Ikea Dortmund “Applied” Use of FEM for a Compaction Grouting Project Settlement control of a high-rise warehouse in Ruhrgebiet, Germany, after partial completion of the raft foundation is a case history for the efficient use of compaction grouting during an ongoing building project. To develop numerical modeling of compaction grouting, the authors simulated the grouting process in a test area of the warehouse through a finite element model (FEM). The authors used FEM soil- structure analysis to confirm/predict results with regard to problem cavities and loose soils causing settlement. The team simulated a loading test through the same FEM before and after the simulated grouting process, and compared the calculated ground improvement with the in-situ loading test results. IKEA Distribution Center In 2001, a 71,000 m² (764,000 sq ft) distribution center was built in Dortmund- Ellinghausen, Germany, on behalf of the Swedish furniture company, IKEA. In the center of the warehouse, contractors built a high-rise storage area on a 40 cm (15.75 in) thick raft foundation. The subgrade was built by a 1.5 m – 2.0 m (5 ft – 6.5 ft) thick, compacted fill of mine waste—a very heterogeneous, mainly coarse material containing boulders and partial vugs. Below the compacted fill, contractors found boulders up to a depth of 14.5 m (47.5 ft). Between 3.5 m (11.5 ft) and 14.5 m (47.5 ft), the mine waste was very loose. 40 • DEEP FOUNDATIONS • JULY/AUG 2012 Engineers explored the density with 17 cone penet rat ion tes t s and 10 supplemental dynamic probing tests. Due to the boulders, the density of the mine waste was difficult to explore. Taking that into account, the determined equivalent average tip resistance for the mine waste was approximately 50 bar (725 psi). Before construction was completed, proceeding settlements occurred of 4 cm (1.6 in) to exceeding 12 cm (4.7 in) on an area roughly 10,000 m² (107,600 sq ft). In 2002, CDM Consult GmbH was retained for an arbitration opinion and then contracted for the design and technical site management of the rehabilitation. Contractors determined that the subgrade composition was the primary cause of the settlements resulting from the comparably moderate loads of the incomplete construction. To stabilize the building, CDM recommended compaction grouting, which needed to be designed and performed in a very short time. Field tests provided the following data: injection rate of 40 – 80 L/min (10.6 – 21.1 US gal/min), AUTHORS: Antonios Anthogalidis, Dipl.-Ing. Research Fellow, and Ulvi Arslan, Dr.-Ing., Professor Technische Universität Darmstadt Peter Priggert, Dipl.-Ing., Project Manager, CDM Consult GmbH injection pressure of 26.0 – 40.0 bar (377 – 580 psi), uplift GSL of 0 mm, injection volume per m depth of 400 – 800 L (106 – 211 US gal), and grid spacing every 2.00 m (6.56 ft). From May to August 2002, contractors produced 3,310 compaction grouting columns using 16,560 m³ (21,660 cu yd) of grouting mortar. Loading Test Area. Engineers per- formed three loading tests (using pre-cast concrete segments) to verify any improve- ment from the grouting. Loading test BV 2 achieved the most significant results with a loading of p = 40 kN/m² (835 psf). Loading Test Area BV 2 To compare improved and non- improved mine waste, contractors verified compaction with four dynamic probing tests before compaction and six tests after compaction. Engineers measured settle- ment before, during and after compaction with 16 geodesic leveling points and one extensometer in the test area. The extenso- meter measured vertical displacement in depths of 4 m, 8 m, 12 m, 18 m and 24 m (13 ft, 26 ft, 39 ft, 59 ft and 79 ft).
