/t有关,Ed越高,D/t越小,允许埋深越大;基于蒙特卡洛方法对钢管变形进行可靠度分析表明:环变形限值为3%时,埋深在3 m以下,钢管刚度基本都符合要求。水重作用下钢管变形会加大,其增幅效果与D/H成线性关系,但其影响随着钢管埋深的增加而降低。水压作用下,钢管变形会大幅度的复圆,水压越大,复圆效果越明显,但高Ed的土体明显约束复圆效果。钢管的变形失效概率随着埋深的增加而加大。

The deformation of buried steel pipes is affected by various factors.Calculation results based on the Iowa formula show that the maximum allowable cover depth of the buried steel pipes is related to the modulus of soil reaction(Ed)and the pipe diameter-thickness ratio(D/t).The higher the(Ed)value and the smaller the(D/t)value,the bigger the allowable cover depth.Reliability analysis of the pipe deformation based on the Monte Carlo simulation shows that for steel pipes with different elastic modulus and the cover depth of less than 3 m,their deformation can meet the requirements with the ring deformation limitation of 3%.Under the action of water weight,the deformation of steel pipes will increase,and the increase effect is linear with(D/H)but decreases with the increase of the cover depth.Under the action of water pressure,the deformation of steel pipes will be greatly rounded.The greater the water pressure,the more obvious the rounding effect.While the soil with higher(Ed)value will largely restrict the rounding effect.The deformation failure probability of steel pipes will increase with the increase of the cover depth.