Characteristics of strength reduction in the weak layer and large-slip displacement of the cut slope on the Fushun west open-pit mining area
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摘要: 软弱夹层的强度衰减特性是顺层岩质边坡失稳的关键因素之一。选取抚顺西露天矿南帮边坡为研究对象,通过UDEC数值模拟方法,结合离散元理论,建立南帮顺层边坡二维离散元模型,开展南帮边坡弱层强度衰减特性及滑坡大变形规律研究。通过不同围压下的三轴试验,拟合得到弱层残余强度随时间衰减曲线,并通过FISH语言实现数值计算过程中弱层强度随拟合方程进行衰减。数值模拟结果表明:坡脚处最先产生变形,随着开挖的不断进行,弱层强度逐渐衰减,坡顶后缘被拉裂,原有应力平衡被破坏,滑坡体沿弱层产生滑动。通过建立回填数值模型进行边坡稳定性得知,采取压脚回填100 m以后,边坡稳定系数得到了明显的提高,边坡处于基本稳定状态。Abstract: The strength attenuation characteristics of the weak interlayers are one of the key factors leading to instability of the bedding rock slopes. In this study, the Nanbang slope of Fushun West Open-pit Mine was selected as the research object. A two-dimensional discrete element model of the Nanbang bedding slope was established using the UDEC numerical simulation method in combination with the discrete element theory, and the strength attenuation characteristics and large deformation law of the weak layer were studied. The residual strength decay curve of the weak layer over time was obtained by fitting the results of triaxial tests conducted under different confining pressures, and the FISH language was used to implement the attenuation of weak layer strength during numerical calculations according to the fitting equation. The numerical simulation results showed that deformation first occurred at the toe of the slope. As excavation continued, the strength of the weak layer gradually decreased, resulting in the trailing edge of the slope top being pulled apart, and the original stress balance being destroyed. Eventually, the landslide body slides along the weak layer. By establishing a backfilling numerical model for slope stability, it was found that after backfilling with a presser foot for 100m, the slope stability coefficient had significantly improved, and the slope was in a basically stable state.
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Key words:
- layered slope /
- numerical simulation /
- discrete element /
- weak interlayer /
- Strain softened
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表 1 弱层强度拟合参数
Table 1. Fitting parameters for weak layer strength
目标参数 a b c R2 残余强度 0.15736 0.81446 0.6931 0.99969 峰值强度 0.17003 0.34714 4.89517 0.99155 表 2 岩体力学参数
Table 2. Summary table of rock mechanical parameters
岩性 密度
/(kg.m−3)弹性模量
/GPa泊松比 抗剪断强度 内摩擦角 黏聚力/MPa 玄武岩 2800 7 0.14 42 0.3 花岗片麻岩 2800 8 0.2 45 0.4 弱层 2300 0.1 0.4 16.9 0.075 煤层 1300 1.2 0.24 35 0.14 油母页岩 2300 3.4 0.26 35 0.2 断层 2300 0.1 0.4 16.9 0.075 杂填土 1800 0.1 0.4 18 0.1 凝灰岩 2600 8 0.25 39 0.25 表 3 节理力学参数
Table 3. Summary table of joint mechanical parameters
岩性 刚度参数 抗剪断强度 法向刚度
/(GP·am−1)切向刚度
/(GPa·m−1)节理面摩擦角 节理面黏聚力
/kPa玄武岩 3.33 3.33 25 90 花岗片麻岩 5.93 5.93 45 150 弱层 1.81 1.81 20 10 煤层 2.43 2.43 25 40 油母页岩 2.77 2.77 25 40 断层 1.81 1.81 20 10 凝灰岩 3.67 3.67 28 100 表 4 滑坡稳定状态划分
Table 4. Division of landslide stable state
滑坡稳定系数 F<1.00 1.00≤F<1.05 1.05≤F<1.15 F≥1.15 滑坡稳定状态 不稳定 欠稳定 基本稳定 稳定 -
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