Characterizing a Tropical Soil Site using Seismic Dynamic Probing Light (SDPL)

Site investigation is an important stage of geotechnical engineering as it defines the stratigraphic profile and mechanical and hydraulic parameters of the layers of interest. In situ tests are interesting techniques as they allow estimating soil parameters at the project site, with lower costs and quick execution on large volumes of soil. The Dynamic Penetrometer Light (DPL) is an interesting alternative for site investigation, as it can be used in locations where conventional sounding equipment may have limited access and is sensitive to the small variations that occur along the profile due to its low penetration energy. Shear wave velocity (Vs), is an important parameter allowing the characterization of a soil in the elastic range. In this paper, the hybrid tests called the seismic DPL (SDPL), which combine stratigraphic logging, estimation of geotechnical parameters and Vs determination is presented. The rational interpretation of the DPL test results in terms of the tip (qp) and sleeve (τl) resistances were equivalent to the CPT cone resistance (qc) and sleeve friction (fs) values, once considered the scale effect for the sleeve resistance. Shear wave velocity (Vs) was determined by the downhole seismic technique and the results are like the cross-hole and SDMT carried out on the site. The SDPL test can be used in the preliminary site characterization of tropical soils combining the rational interpretation of DPL data and the downhole seismic data. The presence of microstructure (cementation and aging) in tropical soils and the collapsibility of the study site were assessed using the G0/qp ratio based on the qp values and the maximum shear modulus (G0).