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新疆三个泉倒虹吸工程总长约10．7km,倒虹吸管最大设计水头约160m,号称“亚洲第一倒虹吸”,其中Ⅲ标段总长约3 2km,为本倒虹吸工程中工作水头最高的标段。本标段倒虹吸管为双排压力钢管布置,压力钢管内径2．70m,钢管壁厚26mm,镇墩间距为100m,最大墩高7．3m,混凝土设计强度C20F200W6,支墩间距6．70～8．30m,最大墩高6．8m,混凝土设计强度C25F200W6,镇、支墩及其他附属工程混凝土总方量约2．4万m~3。本工程位于新疆准噶尔盆地腹地,北面为戈壁滩,南面紧邻中国第二大沙漠古尔班通古特沙漠,气候干旱酷热,施工条件恶劣;倒虹吸管线地下水位高,地下水氯离子含量1120mg/L,硫酸根离子含量3460mg/L,腐蚀性极强,因此对混凝土的外观质量提出了很高的要求,但恶劣的施工条件和气候条件给混凝土工程施工造成了很大的困难。本文根据该工程混凝土外观质量施工控制的实践经验,从模板、涂刷脱模剂到混凝土拌和、运输、浇筑、振捣、养护及局部缺陷的修补等方面总结了具体的控制措施。
Xinjiang Three Springs inverted siphon project total length of about 10.7km, inverted siphon maximum design head of about 160m, known as the “Asia’s first inverted siphon,” where the total length of section III about 32km, the inverted head siphon works highest head segment. The siphon inverted siphon double-pressure pipe arrangement, pressure pipe diameter 2.70m, wall thickness of 26mm, the town pier spacing of 100m, the maximum pier height 7.3m, concrete design strength C20F200W6, pier spacing 6.70 ~ 8 .30m, the maximum pier height of 6.8m, concrete design strength C25F200W6, town, pier and other ancillary works of the total amount of about 24,000 m ~ 3 concrete. The project is located in the hinterland of the Junggar Basin in Xinjiang, with Gobi Beach in the north and the Gurbantunggut Desert in the second desert of China to the south. The climate is very hot and the construction conditions are poor. The groundwater level of the inverted siphon pipeline is high, and the chloride ion content of groundwater is 1120mg / L , Sulfate ion content of 3460mg / L, extremely corrosive, so the appearance of concrete quality put forward very high requirements, but poor construction conditions and climatic conditions to the concrete construction has caused great difficulties. Based on the practical experience of construction quality control of concrete appearance, this paper summarizes the concrete control measures from the template, brushing mold release agent to the concrete mixing, transportation, pouring, vibrating, curing and repair of local defects.