## 1 Introduction
[20] proposed a mechanical model of asymmetric floor heave and demonstrated that the stability of the roadway floor is influenced by the stress concentration coefficient of the roadway sidewalls and the burial depth of the roadway. As the burial depth increases, the displacement of the surrounding rock in the tunnel also increases to varying degrees. Horizontal stress plays an important role in the stress conditions of the surrounding rock. Under high horizontal stress conditions, the laminated rock at the bottom of a tunnel is prone to interlayer delamination, deflection, and deformation damage [21]. [PERSON] et al. investigated the floor heave at the bottom of the tunnel under biaxial loading by pouring soft and hard interlayer cement. The analysis of the stress distribution within the tunnel structure indicated that the predominant factor contributing to floor heave was the presence of significant horizontal stress [18]. The rise in horizontal ground stress led to notable extensions of the feeble stratum and the transfer of the primary bearing strata [5]. [PERSON] et al. [16] concluded that mainly high horizontal stresses with greater depths of cover and certain types of floor lithology configuration are likely to contribute to the failures of floor strata. They investigated the relatively hard tuff layers with higher strength and ruled out the possibility of bearing capacity failure. The primary internal factors leading to roadway floor heave in weakly cemented soft rock are high stress and strong disturbances [22]. Currently, research on floor heave mainly focuses on indoor model experiments or numerical simulations of soft rock or soft interbedded pouring samples. However, there are limited indoor experimental studies on the mechanism of floor heave in natural layered hard rocks. The extensive engineering practices have demonstrated that the layered structure of rocks is one of the significant factors contributing to floor heave [23; 24; 25; 26]. Common layered rocks include schist, gneiss, slate, and shale. Many studies have been performed on the physical and mechanical characteristics of layered rocks. To investigate the transverse anisotropy on strength and deformational responses of schist, [PERSON] et al. [27] conducted uniaxial compressive strength tests on rock specimens with schist using from 0\({}^{\circ}\) to 90\({}^{\circ}\) with respect to the axial stress and performed triaxial tests under five different confining stresses. The predicted values of strength and modulus were found to closely match the experimental stress-strain curves using a nonlinear strength criterion. The rock sample mainly exhibited tensile splitting and buckling of compression when the load was applied parallel to the schisty plane. In addition, the surrounding rock of tunnels was susceptible to shear sliding along the schisty plane when passing through horizontal schisty planes [28]. [PERSON] et al. [29] illustrated that the interlayer strength of the structural plane of the rock affects the rupture process, and the tensile cracks at the interlayer level were characterized in their study by the digital image correlation (DIC) technique. The tensile cracks propagated mainly along the loading direction, and the weak face played a buffering role against deformation. The thinly bedded configuration may be the cause of the buckling, as it continued even after the immediate floor was fractured [16]. To demonstrate the impact of microcracks or fabric anisotropy on the mechanical and physical properties of rocks, [PERSON] et al. [30] investigated the effect of fracture orientations on the longitudinal wave velocity in dry and saturated rocks. Velocity anisotropy arises mainly from the preferred orientation of microcracks and is used to predict the anisotropic behavior in other mechanical or physical properties.