Soil-Structure Interaction of a High-Rise Building Near Sensitive Structures in Soft Soil Conditions-Paper

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The paper examines the soil–structure interaction of a planned 75 m, 22-storey hotel beside the River Main in Frankfurt, Germany. The site is underlain by variable artificial fill, alluvial clay, sand and gravel, and deep tertiary marl. The new building will stand beside more than 100-year-old quay walls, bridge abutments, and a pile-founded roundabout, making protection of existing infrastructure a key design concern.<br /><br />The hotel’s heavily eccentric 507 MN load will be supported by a Combined Pile-Raft Foundation (CPRF): a 2 m-thick triangular raft and 34 piles, each 1.5 m in diameter and 40–45 m long. Three-dimensional, nonlinear finite-element analyses using PLAXIS 3D modelled the soil, structures, foundation elements, loads, and sequence of construction across the site. The model comprised approximately 772,000 elements and incorporated the area’s construction history.<br /><br />The analyses predicted hotel foundation settlements of 2.5–4.5 cm. Settlements of the existing bridge abutments and roundabout were estimated at up to 2.5 cm, while quay-wall settlements were predicted at 1–3 cm. Maximum quay-wall angular rotation was 1/1,000, within the cited 1/500 damage-prevention criterion; predicted horizontal movements were no greater than about 0.3 cm. The authors therefore expected no damage to the historic quay walls or other existing structures. Differential settlement of 0.5–2.0 cm is expected at the connection between the hotel and the roundabout’s underground levels, so this passage must be designed to accommodate movement.<br /><br />The study concludes that detailed three-dimensional numerical modelling is essential for assessing the stability and serviceability of complex, eccentrically loaded foundations near sensitive structures.

Keywords

soil-structure interaction

combined pile-raft foundation

finite element analysis

PLAXIS 3D

foundation settlement

eccentric load

quay wall

historic infrastructure protection

differential settlement

Frankfurt hotel