Abstract:
Dolomitic land is known for subsidence and sinkhole formation, making development such as
housing unsafe, especially when wad is found. Wad and residual dolomite are usually found
at the bedrock-soil interface and in grykes, in an unsaturated, non- to highly-reworked, state.
These are critical areas for ground stability of a dolomite site (Buttrick, 1986). This research
aims to better understand the geotechnical properties and hydrological behaviour of
unsaturated wad and residual dolomite in relation to the grading, fabric and geochemical
composition and the microstructure of the particles of the material, and how the reworking
processes alter these characteristic properties. The fabric of the residuum is inherent to the
structure of the parent rock, which is determined by the stress history of the rock. The fabric
influences the unsaturated behavioural characteristics and water holding capacity of the
material. The high and variable liquid limits is dependent on the overall fine grading, and the
nanoparticle structure and large reactive surfaces exhibited by the metal oxides in the
material. The residuum is typically non-dispersive, possess a low density, when not
reworked, that can be below that of water, mostly grades in the silt fraction and has hydraulic
conductivities in the order of 1x10-6 m/s. The mobilisation potential is dependent on the
presence of the fabric, variance of sorting of the material’s grain sizes and the disparity of the
degree of saturation above and below the wetting front moving through the material. The
material is considered reworked when mechanical processes destroy the structured or nonstructured
inherent fabric and foreign material is introduced into the soil matrix. The factors
influencing the consequential broad potential behavioural and characteristic properties of the
material are the type and degree of reworking and the environment of reworking.
