Modular Construction Method for Circular Shaft Steel Pipe Frame

Literature Overview

This paper by Zhao Yubi, Zhou Xiaojun, and Mao Lulu from the School of Civil Engineering at Southwest Jiaotong University, published in 2014 in Railway Construction, presents an innovative modular construction method for steel pipe frames used in circular shafts during tunnel construction. The study is based on the construction of a water-bottom shield tunnel launching shaft and receiving shaft in Jiangmen, Guangdong Province, China. The work addresses practical problems encountered during the use of traditional bowl-lock steel pipe scaffolding for formwork support in circular shaft construction.

Problem Identification and Analysis

The traditional approach of using bowl-lock steel pipe scaffolding to erect满堂支架 (full-hall scaffolding) for formwork support in circular shafts was found to have several deficiencies. These included inefficient assembly and disassembly procedures, difficulty in achieving precise circular geometry with straight pipe segments, inadequate adaptability to varying shaft diameters, and excessive material waste due to the inability to reuse components across different projects. The authors systematically analyzed these problems and identified the root causes as the inherent limitations of non-modular construction approaches in the context of repetitive circular shaft construction.

Modular Construction Method Design

The proposed modular construction method introduces standardized steel pipe frame modules designed specifically for circular shaft applications. The key features of this approach include:

The paper provides detailed design drawings for the individual modules, enabling direct application in construction projects. The modular design philosophy aligns with lean construction principles by minimizing waste, reducing labor time, and improving construction quality through standardization.

Engineering Practice and Implementation

The implementation of this modular method at the Jiangmen water-bottom shield tunnel project demonstrated significant improvements in construction efficiency. The modular approach reduced the time required for formwork support assembly and disassembly, which is particularly important in water-bottom tunnel construction where schedule compression is critical due to environmental and safety constraints. The standardized modules also improved the geometric accuracy of the shaft walls, leading to better fit-up with subsequent tunnel lining segments.

From a welding and fabrication standpoint, the modular approach shifts welding operations from the construction site to a controlled fabrication environment, where quality control measures can be more rigorously applied. This includes proper welding procedure qualification, visual and non-destructive testing of welds, and controlled welding sequence planning to minimize residual stresses and distortions in the fabricated modules.

Study Insights and Broader Implications

The modular construction method proposed in this paper exemplifies the application of prefabrication and standardization principles to steel pipe frame construction, a concept that has broad applicability across the construction industry. For engineers involved in tunnel and shaft construction, this work provides a practical framework for evaluating the benefits of modular approaches versus traditional site-assembled scaffolding. The design drawings provided in the paper offer a starting point for adaptation to different shaft diameters and structural requirements. The key insight is that standardization and modularity not only improve construction efficiency but also enhance quality consistency and safety performance, making them worthwhile investments in modern infrastructure projects.