灰岩一维加、卸载下力学特性研究

发布时间：2018-06-17 22:09

本文选题：灰岩 + 一维加卸载　；参考：《昆明理工大学》2015年硕士论文

【摘要】：本文以国家自然科学基金项目“开挖加卸荷诱发深部巷道岩爆机理研究(51264018)”为依托,以会泽铅锌矿上向水平分层充填采矿法为工程背景,以采场“矿柱”为研究对象,根据岩体加卸载路径,对岩体进行了单轴压缩以及在不同路径下的单轴循环加卸载试验,分别从强度特征、变形特征、声发射特性及破坏模式等方面进行了采场岩体的力学特性及失稳机理研究。通过试验系统研究,主要得到以下结论：(1)通过分析应力下限恒定下分级循环加、卸载试验中各组岩样峰值强度与加卸载次数之间变化规律,利用多项式函数拟合结果表明：在恒下限循环加卸载试验中,灰岩的峰值强度是循环加卸载次数的一个一元二次函数,峰值强度随循环次数的增加而增加；(2)单轴循环加、卸载各组试验的应力—应变曲线分析研究表明：加卸载曲线互不重合,二者会形成形状多样的塑性滞回环。随循环次数的增大,各试验的滞回环面积大小呈现出一定的规律,且有不断向后“迁移”的现象产生；(3)通过对各组循环试验力学特性进行对比研究,发现单轴循环加、卸载各组试验所测灰岩峰值强度、弹性模量以及泊松比等力学参数大小受不同加卸载路径和循环次数两方面因素影响较大,且不同加卸载方式对灰岩试件首次造成的变形会直接决定灰岩的最终峰值强度大小和变形特征；(4)对各组循环试验声发射规律分析表明,当循环次数增加到试样即将破坏的前1至2次时,AE能量累计量会出现直线增大现象,声发射振铃计数也明显增多,岩样破坏瞬间会有大量的弹性能产生,说明所采灰岩脆性较大,岩爆的倾向性相对较强烈；(5)通过分析不同试验中灰岩的破坏模式并进行对比分析研究表明,一次加卸载破坏模式形式单一,分级循环加卸载和等幅值加卸载破坏模式复杂多样,揭示出不同加卸载路径对灰岩试件的破坏程度和破坏机理呈现不同特点。
[Abstract]:In this paper, based on the project of National Natural Science Foundation "Research on the mechanism of rock burst in deep roadway induced by excavation and unloading", the upward horizontal stratified filling mining method of Huize lead-zinc mine is taken as the engineering background, and the "pillar" in the stope is taken as the research object. According to the loading and unloading path of rock mass, uniaxial compression and uniaxial cyclic loading and unloading tests of rock mass under different paths are carried out. The mechanical characteristics and instability mechanism of stope rock mass are studied in the aspects of acoustic emission characteristics and failure mode. Through the systematic study, the following conclusions are obtained: (1) by analyzing the variation of the peak strength of rock samples and the loading and unloading times of each group of rock samples under constant stress lower limit, the variation law of peak strength and loading and unloading times of rock samples in each group is analyzed. The results of polynomial function fitting show that in the cyclic loading and unloading test of constant lower limit, the peak strength of limestone is a quadratic function of cyclic loading and unloading times, and the peak strength increases with the increase of cyclic times. The analysis of stress-strain curves of unloading tests shows that the loading and unloading curves do not coincide with each other, and they form plastic hysteretic loops with various shapes. With the increase of cycle times, the size of hysteresis loop area of each test presents a certain rule, and the phenomenon of continuous backward "migration" is produced. Through the comparative study of mechanical properties of each group of cyclic tests, it is found that the uniaxial cycle is added. The mechanical parameters such as peak strength, modulus of elasticity and Poisson's ratio are greatly affected by different loading and unloading paths and cycles. And the deformation caused by different loading and unloading modes for the first time will directly determine the final peak strength and deformation characteristics of limestone. When the number of cycles increases to the first one or two times before the specimen is about to be destroyed, the accumulative energy of AE will increase linearly, the number of acoustic emission ringing bells will also increase obviously, and a large amount of elastic energy will be produced at the moment of rock sample failure. It shows that the limestone mined is brittle and the tendency of rock burst is relatively strong. The failure modes of limestone in different tests are analyzed and compared with each other. The results show that the failure mode of single loading and unloading is single. The failure modes of graded cyclic loading and unloading and constant amplitude loading and unloading are complex and diverse, which reveals that different loading and unloading paths have different characteristics on the failure degree and failure mechanism of limestone specimens.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD313

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