箱形渡槽冬季输水工况温度应用和表面保温研究

发布时间：2018-04-22 04:16

本文选题：箱形渡槽 + 冬季输水　；参考：《兰州交通大学》2014年硕士论文

【摘要】：我国水资源时空分布不均且人均水量不足，这导致我国部分地区水资源严重短缺。为了解决我国水资源分布不均匀与供水需求不完全适应的问题，我国修建了一系列跨地区、跨流域、长距离的水资源调配工程。在这些大型输水工程中，渡槽是应用较广的渠系输水建筑物之一。引洮工程位于甘肃省寒冷地区，是甘肃省规划建设的大型跨越流域调水工程。但由于两条供水管线末端均不具备建设大型调蓄设施的工程条件，只能通过延长总干渠供水时间来解决调蓄不足的问题，因此需要考虑冬季输水，保证引水工程在低温环境下的安全运行。所以对北方冬季寒冷地区箱形渡槽的温度效应研究具有非常重要的意义。本文以引洮工程柳林沟箱形渡槽为例，采用有限元软件ANSYS对箱形渡槽在冬季输水工况下的温度场、温度应力和表面保温进行了研究分析。首先，以冬季1月份某天夜间的气温变化为边界条件，采用有限元软件计算在无保温措施下渡槽的温度场和温度应力。通过计算结果可知：当箱形渡槽直接裸露在低温中时，槽身外表面温度比较低，而内表面温度相对较高，从而使槽身内形成内高外低的温度分布状态。靠近槽身外表面的温度梯度较大，而靠近槽身内表面的温度梯度小。温差最大时（5:00），在槽身横截面X、Y方向产生的最大拉应力均已超出了混凝土自身的抗拉强度设计值1.43MPa，容易导致槽身表面出现裂缝。其次，对比分析当槽身外铺设聚苯板和聚氨脂保温材料的厚度分别2cm、5cm和8cm时其温度场和温度应力。采用保温材料保温后，能有效的提高槽身外表面的温度，减小了槽身内外表面的温度梯度，，从而有降低槽身的温度拉应力，且其与保温板的厚度成反比。随着保温板厚度的增加，槽身温度拉应力减小的幅度也越小。保温材料的保温效果与其导热系数成反比。最后，将最大温差时，箱形渡槽在稳定温度场和非稳定温度场的温度应力进行对比分析。研究表明：无保温板时渡槽在稳定温度场中的最大拉应力与非稳定温度场中的最大拉应力相差不大。采用聚苯板和聚氨酯保温板后，槽身在稳定温度场和非稳定温度场中的拉应力值变化也很小。本文通过对比冬季输水工况下箱形渡槽在无保温措施和有保温措施、稳定温度场和非稳定温度场这两种情况下的温度场和温度应力，了解了表面保温对渡槽温度场和温度应力的影响效果，得出一些对箱形渡槽的设计和施工有参考价值的结论，为渡槽在冬季输水工况下应采取的保温措施提供理论依据和技术支持，为制定渠体的引水运行方案提供有力的科学依据。
[Abstract]:The water resources in China are unevenly distributed in time and space and lack of water per capita, which leads to the serious shortage of water resources in some areas of China. In order to solve the problem of uneven distribution of water resources and inadequate demand for water supply in China, a series of trans-regional, cross-basin and long-distance water resources allocation projects have been built. In these large-scale water conveyance projects, aqueduct is one of the widely used canal system water conveyance structures. Tao diversion project, located in cold area of Gansu province, is a large-scale water diversion project across river basin. However, since neither of the two water supply pipelines has the engineering conditions for the construction of large-scale regulating and storage facilities, the problem of insufficient regulation and storage can only be solved by extending the water supply time of the main canal, so it is necessary to consider the winter water conveyance. Ensure the safe operation of water diversion project in low temperature environment. So it is of great significance to study the temperature effect of box-shaped aqueduct in cold winter in northern China. Taking the Liulin ditch box aqueduct of Tao diversion Project as an example, the temperature field, temperature stress and surface insulation of the box-shaped aqueduct under winter water conveyance condition are studied and analyzed by finite element software ANSYS. Firstly, the temperature field and stress of the aqueduct are calculated by using finite element software under the boundary condition of the temperature variation on a certain day in January in winter. The results show that when the tank aqueduct is exposed directly to the low temperature, the outer surface temperature of the tank is relatively low, and the inner surface temperature is relatively high, which results in the formation of the internal high and outer low temperature distribution state in the tank body. The temperature gradient near the outer surface of the groove is larger than that near the inner surface of the groove. When the maximum temperature difference is 5: 00, the maximum tensile stress in the cross section XY of the trough has exceeded the design value of the tensile strength of the concrete itself at 1.43MPa, which can easily lead to cracks on the surface of the groove body. Secondly, the temperature field and thermal stress of polystyrene plate and polyurethane insulation material were analyzed when the thickness of polystyrene plate and polyurethane insulation material were 2cm / 5cm and 8cm, respectively. The heat preservation material can effectively increase the temperature of the outer surface of the groove body, reduce the temperature gradient of the inside and outside surface of the groove body, and thus reduce the temperature tensile stress of the groove body, which is inversely proportional to the thickness of the insulation board. With the increase of the thickness of the thermal insulation plate, the temperature tensile stress of the groove body decreases. The thermal insulation effect of the insulation material is inversely proportional to its thermal conductivity. Finally, the temperature stress of the tank aqueduct in the stable and unstable temperature fields is compared with the maximum temperature difference. The results show that the maximum tensile stress of the aqueduct in the stable temperature field is not different from the maximum tensile stress in the unstable temperature field. When polystyrene and polyurethane insulation boards were used, the tensile stress of the tank in the stable and unstable temperature fields also changed very little. In this paper, the temperature field and temperature stress of box aqueduct under winter water conveyance condition are compared under the condition of no heat preservation, stable temperature field and unsteady temperature field. The effect of surface insulation on temperature field and stress of aqueduct is understood, and some conclusions of reference value for the design and construction of box aqueduct are obtained. It provides the theoretical basis and technical support for the insulation measures of aqueduct under the winter water conveyance condition, and provides a powerful scientific basis for drawing up the water diversion operation scheme of the aqueduct.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV672.3

【参考文献】