Performance of High Speed Railway Subgrade Strengthened by Long-Short Piles: Part II—Numerical Modelling

The Yinxi Railway is located in the western region of China. As a high speed railway line connecting Yinchuan-Xi’an, which is of great significance for the construction of transportation facilities in western China. Because the Yinxi Railway passes through loess areas, cement fly-ash gravel (CFG) long piles and cement-soil compacted (CSC) short piles are used for the subgrade treatment method. In Part I of this paper, experimental results relating to the effect of the composite foundation were presented. In Part II, finite element analysis are undertaken of the influence of the change of physical parameters of the composite subgrade caused by different cement content on the subgrade performance. The results show that the performance of the composite subgrade can be fully achieved under the condition of achieving the best cost performance by selecting the appropriate ratio of cement-modified soil, which provides a certain reference for the optimization of design parameters of similar composite subgrade projects in the future.