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<p>Multi-stage cyclic loading tests with variable upper limits, conducted under various confining pressures, systematically probe the cyclic mechanical properties and accompanying acoustic emission (AE) characteristics of sandstone. Experimental results demonstrate a profound influence of confining pressure on the rock’s fatigue deformation patterns, strength degradation, and ultimate fatigue life. Analysis indicates that both the elastic modulus and irreversible strain accumulate progressively with cycle numbers at each stress level. Energy evolution is dominated by elastic strain energy, constituting approximately 95% of the total input. AE parameters, including peak frequency and b-value, reveal that higher confining pressures effectively restrict micro-crack propagation. Furthermore, the RA-AF analysis identifies a tensile-dominated mixed cracking mode. The damage evolution process is governed by a competition between hardening and damage mechanisms, where hardening prevails at low-stress stages and damage dominates subsequently. Elevated confining pressure enhances internal energy accumulation while constraining its release upon failure. These mechanistic insights informed the development of an optimized construction strategy for the Leye Tunnel. Its field application resulted in significantly improved deformation control and enhanced construction safety, offering valuable practical guidance for similar underground engineering projects in sandstone formations.</p>

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Mechanical properties and disaster-causing mechanism of sandstones under multistage low-cycle loading considering stress conditions

  • 期刊论文

  • 发表日期：

    2026年2月11日

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  • Liang Qian,
  • Xu Chen,
  • Chuan He,
  • Guowen Xu,
  • Bo Wang,
  • Mengchen Yun

摘要

Multi-stage cyclic loading tests with variable upper limits, conducted under various confining pressures, systematically probe the cyclic mechanical properties and accompanying acoustic emission (AE) characteristics of sandstone. Experimental results demonstrate a profound influence of confining pressure on the rock’s fatigue deformation patterns, strength degradation, and ultimate fatigue life. Analysis indicates that both the elastic modulus and irreversible strain accumulate progressively with cycle numbers at each stress level. Energy evolution is dominated by elastic strain energy, constituting approximately 95% of the total input. AE parameters, including peak frequency and b-value, reveal that higher confining pressures effectively restrict micro-crack propagation. Furthermore, the RA-AF analysis identifies a tensile-dominated mixed cracking mode. The damage evolution process is governed by a competition between hardening and damage mechanisms, where hardening prevails at low-stress stages and damage dominates subsequently. Elevated confining pressure enhances internal energy accumulation while constraining its release upon failure. These mechanistic insights informed the development of an optimized construction strategy for the Leye Tunnel. Its field application resulted in significantly improved deformation control and enhanced construction safety, offering valuable practical guidance for similar underground engineering projects in sandstone formations.