深部岩体损伤变形特性研究
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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。
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 anastomosing
Because 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.
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。
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 anastomosing
Because 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.
引文
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[2]Gurson A L.Plastic Flow and Fracture Behavior of Ductile Materials In corporating Void Nucleation,Growth and Interaction[D].Providence:Brown University,1975.
[3]Kemeny J.Effective moduli.Non—linear Deformation and Strength of a Cracked Elastic Solid[J].Int.J.Rock Mech.Min.Sci&Georneth.Abstract.1986,23(2):107-118.
[4]王学滨,海龙,黄梅,等.岩样单轴拉伸损伤不均匀性分析[J].岩石力学与工程学,2004,23(9):1446-1449.
[5]杨更社,张长庆.岩体损伤及检测[M].西安:陕西科学技术出版社,1998.
[6]孙卫军,周维垣.裂隙岩体弹塑性一损伤本构模型[J]岩石力学与工程学报,1990,9(2):108-119.
[7]刘洋,赵明阶.岩石损伤本构理论研究综述[J].山东交通学院学报,2005,13(4):41-42.
[8]蒋斌松,韩立军.深部岩体变形的混沌预测方法[J].岩石力学与工程学报,2005,24(16):2934-2940.
[9]邓建,古德生,李勺兵.深部岩体工程随机分析方法研究[J].矿山压力与顶板管理,2005,(3):6-8.
[10]王继承,苏永华,何满朝.区间分析方法在深部岩体工程中的应用[J].岩石力学与工程学报,2005,24(21):3835-3840.
[11]蒋斌楹,蔡美峰,贺永年等.深部岩体非线形Kelvin蠕变变形的混沌行为[J].岩石力学与工程学报,2006,25(9):1862-1867.
[12]纪洪广.混凝土材料声发射性能研究与应用[M].煤炭工业出版社,北京,2004.
[13]Kaiser J.A Study of Acoustic Phenomena in Tensile Tests.[PhD Dissertation].Bristol:University of Bristol,1950.
[14]Rusch H.Physical Problems in Testing of Concrete.7Zement-Kalk-Gips(Wiesbaden),1959,12(6):5-7.
[15]Goodmen R.E.Geol.Soc.AM.Bull.,1963,74:487-490.
[16]Lochner D.A.The Role of Acoustic Emission in the Study of Rock Fracture.Int.J.Rock Mech.Min.Sci.& Geomech.Abstr.1993,30(7):883-899.
[17]K.Mogi.Study of elastic cracks caused by the fracture of heterogeneous materials and its relations to earthquake phenomena,bulletin of the Earthquake Research Institute,1962,40: 125-173.
[18](日)胜山邦久编著;冯夏庭译.声发射(AE)技术的应用[M].冶金工业出版社,1996.
[19]Goodman R.E.Geol.Soc.AM.Bull.,1963,74:487-490.
[20]Lochner D.A.The Role of Acoustic Emission in the Study of Rock Fracture.Int.J.Rock Mech.Min.Sci.& Geomech.Abstr.1993,30(7):883-899.
[21]赵方芳,利用声发射技术研究高聚物粘结炸药的损伤与断裂特性,中国工程物理研究院硕士学位论文,2000.
[22]龙湘桂,汪瑞强.岩石力学试验中的声发射测试[J].岩土工程学报,1981,3(2):69-74.
[23]陈颙,于小红.岩石样品变形时的声发射[J].地球物理学报,1984,27(4):392-399.
[24]秦四清.岩石声发射技术概论[M].西南交通大学出版社,1993.
[25]秦四清,李造鼎等.岩石声发射力学模型及其应用[[J].应用声学,1992,11(1):1-4.
[26]秦四清,李造鼎.岩石声发射事件在空间上的分形分布研究[J].应用声学,1992,11(4):19-21.
[27]唐春安.岩石声发射规律数值模拟探明[J].岩石力学与工程学报,1997,16(4):368-374.
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