Ultimate seismic bearing capacities and failure mechanisms for strip footings placed adjacent to slopes

Abstract

Assessment of the ultimate bearing capacity of foundations adjacent to slopes is complex as it is highly dependent on the slope geometry and soil properties. Seismic loading may impact both the critical failure mechanism and its associated bearing capacity. The existing approaches for analyzing the seismic bearing capacity of footings near slopes typically employ coefficients developed to fit the conventions of Terzaghi’s bearing capacity equation, herein referred to as the “superposition method.” In this study, a rigorous assessment of the seismic bearing capacity is performed using an upper-bound limit state plasticity framework known as discontinuity layout optimization (DLO), which makes few prior assumptions concerning the failure geometry. Results show that soil properties, slope configuration, and pseudostatic seismic loading all influence the realized failure mechanism and associated bearing capacity. The use of bearing capacity coefficients that fit within the conventional superposition method may underestimate limit loads when the underlying soil provides a relative increase in resistance, but may greatly overestimate bearing capacity when the self-weight of the soil is destabilizing in nature. A set of design charts using direct computational methods for a variety of geometric, geotechnical, and seismic conditions is provided.

Seismic Bearing Capacity of Strip Footings on Cohesive Soil Slopes by Using Adaptive Finite Element Limit Analysis

“…e soil with unit weight c is assumed as a homogeneous media with undrained shear strength c u , following the Tresca yield criterion with an associated flow rule. Based on the pseudostatic approach, a same horizontal seismic acceleration coefficient k h is applied to the footing and the slope [17,36]. e vertical seismic acceleration coefficient is ignored owing to its insignificant influence on the seismic bearing capacity [36,37].…”

“…e stability problem of strip footing on slopes often occurs in engineering practice, which has been investigated by many researchers. To determine the bearing capacity of strip footing on slopes, different methods are used, ranging from semiempirical methods [1,2], limit equilibrium techniques [3][4][5][6], slip-line solutions [7,8], limit analysis [9][10][11], finite element methods [12,13], finite element limit analysis [14], and discontinuity layout optimization (DLO) approaches [15][16][17]. However, the effect of seismicity is not considered for all the studies mentioned previously, which should be treated carefully in earthquake areas due to the devastating influence of the footing under seismic conditions.…”

Influence of the Slope Shape on Seismic Stability of a Slope

“…e parameters affecting the geometry of the slope mainly include the slope height, slope angle, and slope shape [1]. Nowadays, research on these geometrical parameters of slope under seismic mainly focuses on the slope height, slope angle, and even the coupling between them [2,3]; however, for the slope shape, due to the complexity of the model construction, most studies have simplified it to linear shape, so the research is still limited in this field.…”

“…Düzgün and Budak [9] studied the differences in seismic responses between a single-faced slope and a ridge. Zhou et al [2] studied the influence of different seismic coefficients on the stability of convex slope under 3D conditions.…”

Application of a Non-Coaxial Soil Model with an Anisotropic Yield Criterion in Tunnelling

“…ese fundamental findings have been used to guide the development of realistic continuum soil models. In the past, analyzing the boundary value problems (e.g., bearing capacity of slopes, piles, and strip footings) normally assumed the stress and plastic strain rate to be coaxial [15][16][17][18], even for the seismic loads where severe principal stress rotations can observed [19,20]. Although a couple of authors [21][22][23][24][25] have applied their non-coaxial model in analyzing strip footing problems, these models have not widely been applied to analyze tunnelling problems, in particular, in the frame work of soil strength anisotropy.…”