The RS method is a new pile driving method that is well suited to the construction of foundations in port areas. In such areas, oftentimes an impact hammer cannot be used because the noise and ground vibration caused by the hammer are problematic for neighboring industrial plants and residential areas. However, the bearing capacity of piles driven by vibratory pile driving with water jetting or cement milk jetting is uncertain, although these methods can decrease the noise and ground vibration compared to the impact hammer. The RS method drives the pile using a vibratory hammer with water jetting and forms a soil cement block on the tip with cement milk jetting. In this paper, we show the bearing performance by analyzing the axial loading for 600 ~ 1300mm diameter piles driven by the RS method. It was found that the bearing capacity of the test piles was determined by the soil resistance, and the strength of the soil cement block, which was estimated by an unconfined compression test, is much higher. This result indicates that the soil cement block is well-constructed, and if a pile is driven into soil that is harder than the soil used in the test, it is possible the pile will even have higher bearing capacity. Furthermore, the feature of the resistance mechanism of piles driven by the RS method is believed to be the high shaft resistance in the soil cement block.

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To study the bearing capacity of cemented layer overlaying dredged sediment, a series of plate load tests were carried out by bearing on double-layered systems formed by an artificially cemented top soil layer. And three different top layers overlaying an ultra-soft dredged sediment had been studied. Applied pressure-settlement behavior was observed for tests carried out using circular steel plates ranging from 50 to 150 mm diameter on top of 40 to 80-mm-thick artificially cemented layers. The effects of cemented layer unconfined compressive strength (UCS), thickness, plate size, and the sediment undrained shear strength on the ultimate bearing capacity (UBC) of this foundation were studied. Test results demonstrated the UBC increases linearly with cemented layer UCS strength, cemented layer thickness, DS undrained shear strength, and the ratio of cemented layer thickness to plate diameter. The UBC decreases linearly with the plate diameter. The pressure and settlement curves can be normalized in terms of pressure/pressure at 3% settlement (p/p 3%) versus settlement-to-diameter (δ/D). This result can be used to estimate the pressure-settlement curves for footings of different sizes on different thicknesses of a cemented upper layer by a single curve.

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Earthquakes have occurred globally over the last two decades, which have resulted in an increased expectation of acceptable performance for bridge structures during seismic events. Many research projects have been performed to assess the degree of structural damage especially upper structure of bridges. However, a few researches are available on the pile foundation systems and their response to earthquakes especially for a pile to pile-cap connection. When a pile-cap is loaded, moment and axial loads are transferred to the pile through the pile to pile-cap connection. There is uncertainly with regards the portion of the loads the connection experiences due to the inability to effectively monitor the forces the connection experiences during loadings. In order to investigate behavior of the pile to pile-cap connection for steel pipe piles subject to axial and uplift loads, full scale tests were conducted, and their key factors were considered from test results.

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This study explores the production of a new type of pile. This new spiral pile is made of a twisted steel plate, creating a continuous spiral shape. Before starting the large-scale production of these piles, it is necessary to experimentally determine their bearing qualities, which are related to installation method. It is also necessary to develop an analytical model to determine their bearing capacity. The purpose of this study is to determine the bearing qualities of the spiral pile and the behavior of the surrounding ground. Considering this, the first objective is to examine the incidence of the shape of the pile. The installation method and penetration resistances are thoroughly discussed on the basis of the results of static loading tests using model piles. The static penetration tests were conducted under various shaft rotary conditions at the model pile head. It was confirmed that the shaft rotary condition has a significant impact on the penetration resistance and vertical bearing capacity of the spiral pile. The second objective is to show the behavior of the ground before and during penetration using X-ray computerized tomography (CT). An industrial X-ray CT scanner was used to observe changes in the density of the sand surrounding the spiral piles before and during penetration. The disturbance area of the ground surrounding the spiral pile was observed using CT images; the images revealed that the disturbance area surrounding the spiral pile was significantly affected by shaft rotary conditions.

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Foundations of structures like earth retaining structures, abutments, waterfront structures, machines, oil/gas platforms in offshore areas, etc. are subjected to eccentric and/or inclined loading. The contact pressure below the foundation does not remain uniform due to eccentric load as the foundation tilts. Response of a rectangular foundation on the surface of the ground modeled as non-linear Winkler model is evaluated for its dependence on eccentricity of load, subgrade properties, etc. The ultimate bearing capacity of eccentrically loaded foundation is not only a function of width of the footing and eccentricity of load but also depends on the compressibility of the foundation soil. The ultimate load ratio of eccentrically loaded foundation with respect to concentrically loaded foundation is estimated based on both Meyerhof’s method and the proposed approach. The predicted values of ultimate load ratio compare well with the measured ones.

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Analytical elasticity solutions provide an efficient means of performing a first approximate analysis in foundation engineering. One of the well-known basic solutions is Mindlin's solution to the stress and displacement induced by a point load at an embedment depth in a half-space. This solution is more superior but less widely used than Boussinesq's solution for a point load at only the boundary of half-space. To promote the applications of Mindlin's solution, its vertical stress equation is integrated to obtain an explicit formula for calculating vertical stresses at any arbitrary point. The stresses are induced by uniformly and triangularly distributed vertical pressure, which is exerted over a rectangular area in the interior of a homogeneous, isotropic, elastic half-space. It shows that the vertical stress decreases as the embedment depth of loaded area increases.

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In the present study an analytical procedure is developed, based on finite element approach, to determine the bending moment and lateral deflection response of a free headed single pile with floating tip embedded in both dry and saturated cohesionless soils subjected to combined action of vertical and lateral loadings, using the modulus of subgrade reaction method. Also the numerical results using MIDAS GTS are obtained to validate the proposed analytical solution. It is observed under static conditions, when the vertical load is increased from zero to the ‘ ultimate’ pile capacity at 0.03D deflection level (where D is the diameter of the pile), the lateral load carrying capacity of the fixed headed and free headed flexible piles is increased by 43.27% and 26%, respectively embedded in dry dense sand. Similarly for fixed headed piles embedded in dry and saturated loose sand, the bending moment is increased by 25% and 27%, respectively when vertical loads varies from zero to ultimate pile capacity for a constant lateral load of 200kN.Thus the above analysis is useful for practical design purpose to estimate the lateral load carrying capacity of a single pile by knowing the allowable deformation and vertical load acting on the pile.

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