## 5 Conclusions  
This study implemented three anisotropic strength criteria (SPW, PPW, and Pariseau) through least-squares optimization to simulate the strength characteristics of 12 stratified rock types. Predictive performance was quantitatively assessed across varying confining pressures and bedding orientations through RMSE, R\({}^{2}\), and MAE analyses, establishingrigorous benchmarks for each criterion's ability to replicate experimental strength profiles in anisotropic geological media. The research findings indicate that the anisotropy of layered rock strength decreases with decreasing confining pressures. Under low confining pressures, the anisotropy value decreases rapidly with increasing confining pressure. Conversely, at high confining pressures, the anisotropy variation diminishes. Analyzing the strength of layered rocks at different bedding angles reveals that perpendicular bedding rock strength surpasses parallel bedding rock strength. Additionally, within the range of bedding angles 0\({}^{\circ}\) to \(\beta_{1}\) and \(\beta_{2}\) to 90\({}^{\circ}\), the strength of layered rocks is lower than the intact rock strength. The observed strength variations stem from fundamental differences in failure mechanisms relative to bedding plane orientation. When loading aligns with bedding planes (0\({}^{\circ}\)), the rock exhibits diminished capacity due to preferential fracturing along these planes of weakness. Conversely, perpendicular loading (90\({}^{\circ}\)) induces matrix-dominated failure through intact rock material, achieving maximum strength comparable to non-stratified specimens. Notably, intermediate orientations (\(\beta_{1}\)-\(\beta_{2}\) range) reveal hybrid failure modes, combining cross-bedding shear fracturing and bedding-parallel sliding. This composite mechanism produces transitional strength values exceeding pure bedding plane failure but remaining inferior to intact rock performance. The resultant strength profile therefore demonstrates an angular dependence governed by competing failure pathways--bedding plane activation versus matrix shearing--with the critical transition angles \(\beta_{1}\) and \(\beta_{2}\) demarcating the boundaries between dominant failure modes. Regarding the anisotropic strength criteria, the SPW criterion predicts a \"shoulder-shaped\" strength curve for rocks at different bedding angles, overestimating the strength of rocks within the ranges of 0\({}^{\circ}\) to \(\beta_{1}\) and \(\beta_{2}\) to 90\({}^{\circ}\), leading to significant predictive errors in layered rock strength. In contrast to other approaches, the PPW criterion characterizes rock strength variation across bedding orientations through a distinctive undulating curve governed by parameter \(\eta\), demonstrating its versatility in modeling rocks with diverse anisotropic characteristics. This formulation effectively captures the complex interplay between intact shear failure and bedding plane sliding mechanisms while maintaining adaptability to varying lithological compositions and confining pressure conditions. A notable limitation, however, lies in its inability to differentiate strength properties between orthogonal and parallel bedding orientations. [PERSON]'s model presents an alternative framework through a unified mathematical expression that seamlessly bridges distinct failure regimes--from shear fracturing through transitional mixed modes to planar sliding--achieving continuous strength prediction across the full stress spectrum. While this integrated formulation successfully discriminates strength differences between perpendicular and parallel bedding configurations, its capacity to accurately predict strength parameters across heterogeneous layered rock formations proves marginally inferior to the PPW criterion's performance. The comparative analysis reveals a fundamental trade-off between model universality and lithology-specific predictive precision in anisotropic rock mechanics.