膨胀土路堑基床新型防水层振动荷载下服役性能试验研究

Tests for working property of water-proof layer of cutting subgrade in expansive soil under vibrating load

膨胀土路堑基床病害是铁路工程中亟需解决的关键技术问题。针对新建云桂线膨胀土地段高速铁路工程实际,开展膨胀土路堑基床模型室内激振试验,研究新型防水结构层在干燥、降雨、地下水位上升三种极端服役条件下的动力性能及防水效果,并结合现场实测数据进行了分析。分析结果表明:服役环境对新型基床结构的动力特性影响显著,降雨和地下水位上升均引起基床动应力、速度及加速度不同程度的增加;新型防水结构层可加快基床内部动应力的衰减,动应力沿横向距离近似呈"Z"形分布,在轨道正下方出现峰值,距线路中线5.0 m以外受振动影响较小;新型防水结构层能满足的防水、隔水、抗振、减振的要求,对提高铁路线路的平顺性和稳定性具有积极意义。研究成果可为新建云桂膨胀土高速铁路工程建设及同类工程实践提供参考。

The defect of cutting subgrade in expansive soil is a key technical problem of railway engineering to be solved urgently. According to the actual conditions of the new Yun-Gui line of a high-speed railway project in expansive soil areas,the model tests for cutting subgrade in expansive soil were conducted to study the dynamic performance and waterproof effect of a new water-proof structure layer under three types extreme service conditions（ dry,raining,and underground water rising）,and they were analyzed combining with the field measured data. The analysis results showed that the influences of the service environment on the dynamic characteristics of the new subgrade structure are significant;the dynamic stress,velocity and acceleration of the subgrade increase at different levels due to raining and underground water rising; the waterproof layer can accelerate the attenuation of the dynamic stress in the subgrade,the dynamic stress along the transverse distance reveals ＂Z＂shape distribution,and its peak value appears at below the track,and it is smaller at place with a distance more than 5 metres from the railway central line under vibration; the new type waterproof structure layer can meet requirements of waterproof,impenetrability,anti-vibration and impact-absorbing,and using it can improve the ride performance and stability of railway track. The results provided a reference for the construction of the newly built Yun-Gui high-speed railway in expansive soil and similar projects.