Two case studies of movement and damage in relatively new domestic dwellings

This paper presents cases of damage in two dwellings in Victoria that occurred because of soil movement. The paper explains the mechanisms of movement that lead to the damage, based on site specific geotechnical investigations.

In the first case study, significant localised heave occurred beneath the front section of a residence supported on a slab founded on a highly reactive, compacted clay fill. The other sections of the slab exhibited little movement. No site drainage issues were observed around the front of the building, where the heave has occurred. The front section of the slab was constructed over an access roadway for heavy earth moving machinery that was required during development of the estate were the house was built. The effect of the heavy machinery traffic on the performance on the fill, and therefore, on the slab is examined and discussed in this paper.

The second case study relates to significant localised heave beneath the front of another residence supported on a slab founded on highly reactive clay soil. The other sections of the slab exhibited little movement. The subject site sloped from front to back, requiring site levelling works. As a result of these works, the front section where the heave has occurred, is located within a site cut constructed just prior to the construction of the slab, whilst the rear section of the slab is suspended on deep piers over the filled area. The effect of the site cut, undertaken just prior to slab construction, on the performance of the slab is examined and discussed in this paper.