RENOVATION OF AN OLD SALES CENTER FOR ADDITIONAL UNDERGROUND PARKING-Paper

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The paper describes adding underground parking beneath an existing two-storey sales center in Shijiazhuang, China, where limited space made above-ground parking impractical. The original steel building had no basement or parking, and its upper level and public operations needed to remain open throughout construction.<br /><br />The project created an 8-by-10-metre basement, 7.65 metres deep, with mechanical parking for four cars. Before excavation, the building’s four columns were underpinned with 16 screw anchor piles (SAPs), each 24 or 25 metres long. Steel micropiles and staged bracing supported the excavation. The SAPs were drilled into the ground and grouted to serve as permanent temporary supports; after the basement structure was completed, the building’s load was transferred to the basement walls and raft foundation.<br /><br />Construction began in early 2016 and finished in May, including installation and testing of the parking equipment. Compact drilling equipment suited the constrained site. Numerical analysis informed the design and predicted a maximum SAP load of 138 kN and settlement of 1.79 mm. Monitoring recorded maximum column settlement of 2.5 mm, with no observed wall cracking. Instrument readings and load tests on three piles confirmed that pile forces remained within expectations and that the piles had sufficient bearing capacity.<br /><br />The building remained operational during the work, and the renovated exterior was largely unchanged apart from a new parking entrance. The authors conclude that underground parking beneath existing buildings can help address space shortages in city centers, while noting that further study is needed to verify SAP performance under different site conditions.

Keywords

underground parking

existing building retrofit

screw anchor piles

basement excavation

micropiles

structural underpinning

mechanical parking

settlement monitoring

urban space constraints

Shijiazhuang China