It is well understood that rainfall infiltration decreases the unsaturated shear strength of soil slope due to reduction in matric suction as the wetting front moves through it. However, how much the matric suction is reduced that may affect slope stability results is still unknown. The paper presents the numerical results of wetting front depth, matric suction and stability results in term of reliability index for a single rainfall intensity. The analyses are for five soils using the modified Mohr-Coulomb failure criterion in conjunction with a finite element saturated-unsaturated seepage model. The numerical results show that the matric suction results are differently affected for soils with rainfall infiltration. The change in reliability index result is insignificant as long the soil remains unsaturated as the wetting front moves. The reliability index results are however become noticeable if the infiltrated rainfall produces saturation and positive pore-water pressure. The difference in results may be attributed to the wetting front depth and its saturation that depends on saturated-unsaturated hydraulic conductivity and matric suction head.

Soil liquefaction, caused by increased porewater pressure, is a significant risk in seismically active areas, impacting infrastructure stability and challenging liquefaction forecasting due to intricate nonlinear interactions. This study proposes a soft voting ensemble classifier (SVEC) that integrates CatBoost Classifier (CBC), Random Forest Classifier (RFC), and Gradient Boost Classifiers (GBC) to predict liquefaction using Standard Penetration Test (SPT) data. The dataset of 540 soil and seismic parameters was utilized to develop SVCE. The dataset incorporates depth, SPT-N60 values, Fine Content of soils (FC), Ground Water Table (GWT), Effective Stresses of Overburden (ESO), Total Stresses of Overburden (TSO), Earthquake magnitude (M_w), and Peak Ground Acceleration (PGA), as input factors for liquefaction prediction. The proposed model was evaluated through performance metrics (Accuracy, Recall, Precision, and F1-score), confusion matrix, sensitivity analysis, feature importance, and Shapley additive explanation (SHAP) analysis. SHAP improves the reliability of ensemble techniques in liquefaction analysis by highlighting the most critical input features, such as PGA, SPT-N60, FC, and GWT. tenfold cross-validation and precision-recall curve confirms the SVEC model’s robustness, achieving a high accuracy of 99.38% in accurately predicting liquefaction.

Human activities have had a profound impact on the environment, particularly in relation to surface erosion and landslides. These processes, which are natural phenomena, have been exacerbated by human actions, leading to detrimental consequences for ecosystems, communities, and the overall health of the planet. The use of lignin (LIG) as a biopolymer soil additive material is regarded as an eco-friendly solution against soil erosion and slope failure which holds immense promise. However, significant research gaps currently hinder a comprehensive understanding of its mechanisms and effectiveness. Experimental studies offer a robust platform to address these gaps by providing controlled conditions for assessing soil stability, exploring mechanisms, and evaluating adaptability. Bridging these research gaps will contribute to the development of innovative and sustainable strategies for mitigating soil erosion and preventing slope failure, thereby promoting environmental resilience and resource conservation. This study aimed to investigate the effect of the LIG biopolymer on mitigation of soil erosion, slope failure and the enhancement of soil strength by conducting laboratory tests (UU triaxial, unconfined compressive strength (UCS), and soaking) as well as flume experiments under uniform rainfall events. The alterations in the engineering characteristics and erosion resistance of silty soil mixed with a LIG additive at concentrations of 1% and 3.0% by weight have been examined. The results show that the LIG-treated samples demonstrated an enhanced resistance to surface erosion and an enhanced prevention of slope failure, as well as improved shear stress, cohesion, stiffness, and resistance to water infiltration.

Several empirical and analytical methods have been proposed to estimate the elastic settlement of shallow foundations based on the elastic continuum theory. Previous methods have been generally proposed for circular foundations, its approach of using equivalent diameter was found less reliable for foundations of aspect ratio L/B > 2. This paper presents a three-dimensional numerical analysis to extend and improve the applicability of settlement influence and correction factors for shallow foundations of large aspect ratios. First, a methodical optimization and verification program was conducted to determine and verify a reliable model for numerical analysis. Using the verified model, two new sets of settlement influence factor and correction factor for foundation roughness of circular and rectangular foundations were then derived and proposed. A correction factor chart for the foundation rigidity of rectangular foundations was also proposed. Finally, the applicability of the proposed factors in this study was verified by comparing calculated settlements using the proposed factors along with the measured values from two raft foundations. The proposed approach was indicated to be a better alternative for foundations of L/B > 2.

The improvement of soft clay and dredged soils to carry structures is increasingly important. In this study, the dynamic behavior of a crushed stone foundation wall in clay soil was analyzed using a 1g shaking table test. The response accelerations and spectra for three input ground motions were analyzed relative to the distance from the foundation wall, confirming that the acceleration was damped from the outside. The acceleration according to the distance from the wall was not significant under long-period motions, while different responses were obtained under short-period motions. The increased ground stiffness provided by the crushed stone wall lowered the natural period of the ground, and the acceleration amplification under short-period seismic waves was larger than that under long-period waves. Finally, equations were derived to describe the relationship between the acceleration amplification ratio and distance from the wall. The slopes of the proposed equations are larger under shorter periods, implying that the change in acceleration change with distance from the wall is more significant under shorter periods. The results of this study can be used to inform the design of soft soil improvements and the structures built atop them.