防排水结构层对铁路基床动力响应的影响研究

Effect of Waterproofing and Drainage Structure Layer on Dynamic Response of Railway Subgrade Bed

针对云桂铁路膨胀土路堑新型基床结构采用的半刚性复合防水材料的防排水结构层,借助现场试验方法和数值模拟方法,研究列车振动荷载作用下防排水结构层对路堑基床动力响应的影响。结果表明:基床动土压力沿深度方向呈指数衰减,并且铺设防排水结构层可加快基床内动应力的衰减;基床动位移沿深度方向近似呈幂函数衰减,为满足高铁路基变形的要求,建议防排水结构层铺设厚度不小于15cm;振动加速度随深度加深而减小,其衰减主要发生在路基表面下的3.0m范围内;增加防排水结构层厚度可减弱防排水结构层下部的动应力、路基表面的动位移及基床下部的振动加速度;铺设防排水结构层可起到防水、排水、消能、抗变形等作用,对控制膨胀土基床病害有积极意义。

The waterproofing and drainage structure layer with semi-rigid compound waterproof material was adopted for the new subgrade bed of expansive soil cutting of Yun-Gui railway.The effect of waterproofing and drainage structure layer under train vibration load on the dynamic response of subgrade bed was studied by means of field tests and numerical simulation.The results show that the dynamic earth pressure of subgrade bed attenuates exponentially along depth direction,and the laying of waterproofing and drainage structure layer can accelerate the attenuation of the dynamic stress in subgrade bed.The dynamic displacement of subgrade bed attenuates approximately by power function along depth direction.It is recommended that the laying thickness of waterproofing and drainage layer should be no less than 15 cm so as to meet the requirement for the deformation of high speed railway subgrade.The vibration acceleration decreases with the increase of depth,and its attenuation mainly occurs within 3.0mdepth below subgrade surface.To increase the thickness of waterproofing and drainage structure layer can reduce the dynamic stress under the structure layer,the dynamic displacement of subgrade surface and the vibration acceleration under subgrade bed.The waterproofing and drainage structure layer functions waterproof,drainage,energy-dissipation and anti-deformation,and it has positive significance to control the subgrade bed diseases of expansive soil.