冬季运行期矩形渡槽温度应力分布规律研究
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摘要
为研究冬季降温运行期矩形渡槽的温度应力分布变化规律,根据热传导理论及水工渡槽的温度边界条件,建立了北方地区某简支封闭矩形渡槽的有限元模型,并对冬季运行期温度应力分布规律进行分析研究。结果显示:渡槽在冬季降温运行时,沿板壁厚度方向的温度梯度外大内小,内外温差为二次曲线分布;温度应力总体呈现外拉内压的分布状态,各板壁的内外表面在不同时刻出现最大压应力和拉应力,同时板壁最大压应力较最大拉应力具有一定的滞后性;板壁及棱角部位的横向与竖向最大拉应力值超出混凝土抗拉强度设计值。可见在设计矩形渡槽时,必须重视环境温度作用对结构的影响,通过配置温度钢筋、施加横向预应力、棱角部位设置倒角和增加表面保温等措施来减小温度应力,增强结构的安全性和耐久性。
In order to study the changing law of the temperature stress distribution of rectangular aqueduct during the operation in winter,the finite element model of a simply supported and closed aqueduct in the northern region is established in accordance with the temperature boundary condition of the aqueduct and the relevant heat transfer theory,and then the law of the temperature stress distribution of the rectangular aqueduct during the operation in winter is studied. The result shows that when the aqueductoperates during temperature drop in winter,the temperature gradient along the direction of the thickness of the slab-wall is large outside and small inside,while the inside and outside temperature difference exhibits a quadratic curve distribution. The temperature stress exhibits a distribution status of tensing outward and compressing inward,at the same time,the maximum compression stress and tensile stress occur at different moments on both the outer surface and the inner surface of all the slab-walls,while the maximum compression stress of the slab-wall has a certain hysteretic nature if compared with that of the maximum tensile stress. Both the transverse and vertical maximum tensile stress values of the slab-wall and the corner exceed the design values of the concrete tensile strength. It can be seen that great attention must be paid on the effect of the ambient temperature on the structure,thus the temperature stress must be decreased through the measures of arranging temperature reinforcement,applying transverse pre-stress,arranging chamfer at corner,increasing surface insulation,etc.,so as to enhance the safety and durability of structure.
In order to study the changing law of the temperature stress distribution of rectangular aqueduct during the operation in winter,the finite element model of a simply supported and closed aqueduct in the northern region is established in accordance with the temperature boundary condition of the aqueduct and the relevant heat transfer theory,and then the law of the temperature stress distribution of the rectangular aqueduct during the operation in winter is studied. The result shows that when the aqueductoperates during temperature drop in winter,the temperature gradient along the direction of the thickness of the slab-wall is large outside and small inside,while the inside and outside temperature difference exhibits a quadratic curve distribution. The temperature stress exhibits a distribution status of tensing outward and compressing inward,at the same time,the maximum compression stress and tensile stress occur at different moments on both the outer surface and the inner surface of all the slab-walls,while the maximum compression stress of the slab-wall has a certain hysteretic nature if compared with that of the maximum tensile stress. Both the transverse and vertical maximum tensile stress values of the slab-wall and the corner exceed the design values of the concrete tensile strength. It can be seen that great attention must be paid on the effect of the ambient temperature on the structure,thus the temperature stress must be decreased through the measures of arranging temperature reinforcement,applying transverse pre-stress,arranging chamfer at corner,increasing surface insulation,etc.,so as to enhance the safety and durability of structure.
引文
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[3]季日臣,严娟,苏小凤.混凝土箱形渡槽日照高温下结构安全研究[J].南水北调与水利科技,2013,11(6):90-92.
[4]李苏航,季日臣,柏文文.渡槽在折线温差分布下的横向温度应力计算[J].水电能源科学,2016,34(12):121-124.
[5]王潘绣,赵海涛.大型U型渡槽正常运行寒潮期仿真分析[J].水电能源科学,2010,28(7):92-94.
[6]宋书卿.特大型空心渡槽运行期温度应力研究[D].武汉:武汉大学,2005.
[7]潘崇仁.克孜河渡槽运行期温度应力耦合分析[J].水利与建筑工程学报,2017,15(5):224-227.
[8]陈武,张东,李双洋,等.引洮工程封闭渡槽输水期间热力耦合分析[J].水利水运工程学报,2012,28(3):20-25.
[9]任德记,张超,王刚,等.预应力矩形渡槽温度应力有限元分析[J].中国农村水利水电,2011(12):111-114.
[10]刘龙.大跨度叠箱渡槽温度场研究[D].北京:北京工业大学,2015.
[11]聂利英,刘明坡,朱倩,等.基于实测的混凝土箱梁底板温度梯度研究[J].重庆交通大学学报(自然科学版),2016,36(10):8-14.
[12]陶翀,谢旭,申永刚,等.基于概率分析的混凝土箱梁温度梯度模式[J].浙江大学学报(工学版),2014,48(8):1354-1361.
[13]薛刚,孟煜童,白纬宇.大跨度混凝土连续箱梁桥运营阶段的温度场分析[J].工程力学,2017,34(S1):116-121.
[14]刘江,刘永健,房建宏,等.高原高寒地区“上”形钢-混凝土组合梁的竖向温度梯度模式[J].交通运输工程学报,2017,17(4):32-44.
[15]朱伯芳.大体积混凝土温度应力与温度控制[M].北京:中国水利水电出版社,2012.
[16]王同生,于子忠.涵闸混凝土的温度应力与温度控制[M].北京:中国环境科学出版社,2010.
[17]凯尔别克.太阳辐射对桥梁结构的影响[M].北京:中国铁道出版社,1981.