Long Term Impact Of New Established High-speed Railway At Soft Soil Area On Adjacent Existing Railway

Along with the increasing density of railway network, new established high-speed railway is adjacent to existing railway inevitably. Furthermore, vibration generated by passing trains in soft soil area, is a serious problem. It’s necessary to study how vibration generated by high-speed train, built in soft soil area, impacts the existing railway’s clay foundation. This article takes Shanghai-Nanjing intercity high-speed railway and adjacent Beijing-Shanghai railway as an example, theory and field measurement data are combined to establish system dynamic simulation model. After researching how vibration generated by high-speed train and long term vibrating load impacts the existing railway, several conclusions are made as follows:(l)Using system dynamic analysis theory, two models are established, they’re vehicle-track coupling dynamic model and new line-subgrade soil-existing line three-dimensional finite element model. Compared with field measurement data, the model is justified and the calculating result is verified, which provides the calculating model to study the impact vibration generated by high-speed train acts on existing line’s clay foundation.(2)Dynamic response of existing line’s clay foundation is analyzed under different conditions (trains travel only on existing line or both existing and high-speed lines), different midways, and different subgrade soil. It illustrates that both the maximum horizontal and longitudinal distribution of dynamic deviator stress are similar to the shape of saddle, they occur at the sleeper or the wheel set position; along with depth, the stress decays rapidly in0m～3m, decays slowly in3m～11m, and when it goes deeper than17m, the stress is already below0.1kPa. Dynamic deformation distributes similar to dynamic deviator stress, only more evenly.(3)How high-speed train influences existing line’s clay foundation, both dynamic deviator stress and dynamic deformation, is calculated. It contributes only1.47%to dynamic deviator stress, and1.52%to dynamic deformation, which demonstrates that it influences a little to existing line’s clay foundation. On the other hand, changing midway and subgrade soil do enhance the influence high-speed train acts on dynamic deviator stress and dynamic deformation of existing line’s clay foundation in a certain extent.(4)Calculate the cumulative plastic deformation of existing line’s clay foundation with different conditions, midways and different subgrade soil, analyze how long term high-speed train vibrating load influences cumulative deformation of existing line’s clay foundation:the result tells that in realistic, long term high-speed train vibrating load influences cumulative plastic deformation only a little, merely0.864%; cumulative plastic deformation of ground’s topmost caused by high speed train vibrating load changes with different midways and subgrade soil, but it only occupy a little compared to the cumulative deformation caused by vibration generated by trains travel at the existing line itself.