University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Master / Diploma Thesis:
Martin Koller
(2010):
Modellierung des Frischbetondrucks in Bohrpfählen.
Master / Diploma Thesis - Institut für Geotechnik (IGT),
BOKU-Universität für Bodenkultur,
pp 140.
UB BOKU
obvsg
- Abstract:
- In foundation engineering the use of soft concrete with consistency ≥ F59 leads to problems caused by instability of fresh concrete. Due to release of water, also called bleeding of concrete, damage can arise on the surface of construction elements or along reinforcements. Bleeding of concrete is influenced by a number of factors. One of these factors is the pressure of fresh concrete. The data in the literature are mainly from surface buildings. Those measurements show that the pressure of fresh concrete depends primarily on the concrete consistency and the speed of concreting. To determinate the pressure of fresh concrete some measurements have been carried out in bore piles in this work. Those were done with pressure pads with an electric pressure transducer in different dephts along the piles. To get longterm pressure development the measurements were carried out over the duration of several days. The pressure of fresh concrete can be determined by different calculation models. In this work, the pressure is calculated with two different approaches and is compared with the data on site. The first calculation model is based on the earth pressure theory of Coulomb with the special case of earth pressure at rest. The important parameter is the friction angle of the fresh concrete. As the second model, the method of Proske/Schuon is used. This model is based on the silo theory and considers friction coefficients as well as the end of setting of concrete. The calculation results show that the pressure above some 21 meters can be assumed to be hydrostatic. At depth larger than 21 meters the silo effect has substantial influence on the pressure of fresh concrete.
- Beurteilende(r): Wu Wei