摘要
为进一步探明水库大坝现场原位聚氨酯保温层长期服役后的劣化特性,以响洪甸水库大坝为例,选取大坝下游面典型部位开展了保温层各层间粘结性能现场试验,采用扫描电镜对现场取样的聚氨酯试样进行了微观形貌表征分析,测试了导热系数、压缩强度等关键性能指标,计算分析了相应的混凝土保温层表面放热系数。聚氨酯层与混凝土基面的拉伸粘结强度以及聚氨酯的压缩性能均有所下降,且潮湿聚氨酯的下降程度远大于干燥聚氨酯。与初始增设聚氨酯时相比,干燥部位聚氨酯保温层因内部微孔结构老化导致其导热系数有所升高(22.9%),但保温服役状态仍满足原设计要求;含水潮湿部位保温层,其保温服役状态已不满足要求。保温层长期服役过程中聚氨酯微孔结构老化与外界水分入侵的耦合作用显著加剧聚氨酯劣化过程,大幅降低其粘结性、压缩性和保温性。
In order to further explore the degradation characteristics of polyurethane insulation layer after long-term on-situ service of reservoir dams,taking the Xianghongdian Reservoir Dam as an example,field tests were conducted on the bonding performance between different layers of the insulation layer in typical sites of downstream face of dam.Scanning electron mi-croscopy was used to conduct microscopic morphology characterization analysis on polyurethane samples taken from the site.Key performance indicators such as thermal conductivity and compressive strength were tested,and the corresponding surface heat release coefficient of the concrete insulation layer was calculated and analyzed.The results showed that the tensile bond-ing strength between the polyurethane layer and the concrete substrate,as well as the compressive performance of on-site sam-pled polyurethane had decreased.And the declined degree of wet polyurethane was much greater than dry polyurethane.Com-pared with the initial addition of polyurethane,the thermal conductivity of the polyurethane insulation layer in the dry area had increased by 22.9%due to the aging effect of the microporous structure,however the insulation service state still exactly meets the original design requirements.For insulation layers in areas with moisture content,their insulation service status no longer meets the requirements.During the long-term service of the insulation layer,the coupling effect of aging of polyurethane micro-porous structure and external water intrusion will significantly intensify the degradation process of polyurethane,significantly re-ducing its adhesion,compression performance,and insulation performance.
作者
程习华
CHENG Xihua(Anhui Xianghongdian Reservoir Management Office,Lu'an 237000,China)
出处
《江淮水利科技》
2024年第2期7-12,I0001,共7页
Jianghuai Water Resources Science and Technology
关键词
大坝保温
聚氨酯
导热系数
服役状态
dam heating insulation
polyurethane
thermal conductivity
in-service state
