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The stability of slopes is typically evaluated by two-dimensional plane strain analysis. However, many slopes exhibit three-dimensional (3D) geometries, including slope corners. Several researchers have studied the stability of slope corners but found that the factor of safety (FS) was close to the FS for the plane strain case. The results of a new series of 3D finite element method (FEM) simulating slope corners, including slope angle, plan view angle, radius of curvature, and slope height are presented. They confirm that the FS does not vary much for corners compared to the plane strain case. However, 220 cases using an elastic-perfectly plastic soil model together with the FEM shear strength reduction method show that the displacement field is very different at the corners compared to plane strain with differences reaching over 100%. The displacement ratio between corners and plane strain is presented as a function of the plan view angle of the corner. Often failure is defined at a chosen large displacement, as in the ultimate load of foundation elements. If this concept is carried over to slope stability, it would indicate that the FS of corners should be very different from the plane strain case. A possible explanation is discussed. [ABSTRACT FROM AUTHOR]

The problem of the bump at the transition between the embankment and the bridge is an important concern for railways and highways. These bumps can lead to a rough riding surface which creates discomfort at high speed and high maintenance costs. The current study addresses the problem for High Speed Trains (HST). One reason for the development of a bump is the difference in stiffness between the compacted soil embankment and the bridge typically resting on deep foundations. A 4-D finite element model, developed in LS-DYNA, was used to simulate the effect of this difference in stiffness at the transition between the embankment and the bridge. The modulus of the embankment is varied from 5 MPa for a very soft embankment to 120 MPa for a very stiff embankment. The bridge is considered to be rigid by comparison. This study will show that the dynamic amplification factor, DAF, defined as the ratio of the maximum dynamic rail/wheel impact force to the static load on the wheel, changes dramatically with the embankment modulus and train speeds. [ABSTRACT FROM AUTHOR]

Groups of in-line piles connected by beams are being used to contain errant vehicles for roadside safety and perimeter protection of sensitive infrastructure. The effectiveness of in-line groups of piles to safely redirect or stop approaching vehicles has not been well investigated from the geotechnical point of view. In this paper, the performance of barriers is examined through full-scale crash tests and numerical simulations. The full-scale crash tests consisted of two different configurations of piles and beams as well as two different soil types: one was in loose sand and the other in hard clay. Both barriers were subjected to vehicle impact: one by a medium-duty truck and the other by a pickup truck. The barriers successfully contained the impacting vehicles. Detailed finite-element models of the barriers and the soil were developed and combined with the vehicle models to simulate the dynamic events. Comparison between predicted and measured behavior was used to calibrate the models. Additional simulations were performed to evaluate the effect of major structural and geotechnical design parameters including soil strength, pile spacing, and number of piles on the impact response of these systems. Practical recommendations are drawn from the experimental and numerical work. [ABSTRACT FROM AUTHOR]

Utilizes a three-dimensional nonlinear finite-element analysis to study the influence of various design decisions for tieback walls. Literature on tieback walls; Study of boundary effect using a linear elastic soil; Description of soil and structure element model; Simulation of excavation sequence.