Numerical Modeling of soft soil improvement by stone columns under high-speed train passage

Rail transport has unique advantages over other modes of transport, such as less environmental vulnerability, less pollution and more safety than other modes of transport. Due to the lack of lands with adequate load-bearing capacity, parts of the railway route are built on soft soils, which the possibility of creating instability and subsidence of railway lines in this type of soil is one of the main concerns of engineers. High-speed trains are now used in developed countries to reduce travel time, which can significantly increase the dynamic responses of components on railroad tracks, especially when the train is traveling at a critical speed. One of the ground improvement methods that has been widely used recently for the improvement of soft sediments and loose fine-grained soils is the rock column method. High-speed trains are two important factors in the operation and use of the railway complex. In this research, the performance of stone columns in the bed of high-speed trains to reduce soil subsidence and prevent the occurrence of asymmetric subsidence in different conditions and under the influence of various factors has been investigated. The results showed that with increasing column length Stone and its diameter decreases, asymmetric settling and subsidence due to high-speed train passage is reduced. Also, increasing the hardness of the geogrid reduces the subsidence.