Comparison of constructing of an underground and open-pit parking facility within hard rock in an urban area

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Journal ISSN

Volume Title

Insinööritieteiden korkeakoulu | Master's thesis

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Date

2024-08-19

Department

Major/Subject

Geoengineering

Mcode

Degree programme

Master's Programme in Geoengineering (GEO)

Language

en

Pages

77+06

Series

Abstract

Cities are proliferating, attracting more people, where the demand for adequate parking spaces continues to rise while diminishing the free buildable space. Underground parking facilities offer a way around this problem. Building underground can be done in two major ways, either as a parking facility in a tunnel or as an open pit version. In countries where the bedrock is at a shallow depth, even open pit excavations would include hard rock excavations. Given the impact a large excavation would have on nearby existing structures, especially considering the highly disruptive nature of rock excavation techniques, it is important to assess the rock mechanical feasibility of the two options when selecting the appropriate method. Further, it is also vital to determine the environmental impact and overall cost to identify the most favorable approach. This thesis explored a case study of a rock mechanical analysis from the Meilahti hospital area where an open-pit parking facility was proposed. A hypothetical underground tunnel version of the parking facility was developed to assess its rock mechanical viability using 3DEC numerical modeling software and compared the results with the open-pit version. Further, total CO2 emissions related to rock construction works were computed using One click LCA software, and the expected theoretical rock construction-related cost of both options were calculated and compared. Simulated displacements are compared where in the tunnel version the displacements at surrounding structures were ranging from 2…3 mm. In comparison, in the open pit version, the simulated displacements are rather high, even more than 10 mm at some locations. Higher displacements could result in severe fractures in the existing tunnel's shotcrete layer, as well as foundation settlement in surrounding structures, causing shear cracks in the walls. In terms of CO2 output, both variants emit a closer level of CO2 with a slightly low percentage difference in the tunnel version. Further, there was a considerable difference in the total rock construction-related cost where the open pit version would cost nearly 1.5 times as much as the tunnel version. These results can be used as a base guideline to determine the best alternative in densely populated urban regions for any planned underground structure

Description

Supervisor

Rinne, Mikael

Thesis advisor

van der Weij, Oskar

Keywords

hard rock modelling, parking facility, tunnel, rock construction costs, 3dec, kgCO2e

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Citation

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-202408255773

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[dipl] Insinööritieteiden korkeakoulu / ENG