SPS - Slot Pile System

Repairing and installing safety measures at the Arapuni dam in New Zealand was a project that was among the most technologically important in the field of civil engineering. In particular, the work performed by Soilmec, by the main contractor Brian Perry Civil, called for a series of precision drilling tasks. The slot cavities created were then filled with concrete, which formed a waterproof diaphragm under the dam.

The implementation procedures for the drilling had unique characteristics, and the task was achieved thanks to the competent support offered by Trevi during the process of defining the project and their fundamental contribution was made possible by their ability to count on the most advanced and sophisticated drilling devices, through Soilmec.

SPS on Soilmec Machines

On the basis of the experience they acquired at the Arapuni dam, Soilmec Research and Development began a project for specialized excavation tools to create “guided secant piles” to be used in dam repair projects. In short, the tool calls for the insertion of a down the-hole rotary drill and a guided system that allows reactive control of the direction of the excavation.

Arapuni Dam: check slot dimensions and continuity across slot.

The specifics of the solution consists in an excavation device that is supported in the hole during operation through a lifting mechanism and that includes an exchange motor. The opening can be partially filled with excavation fluid, and the detritus evacuation system uses reverse circulation so that the excavation debris is transported to the surface through a flexible tube that is wound up in a special coiler.

Arapuni Dam: drill adjacent hole with guide in adjacent hole.

The tubes and the electrical cables necessary for operation and control of the unit are controlled in the same way, including measurements and corrections relative to its position.

Project sketch of new equipment.

With respect to the solutions developed and applied at the Arapuni project, the new jig decreases excavation times since it is no longer necessary to insert drill pipes, which are replaced by tubing, allowing monitoring of excavation parameters and reactive control of the gradients.