Abstract
For the "Unterföhring Tunnel" BAUER Spezialtiefbau GmbH, worldwide acting in special foundation construction projects, carried out bored pile walls using their recent technology of the double rotary drive system. The supervising building authority carried out control measurements, which showed that apparently the concrete cover was in accordance neither with the contract requirements nor with the German Standard. Therefore very thorough quality checks were conducted on a very large scale which resulted in an expert statement which certified full bearing capacity and full serviceability of the tunnel frame for the required service life of 100 years - without any restrictions. Therefore no repairs were necessary at all. The double rotary drive system allows drilling a bore hole while retaining it with a steel casing in one production process. While the drilling auger filled with soil is being extracted, concrete is being pumped in through the core of the auger. This means that the reinforcement cage has to be installed into the fresh pile concrete afterwards. The newly acquired knowledge made BAUER improve the double rotary drive system as to device and procedure, thus ensuring state-of-the-art bored piles for the future, even under demanding conditions as in Unterföhring.
| Translated title of the contribution | Extended quality checks for proof of sufficient concrete cover in reinforced concrete bored piles |
|---|---|
| Original language | German |
| Pages | 434-442 |
| Number of pages | 9 |
| Volume | 82 |
| No | 7 |
| Specialist publication | Bautechnik |
| DOIs | |
| State | Published - Jul 2005 |