This paper first briefly overviews the production and use of iron and steel slag in Japan and the quality requirements for use in road construction imposed by the Japanese industrial standard, followed by an outline of the mainstream structural design method of asphalt pavement. Then, presented is the compaction properties and uniaxial compressive strength of hydraulic, graded iron and steel slag base-course material produced at five different manufacturers. Series of uniaxial compression tests were carried out on the specimens cured up to 730 days. As the results, it is shown that there are large variations in the density of solids and the compaction properties among those five base-course materials, that those five base-course materials show uniaxial compressive strength in a wide range for each curing time, that the way the uniaxial compressive strength increases with time differs among them, and so on. Its relationship with the resilient modulus for each of the five base-course materials is also referred.

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Cyclic plastic deformation of subgrade and other engineered layers is generally not taken into account in the design of railway bridge transition zones, although the plastic deformation is the governing factor of frequent track deterioration. Actual stress behavior of fine grained subgrade/embankment layers under train traffic is, however, difficult to replicate using the conventional laboratory test apparatus and techniques. A new type of torsional simple shear apparatus, known as multi-ring shear apparatus, was therefore developed to evaluate the actual stress state and the corresponding cyclic plastic deformation characteristics of subgrade materials under moving wheel load conditions. Multi-ring shear test results has been validated using a theoretical model test results; the capability of the multi-ring shear apparatus for replicating the cyclic plastic deformation characteristics of subgrade under moving train wheel load conditions is thus established. This paper describes the effects of principal stress rotation (PSR) of the subgrade materials to the cyclic plastic deformation in a railroad and impacts of testing methods in evaluating the influence of principal stress rotation to the track deterioration of rail track.

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In situ investigation of the soil characteristics offers significant promise for providing a reliable and economical method for obtaining strength and stiffness characteristics associated with pavement design. The investigation of the compressibility and compaction properties of a layer of soil below subgrade of an internal road was carried out in Salt lake campus of Jadavpur University. A cut section of 990 mm depth below existing ground level (EGL) was prepared for subgrade of that internal road construction. The characteristics of top subgrade soil are silty sand and foundation soil below subgrade is silty clay to clayey silt in nature upto a substantial depth. Field tests reported in this paper were carried out by flat dilatometer, field CBR using loaded reaction truck and truss both. Dynamic cone penetrometer(DCP) test was also done for a preliminary research program for evaluation of newly compacted subgrade support characteristics. Flat dilatometer (DMT) was used to determine the different properties and moduli of foundation soil below the subgrade and also field CBR, DCP and field compaction tests were carried out to determine the bearing strength and compaction properties. After completion of numerous dilatometer investigations the box was excavated in the field allowing for conducting field CBR test at different depth below the subgrade. Field and DCP CBR versus dilatometer index are plotted for moisture and density variations at different depth.

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The excessive loading generated from the train may cause the subgrade failure in the railway. Subsequently, the failure of subgrade leads to the change in the geometry of the rail. This paper represents the application of a dynamic and static cone penetrometer (DSCP) to evaluate the strength in the railway substructure. The DSCP, which consists of an outer pipe and an inner cone, is designed for the penetration into the ballast and subgrade, respectively. For the ballast, the outer pipe mounted with an accelerometer and four strain gauges is used to estimate the energy transferred into the head of pipe. During the penetration of the outer pipe, dynamic cone penetration indexs (DCPI) are recorded and can be corrected with the transferred energy. To evaluate the soil strength in the subgrade, the inner cone, which is mounted with four strain gauges, is used. For the field application of the DSCP, the dynamic and static cone penetration tests are performed at two positions. The results show that the corrected DCPI with the transferred energy is independent on the impact system. Furthermore, in the subgrade, the inner cone of the DSCP provides the soil strength profile with a high resolution, in terms of the cone tip resistance. This study suggests that the dynamic and static cone penetrometer may be effectively used for the characterization of the substructure in the railway.

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In this study, limit equilibrium methods were focused to evaluate lateral resistances of railway ballasted tracks. Lateral resistances under single-sleeper pull-out loadings as well as those under track-panel pull-out loadings were estimated for various shapes of sleepers. The lateral resistances were compared with those obtained from model tests. It was found that the limit equilibrium methods could well predict lateral resistances not only for a rectangular parallelepiped-shape sleeper but also for winged-shape sleepers having rectangular or trapezoid cross sections. It was also found that lateral resistances of various numbers of sleepers under track-panel pull-out loadings could be reasonably predicted by the methods.

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Recently in Japan, railway ballasts have been flown out several times by heavy or intense rainfalls. However, the mechanism has not yet been investigated in detail, so that the risk and the countermeasures cannot be reasonably proposed. Therefore, in this research, model tests and numerical analyses were conducted to investigate the flow-out mechanism. It was found that the seepage characteristics of ballast beds can be expressed based on Forchheimer law not on Darcy law. Progressive failures were observed in the model tests. It was also found that the stability of the ballast beds can be reasonably explained by the proposed micro-mechanic approach.

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