City North, Finsbury Park, London

Mark Creighton

Mark Creighton

Director

Tel: 020 3096 7567
Email

Client

Telford Homes/Walsh Associates

Services

  • Ground Movement Assessment
  • Analytical Reporting
  • Numerical Analysis and Finite Element Analysis
  • Global Stability Checks

Ground movement assessment for London underground tunnels, rail lines and party walls

Telford Homes is redeveloping the City North site in Finsbury Park, North London into a combination of residential and business developments with Walsh engaged as the structural engineers.

The redevelopment of City North includes demolition of the existing buildings and construction of four mixed use buildings up to 23 storeys high, a podium two to three storeys high and an additional two-storey basement to be constructed beneath the site. The site borders Finsbury Park Station and Network Rail (NR) lines.

CGL was commissioned by Telford Homes to provide a ground movement report based on Finite Element Analysis (FEA) to enable the assessment of the potential impact of construction works on infrastructure adjacent or close to the site, namely NR assets (rail tracks and Finsbury Park Station) and London Underground (LUL) Piccadilly and Victoria Line tunnels. Ground movements on party walls were calculated with software packages such as Oasys PDisp and Geosolve WALLAP.

Bulk earthwork excavations and installation of contiguous piled retaining walls are proposed along the entire basement perimeter to enable the construction of levelling platforms for foundation piling, and also to enable the construction of the basement and lower ground floor slabs.

CGL developed a 3D FE model of the site to simulate the historic and proposed development stages and their effects on the ground properties and behaviour. The results were extracted for processing and assessment.

The model provided a complete 3D picture and understanding of ground movements with depth and distance, stresses developed within the ground, ground water pressures as well as deformations, section forces and stresses on underground structures (retaining walls and Piccadilly Line tunnel). The results were summarised in a Ground Movement report for NR and LUL.