Diplomityö: Pohjanvahvistuksen optimointi osana vähähiilistä esirakentamista

Abstract In this thesis, different ground improvement methods were planned for an imaginary site in northern Helsinki. After geotechnical calculations, emissions and expenses were calculated for each case. Ground improvement methods in question were column stabilization, preloading and overloading embankments, vertical drains, and lightweight materials. Every method was designed by changing variables such as underneath clay layer thickness, allowed settlements, embankment height, or available preloading time.

Carbon dioxide equivalent emissions and expenses were calculated for each case, after which cases with different parameters were compared with each other in terms of emissions and costs. At the same time, optimization potential for each method was determined, meaning evaluation of how substantial reductions in emissions and expenses can be achieved by for example increasing the preloading time or utilizing resources wisely within mass coordination. Additionally, different methods were compared with each other to find the lowest emission or lowest cost methods for a given case.

It was discovered that most cases lower emissions also meant lower expenses, as with optimization a smaller amount of materials and resources can be used. Preloading time is a significant factor with optimization as well as emissions and expenses, and it affects both the choice of method and the design within a method. Increasing the settlements also leads to considerable reductions in emissions and costs. All the studied methods have room for optimization. With careful planning and adequate construction time, ground improvement can be implemented with lower carbon dioxide emissions and expenditure. Keywords preconstruction, ground improvement, emissions, cost accounting, column stabilization, preloading, settlements.