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A new permeability measurement method using a conventional self-boring pressuremeter (SBP) is described. The SBP self-bores to a predetermined depth. It is then retracted a short way, leaving a well-defined cavity in the ground. Water is pumped into the cavity at a constant rate, and the permeability is derived from the change in injection pressure with injection flow rate. A sequence of tests at a given horizon involves cavities of varying lengths, including a flush bottom or zero length cavity. In homogeneous materials the data from variable cavity lengths can be used to determine the anisotropy ratio. In heterogeneous materials the same data may allow the scale dependence to be evaluated if the anisotropy ratio can be independently obtained. Potential measurement errors are discussed in relation to smearing, temperature effects and leakage along the instrument. Results from Gault clay, London clay and Bothkennar clay are presented, with corroborating laboratory and other field test results where available. The preliminary assessment of scale dependence at these sites corresponds well to the degree of heterogeneity identified for the tested clays through visual observation.

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Geometric or shape factors are constants used in the interpretation of in-situ hydraulic conductivity tests, such as the Two-Stage Borehole (TSB) test in ASTM D6391-99. The finite boundary condition shape factors used with the TSB test are an extension of those derived by Hvorslev (1951) for infinite boundary conditions. The accuracy of this extrapolation is investigated here, using the finite element method (FEM) as a tool for deriving shape factors for finite boundary conditions. The utilized FEM has been validated against closed-form solutions for other test geometries. The resulting errors from the incorrect use of shape factors with the TSB test are discussed, and new shape factors derived from the FEM are presented in the form of a chart.