Soil Stiffness Gauge (SSG) and Dynamic Cone Penetrometer (DCP) tests for estimating engineering properties of weathered sandy soils in Korea

Laboratory tests are conducted using nondestructive and penetration methods for in-situ estimation of the engineering properties of weathered sandy soils in Korea. Soil Stiffness Gauge (SSG), Dynamic Cone Penetrometer (DCP), Plate Load Test (PLT), and California Bearing Ratio (CBR) are performed with three uncemented soil groups: poorly graded sand (SP), silty sand (SM), and well-graded sand with silt (SW-SM) that were compacted in a large container. The SSG and DCP results show acceptable repeatability. Dynamic Penetration Index (DPI) and the modulus of elasticity obtained from the SSG test (E_SSG) are significantly affected by the water content of SM and SW-SM soils, whereas the SP sample showed no clear effect of water content in either the DPI or E_SSG test. Compared with previous reports in the literature, the relationship obtained between CBR and DPI shows a similar trend although at a given DPI it produces significantly larger CBR values. For elastic moduli E_SSG is linearly proportional to E_PLT and is 1.7 times larger than E_PLT. For all three soils considered, the void ratio (e) is linearly proportional to the DPI divided by the median particle size (DPI/D₅₀) while the angle of internal friction is inversely proportional to DPI/D₅₀. The dry density of compacted soil appears to increase nonlinearly with increase in E_SSG.D₅₀/e. It is, therefore, concluded that E_SSG, DPI_, and D₅₀ can provide complementary information for the estimation of void ratio and dry density.