基于SWCC试验数据的坝体非饱和非稳态渗流与稳定性研究

饱和-非饱和状态是土存在于自然界的真实状态,描述和解释这种状态的非饱和土力学理论在土石坝渗流、污染物传输、冻土渗流相变、边坡和路基稳定性分析等领域有着广泛的应用。非饱和土的土水特征曲线(SWCC)是非饱和土力学研究的基本内容之一,对非饱和土体渗流和稳定性分析至关重要。采用Python语言开发了非饱和渗流与稳定性分析软件包USSA和非饱和土土水特征曲线试验数据处理和模型拟合界面。对非饱和土的土水特征曲线数据进行处理,以模型拟合参数作为基本输入进行非饱和渗流场的模拟,再到非饱和土的稳定性分析,详细呈现了非饱和土渗流与稳定性分析及软件开发的全过程。基于SWCC模型的拟合参数对坝体渗流稳定性进行了分析,分析结果表明水位变化过程中坝体两侧斜坡具有明显不同的稳定性演化规律。当采用有限元强度折减法进行非饱和土斜坡稳定性分析时,最终安全系数为所有边坡安全系数演化曲线的最低包络线。

UNSATURATED TRANSIENT FLOW IN DAM AND ITS STABILITY ANALYSIS USING SWCC EXPERIMENTAL DATA

Saturated-unsaturated state is a natural state of soils. Hence, unsaturated soil mechanics has wide applications in seepage analysis of earth and rockfill dam, contaminant transport, seepage and phase transform of frozen soil, and stability analysis of slope and embankment. As a fundamental relationship, the soil-water characteristic curve(SWCC)plays an essential role in the research of unsaturated soil mechanics. Python language is employed to develop the unsaturated seepage and stability analysis(USSA)software as well as the graphic user interface(GUI)for data processing and data fitting of SWCC curve. Based on a practical slope example, the whole analyzing process is described in details. It is from the data processing and data fitting of SWCC curve to unsaturated seepage analysis and stability analysis. The stability of dam under unsaturated seepage is conducted using the fitted parameters of SWCC model. The numerical results show that the stability evolutions of two dam slopes are quite different under the changing process of water level. When applying the shear strength reduction finite element method to the slope stability of unsaturated soil, the final FOS appears to be the lowest envelope of those FOS curves of all slopes.