冲击映像法在深中通道沉管隧道钢壳混凝土界面脱空检测的应用研究

Application of Impact Imaging Method in Void Detection of a Steel Shell Concrete Interface in Shenzhen-Zhongshan Link Immersed Tunnel

深中通道海底隧道的沉管结构是国内首次大规模采用的钢壳混凝土“三明治”沉管结构。这种新型结构形式复杂,自密实混凝土在浇筑过程中易在钢板与混凝土交界面形成脱空缺陷,局部脱空导致抗压强度降低,影响结构的整体安全。为实现钢壳混凝土脱空缺陷的快速、准确检测,以深中通道海底沉管隧道为研究背景,基于冲击映像法开展大型沉管隧道钢壳混凝土脱空质量检测方法研究。首先,通过研究近源波场响应特性的变化规律,研发包括设备、软件及模型在内的钢壳混凝土脱空检测技术。然后,以此为基础,提出钢壳混凝土脱空质量评价指标。最后,通过足尺模型试验对方法的效果进行验证,经验证,检测结果的准确率为91%。试验结果表明:采用冲击映像法能够准确描述钢壳混凝土病害分布、定量评价脱空状况,为深中通道高质量建设和结构优化提供技术支撑。

The Shenzhen-Zhongshan link immersed tunnel first adopts steel shell concrete structure on a large scale in China. The new structural type is complex, voids easily form at the interface of steel plate and coagulation during selfcompacting concrete pouring, and the local void will lead to the reduction of compressive strength and further affects the overall safety of the structure. A case study is conducted on the Shenzhen-Zhongshan link immersed tunnel to realize the rapid and accurate detection of steel shell concrete void defects. Research on the steel shell concrete void quality detection method for a large immersed tunnel is conducted based on the impact imaging method. First, examining the variation law of near-source wave field response characteristics, the steel shell concrete void detection technology,including equipment, software, and model, is developed. Second, the evaluation index of steel shell concrete void quality is proposed on this basis. Finally, the effect of the method is validated by a full-scale model test, and the detection result′s accuracy reaches 91%. The result shows that the impact imaging method can accurately describe the void distribution of steel shell concrete and quantitatively evaluate the void conditions, which can provide technical support for the high-quality construction and structural optimization of the Shenzhen-Zhongshan link.