分级循环荷载下泥岩的非线性特征参数试验

Tests on Nonlinear Characteristic Parameters of Mudstone under Cyclic Loading with Step Amplitude

通过变幅分级循环荷载试验,研究了泥岩的滞回曲线特性,荷载循环次数以及不同动应力幅值对泥岩阻尼比、动弹性模量变化规律的影响.试验结果表明,泥岩的滞回曲线特征与泥岩的黏弹性特性、塑性变形及压密的难易程度有关.加载阶段应变可能滞后或同步于应力,卸载阶段应变滞后于应力.在常幅循环加载阶段,泥岩的阻尼比与动弹性模量都会随着循环次数的增加而收敛于稳定值;在变幅分级循环加载阶段,阻尼比与动弹性模量都随动应力幅值增加呈增加的趋势.

Through the cyclic loading test with step amplitude,the characteristics of the hysteresis curve were investigated,damping ratio and dynamic elastic modulus of mudstone varying with the number of load cycles and dynamic stress amplitudes were also investigated.The test results show that the hysteresis curve characteristics of mudstone are related to the viscoelastic properties,plastic deformation and the difficulty of mudstone compaction.The strain in the loading stage may be delayed,synchronized with stress,and the strain in the unloading phase lags behind the stress.In the normal cyclic loading phase,the damping ratio and dynamic elastic modulus of mudstone converge to a stable value as the number of cycles increases.In the variable-grading and cyclic loading stage,both the damping ratio and the dynamic elastic modulus tend to increase with the increase of the amplitude of the dynamic stress.