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膨胀土地区路堑基床病害是高速铁路建设中倍受关注的问题。结合云桂高速铁路工程实际,以典型膨胀土新型路堑基床为基础,借助有限差分软件FLAC~(3D),建立了三维路堑基床动力分析模型,探讨了列车荷载作用下新型全封闭路堑基床动力特性,并结合现场试验进行了分析。分析结果表明:数值模拟结果可较好地反映基床动响应变化规律,且与现场实测变化趋势相同;基床竖向动应力随深度呈指数型衰减,基床竖向动位移随深度呈幂函数型衰减;路基面动位移值为0.95 mm,满足高速铁路规范要求;基床动响应特征受服役环境影响显著,浸水条件下会引起基床表层动应力及振动速度增大;铺设防排水结构层可改善基床内的动应力分布,并减小路基面的动位移及增强基床抗振性能。研究成果可为膨胀土地区高速铁路工程实践及理论研究提供参考。
In the expansive soil area, the cutting bed disease is a concern in high-speed railway construction. Combining with the actual project of Yunnan-Guangxi high-speed railway, the dynamic analysis model of three-dimensional cutting bed was established based on the new expansive soil bed of bedrock with finite difference software FLAC (3D), and the effects of the new fully enclosed cutting foundation Bed dynamic characteristics, combined with field tests were analyzed. The results show that the numerical simulation results can well reflect the change law of dynamic response of bedrock, and have the same trend with the field test. The vertical dynamic stress of bedrock decreases exponentially with depth, and the vertical dynamic displacement of bedrock increases with the depth Function attenuation; Subgrade dynamic displacement of 0.95 mm, to meet the requirements of high-speed railway specifications; bed dynamic response characteristics of the service environment significantly affected under flooding conditions will cause the bed surface dynamic stress and vibration speed increases; laying drainage structure The bed can improve the dynamic stress distribution in the bed and reduce the dynamic displacement of the roadbed surface and enhance the anti-vibration performance of the bed. The research results can provide references for high speed railway engineering practice and theoretical research in expansive soil area.