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When the ground would be excavated and retained adjacent to the existing structure, earth pressure acting on the rigid wall of the existing structure could be changed depending on its separation distance from the retaining wall, its wall friction, and the deformation of retaining wall. Model tests were conducted in the uniform sandy ground for various separation distances and wall frictions. Test equipment consisted of the model test box, the rigid wall and the earth retaining wall. Location of the retained earth wall was varied. They were 0.4H, 0.8H and 1.2 H (H is the height of rigid wall). Friction angle of the rigid wall was varied. They were 0, ϕ/3, 2ϕ/3. The earth pressure on the rigid wall was changed under the influence of the deformation of retaining wall, the separation distance of the retaining wall, and the friction of rigid wall. It was found out that the separation distance has more effects on the earth pressure reduction than that of the wall friction. Change of earth pressure on the rigid wall induced by the ground excavation adjacent to it was affected by the friction of rigid wall, the separation distance, and the displacement of earth retaining walls. Earth pressure on a rigid wall was reduced in a larger amount when the wall friction of rigid wall increased.

Buildings along the flood plain of River Osun, southwest Nigeria, are usually thought of as been a safe haven for residence over the years. But in recent times with vast (increasing) population and growing urbanization, some of the buildings currently experience structural damages not related to constructional designs but rather ground conditions around building foundations. The ground conditions (seepages in this case) and how it influences properties of soils (water moisture, permeability etc.) to support the foundation of buildings. This paper attempts to map out seepages in heterogeneous soils around buildings in Erinle, southwest Nigeria where building cracks probably as a result of water seepages from subsurface through fissures and fractures where noticed. These cracks are a probable manifestation of a weakened foundation that could overtime result to a collapse, hence the need to investigate seepage prone zones. To achieve this, electrical resistivity (ER) and Electromagnetic Ground Penetrating Radar (EM-GPR) surveys were made along affected buildings to map out possible causes of deterioration. Geo-sections (analyzed ER data) shows high resistivity layer (topsoil) underlain by low resistivity layer (weathered basement) confirmed by planer reflections (topsoil) and fairly smooth to smooth reflections (weathered basement) in Radargrams (analyzed GPR data). An integration of the geo-section and radargram produced from ER and GPR data shows that buildings along traverses 1, 2, 3 and 5 is most prone to seepages especially as it exhibits very low anomalously resistivity values (< 25 Ωm) but this is not the case for buildings along traverses 4, 6, 7 and 8.

Pile foundations are adopted if a soil of low bearing capacity extends to a considerable depth or if the structure is heavy or the settlement due to the structure is large. It transfers the load to a strong, stable stratum of soil. The behaviour of soil in slope and piles embedded in it is an elaborated soil-structure interaction problem. This paper presents the results of experimental investigations on a single pile subjected to lateral load by varying relative density of soil in the horizontal and sloping ground with three different slopes of 1V: 2H, 1V: 2.5H and 1V: 3H. The lateral load carrying capacity of the pile is considerably decreased when the lateral load is applied in the direction of the slope. It is found that the lateral load carrying capacity of the pile is increased for higher relative density of sand and the lateral capacity of the pile is greater in flatter slope than in steeper slope. The effect of different slopes on normalized lateral load versus displacement for the lateral load applied in the direction along and against slope is quantified. A set of empirical equations are formulated to determine the deflection, fixity depth and moment for the pile in sloping ground.

The inclusion of sand columns results in enhancing the bearing capacity of clayey soil, increase the rate of consolidation, presentation of liquefaction in loose sandy soils and provide lateral resistance against the horizontal movement. This research aims at investigating the effects of floating columns in clayey soil with silty deposits by developing small scale laboratory models. The effects of sand columns on soils of different shear strengths, slenderness ratio (L/D) of columns were investigated. Group effect was also investigated by varying spacing between the columns. Experimental results were compared with the numerical analysis results. A 15-noded triangular mesh was generated using a finite element tool PLAXIS 2D. Finite element analysis was performed using Mohr’s Coulomb’s criterion considering undrained analysis for soft clayey soil and drained analysis for sand columns. It was concluded that the sand columns can significantly increase the ultimate loading capacity of soft soils. Results show that critical length for floating column ranges from 4 to 5.5 times the diameter of the column, beyond which bulging occurs and loading capacity decreased. The effect of group was also investigated and observed that with high spacing between the sand columns, the group efficiency decreased. The axial capacity of sand columns decreases while increasing spacing between the columns.

Natural and man-made slopes can undergo a retrogressive landslide when subjected to seepage. Studying the mechanism of retrogressive landslides contributes greatly to the employment of effective mitigation approaches. A multi-stage limit equilibrium-based study was performed to explore how the geometry of initial failure affects the progress of a retrogressive, multiple-rotational landslide caused by seepage flow. Seepage-stability analyses were carried out on two silty sand slopes which were previously found to experience successive rotational failures upon raising the water table in centrifuge tests. Analyzed in prototype dimensions were the slope models with the height of 24 cm and inclinations of 45° (1V:1H) and 63.4° (2V:1H) tested at different centrifugal accelerations. According to the tests, the initial shallow failures were assumed to be circular initiating from the face and emerging from the toe of the slopes in the stability analyses. The impact of curvature and length of the initial failure surface (referred to as IFS) as well as the height of the scarp shaped at each failure episode were investigated. The results show that the landslide continues until the slope profile finds a stable curvature. For the landslides that occur in the 45° inclined slope, when the initial failure initiates at a higher elevation on the slope face, the landslide retrogresses further. In addition, with an increase in the length or curvature of IFS, the final retrogression distance decreases. Further, it was observed that the progress of landslides depends on the height of the scarp exposed at each failure episode.

This paper presents a set of new required programmes written in format data using the built-in programming FISH language available in three-dimensional Fast Lagrangian Analysis of Continua software (FLAC3D). These script data files were developed, to overcome difficulties noted during the nailed slope stability prediction. They established to analyse stability of general embankment slope cases under various soil nailing parameters design. To deal with 3D finite difference analysis results in terms of the factor of safety (FOS) and critical slip surface, both 2D finite difference and limit equilibrium (LEM) methods are also conducted. A comparison of the 3D and 2D results indicates that 2D analyses underestimate seriously stability predictions, notably in terms of the FOS. Therefore, it was concluded that, 3D analysis should be used as an alternative to the 2D analyses, even though it requires more time. Some useful conclusions are obtained from this work, which provides a good practice guidance for real life scenarios.

This paper proposes an approach to generate realistic particle shapes considering the major plane of orientation of particles in discrete element modelling (DEM). The particle generation framework includes capturing high-quality scanning electron microscope (SEM) images, followed by image processing and generation of clumps using a commonly used multi-sphere (MS) approach in particle flow code (PFC3D). A set of experimental direct shear tests (DST) and subsequent DEM simulations were performed by incorporating realistic particle shapes. The simulation results show a good agreement with those obtained in the laboratory. In addition, the normal stress showed a significant effect on the structural anisotropy of the granular materials.

This paper aims to understand how anchor cable force evolution laws can improve reinforcement designs. The self-developed weak plane sustained deterioration technology was conducted in the indoor test on the reinforced bedding rock slope containing a linear type weak plane. The force evolution laws of anchor cables with the weak plane sustained deterioration was studied. Furthermore, the theoretical equations were derived on the basis of the rigid assumption of the rockmass and the limit equilibrium method, and the equations have been verified to be reliable through comparison with the test results. The numerical simulations in different rockmass mechanical parameters reveal that the theoretical equations are suitable for hard rockmass. The results indicate that, with the weak plane sustained deterioration, the anchor cable axial forces increase gradually, and the axial force increase is inversely proportional to the length of the free sections. The findings could provide the theoretical guideline for the pre-stress safety reserves during the reinforcement designs of anchor cables in different positions of bedding rock slopes.

Studies in recent decades demonstrate the significant effect of stress configuration (e.g., vertical stress and lateral confinement) on the shear strength or, in this study, the cone penetration test (CPT) results. Addition of a surcharge over the ground changes the stress condition, and consequently, the CPT tip resistance. In this study, the results of different CPTs conducted before and after backfilling with various thicknesses in a land development project were reviewed while focusing on the trend of an increase in CPT penetration resistance due to the additional surcharge. Both pre- to post-fill stress ratios and soil type affect the rise in corrected $${q}_{c}$$ values after backfilling. Moreover, there has always been a sudden increase in $${q}_{c}$$ values around the pre-fill surface in all studied cases. In this study, another approach was derived from the reanalysis of CPT data from a specific site for predicting the post-fill corrected $${q}_{c}$$ from pre-fill results by considering the above-mentioned factor. Likewise, post-fill results were predicted by depth-normalized pre-fill CPT results using Robertson’s normalization method. The proposed approach in this study showed a better match with the site data compared to the normalization method, especially at and around the pre-fill surface.

Ensuring sustainable development of coastal areas need improvement of road embankment infrastructure. Being a byproduct of industry, fly ash may be considered as environment friendly and low cost material for this purpose. However, scarcity of fresh water in coastal areas may compel to use saline water. To investigate the effects of sodium chloride content of mixing water on fly ash and lime mixed compacted sand, a series of the unconfined compression tests have been conducted on 50 mm diameter and 100 mm high specimens. Lime content was varied over a range of 1–5% of dry sand weight and fly ash contents were 9, 15 and 30% of dry sand weight. Besides, 0, 4 and 8% of sodium chloride were mixed with tap water, which were used for preparing specimens at 10% moisture content by compaction method. The specimens were cured for 7, 15, 30 and 60 days by spraying method. Experiment results show that, the unconfined compression strength of fly ash and lime mixed compacted sand increases with the increase in sodium chloride content. However, the long term effect of using saline water in fly ash and lime mixed compacted sand should be investigated, which is out of scope of this study.