EDIFICIO PIEDRA REAL – CONCEPCION, CHILE CASE STUDY OF AN UPLIFT REINFORCEMENT PROJECT-Paper

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The Piedra Real project in Concepción, Chile, comprises four 18-storey residential towers with two underground parking levels founded on a large reinforced-concrete slab. Shallow groundwater created significant hydrostatic uplift, while the region’s high seismicity and local soil conditions added design challenges.<br /><br />Permanent foundation reinforcement was provided by self-drilling, grouted TITAN micropiles installed beneath the slab. The piles transfer tensile loads to dense sandy soil through shaft friction. Design followed German geotechnical standards, using partial safety factors, and accounted for structural capacity, pull-out resistance, and long-term corrosion protection. A specified grout cover protects the steel for a design life of 100 years.<br /><br />Three micropile types were installed, with design tensile loads of 40, 53, and 71 tonnes. Load tests reached up to 90% of the steel yield force without triggering pull-out failure, supporting the design assumptions. Measured movements at design loads were 9–13 mm, and inspections confirmed grout cover exceeded the required minimum.<br /><br />The micropiles also improved construction planning. Compared with an initial scheme involving a 2.5-metre-thick foundation slab, the adopted approach reduced the excavation depth from 9.5 to 7.6 metres. This enabled optimization of the temporary soldier-pile shoring and groundwater-lowering systems. TITAN tension piles were also used to support the excavation wall, allowing the same equipment to install both anchors and foundation micropiles and reducing construction time and logistics costs.<br /><br />The case demonstrates how micropiles can provide effective uplift resistance while reducing concrete demands and improving coordination with excavation works. The authors note that similar systems may be suitable for infrastructure such as underpasses, tunnels, and caissons.

Keywords

Piedra Real

Concepción Chile

residential towers

micropiles

foundation reinforcement

hydrostatic uplift

seismicity

grouted TITAN micropiles

load testing

corrosion protection