UBC Theses and Dissertations
An evaluation of the full displacement pressuremeter O’Neill, Bruce Ernest
The self-boring pressuremeter which is inserted into the ground without disturbing the surrounding soil has two drawbacks. Skilled operators are needed to insert the probe into the ground without disturbing the soil, and the self-boring process requires a jetting action or a rotating cutter and drilling mud. One method of simplifying the pressuremeter installation procedure is to install the probe in a full displacement manner. A solid tip is placed oh the end of the probe and then the pressuremeter is pushed into the ground in the same manner as a cone penetrometer. This research project was performed to examine the suitability of using the full displacement pressuremeter for determining shear modulus, insitu horizontal stresses, and undrained shear strength. The variables examined were; the type of pressuremeter, whether the pressuremeter was run in a stress or a strain controlled manner, the size of the tip pushed in front of the pressuremeter, and whether time was allowed for the dynamic pore pressures to dissipate. Tests were conducted in sand, silt, and clay. When the shear moduli measured with the full displacement pressuremeter were adjusted to account for the differences in strain level, and mean effective stress they compared very well with the dynamic shear moduli measured with the seismic cone. The attempts to determine the insitu horizontal stress by examining the liftoff pressure were unsuccessful. The undrained shear strengths of clay determined using cavity expansion theory compared very well with undrained shear strengths determined using the field vane.
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