Zur Statik der Bodenbewehrung

A contribution to the statical analysis of soil reinforcement. Two approaches for the design of nailed cuts are presented in this work. The first approach is based on the comparison between the dissipation of the soil‐nail system at limit state and the work of the external forces. The second approach is based on a homogenisation of the soil‐nail system. By using the theory of mixtures, the required percentage of reinforcement can be calculated. The proposed methods are elucidated with calculation examples.     

Effect of rare earth cerium on the impact toughness,corrosion and wear resistance of CrNiMnMo alloyed lining steel

The effects of the addition of rare earth cerium on the impact corrosion and wear resistance of CrNiMnMo alloyed lining steel were studied using metallurgical microscopy, scanning electron microscope, x-ray powder diffraction, a hardness tester, an impact tester, and an impact corrosion abrasion tester. The properties of CrNiMnMo alloyed lining steel with the addition of cerium were compared with that of CrNiMnMo steel without the addition of cerium after being heat treated by same processes. The results show that CrNiMnMo alloyed lining steel with the addition of rare earth cerium consisted of lath martensite with a low residual austenite phase after being quenched and tempered. The lath of the martensite was fine and uniform. The impact toughness and the corrosion resistance of the steel lining board improved greatly with the addition of cerium and the impact toughness increased by 22 % with the fracture mode of being ductile. The CrNiMnMo alloyed lining steel with cerium showed the highest resistance to impact corrosion abrasion compared with the alloy without cerium.     

Langjährige Erfahrungen des Tragverhaltens von Bewehrte‐Erde‐Brückenwiderlagern

Das Bauverfahren „Bewehrte Erde“ wurde nach der Einführung in den frühen 60‐er Jahren des letzten Jahrhunderts zum Bau von zahlreichen Stützwänden und Brückenwiderlagern angewandt. Der Beginn der Erforschung des Tragverhaltens von Bewehrte‐Erde‐Brückenwiderlagern liegt mehr als 40 Jahre zurück. Seitdem sind durch Modellversuche, Messungen an Test‐ und reellen Bauwerken zahlreiche Verbesserungen und Optimierungen am entwickelten Berechnungsverfahren erreicht worden. Dieser Beitrag soll Bauherren, Ingenieurbüros und bauausführenden Firmen für den Anwendungsfall „Brückenwiderlager“ im Bauverfahren „Bewehrte Erde“ sensibilisieren und daran erinnern, dass, bedingt durch seine zahlreichen technischen und ökonomischen Vorteile, dieses Bauverfahren bei unseren europäischen Nachbarn sowie weltweit für Brückenwiderlager nahezu als Standardbauweise gilt. A long experience in structural behaviour of Reinforced Earth for the application of bridge abutments. Since Reinforced Earth was invented in the early 60s of the last century, many retaining walls and bridge abutments had been erected using this technique. The main research of the load bearing behaviour of reinforced earth bridge abutments started more than 40 year ago. Since that many improvements by exploring scale models, measurements on test and real structures had been executed. This article shall remind clients, contractors and engineers the Reinforced Earth is combining technical and economical advantages for the application of bridge abutments.     

Langzeitverhalten feuerverzinkter Bewehrungsbänder für Bewehrte Erde Bauwerke

Long‐term behaviour of hot‐dip galvanized reinforcing strips for reinforced earth constructions For reinforced earth constructions the following parameters are found as a solution to ensure the corrosion prevention of strips for a longtime period: ? use of specific nonbinding grounds, ? preventing the penetration of salt from outside, ? choosing a zinc‐galvanized coverage with a minimum‐thickness of 100 μm. Now a corrosion induced failure of strips is almost impossible considering a building‐relevant period.     

Gesteine – Entstehung und Eigenschaften

Rocks – Formation and Properties The origin of rocks is very different and closely associated with natural processes such as volcanic eruption, mountain building and erosion. Rocks are classified in three main groups: (a) igneous rocks, (b) sedimentary rocks, (c) metamorphic rocks. Igneous rocks originate from hot magma, sedimentary rocks from erosion of preexisting rocks and metamorphic rocks from change of preexisting rocks under heat and pressure. Depending on the rock origin rocks possess different properties. Properties like interconnection, hardness and abrasion resistance influence the machining of rocks. During the machining of metals which have predominantly homogenous structure chips are generated. The machining of rocks is rather a brittle fracture combined with a grinding process. Knowledge about rock properties like abrasion resistance is necessary to adjust the machining tool for varying rocks.