静载作用下土工格栅加筋拓宽路堤土中应力特征试验研究

Experimental study of soil stress characteristics of geogrid-reinforced widened embankment under static loadings

为探究荷载作用下软土地基直接拼接拓宽路堤受力和变形特征,利用自行设计制造的模型试验系统,通过改变软土地基差异沉降、土工格栅加铺层数对软土地基高速公路直接拼接路堤进行一系列模型试验,研究各种工况下旧路与新拓宽路堤土中应力变化。试验结果表明,拓宽路堤在荷载作用下新旧路各断面土中竖向应力随着荷载的增大而增大,受路堤填土边坡与下伏地基侧向约束条件的影响,荷载作用下土中竖向应力在填土路堤与地基内沿深度方向呈现先减小、后增大、再减小的分布特征;软土地基拓宽路堤差异沉降对新旧路结合部位土中竖向应力影响较大,土中竖向应力随着差异沉降增大而增大;旧路范围内土中竖向应力受差异沉降的影响不大;在拓宽路堤填土的顶部和底部各布设一层土工格栅加筋层时可明显减小路堤土中竖向应力和路堤沉降:相同荷载作用下对比无加筋路堤,铺设2层土工格栅加筋路堤的顶面沉降最大可以减少62%,土工格栅加筋对软土地基拓宽路堤沉降有较好的控制作用。

In order to explore the stress and deformation characteristics of widened embankment which directly built on soft ground under static loading, a self-designed and self-made model test system is adopted. A series of model tests are carried out on this test system. By changing the value of the differential settlement and the layers of geogrid, variation characteristics of the soil stress in the old and new widened embankments are studied. The test results show that the vertical stress in the soil of both new and old sections of widened embankment increases with the load increase. The vertical stress decreases at first, then increases and finally decreases along the depth direction under the influence of the filling slope of embankment and the underlying foundation with lateral restraint. The differential settlement of the widened embankment built on soft ground has significant influence on the vertical stress at the junction between the old and new roads, the vertical stress in this area increases with the differential settlement, while the vertical stress in the old road is rarely influenced. Vertical stress and settlement of the embankment can be obviously reduced when geogrid reinforcement layers are laid at both the top and bottom of the widened embankment. Compared with non-reinforced embankment, the settlement on the top surface of embankment reinforced with 2 layers of geogrid can be reduced by 62% at most, which shows the geogrid reinforcement has a good control on the settlement of embankment built on soft ground.