Estimation of Modulus of Deformation of Ground from Axial Compression, Pull-out and Lateral Load Tests on Single Pile.-Paper

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The study estimates the ground’s modulus of deformation (Es) by back-analyzing full-scale pile load tests in compression, pull-out, and lateral loading. Using the initial linear portions of load–displacement curves and elastic-theory solutions, the authors account for pile installation and pile–soil interaction—effects that laboratory tests may not capture.<br /><br />Two case studies were examined. In China, compression and pull-out tests on bored piles produced markedly different estimates: approximately 70–77 MPa for compression and 3,187–4,764 MPa for pull-out. In Ontario, a trial-and-intersection procedure for a fixed-head lateral pile test yielded an estimated modulus of 123.91 MPa.<br /><br />The results show that ground deformation modulus is not a single, universal soil property. Its estimated value can vary substantially with loading direction and test type, as well as with ground conditions such as anisotropy and stratigraphic variation. The authors conclude that, despite practical difficulties, full-scale pile load tests provide a useful and satisfactory basis for estimating deformation modulus under relevant field conditions.

Keywords

ground deformation modulus

modulus of deformation

pile load tests

back analysis

load-displacement curves

elastic theory

pile-soil interaction

compression loading

pull-out loading

lateral loading