An analytical method for developing a theoretical load-settlement curve for axially loaded piles in clay is presented. The method is based on the correlation of the ratio of load transfer to soil shear strength as a function of pile movement. The results of studies of field tests of instrumented piles and laboratory tests of small piles in clay are used to obtain the desired correlation. The correlation is presented in the form of a family of curves that are obtained when the ratios of load transfer to soil shear strength versus pile movement are plotted as a function of depth. The validity of the family of correlation curves is checked by comparing computed and actual load-settlement curves for some typical field tests. Results obtained by this method indicate that the method may be used effectively to determine load-carrying capacity for axially loaded piles in clay.

Closure to “Load Transfer for Axially Loaded Piles in Clay”

The birth of smart materials such as piezoelectric (PZT) transducers has aided in revolutionizing the field of structural health monitoring (SHM) based on non-destructive testing (NDT) methods. While a relatively new NDT method known as the electromechanical (EMI) technique has been investigated for more than two decades, there are still various problems that must be solved before it is applied to real structures. The technique, which has a significant potential to contribute to the creation of one of the most effective SHM systems, involves the use of a single PZT for exciting and sensing of the host structure. In this paper, studies applied for the past decade related to the EMI technique have been reviewed to understand its trend. In addition, new concepts and ideas proposed by various authors are also surveyed, and the paper concludes with a discussion of the potential directions for future works.

A Review of the Piezoelectric Electromechanical Impedance Based Structural Health Monitoring Technique for Engineering Structures

The past several years have witnessed an increase in research on the nonlinear analysis of the structures made from reinforced concrete. Several mathematical models were created to analyze the beha...

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Simplified Damage Plasticity Model for Concrete

Geology Igneous Rocks Surface Processes Sedimentary Rocks Metamorphic Rocks Geological Structures Geological Maps Map Interpretation Tectonics Boundary Hazards Rocks of Britain Rocks of the US Weathering and Soils Floodplains and Alluvium Glacial Deposits Climatic Variants Coastal Processes Groundwater Ground Investigation Desk Study Ground Investigation Boreholes Geophysical Surveys Assessment of Difficult Ground Rock Strength Rock Mass Strength Soil Strength Ground Subsidence Subsidence on Clays Subsidence on Limestone Subsidence Over Old Mines Mining Subsidence Slope Failure and Landslides Water in Landslides Soil Failures and Flowslides Landslide Hazards Slope Stabilization Ground Conditions Rock Excavation Tunnels in Rock Stone and Aggregate Appendices Rock Mass Quality Q System Abbreviations and Notation Further Reading Index

Foundations of engineering geology

Energy and geotechnical behaviour of energy piles for different design solutions

Sand dilates with shearing at a rate that increases with increasing relative density DR and decreases with increasing effective confining stress c. The peak friction angle of a sand depends on its critical-state friction angle and on dilatancy. In this paper, we develop a simple correlation between peak friction angle, critical-state friction angle, and dilatancy based on triaxial compression and plane-strain compression test data for sand for a range of confining pressures from very low levels to approximately 196 kPa. DOI: 10.1061/ASCEGT.1943-5606.0000237 CE Database subject headings: Sand, Soil type; Stress; Dilatancy; Shear strength; Friction. Author keywords: Sand; Low confining stress; Dilatancy; Shear strength; Friction angle.

Dilatancy and Shear Strength of Sand at Low Confining Pressures

Geothermal energy piles in sand subjected to cyclic thermal loading with fifty thermal cycles and constant mechanical axial load are analyzed numerically in the present work using the nonlinear transient finite element analysis method. The resulting soil–structure interaction is investigated through these analyses. The stress–strain response of sand is simulated herein using the Mohr–Coulomb constitutive model. Mechanical behavior of energy piles is simulated using the concrete damage plasticity model. Analyses are carried out for floating and end bearing piles in both loose and dense sands subjected to different constant axial load magnitudes at the pile head. Parametric sensitivity studies are performed for different amounts of temperature variation on the pile. It is observed from the results that the mechanical load governs the response of the piles when the piles are subjected to higher mechanical loads close to the limit load value on the pile. However, at low to moderate axial load magnitudes, thermal expansion of the pile causes uplift of the piles. Due to pile uplift, negative shear forces are generated at the pile–soil interface near pile head. The radial strains induced in the pile due to thermo-mechanical loading are observed to be higher than that induced due to only mechanical loading. The axial stress in the piles also increases when pile is subjected to heating.

Cyclic Thermo-Mechanical Analysis of Energy Piles in Sand

Installation of a displacement pile often involves complex loading modes that cause substantial changes in the state of the soil surrounding the pile. When a displacement pile is installed in saturated clay, significant excess pore pressure develops. As the excess pore pressure dissipates over time, the effective stresses in the soil surrounding the pile and the pile capacity increase. This paper investigates jacking of piles into clay using finite-element analysis. A two-surface plasticity-based constitutive model for clays was implemented in the finite-element code Solid Nonlinear Analysis Code. Based on the numerical results, equations are developed for quantifying the effects of undrained and residual shear strength on the shaft resistance of jacked piles in clay. The gain in shaft resistance over time is assessed and setup factors are proposed that can be used to estimate the gain in shaft resistance as a function of time after installation of a jacked pile in clay. Good agreement was obtaine...

Tanusree Chakraborty

Papers

Dilatancy and Shear Strength of Sand at Low Confining Pressures

Cyclic Thermo-Mechanical Analysis of Energy Piles in Sand

Shaft Resistance and Setup Factors for Piles Jacked in Clay

Investigations on effectiveness of embedded PZT patches at varying orientations for monitoring concrete hydration using EMI technique

Characterization of three Himalayan rocks using a split Hopkinson pressure bar