【作者】 万贻平；

【导师】 刘保县；

【作者基本信息】 西华大学 ， 岩土工程， 2008， 硕士

【摘要】 随着浅部资源的逐渐减少和枯竭,矿物资源地下开采的深度越来越大。深层岩体处于高温高压的复杂环境下,使得岩土工程中的地质相关的工程问题越来越突出。本文采用理论分析、实验研究相结合的方法,对深部岩体在单轴压缩、三轴压缩、围压卸荷作用下的变形、损伤破坏及声发射等相关问题进行了研究。文中对岩石试样进行了单轴压缩实验,在压缩实验的同时,使用了声发射仪器实时记录试件破坏过程中的声发射信号,加载初期有少量声发射,在荷载加至峰值载荷20%左右开始大量出现声发射活动,继续加载,裂纹扩展缓慢,声发射率较低,在外力达到峰值载荷75%左右,声发射活动显著。通过单轴压缩下岩石的应力-应变曲线研究得出:轴向应力和轴向应变的关系、损伤和应变的关系、损伤和应力的关系、声发射振幅随加载时间而变化趋势、加载时间一声发射振铃总数的关系、加载时间一声发射事件总数的关系和声发射能量随加载时间而发展变化关系。通过把岩石的声发射Count累计数作为损伤变量建立的损伤模型,并用来给出损伤的演化趋势,其结果与试验结果比较吻合。由于声发射是裂纹开展时释放出来的弹性波,声发射信号能作为衡量损伤发展的度量,本文利用三轴压缩试验进行变形和声发射分析,进一步验证了“归一化”的声发射Count累积数作为损伤变量D这一论断。并在结合声发射事件作为损伤变量的基础上,运用分段曲线损伤模型给出了损伤的演化方程,其结果与Count-时间曲线相吻合。通过卸荷不同围压及不同卸围压速率实验发现,围压卸荷的速率越小,轴向应变的变化越充分。这说明卸围压速率越低,岩体内裂隙的发展、传播及应力的转移就越有充分的时间来完成,可以产生更多的破裂面,破碎的也比较充分。反之,围压卸荷的速率越大,裂隙传播和应力转移越不充分,破裂也就更突然。同时我们从卸荷的应变-围压、应力-围压曲线图可以看出,虽然岩石试样是出自同一块岩体,但是个别岩样强度分布有一定的离散性,这应该是由于岩样的结构特征造成的。这种结构特征使得岩样局部产生较大变形,局部变形的不均匀性使得其他部位处于较复杂的应力状态,导致试验结果不同。更多还原

【Abstract】 With decreasing and exhausting of shallow resources, the mining depth of underground mineral resource is deeper and deeper.The deep rock is at complex environment at high temperature and pressure. This make the geological problems of geotechnical engineering become more and more outstanding. In this thesis, the deformation、damage and acoustic emission(AE) of deep rock due to uniaxial compression load、triaxial compression load and confining pressure unloading have been investigated with the method of a combination of experimental investigation, theoretical analysis and numerical simulation.The rock model of uniaxial compression test was carried out Meaningwhile, the AE signal at the process of compression was monitored by AE instrument as well. In the initial stages of the loading it has a few AE signs while at about 20% peak load lots of sonic emission activity appeared. Keep loading propagating of cracks become much slower and has a low emission rate simultaneously, at 75% of the peak load AE become much active.The deep rock specimens are subjected to uniaxial compression tests at the different stress and strain, the relation of damage and strain, the relation of damage and stress, the relation of loading time and AE ringing counts ,and the relation of loading time and AE energy. BY regarding AE counts and AE energy as damage variable establishing damage models and giving damage evolution tendency, we will find theory and experimentare anastomosingBecause AE is the elastic wave that the crack development releases, the AE message can take the measure of the damage development. The reasoning of regarding the "normalization" of the count as damage variable has been verifed further. With the basis of AE events and using subsection curve damage model gives out evolution equation of damage, the result consistent to the curve of count-time. With unloading different surrounding compression value and rate, we find the change of axial strain become more sufficing when the speed of unloading confining pressure becomes smaller. This prove the development transmission and transfer of rock fracture will have enough time when the speed of unloading confining pressure become smaller, and more fracture surface produced and the rock brocken even more complete. Conversely, if the speed of unloading confining pressure become bigger, fracture transmission and stress transfer become inadequacy, rupture will become abruptly.Simultaneously, we can see in the curve the distribution of rock specimen strength show discreteness, this should be come from rock structure characteristic The structure characteristic make localized rock produce large deformation, and the non-uniform of local deformation make other position of rock is at complex stress condition, that led to the result of test is different.更多还原