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Numerical analysis of the effects of grouting on mitigating the risk of hydraulically induced failure during deep shaft excavation
Šaponjić, Jovan
Divac, Dejan
Divac, Nikola
Radovanović, Slobodan
Abstract: Hydraulic failure presents a significant stability and safety issue for deep shaft excavation projects that deal with a high groundwater table in cohesionless soil. In urban environments, the lowering of the groundwater table for deep shaft excavations is usually not an acceptable solution to mitigate these risks due to the surface settlements it may cause, thus jeopardizing the safety of the surrounding structures. In this paper, a case study of an inlet shaft of a TBM-bored wastewater tunnel in Belgrade, Serbia was analyzed in order to show that grouting techniques can be an appropriate measure for reducing hydraulically induced instability. Since the location of the shaft is near the riverbank, the soil stratigraphy consists of granular soils with a high groundwater table. Several different variations of grout curtains around the shaft were modelled by conducting steady state flow analysis using commercial software based on the finite element method, and the obtained results were used to determine the risk of hydraulically induced failure at the bottom of the excavation. Based on the obtained results it is concluded that the application of grout curtains is a suitable solution for increasing the factor of safety for hydraulic heave problems as well as for soil failure problems. However, when encountering an aquitard layer during the earlier phases of excavation, grout curtains have no effect on lowering the pore pressures that are inducing the uplift at the bottom of the aquitard layer.
engleski
2023
Ovo delo je licencirano pod uslovima licence
Creative Commons CC BY-NC-ND 4.0 - Creative Commons Autorstvo - Nekomercijalno - Bez prerada 4.0 International License.
http://creativecommons.org/licenses/by-nc-nd/4.0/legalcode
10.1201/9781003348030-107