【摘要】 【目标】以西藏玉龙铜矿公路边坡的砂岩为研究对象，探究冻融循环作用对饱水砂岩能量演化与破坏前兆特征的影响。【方法】采用冻融循环试验箱对岩样进行预处理，开展不同冻融循环次数下的静态压缩试验和实时声发射监测试验，分析冻融饱水砂岩的力学特性及破坏过程中的声发射特征。结合临界慢化理论，阐述冻融作用下饱水砂岩的破坏前兆特征。【结果】饱水砂岩的抗压强度、弹性模量和总应变能均随冻融次数的增大而减小，120次冻融后，与未冻融时相比，抗压强度降低34.38%,弹性模量降低22.66%,总应变能降低29.77%;随着冻融次数的增加，试样由张拉破坏为主的张剪破坏，逐渐转化为以剪切破坏为主的“X”型剪切破坏；声发射b值、振铃计数方差和自相关系数的前兆点均可作为试样破坏前兆的判据，预测破坏时间随着冻融次数的增加而增加，120次冻融后，三者的预测破坏时间依次比试样破坏时刻提前45.9,68.4,73.2 s。【结论】与声发射b值的预测破坏时间相比，振铃计数方差和自相关系数的预测破坏时间更早。更多还原

【Abstract】 [Objective]Taking the sandstone collected from highway slope at Yulong copper mine in Tibet, this study investigated how freeze-thaw cycles affect the energy evolution and failure precursors of water-saturated sandstone. [Method] The sandstone samples were pretreated by using a freeze-thaw cycling test chamber. Static compression tests and real-time acoustic emission monitoring tests were conducted under different freeze-thaw cycles. The mechanical properties of freeze-thaw water-saturated sandstone and the acoustic emission characteristics during failure process were analyzed. The failure precursors of water-saturated sandstone in freeze-thaw conditions were illustrated based on the critical slowing down theory. [Result] The compressive strength, elastic modulus, and total strain energy of water-saturated sandstone decreased with freeze-thaw cycles increasing. Compared with those at unfrozen state, the compressive strength decreased by 34.38%, the elastic modulus decreased by 22.66%, and the total strain energy decreased by 29.77% after 120 cycles. With more freeze-thaw cycles, the failure mode of samples gradually changed from tensile-dominated tensile-shear failure to shear-dominated X-type shear failure. The b-value of acoustic emission, ring-down count variance and autocorrelation coefficient all served as failure precursory criteria. The predicted failure moment increased with freeze-thaw cycles. After 120 cycles, the failure moments predicted with b-value of acoustic emission, ring-down count variance and autocorrelation coefficient preceded the actual failure moment by 45.9 s, 68.4 s, and 73.2 s respectively. [Conclusion] The failure moments predicted with ring-down count variance and autocorrelation coefficient are both earlier than that predicted with b-value of acoustic emission.更多还原