During tunnel construction in weak strata, the coupled effects of ground rheological behavior and stress release significantly influence both construction progress and safety. As a critical support measure in tunneling engineering, the time-dependent mechanical interaction between rock bolts and the surrounding rock under such complex conditions remains insufficiently understood. To elucidate the time-dependent interaction mechanism between rock bolts and surrounding rock under these challenging engineering conditions, this study develops an analytical solution for bolted tunnels that explicitly couples tunnel excavation-induced stress release and ground rheology. The rheological behavior of the ground is characterized using classical Maxwell and Kelvin-Voigt creep models, while the stress release effect is represented through the virtual support pressure method. A closed-form analytical solution is ultimately derived via integral transforms. The solution accounts for two types of rock bolts: end-anchored rock bolts and fully grouted rock bolts, which are distinguished by modifying the contact conditions at the boltrock interface. Numerical simulations verify the validity and engineering applicability of the proposed analytical method. Furthermore, parametric studies are conducted to examine the influence of bolt parameters and stress release parameters on surrounding rock deformation. The proposed analytical approach provides researchers and engineers with an improved theoretical understanding of the interaction between rock bolts and tunnel surrounding rock in weak strata.
Haixiang Lai, Baoguo Liu, Xiaomeng Shi et al.· International Journal of App...· 0 citations
The dynamic compression fracture of brittle rock under seepage pressure is a critical issue for deep underground engineering. It directly influences the stability and safety of the surrounding rock during blasting or seismic loading. However, research on the mechanisms of microcrack evolution under these coupled conditions is still lacking. The relationship between microcrack evolution and macroscopic mechanical properties also remains poorly understood. This study develops a micro–macrofracture model grounded in the wing microcrack propagation framework, integrating both mechanical and chemical interactions between free water and rock. Mechanically, it incorporates seepage pressure, dynamic Stefan force, and dynamic fracture toughness. Chemically, it accounts for the effects of saturated water on rock mechanical parameters. This model characterizes the total stress–strain constitutive behavior of brittle rock under varying seepage pressures during dynamic compression failure, encompassing both strain-hardening and strain-softening phases. This result is validated against experimental data. It accounts for the influence of seepage pressure on both the initial crack and the newly formed wing crack. The seepage pressure weakens the wedging force
F
W
on the initial crack while enhancing the seepage tensile force
F
P
on the wing crack, which constitutes the seepage pressure-driven crack growth mechanism. Furthermore, under the combined effects of dynamic loading and free water, the dynamic Stefan force
F
S
and the dynamic fracture toughness
K
ICD
serve as the mechanism for inhibiting crack growth. The combined influences of seepage pressure, confining pressure and initial crack characteristics on the dynamic mechanical behavior of brittle rock under seepage pressure are discussed.
Xiaozhao Li, Qiulin Luo, Zhuoxian Zhang et al.· International Journal of Geo...· 0 citations