The contemporary two-parameter-based site classification system of Korea, which is depth to bedrock and averaged shear wave velocity of soil deposits overlying the bedrock, has been reported to be ineffective in representing the unique amplification characteristics of shallow bedrock profiles. A new site classification scheme conditioned on site natural period and corresponding intensity-dependent seismic coefficients for Korean site conditions is proposed based on extensive one-dimensional non-linear site response analysis outputs. It is highlighted that the proposed site classification system and site coefficients coupled with a new elastic response spectrum considerably reduce the residuals with the computed site response analysis outputs.

Earthworms have been commonly used for solid waste management by employing the process of vermicomposting. In this study, we used two different types of earthworm for vermicomposting and analyzed their efficacy for plant production in comparison to chemical fertilizer. The worms used for vermicomposting included Eisenia fetida (EF) and Lumbricus rubellus (LR), and we studied compost efficiency for the harvesting of spinach and turnips. The parameters we used to evaluate the performance of the produced compost on crops were variations in sprouting time, harvesting time, plant height, and plant yield. For the production of compost, the waste was collected and degraded in an environment where various parameters, including pH, moisture content, temperature, carbon, and nitrogen, were measured regularly throughout the experiment. The compost obtained from these three setups was used as a fertilizer to grow spinach and turnip. Compost efficiency was compared based on plant yield, plant height, sprouting, and harvesting time. In the case of turnip, the combination worm compost yielded 38% and 58% more than the compost obtained using EF and LR, respectively. For spinach, the EF–LR combined compost gave similar results, 17.4% and 37.9% more yield than the above two worms individually. The study’s results showed that the compost obtained by the combination of worms is more promising than the compost obtained from a single species and applied as fertilizer. Moreover, the comparative evaluation by statistical analysis confirmed that growing spinach by combined compost would be a better option compared to growing turnip, due to higher significant difference in outcome parameters.

A series of 3D finite element (FE) analyses were performed to estimate the peak penetration resistance of spudcan foundations in sand over clay soil profiles. Elasto-perfectly plastic models following Mohr–Coulomb and Tresca failure criteria were used for sand and clay layers, respectively. The coupled Eulerian–Lagrangian (CEL) approach was used to simulate the large deformation in soil that occurs during the spudcan penetration. The performance of the numerical model was validated against centrifuge test results. A parametric study with a broad range of strength parameters for sand and clay was performed. The numerical results were used to assess the influence of sand thickness (H_s), the diameter of spudcan (D), friction angle of sand, and undrained shear strength of clay (s_u). A wide range of s_u was utilized to predict the resistance both of the soft and stiff clays. The calculated peak resistances are compared with a published analytical model. It is demonstrated that the model highly overestimates the peak resistance for stiff clays, most likely because it was developed specifically for soft clays and, therefore, does not account for the influence of s_u. One of the parameters of the model is revised to account both for s_u. Comparisons highlight that the modified model is able to capture the simulated peak penetration resistance for both soft and stiff clays.