随着季冻区交通基础设施和能源开发需求不断增加，已建成的青藏铁路、新疆天山公路和在建的川藏铁路等重大交通基础工程沿线的高陡边坡及大型露天矿山开采边坡的充填裂隙岩体在冻融与周期荷载作用下的多种灾害严重影响其长期稳定性。本文以充填裂隙红砂岩为研究对象，采用室内试验、数值模拟以及理论分析相结合的方法进行研究，主要结论如下：

（1）完成了冻融循环试验，并对不同冻融次数的岩样进行了波速与质量的测定，结果表明：冻融后充填裂隙红砂岩质量有不同程度的损失，损伤程度与冻融循环次数呈正相关，受蓄水能力与颗粒剥落两个因素控制；而岩样纵波波速与冻融循环次数近似呈线性反比关系，可通过波速量化与反映岩样冻融损伤情况。

（2）完成了不同冻融循环次数作用下不同强度裂隙充填物充填红砂岩的三轴压缩及声发射监测试验。试验结果表明：充填裂隙红砂岩峰值强度随充填物的强度增大而增长，充填裂隙红砂岩破坏时裂纹发展沿充填裂隙处扩展；随冻融循环次数的增多，充填裂隙红砂岩峰值强度衰减趋势越来越明显，破坏形态更加彻底，声发射试验在“沉寂期”内的计数增多；随着围压的增加，不同强度裂隙充填物充填红砂岩的峰值应力呈上升的趋势，岩样破裂面的贯通模式由张拉破坏转变为张拉剪切复合破坏最后过渡到整体剪切破坏。声发射累计振铃计数与应力-应变曲线变化趋势具有明显的规律性，能够表达出裂纹的开裂、扩展的变化过程。

（3）完成了冻融循环40次后充填裂隙红砂岩周期荷载试验及全过程声发射监测试验。试验结果表明：充填裂隙红砂岩周期荷载的应力-应变曲线呈现为“疏－密－疏”的变化规律，轴向变形曲线均符合初始阶段、等速阶段及加速阶段的三阶段变化趋势，充填M15强度水泥砂浆红砂岩疲劳特性强于充填M7.5强度的红砂岩；振幅对于充填裂隙红砂岩疲劳特性影响较显著，随着应力振幅的增加，充填裂隙红砂岩的疲劳寿命逐渐减小，岩样破坏模式从拉伸破坏转变成拉剪混合破坏，破坏程度加剧；随着围压的增加，等速阶段持续的循环次数增加，岩样的疲劳极限提高；声发射信号集中于周期荷载加载初期及岩样破坏阶段，对应岩样受周期荷载时的三个变形阶段，故可通过其变化规律对岩样的损伤状态进行判断。

（4）完成了冻融作用、静态荷载作用以及周期荷载作用前后不同强度充填物充填红砂岩核磁共振试验。试验结果表明：充填裂隙红砂岩T₂谱均存在3个主峰，第1峰和第2峰核磁共振信号占比较大，第3峰占比较小，孔径分布主要在0.1~1000μm；随冻融循环次数增加，岩样T₂谱曲线覆盖区间变大，信号强度增加，微孔、小孔占比逐渐减少，大孔占比逐渐增多，峰总面积增加；静态荷载压缩破坏后T₂谱峰值信号明显增大，第2峰增幅显著，第3峰更加明显，冻融作用下压缩破坏后谱面积也越大，说明冻融损伤易提高岩样的破坏程度；在周期荷载作用破坏后T₂谱面积较压缩破坏增幅更大，峰总面积变化率更高，从细观特征变化验证了岩样受周期荷载作用裂纹扩展更加充分，岩样破坏更加彻底。

（5）依据断裂力学应变能理论推导出充填裂隙对红岩造成的损伤量，结合孔隙率表征的冻融损伤，基于经典Bingham模型，用循环次数与频率换算代替蠕变时间，将模型中弹性元件以及常值黏壶原件替换为与循环次数相关的元件，将周期荷载等效分解为静力荷载与交变荷载得到冻融循环后周期荷载作用下的充填裂隙红砂岩疲劳本构模型。结合室内试验数据进行数据拟合，模型能够较好的描述周期荷载试验的变形三阶段，验证了模型的适用性。

With the increasing demand for transportation infrastructure and energy development in the seasonally frozen area, the high and steep slopes along the major transportation infrastructure projects such as the Qinghai-Tibet Railway, the Tianshan Highway in Xinjiang, and the Sichuan-Tibet Railway under construction, and the fractured rock mass of large-scale open-pit mining slopes under freeze-thaw and periodic loads. A variety of disasters seriously affect its long-term stability. In this paper, the filling fracture red sandstone is taken as the research object, and the method of indoor test combined with numerical simulation and theoretical analysis is used to study. The main conclusions are as follows :

(1) The freeze-thaw cycle test was completed, and the wave velocity and quality of rock samples with different freeze-thaw times were measured. The results show that the quality of red sandstone filled with fissures after freeze-thaw has different degrees of loss. The degree of damage is positively correlated with the number of freeze-thaw cycles, and is controlled by two factors : water storage capacity and particle spalling. The longitudinal wave velocity of rock samples is approximately linearly inversely proportional to the number of freeze-thaw cycles, and the freeze-thaw damage of rock samples can be quantified and reflected by wave velocity.

(2) The triaxial compression and acoustic emission monitoring tests of red sandstone filled with different strength fracture fillings under different freeze-thaw cycles were completed. The test results show that the peak strength of the filling fracture red sandstone increases with the increase of the strength of the filling material, and the crack develops along the filling fracture when the filling fracture red sandstone is destroyed. With the increase of freeze-thaw cycles, the attenuation trend of peak strength of red sandstone filled with fissures is more and more obvious, the failure mode is more thorough, and the count of acoustic emission test in the ' silent period ' is increased. With the increase of confining pressure, the peak stress of red sandstone filled with different strength fracture fillings shows an upward trend, and the transfixion mode of the fracture surface of the rock sample changes from tensile failure to tensile-shear composite failure and finally to overall shear failure. The cumulative ringing count of acoustic emission and the change trend of stress-strain curve have obvious regularity, which can express the change process of crack cracking and expansion.

(3) The periodic load test and the whole process acoustic emission monitoring test of red sandstone with filling cracks after 40 freeze-thaw cycles were completed. The test results show that the stress-strain curve of the periodic load of the filling fracture red sandstone presents the change rule of ' sparse-dense-thin ', and the axial deformation curve conforms to the three-stage change trend of the initial stage, the constant speed stage and the acceleration stage. The fatigue characteristics of the red sandstone filled with M15 strength cement mortar are stronger than those of the red sandstone filled with M7.5 strength ; the amplitude has a significant effect on the fatigue characteristics of red sandstone with filling cracks. With the increase of stress amplitude, the fatigue life of red sandstone with filling cracks decreases gradually, and the failure mode of rock samples changes from tensile failure to tensile-shear mixed failure, and the degree of damage increases. With the increase of confining pressure, the number of cycles in the constant velocity stage increases, and the fatigue limit of the rock sample increases. The acoustic emission signal is concentrated in the initial stage of cyclic loading and the failure stage of rock specimen, which corresponds to the three deformation stages of rock specimen under cyclic loading. Therefore, the damage state of rock specimen can be judged by its variation law.

(4) The nuclear magnetic resonance tests of red sandstone filled with different strength fillings before and after freeze-thaw action, static load action and periodic load action were completed. The results show that there are three main peaks in the T₂ spectrum of red sandstone filled with fissures. The first and second peaks of nuclear magnetic resonance signals account for a large proportion, and the third peak accounts for a small proportion. The pore size distribution is mainly in the range of 0.1 ~ 1000 μm. With the increase of the number of freeze-thaw cycles, the coverage range of the T₂ spectrum curve of the rock sample becomes larger, the signal intensity increases, the proportion of micropores and small pores gradually decreases, the proportion of large pores gradually increases, and the total peak area increases. After static load compression failure, the peak signal of T₂ spectrum increases obviously, the second peak increases significantly, the third peak is more obvious, and the spectral area after compression failure under freeze-thaw action is also larger, indicating that freeze-thaw damage can easily improve the damage degree of rock samples. After the failure of periodic load, the area of T₂ spectrum increases more than that of compression failure, and the change rate of total peak area is higher. From the change of mesoscopic characteristics, it is verified that the crack propagation of rock specimen under periodic load is more sufficient and the failure of rock specimen is more thorough.v

(5) Combined with the freeze-thaw damage characterized by porosity, based on the classical Bingham model, the number of cycles and frequency conversion are used to replace the creep time. The elastic element and the constant sticky pot element in the model are replaced by the elements related to the number of cycles. The periodic load is equivalently decomposed into static load and alternating load to obtain the fatigue constitutive model of red sandstone with filling cracks under periodic load after freeze-thaw cycles. Combined with the indoor test data for data fitting, the model can better describe the three stages of deformation of periodic load test, and verify the applicability of the model.