基于应力归还控制的岩石荷载速率依存性研究
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摘要
采用应力归还伺服控制方法,对I和II类岩石荷载速率依存性进行研究。首先,运用变阻器技术,实现伺服试验机应力归还控制,能对岩石峰后进行稳定控制,完整地获得岩石的全应力–应变曲线。其次,对I(田下凝灰岩、荻野凝灰岩)和II类岩石(江持安山岩、井口砂岩)进行恒定荷载速率、交替荷载速率和加载–卸载–加载组合试验,组合试验对弹性和非弹性应变成功地进行了分离,得到非弹性应变和应力的对应关系。试验结果表明,破坏强度、破坏应变、杨氏模量和破坏寿命具有明显的荷载速率特性。最后,对峰前区域的荷载速率依存性常数n提出了3种求解方法,为研究岩石的速率效应奠定了基础。
The loading rate dependence of class I and class II rocks was investigated with the stress-feedback method. This method was executed on the servo-controlled testing machine with varied-resistance technology. The complete stress-strain curves were obtained with the stress-feedback method,and the testing machine was very stable at the post-failure region. The tests under the constant loading-rate, alternate loading-rate and loading-unloading- reloading were carried out with the stress-feedback method for class I rocks(Tage tuff,Ogino tuff) and class II rocks(Emochi andesite,Jingkou sandstone) and the elastic and inelastic strains were successfully separated from the loading-unloading-reloading test. The relationship between the inelastic strain and stress was obtained. Experimental results indicate the notable loading rate dependency of strength,failure strain,Young?s modulus and failure life span. Three methods were proposed to calculate the constant n of loading rate dependence at the pre-failure region.
The loading rate dependence of class I and class II rocks was investigated with the stress-feedback method. This method was executed on the servo-controlled testing machine with varied-resistance technology. The complete stress-strain curves were obtained with the stress-feedback method,and the testing machine was very stable at the post-failure region. The tests under the constant loading-rate, alternate loading-rate and loading-unloading- reloading were carried out with the stress-feedback method for class I rocks(Tage tuff,Ogino tuff) and class II rocks(Emochi andesite,Jingkou sandstone) and the elastic and inelastic strains were successfully separated from the loading-unloading-reloading test. The relationship between the inelastic strain and stress was obtained. Experimental results indicate the notable loading rate dependency of strength,failure strain,Young?s modulus and failure life span. Three methods were proposed to calculate the constant n of loading rate dependence at the pre-failure region.
引文
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[14]HASHIBA K,FUKUI K.Index of loading-rate dependency of rock strength[J].International Journal of Rock Mechanics and Engineering,2015,48(2):859–865.
[15]HASHIBA K,OKUBO S,FUKUI K.A new testing method for investigating the loading rate dependency of peak and residual rock strength[J].International Journal of Rock Mechanics and Mining Sciences,2006,43(6):894–904.
[16]HASHIBA K,LEI M,OKUBO S,et al.Strength recovery and loading-rate dependency of fractured rock[J].Journal of the Mining and Materials Processing Institute of Japan,2009,125(9):481–488.
[17]OKUBO S,FUKUI K.An analytical investigation of a variablecompliance-type constitutive equation[J].Rock Mechanics and Rock Engineering,2006,39(3):233–253.
[18]金丰年.岩石的时间效应[博士学位论文][D].上海:同济大学,1993.(JING Fengnian.Time-depentent behaviour of rock[Ph.D.Thesis][D].Shanghai:Tongji University,1993.(in Chinese))
[19]OKUBO S,NISHIMATSU Y,FUKUI K.Complete creep curves under uniaxial compression[J].Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1991,28(1):77–82.
[20]OKUBO S,ZHANG HL K,XU J,et al.Numerical simulation on generalized relaxation of Sanjome andesite[J].Journal of the Mining and Materials Processing Institute of Japan,2014,130(8):428–433.
[21]LEI M,HASHIBA K,OKUBO S,et al.Loading rate dependency of rock in indirect tension test[C]//the 12nd Japan Symposium on Rock Mechanics and 29th Western Japan Symposium on Rock Engineering.[S.l.]:[s.n.],2008.
[2]WAWERSIK W,FAIRHURST C.A study of brittle rock fracture in laboratory compression experiments[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1970,7(5):561–575.
[3]OKUBO S,NISHIMATSU Y.Uniaxial compression testing using a linear combination of stress and strain as the control variable[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1985,22(5):323–330.
[4]PAN P Z,FENG X T,HUDSON J A.Numerical simulations of Class I and Class II uniaxial compression curves using an elasto-plastic cellular automaton and a linear combination of stress and strain as the control method[J].International Journal of Rock Mechanics and Mining Sciences,2006,43(7):1 109–1 117.
[5]BAZANT Z P,BAI S,GETTU R.Fracture of rock:effect of loading rate[J].Engineering Fracture Mechanics,1993,45(3):393–398.
[6]MA L,DAEMEN J J K.Strain rate dependent strength and stress-strain characteristics of a welded tuff[J].Bull Engineer and Geology Environment,2006,65(3):221–230.
[7]YANG J H.Effect of displacement loading rate on mechanical properties of sandstone[J].Electronic Journal of Geotechnical Engineering,2015,20(2):591–602.
[8]JEONG H S,KANG S S,OBARA Y.Influence of surrounding environments and strain rates on strength of rocks under uniaxial compression[J].International Journal of the Japanese Committee for Rock Mechanics,2008,4(1):21–24.
[9]KHAMRAT S,FUENKAJORN K.Effects of loading rate and pore pressure on compressive strength of rocks[C]//The 11st International Conference on Mining,Materials and Petroleum Engineering.[S.l.]:[s.n.],2013:11–13.
[10]OKUBO S,FUKU K,NISHIMATSU Y.Control performance of servo-controlled testing machines in compression and creep tests[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1993,30(3):247–255.
[11]OKUBO S,NISHIMATSU Y,HE C.Loading rate dependence of Class II rock behavior in uniaxial and triaxial compression tests—an application of a proposed new control method[J].International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1990,27(6):559–562.
[12]OKUBO S,GAO X J,FUKUI K.Deformation characteristics and a physical model for porous rocks under air-dried and water-saturated conditions[J].Journal of the Mining and Materials Processing Institute of Japan,2005,121(12):583–589.
[13]OKUBO S,FUKUI K,GAO X J.Rheological behaviour and model for porous rocks under air-dried and water-saturated conditions[J].The Open Civil Engineering Journal,2008,2(1):88–98.
[14]HASHIBA K,FUKUI K.Index of loading-rate dependency of rock strength[J].International Journal of Rock Mechanics and Engineering,2015,48(2):859–865.
[15]HASHIBA K,OKUBO S,FUKUI K.A new testing method for investigating the loading rate dependency of peak and residual rock strength[J].International Journal of Rock Mechanics and Mining Sciences,2006,43(6):894–904.
[16]HASHIBA K,LEI M,OKUBO S,et al.Strength recovery and loading-rate dependency of fractured rock[J].Journal of the Mining and Materials Processing Institute of Japan,2009,125(9):481–488.
[17]OKUBO S,FUKUI K.An analytical investigation of a variablecompliance-type constitutive equation[J].Rock Mechanics and Rock Engineering,2006,39(3):233–253.
[18]金丰年.岩石的时间效应[博士学位论文][D].上海:同济大学,1993.(JING Fengnian.Time-depentent behaviour of rock[Ph.D.Thesis][D].Shanghai:Tongji University,1993.(in Chinese))
[19]OKUBO S,NISHIMATSU Y,FUKUI K.Complete creep curves under uniaxial compression[J].Rock Mechanics and Mining Sciences and Geomechanics Abstracts,1991,28(1):77–82.
[20]OKUBO S,ZHANG HL K,XU J,et al.Numerical simulation on generalized relaxation of Sanjome andesite[J].Journal of the Mining and Materials Processing Institute of Japan,2014,130(8):428–433.
[21]LEI M,HASHIBA K,OKUBO S,et al.Loading rate dependency of rock in indirect tension test[C]//the 12nd Japan Symposium on Rock Mechanics and 29th Western Japan Symposium on Rock Engineering.[S.l.]:[s.n.],2008.