Abstract: The study investigates the acoustic properties of siltclay mixed soils with different clay-particle contents (CC) from a geomechanical perspective through laboratory testing, focusing on how clay content and saturation influence P-wave velocity in the Yellow River Delta. The results show that increasing clay-particle content hinders P-wave propagation in the soil. Under fully saturated conditions, higher excitation frequencies correspond to higher P-wave velocities. When specimens are in a near-saturated state, the rate of change in P-wave velocity differs when clay contents reach 20% and 40%, and higher clay content produces a stronger influence on P-wave velocity. This phenomenon is related to porosity, which increases nonlinearly with clay content; at 20% and 40% clay content, the rate of porosity change also increases. Variations in porosity are associated with the distribution of clay particles within the pore space. The Thomas-Stieber model is used to analyze the spatial distribution of clay, providing a microscopic interpretation of how clay exists within pores at different clay-particle contents.

Key words: Yellow River Delta, P-Wave Velocity, Viscous Grain Content Threshold, Saturation, ThomasStieber Model