【作者】 李树春；

【导师】 许江；

【作者基本信息】 重庆大学 ， 采矿工程， 2008， 博士

【摘要】 岩石在复杂荷载路径与受荷历史下的变形和损伤特性是岩石力学研究的难点,周期荷载是其中最常见也是最简单的力学现象,并且其与岩石的单调荷载方式密切相关,因此,周期荷载可以作为复杂荷载路径与受荷历史下岩石力学研究的“突破口”。选择重庆地区常见的砂岩、灰岩作为研究对象,以砂岩为主,利用西南资源开发及环境灾害控制工程教育部重点实验室(重庆大学)的MTS815岩石力学试验机、16CHs SAMOS? System声发射测试系统、中国科学院寒区旱区环境与工程研究所冻土工程国家重点实验室的CT机专用加载试验设备对单调及周期荷载作用下岩石的宏观变形及损伤特性、岩石损伤破坏过程中的声发射特性及其CT细观损伤演化规律进行了实验研究,并结合损伤力学和非线性理论进行了有益的探讨,通过以上研究,在以下方面取得一些进展:1)提出了周期荷载作用下岩石损伤破坏的四阶段规律,并在AE实验、CT实验、以及突变、分形理论分析中进行了证明和进一步说明;2)本文实验表明:岩石在低周期荷载破坏过程中出现明显的Felicity效应, Felicity比有总体下降的趋势,而且Felicity比有明显的阶段性特征。本文研究同时发现:周期荷载作用下岩石损伤过程中,定义出现“明显”声发射的标准只要在合理的范围内,并不影响Felicity比的演化趋势;3)为研究卸载时岩石的AE特性,提出了AE卸载比的概念,无论轴向应力的还是轴向应变的AE卸载比曲线都印证了周期荷载作用下岩石损伤破坏具有阶段性特征;4)岩石的种类、构造和均匀程度是AE定位实验的主要影响因素。本次砂岩AE定位实验结果显示,AE源呈散漫分布于试样中部,两端没有明显的条带丛集现象,中部没有得到声发射定位事件的“空白区”。对于此类岩石,微破裂的空间分布对主破裂的空间位置并无明显的指示意义;5)采用中国科学院寒区旱区环境与工程研究所冻土工程国家重点实验室的CT机专用加载试验设备进行了多级(两级)循环荷载下岩石损伤实时CT细观实验,实验观察到了岩样损伤演化方式的转变过程,得到了岩石损伤破坏过程中CT数、密度和标准差等参数的演化过程;6)提出损伤突变的概念,建立了以累计AE能量代表损伤的尖点突变模型,运用这一模型进行了周期荷载破坏过程和单调加载破坏过程的损伤突变分析,进一步说明了本文提出的周期荷载作用下岩石损伤破坏的四阶段规律;7)通过对单调及周期荷载下岩石AE序列的关联维分析,说明在岩石破坏过程中,其AE序列存在降维的规律;8)对某矿山露天采场边坡位移序列的监测数据表明,该边坡位移序列具有分形和混沌特征,运用混沌系统时间序列状态空间最邻近点预测方法对该边坡位移序列进行了预测。更多还原

【Abstract】 The deformation and damage of rock in the complex loading path and loading history is one of the most difficult study points on rock mechanics. Cyclic load is the most common and the simplest mechanical phenomenon, and it is related with its monotone loading manner closely. So, the study of rock under the cyclic load can be regared as‘important breakthrough jaws’of rock mechanical study in the complex loading path and loading history. This paper chooses sandstone and limestone that are common in Chongqing as study objects, mainly with sandstone, by using MTS815 Rock Mechanics Test System, 16CHs SAMOS? System and the specified loading equipment of the CT machine to do the experimental research on the deformation and damage properties, acoustic emission characteristics and CT micro-damage evolution in the process of rock damage and failure under monotonous load and cyclic load, meanwhile the paper is combined with damage mechanics and the nonlinear theory to do a hepful research. The main research work and results are as follow:1) Four phases law of rock damage failure under cyclic load have been proposed, and are proved and further explained by AE experiment, CT experiment, catastrophe theory, fractal theory;2) Experiment of this paper shows: There is obvious Felicity effect on process of rock failure under low cyclic load, the rate of Felicity is decreased in general, and the rate of Felicity has obvious characteristics of stage. The study on this paper also shows: on process of rock damage failure under cyclic load, there is no impact on the evolution trend of the rate of Felicity as long as the threshold(minimum) of obvious AE fall in a reasonable range;3) In order to study the AE Characteristics of rock during the process of unloading, this paper puts forward the concept of AE unload rate.whether AE unload rate of the axial stress or the axial strain confirm the phases character of rock damage failure under cyclic load;4) Rock types, structure and uniformity are all the main influence factors of AE location experiment. The results of Chongqing fine sandstone AE location experiment show that AE sources distribute in the central of sample, there is no obvious band and cluster grouping phenomenon on the two sides of sample, and no AE-location“blank areas”in the middle of sample. For such rock, the spatial distribution of micro-fracture is no apparent instructions significance to the spatial position of main rupture;5) By using the specified loading equipment of the CT machine from State Key Laboratory of Frozen Soil Engineering of the Chinese Academy of Sciences to do the multilevel cyclic load experimental research study, this paper observed the transformation process of rock sample damage evolution,and obtained CT number and density evolution on process of rock damage and failure under cyclic load;6) It puts forward the concept of damage mutation, establishes the cusp catastrophe model with cumulative AE energy represent damage, uses this model to analyze cusp catastrophe damage under the process of cyclic loading failure and monotonic loading failure, and further describs the four phases law of the rock damage failure under cyclic load in this paper;7) Through analyzing the correlative dimension of rock AE sequence under the monotonous load and cycle load, this paper shows that the dimension of AE sequence is decrease on the process of rock failure.8) This paper shows that the displacement sequence of this slope has characteristics of fractal and chaos by analyzing monitoring data of displacement sequence of a mine open pit slope. Using the way of the nearest neighbor of chaotic system time sequence state space, this paper forecasts the displacement sequence of this slope.更多还原