Lyttelton Port Company Cashin Quay 1 Earthquake Repairs

Temporary repairs were required at Cashin Quay 1 wharf, as a result of extensive damage from the 22 February 2011 earthquake. The project involved the construction of a ‘temporary’ piled steel superstructure to support a 200 tonne coal shiploader.

Location

Christchurch, New Zealand

Client

Lyttelton Port Company

Project Status

Completed: 2012

The structure needed to be constructed within the same footprint as the existing wharf, while maintaining vessel and coal loading operations. One of the innovative aspects of the project was the way the shiploader was supported to allow continuity of coal export operations following the 13 June 2011 earthquake, when the shiploader came perilously close to being lost when the existing timber piles supporting it fractured.

CLIENT BRIEF/PROJECT CHALLENGES

The project began following the 22 February 2011 earthquake with stabilisation works, indicative pile sizes, structural form, and cranage requirements developed and mobilised in the first few days.

The project was highly complex across several levels, including:

Technical complexity due to insurance policy constraints.
The need to maintain wharf operations for vessel movements and coal loading throughout the construction period.
Geotechnical challenges due to a weakened and displaced reclamation slope.
Complexity due to on-going seismic activity causing further damage and movement to the existing structure and reclamation

OUR SOLUTION

The project involved installing unfilled tubular steel piles through the edge of the Cashin Quay reclamation and underlying soft sediments. The piles were designed as friction piles to resist the vertical loads, which were confirmed by dynamic pile testing.

The piles were designed to be adequate as temporary repair works but the layout was such that they could be extended to greater depths and incorporated into a replacement wharf, if/when this became necessary.

This project was designed and constructed during the seismic activity of the 2011 Canterbury earthquakes. Given the changing seismic design requirements, the analysis included use of finite element models utilising scaled numerical time history records developed by WSP. The work used similar sophisticated processes to the analysis performed in support of the insurance claim that was peer reviewed by world renowned experts.

One aspect that made the project so challenging was the need to keep the shiploader operational throughout the construction programme. By working closely with LPC, initially loading of bulk vessels from a single point was implemented, by moving vessels up and down the berth in a particular sequence to avoid causing structural damage to the vessel by unbalanced loading. After the 13 June 2011 earthquake, support to the shiploader was compromised. As a solution, an innovative steel truss design, spanning up to 36m, was designed and installed within an 18 day period to reinstate support to the shiploader.

The temporary repair works were minimised by careful consideration of the Level of Service that was actually required just for coal operations, yet locally retaining a heavy duty area for unloading of car ships.

OUTCOME/CLIENT BENEFITS

LPC was very happy with WSP’s dedication and adaptability to this challenging project, and in achieving the key project requirements, especially those in relation to compliance with their insurance policy and satisfying their own client’s requirements to continue to export coal throughout the construction works.

The success of this project was achieved not just by innovative engineering design, but also by client/consultant/contractor relationship, which worked collaboratively on a ‘best for project’ basis.

The project was completed within its allocated budget based on the full scope of works defined after the 13 June 2011 earthquake.

KEY FACTS

This project received an ACE New Zealand Innovate Silver Award for an Outstanding Project
Access limitations required the use of 400 tonne and 280 tonne cranes positioned on a specially constructed piled support beam, to prevent excessive loading near the edge of the reclaimed (and failing) land.
The final design was continually refined based on damage caused by ongoing earthquakes.
Primary structural elements consist of:
80 tubular steel piles driven to 48m below deck coolismic loads.