Failure analysis of progressive instability and deformation law of excavation face in sand cobble stratum under cutting disturbance by shield cutter

Shield construction plays a crucial role in the development of underground infrastructure. However, as a complex engineering process, it can lead to excavation face instability and surface subsidence. This paper presents a detailed investigation into the mechanisms influencing excavation face instability and surface subsidence of sand cobble stratum during shield construction using the discrete element method (DEM). Through a combination of numerical simulations and experimental analyses, the impact of various parameters, including support pressure, and cutters on the stability of the excavation face were explored. The results reveal that the presence of cutters significantly enhances particle fluidity but weakens the stability of the excavation face, necessitating a higher ultimate support pressure. Furthermore, the study highlights the distinct behavior of surface subsidence compared to excavation face instability. Surface subsidence exhibits a delayed manifestation, even when soil overflows into the shield machine. This finding underscores the importance of diligent monitoring and control of cabin pressure during shield construction. The findings provide valuable insights into the intricate dynamics of shield construction and offer practical recommendations for minimizing excavation face instability and surface subsidence.