Project: Kokoda Apartments
Location: Milton, Brisbane
Contractor: Mainland Civil
The Kokoda Apartments project was to comprise of a 19-level residential tower over a 5-level basement carpark, with the required finished slab level varying between RL -6.7m to -9.3m.
As the building was located in the inner-city, there was limited access and space for machinery and equipment. As a prerequisite for construction, the builder had to construct a piling platform with an axial loading capacity in excess of 122 tonnes for the movement of heavy machinery.
Polyfabrics Australasia was contracted by Mainland Civil in August 2017 to supply products that would help with soil separation and stabilisation of the pavement that would be used for shoring works.
A geotechnical investigation of the soil revealed “weak” soil/rock profiles, with various fractures within the stratum which could cause failure if exposed to large surcharges. In contrast, field SPT tests found the upper layers to consist of strong sandy clays with low blow “N” values under undisturbed moisture soil conditions. Mainland Civil required a solution that would prevent the intermixing of different soils and stabilise the subgrade interface, in order to construct the pavement.
Polyfabrics proposed the TerraStop® 204 coaxial 85/85KN/m, a high-tensile product manufactured from durable, high-modulus PP yarns and woven into a robust, dimensionally stable geotextile. As the construction of the Kokoda pavement was only a temporary one, TerraStop® proved to be the most cost-effective solution in comparison to other products. The use of this solution also provided the following benefits:
- Ease of use and available in favourable roll sizes
- An outstanding tensile strength at 25% elongation (suitable for differential settlements). Has retaining strength of 30KN/m at 5% strain
- Filtration and separation of cohesive layer which means the additional non-woven geotextile underneath was eliminated
- CBR puncture strength allowed for unloading ungraded crushed rock thereby eliminating the risk of poor interlocking effects commonly seen with Geogrids
Mainland Civil was pleased with the solution and implementation of TerraStop®. The TerraStop® Geotextile was able to separate and stabilise the soil which helped them to commence engineering works on the site confidently. As an incredibly strong product, it could withstand the weight of the machinery being offloaded onto the pavement.