Luiza Dihoru

Model Container Design for Soil-Structure Interaction Studies

Physical modelling of scaled models is an established method for understanding failure mechanisms and verifying design hypothesis in earthquake geotechnical engineering practice. One of the requirements of physical modelling for these classes of problems is the replication of semi-infinite extent of the ground in a finite dimension model soil container. This chapter is aimed at summarizing the requirements for a model container for carrying out seismic soil-structure interactions (SSI) at 1-g (shaking table) and N-g (geotechnical centrifuge at N times earth’s gravity). A literature review has identified six types of soil container which are summarised and critically reviewed herein. The specialised modelling techniques entailed by the application of these containers are also discussed.

Experimental Investigation of Dynamic Behavior of Cantilever Retaining Walls

The dynamic behaviour of cantilever retaining walls under earthquake action is explored by means of 1-g shaking table testing, carried out on scaled models at the Bristol Laboratory for Advanced Dynamics Engineering (BLADE), University of Bristol, UK. The experimental program encompasses different combinations of retaining wall geometries, soil configurations and input ground motions. The response analysis of the systems at hand aimed at shedding light onto the salient features of the problem, such as: (1) the magnitude of the soil thrust and its point of application; (2) the relative sliding as opposed to rocking of the wall base and the corresponding failure mode; (3) the importance/interplay between soil stiffness, wall dimensions, and excitation characteristics, as affecting the above. The results of the experimental investigations were in good agreement with the theoretical models used for the analysis and are expected to be useful for the better understanding and the optimization of earthquake design of this particular type of retaining structure.

Dynamic Behaviour of Reinforced Soils – Theoretical Modelling and Shaking Table Experiments

The dynamic response of soil-pile-group systems are modelled both analytically, using homogenisation theory, and physically, using a shaking table to excite a soft elastic material periodically reinforced by vertical slender inclusions. A large soil/pile stiffness contrast is shown to lead to full coupling in the transverse direction of the bending behaviour from the piles and the shear behaviour from the soil. Analytically derived performance predictions capture important characteristics of the experimentally observed response that are missed when using alternative analytical modelling approaches. The homogenisation theory approach to modelling of generalised media is valid.

Experimental Assessment of Seismic Pile-Soil Interaction

Physical modeling has long been established as a powerful tool for studying seismic pile-soil-superstructure interaction. This chapter presents a series of 1-g shaking table tests aiming at clarifying fundamental aspects of kinematic and inertial interaction effects on pile-supported systems. Pile models in layered sand deposits were built in the laboratory and subjected to a wide set of earthquake motions. The piles were densely instrumented with accelerometers and strain gauges; therefore, earthquake response, including bending strains along their length, could be measured directly. Certain broad conclusions on kinematic and inertial SSI effects on this type of systems are drawn.

Shaking Table Experimental Programme

The graphite components in AGR cores are subject to degradation processes that are predicted to lead to greater numbers of weakened and cracked components. The reactor core models used to assess the tolerability of the cores to seismic events need to represent higher levels of degradation. A shaking table programme has commenced, with the primary goal to provide experimental validation of the existing AGR core models. This paper presents the proposed rig work with main aspects of physical model design, rig manufacturing and dynamic testing being addressed. The candidate instrumentation systems and the relevant rig outputs are also described.

EXPERIMENTAL INVESTIGATION OF DYNAMIC BEHAVIOUR OF CANTILEVER RETAINING WALLS

The dynamic behaviour of cantilever retaining walls under earthquake action is explored by means of 1-g shaking table testing, carried out on scaled models at the Bristol Laboratory for Advanced Dynamics Engineering (BLADE), University of Bristol, UK. The experimental program encompasses different combinations of retaining wall geometries, soil configurations and input ground motions. The response analysis of the systems at hand aimed at shedding light onto the salient features of the problem, such as: (1) the magnitude of the soil thrust and its point of application; (2) the relative sliding as opposed to rocking of the wal land the corresponding failure mode; (3) the importance/interplay between soil stiffness, wall dimensions, and excitation characteristics, as affecting the above. The results of the experimental investigations are in good agreement with the theoretical models used for the analysis and are expected to be useful for the better understanding and the optimization of earthquake design of this type of retaining structure.

Performance Requirements of Actuation Systems for Dynamic Testing in the European Earthquake Engineering Laboratories

A review of the current actuation technology in the European laboratories of earthquake engineering is presented. The existing laboratory infrastructures, the current types of dynamic tests and actuation requirements are investigated. The needs of the earthquake engineering community that are not met by the currently available actuation devices are explored. User opinions are investigated in relation to the desirable performance enhancements and potential optimization solutions for hydraulic, electrical and hybrid actuation devices that would expand the experimental capabilities for dynamic testing. Various avenues for improving the current actuation capabilities are explored and several technical solutions are proposed. The future direction of actuation technology is discussed.