## 1 Introduction  
Since the beginning of the 21 st century, under the backdrop of long-term, rapid, and high-quality economic development in China, the demand for high-speed cross-regional resource flows has significantly increased, leading to a rapid development trend in the construction of the national transportation network [1; 2]. In the central and western regions of China, tunnels are often built through weak surrounding rock formations. These formations typically include sandstone, sandy mudstone, muddy sandstone, slate, genesis, carbonaceous slate, shale, and other layered weak rocks with distinct anisotropic mechanical properties and failure modes [3; 4]. Among these, soft-hard interbedded rock is a typical example, and its complex rock structure poses significant challenges to the design and construction of deep-buried layered weak rock tunnels in the western regions of China. Therefore, it is of great significance to carry out the research and prediction of the failure mechanism of soft-hard interbedded rock for the safety of ongoing construction projects. At present, a large number of effective experimental studies on layered rock masses have been carried out by scholars both domestically and internationally. For instance, [PERSON] et al. [5; 6] conducted uniaxial and triaxial compression experiments in the laboratory, studied the influence of varying \(\alpha\) on the mechanical properties and elastic modulus of rock, and gave its failure criterion. [PERSON] et al. [7] performed uniaxial and triaxial compression tests on schist to examine the applicability of nonlinear strength criteria in predicting compressive strength and elastic modulus. [PERSON] et al. [8] conducteduniaxial compression tests and Brazilian splitting tests on gneiss, investigating five elastic parameters of transversely isotropic rocks. [PERSON] et al. [9] carried out direct shear tests on shale specimens, analyzing the variation of shear parameters with bedding angles and studying the impact of bedding plane orientation on the shear strength and failure mechanism of shale. Based on laboratory experiments, [PERSON] et al. [10] developed a failure model for analyzing the failure probability of anti-dip interlayer rock slopes. The study indicates that the shoulder, toe, and weak layers of the slope are more prone to failure, while the slope posterior remains relatively stable. [PERSON] et al. [11] studied the impact of mechanical properties and thickness of rock layers on the bending fracture behavior of underground rock caverns through three-point bending tests. They found that as the tensile strength of hard rock, cohesion of soft rock, and the layer thickness ratio increase, the peak load of the bending fracture of the samples also increases. [PERSON] et al. [12] used the No. 3 inclined shaft of the Muzhaling Tunnel as an engineering example to conduct large-scale geomechanical model tests of tunnel excavation and loading, revealing that an increase in the lateral pressure coefficient leads to bedding plane sliding and surrounding rock deformation. Additionally, based on numerical simulations, they discovered that as the bedding plane spacing increases, the maximum displacement decreases and progressively increases from the floor to the roof. These studies have provided a clear understanding of the deformation and failure of layered rock masses under different conditions. The essence of rock failure is a state of instability driven by energy. Therefore, researching the energy evolution mechanism of rocks helps to reveal the damage evolution process and deformation mechanisms of rocks. For instance, [PERSON] et al. [13] studied the variation pattern of critical strain energy density and discovered that the critical strain energy density factor of rock exhibits an exponential relationship with the loading rate. [PERSON] et al. [14] determined the stability of crack initiation and propagation in cross-connected specimens with openings by examining different stages of energy dissipation ratios. [PERSON] et al.