Electrokinetic remediation (EKR) has shown great potential for the remediation of in situ contaminated soils. For heavy metal-contaminated soft clay with high moisture content and low permeability, an electrokinetic remediation method with electrolytes placed above the ground surface is used to avoid issues such as electrolyte leakage and secondary contamination that may arise from directly injecting electrolytes into the soil. In this context, using this novel experimental device, a set of citric acid (CA)-enhanced EKR tests were conducted to investigate the optimal design parameters for Cu- and Zn-contaminated soft clay. The average removal rates of heavy metals Cu and Zn in these tests were in the range of 27.9–85.5% and 63.9–83.5%, respectively. The results indicate that the Zn removal was efficient. This was determined by the migration intensity of the electro-osmotic flow, particularly the volume reduction of the anolyte. The main factors affecting the Cu removal efficiency in sequence were the effective electric potential of the contaminated soft clay and the electrolyte concentration. Designing experimental parameters based on these parameters will help remove Cu and Zn. Moreover, the shear strength of the contaminated soil was improved; however, the degree of improvement was limited. Low-concentration CA can effectively control the contact resistance between the anode and soil, the contact resistance between the cathode and soil, and the soil resistance by increasing the amount of electrolyte and the contact area between the electrolyte and soil.

Soft clay contamination is an increasingly global issue with significant implications for land development and human health. Electrokinetic remediation (EKR) has demonstrated significant potential for cleaning contaminated soils. It is crucial to develop efficient processes that minimize environmental impact and reduce costs. A series of citric acid (CA)-enhanced EKR tests were conducted using a novel experimental setup, with the electrolyte positioned above the soil surface, to examine the impact of four different electrode arrangements on the effectiveness of EKR. The position of the electrode end had a significant impact on the migration of ions in the anolyte and catholyte, which in turn affected the volume reduction in the anolyte, the magnitude of the current, and the migration of heavy metals. The electrode arrangement mode c (electrodes suspended in the electrolytes) can enhance the migration of the anolyte and reduce the drainage of the soil, making it an effective measure for improving the removal rate of heavy metals. After the heavy metal remediation is complete, the bearing capacity of the soil should be increased. Changing the electrode arrangement to mode d (anode suspended in the anolyte, a very small part of the cathode inserted into the soil) is an effective measure for reducing the soil water content and improving soil strength.

This study investigated a novel electrolyte chamber configuration for heavy-metal-contaminated fine-grained soil to reduce the leakage of electrolyte solution and alleviate secondary pollution, finally promoting the electrokinetic remediation (EKR) potential to be scaled up for application. Experiments were conducted on clay spiked with Zn to investigate the feasibility of the novel EKR configuration and the effect of different electrolyte compositions on the electrokinetic remedial efficiency. The results show that the electrolyte chamber situated above the soil surface is promising for the remediation of Zn-contaminated soft clay. Using 0.2 M citric acid as the anolytes and catholytes was an excellent choice for pH control in the soil and the electrolytes. Through this, the removal efficiency in different soil sections was relatively uniform and more than 90% of the initial Zn was removed. The supplementing of electrolytes resulted in the water content in the soil being distributed evenly and finally sustained at approximately 43%. Consequently, this study proved that the novel EKR configuration is suitable for fine-grained soil contaminated with Zn.

This paper presents the design and construction of vacuum preloading incorporated with electroosmosis (VPE) engineering application for the treatment of soft soil on complex terrain for sluice foundation excavation in order to reduce the amount of cement used in construction. Monitoring was conducted during the VPE treatment and laboratory geotechnical tests were carried out once the treatment came to an end. Results show that the electrification mode has a significant influence on electric energy consumption. Stepped-up voltage helped in saving electric energy while electrode conversion consumed a lot of electric energy. The dispersion of soil parameters became larger after VPE treatment. The stability of physical parameters is better than the mechanical parameters, and the latter is better than the deformation parameters. Soil water content has a linear relationship with density and compression coefficient. The given linear fitting equations can help in simplifying the calculation and acquisition of these indexes. Although the mean values of the soil index parameters slightly improved, their coefficient of variation (COV) significantly increased. These locations with improved index parameters scattering in the construction site ensured that the subsequent construction tasks such as pit slope and excavation were successfully realized in this area.

The coefficient of lateral earth pressure at rest, K₀, is an essential parameter for analyzing earth pressure distribution and the safe reliability of structures in geotechnical engineering. This paper presents a series of numerical one-dimensional compression tests on granular soils with particle size distribution (PSD) and rolling resistance (RR) effects using a real-particle 3D discrete element model. The corresponding macro–micro behaviors are investigated in a parallel way. Both PSD and RR affect K₀ and the related compression characteristics. A higher coefficient of uniformity (C_u) or rolling resistance coefficient (μ_r) results in a monotonic decrease in the mean coordination number, and too much consideration of RR makes the mean coordination number less realistic in a particle system. The influence of PSD is more sensitive to the local-ordering structure and contact force network than the RR. The inhomogeneity of normal contact forces enhances as C_u increases and slightly reduces as μ_r increases. The strong contacts are much more anisotropic than the weak ones. Specimen with lower C_u or higher μ_r induces higher anisotropy and more strong contacts during compression, in which a lower K₀ is measured. A unique macro–micro relationship exists between K₀ and deviatoric fabric when strong contacts are considered only.