客运专线无砟轨道桩网结构模型试验研究

无砟轨道线路状态的调整只能通过扣件系统进行,其对轨下的基础沉降、差异沉降及弯折变形提出严格要求。为了研究在经过桩网结构地基加固后的土质路基上修建的无砟轨道是否满足要求,在室内进行了桩网结构大比例模型试验研究,测试在填筑和循环载荷试验情况下的路基沉降、基床动应力、桩顶与桩间土土压力,以及桩的应力应变分布等数据。研究表明:①桩网结构累积沉降值较小,能满足无砟轨道对工后沉降25.0 mm的要求;②桩网结构中的网具有荷载分担作用,桩起竖向增强作用,桩土应力比约为2.45;③桩的承载力由桩侧摩阻力与桩端支承力共同贡献,当地基中存在软土层时,桩侧有产生负摩阻力的趋势,中性点位于软土层下部交界面处。

Model Test of Column-net Structure for Dedicated Passenger Line Unballasted Track

The unballasted track railway line must meet the strict requirements of ground settlement,differential settlement and flex deformation,and adjustment of line can only go on through the rail fastenings system.The large-scale model test of the column-net structure was made in the laboratory to study the structure's effectiveness in controlling the soft ground settlement of the Sui-Yu Railway Line.The settlement of subgrade,dynamic stress of subgrade bed,soil pressures on the pile top and in the soil between piles,and stress distribution of piles are tested under the static fill and the dynamic cycle loading conditions.The research results indicate that: The post-construction settlement of the soil subgrade reinforced with the column-net structure is small enough to meet the design standard of settlement of 25.0mm;the net of the structure plays the role of load distribution,the pile is able to reinforce the structure in vertical direction,and the stress proportion of pile to soil is 2.45 approximately;the pile bearing capacity is composed of the lateral friction resistance and end bearing resistance,the existence of the soft soil interlayer in the foundation may result in negative friction,and the neutral point lies at the interface under the soft soil layer.