TBM Crossing of Metro Station Using Semi-Ring Support

Summary In this paper, a novel method based on a semi-ring support has been developed and proposed to facilitate TBM passing the station and restarting the excavation. The results show that the proposed method can be safely used. Introduction Crossing of station is one of the most challenging problems in construction of metro lines. Given the difficulties and problems of using the push frame in the TBM passing station and restarting excavation, this study presents a method based on the use of segmental rings that has been developed for use in underground stations. Methodology and Approaches In this method, in order to create a support for applying the force of TBM thrust, a different pattern of the installation of the incomplete rings has been used so that in addition to utilizing the advantages of using the semi-ring support in such a way that any complete ring is not installed in the space of the station. The proposed pattern is such that three floor segments are used to a distance of about 5 to 6 rings to the end of station; so that TBM will pass through the length of the station. Thereafter, in a few rings, the number of segments increases to 4 and then 5 segments per ring until the cutter head reaches the end of the station. From this stage, the tunnel excavation continues with the installation of the semi-rings of 5 and 6 segments, until the boring machine is completely inserted into the tunnel so that the first complete ring is installed at the beginning of the tunnel. Results and Conclusions The results show that excavation can begin using the 5 and 6 segments, but semi-ring of 6 segments is somewhat superior to 5 segments. The proposed model has been evaluated at some stations of line 6 of Tehran metro and the results show that, in addition to the effectiveness of this method, any over-the-counter deviation has not occurred. Therefore, the proposed method can be safely used.