Foundations

Foundation engineering emerged as a discipline of modern engineering science in 1940s. Design and analysis as well as practice of foundation engineering have made a significant progress up to the present time. This paper gives an overview of the development of foundation engineering, mainly referring to papers published in Soils and Foundations. The paper describes the theoretical development of foundation analysis and a recent increasing trend of foundation practice of adopting various hybrid foundations. The paper points out the importance of environmental considerations in foundation design and practice, including low noise and vibration reduction, reuse of existing foundations and use of natural energy through foundation elements. The paper then provides authors’ views of future directions in foundation studies and practice.     

Improvement Properties of Cohesion-Less Soil Using Recycled Bassanite

Solid waste management is a serious problem over the world. Therefore, reduction, re-use and recycling of waste have become major issues in recent days. Gypsum waste plasterboard is considered one example of these waste materials. This study evaluates the use of recycled bassanite, which is derived from gypsum waste plasterboard, to enhance the performance of two types of cohesion-less soil. Recycled bassanite was utilized as a stabilizing agent to improve both compressive and splitting strengths of the tested soil. The effect of bassanite content, soil type, water content and curing time were investigated to explore the behavior of treated soil with recycled bassanite. Test results showed that increase of bassanite content is associated with increase in optimal moisture content, while no significant increase in the dry unit weight was observed. Both compressive and splitting tensile strengths enhanced with the additives of recycled bassanite. The increase of bassanite content had a more significant effect on the compressive strength compared with the effect on tensile strength. The use of recycled bassanite to enhance the strength of sandy soil had a more significant effect compared with silty soil. The effect of curing time on the strength of treated samples was more significant in early curing ages compared with late curing ages. The strength decreased significantly in case of stabilized samples prepared with water content at the wet-side of the compaction curve. However, insignificant decrease in the strength of the stabilized sample was detected with moisture content at the dry-side of compaction curve. This research meets the challenges of our society to reduce the quantities of gypsum wastes, producing useful material from waste materials that will help to a sustainable society.     

A three-dimensional soil–water coupled FE analysis of hollow cylinder test concerning non-uniform deformation

The hollow cylinder shear test is somewhat controversial due to its non-uniform stresses and strains, and has been analyzed by simple theoretical methods and two-dimensional FE calculations. In this paper, the hollow cylinder test under strain control was carried out numerically by treating the specimen as a three-dimensional initial-boundary value problem considering the inertial forces. At first, besides the known nonuniform strain, the non-uniformities of excess pore water pressure and overconsolidation ratio have been shown to benefit from a soil–water coupled analysis that employs the SYS Cam-clay model. Then, the influence of the specimen geometries, including wall thicknesses, heights and outer diameters on the non-uniformity was investigated sequentially. A new method for evaluating non-uniformity was proposed, which is suitable for the three-dimensional analysis. The response under a uniform deformation field, which is indicated by “the perfect path”, was presented to draw a comparison with the apparent behaviors, with non-uniformities taken into consideration. It should be noted that there is a critical height to prevent failure at the specimen ends according to the apparent behavior. Finally, the torque-controlled experiment indicated that 4 ribs could not transfer the torque reliably while 6 or 8 ribs were feasible.     

Surface durability of powder-forged roller treated by shot peening

To investigate the influence of shot peening on the surface durability of powder-forged rollers, the case-hardened powder-forged rollers with a forging density of 7.5 g/cm³ treated by the single shot peening and the double shot peening were fatigue-tested under a sliding-rolling contact condition. The surface roughness, the surface hardness and the surface compressive residual stress of the rollers were increased by the shot peening. In addition, the pores near the roller surface were deformed by the shot peening. The failure mode of all the test rollers was spalling due to subsurface cracking. The fatigue lives of all the test rollers were improved by the shot peening, and that of the test roller S08, which was shot-peened with the hardest steel shots in this experimental range, was especially improved. The surface durability of the test roller S08 was also most improved by the shot peening. Cracks became difficult to occur and propagate under the roller surface since the pores near the roller surface were deformed by the stronger shot peening. In this study, double shot peening, which generally restrains the increase in surface roughness, was not particularly effective for the improvement in the surface durability of the powder-forged rollers, because the influence of tangential force on fatigue was not always great in a case of subsurface cracking.     

Structures and electronic properties of surface/edges of nanodiamond and nanographite

The structure, electronic and magnetic properties of nanodiamond and nanographite/nanographene are investigated. Detonation nanodiamond particles that are covered with amorphous graphitic composites are hydrothermally treated to remove the graphitic surface composites and to terminate the surface carbon atoms with hydrogen. The number of localized spins of dangling bonds and the hydrogen concentration increase upon the increase in the hydrothermal treatment time up to 40 h. Above 40 h, both drop discontinuously, a surface structural reconstruction was suggested. The creation of dangling bonds and an incomplete hydrogenation of the surface carbon atoms destabilize the surface, resulting in the structural reconstruction. Nanodiamond particles are thermally converted to nanographite/nanographene. A single nanographene sheet is successfully prepared by heat-treating nanodiamond particles. The edge of graphene sheet with its edge carbon atoms being hydrogen-terminated is investigated by UHV-STM/STS. Zigzag edges are found to have non-bonding π-state of edge origin, in good agreement with theoretical prediction.     

Remarkable effect of addition of In and Pb on the reduction of N2O by CO over SiO2 supported Pd catalysts

The effect of addition of In and Pb on the reduction of N₂O by CO was studied over SiO₂ supported Pd catalysts, using a closed gas circulation system as well as in-situ infrared spectroscopy. Formation of intermetallic compounds such as Pd_0.48In_0.52, Pd₃Pb and Pd₃Pb₂ was observed which caused a drastic enhancement of the rate of N₂ formation. The infrared spectroscopic analyses revealed a weakening of the adsorption strength of CO on Pd metal by the formation of intermetallic compounds, which is likely the main reason for the enhancement of the reaction rate. From a kinetic investigation as well as in situ FT-IR observation during the N₂O-CO reaction, a redox mechanism was proposed involving the oxidation of the surface by N₂O followed by its reduction by CO. Over Pd/SiO₂, the former process seems to be the rate limiting step because of the inhibition of N₂O activation by strongly adsorbed CO. By adding In or Pb, the rate limiting step shifted to the latter process, which resulted in a large enhancement in the rate of N₂ formation.     

Effects of blasting parameters on removability of residual grit

This article shows the quantitative evaluation of the residual grit on a blasted substrate, and the removability of the residual grit is examined. Carbon steel plates were blasted by white alumina grit with mean diameters of 338 to 1106 μm. The velocity and the number of grit particles were measured during blasting. The residual grit was removed from a substrate surface by the dissolution of the blasted substrate surface. A mixed acid solution was used as the dissolution solution. The residual grit weight was 7 to 17 g/m². The amount of the residual grit and the penetration depth of the embedded grit increased with increasing grit size. The penetration depth was 5 to 9% of the mean diameter of the grit. The residual grit weight and the penetration depth increased with the increase of the momentum of the grit particle. This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials Park, OH, 2006.     

The oxidation properties of fourth generation single-crystal nickel-based superalloys

The fourth-generation nickel-based single-crystal superalloys, which contain large amounts of refractory metals for strengthening and platinum group metals for topologically close-packed phase prevention, show excellent high-temperature strength. However, these alloying elements seem to decrease high-temperature oxidation resistance. In this study, nickel-based superalloys with various amounts of tantalum, rhenium, and ruthenium were examined in isothermal and cyclic exposures at 1,100°C to investigate the effect on the oxide growth rate and resistance to scale spallation. Ruthenium and rhenium were found to degrade the oxidation resistance by the vaporization of their oxide. Tantalum-rich oxide in the spinel layer acts to stabilize ruthenium and rhenium oxide in the scale. The addition of hafnium and yttrium is effective in improving the oxidation resistance of ruthenium-containing nickel-based superalloys.     

Numerical and Experimental Analysis for the Small Vibration of Aerostatic Guideways

Aerostatic guideways have been used in many fields and are absolutely essential for ultraprecision machining. Recently, with increasing demand for ultraprecision devices, the accuracy of 1nm or less has become necessary. On the other hand, conventional aerostatic guideways are not designed considering the influence of small vibration which occurs by supplying air. This vibration is hampering the improvement in accuracy. In this study, a new design of the outlet of orifice restrictors is proposed from the result of numerical analysis and its effect is examined numerically and experimentally. The mechanism for the occurrence of small vibration is analyzed and the methods to suppress the small vibration are proposed.     

Femtosecond-laser-induced nanostructure formation and surface modification of diamond-like carbon film

This paper reports the pump and probe experiment for in situ reflectivity measurements in the femtosecond laser ablation that brings about nanoscale modification of diamond-like carbon (DLC) film. The characteristic reflectivity changes observed demonstrate that the formation of periodic nanostructure is preceded by a change in bonding structure of DLC in the ablation at low fluences. We have observed a coherent nonlinear wave-mixing signal that can resolve the ultrafast interaction processes for the nanoscale modification on the film surface. Based on the results obtained, a model of the interaction process is proposed.