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This paper investigates the performance of flexible culverts – often referred to as soil–steel composite bridges (SSCB) – when constructed in sloping topography. A number of 2D finite element models were created to simulate three case studies compromising two pipe arches and one high profile arch. The models were generated to investigate the effect of different surface slopes for different depths of soil cover. The aim was to understand and perceive the change of sectional forces in the structure with respect to slope increase under different soil covers. In addition, the effect of structure presence in the soil was also investigated in terms of soil stability. The results enable to realize the susceptibility of such structures to low heights of soil cover when built in sloping environment, which is seen in the incremental change in displacements and sectional forces, specially the bending moments. It is also found that the geometrical aspects of the profile shapes have more pronounced effect on their performance when introducing steeper slopes. The safety factor of soil stability is found to decrease when introducing such structures in the soil. [ABSTRACT FROM AUTHOR]

This paper provides an investigation of moisture migration patterns in the vicinity of mature trees and soil slope stability. A numerical model is presented for unsaturated moisture flow incorporating a sink term to represent water uptake by a tree. The resulting variation in soil moisture content (or suction) is then included within an extended slope stability analysis that employs a method of estimating shear strength as a function of suction in addition to net mean stress. The moisture transfer equation is solved via application of a finite element method. The resulting water uptake predictions have been validated previously and were shown to be in reasonable agreement with field measured data. The current work provides an assessment of the importance of this aspect of the problem on slope stability. Results show that seasonal soil suctions generated by a tree can influence the facture of safety against soil slope failure in the order of 8%. The research provides a further contribution to the overall assessment of slope stability. It may be included in routine calculations where maintenance of rail/road embankments may involve alteration (or removal) of vegetation. It may also be applied to vegetated natural slopes subject to deforestation or development. [ABSTRACT FROM AUTHOR]

This paper describes a procedure used to characterize the three-dimensional (3D) grain shape of lunar soil and undertake simulations of lunar soil by image-based discrete element method (DEM). Given that detailed 3D grain-shape information is unavailable for real lunar soil, a simulant material, FJS-1, is used in this study. We use the high-resolution micro X-ray CT system at SPring-8, a synchrotron radiation facility in Japan, to visualize precise 3D images of the granular assembly of FJS-1. A newly developed image-analysis procedure is then applied to identify individual grains. Using the obtained grain-shape data, a sufficient number of FJS-1 grains are directly modeled for DEM simulation using an efficient modeling scheme. A series of particle flow simulations are then performed with the modeled grains. The resulting slope angles are in good agreement with experimental results. We discuss the effect on the slope angle of grain parameters such as contact stiffness, restitution coefficient, and interparticle friction. [ABSTRACT FROM AUTHOR]