The presence of underground voids in regions suitable for sustainable development can adversely affect the stability of the overlying infrastructures. In this paper, the collapse loads of strip rigid footings resting on sand with single and double continuous voids are determined for a frictional Mohr-Coulomb material following the non-associated flow rule. For use by practitioners, design charts are proposed to evaluate the well-known bearing capacity factor N_γ as a function of the dimensionless parameters related to the vertical and horizontal void distances from the footing, void shape, and spacing between the two voids, as well as the soil friction angle. The computational result compares quite favorably with the available theoretical and numerical solutions. The failure mechanism is broadly discussed based on the pattern of soil displacement around the footing and void.

Due to the impact of climate change, extreme rainfall events are becoming more frequent, resulting in shallow slope collapse and erosion that trigger debris flows. While traditional reinforcement methods like anchoring and nailing are effective, they can be costly and environmentally unfriendly. To address this issue, researchers have investigated using in situ soil reinforcement with vegetation, which is a more sustainable and economical option. In this study, a soil improvement agent was developed using leaf mold and herbal medicine to promote vegetation growth. Adding microcement and gypsum hemihydrate increased the shear strength of the soil, preventing surface erosion. A laboratory test confirmed that the combination of these ingredients effectively increased the soil’s resistance to erosion caused by rainfall. The soil improvement agent proposed in this study was applied to the case of the slope failure in the Gwangju area, South Korea, to confirm the slope stability for 10 days of rainfall. The results of numerical analysis confirmed that the reinforced slope cured by the pozzolanic reaction using the developed material improved the slope stability by 36% compared to the original soil slope during the rainy season.

Establishing a geotechnical rationale for an embankment overflow is challenging. The occurrence of embankment overflow is deemed unlikely since the initial highest water level of the embankment is assumed to be fixed as a designed flood water level or a seasonal flood-limited water level when calculating the rainfall amount in the hydrological stability analysis. However, the possibility of overtopping can be assessed by employing copula functions. This approach takes into account the return frequency of overflow and the fluctuation of probable water levels due to climate change rather than relying on the fixed highest water levels of an embankment. This study examined the effect of tensile cracks leading to the shallow failure of embankment slopes during drawdown and placed an emphasis on the vulnerability of embankment slopes due to extreme rainfall events. Throughout the comprehensive numerical simulations, it was found that the critical period for embankment slope collapse was immediately after drawdown for the upstream slope and during the initial stages of overflow for the downstream slope.

In this study, a mixture design test and case study were performed in a laboratory and on field, respectively, to evaluate the applicability of an eco-friendly porous media binder (CMD-SOIL) using desulfurized ash left behind in a power plant by waste. The deep cement-soil mixing method using desulfurization ash (CMD-SOIL) is effective as a new material that can be used to cope with the cement used in the conventional deep cement mixing method. In the laboratory-based mixture design tests, the uniaxial compression strength of CMD-SOIL was up to 1.14 times higher than that of slag cement when varying water content, mixing rate, and water/binder ratio. In addition, the CMD-SOIL shown strength of up to 1.22 times higher than that of oyster shell content and up to 1.36 times higher than that of a floating soil mixture. The case study showed that the uniaxial compression strength ratio (λ) of the improved porous media of the field to that of the laboratory (q_u(field)/q_u(lab)) was 0.77, similar to the general rate, in the design criterion. Therefore, the CMD-SOIL has sufficient strength and economical effect on the coastal construction, in which the shell layer is mixed with shellfish, or in the application of a construction technique for treating floating soils.

The voltage and electric current should be increased to improve power transfer capability; however, their increases cause heat to be generated in the cables. The thermal resistivity of backfill material around buried power cables depends on its water content. Although an underground power cable generally produces 60 degrees C heat, some power cables can cause thermal runaway in the dry condition. Thus, this triggers dielectric breakdown and creates factors that decrease power transmission efficiency. The objective of this study is to find the backfill material which maintains a low thermal resistivity in order to accommodate new cable systems that are designed for the most efficient operation at high temperature. The goal is 50 degrees C-cm/W thermal resistivity in a wet condition, and 100 degrees C-cm/W thermal resistivity in the dry condition.) However, river sand, widely used as a backfill material, has 150 degrees C-cm/W thermal resistivity in the wet condition, and is more than double the wetted one in a dry condition. Experimental tests present a combination of crushed rock, recycled sand, stone powder, slag, and floc as an alternative backfill material for optimum heat transfer efficiency and construction waste recycling. The optimized backfill material is then validated by field tests and numerical analysis.