非均质软土加筋路基三维稳定性极限上限分析

A three-dimensional upper-bound limit analysis of inhomogeneous and reinforced embankment stability

摘要:

非均质软土地区路基的稳定性问题是岩土工程中的关键技术难点,为提升对其三维稳定性问题的评估能力,基于极限上限定理构建了非均质软土加筋路基的三维基底破坏机制,并依据虚功原理建立了相应的能量守恒方程。通过引入遗传算法,开发了一种用于高效求解三维上限解的搜索方法。该三维破坏模式可退化为边坡的三维坡趾破坏形式,并与已有边坡三维上限解进行对比,以验证遗传算法的准确性与计算效率。在此基础上,开展了参数敏感性分析,考察了路基分层特征、非饱和强度特性、抗剪强度非均质性、筋材抗拉强度、铺设层数以及基质吸力等因素对加筋路基三维稳定性的影响。结果表明:在三维基底破坏模式下,非饱和软土地基与路基之间的非均质系数比对稳定性具有提升作用,且该系数比越大,路基越稳定；在筋材抗拉强度不变的条件下,减小筋材间距会削弱基质吸力对稳定性的有利影响；当铺设层数一定时,非均质性越强,筋材增强稳定性的效果越显著。该三维稳定性分析方法可为加筋参数的优化配置和复杂地基条件下的路基设计提供可靠的计算工具和理论依据。

Abstract:

The stability of embankments in regions with heterogeneous soft soils presents a key technical challenge in geotechnical engineering. To enhance the assessment of their three-dimensional (3D) stability, a 3D basal failure mechanism for reinforced embankments on heterogeneous soft soils is developed based on the upper bound limit analysis theorem, and the corresponding energy conservation equation is formulated using the principle of virtual work. A genetic algorithm is introduced to construct an efficient optimization strategy for solving the upper bound solution of 3D stability. The proposed failure mechanism is further degenerated into a 3D toe failure mode of slopes and compared with existing upper bound solutions for slopes, thereby verifying the accuracy and computational efficiency of the genetic algorithm. On this basis, a series of parametric analyses are conducted to investigate the influence of stratification characteristics, unsaturated strength properties, heterogeneous shear strength distribution, tensile strength of reinforcement, number of reinforcement layers, and matric suction on the 3D stability of reinforced embankments. The results indicate that under the 3D basal failure mechanism, a larger ratio of heterogeneity coefficients between the unsaturated subsoil and the embankment significantly improves overall stability. For a fixed reinforcement tensile strength, reducing the reinforcement spacing weakens the stabilizing effect of matric suction. When the number of reinforcement layers remains constant, the stabilizing contribution of reinforcement becomes more pronounced with increasing soil heterogeneity. The proposed 3D stability analysis method offers a reliable computational tool for optimizing reinforcement configurations and supports rational embankment design under complex foundation conditions.