STUDY ON INFLUENCE FACTORS OF STABILITY AND FAILURE MODES OF ANTI-DIP ROCK SLOPE WITH SOFT AND HARD INTERBED
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摘要: 反倾边坡破坏会诱发严重的地质灾害,因此对软硬互层反倾岩质边坡的稳定性及破坏模式进行研究具有重要的意义。本文基于数值模拟的方法,利用离散元UDEC软件,首先基于正交试验设计法,考虑了边坡坡角、岩层倾角、坡高、相邻软硬岩层总厚度、硬软岩层厚度比、硬软岩层力学参数序号比、结构面力学参数7个因素的影响,设计了32组正交试验,利用强度折减法对边坡的稳定性及可能的破坏模式进行模拟,并从边坡稳定系数和位移两个方面对计算结果进行敏感性分析。结果表明,边坡坡角和岩层倾角对稳定系数影响较大,结构面力学参数和坡高对边坡位移影响较大;然后对边坡的破坏模式进行归纳总结,将软硬互层反倾边坡的破坏模式分为弯曲倾倒破坏、坍塌滑动破坏和块体倾倒破坏3种类型,并对每种破坏类型的边坡特征进行详细分析。Abstract: The failure of anti-dip slopes can induce serious geological disasters, so it is of great significance to study the stability and failure modes of anti-dip rock slopes with soft and hard interbed. This paper is based on numerical simulation method and uses discrete element software UDEC. Firstly, this paper takes into account the influence of the slope angle, rock inclination angle, slope height, total thickness of adjacent soft and hard rock layers, thickness ratio of hard and soft rock layers, ratio of mechanical parameter number of hard and soft rock layers, and the mechanical parameters of structural plane. Then based on orthogonal experimental design method, this paper designs 32 sets of orthogonal tests to simulate the stability of the slope and possible failure modes by the strength reduction method. The sensitivity analysis is conducted from two aspects of slope safety factor and displacement. It is found that the slope angle and rock inclination angle have a great impact on the safety factor, and the mechanical parameters of structural plane and slope height have a great impact on the slope displacement. Then the failure modes of anti-dip rock slope with soft and hard interbed are summarized and divided into three types: bending-dumping, collapse-sliding and block-dumping failures.The characteristics of each failure modes are analysed in detail.
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Key words:
- Anti-dip slope /
- Soft and hard interbed /
- Numerical simulation /
- UDEC /
- Orthogonal test
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表 1 岩层力学参数选取
Table 1. Selection of mechanical parameters of rock
序号 重度γ/kN·m-3 内摩擦角φ/(°) 黏聚力c/MPa 弹性模量E/GPa 泊松比μ 抗拉强度T/MPa 1 22.5 27 0.20 1.30 0.350 0.10 2 23.5 33 0.45 3.65 0.325 0.22 3 25.5 45 1.10 11.00 0.275 0.60 4 26.5 50 1.50 16.00 0.250 0.80 表 2 结构面力学参数选取
Table 2. Selection of mechanical parameters of structural plane
序号 剪切模量Jks/GPa 体积模量Jkn/GPa 摩擦角Jfri/(°) 黏聚力Jcoh/MPa 抗拉强度Jten/MPa 1 1 1 10 0.01 0.01 2 30 30 20 0.03 0.03 3 60 60 30 0.06 0.06 4 90 90 40 0.09 0.09 表 3 硬软岩层力学参数序号组合
Table 3. Combination of mechanical parameter number of hard and soft rock layers
硬软岩层力学参数序号比λ 硬岩序号 软岩序号 1.5 3 2 2 4 2 3 3 1 4 4 1 表 4 正交试验设计表
Table 4. Orthogonal test table
试验编号 坡角α/(°) 岩层倾角β/(°) 坡高h/m 相邻软硬岩层总厚度D/m 硬软岩厚度比η 硬软岩层力学参数序号比λ 结构面参数(以Jfri为代表)/(°) 1 60.00 45.00 40.00 6.00 0.50 1.50 20.00 2 75.00 60.00 80.00 6.00 0.50 4.00 30.00 3 45.00 30.00 40.00 2.00 0.50 4.00 30.00 4 45.00 30.00 100.00 4.00 0.50 3.00 20.00 5 75.00 30.00 80.00 2.00 2.00 2.00 20.00 6 30.00 75.00 60.00 4.00 0.50 2.00 30.00 7 45.00 60.00 40.00 6.00 1.00 2.00 20.00 8 45.00 75.00 60.00 6.00 0.50 3.00 10.00 9 60.00 30.00 60.00 6.00 2.00 4.00 10.00 10 75.00 60.00 60.00 1.00 0.50 3.00 20.00 11 60.00 45.00 100.00 1.00 0.50 2.00 30.00 12 30.00 30.00 40.00 1.00 0.50 1.50 10.00 13 45.00 45.00 80.00 4.00 2.00 2.00 10.00 14 60.00 75.00 40.00 2.00 2.00 3.00 30.00 15 75.00 45.00 40.00 4.00 0.50 4.00 40.00 16 30.00 60.00 40.00 4.00 2.00 3.00 40.00 17 60.00 60.00 80.00 4.00 0.50 1.50 10.00 18 75.00 45.00 100.00 2.00 0.50 3.00 10.00 19 60.00 30.00 80.00 1.00 1.00 3.00 40.00 20 30.00 75.00 80.00 2.00 0.50 1.50 20.00 21 60.00 75.00 100.00 4.00 1.00 4.00 20.00 22 45.00 45.00 60.00 2.00 1.00 1.50 40.00 23 75.00 30.00 60.00 4.00 1.00 1.50 30.00 24 45.00 75.00 80.00 1.00 0.50 4.00 40.00 25 30.00 45.00 60.00 1.00 2.00 4.00 20.00 26 45.00 60.00 100.00 1.00 2.00 1.50 30.00 27 30.00 30.00 100.00 6.00 0.50 2.00 40.00 28 75.00 75.00 40.00 1.00 1.00 2.00 10.00 29 30.00 45.00 80.00 6.00 1.00 3.00 30.00 30 60.00 60.00 60.00 2.00 0.50 2.00 40.00 31 75.00 75.00 100.00 6.00 2.00 1.50 40.00 32 30.00 60.00 100.00 2.00 1.00 4.00 10.00 表 5 稳定系数的极差分析结果
Table 5. Range analysis results of safety factor
平均值 α β h D η λ Jfri k1 5.19 4.59 4.13 4.20 3.37 4.07 2.81 k2 4.20 4.23 4.05 3.81 3.70 4.00 3.52 k3 2.93 3.38 3.28 3.14 4.27 2.76 3.59 k4 2.39 2.52 3.25 3.57 — 3.89 4.79 R 2.80 2.07 0.87 1.07 0.89 1.31 1.99 敏感性 α>β>Jfri>λ>D>η>h 表 6 稳定系数的方差分析结果
Table 6. Variance analysis results of safety factor
源 III类平方和 自由度 均方 F 显著性 修正模型 98.687a 20 4.934 8.158 0 截距 411.143 1 411.143 679.713 0 坡角α 38.214 3 12.738 21.059 0 岩层倾角β 20.597 3 6.866 11.350 0.001 坡高h 5.414 3 1.805 2.983 0.078 相邻软硬岩层总厚度D 4.781 3 1.594 2.634 0.102 硬软岩层厚度比η 4.240 2 2.120 3.505 0.066 硬软岩层力学参数序号比λ 9.151 3 3.050 5.043 0.019 结构面参数Jfri 16.290 3 5.430 8.977 0.003 误差 6.654 11 0.605 总计 538.035 32 修正后总计 105.340 31 a. R 方=0.937(调整后R 方=0.822) 表 7 32组边坡潜在破坏模式特征归纳
Table 7. Summary of potential failure modes of 32 groups of slopes
破坏模式 试验编号 边坡特征 弯曲倾倒 1、2、5、6、7、8、9、10、13、15、17、18、20、21、23、30、32 ①坡角较大,倾角较大,其中坡角与倾角之和均大于90°;②软岩厚度占比较大,硬软岩厚度比大多为0.5;③岩体和结构面强度参数较小 坍塌滑动 3、4、11、12、19、22、25、26 ①倾角较小,大多小于45°,高度较高;②软岩厚度占比较大,硬软岩厚度比大多为0.5,层厚较小,多为1m;③岩体强度和结构面参数较小 块体倾倒 14、16、24、27、28、29、31 ①坡角较大,坡高较低,多为80m以下;②倾角较大,大多大于60°;③硬岩厚度占比较大且岩体强度参数较大 -
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