Soil structure interaction

About: Soil structure interaction is a research topic. Over the lifetime, 3653 publications have been published within this topic receiving 48890 citations.

Building frame-pile foundation-soil interactive analysis

Abstract: The effect of soil-structure interaction on a simple single storeyed and two bay space frame resting on a pile group embedded in the cohesive soil (clay) with flexible cap is examined in this paper. For this purpose, a more rational approach is resorted to using the three dimensional finite element analysis with realistic assumptions. The members of the superstructure and substructure are descretized using 20 node isoparametric continuum elements while the interface between the soil and pile is modeled using 16 node isoparametric interface elements. Owing to viability in terms of computational resources and memory requirement, the approach of uncoupled analysis is generally preferred to coupled analysis of the system. However, an interactive analysis of the system is presented in this paper where the building frame and pile foundation are considered as a single compatible unit. This study is focused on the interaction between the pile cap and underlying soil. In the parametric study conducted using the coupled analysis, the effect of pile spacing in a pile group and configuration of the pile group is evaluated on the response of superstructure. The responses of the superstructure considered include the displacement at top of the frame and moments in the superstructure columns. The effect of soil-structure interaction is found to be quite significant for the type of foundation used in the study. The percentage variation in the values of displacement obtained using the coupled and uncoupled analysis is found in the range of 4-17 and that for the moment in the range of 3-10. A reasonable agreement is observed in the results obtained using either approach.

Centrifuge modeling of seismic response of layered soft clay

Abstract: Centrifuge modeling is a valuable tool used to study the response of geotechnical structures to infrequent or extreme events such as earthquakes. A series of centrifuge model tests was conducted at 80g using an electro-hydraulic earthquake simulator mounted on the C-CORE geotechnical centrifuge to study the dynamic response of soft soils and seismic soil–structure interaction (SSI). The acceleration records at different locations within the soil bed and at its surface along with the settlement records at the surface were used to analyze the soft soil seismic response. In addition, the records of acceleration at the surface of a foundation model partially embedded in the soil were used to investigate the seismic SSI. Centrifuge data was used to evaluate the variation of shear modulus and damping ratio with shear strain amplitude and confining pressure, and to assess their effects on site response. Site response analysis using the measured shear wave velocity, estimated modulus reduction and damping ratio as input parameters produced good agreement with the measured site response. A spectral analysis of the results showed that the stiffness of the soil deposits had a significant effect on the characteristics of the input motions and the overall behavior of the structure. The peak surface acceleration measured in the centrifuge was significantly amplified, especially for low amplitude base acceleration. The amplification of the earthquake shaking as well as the frequency of the response spectra decreased with increasing earthquake intensity. The results clearly demonstrate that the layering system has to be considered, and not just the average shear wave velocity, when evaluating the local site effects.

Nonlinear soil‐structure interaction in plane frames

Abstract: Study of soil‐structure interaction effect in framed structures necessitates proper physical modelling of the structure, foundation and the soil mass. At the same time, the stress—strain model used for the constitutive relationship of the soil mass must also be realistic. In the present study, a hyperbolic stress—strain model has been used to consider the soil non‐linearity. The interactive behaviour of a five storey, two bay plane frame has been studied in detail and the results are compared with those obtained from a conventional and a linear interactive analysis.

Beam‐Column‐Analogy Model for Soil‐Structure Interaction Analysis

Abstract: A mathematical model for a combined soil subgrade plus structurallement in contact with the subgrade (e.g., a mat foundation) is presented. The structural portion of the model is a conventional flexural element. The subgrade portion of the model is Pasternak's hypothesis, which is fundamentally more accurate than the commonly used Winkler hypothesis. The novel element developed in this note is not the individual model components, but the fact that the combined model can be visualized as a spring‐supported beam‐column under constant axial tension. The column tension and springs represent the subgrade effects. This beam‐column analogy is useful in practice because it allows more accurate modeling of soil‐structure interaction within the capabilities of existing structural analysis computer software.

Earth Pressure Distribution on a Rigid Box Covered with U-Shaped Geofoam Wrap

Abstract: Earth loads acting on buried structures are known to be influenced by the characteristics of the soil, and the stiffness and geometry of the structure. To reduce earth pressure acting on buried structures, the induced trench installation technique has been recommended and applied in practice for several decades. It involves the installation of a soft zone immediately above the buried structure to mobilize shear strength in the backfill material. In this study an experimental investigation is conducted to measure the changes in contact pressure on the walls of a rigid structure buried in granular backfill with a U-shaped geofoam wrap. The results are compared with the conventional induced trench method as well as the positive projection installation with no geofoam. Contact pressures on the walls of the structure are measured using the tactile sensing technology. The experimental results are used to validate a finite element model that has been developed to analyze this soil–geosynthetic–structure interaction problem. The numerical model is then used to study the soil arching and the stresses developing in the backfill material for three different EPS densities. In addition, the role of geofoam density and the maximum fill height that can be carried safely without exceeding the design strain levels are examined. Conclusions are made regarding the effectiveness of this type of EPS inclusion on the earth pressure distribution around the buried structure.