循环荷载作用下应力速率与应变速率不同步研究

发布时间：2019-02-27 16:34

【摘要】：为深入研究循环加卸载作用下岩体的变形规律,针对三峡库区砂岩进行了56组循环加卸载试验。根据试验的不同步现象,对应力应变滞后概念进行修正:(1)应力超前于应变和应力滞后于应变现象共存,故将"应力应变滞后现象"更名为"应力应变不同步现象"更为合理;(2)在应力应变不同步现象的基础上,应考虑应力速率应变速率的不同步现象。通过分析循环加卸载试验的不同步机制,提出应力应变吸引点、应力速率应变速率吸引点、应力应变补偿机制和应力速率应变速率补偿机制4个概念,并且得到:应力应变同步与应力速率应变速率同步不能同时出现;不同步现象是必然而同步仅存在于某一时刻点;应力应变处于螺旋式循环递进的过程。基于循环加卸载试验,首次发现应力速率应变速率不同步现象,在不同步现象中提出了3个不同步阶段的定义,并通过分析预测变形速率实际变形速率、表观弹性模量以及岩样的瞬时泊松比随时间的变化规律,提出3种对不同步阶段定量判别的方法。此外,基于同频率不同峰值强度下试验得到,随着峰值强度f(t)的增加,岩样的E(t)值逐渐增加,式E(t)?af(t)?b吻合度也逐渐增加。
[Abstract]:In order to study the deformation rule of rock mass under cyclic loading and unloading, 56 groups of cyclic loading and unloading tests were carried out for sandstone in the three Gorges Reservoir area. According to the phenomenon of out-of-synchronization, the concept of stress-strain lag is modified: (1) stress is ahead of strain and stress-lag is coexisting with strain; Therefore, it is more reasonable to change the name of "stress-strain lag phenomenon" to "stress-strain out-of-sync phenomenon". (2) the stress rate and strain rate should be taken into account on the basis of stress-strain asynchronous phenomenon. By analyzing the asynchronous mechanism of cyclic loading and unloading test, four concepts are put forward: stress / strain attraction point, stress rate / strain rate attraction point, stress / strain compensation mechanism and stress rate / strain rate compensation mechanism. The results show that the synchronization of stress-strain and stress-rate-strain can not occur at the same time. The phenomenon of out-of-sync is inevitable, and synchronization only exists at a certain point of time, and the stress and strain are in the spiral cycle progressive process. Based on cyclic loading and unloading tests, the phenomenon of stress rate / strain rate dissynchronism is found for the first time. In this paper, the definition of three out-of-sync stages is put forward, and the deformation rate / actual deformation rate is predicted by analyzing and predicting the deformation rate. Based on the variation of apparent elastic modulus and instantaneous Poisson ratio of rock samples with time, three methods for quantificationally discriminating out-of-sync stage are proposed. In addition, based on the same frequency and different peak intensity, it is found that with the increase of peak intensity f (t), the E (t) value of rock samples increases gradually, and the E (t)? af (t)? b coincidence also increases gradually.
【作者单位】：三峡大学三峡库区地质灾害教育部重点实验室;三峡大学土木与建筑学院;
【基金】：国家科技支撑计划项目(2015BAB07B08) 国家自然科学基金资助项目(51579138) 长江科学院开放研究基金资助项目(CKWV2016377/KY)~~
【分类号】：TV223

【共引文献】