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Open Access Publications from the University of California

Finite Element Modeling of a Model-Scale, Rock-Socketed Pile Under Cyclic Lateral Loading

  • Author(s): Bajaj, Aditya Sunil
  • Advisor(s): Lemnitzer, Anne
  • et al.

Pile foundations are extensively used in the construction of various types of superstructures, including tall buildings, bridges, freeways and offshore structures. Hereby, rock-socketing offers an attractive solution for achieving maximal tip resistance and improving the load transfer capabilities of the foundation element. In soil profiles with very soft surface soils, rock-socketing often provides the only reliable source of axial and lateral resistance. This thesis investigates the nonlinear performance behavior of piles embedded in soil stratigraphies consisting of soft surface soil underlain by rock via experimental and numerical studies. Model scale test results of a (0.254m) 10in diameter pile, socketed in simulated rock, and subjected to quasi-static, reverse-cyclic lateral loading, provided reference performance data for a series of future experimental studies on large scale rock-socketed piles. Via numerical studies using the FEM tool Abaqus, this thesis complements the experimental research program, by first validating a previously conducted experiment published in literature and using the modeling experience gained from this preliminary exercise by seeking to replicate the test observation numerically. Results obtained from the model simulation provided pile response profiles that agreed reasonably well with experimental observations. Structural failure was observed through plastic hinging about two pile diameters below soil surface and captured well by the numerical model. The numerically obtained load deflection behavior over-predicts the experimental pile stiffness and indicated larger pile capacities compared to experimental observations. A discussion of the experimental results, numerical model development, modeling assumptions, modeling results including important pile demand parameters such as shear and moment demands, as well as recommendations for the upcoming large-scale tests are provided.

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