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The impact of the use of sand treated with Colloidal Silica (CS) on a model 80 m high-earthfill dam was assessed through numerical modelling. The hydro-mechanical properties of the CS-Treated soil were taken from a previous laboratory study. Different strategies of treatment placement were studied, with increasing volumetric fractions of the dam being replaced by the treated material. Staged construction of the earthwork was simulated to evaluate the horizontal and vertical displacements at critical points within the dam. Different kinematics have been observed, depending on the quantities of CS-Treated material included in the soil structure. Moreover, the use of the treated soil was beneficial in terms of water outflow and upstream slope stability, in correspondence with different water reservoir levels. Different strategic patterns of CS-Treated sand placement are proposed herein to fully exploit the storage capacity of the dam, optimizing its stability. © 2022 American Society of Civil Engineers (ASCE). All rights reserved.

Numerical investigation of laminar counterflow premixed methane-hydrogen-air flames at a low strain rate is presented. Simulations are carried out with a numerical model incorporated with C2 chemical mechanism having 25 species and 121 reaction steps, and with an optically thin radiation submodel. The numerical model is validated using the experimental data reported in the literature in terms of temperature and species concentrations in flames from opposed flow premixed methane-air and hydrogen-air streams. Parametric studies are performed for opposed flowing methanehydrogen and air mixtures. A premixed methane-hydrogen and air with a rich mixture equivalence ratio (1.75) flows from the top duct, and one having a lean mixture equivalence ratio (0.25) flows from the bottom duct. The volumetric fraction of hydrogen in the fuel mixture has been varied from 20 to 80%. The strain rate used in the present study is kept constant at 50 s -1. Variation of velocity, temperature, species concentrations, and net reaction rates of oxygen, methane and hydrogen along the axis for various cases are presented and discussed in detail. Double flame zones are observed for all the cases. The addition of hydrogen to the rich side stream is seen to be effective in modifying the extents of both reaction zones. The reaction rate of methane is seen to be enhanced with the addition of hydrogen. � 2011 by Begell House, Inc.

In rolling contact bearings, contact occurs between the rolling surfaces over a small region. Hence, high contact stresses are induced in the region even under a small load. These stresses are cyclic in nature. Over a long period of time, the surface gets fatigued and surface fatigue wear ensues. The experimental investigation carried out in the laboratory earlier consumed a long time. Therefore, a numerical approach is resorted to in this paper. To study this aspect, the stress field in the contact surface region is analyzed under elastohydrodynamic lubrication with line contact considering the friction effect. The bearing steel microstructure is considered as a mixture of martensite and retained austenite having entirely different mechanical properties and yield behavior. Using finite element analysis, the stress field has been evaluated taking into account two volumetric fractions (8% and 20%) of retained austenite in heat treated AISI 52100 bearing steel. A simplified approach neglecting the effect of strain induced transformation of austenite is attempted in the first phase. The depth at which the failure is expected to occur is compared with the experimental values of earlier investigation. The predicted values are marginally higher than the experimental values. � 2015 Elsevier B.V.