Controlling tunnel induced ground surface and pile movements using micropiles

Tunnelling in densely populated areas is generally associated with undesirable ground movement and subsequent damage to adjacent buildings. Hence, the main concern of designers are to accurately predict ground movements and propose mitigation measures in severe cases. Nowadays, different techniques...

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Main Author:	Sohaei, Houman
Format:	Thesis
Language:	English
Published:	2017
Subjects:	TA Engineering (General) Civil engineering (General)
Online Access:	http://eprints.utm.my/id/eprint/79121/1/HoumanSohaeiPFKA2017.pdf
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id	my-utm-ep.79121
record_format	uketd_dc
spelling	my-utm-ep.791212018-09-30T08:17:26Z Controlling tunnel induced ground surface and pile movements using micropiles 2017 Sohaei, Houman TA Engineering (General). Civil engineering (General) Tunnelling in densely populated areas is generally associated with undesirable ground movement and subsequent damage to adjacent buildings. Hence, the main concern of designers are to accurately predict ground movements and propose mitigation measures in severe cases. Nowadays, different techniques are used as a mitigation measure to reduce the impact of tunnel construction on ground settlement. Nevertheless, implementation of some of these methods is a source of unpredictable damage or undesirable effects such as the effect of installing micropiles between existing pile building foundation and tunnel which have yet to be understood. Hence, this research aims to establish a micropiles method as a mean to minimise ground surface settlement, and the settlement and lateral movement of the existing pile due to tunnelling through cohesionless soils. The study was carried out by means of laboratory physical model tests and numerical simulation using ABAQUS software. Three different relative densities of sand; 30%, 50%, and 75% were investigated while the overburden (cover to diameter) ratios used were 1, 2, and 3. A row of 3.7 mm diameter micropiles, dmp with two different lengths (11 cm and 14.5 cm) was embedded in between the tunnel (5 cm diameter, D) and the existing pile at four different locations. In model tests, settlement, bending moment and axial force of the existing pile were monitored accordingly. Generally, the results showed that increasing the value of relative density of sand reduces the ground movements. However, shallow tunnelling in loose sand produces remarkable movement on the ground surface. With the usage of micropiles, the ground surface settlement was reduced to nearly 40%. The micropiles also reduced over 85% and 75% of the piles lateral and axial movements respectively. A good compatibility was found between the experimental and numerical approaches which illustrates that the presented numerical simulation is a reliable model to predict tunnel-pile-soil and tunnel-pile-soil-micropiles interactions. Within the limitation of the study, it is recommended that the most suitable length and location of micropiles to use is 14.5 cm or about 40dmp (closest to the tunnel crown) and located at 0.5D (in the middle between tunnel and pile), based on the reduction observed on the vertical and lateral movements of pile as well as the bending moment and axial force. 2017 Thesis http://eprints.utm.my/id/eprint/79121/ http://eprints.utm.my/id/eprint/79121/1/HoumanSohaeiPFKA2017.pdf application/pdf en public phd doctoral Universiti Teknologi Malaysia, Faculty of Civil Engineering Faculty of Civil Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TA Engineering (General) Civil engineering (General)
spellingShingle	TA Engineering (General) Civil engineering (General) Sohaei, Houman Controlling tunnel induced ground surface and pile movements using micropiles
description	Tunnelling in densely populated areas is generally associated with undesirable ground movement and subsequent damage to adjacent buildings. Hence, the main concern of designers are to accurately predict ground movements and propose mitigation measures in severe cases. Nowadays, different techniques are used as a mitigation measure to reduce the impact of tunnel construction on ground settlement. Nevertheless, implementation of some of these methods is a source of unpredictable damage or undesirable effects such as the effect of installing micropiles between existing pile building foundation and tunnel which have yet to be understood. Hence, this research aims to establish a micropiles method as a mean to minimise ground surface settlement, and the settlement and lateral movement of the existing pile due to tunnelling through cohesionless soils. The study was carried out by means of laboratory physical model tests and numerical simulation using ABAQUS software. Three different relative densities of sand; 30%, 50%, and 75% were investigated while the overburden (cover to diameter) ratios used were 1, 2, and 3. A row of 3.7 mm diameter micropiles, dmp with two different lengths (11 cm and 14.5 cm) was embedded in between the tunnel (5 cm diameter, D) and the existing pile at four different locations. In model tests, settlement, bending moment and axial force of the existing pile were monitored accordingly. Generally, the results showed that increasing the value of relative density of sand reduces the ground movements. However, shallow tunnelling in loose sand produces remarkable movement on the ground surface. With the usage of micropiles, the ground surface settlement was reduced to nearly 40%. The micropiles also reduced over 85% and 75% of the piles lateral and axial movements respectively. A good compatibility was found between the experimental and numerical approaches which illustrates that the presented numerical simulation is a reliable model to predict tunnel-pile-soil and tunnel-pile-soil-micropiles interactions. Within the limitation of the study, it is recommended that the most suitable length and location of micropiles to use is 14.5 cm or about 40dmp (closest to the tunnel crown) and located at 0.5D (in the middle between tunnel and pile), based on the reduction observed on the vertical and lateral movements of pile as well as the bending moment and axial force.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Sohaei, Houman
author_facet	Sohaei, Houman
author_sort	Sohaei, Houman
title	Controlling tunnel induced ground surface and pile movements using micropiles
title_short	Controlling tunnel induced ground surface and pile movements using micropiles
title_full	Controlling tunnel induced ground surface and pile movements using micropiles
title_fullStr	Controlling tunnel induced ground surface and pile movements using micropiles
title_full_unstemmed	Controlling tunnel induced ground surface and pile movements using micropiles
title_sort	controlling tunnel induced ground surface and pile movements using micropiles
granting_institution	Universiti Teknologi Malaysia, Faculty of Civil Engineering
granting_department	Faculty of Civil Engineering
publishDate	2017
url	http://eprints.utm.my/id/eprint/79121/1/HoumanSohaeiPFKA2017.pdf
_version_	1747818151708459008

Controlling tunnel induced ground surface and pile movements using micropiles

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