Analysis of Vertical Dynamic Coupled Response for Cement‐Modified Soil Composite Pipe Piles in Fractional Order Viscoelastic Saturated Soils

ABSTRACT This research examines cement‐treated soil composite pile pipes' axial load response via elastic dynamics principles. A novel theoretical model for describing the vibration response of pile‐soil systems is developed, integrating Biot's poroelastic medium theory and the non‐integer order model. By concurrently solving the soil control equation and the axial vibration model of the pile system, an exact analytical expression for the dynamic impedance at the pile tip was derived. Comprehensive parametric studies have elucidated the significant impact of the physical properties of both piles and surrounding soil on the seismic performance of pile foundations. Key findings indicate that (1) fractional‐order model parameters significantly influence vibration attenuation characteristics; (2) optimizing structural parameters, such as radial dimensions (inner and outer radii), pile length, and elastic modulus ratios between cement‐soil composites and concrete components, can substantially enhance vibration resistance; and (3) to effectively reduce vibrations in saturated soil foundations, the ideal setup involves ensuring the concrete pipe's radius makes up roughly 40%–60% of the overall radius. Additionally, the pile length should be about 20–30 times the total radius, while the cement‐soil modulus needs to stay within a narrow range of 2%–5% of the concrete pipe's modulus. These parameters strike the right balance for optimal performance. This analytical framework provides theoretical guidance for designing vibration‐resistant composite pile foundations in saturated soil conditions.