Abstract：By revising the resistance coefficient, a new self-bearing capacity coefficient of rock mass is proposed in this study to evaluate the bearing capacity of rock mass, and its physical meaning is also given. A circular opening in the ideal elastic-plastic rock mass is taken as an example to derive the self-bearing capacity coefficients Kc under contraction and Ke under expansion, and parametric studies are discussed. The obtained results show that the self-bearing capacity coefficient of rock mass is a comprehensive evaluation index by multiple factors, which is significantly influenced by stress state and wall pressure, and increases with strength parameters of rock mass and the unified strength theory parameter. With the increase of the dilation parameter, the coefficient Kc decreases, whereas the coefficient Ke increases. The effects of changes in strength parameters of rock mass, intermediate principal stress and dilatancy should be fully considered in order to take full advantage of the latent potentialities of rock mass.
[1] 蒋明镜, 沈珠江. 岩土类软化材料的柱形孔扩张统一解问题[J]. 岩土力学, 1996, 17(1): 1-8. (JIANG Ming-jing, SHEN Zhu-jiang. Unified solution of expansion of cylindrical cavity for geometries with strain softening behaviour[J]. Rock and Soil Mechanics, 1996, 17(1): 1-8. (in Chinese)) [2] 栾茂田, 李波. 基于广义SMP破坏准则的柱形孔扩张问题理论分析[J]. 岩土力学, 2006, 27(12): 2105-2110. (LUAN Mao-tian, LI Bo. Theoretical analysis of cylindrical cavity expansion based on extended SMP criterion[J]. Rock and Soil Mechanics, 2006, 27(12): 2105-2110. (in Chinese)) [3] CAI G J, LIU S Y, PUPPALA A J. Assessment of soft clay ground improvement from SCPTU results[J]. Proceedings of the ICE-Geotechnical Engineering, 2012, 165(2): 83-95. [4] MARSHALL A M. Tunnel-pile interaction analysis using cavity expansion methods[J]. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 2012, 138(10): 1237-1246. [5] XU S Q, YU M H. The effect of the intermediate principal stress on the ground response of circular openings in rock mass[J]. Rock Mechanics and Rock Engineering, 2006, 39(2): 169-181. [6] SHARAN S K. Analytical solutions for stresses and displacements around a circular opening in a generalized Hoek-Brown rock[J]. International Journal of Rock Mechanics and Mining Sciences, 2008, 45(1): 78-85. [7] CHEN R, TONON F. Closed-form solutions for a circular tunnel in elastic-brittle-plastic ground with the original and generalized Hoek-Brown failure criteria[J]. Rock Mechanics and Rock Engineering, 2011, 44(2): 169-178. [8] ZHANG C G, ZHAO J H, ZHANG Q H, et al. A new closed-form solution for circular openings modeled by the Unified Strength Theory and radius-dependent Young’s modulus[J]. Computers and Geotechnics, 2012, 42: 118-128. [9] 张常光, 赵均海, 张庆贺. 基于统一强度理论的深埋圆形岩石隧道收敛限制分析[J]. 岩土工程学报, 2012, 34(1): 110-114. (ZHANG Chang-guang, ZHAO Jun-hai, ZHANG Qing-he. Convergence-confinement analysis of deep circular rock tunnels based on unified strength theory[J]. Chinese Journal of Geotechnical Engineering, 2012, 34(1): 110-114. (in Chinese)) [10] 蔡晓鸿, 蔡勇平. 水工压力隧洞结构应力计算[M]. 北京: 中国水利水电出版社, 2004. (CAI Xiao-hong, CAI Yong-ping. Structure stress calculation for hydraulic pressure tunnel[M]. Beijing: China Water Power Press, 2004. (in Chinese)) [11] 马青, 赵均海, 魏雪英. 基于统一强度理论的巷道围岩抗力系数研究[J]. 岩土力学, 2009, 30(11): 3393-3398. (MA Qing, ZHAO Jun-hai, WEI Xue-ying. Investigation of rock resistant coefficient in rocks around tunnel based on unified strength theory[J]. Rock and Soil Mechanics, 2009, 30(11): 3393-3398. (in Chinese)) [12] 朱建明, 彭新坡, 徐金海. 基于SMP准则的衬砌隧道围岩抗力系数的计算[J]. 岩土工程学报, 2011, 33(5): 700-704. (ZHU Jian-ming, PENG Xin-po, XU Jin-hai. Determination of rock resistant coefficient in lining tunnels based on SMP failure criterion[J]. Chinese Journal of Geotechnical Engineering, 2011, 33(5): 700-704. (in Chinese)) [13] 赵均海, 李爱国, 张常光. 圆形隧道弹-脆-塑性围岩自承载能力分析[J]. 中国公路学报, 2014, 27(4): 85-90. (ZHAO Jun-hai, LI Ai-guo, ZHANG Chang-guang. Self-carrying capacity of surrounding rock for a circular tunnel based on the elastic-brittle-plastic model[J]. China Journal of Highway and Transport, 2014, 27(4): 85-90. (in Chinese)) [14] 俞茂宏. 双剪理论及其应用[M]. 北京: 科学出版社, 1998. (YU Mao-hong. Twin-shear theory and its application[M]. Beijing: Science Press, 1998. (in Chinese)) [15] 俞茂宏. 岩土类材料的统一强度理论及其应用[J]. 岩土工程学报, 1994, 16(2): 1-10. (YU Mao-hong. Unified strength theory for geomaterials and its applications[J]. Chinese Journal of Geotechnical Engineering, 1994, 16(2): 1-10. (in Chinese))
