Occasionally, in complex inherent characteristics of certain rocks, especially anisotropic rocks it may be difficult to measure the uniaxial compressive strength UCS. However, the use of empirical relationships to eva...Occasionally, in complex inherent characteristics of certain rocks, especially anisotropic rocks it may be difficult to measure the uniaxial compressive strength UCS. However, the use of empirical relationships to evaluate the UCS of rock can be more practical and economical. Consequently, this study carried out to predict UCS from microfabrics properties of banded amphibolite rocks using multiple regression analysis. Based on statistical results, rock microfabric parameters, which adequately represent the UCS of a given rock type have been selected. The results show that grain size, shape factor and quartz content have high significant correlation with UCS at 95% confidence level. From multiple regression model, approximately 84% of the variance of the UCS can be estimated by the linear combination of these three parameters. However, according to model performance criteria: correlation coefficient (R = 0.919), variance account for (VAF = 97%) and root mean square error (RMSE = 4.16) the study clearly indicates that the developed model is reliable to predict the UCS. Finally, this approach can be easily extended to the modeling of rock strength in the absence of adequate geological information or abundant data.展开更多
The effect of structural discontinuities on the progressive failure process of anisotropic rocks should be paid particular attention.The crack damage stress σ_(cd),also considered as the yield strength,and the relati...The effect of structural discontinuities on the progressive failure process of anisotropic rocks should be paid particular attention.The crack damage stress σ_(cd),also considered as the yield strength,and the relationship between σ_(cd) and the uniaxial peak strength σ_(ucs) of anisotropic rocks for different orientations 8 of the isotropy planes with respect to the loading directions were investigated theoretically and experimentally.A theoretical relation of σ_(cd)/σ_(ucs) with the function of the shape parameter m was established.Additionally,uniaxial compression tests of shale samples were conducted for several inclinations θ.The test result of σ_(cd)/σ_(ucs) was close to the theoretical value for a given orientation.Furthermore,both experimental results and theoretical solutions of σ_(cd)/σ_(ucs) were independent of the inclination θ while σ_(cd) andσ_(ucs) were strongly affected by θ.The strength ratio σ_(cd)/σ_(ucs) may therefore be an intrinsic property of anisotropic rocks and could be used to predict the failure of rock samples.展开更多
在论文“各向异性介质界面模式转换波Ⅰ:理论分析”给出的VTI-TTI(Transverse Isotropy with a Vertical Axis of Symmetry-Transverse Isotropy with a Tilted Axis of Symmetry)介质界面上产生的模式转换波极化系数的解析表达式和该...在论文“各向异性介质界面模式转换波Ⅰ:理论分析”给出的VTI-TTI(Transverse Isotropy with a Vertical Axis of Symmetry-Transverse Isotropy with a Tilted Axis of Symmetry)介质界面上产生的模式转换波极化系数的解析表达式和该界面反射/折射系数的计算表达式的基础上,选择各向异性页岩-泰勒砂岩界面和各向异性页岩-油质页岩界面作为界面系统,利用MATLAB进行仿真,对各向异性介质界面反射和折射特性、产生的模式转换波的极化状态以及出现的一些物理现象进行了分析和解释。使用改进后的Daley-Hron各向异性介质界面模型,分析了地层各向异性和折射TTI介质倾斜角对界面第一临界角的影响。应用能量守恒定律和声学边界条件验证了推导出的在各向异性地层界面产生的模式转换波极化系数和该界面反射/折射系数的正确性。发现某些各向异性地层界面似乎存在一个对应折射SV(Shear Vertical)波的入射临界角(第二临界角),但是在实际中并不存在的物理现象。展开更多
文摘Occasionally, in complex inherent characteristics of certain rocks, especially anisotropic rocks it may be difficult to measure the uniaxial compressive strength UCS. However, the use of empirical relationships to evaluate the UCS of rock can be more practical and economical. Consequently, this study carried out to predict UCS from microfabrics properties of banded amphibolite rocks using multiple regression analysis. Based on statistical results, rock microfabric parameters, which adequately represent the UCS of a given rock type have been selected. The results show that grain size, shape factor and quartz content have high significant correlation with UCS at 95% confidence level. From multiple regression model, approximately 84% of the variance of the UCS can be estimated by the linear combination of these three parameters. However, according to model performance criteria: correlation coefficient (R = 0.919), variance account for (VAF = 97%) and root mean square error (RMSE = 4.16) the study clearly indicates that the developed model is reliable to predict the UCS. Finally, this approach can be easily extended to the modeling of rock strength in the absence of adequate geological information or abundant data.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB10030302)the National Natural Science Foundation of China (No.41302233)the Project funded by China Postdoctoral Science Foundation (No.2014T70121)
文摘The effect of structural discontinuities on the progressive failure process of anisotropic rocks should be paid particular attention.The crack damage stress σ_(cd),also considered as the yield strength,and the relationship between σ_(cd) and the uniaxial peak strength σ_(ucs) of anisotropic rocks for different orientations 8 of the isotropy planes with respect to the loading directions were investigated theoretically and experimentally.A theoretical relation of σ_(cd)/σ_(ucs) with the function of the shape parameter m was established.Additionally,uniaxial compression tests of shale samples were conducted for several inclinations θ.The test result of σ_(cd)/σ_(ucs) was close to the theoretical value for a given orientation.Furthermore,both experimental results and theoretical solutions of σ_(cd)/σ_(ucs) were independent of the inclination θ while σ_(cd) andσ_(ucs) were strongly affected by θ.The strength ratio σ_(cd)/σ_(ucs) may therefore be an intrinsic property of anisotropic rocks and could be used to predict the failure of rock samples.
文摘在论文“各向异性介质界面模式转换波Ⅰ:理论分析”给出的VTI-TTI(Transverse Isotropy with a Vertical Axis of Symmetry-Transverse Isotropy with a Tilted Axis of Symmetry)介质界面上产生的模式转换波极化系数的解析表达式和该界面反射/折射系数的计算表达式的基础上,选择各向异性页岩-泰勒砂岩界面和各向异性页岩-油质页岩界面作为界面系统,利用MATLAB进行仿真,对各向异性介质界面反射和折射特性、产生的模式转换波的极化状态以及出现的一些物理现象进行了分析和解释。使用改进后的Daley-Hron各向异性介质界面模型,分析了地层各向异性和折射TTI介质倾斜角对界面第一临界角的影响。应用能量守恒定律和声学边界条件验证了推导出的在各向异性地层界面产生的模式转换波极化系数和该界面反射/折射系数的正确性。发现某些各向异性地层界面似乎存在一个对应折射SV(Shear Vertical)波的入射临界角(第二临界角),但是在实际中并不存在的物理现象。
