Characteristics of Deformation and Damage of Multi‐Thin Composite Oil Shale Top Plate Under the Influence of Different Factors

ABSTRACT Subjected to the combined action of the gravity‐induced load from the upper surrounding rock and the in‐situ horizontal tectonic stress, the oil shale roof is highly susceptible to interlayer separation, slip displacement, and bending deformation. Consequently, the stability and support challenge associated with this type of roadway roof structure is becoming increasingly prominent, necessitating an urgent determination of the oil shale roof's deformation and failure characteristics. In this study, a mechani al and numerical modeling framework was developed using engineering geological tests, theoretical analyses, and UDEC‐Trigon simulations to assess the sensitivity of key factors affecting the stability of the roadway and to analyze the evolution of cracks, displacements, and stresses. The results show that (1) rock beam thickness is inversely related to internal force with high sensitivity, while lateral pressure coefficients are positively correlated with the roadway span, but with lower sensitivity; (2) greater overburden loads, lateral pressure deviations, and spans increase the height of the tension zone and decrease the beam stiffness, while the modulus of elasticity has a stabilizing effect; and (3) an increase in the overburden load, lateral pressure deviations, and number of delaminations significantly contributes to the development of fractures and the displacements of delaminations, the reshape the stress distribution of the surrounding rock. The results provide theoretical guidance for the design and control of tunnel stability in similar engineering environments.