Study on the mechanical behavior of a foundation pit retaining structure adjacent to the pile foundation of a subway station

The numerous effects of adjacent structures should be considered in the design and construction of subway stations. The subway station expansion project confined to a small space in Shenzhen City was taken as engineering background to study the earth pressure distribution in a limited space. Both theoretical analysis and laboratory model testing methods were used to study the mechanical behavior of the subway station retaining structure adjacent to a pile foundation. The main conclusions are as follows: (1) When the soil around the foundation pit is non-cohesive, the soil pressure is smaller than that calculated by classical soil pressure theory, and the difference between the two increases with an increase in the angle of internal friction. If the lateral inclination continues to increase, then the pressure will approach the value determined by classical theory. (2) The soil pressure distribution and variation rule are greatly influenced by factors such as the length-diameter ratio, excavation depth, internal friction angle and friction between the soil and retaining structure. The dip angle of the sliding surface of the finite soil increases with decreasing friction angle and is inversely correlated with the aspect ratio. The active soil pressure is inversely proportional to the internal friction angle of the soil and positively correlated with height. When the internal friction angle is constant and the length–diameter ratio is equal to the critical length–diameter ratio, the active earth pressure coefficient is equal to the Coulomb active earth pressure coefficient and reaches its maximum value. (3) The deformation of the foundation pit retaining structure has an important influence on the distribution of soil pressure around it. These results offer a reference for the engineering design and construction of supporting structures for deep foundation pits adjacent to existing adjacent structures.