摘要
利用电液伺服加载系统,采用单轴压缩等幅疲劳试验方式,对含预制裂隙30°、45°、60°及90°的类岩试样进行循环加载试验,借助疲劳损伤在线监测辅助试验系统、动态信号测试分析系统及超声波测试仪器对试样疲劳劣化过程进行损伤参数、轴向应变和声学参数的试验研究。研究发现:基于系统分析方法和信号处理技术,得到对损伤过程反应敏感的损伤参数A值,由A值曲线可以描述出模型试样疲劳劣化的三阶段变化规律:疲劳裂纹萌生阶段、疲劳裂纹扩展阶段及疲劳裂纹快速扩展阶段。对循环荷载作用下试样轴向应变—循环次数比曲线进行分析,可以将试样的疲劳劣化过程分为:初始变形阶段、等速变形阶段及加速变形阶段。试样超声波纵波波速随疲劳损伤的发展呈较明显的倒S形三阶段衰减规律,纵波波速随预设裂隙倾角的增大而减小。文中通过三种不同测试方法测得的试样疲劳劣化三阶段基本对应。此外,模型试样波形包络线及波形相关系数随疲劳损伤累积反应较敏感,但首波波幅变化不够稳定。研究结果可对长期交通荷载作用下的岩质边坡疲劳劣化机理及在役边坡工程服役寿命预测提供理论依据。
The electro-hydraulic servo loading system was applied and the uniaxial compression constant amplitude fatigue test was adopted to make cyclic loading tests for pre-fractured 30°,45°,60° and 90° rocklike specimens. The fatigue damage online monitoring auxiliary test system,dynamic signal test analysis system and ultrasonic wave test instrument were used to make the experimental study on the damage parameter,axial strain and acoustic parameters in the process of degradation. It was indicated,on the basis of systemic analysis method and signal processing technology,the fatigue damage parameter value A,sensitive to the process of damage,was obtained,and the value A could describe three stages of fatigue degradation variation laws of model specimens: fatigue crack initiation stage,fatigue crack propagation stage and fatigue crack rapid propagation stage. The curves between axial strain and cycle ratio under cyclic loading were analyzed,and the fatigue degradation process could be divided into: the initial deformation stage,the constant deformation rate stage and the accelerative deformation stage. The ultrasonic longitudinal wave velocity of specimens presented as obvious'inverted S'degradation laws in three stages to the development of fatigue damage,while the longitudinal wave velocity was reduced with the increase of prefractured angle. In this paper,three stages of fatigue degradation for specimens,measured by three different test methods,were basically consistent. In addition,the waveform envelope curve and waveform correlation coefficient of model specimens were relatively sensitive with the reaction of fatigue damage,but the change of head wave amplitude was not stable enough. The research results have important theoretical foundation to the fatigue degradation mechanism of rock slope under long-term traffic loading,as well as to the prediction of the service life of existing side slope engineering.
出处
《地下空间与工程学报》
CSCD
北大核心
2015年第S2期429-435,共7页
Chinese Journal of Underground Space and Engineering
基金
国家自然科学基金(41072232)
福建省自然科学基金(2015J05077)
关键词
循环荷载
含裂隙类岩试样
疲劳劣化
损伤监测
声学参数
cyclic loading
fractured rocklike specimen
fatigue degradation
damage monitoring
acoustic parameters
