TRANSACTION PAPER

The design of a suspended concrete transport pipeline system

D. Aronowitz^I; N.R. Steward^I; R. Bradley^II

^INS Consultancy
^IIMurray and Roberts Cementation

SYNOPSIS

In order to deliver a quality shotcrete and concrete product underground for the extensions to the Cullinan Diamond Mine operations, it was decided to transport an innovative concrete product down a 714 m borehole through a vertically suspended 150 NB schedule XXS pipeline to the underground workings.
The concrete product batching and delivery system would be operated from surface as opposed to the current underground batching systems. The operation includes an automated surface batching plant, which delivers the concrete product through the suspended pipelines down the borehole to an underground storage facility from where the product gets delivered to the working area by further pumping or agicars.
In order to ensure the integrity of the suspended pipe ranges, a stress analysis of the pipelines was conducted for the expected temperature extremes to ensure that the applied pre-tension guaranteed that the columns remain in tension.
The loads from the pipe stress analysis were then used in a finite element analysis of the coupling connectors to determine the internal stresses under the various load conditions.
Finally a fatigue analysis of the system was undertaken to evaluate the effect of local stress raisers within the threaded coupling.
The data generated from the pipe stress and finite element analyses were ultimately used to design the top and bottom bearers and to dictate the critical aspects of the installation procedure.

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