摘要
针对全断面整体式沉管隧道后浇带的体积变形调控问题,分析了CaO膨胀剂和不同活性MgO膨胀剂(90 s、120 s、200 s)的膨胀特性及其对补偿收缩性能的影响规律,并探讨了钙镁复合膨胀剂的比例优化及其在实际工程中的应用效果。结果表明:CaO膨胀剂在早期膨胀速率快,60 d膨胀量为初始3 d的1.45倍,但后期膨胀效果有限;MgO膨胀剂膨胀过程平缓,低活性MgO(200 s)在90 d后仍保持膨胀增长,180 d膨胀量较初期增长6.6倍。通过调整CaO与MgO的比例,可实现早期膨胀与后期补偿的协同作用,满足沉管后浇带全过程裂缝控制的需求。此外,钙镁复合膨胀剂对后浇带混凝土膨胀性能的改善显著,其限制膨胀率在180 d内维持稳定增长,膨胀指数趋于1,体现出良好的膨胀均匀性和收缩补偿性能。通过现场应变和变形监测,证实钙镁复合膨胀剂对沉管隧道后浇带混凝土的体积变形控制和结构稳定性。研究为沉管隧道后浇带混凝土的体积变形调控提供了重要的理论支持和技术参考。
It addresses the volume deformation control of post-cast zones in fully integrated immersed tunnels,analyzing the expansive properties of CaO expansive agents and MgO expansive agents with varying activities(90 s,120 s,200 s)and their effects on shrinkage compensation.The optimal proportion of calcium-magnesium composite expansive agents and their application effectiveness in engineering scenarios were also investigated.The results indicate that the CaO expansive agent exhibits a rapid early-stage expansion rate,with its 60 d expansion amount reaching 1.45 times that of the initial 3 d,but its long-term effect is limited.MgO expansive agents demonstrate a more gradual expansion process,with low-activity MgO(200 s)maintaining growth beyond 90 d and its 180 d expansion amount increasing by 6.6 times compared to the initial value.By adjusting the CaO-to-MgO ratio,a synergistic effect of early-stage expansion and long-term compensation can be achieved,meeting the crack control requirements throughout the entire process of post-cast zones in immersed tunnels.Furthermore,calcium-magnesium composite expansive agents significantly improve the expansion performance of post-cast concrete,with their restrained expansion rate maintaining stable growth within 180 d and the expansion index approaching 1,reflecting excellent uniformity and shrinkage compensation performance.The volumetric deformation control and structural stability of calcium-magnesium composite expanders on concrete in the back casting zone of immersed tube tunnels were confirmed by on-site strain and deformation monitoring.It provides essential theoretical support and technical references for volume deformation control of post-cast concrete in immersed tunnels.
作者
马亿光明
朱成
高英力
MA Yiguangming;ZHU Cheng;GAO Yingli(The Second Engineering Company of CCCC Fourth Harbor Engineering Co.,Ltd.,Guangdong 510230,China;Changsha University of Science and Technology,Changsha 410114,China)
出处
《混凝土》
北大核心
2025年第6期197-203,共7页
Concrete
基金
国家自然科学基金(52278239)
半潜驳运输大型构件关键技术研究(CCCC4.2-JSZX-2024-005)。
关键词
Mg
O膨胀剂
CaO膨胀剂
沉管隧道
后浇带
膨胀特性
收缩补偿
MgO expansive agent
CaO expansive agent
immersed tunnel
post-cast zone
expansive properties
shrinkage compensation
