Basic Concept
The AT – Pipe Umbrella System is installed using conventional drilling machines. Single pipes are installed piecewise at a length that fits the drill boom length. Type and quality of the pipe coupling are decisive factors for the maximum achievable load-bearing capacity of the support system. For this reason, three different types of couplings are available for the AT – Pipe Umbrella System.Standard Thread Connection
- Installed tubes show a constant inner diameter
- The stiffness and strength of the connection is considerably lower than those of standard pipes
- The rupture load of the connections is comparable to the design load of standard pipes; it is clearly lower for non-calibrated tubes
- Further decrease of the load-bearing capacity if mistakes occur during connecting or grouting of the pipes
- A lower load-bearing capacity can only be compensated by a higher number of pipes
- Dislocation of the coupling positions in the longitudinal direction does not significantly increase the load-bearing Capacity
- Installation can be accomplished with or without an AT – Pipe Umbrella Automation Unit
Squeezed Connection
- Simplest connection type
- The ultimate load of this connection is considerably higher than the elastic design load of a normal pipe (> 1.5)
- Transition from elastic to plastic material behavior begins at approximately 2/3 of the elastic design load (standard pipe)
- Reduction of the inner diameter in the connection area
- Reduction of the stiffness against bending in the connection area
- Installation is accomplished with a so-called AT – Squeezing Unit, preferably in combination with an AT – Pipe Umbrella Automation Unit
