ABSTRACT
Empingham dam is one of the last large dams to be built on a stiff plastic clay in the UK, using a fill derived from the same clay (Bridle et al. 1985). It is a zoned earth-fill dam 37m high and 1200m long, founded on Upper Lias Clay (ULC) (Figure 1). The ULC in the valley slopes was extensively disturbed by cambering and in the valley floor by bulging (Horswill & Horton, 1976). The clay was then brecciated by periglacial ground freezing. Brecciated clays have severely disturbed fabric which is heterogeneous and therefore causes variation in the undrained shear strength. Hence, at the design stage there were uncertainties with respect to the properties of the ULC (and the fill derived from it).
