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Negative skin friction (NSF) is an undesirable effect of piles observed in the dredged slurry of coastal reclamation areas. Herein, a testing framework was developed to investigate the pile NSF development pattern in the Wenzhou dredged slurry treated using the vacuum preloading drainage reinforcement (VPLDR) method. The vacuum pressure (VP) loss in field projects can cause variations in pressures in the treatment area and the VPLDR duration. A method to quickly quantify the treatment effectiveness of VPLDR is needed to ensure consistency. Two VPLDR cases with varying negative vacuum pressures (NVPs) and duration time were implemented to determine the main operating strategy for controlling the artificial consolidation effect. The pore water pressure (PWP) of soil was found to be associated with the undrained shear strength (Su) and was the primary indicator of the VPLDR effectiveness. The moisture content and water discharge only slightly influenced the Su magnitude. The equivalent reinforcement effect was achieved in the field VPLDR treatments by maintaining a constant PWP. Four tests on the model pile subjected to ground surcharge loading were conducted to study the NSF under various soil specimens and axial loading. NSF was observed in piles with surcharge loading and was reduced significantly in the reinforced slurry by the VPLDR. The surcharge-induced pile settlement can be decreased further with a small level of pile top load. The appropriate VPLDR and top load can weak the NSF caused by stacking. Therefore, these factors should be considered during pile construction in reclamation areas to restrain NSF. [ABSTRACT FROM AUTHOR]

This article examines the stability of retaining walls with relief shelves compared to the conventional cantilever wall using limit analysis integrating with the finite element method. The performance of such walls subjected to an incremental static uniformly distributed surcharge loading on the backfill surface is accessed in the terms of the magnitude of the surcharge carrying capacity of the walls before the incipient failure of the overall structure. From the analysis, it is noted that the provision of an appropriate number of relief shelves and their suitable locations and widths to the wall can bring significant improvement in the stability of the retaining wall compared to a wall without a relief shelf. Furthermore, it is noted that the width and location of the relief shelf are the major governing factors that are susceptible to modify the shape of the potential failure plane, the failure mode of the wall, and the backfill surface settlement profile. To maximize the stability of the wall subjected to static loading on the backfill surface, recommendations are laid for the optimum location and width of the relief shelves for a given height of the wall. [ABSTRACT FROM AUTHOR]

This study conducted parametric analyses to investigate the influence of structural loading (pile-head loading) on the development of negative skin friction in friction single piles and friction-end-bearing single piles in consolidating ground. Numerical effective stress-based mechanical-flow analysis models were built in ABAQUS software. The appropriateness of the modeling approach was verified by applying it to simulate a field model test described in the literature. For small surcharges, pile-head loading considerably reduces the depth of the neutral plane and therefore drag load for the friction pile. Under the same pile-head loads, the reduction in total drag load for the friction-end-bearing pile is smaller than that for the friction pile. However, when the friction-end-bearing pile is subjected to larger pile-head loads, the degree of total drag load reduction is comparable to that of the friction pile. Considerable pile-head displacement occurs under the combined action of pile-head and surcharge loadings. In contrast to the friction pile, the friction-end-bearing pile, because of the greater stiffness and strength of its bearing stratum, exhibits a significant reduction in negative skin friction, no bearing failure, and a smaller pile-head displacement when it is subjected to large pile-head loading. [ABSTRACT FROM AUTHOR]

Water level drawdowns that occur outside and inside a fully, or partially, submerged slope will change the hydraulic gradient and enhance seepage forces, and may thus lead to slope instability and collapse. Existing research on this stability issue has primarily focused on the use of linear failure criteria and the associated flow rule. Little attention has been given to the effects of nonlinearity and the nonassociated plasticity of geomaterials, and of surcharge loading on slope stability. However, these conditions are more realistic for real-world cases. This study addresses this knowledge gap. The limiting surcharge on the top of submerged slopes subjected to water drawdown is analyzed in terms of nonlinearity and dilation effects using a limit analysis method. The optimal solutions were sought through optimization. The proposed method and its assumed failure mechanism were validated by comparing the results of the proposed method with results from finite element and finite element limit analysis. Parametric analysis and a case study are presented and indicate that as the water level difference increases, the bearing capacity of the slope decreases. In addition, it was found that the dilatancy effect has an effect on slope bearing capacity and that the inclusion of nonlinear effects enables better results. [ABSTRACT FROM AUTHOR]

The safety factor of the slope subjected to wedge failure under surcharge load and uplift forces was obtained using an analytical model. A detailed parametric study conducted for the physical slope involved examining the impacts of the surcharge loads and uplift forces acting along the joint planes due to water pressure on the safety factor of the slope subjected to wedge sliding. The study results indicated that the safety factor of the slope susceptible to wedge sliding decreases with an increase in the surcharge loads and the uplift forces acting along the joint planes due to water pressure. The reduction in the safety factor due to an increase in the surcharge load is independent of the uplift forces acting along the joint planes. The rate of deterioration in the stability of the rock slope susceptible to wedge sliding depends on the rate of increase in the surcharge loads and uplift forces acting along the joint planes due to water pressure. The proposed expression can be useful for analytical stability analyses of the rock slopes subjected to wedge sliding induced by the surcharge load and uplift forces. [ABSTRACT FROM AUTHOR]

A series of field tests were conducted to examine the behavior of pile foundation subjected to adjacent surcharge loading in deep soft soils. The emphasis was on the pile deflection, bending moment, soil horizontal displacement and lateral earth pressure acting on the piles under different surcharge loading conditions. It was found that among the surcharge loading distance, intensity and width, the surcharge loading distance was the most significant factor affecting the adjacent piles in deep soft soils. The springback process of piles subjected to adjacent surcharge loading after unloading was a slow process changing with time. The mean lateral earth pressure on the pile facing the surcharge loading is slightly larger than that opposite to the surcharge loading. The pile bending moment and mean lateral earth pressure acting on the pile decrease with time due to the consolidation process of soft soil. 3D finite element model in ABAQUS is established to study the influence of consolidation process of soft soil on piles subject to adjacent surcharge loading. [ABSTRACT FROM AUTHOR]