NZ International Convention Centre

Services: Ground Anchors

Main Contractor: Fletcher Construction

Engineer: BECA

Grouting Services wins the SME awards for Category B (projects over $500,000) at the 2017 Hynds Construction Awards.
David Sharp

Grouting Services is proud to be supporting Fletcher Construction on the the NZ International Convention Centre (NZICC) and Hobson St Hotel. Grouting Services scope of work included the design and installation of the perimeter ground anchors. Fletcher Construction will build the NZICC, the 5-star Hotel with a combined project cost of $700m and at least 1000 construction jobs over 3 years. The NZICC is one of the most significant building projects in Auckland since the construction of the Sky Tower – also built by Fletcher Construction and retained by Grouting Services 22 years ago.

The perimeter retention system comprised bored-insitu piles restrained with actively stressed temporary ground anchors. Prior to production works commencing, proving trial anchors were installed to verify the geotechnical ultimate bond rupture and this ranged from 1150kPa to 1500kPa in the waitemata series sandstone. The trial anchors comprised 14No x 15.2mm strands (3,570kN UTS) with a 3m bond and 15m free length in a 150mm diameter drill hole. A design geotechnical ultimate bond stress of 600kPa was used and based on the testing factors of safety ranging from 1.8 to 2.5 were demonstrated.

In total nearly 600No multi-strand temporary and removable compressive distributive ground anchors will be installed around the perimeter to complete the retention works. The design of the multi-strand anchors was governed by a stiffness requirement set down by project consultant BECA and the tendons ranged from 7-10 x 15.2mm strands (UTS 1,827 - 2,610kN), 15m to 30m long. As part of the project consent conditions, Auckland Transport included a requirement for removable anchors along Nelson Street to ensure there would be no impact future services. The technology for the removable compressive distributive (SW-RCD) anchors was developed by Samwoo, the leading representative of ground anchors in Korea. Grouting Services has a distributorship agreement to both supply and install anchors from Samwoo in New Zealand.

The anchors were either terminated through the piles and fixed into a bespoke steel corbel designed by Grouting Services, or anchored into a concrete capping beam. In some locations, steel walers were utilised.

Due to a variety of access and programming constraints, multiple drilling rigs were utilised to successfully put the anchor holes down.

In addition to the perimeter retention works, Fletcher Construction engaged Grouting Services to carry out some slope projection works in the form BluGeo GRP bars and mesh.

The Grouting Services team was also contracted to construct ground support works for the Nelson House facade as part of the NZICC project. An innovative solution that incorporates low strength concrete and BluGeo GRP bars was proposed by Grouting Services as a value added solution. This incorporated a row of 300mm dia piles that underpin a supporting capping beam. The capping beam in turn supports a superstructure that provides lateral restraint to the existing facade and will remain in place while the building is demolished and the basement excavated for the NZICC. 

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