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To arrest rockfall boulders, baffles are constructed as steel members affixed on top of a concrete footing. Existing designs aim to prevent any footing rotation and steel member bending. As such, existing baffle designs require massive reinforced concrete footings and complex bolt and weld connections. Such designs have limited constructability and result in complex failure mechanisms (i.e., tensile failure of concrete foundation at connections). In this paper, we introduce a new baffle design concept that optimizes the balance between steel member bending and footing rotation to enable a compact design. Full-scale pendulum experiments are conducted to evaluate the proposed easy-to-construct and design baffle under successive boulder impacts of 50 kJ. It is demonstrated that by considering the effects of steel member deflection and concrete foundation rotation, the maximum impact force on baffles is reduced by up to two times when compared with those on a rigid barrier and the failure modes are simplified to either overturning failure of the footing or buckling failure of the steel member. A ratio that defines the flexural capacity of the steel member to the overturning capacity of the shallow concrete foundation is proposed to control the failure mode. The optimized baffle configuration for an impact energy of 50 kJ, with minimum residual deflection, has a target capacity ratio of 2.0. • A capacity ratio (flexural capacity of steel member to overturning capacity of footing) is proposed for baffle design. • A new baffle design concept is proposed and evaluated using full-scale pendulum experiments. • A failure criterion based on baffle rotation is proposed considering the residual boulder velocity. [ABSTRACT FROM AUTHOR]

Spudcans are typical foundations used in shallow to moderate-depth water oil and gas fields to support jack-up drilling units. Understanding the behaviour of spudcans under combined loadings is crucial to the overall response of the jack-up structure. This paper presents the development of a strain-hardening plasticity model for a spudcan footing on loose sand. Most of the model components are developed from direct centrifuge observations. The centrifuge tests were performed at an acceleration of 100 times that of the Earth's gravity on a model spudcan footing subjected to combined vertical, horizontal, and moment loads. All the experiments have been designed and conducted to allow the results to be interpreted with a strain-hardening plasticity framework. Combined loads were applied by using a novel apparatus, which enables independent vertical, horizontal, and rotational movements of the footing. Test results also revealed the existence of a three dimensional sliding surface that intersects with the conventional yield surface. This additional surface has been defined analytically. Retrospective simulation of the experimental data using the plasticity model confirms the model's capability for use in predicting the behaviour of larger spudcan applications offshore. [ABSTRACT FROM AUTHOR]

Foundations resting adjacent to the crest of a slope exhibit a smaller bearing capacity respect to the case of horizontal ground. In this paper the static and seismic values of the bearing capacity factor N γg for shallow strip foundations adjacent to slopes were evaluated using the method of characteristics, extended to the seismic case by means of the pseudo-static approach. N γg was evaluated for different values of the slope angle and, under seismic conditions, accounting only for the effect of horizontal and vertical inertia forces arising in the foundation soil. The results, for both smooth and rough foundations, are presented and checked against those obtained through finite element analyses. [ABSTRACT FROM AUTHOR]

The bearing capacity factor ( N γ ), correction factor ( K γ ), and failure mechanism of a strip footing with a rigid basement were investigated using UBFEM-RTME. The footing–sand interface and the sand-basement interface were assumed perfectly rough. The results are presented in terms of the variations of N γ and K γ with the friction angle, ϕ , and dimensionless thickness, h / b , of the sand. When h / b is smaller than dimensionless critical depth H cr / b , N γ and K γ increase with decreasing h / b or increasing ϕ and the mesh-like failure mechanism is found to confine within a small domain. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on the dynamic interaction effect of closely spaced square foundations under machine vibration. Under a dynamic condition, a number of large-scale model tests were conducted in the field, which includes a wide range of study on the isolated as well as interacting footing response resting on the local soil available at Kanpur, India. The dynamic interaction of different combinations (size) of two-footing assemblies was investigated by inducing vertical harmonic load on one of the footings (active footing), while the other footing (passive footing) was loaded with static weight only. The active footing was excited with different magnitudes of dynamic loading and the response was recorded for both footings, placed at a different clear spacing ( S). The results are compiled and shown as the variation of displacement amplitude with frequency. The transmission ratio that predicts the effect of dynamic excitation of the active footing on the passive one is determined for the interacting footings and plotted with respect to frequency ratio. [ABSTRACT FROM AUTHOR]

Two geotechnical centrifuge tests were designed to elicit the influence of soil-foundation-structure interaction (SFSI) and structure-soil-structure interaction (SSSI) effects on the seismic demands of an inelastic frame structure founded on individual spread footings. Four experimental cases were considered: (1) SFSI of an individual inelastic frame structure (baseline case); (2) in-plane SSSI between the frame structure and a large elastic wall structure designed to respond predominately in a rocking mode; (3) anti-plane SSSI between the frame and wall structures; and (4) combined in-plane and anti-plane SSSI between the frame structure and two wall structures. Results from Cases 1, 2, and 4 are analyzed considering 13 demand parameters. The peak seismic demands from the baseline case are compared to the peak demands from the SSSI cases to elicit the impacts of building adjacency. The number of earthquake motions that resulted in increases or decreases in the seismic demands in the frame structure are tracked for the SSSI cases. For these tests, SSSI consistently results in increased peak foundation moment and foundation base shear demands, regardless of the geometric layout of the structures. These increases propagate throughout the superstructure, resulting in increases in moment, shear and curvature ductility demands in the structural components. SSSI effects are observed to be most significant for low-to-moderate intensity earthquake motions, suggesting that particular consideration should be given to the likelihood of SSSI for highly probable earthquakes. [ABSTRACT FROM AUTHOR]

Conventional bearing capacity analyses for shallow foundations placed on slopes use a modified set of bearing capacity factors based on soil properties, footing geometry, and slope configuration, but are restricted to purely cohesionless or purely cohesive soils. This approach is adequate for establishing bearing capacity on engineered fills with controlled foundation properties, yet does not adequately address design for bearing capacity on soils that have both cohesion and internal frictional resistance--a common scenario for native soils. This role becomes increasingly important in design for mechanically stabilized earth walls, which are often placed on slopes of native c'-φ' soils in which the bearing capacity can often be the critical design constraint. Prior approaches to bearing capacity on horizontal ground for c'-φ' soils utilize principles of limited state plasticity in their formulation, yet the most commonly applied bearing capacity approaches on slopes use semiempirical formulations that employ mutually exclusive soil strength parameters. In this work, results are attained using upper-bound limit state plasticity failure discretization scheme, known as discontinuity layout optimization (DLO), which uses nonassumptive failure geometry (under translational kinematics) in its formulation. The values presented demonstrate important components in consideration of bearing capacity for strip footings placed adjacent to slopes of c'-φ' soils, in particular, the relationship between soil strength properties, slope height to footing width ratio, slope angle, and critical collapse mechanism. A set of reduction coefficients that can be directly applied to the classical bearing capacity formulation is presented for ease of application. [ABSTRACT FROM AUTHOR]

A fully instrumented experiment was conducted to investigate the soil-structure interaction of single short, stiff laterally loaded piles. A hollow steel pipe pile with a diameter of 102 mm, a thickness of 6.4 mm, and a length of 1.524 m was installed in well-graded sand and subjected to increasing lateral load. The pile and surrounding soil were fully instrumented using advanced sensors, including flexible shape acceleration arrays, thin tactile pressure sheets, and in-soil null pressure sensors. The sensors attached to the pile were used to develop the compressive soil-pile interaction pressures and the lateral displacement along the pile length. The tactile pressure sheet sensors provided the soil-pile interaction compressive pressures on the circumference of the pile at a specific depth and along the length of the pile. The measured soil-pile interaction compressive pressures combined with the measured lateral displacement along the pile length were used to develop the soil-pile interaction force-displacement relationships ( curves) using direct measurements. In addition, the in-soil null pressure sensor measurements were used to develop the distribution of horizontal stress changes around the pile as the lateral pile displacement increased. When appropriate, the measured results were compared with data and methods available in the literature. [ABSTRACT FROM AUTHOR]