No abstract

The surface texture of the interface material plays a significant role in the shear behaviour of soil–continuum interface. This study investigates the influence of surface texture of steel on the shear behaviour of sand–steel interface using different types of steel counterfaces with distinct texturing patterns. The patterns include concentric circular asperities, square-tiled surfaces with equally spaced individual asperities and ruled ribbed asperities oriented parallel, perpendicular and at an angle to the shear direction. The results show that the texturing pattern of the steel counterface significantly affects the shear strength of the sand–steel interface. The peak and residual interface friction angles for the sand–steel interfaces with different texturing patterns (with identical asperity height and spacing) varied from 26·6° to 37·5° and 14·2° to 28·7°, respectively. Moreover, the surface with ruled ribs/asperities inclined at right angle to the shear direction shows the maximum interface shear strength among all the texturing patterns tested. The findings presented herein are imperative for a realistic assessment of the performance of geotechnical structures involving soil–steel interaction.

The irrecoverable deformations in the substructure layers are detrimental to the track stability and demand frequent maintenance. With an escalation in axle-load and traffic volume, the frequency of maintenance operations has remarkably increased. Consequently, there is an inevitable need to predict the long-term behavior of the track substructure layers.This article presents a methodology to evaluate the recoverable and irrecoverable responses of the substructure layers under the train-induced repetitive loads. The present method utilizes an integrated approach combining track loading, resiliency and settlement models. The track substructure layers are simulated as lumped masses that are connected by springs and dashpots.The method is successfully validated against the field investigation data reported in the literature. A parametric study is conducted to investigate the influence of substructure layer properties on the track response. The results reveal that the response of each track layer is significantly influenced by the neighboring layer properties and the incorporation of multilayered track structure enables more accurate prediction of track behavior. The present analytical approach is simple, computationally efficient and may assist the practicing engineers in the safer design of the ballasted track.

17The three-dimensional cellular geoinclusions (e.g. geocells, scrap tires) offer all-around 18 confinement to the granular infill materials, which improves their strength and stiffness. The 19 accurate evaluation of extra confinement offered by these geoinclusions is inevitable for 20 predicting their performance in the field. The existing models to evaluate the additional 21 confinement are based on either plane-strain or axisymmetric stress states. However, these 22 geoinclusions are more likely to be subjected to the three-dimensional stresses in actual 23 practice. This note proposes a semi-empirical model to evaluate the additional confinement 24 provided by cellular geoinclusions under the three-dimensional stress state. The proposed 25 model is successfully validated against the experimental data. A parametric study is conducted 26 to investigate the influence of input parameters on additional confinement. The results reveal 27 that the simplification of the three-dimensional stress state into axisymmetric or plane-strain 28 condition has resulted in inaccurate and unreliable results. The extra confinement offered by 29 the geoinclusion show substantial variation along the intermediate and minor principal stress 30 directions depending on the intermediate principal stress, infill soil and geoinclusion 31 properties. The magnitude of additional confinement increases with an increase in the 32 geoinclusion modulus. The findings are crucial for the accurate assessment of the in-situ 33 performance of three-dimensional cellular geoinclusions. 34 35