Several basic problems in stability evaluation of sliding surface of soil slopes with tension cracks
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摘要: 围绕张拉缝滑面稳定性评价中存在的若干基础性问题,通过上千个算例,系统分析了两种易混淆的“忽略”方法的可行性和适应性,以及它们在不同张拉缝深度,不同几何形状滑面、不同安全系数方法等条件下对滑面稳定性的影响,主要结论为:①张拉缝未充水时,方法一仅对简化Janbu、简化Bishop法适用,而对通用条分法GLE、不平衡推力法不适用。张拉缝考虑水压力时,方法一不适用,方法二适用。②张拉缝滑面安全系数的变化趋势曲线,与张拉缝开裂前的条间力是拉力还是压力有关,这又与黏聚力、张拉缝深度、安全系数方法相关。如果黏聚力低,则条间力大概率是压力,如黏聚力高,则条间力大概率为拉力。③张拉缝有利于迭代收敛,对于严格法GLE而言,张拉缝促进收敛的效果更明显。本文成果为科学评估张拉缝滑面的稳定性提供了坚实的理论依据和分析方法。Abstract: Focusing on some basic problems in stability evaluation of the sliding surface with tension cracks, the feasibility and adaptability of the two kinds of confusing "ignoring" methods are analyzed through over a thousand examples, and their effects on the stability of sliding surfaces with tension cracks are also investigated under different depths of tension cracks, different geometric shapes of sliding surfaces (arc, polyline, combination), different methods of safety factor. The main conclusions are drawn as follows: (1) When the tension cracks are not filled with water, the first kind of method is only applicable to the simplified Janbu and Bishop methods, but not to GLE and unbalanced thrust methods. Also, the first kind of method does not work when the water pressure is applied, only the second kind of method works. (2) The curve of the safety factor with tension cracks is related to whether the inter-slice force before cracks happen is tension or pressure, which is also related to the soil cohesion, depth of the tension cracks and methods of safety factor. If the cohesion is low, the inter-slice force is more likely to be pressure, and if the cohesion is high, the inter-slice force is more likely to be tension. (3) It's conducive to the convergence of the iterative solution by setting tension cracks in analysis, especially for the strict methods, such as GLE. The research results may provide a solid theoretical and feasible analysis method for scientifically evaluating the stability of the sliding surfaces with tension cracks.
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Keywords:
- tension crack /
- slope /
- factor of safety /
- stability /
- depth line
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表 1 组合滑面收敛情况(GLE)
Table 1 Convergence of combined sliding surface (GLE)
组合滑面 张拉缝深度/m 0 1 1.5 2 2.5 3 GLE/滑面数 1 滑面总数 265 265 264 264 263 262 2 由不收敛转收敛 — 29 39 50 54 56 3 由收敛转不收敛 — 0 0 0 0 0 4 2、3项均不收敛 70 41 30 19 14 11 -
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