基于XCT扫描技术的铁路路基翻浆冒泥机理研究

Study on the mud pumping mechanisms of railway subgrade based on X-ray computed tomography technology

为研究铁路基床性翻浆冒泥的发生机理,本文结合XCT扫描试验技术试验观测了循环荷载下饱和基床翻浆冒泥通道形成全过程,以及发生翻浆冒泥时内部孔隙水的运移规律。研究表明,基床内翻浆冒泥通道的形成是铁路路基翻浆冒泥启动的关键。静荷载作用下,基床内不会出现翻浆冒泥通道,底部孔隙水随荷载次数增加而整体上升;当土体受到循环荷载时,基床孔隙水压迅速累积升高,在土体内部逐渐发育出输水通道,导致路基底层颗粒向上迁移而形成翻浆冒泥。基床性翻浆冒泥可分为3个阶段,孔压累积阶段、通道发展阶段与抽吸阶段。翻浆冒泥通道发展速度随着荷载幅值的增大而增加。最后采用嵌入强间断数值方法来模拟土体试验时翻浆冒泥通道的发展,分析了不同土体黏聚力对地基输水通道形成的影响规律,发现随着土体黏聚力的升高,土体内输水通道发展速度降低。本研究可为软土地基道路翻浆冒泥的预防与治理提供参考。

To investigate the mechanisms of the mud pumping of subgrade bed,this paper observes the whole formation process of saturated subgrade mud-flushing channel under cyclic loading and the internal pore water movement law during mud-flushing based on X-ray computed tomography technology.The research shows that the formation of mud pumping channel in subgrade bed is the key to the start-up of mud pumping in railway subgrade.Under static loading,there is no mud pumping channel in the subgrade bed,and the bottom pore water increases with the increase of load times.When the soil is subjected to cyclic loading,the pore water pressure of the foundation bed increases rapidly,and the water conveyance channel is gradually developed inside the soil,which leads to the upward migration of the particles in the bottom layer of the road and the occurrence of mud pumping.The development of mud pumping in base-bed slurry can be divided into three stages:pore pressure accumulation stage,channel development stage and suction stage.The development speed of the mud pumping channel increases with the increase of the load amplitude.Finally,the embedded strong discontinuity numerical method is used to simulate the development of mud pumping channel during soil tests,and the influence of soil cohesion on the formation of foundation water conveyance channel is analyzed.It is found that the development speed of water conveyance channel in soil decreases with the increase of soil cohesion.This study can provide a reference for the prevention and treatment of mud pumping in soft soil foundation road.