持续蒸发作用下膨胀土裂隙和湿热特性室内模型试验

以广西白色强膨胀土为研究对象,对有、无植被覆盖和农膜覆盖的膨胀土分别进行30 d持续蒸发试验,研究持续蒸发过程对膨胀土湿热和裂隙拓展特性的影响。结果表明,无植被覆盖时表层土体脱湿量及脱湿速率分别为7.38%和0.17%/d,植被覆盖时分别为5.29%和0.07%/d,显然植被覆盖的脱湿量和脱湿速率均小于无植被覆盖的,而农膜覆盖土体蒸发受到遏制,水分无散失;无植被覆盖和农膜覆盖土体平均温度变化分别是7.36℃和9.72℃,比植被覆盖的2.03℃大5⁸℃,可见植被覆盖降低了土体温度变化幅度;无植被覆盖土体裂隙深度达32 cm,与湿热影响深度28 cm较接近;植被覆盖和农膜覆盖土体平面及竖向均无出现明显裂隙,植被覆盖和蒸发受到遏制的状态可阻止土体裂隙开展。

Laboratory model test on fissure development and moisture-heat behavior of expansive soil under action of continuous evaporation

Talking the strong expansive soil of Guangxi as research object. 30 days evaporation experiment was respectively carried out for expansive soil with on without vegetation cover and under plastic sheeting cover, to explore the influence of continuous evaporation process on moisture-heat behavior and fissures development. The results show that without vegetation cover, the surface soil amount and rate of volumetric water content changes respectively are 7.38% and 0.17%/d; with vegetation cover, which are respectively 5.29% and 0.07%/d; apparently under vegetation cover, whose dehydration content and drying rate were less than that of without vegetation cover. For plastic sheeting cover, expansive soil evaporation is curbed and no water loss. Without no vegetation and plastic sheeting cover, the average temperature changes of expansive soil are 7.36 ℃，9.72 ℃ respectively, which is 5-8 ℃ higher than that with vegetation cover 2.03℃; obviously, the vegetation cover reduces expansive soil temperature variation. Without vegetation cover, expansive soil fissure depth is up to 32 cm, which is closer to 28 cm influence depth of moisture-heat. Under vegetation and plastic sheeting cover, no apparent fissure carried out in the plane and vertical; vegetation cover and the state of evaporation curbed can prevent expansive soil fissure developing.