Pore water pressure build-up and dissipation is one of the most important soil behaviour characteristics that influences the deformation of geotechnical structures. In environmental geotechnics, permeability frequently dominates the transport of contaminants through the ground as well as the effectiveness of remediation and containment efforts. It is generally desirable to test a representative volume of soil to obtain a reliable estimate of permeability. In situ testing has this advantage and becomes more attractive with the self boring method where the structure of the soil is preserved. A novel procedure for measuring the vertical and lateral permeability of cohesive soils is presented. The technique utilizes the standard self boring expansion pressuremeter of the Cambridge design with some minor attachments. While there are other self boring instruments that were purpose built for measuring permeability, it is obviously desirable to obtain a direct measurement of the coefficient of permeability as one of a number of fundamental soil properties from a single self boring test. An outline of the proposed method is presented together with preliminary test data from a stiff clay deposit in the U.K. (Gault Clay).
There are various methods in place today for measuring permeability in situ. These include tests in driven or pushed-in-place piezometers, packer type tests and tests in standpipe piezometers placed in pre-drilled boreholes.
Following the development of self boring pressuremeters, various instruments taking advantage of the self boring technique were developed, including self boring permeameters (Baguelin et al., 1974; Capelle, 1983; Harwood et al., 1995). This arises due to the choice of location of the test area on the instrument. It is observed that the injection zone utilizes the same general area on the body of the instrument that is usually occupied by the expansion pressuremeter membrane.
