Project overview

TechnikGS was engaged to provide the foundation solution for a new 17-storey mixed use development located immediately adjacent to the existing historic Custom House building and within 5 metres of the Strathclyde Partnership for Transport (SPT) underground tunnel in Glasgow city centre. Rigorous design measures including finite analysis modelling and associated monitoring measures were implemented to ensure the safety of the underground tunnel throughout the piling process.

 

Challenges

The project faced several challenges that related primarily to the city centre environment and the sensitivity of the adjacent infrastructure. Owing to the location, a strict vibration and sound monitoring regime was necessary, in conjunction with 3D surveys of both the SPT rail tunnel and the Custom House building.

These data conveyed the position of the border between the sensitive drilled micropiles and the top-driven piling techniques to ensure no damage occurred and a cost-effective solution was still achieved for the project. A preliminary trialling and testing exercise was undertaken in advance of the main works to provide technical, cost and programme certainty.

Initial assessments of the impact of micropiles and load-shed near the SPT rail tunnel highlighted the need to consider load-isolating slip liners. However, information obtained during the trialling and testing exercise and the subsequent finite element analysis concluded that the liners were in fact unnecessary.

 

Solutions provided

A total of 886 250-mm-square precast concrete piles and 277 drilled micropiles were installed to depths of up to 22 m, capable of carrying safe working loads of 650 kN and 450 kN in compression and tension, respectively.

The project was successfully completed on programme and within budget, while minimal disruption to the city centre stakeholders and sensitive adjacent infrastructure was caused.