二维与三维边坡稳定性分析结果的比较与分析

二维与三维边坡稳定性分析得到的安全系数存在着差异，讨论这种差异与滑体几何尺寸及土体强度参数间的变化规律及其形成机制，可为合理地评价边坡稳定性分析提供理论依据。针对均质三维边坡，利用基于滑面正应力修正模式的极限平衡法分析程序，定性地讨论滑体形态、长高比、坡比、土体强度参数等指标对二维与三维安全系数计算结果差异(以F3/F2表示)的影响，总结F3/F2与影响指标间的变化规律，分析变化规律形成的内在机制。从工程应用的角度，给出需要考虑该差异影响的分界标准。研究表明，F3/F2随着长高比L/H、内摩擦角?及坡比m的增大逐渐减小，随着黏聚力c的增大逐渐增大；对于满足下列条件之一的边坡，宜采用三维安全系数来评价其稳定性，(1) L/H ≤ 5的滑坡体；(2) 5< L/H ≤ 10且 c > 25 kPa(或? < 15°，或m < 1.0) 的滑坡体。研究成果可为合理评价边坡稳定性分析方法提供参考。

Comparison and analysis of 2D and 3D slope stability analysis results

Relationships between the difference of 2D and 3D safety factor and parameters of landslide geometry (including ratio of slope, 3D sliding mass shape and length of landslide) and soil strength (including cohesion and internal friction angle) are studied. 2D and 3D safety factor of the different parameters homogeneous slopes are calculated based on the slope stability analysis program of the limit equilibrium method by modifying normal stress over slip surface. The ratio of 3D to 2D safety factor (denoted by F3/F2) is used to analyze the difference of 2D and 3D safety factor. Then, variation rule and mechanism of F3/F2 by changing parameters of landslide geometry and soil strength are also discussed. Finally, the standard of ignoring the difference of 2D and 3D safety factor are proposed from the view point of engineering practice. Results show that: F3/F2 decreases while ratio of length to height, internal friction angle and ratio of slope increases, and increases when cohesion increases; 3D safety factor is suggested to estimate the slope stability when (1) ratio of length to height is lower than or equivalent to 5; (2) ratio of length to height is more than 5 and lower than or equivalent to 10 while cohesion more than 25 kPa or internal friction angle lower than 15° or ratio of slope lower than 1. The conclusion can be referring to correct evaluation of slope stability.