Background The jointed rock mass near the tunnel face is subjected to a biaxial stress state prior to blasting excavation, and its dynamic response is significantly influenced by the joint structure. However, existing research has been limited in its ability to reveal the fracture and ejection mechanisms of fully-penetrating cross-jointed rock under biaxial static-dynamic coupled loads, which consequently hampers the accurate prediction and effective prevention of related disasters. Objective This study aims to develop an integrated experimental mechanics approach to reveal the dynamic response characteristics and fracture-ejection evolution mechanism of fully-penetrating cross-jointed rocks under biaxial static-dynamic coupled loading. Methods A biaxial Hopkinson bar system was used to apply static-dynamic coupled loading to a fully penetrating cross-jointed rock specimen, and its dynamic mechanical response under different stress paths was systematically studied. The digital image correlation (DIC) technique was used to capture the crack evolution and rock block movement in real time, revealing the fracture-ejection behavior. Results The dynamic peak strength of jointed rock increases significantly with the increase of intermediate principal stress. For example, when the loading rate is 4300 GPa/s and the <InlineEquation ID="IEq1"> <EquationSource Format="TEX">${\sigma }_{2}^{0}$</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi>σ</mi> <mrow> <mn>2</mn> </mrow> <mn>0</mn> </msubsup> </math></EquationSource> </InlineEquation> increases from 6 to 12 MPa, the dynamic peak stress of the jointed rock sample increases from 41.6 MPa to 107.6 MPa, but decreases with the increase of maximum principal stress, revealing the high sensitivity of jointed rock mass to stress path. The rock shell exhibits compression-slip-rotation coordinated deformation, revealing the continuous evolution mechanism of rupture-slip-ejection under joint control. Conclusion The proposed BHPB-DIC experimental methodology successfully verifies the synergistic regulatory effect of joint structure and stress path on the dynamic response of rock mass. The proposed experimental method and mechanistic understanding can provide a theoretical basis and experimental support for the identification of dynamic hazards in jointed rock mass.

Experimental Study on Dynamic Mechanical Behavior of Fully-Penetrating Cross-Jointed Rocks Under Biaxial Static-Dynamic Loading

期刊论文
发表日期：

2026年3月13日

查看全文

X. Xiaokun,
X. Yifan,
S. Shaoshuai,
R. Xiaoli,
W. Weitao,
P. Jiangzhou,
H. Jie

摘要

Background

The jointed rock mass near the tunnel face is subjected to a biaxial stress state prior to blasting excavation, and its dynamic response is significantly influenced by the joint structure. However, existing research has been limited in its ability to reveal the fracture and ejection mechanisms of fully-penetrating cross-jointed rock under biaxial static-dynamic coupled loads, which consequently hampers the accurate prediction and effective prevention of related disasters.

Objective

This study aims to develop an integrated experimental mechanics approach to reveal the dynamic response characteristics and fracture-ejection evolution mechanism of fully-penetrating cross-jointed rocks under biaxial static-dynamic coupled loading.

Methods

A biaxial Hopkinson bar system was used to apply static-dynamic coupled loading to a fully penetrating cross-jointed rock specimen, and its dynamic mechanical response under different stress paths was systematically studied. The digital image correlation (DIC) technique was used to capture the crack evolution and rock block movement in real time, revealing the fracture-ejection behavior.

Results

The dynamic peak strength of jointed rock increases significantly with the increase of intermediate principal stress. For example, when the loading rate is 4300 GPa/s and the ${\sigma }_{2}^{0}$ $σ_{2}^{0}$ increases from 6 to 12 MPa, the dynamic peak stress of the jointed rock sample increases from 41.6 MPa to 107.6 MPa, but decreases with the increase of maximum principal stress, revealing the high sensitivity of jointed rock mass to stress path. The rock shell exhibits compression-slip-rotation coordinated deformation, revealing the continuous evolution mechanism of rupture-slip-ejection under joint control.

Conclusion

The proposed BHPB-DIC experimental methodology successfully verifies the synergistic regulatory effect of joint structure and stress path on the dynamic response of rock mass. The proposed experimental method and mechanistic understanding can provide a theoretical basis and experimental support for the identification of dynamic hazards in jointed rock mass.