Soil Improvement Through Rammed Aggregate Piers to Mitigate Liquefaction Risk in Storage Tanks-PPT Presentation

PPT Presentation

Pdf Summary

The presentation describes the use of rammed aggregate piers (RAPs) to reduce liquefaction risk beneath four flexible-bottom storage tanks at Mexico’s Dos Bocas Refinery. Each tank is approximately 30 m (100 ft) in diameter, with allowable total settlement of 30 cm and allowable differential settlement of 5 cm over 10 m.<br /><br />The site profile includes fill and layered clayey and sandy soils. Static settlement and liquefaction analyses evaluated the ground before and after improvement, including earthquake conditions of magnitude 7 and peak ground acceleration of 0.28g.<br /><br />The proposed treatment comprised approximately 980 RAP elements extending 12.5 m (41 ft) deep. Piers were spaced 2 m on center beneath the flexible tank bottoms and 1.5 m on center around the ring walls. Post-improvement CPT and SPT explorations were used to assess the treated ground.<br /><br />Analyses estimated free-field post-liquefaction settlements of 32–58 cm. With RAP reinforcement, predicted settlements were generally reduced to 1.5–4 cm. Static settlement calculations also reported total settlements of approximately 20–23 cm for the tank example presented. Overall, the results indicate that RAPs substantially reduce predicted earthquake-induced settlement and improve support conditions for the tanks.

Keywords

rammed aggregate piers

liquefaction mitigation

storage tanks

Dos Bocas Refinery

earthquake settlement

ground improvement

CPT

SPT

flexible-bottom tanks

geotechnical analysis