红谷沉管隧道管节大体积混凝土温控与防裂技术

Temperature Control and Crack Prevention Technologies for Segment Concrete of Honggu Immersed Tunnel

红谷双向6车道沉管隧道管节具有横断面尺寸大且结构形式复杂、一次浇筑混凝土体量大、内外温差及温度应力大和防渗抗裂性能要求高的特点。针对这些特点首先通过水化放热性能试验和小圆环开裂试验优选了胶凝材料体系,进而通过力学性能、耐久性能及抗渗性能试验确定了低热低收缩的混凝土配合比,然后开展现浇试块和管段的温度测试,分析大体积混凝土内温度变化规律和冷却水管的降温作用,并结合温控测试与信息化施工技术指导了后续管段预制中冷却水管的布置及相关温控防裂措施的动态部署。最后结合试验分析结果与现场施工环境,形成了管节混凝土入模温度控制、分段分次分节浇筑和快插慢拔捣固工艺、循环冷却水管通水时间和管节拆模时间控制、管节各部位针对性养护措施等贯穿管节预制全过程的防裂技术,确保了沉管管节大体积混凝土的防裂抗渗性能。

The double-line 6-lane section, complex structure, mass segment of Honggu Immersed Tunnel casting concrete, difference between has many characteristics, such as large cross- inner and outer temperatures and temperature stresses and high anti-seepage and crack prevention performances. The hydration heat and small circle cracking test are carried out so as to select cementing materials. The mixing proportion of concrete is determined by mechanical property test, durability test and impermeability performance test. The cast-in-situ test block and temperature test are carried out. The internal temperature variation rules of concrete and effect of cooling pipe are analyzed. The arrangement of cooling pipes during segment prefabrication and relevant temperature control and crack prevention technologies are presented according to temperature control and informatized construction. A series of technologies have been adopted, i. e. concrete temperature control technology, concrete casting technology, time control of cooling pipe and mould dismantling and segment maintaining technology.