季冻区土质路堑边坡浅层含水率变化研究

Study of regularity of variation of water content in shallow layer of soil road cutting slopes in seasonally frozen-ground region

采用现场实测和室内试验相结合的方法,研究季节性气温变化、边坡深度、坡面植物种类和坡面朝向等因素对边坡土体含水率变化的影响规律。结果证明:边坡土体冻结过程中,水分向冻结区迁移;随着冻结深度增加,含水率的变化也会向深处发展;坡面木本植物比草本植物有更明显的吸水作用;边坡含水率和土体温度的变化影响土体的强度,边坡土体温度在0℃以上时,土体强度主要受含水率变化的影响,当土体温度在0℃以下时,强度主要受温度变化的影响;三轴试验证明:边坡土体的黏聚力首先随着含水率的增加而增大,含水率达到15%以后,边坡土体的黏聚力随含水率的增大而减小;边坡土体的内摩擦角基本上是随着含水率的增大而减小。研究成果可为季节性冻土地区高等级公路路堑边坡冻融失稳的预警提供判据。

By way of combined field tests and lab tests,it was studied that the change of moisture of the soil body of the slopes with seasonal temperature,height of slope,varieties of plants on the slope surface,and specific locations of the slope,etc.It is shown that:during freezing of the soil body of the slopes,moisture moves towards the frozen zone;with deeper depth of freezing,change of water content tends to take place at deeper depth too;the herbaceous plants has better moisture absorption function than the grass family on slope surface;the strength of the soil body is affected by variation of water content of the slope and temperature of the soil body.When the temperature of the soil body of the slopes is higher than 0℃,the strength of the soil body is mainly affected by its water content.When the temperature of the soil body of the slopes is lower than 0℃,the strength is mainly affected by temperature.It is proved by triaxial test that:cohesion of the soil body of the slopes increases with increase of water content in the beginning,but starts to decrease with increase of water content when the water content reached a peak.The internal friction angle of the soil body of the slopes generally decreases with increase of water content.This study can provide basis for prevention and treatment of freeze-thaw destabilization of soil road cutting slopes of high-grade highways in seasonally frozen-ground region.