CASE STUDIES

Situation:
The Britomart tunnel was being widened, to accommodate a new train line as the Metro Line below Auckland City was being upgraded for faster trains. The main tunnel wall which was 400mm thick was supporting the load of a fifteen-storey building above it. Meccanico undertook the engineering works, which included the designing of the temporary structural steel to support the demolition but more importantly the methodology and calculations of the technical jacking of the existing wall and the transferring of the load onto the new wall. The new wall was to be constructed in advance. During this construction phase we were also engaged to monitor and record data of the possible displacement or deflections of the walls and tunnel soffit. During this construction phase, we received notifications and data every fifteen minutes, via digital nodes. This information was used to keep a history of movement and displacement within the tunnel construction. Once the new wall was built, slots were cut into the existing wall for the double acting 250 tonne locking jacks. These jacks were installed into specific gridlines so we could systematically jack the wall using our synchronised system, to the target loads, rather than height. The system had to have a specific programme and specific setup so the procedure could be closely monitored by our team of technical engineers during the loading phase.

On completion of achieving our target loads, the jacks were set into the mechanical locking phase. While the jacks were locked, the existing wall was to be cut. This meant that the full support of the structure was bearing only on the jacks. Next we activated the lowering cycle. Whilst the jacks were incrementally lowered we monitored the loads, via our computer. We were also able to cross check the loads against the digital independent system to ensure both were reading accurately. In this phase we were not trying to actually lower the load by way of measurement but more by way of load monitoring to ensure the load was transferred slowly and correctly onto the bearings and the new wall.

Challenge:
The challenges for this project were managing the sequence of technical tasks involved in the jacking process and the significant weight of the load being transferred from the old tunnel wall to the new tunnel wall. This had to be done incrementally by controlling the load in a negative cycle. During this phase of calculations we carefully lowered the jacks into decompression.

Solution:
Meccanico designed the engineered, temporary works plan as well as the engineered methodology. This included calculations of what specific equipment could be used to achieve the best outcome for the lift and lowering process. We purchased twenty, 250 tonne, locking jacks from our partner, Holmatro and flew back to Amsterdam for further training. This was to ensure the project would be executed accurately and efficiently for Martinus Rail , NZTA and Kiwi Rail.

“Martinus engaged Meccanico for the demolition of an existing wall inside Britomart Tunnel in Auckland CBD. Scope of works consisted of jacking to transfer load from the existing wall to a newly constructed wall, continuous monitoring of deflections, and design of all associated temporary works. Meccanico engaged Quoin to develop the temporary works design in collaboration with Martinus, Aurecon and City Rail Link Ltd. and developed the jacking methodology in accordance with the permanent works design requirements. The jacking works were completed successfully as critical path works during a rail shutdown with a very happy client as a result.

Throughout the works, it has been great to work with Meccanico as a trusted partner to deliver a robust solution, work to the program, and produce solutions where required. Impressed with the ability and flexibility of the team to get the job done. It was a pleasure to work with Rod & team!”

Martinus Rail

Moir Hill Road bridge
(Warkworth)

Situation
The ‘Ara Tuhono: Puhoi to Warkworth’ project, a 4-lane extension (18.5 km) to the Northern Motorway (SH1) from the Johnstone’s Hill Tunnels, at Puhoi, to tie-in with existing SH1, north of Warkworth, to improve the safety and connection between Northland and other parts of the North Island (Auckland, Waikato and Tauranga). Part of this project is the Moir Hill Road Bridge (weight: 1400 ton), one of the in total 7 bridges during the project.

Challenge
Meccanico, New Zealand’s specialist in heavy lifting and levelling operations, needed to lift and hold the Moir Hill Road bridge 4 mm, so the bearings could be repaired. The lifting took places in increments of 1 mm and every step the weight was monitored via a screen. This handling was required at both ends of the bridge. After completion of the bearing adjustments to the abutment of the bridge, the bridge had to be lowered back onto the bearing.

Solution
To ensure safe and controlled lifting, lowering and levelling of bridges and other heavy properties, Meccanico used a flexible, easy to handle and extremely accurate synchronized lifting system. Because complex lifting procedures also often require ‘tilting’, this feature was a ‘must-have’ in the system.

In 2017 Holmatro had developed a 2,000 ton synchronized positioning system for Meccanico with the option to determine the center of gravity (COG) and be able to weigh the load if necessary. The system is equipped with 6 double-acting pump units, each with 4 individual oil flows for all the 24 lifting points. Due to the modular set up of the system, the pump units can be placed around the object and then connected together. Thanks to this set up, the distance from the pumps to the lifting points can be kept equal and limited to the bare minimum. This results in much more stable lifting and lowering with significantly less vibration. The modular set up also provides huge flexibility; the system is easy to control and move around, without the need for any additional equipment such as a crane or fork lift: A major benefit on job sites where access is difficult and cranes cannot get access.

The pumps are linked together by means of a data cable that is connected to a portable HMI (Human Machine Interface) complete with touchscreen. The software on the system allows the user to set the exact parameters required to execute a complex lift. Should something fall outside of the given parameters (for instance an unexpected shift in weight) the system automatically stops the lift, so that the user can safely check and secure the object before recommencing the lift.

Due to the double-acting cylinders, the user has maximum control both on the lifting and the lowering action as gravity is not relied upon to lower the load.

Holmatro’s synchronized positioning system can easily be up-scaled by adding more pumps and cylinders, giving it an almost unlimited capacity in terms of lifting, lowering, levelling and weighing.

This makes the synchronized positioning system flexible and multi-usable in various applications and projects, like another Meccanico application; the lifting, lowering and levelling of earthquake-damaged properties.

Wroxton Terrace
(Christchurch)

This Fendalton home had a ribraft foundation that was out of level.

Because of its foundation type, it was the perfect candidate for our synchronised, computer controlled, levelling system. After set up the home was returned to target levels within 30 minutes.

“House Lifters were engaged to re-level our earthquake damaged two-storey, concrete house in lower Cashmere, which is on a steep site with difficult access. Engaging House Lifters proved an excellent decision. They started work on the agreed date and despite some shocking weather along the way they finished ahead of schedule.”

Neil Challenger, Whenua Trust