Foundations

Introduction

DYWIDAG Post-Tensioning Systems are world renowned for reliability and performance, most suitable for all applications in post-tensioned construction. They embrace the entire spectrum from bridge construction and buildings, to civil applications, above and below ground. The first ever structure built with a prototype DYWIDAG Post-Tensioning System using bars was the Alsleben (Germany) arch-bridge in 1927. From that time on DYWIDAG has continuously improved its systems to keep up with the growing demand of modern construction technology. DYWIDAGSystems International (DSI) offers a complete product line in strand and bar post-tensioning (bonded, unbonded and external) as well as stay-cables being able to fully serve the post-tensioning construction industry.

Dywidag Ground Anchoring Systems

DYWIDAG Post-Tensioning Systems have always combined the highest safety and reliability standards with the most economical efficiency in their research and development. Dependable corrosion protection methods incorporated into the DYWIDAG Post-Tensioning Systems contribute to the longevity of modern construction. High fatigue resistance is achieved with optimized material selection and careful detailing of all components especially in their system assembly. DSI looks back on many years of valuable experience in the field of post-tensioning which leads to our extremely versatile product range that offers economical solutions for practically any problem. This includes our highly developed, most sophisticated field equipment which is easy to operate in all phases of installation including assembly, installation, stressing and finally grouting. DYWIDAG Post-Tensioning Systems are being developed and maintained by DYWIDAG-Systems International and are serviced and distributed by a worldwide network of subsidiaries, licensees and agents. Our systems comply with the different national and international specifications and recommendations (ASTM, AASHTO, BS, Eurocode, DIN, Austrian Code, SIA, FIP, fib, EOTA, etc.).

The technique of soil nailing began to evolve in the early 1970's. Major research programs in Germany in the mid to late 70's and in France in the late 80's advanced this method of construction. It has been successfully utilized worldwide for excavation support and slope stabilization and its use continues to grow rapidly. General Notes Applying the principles of systematic rock anchoring to soil seems to be obvious, but the requirements for soil nailing are higher. The many years of experience gained with pressuregrouted anchors have resulted in a certain level of standards, however, the stability of the supported soil mass must be verified for all stages. Soil nails are used for stabilizing slopes and excavations. They find an efficient application in granular soils of medium to high density with sufficient internal friction, so that a good load transfer along the soil nail is possible, and only slight creep movements occur in the supported soil mass. The soil nails are installed as the excavation progresses from top to bottom. The surface of the cut is usually stabilized by shotcrete and rebar mats. Since the soil nails are loaded only by ground movement, a certain outward deflection of the top of the stabilized wall must be expected. The theoretical pivot of the wall is at the bottom of the excavation. Calculations assume the maximum tensile force in the ...