According to the technical characteristics of short fixed wheelbase of a high-speed carriage, a subgrade-track integrated space mechanical response analysis model is proposed for trains under the action ofbiaxial load...According to the technical characteristics of short fixed wheelbase of a high-speed carriage, a subgrade-track integrated space mechanical response analysis model is proposed for trains under the action ofbiaxial load after the comparison of the stress distribution characteristics of the ballast track subgrade bed structures for high-speed railway under the action of uniaxial load and biaxial load. The loading threshold value （high-cycle long-term dynamic strength） under the circum- stance where the cumulative deformation of subgrade structure gradually develops and finally reaches the convergent state, and its relationship with the foundation coefficient K30 were deduced, based on the characteristics of cumulative defor- mation evolution obtained from the unit structure filling model test under the action of cyclic loading. In view of structure stability and frost resistance requirements of the railway subgrade in cold regions, technical conditions to maintain good service performance of subgrade structure of high-speed railway ballasted track are discussed and analyzed. Study results show that the additive effect manifests itself obviously for railway train bogies under the action of biaxial load than uni- axial load, which has a significant dynamic effect on the subgrade bed bottom and a slight effect on the surface layer. Thus, the adoption of a biaxial load model in the design of a high-speed railway subgrade accurately reflects the vehicle load. Pursuant to the structure design principle, the design method of the subgrade structure of high-speed railway ballasted track is proposed to meet the technical requirements such as structural strength, bearing stiffness and high-cyclic and long-term stability. Technical indicators are obtained for the variation of thickness of the surface layer of reinforced sub- grade bed in the double-layer subgrade mode along with the change of K30 at the subgrade bed bottom. The double-layer structure mode of ＂closure on the upper layer and drainage on the lower layer＂ was proposed in order to meet the water- proofing and drainage requirements of the upper layer of the subgrade bed in cold regions. A dense-framework graded gravel filler with weak water permeability at a coefficient of 10 4 cm/s is used on the upper layer and the void-framework graded gravel filler at the water permeability coefficient of 10 2 cm/s is adopted on the lower layer.展开更多
基于设计的轧辊孔型,使用三维有限元分析软件Simufact,对28Ni Cr Mo V8.5钢管典型规格准16 mm×1.5mm皮尔格冷轧过程进行了数值模拟。研究了不同摩擦系数及孔型开口系数对冷轧管横向壁厚分布及精度的影响规律。结果表明:钢管的横向...基于设计的轧辊孔型,使用三维有限元分析软件Simufact,对28Ni Cr Mo V8.5钢管典型规格准16 mm×1.5mm皮尔格冷轧过程进行了数值模拟。研究了不同摩擦系数及孔型开口系数对冷轧管横向壁厚分布及精度的影响规律。结果表明:钢管的横向壁厚分布是不均匀的,在孔型开口及孔顶处出现最小值,在孔型侧壁角45°两侧出现最大值。随着摩擦系数和孔型开口系数增大,不均匀的横向壁厚变得更加严重。当轧辊与轧件的摩擦系数由0.080增大到0.095时,冷轧管的横向壁厚精度由5.51%变到6.98%;当孔型开口系数由0.051增大到0.061时,横向壁厚精度由5.51%变到8.11%。展开更多
基金financially supported by the State Key Development Program for Basic Research of China(973 Program,Grant No.2013CB036204)
文摘According to the technical characteristics of short fixed wheelbase of a high-speed carriage, a subgrade-track integrated space mechanical response analysis model is proposed for trains under the action ofbiaxial load after the comparison of the stress distribution characteristics of the ballast track subgrade bed structures for high-speed railway under the action of uniaxial load and biaxial load. The loading threshold value （high-cycle long-term dynamic strength） under the circum- stance where the cumulative deformation of subgrade structure gradually develops and finally reaches the convergent state, and its relationship with the foundation coefficient K30 were deduced, based on the characteristics of cumulative defor- mation evolution obtained from the unit structure filling model test under the action of cyclic loading. In view of structure stability and frost resistance requirements of the railway subgrade in cold regions, technical conditions to maintain good service performance of subgrade structure of high-speed railway ballasted track are discussed and analyzed. Study results show that the additive effect manifests itself obviously for railway train bogies under the action of biaxial load than uni- axial load, which has a significant dynamic effect on the subgrade bed bottom and a slight effect on the surface layer. Thus, the adoption of a biaxial load model in the design of a high-speed railway subgrade accurately reflects the vehicle load. Pursuant to the structure design principle, the design method of the subgrade structure of high-speed railway ballasted track is proposed to meet the technical requirements such as structural strength, bearing stiffness and high-cyclic and long-term stability. Technical indicators are obtained for the variation of thickness of the surface layer of reinforced sub- grade bed in the double-layer subgrade mode along with the change of K30 at the subgrade bed bottom. The double-layer structure mode of ＂closure on the upper layer and drainage on the lower layer＂ was proposed in order to meet the water- proofing and drainage requirements of the upper layer of the subgrade bed in cold regions. A dense-framework graded gravel filler with weak water permeability at a coefficient of 10 4 cm/s is used on the upper layer and the void-framework graded gravel filler at the water permeability coefficient of 10 2 cm/s is adopted on the lower layer.
文摘基于设计的轧辊孔型,使用三维有限元分析软件Simufact,对28Ni Cr Mo V8.5钢管典型规格准16 mm×1.5mm皮尔格冷轧过程进行了数值模拟。研究了不同摩擦系数及孔型开口系数对冷轧管横向壁厚分布及精度的影响规律。结果表明:钢管的横向壁厚分布是不均匀的,在孔型开口及孔顶处出现最小值,在孔型侧壁角45°两侧出现最大值。随着摩擦系数和孔型开口系数增大,不均匀的横向壁厚变得更加严重。当轧辊与轧件的摩擦系数由0.080增大到0.095时,冷轧管的横向壁厚精度由5.51%变到6.98%;当孔型开口系数由0.051增大到0.061时,横向壁厚精度由5.51%变到8.11%。
