Engineers Australia

Hencky’s remarkable equation

Peter W. Mitchell

Abstract

Hencky’s Equation, used extensively in the theory of plasticity, is shown to provide the basis for the solution of many routine geotechnical problems, such as the bearing capacity of footings, the lateral resistance of piles and surcharge pressures on retaining walls. The original Hencky’s Equation applicable for weightless φ = 0 soils is extended to general c,φ soils, and is shown to accurately predict the results of hollow cylinder tests. The extended Hencky’s Equation enables the derivation of the bearing capacity of strip footings and piles in weightless c,φ soils. A case example is given showing that justification of high pile base bearing capacities in very stiff to hard clay was assisted by using derivations from Hencky’s Equation. The life of Hencky is summarised and it is shown that despite experiencing a degree of hardship, Hencky’s contribution was remarkable and provides an inspiration to present day geotechnical engineers.