【摘要】 为研究冻融循环和疲劳荷载协同作用对水泥沥青砂浆(CA砂浆)性能劣化的影响，通过单一冻融循环、单一疲劳加载及先冻融后疲劳加载三种损伤试验，分析了不同致损因素下CA砂浆的表面形态与最终破坏模式变化，以及变形曲线、抗压强度、相对弹性模量等相关参数的劣化规律，并通过计算机断层扫描(CT)对试件内部损伤发展进行阶段性跟踪，配合扫描电镜试验，从微观层面探寻其损伤机理。研究表明，冻融循环和疲劳荷载作用均会造成CA砂浆单轴抗压强度和弹性模量的降低；先冻融循环后疲劳荷载作用下，随着冻融循环次数的增加，CA砂浆在疲劳过程中的塑性变形能显著增加，冻融10次后增幅达71.2%。同时，CA砂浆的抗压强度和弹性模量损伤幅度不断加剧，其中冻融0、5、10次的CA砂浆在疲劳2 000次后抗压强度分别降低了12.0%、16.13%、18.47%,弹性模量分别降低了10.25%、16.92%、20.96%。CT试验以及扫描电镜试验的结果表明，冻融循环会加速CA砂浆在疲劳过程中内部孔隙的劣化，加速CA砂浆在疲劳过程中裂缝的拓展与损伤的发展。更多还原

【Abstract】 To study the effects of freeze-thaw cycles and fatigue load on the performance of cement asphalt mortar(CA mortar), three damage experiments, namely single freeze-thaw cycles, single fatigue loading, and combined fatigue loading after freeze-thaw cycles, were conducted on CA mortar specimens. The changes in mortar surface morphology and final failure mode under different damage degrees, as well as the degradation laws of different parameters such as deformation curve, compressive strength, and relative elastic modulus were studied. At the same time, computer tomography(CT) was used to track the entire process of internal damage development of the specimens to explore its damage mechanism from the microscopic level. The findings show that both single freeze-thaw cycles and single fatigue loads causes a reduction in the uniaxial compressive strength and elastic modulus of CA mortar. Under the action of fatigue load after freeze-thaw cycles, with the increase in the number of freeze-thaw cycles, the plastic deformation energy of CA mortar during fatigue continuously increases. After 10 freeze-thaw cycles, the fatigue plastic deformation energy increases by approximately 71.2%. Under the action of fatigue load after freeze-thaw cycles, with the increase in the number of freeze-thaw cycles, the damage amplitudes of compressive strength and elastic modulus of CA mortar during fatigue continuously intensify. After 2 000 fatigue cycles, the compressive strengths of CA mortar with 0, 5, and 10 freeze-thaw cycles are reduced by 12.0%, 16.13% and 18.47%, respectively, and the elastic moduli are reduced by 10.25%, 16.92%, and 20.96%, respectively. The CT scanning test shows that freeze-thaw cycles lead to the degradation of internal pores in CA mortar, and accelerate the expansion and extension of cracks in CA mortar during fatigue, as well as the development of damage.更多还原