基于Midas FEA的箱涵套管加固效果分析

以湖北省某农村公路提档升级项目中箱涵套管加固为工程背景,考虑混凝土的材料非线性,简化填土与箱涵之间的接触非线性,利用Midas FEA建立箱涵套管加固的精细化有限元模型,对比分析了箱涵套管加固前后的受力性能。计算分析表明:箱涵加固后其水平变形、竖向变形分别下降98.21%、96.53%,混凝土的第一主拉应力、第一主压应力最大值分别下降82.09%、94.95%,钢筋的拉应力、压应力最大值分别下降93.26%、85.00%,裂缝宽度最大值一定程度降低,箱涵采用套管加固效果明显;套管加固后,套管内钢筋以及填充区混凝土应力较小,考虑工程经济性,可在规范允许范围内适当降低套管配筋率、选取低强度钢筋、降低填充区混凝土标号,建议在石料充裕时采用片石混凝土代替混凝土。

Reinforcement Effect Analysis of Box Culvert Covering Pipe Based on Midas FEA

With a box culvert covering pipe reinforcement project in a rural highway upgrading project in Hubei Province as the engineering background, considering the material nonlinearity of concrete and simplifying the contact nonlinearity between the fill and the box culvert, Midas FEA was used to establish a refined finite element model of the box culvert covering pipe reinforcement. The mechanical performance of the box culvert covering pipe reinforcement before and after reinforcement was compared and analyzed. The calculation and analysis show that after the box culvert is strengthened, its horizontal deformation and vertical deformation are reduced by 98.21% and 96.53% respectively, the maximum values of the first principal tensile stress and the first principal compressive stress of concrete are reduced by 82.09% and 94.95% respectively, the maximum values of tensile stress and compressive stress of steel bar are reduced by 93.26% and 85.00% respectively, and the maximum crack width is reduced to some extent. The reinforcement effect of box culvert with covering pipe is obvious. After the covering pipe is reinforced, the stress of the steel bars in the covering pipe and the concrete in the filling area is small. Considering the engineering economy, it is advisable to appropriately reduce the casing reinforcement ratio, select low-strength steel bars and reduce the concrete grade in the filling area within the scope permitted by the code. It is suggested to use rubble concrete instead of concrete when there are plenty of stones.