Selection Design and Parameter Optimization of Composite Foundations in Collapsible Loess Areas

With the rapid development of railway construction in China, the role of passenger railway lines is becoming increasingly prominent. The construction of passenger railway lines is of great importance to the development of high-speed railways in Western China. Most regions in Western China are collapsible loess areas, and the collapsibility characteristics of loess are extremely unfavorable to foundation treatments. Therefore, the engineering properties of collapsible loess should be fully considered in foundation treatments, and corresponding treatment measures should be taken. In this paper, the displacement and stress characteristics of collapsible loess foundations are studied based on a test section of a subgrade treatment project in combination with engineering geology; this study aims to analyze several kinds of collapsible loess foundation treatment methods, such as single piles and group piles. The mechanism of the method is to make full use of the bearing capacity of the natural foundation, so that the soil between the piles is jointly to bear with pile, thereby the bearing capacity of the foundation is improved and the settlement of the foundation is effectively controlled. After the form of the composite foundation is selected, the foundation bearing capacity is improved by a parameter optimization design, and the foundation settlement is reduced, which eliminates the collapsibility of the loess. With field bearing tests, the rationality of the composite foundation design is verified.