坡度及坡长对膨胀土边坡径渗流影响规律研究

Influence of slope inclination and length on runoff and seepage of swelling soil slope

在降雨条件的诱发下,膨胀土边坡常发生浅层滑坡,传统方法大多将其处理成缓坡,且认为边坡越缓越稳,但膨胀土坡却具有缓坡滑动的特性。膨胀土边坡表层含水量的变化可影响边坡浅层稳定性,而坡度和坡长等又是影响受雨后边坡表层含水量的重要因素。采用现场试验及数值模拟的方法,研究坡度及坡长对膨胀土边坡表层含水量影响规律。现场试验结果显示:膨胀土边坡坡度越陡,坡长越短,承雨面积越小时,降雨以地表径流为主,渗流为辅。通过数值模拟研究发现坡度越陡,坡长越短,越有利于边坡排水,膨胀土陡坡表层含水量可保持相对稳定的状态,由于膨胀土具低渗透性,可防止雨水进入膨胀土坡体内部而产生不利影响。研究成果表明坡度及坡长对膨胀土边坡表层含水量的影响至关重要,为解释稳定的膨胀土植绿陡坡提供佐证。

Induced by rainfall,landslides are common for the shallow layer of swelling soil slope.Traditional way of stabilizing swelling soil slopes is to make the slope inclination gentle.It was believed that the gentler the slope inclination was,the more stable the slopes could be.But it does not work for swelling soil slopes.The change in surface water content of swelling soil slope is the key factor affecting the stability of its shallow layer.In order to study the influence of slope inclination and length on the surface water content in swelling soil slopes,field tests and numerical simulation were carried out.The results show that steeper slope inclination and shorter slope length lead to smaller rain bearing area,and the rainfall mainly comes from surface runoff,while seepage is the second source.By analyzing the results of numerical simulation,it is proved that steeper slope inclination and shorter slope length contribute to better slope drainage performance.In this way,water content in steep swelling soil slope surface can stay at a relatively stable level,and can prevent rain water from permeating the slope and induce disaster.The research results show that slope inclination and length are the key factors influencing water content in shallow layer of swelling soil.It provides evidence for further study on the stability of step swelling soil slope covered by green plants.