Testing ground characteristics using expansive pressure probe with augmented vertical stress is accompanied by circulating water through the ground, between injection and pumping cells

摘要

External water circulation is caused in the ground, between injection- and pumping cells. An Independent claim is included for the corresponding equipment, comprising a central pressure expansion and measurement cell (6), with, on either side: a cell injecting water (7) into the ground, and a pumping cell (8) permitting water intake by the hydraulic circuit. Guard cells are used to promote uniform stress, and to prevent water rising back up the borehole. Preferred Features: Measurement of pressures and flowrates at injection and pumping cells, provides a measure of ground permeability. The coefficient of consolidation is measured, using the coefficient of permeability and the modulus of elasticity, taken from the charge-discharge cycle of the apparatus expansion curve. The ground angle of internal friction is determined for a value of c.cotg phi , using values of the slope of the straight line joining logarithms of the corrected pressure increased by the term c.cotg phi , and of deformation corrected for pressures exceeding the flow pressure. Solutions between angle of friction and c.cotg phi for two different close tests, with the different simulated vertical stresses, give a unique intersection and a unique solution in terms of cohesion and angle of internal friction.