Evaluation of Ground Improvement Techniques using Surface Wave Methods

Ground improvement techniques are commonly used in geotechnical engineering to enhance the mechanical behaviour of soft soils. Surface wave methods, such as SASW and MASW, offer an effective, non-invasive means to assess these improvements through shear wave velocity (Vs) profiles. This study presents the application of both techniques to evaluate two treated sections of a high-speed railway line under construction in southeastern Spain. One section was reinforced using gravel columns, while the other was improved through staged embankment construction over prefabricated vertical drains. Geophysical surveys were carried out in two campaigns: shortly after treatment in 2023 and after full embankment construction in 2024. Results show a significant increase in Vs values in the treated layers and underlying soils, which confirms the consolidation and stiffening effects induced by the treatments. The results also highlight the complementary strengths of SASW and MASW techniques. The study assesses the suitability of surface wave methods for monitoring ground improvement treatments