Abstract: In tunnel engineering within layered rock masses,excavation induces stress redistribution in the surrounding rock,leading to increased horizontal stress in the tunnel floor and subsequent floor heave disasters under horizontal squeezing. Based on energy equilibrium,a formula for calculating the buckling deformation of horizontally layered tunnel floors was derived,and the failure behavior of such floors was analyzed by preparing horizontally layered rock beam specimens with varying layer thicknesses. The results indicate that due to the weak bonding strength of interlayer structural planes,the samples first undergo progressive separation from top to bottom along the bedding planes under horizontal compression. As horizontal squeezing stress increases,the flexural deformation of the floor gradually intensifies and propagates downward into lower layers. With increasing rock layer thickness,the horizontal bearing capacity of the rock beam increases,residual stress persists after the peak load,and vertical deformation progressively decreases. Thin-layered rock beams are primarily governed by maximum bending stress. As layer thickness increases,failure of the floor layers becomes predominantly controlled by the coupled action of bending and shear due to enhanced lateral shear forces. The failure mode of the floor layers gradually transitions from upward buckling failure to shear failure or splitting along bedding planes,accompanied by cone-shaped fractures at the ends.