The Lateral Pressure and Resistance of Clay and the Supporting Power of Clay Foundations.

Layer-bound, low-displacement normal faults, arranged into a broadly polygonal pattern, are common in many sedimentary basins. Despite having constrained their gross geometry, we have a relatively poor understanding of the processes controlling the nucleation and growth (i.e., the kinematics) of polygonal fault systems. In this study we use high-resolution 3-D seismic reflection and borehole data from the northern North Sea to undertake a detailed kinematic analysis of faults forming part of a seismically well-imaged polygonal fault system hosted within the up to 1,000 m thick, Early Palaeocene-to-Middle Miocene mudstones of the Hordaland Group. Growth strata and displacement-depth profiles indicate faulting commenced during the Eocene to early Oligocene, with reactivation possibly occurring in the late Oligocene to middle Miocene. Mapping the position of displacement maxima on 137 polygonal faults suggests that the majority (64%) nucleated in the lower 500 m of the Hordaland Group. The uniform distribution of polygonal fault strikes in the area indicates that nucleation and growth were not driven by gravity or far-field tectonic extension as has previously been suggested. Instead, fault growth was likely facilitated by low coefficients of residual friction on existing slip surfaces, and probably involved significant layer-parallel contraction (strains of 0.01-0.19) of the host strata. To summarize, our kinematic analysis provides new insights into the spatial and temporal evolution of polygonal fault systems.

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“…For cohesive sediments, the horizontal stress would need to be reduced to ( Figure 13C; Bell, 1915):…”

Section: Fault Mechanicsmentioning

confidence: 99%

Kinematics of Polygonal Fault Systems: Observations from the Northern North Sea

et al. 2017

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“…Foundation designers address spread footing capacity primarily with a general bearing capacity equation initially formulated by Terzaghi (1943) for rigid square, circular, and strip foundations and based on work by Prandtl (1921) and Bell (1915). The equation has since been modified by various researchers to account for various correction factors to produce an equation of the form:…”

Section: Accepted Design Equation For Capacitymentioning

confidence: 99%

Accuracy, Uncertainty, and Reliability of the Bearing-Capacity Equation for Shallow Foundations on Saturated Clay

Strahler¹,

Stuedlein²

2014

Geo-Congress 2014 Technical Papers

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Shallow foundations derive their support from near surface soils and are extensively used to support structures of all sizes. Existing methods to estimate bearing capacity invoke an assumed failure surface developed within rigid-perfectly plastic soil, and require various semi-empirical modifications to the failure surface to account for geometrical effects. However, the global accuracy and uncertainty associated with the general bearing capacity equation and its modifications has not been sufficiently characterized with respect to observed full-scale footing load tests on plastic fine-grained soils. To assess the global accuracy and uncertainty in the general bearing capacity formula, a load test database consisting of 30 full-scale footings was developed from loading tests reported in the literature. The computed bearing capacity was compared to the capacity extrapolated from the load displacement curves in the database, then statistically characterized using the bias, or the ratio of the extrapolated and computed capacities. On average, the general bearing capacity formula under-predicted the extrapolated bearing capacity with a mean bias of 1.25 and exhibited a moderate to significant amount of variability (i.e., COV = 37%). In order to provide a reliability-based ultimate limit state model, varying levels of uncertainty associated with the undrained shear strength were used in the development of resistance factors for use with AASHTO load statistics. The use of risk-informed design approaches, such as those presented herein, should help to increase more efficient, and therefore sustainable, engineering practices.

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“…Location of the Rankine's failure plane in the embankment Bell (1915) developed an analytical solution to predict the contribution of cohesion to the lateral earth pressure. A tension zone of z o thickness from the surface exists, where the earth pressure is zero (Figure 3).…”

Section: The Safety Factor Against Overall Instabilitymentioning

confidence: 99%

Stability of highway embankments constructed on sloping ground against translational failure

Pantelidis

2008

Geomechanics and Geoengineering

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A translational failure of a highway embankment constructed on sloping ground may occur either in the mode of overall instability or in the mode of local instability. The stability analysis of the first mode is based on the assumption that the whole cross-section of the embankment will slide along the inclined base surface, whilst the second mode is based on the assumption of Rankine's active state of stress. In this paper the determination of the prevalent mode of failure --overall or local --is provided via a chart derived from force polygon analysis, with the dimensionless parameter, c¢/H, and the effective friction angle, '¢, as its axes. Furthermore, the determination of the most probable failure plane in the cross-section of the embankment is attempted and additionally the role of the cohesion in the stability is discussed. Finally, an estimation of the amplitude of failure at the road surface in the case of local instability is given. A confirmation of the aforementioned was achieved through case studies of highway embankments that have failed as a consequence of water infiltration and the development of high pore water pressures. A comparison between the local and the respective overall instability safety factor is given.

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The Lateral Pressure and Resistance of Clay and the Supporting Power of Clay Foundations.

Cited by 53 publications

References 0 publications

Kinematics of Polygonal Fault Systems: Observations from the Northern North Sea

Kinematics of Polygonal Fault Systems: Observations from the Northern North Sea

Accuracy, Uncertainty, and Reliability of the Bearing-Capacity Equation for Shallow Foundations on Saturated Clay

Stability of highway embankments constructed on sloping ground against translational failure

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