Finite element modeling of Florida soil with the PENCEL Pressuremeter

For many years, numerical codes that use the Finite Element Method were restricted to research. Advances in computing power have now enabled these codes to move out of the laboratory and into the hands of geotechnical engineers. Behavior of soil is implemented in these codes by way of constitutive models. These models were typically derived based on theoretical soil mechanics or fitted empirically to a soil test with known boundary conditions. In order to fit these models to a specific soil in question, a set of soil parameters must be passed into the code.; In the simplest case, a linear elastic model could be used where the only parameters needed are modulus and Poisson's ratio. In many cases, such a simple representation is not sufficient. Instead of a constant stiffness, the stiffness may change with changes in stress. Strains may include elastic and plastic contributions. Failure or yield surfaces may be implemented to describe soil strength, and other limits.; The purpose of this study was to take a critical look at the PENCEL Pressuremeter as a means for developing finite element constitutive model input parameters. The first part of the research looked at eight PENCEL Pressuremeter tests performed where natural sands were sampled for laboratory testing. Triaxial tests on these sands were used to develop baseline input parameters. These parameters were verified by simulating the triaxial tests using two finite element codes.; An examination of the PENCEL Pressuremeter field curves yielded no correlation with the triaxial parameters. An attempt was then made to “signal match” the triaxial input parameters to match the pressuremeter test. This best match yielded a factor Ω by which the triaxial stiffness is multiplied to match the pressuremeter test, where Ω is a function of the PENCEL limit pressure.; These findings were used to predict the deformations of a cantilevered sheet pile wall. PENCEL Pressuremeter tests were conducted before the wall was installed. Deflections of the wall were measured during excavation. Soil parameters derived from the PENCEL Pressuremeter and the cone penetration test were used in the finite element code to determine the deflections of the wall with depth.