Transportable house failure in collapsing soils at Port Broughton, South Australia

In May 2000, a transportable house, which was being relocated to Port Broughton, South Australia, collapsed without warning. The practice generally adopted to erect such houses involves the use of mechanical jacks. Prior to the collapse, six jacks were supporting the house, which was raised approximately 1.5 m above the ground. While precast concrete footings and tie-downs were being installed the house fell from its jacks. Of the six people on-site at the time, four were beneath the house, two of whom died as a consequence. This paper outlines a forensic engineering investigation undertaken by the author to determine the cause of the collapse and focuses on the geotechnical aspects of the accident. It is demonstrated that the procedure commonly used to erect transportable houses is inherently unsafe, especially when the ground profile incorporates collapsible soils.