Equivalent Deformation Modulus and Strength Parameters of Surrounding Rock for the Underground Powerhouse of Three Gorges Project Based on the Modified GSI System
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摘要: 基于地质强度指标GSI体系和Hoek-Brown强度准则, 研究岩体强度及变形模量时没有考虑到结构面产状对工程岩体参数的影响.结合三峡工程地下厂房, 根据围岩开挖面与结构面分布的空间位置关系, 确定了结构面分布对围岩结构等级SR的影响系数, 改进了GSI体系中围岩SR的统计方法, 确定了围岩的等效变形模量和强度参数.研究表明, 改进后的GSI体系求解的围岩弹性区等效弹性模量、扰动区等效变形模量和粘聚力分别减小了约15%、8%和28%的误差.Abstract: The influence of orientation of structure plane on parameters of rock mass is neglected in the study on the strength and deformation modulus based on geological strength index (GSI) system and Hoek-Brown strength rule. In this paper, as a case of underground powerhouse in the Three Gorges Project, the influence coefficient between the distribution of structure plane and structure rating (SR) of surrounding rock is calculated based on the space distribution character of excavated surface and structure plane; the statistical method of SR in the GSI system applied for large underground caverns is modified; and the experiential estimates of equivalent deformation modulus and strength parameters of surrounding rock are acquired. The investigations show that the calculative errors of the equivalent elastic modulus in elastic zone, deformation modulus and cohesive strength in disturbed zone of surrounding rock based on modified GSI system decreased by about 15%, 8%, 28% respectively.
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图 1 修正的定量GSI体系(Sonmez et al., 2004)
Fig. 1. Modified quantitative GSI system
图 2 体积节理数与节理面密度的关系(Palmström, 1996)
Fig. 2. The connection between joint density in a surface and volumetric joint count
表 1 岩体扰动因子D的建议值(Hoek et al., 2002)
Table 1. Proposed disturbed coefficient of rock mass
表 2 SR修正参数及结构面统计
Table 2. Modified parameters of SR and statistics of structure plane quantity
表 3 结构面性状描述
Table 3. Description for character of structure planes
表 4 结构面表面特征SCR值统计
Table 4. Statistic result of surface condition rating (SCR) of structure planes
表 5 变形模量及抗剪强度
Table 5. Deformation modulus and resisting shear strength
表 6 H-B强度参数
Table 6. Strength parameters of H-B yield rule
表 7 围岩参数反演结果
Table 7. Back analysis result of surrounding rock parameters
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