Application Of Soil Nails In Urban Infrastructure Development

The South East Transit Project Section 2 (SETP2) in Brisbane was recently constructed to provide a dedicated traffic corridor for public buses and emergency services vehicles. The project route, of a length of 2.1 km, traversed densely populated areas which imposed significant constraints to the construction work. One of the many challenges of the project was to carry out excavations within a narrow project corridor. As a result, steep cuts were inevitable. The stability and serviceability of these excavated batters were of paramount importance due to the presence of the existing facilities and properties in the proximity. A cost-effective solution to overcome such problems was to use soil nails to strengthen the ground behind the excavation and minimise disturbance to the surrounding areas. With careful design and construction considerations, soil nails have been extensively used on this project to provide support to steep cut batters. One of the most critical excavations for the project was located south of the Cleveland Railway Line and alongside the existing South East Freeway, a major arterial road in Brisbane. The excavation was up to 20 m deep with near vertical cut faces separated by berms. The soil nails have been successfully installed through the embankment fill and have maintained stability of the excavation and restrained ground movement in the existing freeway.