植被作用下膨胀土渗透和力学特性及堑坡防护机制

Permeability and mechanical characteristics of expansive soil and cut slope protection mechanism under vegetation action

以广西膨胀土为研究对象,考虑植被的影响,进行了现场渗透和植被根系加筋作用力学试验,并在试验结果的基础上,对膨胀土堑坡的植被防护作用进行数值模拟。研究结果表明,植被根系的加筋作用和植被的蒸发、蒸腾作用是从两个不同的方面维持边坡稳定的,并且在降雨过程中的发挥过程有着先后的顺序。根系的加筋作用增强了土体的强度,植被的蒸发、蒸腾作用阻止了土体强度的进一步衰减。此外,植被覆盖下土体的吸湿与脱湿过程应采用不同的渗透曲线,由于植被防护在施工后未长成的一段时间内十分脆弱,所以对生长期内的植被根系力学特性进行研究具有重要意义。项目研究成果可为膨胀土地区堑坡植被防护设计和施工的发展和应用提供有益参考。

Taking the expansive soil in Guangxi as the research object,considering the influence of vegetation,field seepage test and mechanical test of vegetation root system are carried out.Based on the results of test,numerical simulation work on vegetation protection mechanism of cut slope is put forward.The results show that there are two different aspects to maintain the stability of the expansive soil slope,which are vegetation root reinforcement effect and vegetation evaporation and transpiration;and there is a successive process in rainfall to perform the protection behavior for vegetation root reinforcement effect and vegetation evaporation and transpiration.The reinforcement effect of the vegetation root enhances the strength of the soil.Vegetation evaporation and transpiration prevents the soil strength decay.Meanwhile,it is found that the soil with the vegetation covered should adopt different permeability curves in the wetting and dehumidifying process.The vegetation protection is very weak after construction because the roots will grow for a long time.So,study of the vegetation root mechanical characteristics in growth period is of great significance.Research result of this project has important reference for the development and application of design and construction for vegetation protection of expansive soil cut slope.