高铁膨胀土新型路堑基床动力特性与参数敏感性
Dynamic characteristics and parameter sensitivities of new cutting subgrade for high-speed railway in expansive soil area

进行了云桂高铁膨胀土新型路堑基床综合试验段现场激振试验,借助有限差分软件FLAC3D,建立了三维轨道-路基-地基动力学模型,分析了新型路堑基床动力响应与防排水结构层参数敏感性。分析结果表明:铺设新型防排水结构层可加速基床内动应力的衰减,降低路基表面动位移; 增加防排水结构层厚度和弹性模量可降低基床动位移,减弱防排水结构层下方基床动应力,但会提高防排水结构层顶面的动应力水平; 防排水结构层铺设位置下移时会增大路基表面动应力,但对路基表面动位移影响不大; 为满足《高速铁路设计规范》(TB 10621―2009)要求,建议防排水结构层铺设厚度不小于15 cm; 路基表面动应力、动位移与地基表面动应力敏感性因素依次是防排水结构层的铺设位置、弹性模量与铺设厚度; 考虑新型防排水结构层参数对基床动响应的影响,确定的最优方案为:铺设厚度为20 cm,弹性模量为1.0 GPa,铺设位置为基床表层底部。
The field vibration test of comprehensive experimental section for new cutting subgrade of Yun-Gui High-Speed Railway in expansive soil area was carried out, the 3D track-subgrade-base dynamics model was established by adopting the finite difference software FLAC3D, and the dynamic responses of new cutting subgrade and the factors sensitivity of water-proof structure layer were studied. Analysis result shows that the water-proof layer can accelerate the attenuation of dynamic stress in subgrade, and reduce the dynamic displacement of subgrade surface. Increasing the thickness and elastic modulus of water-proof layer can reduce the dynamic displacement and the dynamic stress of subgrade beneath the water-proof layer, but will increase the dynamic stress of water-proof layer surface. When the position of water-proof layer lowers, the dynamic stress of subgrade surface increases, but the dynamic displacement of subgrade surface hardly changes. It is recommended that the thickness of water-proof layer is not less than 15 cm for the requirements of Code for Design of High Speed Railway(TB 10621―2009). The sensitive factors to the dynamic stress and displacement of subgrade surface and the dynamic stress of base surface are the laying position, elastic modulus and thickness of water-proof layer in the influence order from big to small. Considering the factors' effects on the dynamic responses of subgrade, it is the optimal solution that the laying thickness of water-proof layer is 20 cm, the elastic modulus is 1.0 GPa, and the laying position is the bottom of subgrade surface. 7 tabs, 17 figs, 25 refs