天然岩体因其复杂的成岩过程而赋存大量裂隙和孔隙，岩体工程的失稳破坏通常是由其内部裂隙的扩展和贯通所引起。随着寒区岩体工程的增多，研究冻融环境下裂隙因素对岩体长期稳定性的影响变得尤为重要。鉴于此本文以不同倾角预制双裂隙岩石为主要研究对象，开展冻融循环后单轴压缩声发射试验和蠕变声发射试验，分析冻融次数和裂隙倾角对岩石的损伤特性、力学特性、蠕变特性及声发射特征的影响，研究损伤过程中b值和损伤变量演化规律，并对岩石蠕变破坏前兆差异进行了分析。主要研究内容和结论如下：

（1）为探究冻融循环和裂隙倾角对岩石的损伤特性、力学特性和声发射特性的影响，开展冻融循环试验和单轴压缩声发射试验，揭示宏观力学特性与声发射特性之间的联系，并建立基于声发射参数的损伤模型。研究结果表明：随着冻融循环次数的增加，岩石冻融损伤变量呈指数型增加；冻融循环和裂隙倾角的变化对岩石物理力学性能产生较大影响；声发射振铃计数和三维事件分布特征反映出岩石破裂过程；声发射b值整体保持上下波动状态，裂隙倾角的增大，引起b值在应力最高处更加密集；裂隙岩石的损伤过程分为3个阶段，冻融循环加速了岩石的初始损伤累积，裂隙倾角越大，损伤加速阶段的斜率越大。

（2）为探究冻融循环和裂隙倾角对岩石蠕变特性和破坏模式的影响，进行蠕变声发射试验。试验结果表明：裂隙倾角的变化影响岩石的破坏模式；冻融循环作用加剧岩石表面的破裂，导致破坏裂纹增多；冻融循环和裂隙倾角的增大使岩石的蠕应变增加。稳态蠕变速率随着冻融循环次数的增加呈指数型增长，并且随着裂隙倾角的增大而变大。此外，岩石的长期强度会随着冻融循环次数的增加而快速降低，但裂隙倾角的增大则会提高岩石的长期强度。

（3）基于声发射技术，分析冻融作用下裂隙岩石蠕变过程中声发射参数及b值变化特征，研究岩石破坏声发射前兆特征。研究结果表明：振幅和AE能率的变化趋势反映了岩石破坏过程，能够体现出不同冻融次数和裂隙倾角之间的破坏差异。裂隙倾角的增大会使岩石蠕变过程中的裂纹扩展和贯通趋于稳定和连续，岩石稳定性增强。冻融循环的增加引起振幅和AE能率的提高，但随着应力加载等级的提升，这种影响逐渐趋于消散。声发射b值在减速和等速蠕变阶段呈上升趋势，进入加速蠕变阶段后则出现快速下降现象；冻融作用使岩石在减速蠕变阶段由小尺度破坏转变为大尺度破坏；双裂隙倾角的减小会降低岩石的稳定性，加快减速蠕变阶段的b值波动；预制裂隙的存在会使b值预测破坏时间点提前，而冻融循环作用则会使b值预测破坏时间点延后；声发射b值能够有效地预示岩石的失稳破坏，可作为一种有效的岩石蠕变破坏的前兆信息。

综上所述，本文结合声发射技术对冻融作用下裂隙岩石力学及蠕变特性进行了全面分析，研究结论可以为寒区裂隙岩体的破坏规律和预测破坏提供参考。

Natural rock mass has a large number of cracks and pores due to its complex diagenesis process. The instability and failure of rock mass engineering is usually caused by the expansion and penetration of its internal cracks. With the increase of rock mass engineering in cold regions, it is particularly important to study the influence of fracture factors on the long-term stability of rock mass under freeze-thaw environment. In view of this, this paper takes the prefabricated double-fractured rock with different dip angles as the main research object, carries out uniaxial compression acoustic emission test and creep acoustic emission test after freeze-thaw cycle, analyzes the influence of freeze-thaw times and crack dip angle on the damage characteristics, mechanical properties, creep characteristics and acoustic emission characteristics of rock, studies the evolution law of b value and damage variable in the damage process, and analyzes the difference of rock creep failure precursor. The main research contents and conclusions are as follows :(1) In order to explore the effects of freeze-thaw cycles and fissure inclination on the damage characteristics, mechanical properties and acoustic emission characteristics of rock, freeze-thaw cycle tests and uniaxial compression acoustic emission tests were carried out to reveal the relationship between macroscopic mechanical properties and acoustic emission characteristics, and a damage model based on acoustic emission parameters was established. The results show that with the increase of freeze-thaw cycles, the freeze-thaw damage variable of rock increases exponentially. The change of freeze-thaw cycle and crack dip angle has a great influence on the physical and mechanical properties of rock. Acoustic emission ringing count and three-dimensional event distribution characteristics reflect the rock failure process. The b value of acoustic emission keeps fluctuating up and down as a whole, and the increase of fracture dip angle causes the b value to be more dense at the highest stress. The damage process of fractured rock is divided into three stages. The freeze-thaw cycle accelerates the initial damage accumulation of rock. The larger the fracture dip angle, the greater the slope of the damage acceleration stage.

(2) In order to explore the effects of freeze-thaw cycles and fracture inclination on the creep characteristics and failure modes of rock, creep acoustic emission tests were carried out. The test results show that the change of fracture dip angle affects the failure mode of rock. The freeze-thaw cycle intensifies the fracture of the rock surface, resulting in an increase in damage cracks. The increase of freeze-thaw cycles and fracture dip angle increases the creep strain of rock. The steady-state creep rate increases exponentially with the increase of freeze-thaw cycles, and increases with the increase of crack dip angle. In addition, the long-term strength of rock will decrease rapidly with the increase of freeze-thaw cycles, but the increase of fracture dip angle will improve the long-term strength of rock.

(3) Based on acoustic emission technology, the variation characteristics of acoustic emission parameters and b values in the creep process of fractured rock under freeze-thaw action are analyzed, and the precursor characteristics of acoustic emission in rock failure are studied. The results show that the variation trend of amplitude and AE energy rate reflects the rock failure process, which can reflect the failure difference between different freeze-thaw times and fracture dip angles. The increase of fracture dip angle will make the crack propagation and penetration in the process of rock creep tend to be stable and continuous, and the stability of rock is enhanced. The increase of freeze-thaw cycles leads to the increase of amplitude and AE energy rate, but with the increase of stress loading level, this effect tends to dissipate. The acoustic emission b value shows an upward trend in the deceleration and constant creep stages, and a rapid decline occurs after entering the accelerated creep stage. The freeze-thaw action makes the rock change from small-scale failure to large-scale failure in the deceleration creep stage. The decrease of the dip angle of the double fissures will reduce the stability of the rock and accelerate the fluctuation of the b value in the deceleration creep stage. The existence of prefabricated cracks will advance the predicted failure time point of b value, while the freeze-thaw cycle will delay the predicted failure time point of b value. Acoustic emission b value can effectively predict the instability and failure of rock, which can be used as an effective precursor information of rock creep failure.

In summary, this paper combines acoustic emission technology to comprehensively analyze the mechanics and creep characteristics of fractured rock under freeze-thaw action. The research conclusions can provide reference for the failure law and prediction of fractured rock mass in cold regions.

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