基于水文模型模拟的边坡稳定研究

Research on slope stability based on hydrological modeling

针对传统边坡稳定研究中土体含水率在长时间序列上难于连续获得的问题,提出以水文模型VIC(variable infiltration capacity model)为工具,结合研究区降水、气温、植被覆盖等资料,输出土体含水率的逐日变化,以此作为边坡稳定分析的计算要素。结果表明:1970—2010年间,渭河流域土体含水率时空分布总体上呈增加趋势,土体抗剪强度呈降低趋势,但幅度稳定在2‰左右;基于M-C等面积圆DP3准则的强度折减法计算结果表明,边坡安全系数k在40年间有上升趋势,其中k值大于1.2的时段在85%以上,k值在1～1.2之间的时段占9%左右,k值小于1的时段占5.5%左右;土体抗剪强度时间序列R/S分析结果表明,τ-t曲线和k-t曲线Hurst系数分别为0.5568、0.5888,属于无变异;综合上述因素判断,该滑坡体现状和未来均处于稳定状态。这种方案是基于水文学角度的边坡稳定研究,为土体抗剪强度计算及地质灾害评估提供了一种新的选择。

In traditional methods for slope stability analysis,it is difficult to obtain continuous long time series of soil water content.Using the data series of precipitation,temperature and vegetation coverage in the study area,this paper develops a variable infiltration capacity(VIC)hydrological model for calculating the daily variations in soil water content that is used as a key factor in slope stability analysis.The results show that during 1970-2010,the spatial-temporal distribution of soil water content in the Wei River basin took an increasing trend,and that soil shear strength was decreased but approached a stable level at about 2‰less.Calculations of the strength reduction method based on the M-C equal-area circle DP3 criterion show that during this period,the slope stability factor k was increased,and its value of larger than 1.2 covers more than 85%of the time period,with only 9%in the range of 1.0-1.2 and 5.5%below 1.0.A R/S analysis on the soil shear strength time series reveals that the Hurst coefficients of theτ-t curve and k-t curve are 0.5568 and 0.5888,respectively,falling in the range of no variation.Based on the calculations,we conclude that the sliding bodies are stable at present and in future,and our VIC method is effective in calculations of soil water content,soil shear strength,and slope stability.