After duct segments are demoulded, quite a few circumferential bubbles tend to occur on both sides of them, which affect not only their appearance quality but also their compressive strength and impervious performance to a certain extent. Therefore,it is highly advisable that the bubbles be completely prevented, or, at least, they be minimized. With production practice of the pre-cast duct segments for the shield section of the 1st-term project of Line Two of the rail transit in Taiyuan as a practical example, the causes of the circumferential bubbles on both sides of the duct segments are analyzed, as a result of which it is found that the structure of the mould, the slump of the concrete, the ways of distributing materials and some others all may result in bubbles. Aiming at solving the specific problems, some targeted control measures are put forward in the paper, which result in very good effects. The paper may serve as a certain reference for the control of the appearance quality in pre-casting concrete duct segments for lining in the future.%管片脱模后易在环向两侧面生成较多的气泡,不但影响外观质量,对其抗压强度和抗渗性能也有一定的影响,因此,应尽量地杜绝气泡、将其减少到最低限度.结合太原轨道交通2号线一期工程盾构区间预制管片的生产实践,对管片环向两侧面产生气泡的问题进行原因分析,认为模具结构、混凝土坍落度、布料方式等均为气泡诱发因素;针对具体情况提出了相应的控制措施,取得了较好的效果.为今后预制混凝土衬砌管片外观质量的控制提供一定的借鉴.
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