By M M H Al-Shaikh-Ali, Cheshire County Council, A G Davis, CEBTP, and M J Lloyd, Cheshire County Council
This paper was first published in GE’s January 1981 issue
This paper deals with the in situ measurement of the coefficient of effective earth pressure at rest in the Cheshire lodgement till, locally known as boulder clay, which consists principally of a firm to stiff, fissured sandy clay soil.
The method of measurement of the lateral effective earth pressure by hydraulic fracture in naturally sedimented clays has become common practice in many research programmes. First developed for clays by Bjerrum & Andersen (1972), several authors have reported lateral earth nressure orofiles measured in this way, e.g. Wilkes (1974), Massarch et al (1975), Tovenas et al (1975).
The importance of the determination of the coefficient of effective earth pressure at rest and hence the lateral effective earth pressure in foundation engineering has been emphasised for problems such as earth retaining structures and the prediction of settlements (Lambe, 1964 & 1967), progressive failure of clay slopes (Lo & Lee, 1973), the prediction of pore water pressure development in earth dam construction (Penman & Mitchell, 1970, and Pells, 1973) and the computation of lateral swelling pressures against friction piles in clay soils (Chandler, 1968, Kassif lk Baker, 1969, and Foley & Davis, 1971)