Modulus Ratio and Joint Factor Concepts to Predict Rock Mass Response

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• 作者：T. Ramamurthy ; G. Madhavi Latha ; T. G. Sitharam
• 关键词：Case studies ; Classification ; Joint factor ; Modulus ratio ; Numerical modeling ; Penetration rate of TBM ; Rock mass properties ; Standup time
• 刊名：Rock Mechanics and Rock Engineering
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：50
• 期：2
• 页码：353-366
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Geophysics/Geodesy; Civil Engineering;
• 出版者：Springer Vienna
• ISSN：1434-453X
• 卷排序：50

文摘

The commonly adopted rock mass classifications, namely RMR, Q and GSI, are used to estimate compressive strength and modulus of rock masses. These values have been examined as per modulus ratio concept, M_rj, for their reliability. The design parameters adopted in some of the recent case studies based on these classifications indicate that the M_rj values for rock masses are higher than those of the corresponding intact rocks. The joint factor, J_f, which is defined as a weakness coefficient in rock mass suggests that modulus ratio of rock mass (M_rj) has to be less than the modulus ratio of the corresponding intact rock (M_ri), on the basis of extensive experimental evidence. With joint factor, compressive strength, elastic modulus, cohesion and friction angle were estimated and applied in the analyses of a few cases. The predictions of deformations with this approach agreed well with the field measurements by adapting equivalent continuum approach. The modulus ratio concept is considered to present a unified classification for intact rocks and rock masses. Soil–rock boundary, standup time in under ground excavations and also penetration rate of TBM estimates have been linked to M_rj.