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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.

To assess the long-term integrity, and hence adequate performance, of landfill lining systems the designer must consider interaction between lining components and the waste body. Information on typical ranges of waste mechanical properties is required for use in numerical modelling of this interaction. This paper presents results from a programme of pressuremeter testing in municipal solid waste (MSW) carried out to measure shear stiffness properties. An optimum procedure has been developed using a high-pressure dilatometer in a preformed test pocket. Tests have been conducted in fresh and partially degraded MSW deposits. Values of shear moduli for small to intermediate strains have been obtained from series of unload–reload loops, and these show a strong relationship between shear modulus and depth. Stiffness increases with cavity strain owing to drained cavity expansion. A clear linear relationship has been found between shear stiffness and stress level. Results for fresh MSW from two landfill sites show close agreement. Good agreement has been found between shear stiffness values calculated for small strain in pressuremeter tests and shear stiffness values measured using the continuous surface wave method. They also compare well with the limited amount of information in the literature.

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