Foundation Anchoring for Stability in Brownfield Site-Paper

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This case study describes the foundation design for a heavily loaded coke-breeze storage silo at an operating steel plant. The silo’s location among existing facilities created major brownfield constraints: the planned raft foundation extended beneath an active road, and excavation revealed a live 700 mm water pipe that could not be relocated. Plant operations could not permit the road closure originally planned, so the foundation footprint had to be reduced to avoid both obstacles.<br /><br />The reduced raft area could not safely resist the silo’s seismic overturning forces. Analysis showed uplift and tensile contact pressures beneath the foundation, threatening stability. Engineers therefore revised the design to use rock anchors placed around the raft perimeter, where tension was concentrated. The anchors were un-tensioned dowels: 16 mm reinforcing bars chemically anchored 300 mm into the underlying mica-schist rock and extending 600 mm into the raft concrete.<br /><br />Three sample anchors were pull-tested to a proof load of 36 kN without failure. The revised analysis found a maximum anchor demand of 10.6 kN, giving a capacity-to-demand ratio of approximately 3.4. The design also checked bond and development lengths for anchorage in rock and concrete.<br /><br />The solution provided the required foundation stability within the available footprint and allowed construction to proceed without diverting the water pipe, closing the road, or interrupting plant operations. The study illustrates how site investigation, structural analysis, testing, and adaptable foundation design can address construction constraints in brownfield environments.

Keywords

coke-breeze storage silo

foundation design

brownfield constraints

raft foundation

seismic overturning

rock anchors

mica-schist rock

water pipe obstruction

pull testing

steel plant