During the construction of an underground excavation, damage occurs in the surrounding rock mass due in large part to stress changes. While the predicted damage extent impacts profile selection and support design, the...During the construction of an underground excavation, damage occurs in the surrounding rock mass due in large part to stress changes. While the predicted damage extent impacts profile selection and support design, the depth of damage is a critical aspect for the design of permeability sensitive excavations, such as a deep geological repository(DGR) for nuclear waste. Review of literature regarding the depth of excavation damage zones(EDZs) indicates three zones are common and typically related to stress induced damage. Based on past developments related to brittle damage prediction using continuum modelling, the depth of the EDZs has been examined numerically. One method to capture stress induced damage in conventional engineering software is the damage initiation and spalling limit(DISL) approach. The variability of depths predicted using the DISL approach has been evaluated and guidelines are suggested for determining the depth of the EDZs around circular excavations in brittle rock masses. Of the inputs evaluated, it was found that the tensile strength produces the greatest variation in the depth of the EDZs. The results were evaluated statistically to determine the best fit relation between the model inputs and the depth of the EDZs. The best correlation and least variation were found for the outer EDZ and the highly damaged zone(HDZ) showed the greatest variation. Predictive equations for different EDZs have been suggested and the maximum numerical EDZ depths, represented by the 68% prediction interval, agreed well with the empirical evidence. This suggests that the numerical limits can be used for preliminary depth prediction of the EDZs in brittle rock for circular excavations.展开更多
以板裂为表现形式的岩石脆性破坏行为是深埋硬岩岩体开挖卸荷造成的典型围岩破坏现象。在简要比较4种硬岩脆性破坏数值模拟方法的基础上,基于损伤启裂-板裂界限(Damage initiation and spalling limit,DISL)模型,借助FLAC^3D开展硬岩矿...以板裂为表现形式的岩石脆性破坏行为是深埋硬岩岩体开挖卸荷造成的典型围岩破坏现象。在简要比较4种硬岩脆性破坏数值模拟方法的基础上,基于损伤启裂-板裂界限(Damage initiation and spalling limit,DISL)模型,借助FLAC^3D开展硬岩矿柱原位压缩及单轴压缩数值模拟,探讨DISL方法的适用性并进一步探究硬岩矿柱的脆性破坏过程及其特征。结果表明:原位压缩模拟中,当卸荷总时步大于某一临界数值时,矿柱两侧发生V形破坏,进而矿柱整体形成沙漏状;不同均质度下屈服破坏单元主要分布在V形破坏区内及周围,其分布范围受低围压区及张拉区范围的控制;V形剪切带主要以拉剪破坏为主,剪切带内部靠近矿柱边壁一侧,伴有张拉破坏单元;单轴压缩模拟中,峰后阶段矿柱两侧仍然产生V形破坏,并且张拉裂隙的形成范围受剪切带控制。展开更多
基金funded by the Natural Sciences and Engineering Research Council of Canadaby the Nuclear Waste Management Organization(NWMO)of Canada
文摘During the construction of an underground excavation, damage occurs in the surrounding rock mass due in large part to stress changes. While the predicted damage extent impacts profile selection and support design, the depth of damage is a critical aspect for the design of permeability sensitive excavations, such as a deep geological repository(DGR) for nuclear waste. Review of literature regarding the depth of excavation damage zones(EDZs) indicates three zones are common and typically related to stress induced damage. Based on past developments related to brittle damage prediction using continuum modelling, the depth of the EDZs has been examined numerically. One method to capture stress induced damage in conventional engineering software is the damage initiation and spalling limit(DISL) approach. The variability of depths predicted using the DISL approach has been evaluated and guidelines are suggested for determining the depth of the EDZs around circular excavations in brittle rock masses. Of the inputs evaluated, it was found that the tensile strength produces the greatest variation in the depth of the EDZs. The results were evaluated statistically to determine the best fit relation between the model inputs and the depth of the EDZs. The best correlation and least variation were found for the outer EDZ and the highly damaged zone(HDZ) showed the greatest variation. Predictive equations for different EDZs have been suggested and the maximum numerical EDZ depths, represented by the 68% prediction interval, agreed well with the empirical evidence. This suggests that the numerical limits can be used for preliminary depth prediction of the EDZs in brittle rock for circular excavations.
文摘以板裂为表现形式的岩石脆性破坏行为是深埋硬岩岩体开挖卸荷造成的典型围岩破坏现象。在简要比较4种硬岩脆性破坏数值模拟方法的基础上,基于损伤启裂-板裂界限(Damage initiation and spalling limit,DISL)模型,借助FLAC^3D开展硬岩矿柱原位压缩及单轴压缩数值模拟,探讨DISL方法的适用性并进一步探究硬岩矿柱的脆性破坏过程及其特征。结果表明:原位压缩模拟中,当卸荷总时步大于某一临界数值时,矿柱两侧发生V形破坏,进而矿柱整体形成沙漏状;不同均质度下屈服破坏单元主要分布在V形破坏区内及周围,其分布范围受低围压区及张拉区范围的控制;V形剪切带主要以拉剪破坏为主,剪切带内部靠近矿柱边壁一侧,伴有张拉破坏单元;单轴压缩模拟中,峰后阶段矿柱两侧仍然产生V形破坏,并且张拉裂隙的形成范围受剪切带控制。
