双护盾TBM掘进施工管片内表面裂缝成因分析

在某双护盾TBM隧洞施工过程中，侧管片内表面连续出现了贯穿管片宽度的裂缝。通过对施工现场详细观察，对裂缝的分布位置、数量、缝宽进行统计分析；结合裂缝观察方式、裂缝性状与TBM操作特点、围岩状况、地下水状况、管片结构、回填灌浆等情况，对裂缝成因进行了探讨和研究。认为TBM在软质地层掘进过程中主推油缸强行牵引及尾盾钢板约束是造成管片内表面裂缝的主要原因，最后，提出了降低或减少裂缝产生的建议与措施。

An Analysis on Causes for Cracks on the Inner Surface of Segments of Tunnel Bored by Double Shield Tunnel Boring Machine

During the construction of a tunnel bored by a double shield tunnel boring machine (TBM), many long cracks were found on the inner surface of the side segments. The positions, quantities and widths of the cracks are summarized after field investigations, and the causes for the cracks are analyzed in terms of TBM operation, rock mass conditions, ground water conditions, segment structures and backfilling grouting conditions. It is concluded that the pulling of the thrust cylinders and the constraint of the steel shell of the shield tail are the main causes for the cracks on the inner surface of the segments. Finally, countermeasures to minimize the cracks are proposed.