裂隙膨胀土边坡的湿热耦合特性及稳定性研究

Moisture-Heat Coupling Feature and Stability of Expansive Soil Slope with Fissures

为探究湿热耦合作用对裂隙膨胀土边坡的具体影响,将裂隙假定为无强度、无重度、渗透系数足够大的材料,建立数值分析的裂隙膨胀土边坡模型,进行时程为31 d的降雨蒸发模拟.对初始状态、干旱结束点、大暴雨结束点、二次干旱结束点和大雨结束点五个特殊时间点的温度场和湿度场进行分析,并监测全时程的安全系数变化.结论如下:坡顶和坡脚处的地表温度随时程变化分别表现为累积和消散现象,并且会在裂隙处产生一种温度“集中”效应;边坡受裂隙与下部土体渗透性差异的影响,形成局部的上层滞水现象,并对体积含水量和孔隙水压力的分布产生特殊影响;裂隙膨胀土边坡的安全系数随时程呈现先升高后降低的变化趋势,边坡的稳定性受大暴雨影响剧烈降低,并且这种降低在后续的干旱时程中持续发生.

In order to investigate the effect of moisture-heat coupling on the expansive soil slope with fissures,it was assumed that the fissures had no strength,no weight,but with sufficient permeability coefficient.Accordingly,a model of expansive soil slope with fissures was established for numerical simulation analysis to conduct rainfall and evaporation simulation for 31 days.Five special points of time were detected to analyze the temperature and humidity fields,including initial state,end of drought,end of downpour,end of the secondary drought and end of heavy rainfall,with the constant monitoring of changes in factor of safety.The corresponding conclusions are as follows.At the top and toe of the slope,the surface temperatures presented the phenomenon of accumulation and dissipation,respectively,and a temperature concentration effect was produced at the fissures.The slope was affected by the difference of permeability between the fissure and the lower soil mass,which leaded to the presence of localized perched water,thus having a special impact on the distribution of volume water content and pore water pressure.Factor of safety of the slope increased firstly and then decreased as time-histories changed.The stability of the slope was intensely reduced for the sake of downpour,and this reduction occurred continuously in the subsequent drought period.