Understanding the failure mechanism of soft rock roadways in high-humidity environments, as well as designing appropriate control measures, are critical for ensuring their stability. In this study, swelling and triaxial compression tests on argillaceous sandstone were first performed. Results show that the triaxial compressive strength (TCS), elastic modulus, cohesion, and internal friction angle of argillaceous sandstone are all decreased due to the water weakening effect. Then, a self-developed finite-element-based numerical code was employed to elucidate the role of humidity diffusion in the deformation and failure of soft rock roadways. Simulation results indicate that under the influence of humidity, high stress concentration zones develop, initiating microcracks within these regions. As humidity continues to diffuse, the high stress concentration zones expand and migrate deeper into the surrounding rock, causing microcracks to propagate and accelerating humidity diffusion. This cyclical process repeats, ultimately resulting in macroscopic fracturing. The failure of roadway exhibits a tensile–shear mixed mode during humidity diffusion. A comparative analysis of four control measures reveals that conventional non-waterproof shotcrete primary support is of limited effectiveness in ensuring the stability of high-humidity soft rock roadways. It is essential to promptly establish a closed waterproof support structure. Furthermore, localized support defects significantly impact control effectiveness.
Xin Liang, Chun’an Tang, Lihua Hu et al.· Applied Sciences· 0 citations
Water significantly modifies rock mechanical performance and fracture characteristics through water content and water distribution. Nevertheless, the evolution laws of rock mechanical properties and underlying fracture mechanisms under variable water conditions remain incompletely clarified. In this study, uniaxial compression tests were carried out on sandstone samples with diverse water immersion durations. Experimental observations reveal that the uniaxial compressive strength (UCS) and elastic modulus of sandstone follow negative exponential attenuation with prolonged immersion time, with maximum reductions of 50.1% and 25.6%, respectively. Under equivalent water contents, samples featuring dry exteriors and wet interiors possess lower strength than those with wet exteriors and dry interiors. A self-developed numerical code incorporating humidity diffusion effects was subsequently adopted to interpret water-controlled sandstone fracture behaviors. Numerical outputs verify that water-induced softening and heterogeneous water distribution exacerbate rock material heterogeneity and internal stress non-uniformity, triggering tensile microcracks along dry–wet interfaces. As the immersion duration rises, the rock failure mode transitions from shear-dominated mixed failure to tension-dominated failure, and finally reverts to shear-dominated mixed failure. Macroscopic rupture is predominantly governed by the gradual coalescence of tension-generated microcracks. This study offers a theoretical foundation to advance the understanding of water-triggered mechanical degradation and fracture mechanisms in sandstone.