不同含水条件下板岩力学实验研究与理论分析
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摘要
以南水北调西线的板岩为研究对象,进行了不同泡水条件下的三轴压缩实验,通过引入相对吸水率的定义,分析了吸水率变化对岩石强度、弹性模量及泊松比等力学参数的影响,并从微观的角度分析了试样发生变化的机理,得出如下结论:(1)板岩在泡水后三轴抗压强度发生降低,最大降低辐度达46%左右,抗压强度随相对吸水率的变化可以用函数式来有效的描述;(2)在泡水后,板岩的弹性模量与泊松比随着吸水率的增大而增大,但由于板岩自身各向异性明显,规律性不是特别明显,只能近似用关系式来模拟;(3)理论分析证实:实际泡水条件下的岩样,在受力挤压后,会经历排水与不排水两种过程,随着吸水率的提高,弹性模量与泊松比增大,验证了实验结果;(4)利用微观力学模型初步证实:泡水后板岩颗粒的吸水性与颗粒间毛细管力的减小是造成板岩泡水后发生软化的原因。
Triaxial compression experiments of slates under different saturated conditions were done through the XTR01 electric- fluid serving compression machine, which were taken from the engineering of the western route of Water Transfer from South to North China. Relative saturation was defined as the ratio of mass of natural saturated rock to complete saturated rock; and the saturation was used to analyze the change of mechanical parameters (rock strength, elastic modulus and Poisson’s ratio). And an attempt was made to explain the change mechanism by the micro-mechanics model. With all the efforts, some conclusions are drawn as follows: 1)the triaxial compression strength of slates fell down when saturated in water and the most descendent can be 46%; and this change can be described by a law with the relative saturation; 2)when saturated, the elastic modulus and the Poisson’s ratio increased with the accretion of the relative saturation, but the law was not too clear for the anisotropy of the slates; 3)theoretical analysis has proved that the saturated rocks in geology conditions will undergo two process as drained and undrained, when the saturation increased, the elastic modulus and the Poisson’s ratio will increase simultaneously, which has confirmed the experiment results; 4)the micro-mechanical model shows that, when saturated in water, the absorbtion of the slate surface and the decrease of the capillarity among the grain are the main reasons to the water-weakening effect appeared in the slates.
Triaxial compression experiments of slates under different saturated conditions were done through the XTR01 electric- fluid serving compression machine, which were taken from the engineering of the western route of Water Transfer from South to North China. Relative saturation was defined as the ratio of mass of natural saturated rock to complete saturated rock; and the saturation was used to analyze the change of mechanical parameters (rock strength, elastic modulus and Poisson’s ratio). And an attempt was made to explain the change mechanism by the micro-mechanics model. With all the efforts, some conclusions are drawn as follows: 1)the triaxial compression strength of slates fell down when saturated in water and the most descendent can be 46%; and this change can be described by a law with the relative saturation; 2)when saturated, the elastic modulus and the Poisson’s ratio increased with the accretion of the relative saturation, but the law was not too clear for the anisotropy of the slates; 3)theoretical analysis has proved that the saturated rocks in geology conditions will undergo two process as drained and undrained, when the saturation increased, the elastic modulus and the Poisson’s ratio will increase simultaneously, which has confirmed the experiment results; 4)the micro-mechanical model shows that, when saturated in water, the absorbtion of the slate surface and the decrease of the capillarity among the grain are the main reasons to the water-weakening effect appeared in the slates.
引文
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[7]杨德军.羊湖电站引水隧洞中地下水引起的地质问题分析[J].水电站设计,2003,19(3):70-72.YANG De-jun Analysis on the geology problems causedby groundwater at Yanghu Power Station Tunnel[J].Design of Water power station,2003,19(3):70-72.
[8]葛洪魁,黄荣樽,等.三轴应力下饱和水砂岩动静态弹性参数的试验研究[J].石油大学学报,1994,18(3):41-47.GE Hong-kui,HUANG Rong-zhun.Experimental study on dynamic and static elastic parameters of water saturated sands under triaxial stresses[J].Journal of the University of Petroleum,1994,18(3):41-47.
[9]Glover P W J,Gomez J B.Damage of saturated rocks undergoing triaxial deformation using complex electrical conductivity measurements:Experimental results[J].Phys.Chem.Earth,1997,22(1-2):57-61.
[10]Gomez J B,Glover P W J.Damage of saturated rocks undergoing triaxial deformation using complex electrical conductivity measurements:mechanical modeling[J].Phys.Chem.Earth,1997,22(1-2):63-68.
[11]Newman G H.The effect of water chemistry on the laboratory compression and permeability characteristic of North Sea Chalks[J].JPT,1983,35(5):976-980.
[12]Hadizadeh J.Water-weakening of sandstone and quartzite deformed at various stress and strain rates[J].Int.J.Rock Mech.Min.Sci,1991,28(5):431-439.
[13]Delage P,Schroeder C,Cui Y J.Subsidence and capillary effects in chalks[A].Proc.Eurock’96[C].Balkema,Rotterdam:[s.n.],1996,1291-1298.
[14]Heggheim T,Madland M V.A chemical induced enhanced weakening of chalk by seawater[J].Journal of Petroleum Science and Engineering,2004,46(3):171-184.
[15]Risnes R,Haghighi H.Chalk-fluid interactions with glycol and brines[J].Tectonophysics,2003,213-226.
[16]Ernest H Rutter.The influence of temperature,strain rate and interstitial water in the experimental deformation of calcite rocks[J].Tectonophysics,1974,22:311-334.
[17]Alice Post,Jan Tullis.The rate of water penetration in experimentally deformed quartzite:implications for hydrolytic weakening[J].Tectonophysics,1998,295:117-137.
[2]刘新荣.水对岩石力学特性影响的研究[J].I M&P化工矿物与加工,2000,(5):17-20.LIU Xin-rong.Study of the effect of water to rock mechanics characteristics[J].I M&P,2000,(5):17-20.
[3]吴景浓.地壳岩石的渗透性状及孔隙水对岩石力学性质的影响[J].华南地震,1990,10(3):77-82.WU Jing-nong.Permeability of rock in crust and the influence of water at aperture on the character of rock mechanics[J].South China Seismologic Journal,1990,10(3):77-82.
[4]兰光裕.板岩的力学特征及其与超声波速的相关性分析[J].人民珠江,1997,4:16-19.LAN Guang-yu,Analysis of mechanical properties of slate rock and the relationship with the supersonic[J].Pearl River,1997,14,16-19.
[5]朱家启,安申义.龙滩水电站砂岩与板岩混合石料筑坝的工程特性研究[J].中南水电,1990,(1):12-25.ZHU Jia-qi,AN Shen-yi.Study on the engineering properties of the commixture of sand and slate rocks at Longtan Power Station[J].Central South Water Power,1990,(1):12-25.
[6]赵中波.某水电坝基工程岩石物理力学试验及探讨[J].江西有色金属,1998,12(4):4-6.
[7]杨德军.羊湖电站引水隧洞中地下水引起的地质问题分析[J].水电站设计,2003,19(3):70-72.YANG De-jun Analysis on the geology problems causedby groundwater at Yanghu Power Station Tunnel[J].Design of Water power station,2003,19(3):70-72.
[8]葛洪魁,黄荣樽,等.三轴应力下饱和水砂岩动静态弹性参数的试验研究[J].石油大学学报,1994,18(3):41-47.GE Hong-kui,HUANG Rong-zhun.Experimental study on dynamic and static elastic parameters of water saturated sands under triaxial stresses[J].Journal of the University of Petroleum,1994,18(3):41-47.
[9]Glover P W J,Gomez J B.Damage of saturated rocks undergoing triaxial deformation using complex electrical conductivity measurements:Experimental results[J].Phys.Chem.Earth,1997,22(1-2):57-61.
[10]Gomez J B,Glover P W J.Damage of saturated rocks undergoing triaxial deformation using complex electrical conductivity measurements:mechanical modeling[J].Phys.Chem.Earth,1997,22(1-2):63-68.
[11]Newman G H.The effect of water chemistry on the laboratory compression and permeability characteristic of North Sea Chalks[J].JPT,1983,35(5):976-980.
[12]Hadizadeh J.Water-weakening of sandstone and quartzite deformed at various stress and strain rates[J].Int.J.Rock Mech.Min.Sci,1991,28(5):431-439.
[13]Delage P,Schroeder C,Cui Y J.Subsidence and capillary effects in chalks[A].Proc.Eurock’96[C].Balkema,Rotterdam:[s.n.],1996,1291-1298.
[14]Heggheim T,Madland M V.A chemical induced enhanced weakening of chalk by seawater[J].Journal of Petroleum Science and Engineering,2004,46(3):171-184.
[15]Risnes R,Haghighi H.Chalk-fluid interactions with glycol and brines[J].Tectonophysics,2003,213-226.
[16]Ernest H Rutter.The influence of temperature,strain rate and interstitial water in the experimental deformation of calcite rocks[J].Tectonophysics,1974,22:311-334.
[17]Alice Post,Jan Tullis.The rate of water penetration in experimentally deformed quartzite:implications for hydrolytic weakening[J].Tectonophysics,1998,295:117-137.
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