梯形波纹钢明渠抗冻胀性能有限元模拟

Finite-element simulation of anti-frost behavior of trapezoidalcorrugated-steel water channel

为研究冻土环境中的梯形波纹钢明渠抗冻胀性能,建立了可精细模拟土-渠相互作用的实体-壳体三维空间有限元分析模型,提出了同时考虑含水率与温度的冻土弹性模量计算公式。通过考虑土体在不同月份的温度场变化,采用瞬态热传导模拟了实际升温、降温过程中的土-渠相互作用。合理考虑了含水率与温度对冻土弹性模量、冻胀系数、内摩擦角、黏聚力等本构参数的影响,研究了波纹钢明渠变形与应力的变化规律,分析对比了不同的土体类型与初始含水率、地下水埋深、横撑间距与截面尺寸、波纹钢壁厚与卷边宽度对变形和应力的影响。结果表明:波纹钢明渠可承受一定的水平冻胀作用;渠周土体初始含水率及地下水埋深对波纹钢明渠变形与应力的影响显著,当地下水位在波纹钢侧壁埋深的下半部分时尤为明显;为减小渠体变形,可采取在渠顶设置横向支撑、减小侧壁坡度、增大波纹钢壁厚或加宽卷边的措施,相比之下,前两种更为经济且有效,不过横撑规格需满足受压稳定性要求;设置横撑后,卷边可提供一定的侧向刚度;虽然加宽渠顶卷边对减小渠顶的横向变形有一定贡献,但在10~100 mm宽度范围内贡献不大;未设支撑的波纹钢明渠Mises应力整体低于钢材屈服强度,应力较大的部位多见于底边角部和底部位置,侧壁应力水平不高;设置横撑后,波纹钢渠体应力较大的部位由底部转移至侧壁及卷边,尤其在卷边与横撑的连接处,钢材可达到屈服状态。

In order to study the anti-frost behavior of trapezoidal corrugated-steel water channel in frozen soil environment,the three-dimensional solid-shell finite element model was established,which could precisely simulate the interaction between the channel and soil.The prediction formula of elastic modulus of frozen soil was proposed considering the influence of water content and temperature.By considering the change of temperature field in different months,the soil-channel interaction in the actual warming and cooling process was simulated by using transient heat transferring.The deformation and stress of corrugated steel water channel were analyzed by considering the impact of water content and temperature on the constitutive parameters,such as elastic modulus,frost-heaving coefficient,internal fraction angle and cohesive force.The influences of water content,groundwater depth,space and geometry of transverse brace,width of flange slab and thickness of corrugated steel were investigated for the deformation and stress.The results show that the corrugated-steel water channel can be employed to resist horizontal frost-heaving action.The initial water content and depth of groundwater have significant influence on the deformation and stress,especially when the groundwater level locates in the lower part of the side wall of channel.The deformation can be reduced by setting several transverse braces,decreasing the slope of side wall,increasing the thickness,and widening the flange slab,among which the former two approaches are more economic and effective.Yet,the profile of brace should meet the stability requirement.The flange slab can provide some stiffness only when there are braces.Although widening the flange slab can reduce the top transverse deformation,it is minor within 10-100 mm of the width.The Mises stress in the channel is general lower than the yield strength value for the channel without brace,which is remarkable in the corner and bottom,while insignificant in the side wall.By setting the braces,the location of great stress has changed to the connections of flange slab and braces,where the steel can yield.