K.R. Saxena

Besides giving an historical introduction to embankment dams the book describes the need for instrumentation, planning procurement and installation practices of instruments. The significance of visual inspection and techniques, of monitoring various parameters, seepage, pore pressure, surface and internal displacements, earth pressures and seismic behaviour, through instrumentation has been described. Collection and processing of data and their use for back analysis to check stability of a dam at various stages of construction and reservoir filling have been suggested. In addition to case histories quoted in various chapters, an exclusive chapter on select case histories has been added which describes the conventional and latest instruments that are being used and methods adopted for installation, monitoring and analyses of data.

The increasing number of dams built in the last century has underlined the necessity of these constructions to the all-round development of a country. The advent of rock mechanics, engineering geology and a better understanding of materials have made it possible to construct higher and larger dams and to tackle more difficult sites. The assumptions and risks used in the theory of dam design include such unpredictable events as earthquakes, floods, and geological faults or soft seams, which may be either underestimated or completely missed during initial exploration. Incidents relating to dams are manageable at an early stage, whereas accidents, which are largely unforeseen, result in unexpected behaviour of dams and in catastrophic failures. Investigations conducted to determine the cause of a failure may not reveal the true sequence of events, while expert analyses are often controversial. From the dams that do not fail, of course, we learn nothing. Systematically monitoring the dam’s behaviour from the potential risk stage to the accident event, would allow a hazard-management programme to be implemented, minimising loss of life and property, and provide useful data.

The papers compiled in this book cover almost all aspects of in-situ characterization ranging from rock mass classification measurement of in-situ stresses, strength and deformation characteristics to field instrumentation and back analysis of observations made.

Linear mathematical assumptions for procedures in other branches of engineering have little relevance for geoengineering, which must accommodate non-linear behaviors. Contributors to eight papers apply the breakthrough numerical modeling Distinct Element Method (Cundall, late 1960s).