渗流作用下非饱和非均质二维边坡稳定性分析

Stability analysis of unsaturated and non-homogeneous two-dimensional slope under seepage

Terzaghi的理论土力学是以饱和土为研究对象,然而自然界的土体绝大部分为非饱和土,为了研究非饱和非均质二维边坡的稳定性,基于非饱和土强度理论,推导了一维渗流土体的重度分布规律和一维渗流土体的吸应力分布规律公式,基于极限上限分析法和旋转积分法,提出了非饱和非均质二维边坡的稳定系数的求解方法,并与前人的研究结果进行了对比验证。研究了吸力、非均质系数、坡脚角度和内摩擦角对边坡稳定性的影响。结果表明:由吸应力引起的表观黏聚力对边坡稳定性有重要影响;不同的渗流速率对细粒土边坡的稳定性有显著影响,具体表现为随着渗透系数(黏土<粉土<黄土<砂土)的增大,稳定系数逐渐减小(黏土>粉土>黄土>砂土),渗透系数与稳定系数呈负相关;考虑有效重度变化的稳定系数大于不考虑有效重度变化的稳定系数;在入渗条件和非均质系数一定的情况下,稳定系数对坡脚角度变化敏感性更高。分析结果为非饱和非均质边坡的安全评估及设计施工提供了借鉴。

Terzaghi’s theoretical geomechanics is based on saturated soils, however, the vast majority of soils in nature are unsaturated soils. To study the stability of unsaturated non-homogeneous two-dimensional slopes, based on the strength theory of unsaturated soils, this paper derives the formulas for the distribution law of heaviness of one-dimensional percolating soils and the distribution law of suction stress of one-dimensional percolating soils, and based on the limit upper limit analysis method and the rotating integral method, proposes The solution method of stability coefficient of the unsaturated non-homogeneous two-dimensional slope is proposed based on the limit analysis method and rotation integral method and is compared and verified with the results of previous studies. The effects of suction stress, non-homogeneous coefficient, slope foot angle and internal friction angle on the stability of the slope are investigated. The results show that: the apparent cohesion caused by suction stress has an important influence on slope stability;different percolation rates have a significant influence on the stability of fine-grained soil slopes, specifically,the stability coefficient decreases gradually with the increase of permeability coefficient(clay < powder < loess < sand)(clay > powder > loess > sand), and the permeability coefficient is negatively correlated with the stability coefficient;the stability coefficient considering the change of effective weight The stability coefficient is larger than that without considering the change of effective weight;under the condition of infiltration conditions and non-homogeneous coefficient, the stability coefficient is more sensitive to the change of slope foot angle. The analysis results provide a reference for the safety assessment and design construction unsaturated inhomogeneous slopes.