土工格栅反包加筋支护膨胀土堑坡的工作机理

Working Mechanism of Turn-up Geogrid Reinforced Expansive Soil Cutting Slope

结合南宁外环高速修建,在完成典型南宁膨胀土性质试验后,借助FLAC3D土工格栅结构单元建立边坡模型;根据物体温度变化产生的热效应与膨胀土吸湿后的体胀效应的相似性,运用FLAC3D的热-力耦合模块分析坡体干湿循环显著影响区内的筋、土相互作用,获得反包加筋体内部的应力、变形及广义塑性应变发展规律;对比开挖边坡体内土中应力、应变及其稳定性,依据加筋膨胀土体内的筋材受力、变形特点,分析并论证了柔性支护处治膨胀土堑坡的"框箍"工作机理。

By using the geogrid structural units in FLAC3D, the slope model is established combining with the constructing practice in Nanning outer ring expressway after the accomplishment of testing the property of typical Nanning expansive soil. Based on the similarity between thermal effect of temperature variation and expansion effect of hygroscopic expansion of expansive soil, the geogrid-soil interaction in ＆T-wet cycle remarkable influence zone of the slope is analysed by thermal-mechanics coupling module in FLAC3D, and the development rule of stress, the deformation and generalized plastic strain in the turn-up geogrid flexible reinforcement expansive soil slope is obtained. According to the comparison of the stress, strain and stability of non-treated expansive soil slope, and based on the characteristics of stress and deformation of the geogrid in expansive soil slope, the ＂frame hoop＂ mechanism of flexible reinforced expansive soil cut slope is analyzed and verified.