基于有限元的地基-路堤-路面协同变形机理分析

Analysis on Mechanism of Foundation-embankment-pavement Cooperative Deformation Based on FEM

我国软土地基分布广泛,在软土地基上修建工程建筑物时,不同位置上产生的变形量大小不同,修建在软土地基上的高等级公路常因软基不均匀沉降导致路面服务性能降低甚至发生结构性破坏。为了避免这些破坏的产生,需研究软土地基病害和其不均匀变形在道路面层结构中的传递机理,本研究运用数值模拟方法建立了地基-路堤-路面协同作用的力学模型,在建立的ABAQUS数值模型中,由上至下各层分别为面层、路堤、砂垫层、淤泥质黏土4层。分析了不同路堤填料路堤在不同车辆荷载、填筑高度及填料模量下的变形规律:土石混合料路堤的沉降最大沉降量和车辆轴载及路堤填筑高度均成正比,沉降量随着填筑材料模量的增加不断减小,且减慢速率不断减小,并提出了地基-路堤-路面三者组合的变形协同机理。发现沉降量在道路结构中向上传递会叠加路堤压缩变形以及道路结构层的厚度变化,且随高度逐渐减小的协同变形。地基-路堤-路面模型的整体变形规律为:软土地基施工结束后,在路堤和路面填筑过程中发生固结,水分排出引起沉降,沉降曲线为沿道路中线对称的抛物线形状。分层填筑路堤时,填料进行固结作用产生竖向变形,但与软土地基产生的竖向变形量相比可忽略不计。路堤与面层为适应地基沉降发生协调变形:路面结构在荷载和自重作用下,产生层间协调变形以填充路堤固结沉降产生的空间,但是由于结构层变厚软基沉降量向上传递时表现为不断减小。

Chinese soft soil foundations are widely distributed.When constructing engineering buildings on soft soil foundations,the deformations generated at different locations are various.High-grade roads on soft soil foundations often result in reduced pavement service performance or even structural damages due to uneven settlement of soft foundations.In order to avoid the occurrence of these damages,it is necessary to study the transfer mechanism of soft soil-based diseases and their uneven deformation in road surface layer structure.The mechanical model of foundation-embankment-pavement synergy is established by numerical simulation method,and there are 4 layers(surface course,embankment,sand cushion and silty clay)from top to bottom layers in the established ABAQUS numerical model.The deformation rules of the embankments filled with different fillers under different vehicle loads,filling heights and moduli are analyzed:the maximum settlement of earth-rock mixed embankment is proportional to the axle load of the vehicle and the embankment filling height,the settlement decreases with the increase of the modulus of the filler,and the slowing rate also decreases.The deformation synergetic mechanism of foundation-embankment-pavement combination is proposed.It is found that the upward transfer of the settlement amount in the road structure will superpose the compression deformation of the embankment and the thickness variation of the road structure layers,and the synergistic deformation gradually decreased with the height change.The overall deformation rule of the foundation-embank-pavement model is:after the construction of the soft soil foundation,consolidation occurs during the embankment and pavement filling process,the water discharge causes settlement,and the settlement curve is a parabolic symmetric shape along the middle line of the road.When the embankment is filled in layers,the consolidation of the filler produces vertical deformation,but it is negligible compared to the amount of vertical deformation produced by the soft soil foundation.The coordinated deformation of embankment and the surface layer occurs to adapt to the settlement of the foundation:under the action of load and self-weight,the pavement structure produces coordinated deformation between the layers to fill the space created by the consolidation settlement of the embankment.However,as the structural layer becomes thicker,the settlement of the soft foundation appears to decrease continuously.