Abstract: To address the challenge of cutterhead jamming of tunnel boring machine (TBM) when crossing complex geological conditions such as collapse columns, field measurements, theoretical analysis, and FLAC3D-PFC coupled numerical simulation methods are utilized to analyze the mechanism of TBM cutterhead jamming, and corresponding control strategies are proposed. The study reveals the heterogeneity and instability of the surrounding rock in the collapse column area, clarifying the progressive evolution process of cutterhead jamming. A control strategy centered on “advance detection, risk warning, support optimization, and dynamic regulation” is proposed. The main research conclusions are as follows: (1) Under the unfavorable geological conditions of collapse columns, the essence of cutterhead jamming is a multi-stage dynamic instability process caused by the coupling of “geological defects and construction disturbances”, which is manifested as the progressive failure of surrounding rock, accumulation of rock debris, and redistribution of surrounding rock pressure, ultimately leading to excessive cutterhead torque and jamming. (2) The surrounding rock in the collapse column area exhibits asymmetric mechanical responses characterized by significant roof settlement and concentrated stress on the sidewall. The roof mainly exhibits vertical unloading and continuous subsidence, while the sidewall becomes a key area for stress transfer and support, easily leading to spalling and uneven deformation. (3) Based on the mechanism of cutterhead jamming and simulation results, targeted control strategies are proposed, including advance detection and pre-treatment, differentiated support design, optimized construction methods, and dynamic adjustment of construction parameters, aiming to transition from “passive response” to “active control”, improving TBM safety and adaptability under complex geological conditions.

Key words: open-type tunnel boring machine, collapse column, cutterhead jamming mechanism, numerical simulation, prevention strategy