Silty fine sand presents significantly challenges in engineering construction due to difficulties in accurately determining its in-situ mechanical properties, the complexity of load transfer paths within foundations, its susceptibility to disturbance during excavation, and unclear patterns of bearing capacity reduction following disturbance. To address bearing capacity degradation and evaluate the feasibility of utilizing the fine sand layer as a natural foundation, a comparative analysis was conducted on static cone penetration test (CPT) data before and after excavation. The attenuation pattern of static penetration statistical values (P_S) with excavation depth was systematically investigated. A correction factor η for P_S values was proposed through fitting. A three-part comparative analysis was performed, involving corrected theoretical calculations, code-based conversions, and measured static load data. The results demonstrated that the corrected theoretical characteristic value of foundation bearing capacity (f_ak) closely aligned with measured data. The feasibility of adopting the fine sandy layer as a natural foundation stratum was confirmed. The proposed correction method was found to have significant advantages in accuracy, applicability, and practicality. A new approach was provided for predicting bearing capacity under complex geological conditions. Technical support was offered for foundation selection and design in similar regions. This methodology provides valuable references for similar projects, fosters regional standardization, and supports engineering goals of cost reduction and efficiency enhancement.