轨道交通工程侧墙大体积混凝土裂缝控制技术

Crack control technology of side wall mass concrete in rail transit engineering

为减少轨道交通工程车站侧墙大体积混凝土的开裂,通过配合比的优化设计、侧墙试验段分段的开裂风险评估及混凝土的浇筑、振捣、拆模与养护控制,确定引起侧墙混凝土开裂的主要因素是混凝土的外约束作用。计算结果表明,侧墙分段长度宜为16 m;试验段的温度、应变、力学性能、裂缝情况对比结果表明,车站侧墙大体积混凝土应保温保湿养护至14 d龄期;氧化钙类抗裂剂在7~28 d内仅能补偿约27%的后期收缩,建议使用后期收缩补偿能力较强的氧化镁类抗裂剂。

In order to reduce cracking of the station side wall mass concrete in rail transit engineering,through the optimization design of mixture ratio,cracking risk assessment of the side wall test section and concrete pouring,vibrating,dismantle and maintenance control,the main factor causing side wall concrete cracking is concrete outside constraints was determined.The calculation results show that the length of side wall segmenting should be 16 m;the comparison results of temperature,strain,mechanical properties and fracture in the test section show that the station side wall mass concrete should be insulated moisture curing age to 14 d,CaO anti-cracking agents can only compensate for about 27%the late shrinkage within 7~28 d,so it is recommended to use MgO anti-cracking agents with strong ability to compensate the late shrinkage.