Abstract: Physicomechanical property testing of muck generated from earth pressure balance shield tunneling relies heavily on manual sampling with long cycles and fails to timely reflect construction conditions. To address these challenges, an automated muck state detection method for shield construction sites is proposed. Based on the vane shear test principle, an automated detection device integrating automatic sampling, shear testing, data processing, and automatic muck cleaning is developed. A conversion method between muck shear strength and slump is established based on existing theoretical relationships, and an automated control program is developed for rapid online detection of parameters, including muck shear strength, slump, temperature, and hazardous gas concentration. Field tests were conducted in the shield section between the Anshanxidao Station and the Nanfenglu Station of the Tianjin Metro Line 8. Equipment commissioning and automated process verification were completed, and the relationships between muck state and shield tunneling parameters, such as cutterhead torque and total thrust, were comparatively analyzed under different working conditions. The results are as follows: (1) The device enables automatic sampling and online detection during continuous tunneling, with a single detection cycle of 410－420 s (approximately 20 s for the shear test). (2) Detection of 12 groups of representative field working conditions shows that removing the data from the vane shear plate start and stop stages and averaging data from the stable stage can effectively reduce detection fluctuations and yield stable results. (3) The detected muck slump correlates well with shield tunneling parameters. As slump increases, cutterhead torque and total thrust generally decrease, with cutterhead torque more sensitive to slump changes. The study indicates that the proposed automated detection device can effectively evaluate the muck conditioning effect and reflect tunneling load variation, providing a reference for the dynamic optimization of shield construction parameters.

Key words: earth pressure balance shield, muck condition, automatic detection, slump