高温环境沉管隧道管节早龄期温变特性与控制研究

Research on Early-age Temperature Variation Characteristics and Control of Immersed Tube Tunnel Segments in High-temperature Environment

摘要:

针对高温环境沉管隧道管节全断面浇筑混凝土配合比设计、施工工艺及控裂措施可行性等问题，基于管节几何条件开展数值模拟，合理选取管节温度应力敏感部位并考虑2种不同配合比，建立能表征管节温度和热应力特性的足尺模型，采用自动温度监测系统，开展沉管管节现场模拟浇筑试验。系统研究沉管管节早龄期温度分布及其发展特征、近表面温度拉应力、不同配合比对于管段温度及温度拉应力的影响。结果表明，沉管隧道早龄期温度发展呈非线性特征；顶板近表面温降速率及温度拉应力最大。随胶凝材料增加，管段温度升高，但近表面拉应力减小，开裂风险降低。试验数据与研究结果对同类工程具有参考价值。

Abstract:

Aiming at the issues related to the concrete mix design, construction techniques and feasibility of crack control measures for full-section cast-in-place tunnel pipe segments in high-temperature environments, and based on numerical simulation of the pipe segment geometry, the temperature stress-sensitive areas of the pipe segments are reasonably selected, and two different mix ratios are considered. A full-scale model capable of characterizing the temperature and thermal stress characteristics of the pipe segments is established. An automatic temperature monitoring system is used to conduct on-site simulation casting tests of the immersed tube segments. The early-age temperature distribution and its development characteristics, near-surface temperature tensile stress, and the influence of different mix ratios on the temperature and temperature tensile stress of the pipe segments are systematically studied. The results show that the early-age temperature development of the immersed tube tunnel exhibits a nonlinear characteristic. The temperature drop rate and temperature tensile stress near the surface of the top plate are the largest. With the increase of cementitious materials, the temperature of the pipe segments rises, but the tensile stress near the surface decreases, and the risk of cracking reduces. The experimental data and research results have reference value for similar projects.