Assistant professor, Clarkson University, Potsdam, NY
Professor and vice provost, Georgia Institute of Technology, Atlanta, GA
The details of an automated flexible wall calibration chamber test system developed to perform strain-controlled model pressuremeter testing in cohesive soil are presented. The procedure involved in obtaining uniform speciments by consolidating a slurry of kaolin in two stages is described. The importance of automated control (electro-pneumatic control for this study) to perform second stage K0 consolidation accurately is shown. Typical test results are presented along with the evaluation of undrained strength, initial shear modulus, stress-strain variation, limit pressure, and horizontal stress using various methods of interpretation. Unload-reload loops were performed, and the shear modulus values were compared with the deduced values from the initial loading curve. Interpreting the pressuremeter test data using the Marquardt-Levenburg algorithm is presented. The improvements to the Simplex method are identified along with the effect of the reference state. A new procedure for incorporating the unloading portion in interpreting the pressuremeter test data is developed along with the detailed comparisons.
Paper ID: GTJ10421J