This paper studies a consecutive excavation technique to enhance the shield TBM advance rate. Helical type segments are considered for one solution for the continuous excavation of shield TBM. When using helical segments, the thrust jacks compress on the inclined side wall of the segments. The inclined contact can induce the side force and bending moment of the hydraulic cylinder, which can arouse oil leak or plastic deformation of rod and cylinder parts. The study examined the buckling reliability of thrust jack against to the compressive force on the inclined surface of helical segment. A numerical simulation was conducted for analyzing the structural stability. The reliability testing code was established and the testing specimen of jack and loading jigs were manufactured for the compression test of the jack. After the compression test was conducted, the testing results are summarized for validation.
The shield TBMs (tunnel boring machine) applications are increased in Korean tunneling sites. A research project is ongoing to enhance the TBM advance rate by reducing the non-operation time during the segment installation. Helical type segment (Rostami, et al., 2019) is considered for one solution for the continuous excavation of shield TBM.
Generally, TBM thrust jacks have the role to advance the cutter head by providing a normal force on to the side wall of segments. If using helical type segments, the TBM thrust jacks have to compress on the inclined wall of the segments because the helical segment has a pitch angle (Figure 1). The inclined contact can induce the side force and bending moment of the hydraulic cylinder, which can arouse oil leak or plastic deformation of rod and cylinder parts. To guarantee the buckling strength of cylinder and seals parts, structural safety has to be precisely examined before the full scale tunneling test (Kongshu et al., 2019).
To investigate the structural stability, a numerical analysis of thrust jack was simulated under normal contact and inclined contact conditions. The stress level of cylinder, ram, frame and pedestal parts were analyzed (Sugimoto et al., 2019). To confirm the reliability of the simulation, a series of compression test was carried out. The testing results were analyzed and the buckling strength and stability of the thrust jack were evaluated.
