This paper presents a numerical study on the static and dynamic behavior of Combined Piled Raft Foundations (CPRF) with connecting and non-connecting configurations. Using finite element modeling, the influence of cushion layer thickness on stress distribution and seismic response is examined. The analysis focuses on key parameters such as bending moment and acceleration amplification under both static and dynamic loading conditions. Results indicate that CPRFs with thicker cushion layers exhibit more uniform stress distribution and improved seismic performance. In particular, non-connecting configurations benefit significantly from increased cushion thickness, which helps mitigate seismic wave transmission and reduce acceleration amplification in the superstructure. The findings contribute to the broader understanding of soil–structure interaction and provide practical guidance for optimizing foundation performance in urban infrastructure.