基于离心模型试验的软土地基路堤加筋垫层效应研究

Research of Effect of Reinforced Cushion of Soft Soil Subgrade Embankment Based on Centrifugal Model Tests

为了考察软土地基路堤的加筋垫层效应,进行4组不同垫层结构处理软土地基的离心模型试验,测试软土地基的沉降变形、垫层拉力和路堤基底压力等数据。测试数据表明:设置加筋垫层能有效减小并匀化软土地基在上部路堤荷载作用下的沉降变形,约束地基水平变形,且刚性垫层的效果好于柔性垫层;柔性垫层具有一定的匀化路堤基底压力的能力,基底压力的分布与垫层结构形式及路堤荷载的大小相关;随路堤荷载的增加,刚性垫层的水平拉力呈M形分布,柔性垫层筋带拉力由M形分布逐渐过渡为"锅底"状分布,若忽略地基的摩擦力,刚、柔性垫层中路肩下拉力可分别用静止土压力公式和朗肯主动土压力公式估算。

Four groups of centrifugal model tests with different types of cushion structures were made to investigate the reinforced cushion effect of the soft soil foundation embankment. The soft soil foundation settlement, tensile force in the cushion course and vertical compressive forces at the bottom of embankment were measured. Test results show as follows：The reinforced cushion can effectively reduce and homogenize soft soil foundation settlement induced by upper embankment loading and restrict horizontal deformation of the foundation surface, and the rigid cushion has better effect than the flexible cushion;flexible cushions can homogenize vertical compressive forces at the bottom of embankment to a certain degree, distribution of the vertical compressive forces at the bottom of embankment is related to the cushion structure and the magnitude of the embankment load;along with increasing of the embankment load, the distribution curve of the horizontal tensile forces in the rigid cushion is shaped like ＂M＂, and the distribution curve of the reinforcing tensile forces in the flexible cushion changes from the ＂M＂ shape to the pot-shape gradually; in the case of ignoring the friction of embankment, the tensile forces in the rigid and flexible cushions under the shoulders of the subgrade formation can be calculated by the Rankine active earth pressure formula and passive earth pressure formula separately.