Self‐Boring Pressuremeter Tests In Soft Clay

Abstract

The basic objective of a self‐boring pressuremeter (SBPM) test is to insert a cylindrical probe into the ground with a minimum of disturbance and expand the membrane covering the probe so as to load the soil to failure. The test data from the expansion phase allows the determination of lateral earth pressure, shear strength, stress‐strain behavior, and, in some cases, coefficient of consolidation. In spite of its considerable potential, as more investigators have utilized the SBPM, inconsistencies have been reported in the test results. To help resolve some of the uncertainties, 32 SBPM tests were conducted in soft San Francisco Bay Mud wherein key parameters were varied one at a time to isolate their influence. The parameters considered included: expansion rate, cutter position, cutting rate, and cutting shoe dimension. Furthermore, a microcomputer data acquisition system and loading technique were developed that allowed the test to be carried out automatically while recording a high density of data. The results of this study indicate that disturbance is the factor that has the greatest influence on the interpreted results from the SBPM test.