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为了提高雨水软化条件下路基土质边坡稳定性分析的准确性,开展路基土质边坡失稳模式及其判别准则分析,提出边坡失稳随软化深度wz增加依次呈现单位土条式、组合式及整体式3种模式;采用滑体长度L与软化深度z_w的比值λ作为表征参数,确立界定3种失稳模式的2个阈值λ_(cr)和λ_f;基于刚体极限平衡条件,构建以组合式失稳模式为基础且涵盖3种失稳模式的边坡稳定安全系数统一表达式。研究表明:单位土条式与组合式失稳模式转化阈值λ_(cr)和组合式与整体式失稳模式转化阈值λ_f受坡体强度参数及几何参数影响并不显著,范围分别为15.2~20.0和3.0~6.3;λ<λ_(cr)时采用单位土条式顺坡平面失稳模式忽略滑体上下缘滑体力学作用会得到偏于保守的结果,λ>λ_f时采用以圆弧滑面为代表的整体式曲面失稳模式则偏于危险,而λ≤λ_f时采用对数螺旋形和圆弧形的整体式曲面滑动模式差异不大。
In order to improve the accuracy of subgrade slope stability analysis under rainwater softening conditions and to carry out subgrade soil slope instability model and criterion analysis, it is proposed that the slope instability increases with the softening depth wz, followed by the unit soil strip type, combined type And the monolithic three modes. The ratio λ of the slide length L and the softened depth z_w is used as the characterization parameter to establish two thresholds λc (cr) and λ_f which define the three kinds of instability modes. Based on the rigid body limit equilibrium condition, Based on the instability mode and covers the unified expression of slope stability safety coefficient of three kinds of instability modes. The results show that the conversion threshold λ cr of combined soil and composite instability mode and the transition threshold λ f of combined and total instability mode are not significantly affected by the slope strength parameters and geometric parameters, ranging from 15.2 to 20.0 And 3.0 ~ 6.3; λ <λ_ (cr) when using units of soil slope downhill plane instability mode sliding body slip on the lower edge of the body will be biased to a conservative result, λ> λf when the use of arc slip surface As the representative of the monolithic surface instability mode is a little dangerous, and when λ≤λ_f using logarithmic spiral and arc-shaped monolithic surface sliding mode is not different.