移动荷载作用下既有高速铁路路基拓宽计算分析

通过有限元软件PLAXIS对土工合成材料加筋既有高速铁路路基的加筋效果和动态响应特性进行分析，以具体拓宽道路为例，对比有限元仿真模型计算结果与典型试验结果，验证了有限元模型的准确性，并对比了三维与二维模型的差异，研究了既有高速铁路加宽路基在移动荷载作用下的动态响应特性。结果表明：在列车动荷载作用下，变形不仅发生于荷载正下方路基，路基两侧的坡面上也伴随变形发生，且靠近加宽路基一侧的坡面变形更明显，相对整体而言，加宽路基处更容易发生过大的变形而导致失稳破坏。路基表面应力变化有一定滞后性，动应力衰减系数与列车速度呈正相关。相较于列车静载，列车动荷载产生的路基表面峰值应力更大。路基沉降与路基高度总体上呈现出正相关趋势，随着高度的降低，沉降减少。路基坡面横向变形随列车的运动响应较快，最大横向变形发生在路基上部。利用土工格栅对既有高速铁路加宽路基加筋，可显著改善路基变形特性，结合经济效益分析，在中上部进行加筋效果较优。

Calculation and Analysis of Existing High-speed Railway Subgrade Widening under Moving Load

Analysis of the reinforcement effect and dynamic response characteristics of the geosynthetic reinforced existing high-speed railway roadbed by means of the finite element software PLAXIS, taking the specific widening of the road as an example, comparing the calculation results of the finite element simulation model with the typical test results, verifying the accuracy of the finite element model, and comparing the differences between the three-dimensional and two-dimensional models, and studying the dynamic response characteristics of the widened roadbed of the existing high-speed railway under the action of moving loads. The results show that there is a certain hysteresis in the surface stress change of the roadbed, and the dynamic stress attenuation coefficient is positively correlated with the train speed. Compared with the static load, the peak stress of the subgrade surface caused by the dynamic load is larger. Settlement and the height of the subgrade generally show a positive correlation trend. As the height decreases, the settlement decreases. The lateral deformation of the subgrade slope responds quickly to the movement of the train, and the maximum lateral deformation occurs on the upper part of the subgrade. The geogrid is used to reinforce the widened subgrade of an existing high-speed railway. The results show that the deformation characteristics of the subgrade can be significantly improved. Combined with the analysis of economic benefits, the effect of three-layer reinforcement in the middle and upper part is better.