渡槽壁板温度应力的仿真与试验研究

Simulation and Experimental Study of Temperature Stress of Aqueduct Wall Plate

以大型渡槽壁板偶遇气温骤然下降时所受温度载荷为基础,开展了混凝土板上表面急剧降温时温度自约束应力测试分析,测定了在不同降温速率时混凝土板上下表面温度差及降温速率为10℃/h时在1 h时刻的混凝土板表面温度自约束主应力,通过对比有限元仿真混凝土瞬态温度应力数值与试验测试数据,验证了有限元建模的准确性。在此基础上,分析了降温速率对渡槽瞬态温度场和应力场的影响,探讨了不同保温材料对渡槽表面温度与应力场的影响。结果表明,随着环境气温下降速率的增大,渡槽表面的温度拉应力将以更快的速度增加;当U型渡槽采用2 mm厚度聚氨酯、聚苯乙烯板和玻化微珠保温材料后,与无保温措施渡槽外表面温度应力相比,渡槽外表面温度拉应力分别减少83%、80%、68%。综合考虑成本与施工技术,玻化微珠保温材料较适合作为渡槽外表面的保温隔热材料。

Based on the temperature load on the wall slab of a large aqueduct when the temperature suddenly drops,the temperature self-confinement stress of the upper surface of the concrete slab was tested and analyzed.The temperature difference between upper and lower surfaces of concrete slabs at different cooling rates and the self-constrained principal stress of concrete slab surface temperature at 1 h at a cooling rate of 10℃/h were measured.The accuracy of finite element modeling was verified by comparing the numerical value of concrete transient temperature stress simulated by finite element method with the experimental test data.On this basis,the influence of cooling rate on transient temperature and stress field of aqueduct was analyzed.The impact of different insulation materials on surface temperature and stress field of aqueduct was discussed.The results show that the temperature tensile stress on the aqueduct surface will increase at a faster rate with the increase of the ambient temperature decreasing rate.Compared with the external surface temperature stress of the aqueduct without insulation measures,the tensile stress of the external surface temperature of the U-shaped aqueduct was reduced by 83%,80%and 68%,respectively,when the polyurethane,polystyrene board and vitrified microbeads with 2mm thickness were adopted.Considering the cost and construction technology,vitrified microbead insulation materials are more suitable as thermal insulation materials on the outer surface of aqueducts.