循环荷载的频率和幅值对砂岩动力特性的影响  

Effects of frequency and amplitude of cyclic loading on the dynamic characteristics of sandstone

作　　者：邓华锋[1] 胡玉[1] 李建林[1] 王哲[1] 张小景[1] 张恒宾 

机构地区：[1]三峡大学三峡库区地质灾害教育部重点实验室,湖北宜昌443002

出　　处：《岩土力学》2017年第12期3402-3409,3418,共9页Rock and Soil Mechanics

基　　金：国家自然科学基金资助项目(No.51439003;No.51679127);水利部公益性科研专项经费项目(No.201401029);湖北省自然科学基金重点项目(No.2015CFA140);三峡大学研究生科研创新基金(No.2015CX)~~

摘　　要：岩体动力参数的取值关系到岩体结构工程动力计算结果是否符合工程实际。鉴于实际动力荷载的频率和幅值都可能在一定范围内变化,设计了综合考虑频率和幅值变化的循环加、卸载试验方案,分析这两种因素对砂岩动应力-应变滞回曲线、动弹性模量、阻尼比和阻尼系数等动力参数的影响。研究结果表明:(1)应力-应变滞回圈的形态与加卸载的频率和幅值有关,频率越大则越饱满,幅值越大则越狭长;(2)循环荷载频率从0.02 Hz增至1.00 Hz,砂岩的阻尼系数逐渐减小,而阻尼比和动弹性模量逐渐增大,比较而言,阻尼比和阻尼系数变化幅度较大,动弹性模量的变化幅度较小;(3)循环荷载应力幅从10 MPa增至35 MPa时,砂岩的阻尼比逐渐减小,阻尼系数变化不大,而动弹模逐渐增大,比较而言,应力幅对动弹性模量的影响较大。研究成果可为岩石动力参数的合理选取提供较好的参考。The values of rock dynamic parameters directly influence the results of dynamic calculation in rock structural engineering, which shall be validated with the results obtained from practical engineering projects. As the frequency and amplitude of actual dynamic loading could change within a specific range, a series of cyclic loading and unloading experiments was conducted by considering the variations of these two factors. The effects of these two factors on the dynamic characteristics of sandstone were analysed, such as dynamic stress-strain hysteresis curve, dynamic elastic modulus, damping ratio and damping coefficient. The results showed that the shape of stress-strain hysteresis loop was closely related to the frequency and amplitude of cyclic loading and unloading. It was found that the higher the frequency was, the plumper the hysteresis loop was, and the greater the cyclic loading amplitude was, and the narrower the hysteresis loop was. When the frequency of cyclic loading increased from 0.02 Hz to 1.00 Hz, the damping coefficient of sandstone gradually decreased, whereas the damping ratio and dynamic modulus slowly increased. The varying ranges of damping coefficient and damping ratio were relatively larger, while the growth range of dynamic elastic modulus was smaller. When the stress amplitude of cyclic loading increased from 10 MPa to 35 MPa, the damping ratio of sandstone gradually decreased, whereas the damping coefficient slightly changed and the dynamic elastic modulus slowly increased. However, the effects of stress magnitude on the dynamic elastic modulus were more significant. Therefore, this study can provide useful references for reasonably selecting dynamic parameters of rock mass.

关 键 词：循环荷载 频率 应力幅 阻尼比 阻尼系数 动弹性模量 

分 类 号：TU452[建筑科学—岩土工程]