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In this paper, the physics of scour hole in a mixed sand-clay bed downstream of an apron is studied experimentally. Seven combinations of sand-clay mixtures including clay contents, Cc, ranging from 0 to 0.4 were used. The results show that Cc = 0.4 can reduce the maximum scour depth, εm, up to about 80% for all the densimetric Froude numbers in the range of the present study. An empirical equation has been proposed for calculation of εm in sand-clay mixtures with the mean error of 0.12. The removal mechanism of sediments from the bed was different based on the Cc. For low clay contents, i.e., Cc ≤ 15%, individual particles were detached from the bed. At higher Cc, clusters of particles were separated and moved downstream with the flow. A new equation has been proposed to predict the dimensionless scour hole profile in mixed sand-clay sediments. Dimensionless graphs have been presented for incorporating the effect of tailwater depth and sediment grain size on the main characteristics lengths in sand-clay mixtures. [ABSTRACT FROM AUTHOR]

This paper presents an analytical approach for predicting the length limits of integral bridges built on cohesive soils based on the flexural strength of the abutments and the low cycle fatigue performance of the steel H-piles at the abutments under cyclic thermal loading. First, H-piles that can accommodate large inelastic deformations are determined considering their local buckling instability. Then, a damage model is used to determine the maximum cyclic deformations that such piles can sustain. Next, nonlinear static pushover analyses of typical integral bridges subjected to cyclic thermal variations are conducted to study the effect of various geometric, structural, and geotechnical parameters on their performance. Equations are derived by using the analyses results to determine the maximum length limits of integral bridges built on cohesive soils. It is found that the maximum length limits of integral bridges is affected by the stiffness of the deck, height of the abutment, properties, and orientation of the piles as well as stiffness of the cohesive soils. [ABSTRACT FROM AUTHOR]