Construction of the New Marlborough School in Kensington, London posed a unique challenge as it necessitated the integration of a new basement structure a mere 9 metres above a pre-existing 3-metre diameter storm drain. This proximity demanded a nuanced and intricate approach, involving the design of a complex basement geometry meticulously crafted around the exclusion zone of the storm drain. To ensure the structural integrity and functionality of the storm drain amid the construction activities, a detailed ground movement analysis was imperative.

To address this, a sophisticated 3D Finite Element Analysis (FEA) model was employed, encompassing both the newly proposed basement and the underlying storm drain. This model served a dual purpose: first, it demonstrated that the stress changes and distortions induced in the storm drain fell within acceptable limits, ensuring its stability and functionality were not compromised. Second, the FEA model provided essential data, including settlement, bending moment, and spring stiffness values, which were instrumental in informing the design of the basement raft. This comprehensive approach not only safeguarded the integrity of the storm drain but also facilitated a structurally sound and well-engineered solution for the New Marlborough School basement construction.

Highlights

• 3D FEA model of the complex basement geometry, underlying rc segment lined storm drain and surrounding ground.

• Simulation of demolition of old school, excavation of basement and construction of new school.

• Output of stress changes and distortion of storm drain for acceptance by Thames Water.

• Output of basement raft settlement, bending moment and coefficients of subgrade reaction for structural design.