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摘要: 为提高公路黄土地区土工膜上游防渗斜墙式坝式路堤的稳定性, 分析了地震力对路堤边坡稳定性的影响, 引入地震力参数, 采用计及条块间作用力的简化毕肖普法推导出路堤边坡稳定性系数计算公式; 考虑坡面蓄水压力作用, 利用力的平衡原理得出了路堤整体稳定性判定条件。路堤边坡稳定性的计算结果表明, 地震力对坝式路堤的稳定性影响较大, 稳定性系数在考虑地震力与不考虑地震力时最小误差为0.1 (对应烈度为7°); 滑出点在坡脚外的稳定性系数远远小于坡面的稳定性系数, 边坡浸水稳定性系数小于不浸水稳定性系数, 所以边坡稳定性检算应着重考虑滑出点在坡脚外稳定性和浸水稳定性; 路堤整体稳定性计算结果表明实际沟底纵坡为2.872%时, 路堤整体是稳定的, 纵坡为10.000%时, 是不稳定的, 所以坝式路堤须设置在沟底纵坡较缓的冲沟上。Abstract: In order to improve the stability of upper slanting waterproof highway loess dam-like embankment, earthquake effect on slope stability was analyzed, the calculation formula of slope stability coefficient was deduced by introducing earthquake parameter and using simplified Bishop method, the water pressure action and mechanical balance principle of the embankment were studied, its whole stability judgment qualification was got.The calculation result of slope stability shows that earthquake effect on slope stability is great, the minimal error of slope stability coefficient is 0.1 (earthquake intensity is 7°) in the conditions of earthquake and no earthquake, relative to the slippery points out of slope bottom and on slope, the slope stability coefficient of the former is less than that of the latter, the stability coefficient value that slope is immersed in water is less than the value that slope is not immersed in water, the slippery point position, immersed state and earthquake effect must be considered when the stability is computed.The whole stability calculation result of the embankment shows that the embankment is safe when ditch gradient is 2.872%, the embankment is ruin when ditch gradient is 10.000%, so loess dam-like embankment must be built on placid ditch.
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Key words:
- subgrade engineering /
- loess dam-like embankment /
- slope /
- earthquake force /
- whole stability
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表 1 水平地震系数
Table 1. Level earthquake coefficient
设计烈度/ (°) 7 8 9 水平地震系数 0.1 0.2 0.4 表 2 上游边坡安全系数
Table 2. Safe coefficient of up-slope
地震烈度/ (°) 不考虑地震 7 8 9 状态 不浸水(坡面/坡脚外) 1.736/1.336 1.638/1.257 1.547/- 1.389/- 浸水(坡面/坡脚外) 1.576/1.125 1.479/1.063 1.388/- 1.241/- 表 3 下游边坡安全系数
Table 3. Safe coefficient of down-slope
地震烈度/ (°) 不考虑地震 7 8 9 状态 不浸水 1.752 1.645 1.552 1.390 浸水 1.608 1.506 1.418 1.262 表 4 E值计算结果
Table 4. Calculation result of E
参数 W/ (kN·m-1) α/ (°) β/ (°) g/ (m·s-2) h/m φ/ (°) c/kPa L/m E/kN 纵坡 2.872% 3 083 1.645 25 10 15 17 0.5 176 E≪0, 稳定 10.000% 4 770 5.710 25 10 15 17 0.5 218 E=57 > 0, 不稳定 表 5 最小安全系数K值
Table 5. Minimum safe coefficient K
公路规范 水利规范[8] (对应工程等级4、5级) 坝式路堤 运用条件 当高路堤对待 正常蓄水工作期 正常条件遇地震 无 K 1.25 1.25 1.10 待确定 -
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