# Study on Dynamic Mechanical Properties and Failure Pattern of Thin-Layered Schist
## 6 Conclusions  
A dynamic impact test (SHPB) is carried out on thin-layered schist with different schistosity angles, the constitutive parameters of rock mass are calibrated by the test results, and the SHPB simulation model is established. The effects of the dynamic mechanical properties and failure pattern of thin-layered schist are studied and the main conclusions of this study are as follows:  
1. The stress-strain curves of thin-layered schist with different schistity angles are similar, and there are several significant stages in the curve under transient loading, including the elastic compression stage, plastic deformation stage and strain softening stage. The dynamic critical failure strength of each thin-layered schist conforms to the typical anisotropy characteristics of \"U\"-type strength. 2. For specimens with schistosity angles of 0\({}^{\circ}\)and 90\({}^{\circ}\), the main failure patterns are, respectively, axial splitting failure and splitting failure along the schistity plane. In the case of thin-layered schists with other schistosity angles, it is observed that the main failure pattern is significant shear failure, accompanied by local compression/shear composite failure characteristics. Figure 12: Comparison of failure patterns at different schistity spacing. Figure 13: Relationship between the dynamic compressive strength and schistity spacing. 3. With the decrease in schistosity spacing, the main failure pattern of thin-layered schist is significant shear failure; the damage degree of rock specimens is higher and more radial cracks are generated. In addition, the dynamic compressive strength decreases gradually and its value drops by up to 20.3% from the schistosity spacing of 22 mm to 7 mm. The dynamic mechanical properties and failure pattern of thin-layered schist with different schistosity angles and schistosity spacing are studied. The research results can provide theoretical guidance for schist tunnel blasting excavation and surrounding rock damage prevention and control. Methodology, Y.P. ; Software, P.C. and Y.Y. ; Validation, L.W. ; Investigation, Z.D. ; Writing--review & editing, G.L. All authors have read and agreed to the published version of the manuscript. This research was funded by the State Key Laboratory of Precision Blasting and the Hubei Key Laboratory of Blasting Engineering, Jianghan University (No. PBSKL2022D08); the Scientific Research Project of the Hunan Education Department (Grant no. 22B0486); and the Open Research Foundation of the Engineering Research Center of Rock-Soil Drilling & Excavation and Protection, Ministry of Education (202410). The APC was funded by the State Key Laboratory of Precision Blasting and the Hubei Key Laboratory of Blasting Engineering, Jianghan University, grant number No. PBSKL2022D08. Not applicable. **Data Availability Statement:** All data in this article were obtained from the authors' independent experiments and data processing using Origin 2024 software. Author [PERSON] was employed by the company CCCC Wuhan Harbour Engineering Design and Research Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. List of Symbols