Significance of discontinuity surveying in motorway alignment selection, southern Turkey

A detailed discontinuity survey is an essential part of a route location study, because rock quality and subsurface geological conditions can be determined by examining discontinuity systems. It also helps to prepare a sound subsurface investigation programme in the later stages of an engineering project. f the more expensive structural elements of a motorway are tunnels, viaducts, reinforced retaining walls and contiguous piles. Each has special requirements depending on ground stability, cost and environmental aspects. A detailed discontinuity survey enables engineers to select the best route and to optimize the geotechnical design. study from the Tarsus-Adana-Gaziantep (TAG) motorway being constructed in southern Turkey displays well the role of a discontinuity survey in engineering geological and geotechnical work. The survey, which was carried out by visual inspection and practical field tests, indicated, on the basis of the consistency of the discontinuity systems in each rock exposure, that the suspected floating blocks were outcrops of in situ rock. Misinterpretation of the actual ground condition caused loss of both time and money.