M. Yao

M.Sc. Thesis, Wolfson College, Oxford University, Hilary Term 1996

A Study of the Effect of Length to Diameter Ratio on the Results of Pressuremeter Tests

Summary

The pressuremeter is one of the most commonly used devices in in-situ testing, because the interpretation method is relatively easy on the assumption that the pressuremeter is infinitely long. However, the effects of lenght-to-diameter ratio on test results have been questioned recently, and so this thesis explores the effects of length-to-diameter ratio on the results of pressuremeter tests in soils.

First, the finite element method is used to analyse numerically the effects of length-to-diameter ratio on self-boring pressuremeter test results, both in sand and in clay since it is impossible to solve the cavity expansion problem theoretically on the assumption that the length of the pressuremeter is finite. In the analysis of clay, the effects of length-to-diameter ratio on the shear modulus and the shear strength are emphasized. In the analysis of sand, the effects of the length-to-diameter ratio on friction angle are emphasized.

The finite element method is also used to analyse the effects of length to diameter ratio on full-displacement pressuremeter test in clay. The effects of lenght-to-diameter ratio on the rigidityindex, shear strength, shear modulus and initial horizontal stress are emphasized.

Finally, several calibration tests are performed to investigate the effects of length-to-diameter ratio on the limit press of a full-displacement pressuremeter in sand. Three values of length-to-diameter ratio (5, 10 or 20) are used to investigate the effects.

Thesis (4.48MB, pdf)

This thesis can also be downloaded from the ORA website