循环荷载下含软弱夹层岩体声学特性试验研究

RESEARCH ON THE SWCC OF UNSATURATED NATURAL RESIDUAL SOIL

利用振动试验台系统研究循环荷载作用下含软弱夹层岩体的疲劳损伤特性,结合超声波检测仪和动态信号测试分析系统,对疲劳损伤过程中缺陷岩体声学参数进行实时的监测和细致的研究。结果表明:整个疲劳周期内,不同损伤阶段超声波波速变化最为敏感,呈倒S型衰减规律;波形在损伤过程中从近似半圆形逐渐发生畸变,波形相关性系数总体上随循环次数比的增加呈下降趋势;超声波波幅在疲劳损伤中期波动较大,频域最大幅值和主频变化特征曲线规律不明显,仅在临近破坏时才表现出快速下降趋势,无法对其真实频域特性进行有效分析和识别。最后,基于超声波波速定义损伤变量,提出以Logistic方程的逆函数形式或4次多项式方程来描述含软弱夹层岩体疲劳累积损伤演化方程。研究成果可为各类振动环境下边坡的疲劳稳定性评价和加固工程设计奠定理论基础。

By means of the vibration test system as well as the ultrasonic testing device and dynamic signal analysis system,the experiment on rock mass with weak intercalation fatigue damage are performed under cyclic loading.The acoustic parameters during defect rock fatigue damage are real-time measured and analyzed in detail. Results show that the ultrasonic wave velocity varies particularly sensitive to the fatigue cycle and reduces with an inversed S- shaped line. The waveform changes from an approximate semicircle to malformation, and the waveform correlation coefficient is descending as a whole with the cyclic times increasing. The ultrasonic wave amplitude has an intense fluctuation in the middle of the fatigue damage. And the rules of frequency-domain characteristics is not obvious,only when sample is nearly damaged,the maximum value of frequency domain and frequency declinesharply,which lead to a hard effective analysis and recognition of the frequency-domain characteristics. Finally,a damage variable is defined based on the transverse ultrasonic wave velocity and the Logistic inverse function equation and the nonlinear quartic polynomial are used to describe the growth law of rock mass with weak intercalation fatigue damage. The results may offer theoretical references for slope fatigue stability evaluation and reinforcement engineering under different kinds of vibration environment.