Resumen
The geotechnical conditions of the soiland the construction conditions of aretaining wall for an underground twolevelcar park project are described.The project is located in Concepción?sdowntown, south of Chile. The excavationsupport had to prevent any damage forthe Courts of Justice historic buildingand surrounding buildings. These arebuildings between four and nine floorsand the Hites building is also classifiedas a historical building. Also, any cutoffof water, sewage, gas and electricityhad to be avoided. The solution adoptedwas an anchored soldier pile wall of 8 mdepth around the excavation, where thesoldier piles (H section steel piles) weredriven into semi dense silty sand. Twolines of anchors were designed verticallyand horizontally separated by 3 m and3.2 m respectively. The design loads forthe anchors ranged between 300 and560 kN respectively. The installation andplacement of anchors was studied inorder not to disturb the different stagesof construction. The project included3596 m2 of anchored soldier pile wallwith 314 post-stressed anchors and300 soldier piles totalling 3200 m. It isconcluded that the temporary excavationsupport solution adopted performedproperly to the high demands set, sinceno important deformations were notedin the building of Courts of Justice, in thesurrounding buildings or in the services ofdrinking water, power, gas or electricity.The city of Concepción was severelystruck by an 8.8 moment magnitudeearthquake on the 27th February 2010.The construction of the underground carpark was just ready when the earthquakeoccurred. No damage was observed inthe car park due to the seismic event.It is believed that the buried soldier pilewall reduced the seismic loads acting onthe underground car park structure sinceno evidence of damage exists after thevery big earthquake.Keywords: Anchored soldier pile wall, silty sandy soil, excavation support constructionsequence.