Geotechnical problems often lead to an increase of construction time and costs for large highway and railway projects. Some reasons, which have led to failures and thus to a delay of construction works as well as to increasing costs, are demonstrated by means of case histories, in which the author was involved as expert or planner. Proposals are made how to identify the reasons and to avoid repetitions.
Bei Großprojekten der Verkehrsinfrastruktur stehen haufig geotechnische Aufgabenstellungen im Vordergrund. Wegen geotechnischer Probleme kam und kommt es haufig zu Termin- und Kostenueberschreitungen. Anhand einiger Beispiele, bei denen der Autor als Gutachter und Planer beteiligt war, wird gezeigt, welche Ursachen zu Schadensfallen und damit auch zu Termin- und Kostenueberschreitungen gefuehrt haben. Es werden Hinweise und Anregungen gegeben, wie die Ursachen erkannt und Wiederholungen von Schadensfallen vermieden werden können.
À grands projets de l'infrastructure de la circulation, souvent des taches geotechniques sont au premier plan. Par suite de problèmes geotechniques, souvent des dates et frais ont ete depasses. Au moyen de quelques exemples, à lesquels l'auteur participait comme expert et planificateur, les causes sont mises en vue qui menaient à des cas de dommage et par cela aussi à des depassements de dates et frais. Des indications et suggestions sont donnees pour s'apercevoir des causes et eviter des repetitions de cas de dommages.
The author has participated in many large-scale transportation infrastructure projects in Germany and abroad. Many of these projects are located in subdued mountain ranges. Rock mechanical and geological problems are therefore in the forefront.
In the following paper some examples are illustrated in which deadlines and budget limits were exceeded due to geotechnical questions. The purpose of this paper is to draw attention to this problem and to put the discussion on risk analysis and risk management on a broader basis. Incorrect assessments which have led to cases of damage and thus to deadlines and budget limits being exceeded have hurt the trust of the clients into our professional segment. It is therefore important in my opinion to identify the causes in order to avoid recurrence.
During excavation works for the construction of the bypass of the city of Herdecke, Germany, in the eighties, a slope failure occurred after strong rainfall (Fig. 1). About 300.000 m3 of rock slid on bedding planes of an alternating series of Devonian sand- and siltstones. The bedding planes were filled with mixed-grained soils. Apart from extensive damage to two residential buildings located on the slope, the sliding masses represented a threat to a Herdecke city district located at the slope toe, because a surcharge fill placed at short notice at the base of the slide did not lead to a stabilization of the slope . On the contrary, a further, deeper sliding surface was recognized shortly after the event, which could not be stabilized by the surcharge fill.
(Figure in full paper).
The bedding planes mentioned above dip at 18–20° in slope direction.