地铁超长侧墙结构混凝土裂缝控制及工程应用

地铁停车场地下侧墙属超长大体积混凝土结构,混凝土施工时具有水化温升高、温降速率大等特点,且受底板和已浇筑侧墙的复杂约束作用,混凝土在降温过程中极易出现早期开裂现象。通过掺入抗裂剂配制具有低水化放热和补偿收缩的侧墙高性能抗裂C35混凝土,以绝热温升和自身体积形变表征混凝土抗裂性能,结果显示:掺入抗裂剂后胶凝材料水化集中放热大幅度缓解,混凝土绝热温升及其早期温升速率明显降低,且混凝土膨胀率增加,自收缩得到有效补偿;应用于地铁超长侧墙结构的混凝土中心温峰为55.8℃,最大温升为23.3℃,侧墙中心厚度方向最大膨胀变形为256×10-6,且拆模后无明显裂缝,为同类超长混凝土结构工程裂缝控制提供参考。

Experimental study on the variation law of coal temperature during excavation in coal mines

By testing the temperature of the coal and the stress of the working surface, we got the variation law of coal temperature and coal stress during the excavation. The result shows that the activities of mining affect the coal temperature, the fluctuation of coal temperature and the coal stress is synchronous. During the smooth change of crustal stress, the coal temperature basically keeps unchanged, when the dynamic phenomenon appears, the coal temperature changes, as well the coal stress. Therefore, we can use the online coal temperature monitoring system to test the coal temperature of the working surface continuously, and it can provide basic information for forecasting coal mine power disaster before it happens.