Innovative Earth Retention Project for a parking garage-Paper

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The project involved constructing a nearly 200-meter-long parking garage in Ischgl, Austria, with capacity for more than 600 cars and buses. Located beside a hill, village road, and stream, it required an excavation up to 25 meters deep close to existing buildings. Neighbouring property owners prohibited drilling anchors beyond a narrow, 7-meter-wide strip, while the ground varied from poorly compacted fill to heterogeneous river sediments containing enormous boulders.<br /><br />The design team developed a permanent excavation-support system combining vertical and inclined micropiles, prestressed tieback micropiles, soil nails, and reinforced shotcrete. Together, these elements formed an anchored soil mass while meeting strict space and deformation limits. Because ground conditions were inconsistent, the garage was supported on driven, injected iron piles, with pile lengths determined from on-site driving measurements.<br /><br />Construction required adapting the design as conditions changed, including an extension for a municipal building and a later tunnel entrance. Large boulders complicated drilling and excavation, and a twice-weekly surveying program tracked wall movements. Maximum measured deformation was 45 mm, within the 50 mm limit.<br /><br />The garage opened in November 2015, on schedule and without accidents or major problems. The project demonstrated the value of integrating geotechnical and structural design, tailoring support systems to site constraints, maintaining close site supervision, and monitoring ground movements throughout construction.

Keywords

parking garage

Ischgl

Austria

excavation support

micropiles

soil nails

shotcrete

tieback anchors

geotechnical engineering

ground deformation