饱和砂岩对周期性循环载荷的动态响应
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摘要
在单轴循环加载实验中,改变平均应力和正弦波应力振幅的条件下,研究了饱和砂岩的衰减、杨氏模量和泊松比的动态响应。获得随平均应力增大杨氏模量增大,随应力振幅增大应力～应变滞回曲线向应变增大方向移动,随应力振幅减小滞回圈包含在峰值应力的滞回圈内,反映出饱和岩石记忆特性。饱和岩石随应变振幅的增大衰减增大,模量呈线性下降,泊松比呈非线性增大。在低频段,这些物理力学参数的弹性非线性特征,对研究天然地震和储层勘探,以及它们的资料解释具有现实意义。
By shifting the mean stress and the sine wave stress amplitude,uni-axial cyclic experiments were performed to study the dynamic response of fluid-saturated sandstones attenuation,Yang's modulus and Poisson's ratio.The experimental results show that the modulus increases as the mean stress increases,the stress-strain hysteresis loop moves to the increased strain as the stress amplitude increases,hysteresis loop is included in the peak stress hysteresis loop as the stress amplitude decreases,and saturated rocks have memory characteristics.The saturated rocks attenuation increases as the stress amplitude increases,the Yang's modulus linearly decreases,the Poisson's ratio nonlinearly increases.All these nonlinear elastic characteristics are very significant to the research of seismic exploration and data interpretation.
By shifting the mean stress and the sine wave stress amplitude,uni-axial cyclic experiments were performed to study the dynamic response of fluid-saturated sandstones attenuation,Yang's modulus and Poisson's ratio.The experimental results show that the modulus increases as the mean stress increases,the stress-strain hysteresis loop moves to the increased strain as the stress amplitude increases,hysteresis loop is included in the peak stress hysteresis loop as the stress amplitude decreases,and saturated rocks have memory characteristics.The saturated rocks attenuation increases as the stress amplitude increases,the Yang's modulus linearly decreases,the Poisson's ratio nonlinearly increases.All these nonlinear elastic characteristics are very significant to the research of seismic exploration and data interpretation.
引文
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[2]RICE J R.The theory of precursory processes in the in-ception of earthquake rupture.Gerlands Beitr[J].Geo-physik,1979,8(2):91.
[3]AGUSTGUDMUNDSSON.Fluid overpressure and stress drop in fault zones[J].Geophysical research letters,1999,26(1):115.
[4]SANTO D,傅文敏.利用AVO确定储层流体和弹性模量[J].石油物探译丛,1997,6:52.
[5]BIOT M A.Theory of propagation of elastic wave in a fluid saturated porous,I:Lower frequency range.II:Higher frequency range[J].J Acoust Soc Am.1956a,b,28:168.
[6]DVORKIN J,NOLEN-HOEKSEMA R,NUR A.The squirt-flow mechanicm:macroscopic description[J].Geophysics,1994,59(3):428.
[7]TUTURCU A N,PODIO A L,GREGORY A R,et al.Nonlinear viscoelastic behavior of sedimentary rocks,Part I:Effect of frequency and strain amplitude[J].Geophysics,1998,63:189.
[8]TUTUNCUN,PODIO A L,SHARMA MM.Non-linear viscoelastic behavior of sedimentary rock,partⅡ:hys-teresis effects and influence of type of fluid on elastic moduli[J].J.Geophysics,1998,63(1):195.
[9]HOLCOMB D J.Memory,relaxation,and microfracturing in dilatant rock[J].J.Geophys.Res.,1981,86(B7):6235.
[10]席道瑛,陈普刚.应力或热疲劳对花岗岩凯塞效应的影响[J].地震地质,1995,17(2):162.
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