GEOTECHNICAL SOCIETY OF

IRELAND NEWSLETTER

WINTER 2014

Editor’s Note

Welcome to the latest edition of the Geotechnical Society of Ireland (GSI) newsletter. The purpose of this newsletter is to provide the geotechnical engineering community throughout Ireland with an up-to-date source of geotechnical news and to provide details of upcoming events.

If you are aware of a project of interest, recent research output or an upcoming event which you would like included in the next edition of the newsletter, please contact Maurice Ryan (mryan@blpge.com). All contributions would be greatly appreciated.

The GSI Committee

The GSI activities and events are organised and managed by a committee of geotechnical engineers working in Irish industry and academia. As this is the first edition of the newsletter since 2012, a brief introduction to the committee members is included below. If you are interested in taking a more active role in GSI events or joining the committee, please contact a committee member.

Fintan Buggy – ROD (Chairman)

Paul Quigley – ARUP (Secretary)

Michael Robinson – Test Consult

(Treasurer)

Maurice Ryan – Byrne Looby Partners

(Public Relations Officer)

Brian Byrne – Carlow IT

Ciaran Reilly – JB Barry

Cormac Reale – UCD

David Gill – AGL

Derek Luby – SLR Consulting

Gerry Stanley – Geological Survey of

Ireland

Kevin Flynn – AGL

Mark Condron – RPS

Paul Doherty - GDG

Paul Quigley – IGSL

Upcoming Events:

This upcoming season proves to be an

exciting and interesting year for

geotechnical events and conferences. The

table below details the upcoming events

of interest. Of particular note are the joint

GSI and IAH evening lecture and the GSI

half day seminar to be held during April

2015, both of which are free to attend and

usually present interesting topics of

practical significance.

Date Description Venue

GSI Events

February 2015 Joint GSI / IAH Evening Lecture

Engineers Ireland, 22 Clyde Road

Thursday 23rd April 2015

GSI Half Day Seminar Prof. Eduardo Alonso

Engineers Ireland, 22 Clyde Road

International Conferences / Events

10th December 2014

Fleming Award Evening

ICE, London

14th January 2015

John Mitchell Award Evening

ICE, London

18th March 2015

55th Rankine Lecture

Imperial College, London

13 – 17th September 2015

XVI European Conference on Soil Mechanics and Geotechnical Engineering

Edinburgh

TBC European Young Geotechnical Engineers Conference

Durham, UK

Please note that these dates are provisional –

please check for updates prior to event.

Coming Soon GSI Half Day Seminar

The upcoming GSI Half Day Seminar

promises to build on the success of the

inaugural event held in 2014. The GSI

Committee have secured Prof. Eduardo

Alonso of the University of Catalunya,

Barcelona as the keynote speaker, with

Prof. Alonso presenting a lecture on the

topic of Rapid Landslides.

Landslide displacements and velocity in

nature are often moderate, but known

cases of high velocity (>10 m/s) have

attracted considerable attention following

some extremely destructive cases in the

past.

The lecture shall cover topics including the

derivation of practical criteria to estimate

the risk of rapid slide acceleration, the

scale effects and the relationship between

the triggering of a rapid landslide and pre-

existent creep-like motions.

Further details on Prof. Alonso’s lecture

and the other topics to be covered during

the seminar shall be circulated closer to

the event.

Recent Events and Awards Civil Engineering Research Association in Ireland Conference

The Civil Engineering Research Association

of Ireland (CERAI) was established in 2012

arising out of a desire to broaden the

scope of the already successful Bridge and

Concrete Research in Ireland (BCRI)

conference series. The Association’s first

Civil Engineering Research in Ireland

(CERI) conference was recently hosted to

a very high standard by Queen’s

University Belfast. One of the highlights of

the two day event was an exquisite

conference banquet in Belfast City Hall.

Over 80 papers were presented covering a

diverse range of civil engineering topics.

The geotechnical keynote lecture was

given by Prof. Bob Gilbert of The

University of Texas at Austin and was

entitled “Opportunities for Innovation in

Offshore Geotechnical Engineering”.

There were 12 geotechnical papers

presented at the conference, with the

award for Best Paper going to Ciaran Reilly

and Trevor Orr for their paper “A novel

triaxial testing procedure to model the

action of lubricants in pipe jacking” and

Best Student Paper in Geotechnics to Luke

Prendergast, Ken Gavin and Paul Doherty

for their paper "The effect of scour on the

dynamic response of an offshore wind

turbine".

The Proceedings will be available for

download from www.cerai.net. The next

CERI conference will be held in Galway in

2016.

23rd European Young Geotechnical Engineers Conference

In September 2014 Brian Sheil and Martin

Timoney, both from NUI Galway,

represented Ireland at the 23rd European

Young Geotechnical Engineers Conference

(EYGEC) held in Barcelona, Spain.

Nearly 50 delegates, both researchers

and practitioners, from across Europe

attended the conference presenting on a

variety of geotechnical themes.

Conference Delegation

The papers presented covered a wide

range of topics including piling,

tunnelling, ground improvement,

numerical modelling, rock stability,

geothermal applications and

geotechnical risk management, with

results from laboratory experiments,

numerical analysis and field projects

presented.

Congratulations to Audrey Hucket

(France) on winning the best overall paper

for her experimental and numerical work

on the design of geosynthetic

reinforcements overlying sinkholes. The

proceedings for the conference have

been made freely available to download

from EYGEC Proceedings 2014.

Finally, the Irish delegates are very

grateful to GSI for providing them with the

opportunity to attend and present at the

conference.

Irish Delegates:

Brian Sheil, NUI Galway; Multi-directional

loading of a monopile foundation: finite

element modelling.

Martin Timoney, NUI Galway; Strength

verification of soil-cement columns; a

scale laboratory investigation of the Push-

In Resistance Test.

Congratulations

Geotechnical Engineer Sean Mason FIEI,

Director of ground and maritime

engineering at Arup Ireland, was awarded

Best Paper/Presentation at the Engineers

Ireland Excellence Award 2014. Sean’s

paper, entitled ‘Greystones Harbour – Civil

and Maritime Works’ was presented at

Engineers Ireland headquarters, and

subsequently due to popular demand at

the Royal Dun Laoghaire Yacht Club. The

paper provides an overview of the project

from bid stage through planning and

design to construction completion.

Geotechnical challenges and opportunities

are covered, including keeping an old

landfill within the site, managing

settlements of precast concrete block

breakwaters, value-engineering the site by

operating a borrow pit within the site to

maximise re-use of dredged materials,

and the state-of-the-art use of beach

nourishment to manage coastal erosion.

Greystones Harbour Congratulations also to Dr David Gill of

AGL Consulting, who was also one of only

three shortlisted for the award for his

paper entitled ‘Geotechnical Properties of

the Dublin Port Clay’, on behalf of the

Geotechnical Society.

Information and Useful Resources

ISSMGE Bulletin The International Society for Soil

Mechanics and Geotechnical Engineering

(ISSMGE) is the pre-eminent professional

body representing the interests and

activities of Engineers, Academics and

Contractors worldwide that actively

participate in geotechnical engineering.

The ISSMGE provides useful information

and platforms for the discussion and

review of various geotechnical related

items. The ISSMGE recently published its’

bimonthly bulletin which is available for

download from

ISSMGE_Bulletin_October_2014.

ISSMGE Technical Committees In order to engage ISSMGE members

across the array of geotechnical subjects,

the ISSMGE has set up various Technical

Committees to facilitate debate and

discussion.

The mission of the ISSMGE TCs is to

provide a forum for active participation by

the individual members of ISSMGE, and to

promote the objectives, activities and

results of the technical committees

throughout the ISSMGE membership. The

TCs are a meeting arena for discussing,

developing and applying specialist

geotechnical knowledge related to the

behaviour of geo-materials, geotechnical

engineering and engineering for society. A

list of the technical committees is

available at ISSMGE Technical

Committees.

The following GSI members hold active

positions on several ISSMGE TCs. Should

any other members wish to engage with

the technical committees please contact

Fintan Buggy (Fintan.Buggy@rod.ie).

Name ISSMGE TC Membership

Bryan McCabe

TC306 – Geo-Engineering Education

Fintan Buggy

TC202 – Transportation Geotechnics

Mike Long

TC102 – Ground Property Characterisation from In-Situ Tests TC214 - Foundation Engineering for Difficult Soft Soil Conditions

Declan Philips

TC306 – Geo-Engineering Education

Kenneth Gavin

TC209 - Offshore Geotechnics TC212 - Deep Foundations

Trevor Orr

TC205 - Safety and serviceability in geotechnical design

Case Studies and Interesting

Projects

River Dargle Flood Defence Scheme –

Works at La Vallee Bray

Works are nearing completion on a section of the River Dargle Flood Defence Scheme at the La Vallee complex in Bray. This project involved the construction of new flood defence and erosion protection walls along the banks of the Dargle over a 300m long section of the river channel, and the placement of a 1.4 m deep layer of rock armour along the bed of the river to protect against scour. The works were required to arrest the deterioration of the existing rock armour revetment along the left bank of the river, in front of the apartments and office building in the La Vallee complex, and to upgrade the existing erosion protection measures along the right bank of the river. The works were also required to re-profile the river channel to regulate river flows under extreme flood conditions and to reduce the high flow velocities to an acceptable level.

Installation of Tie-back Anchors The scheme is a Design and Build contract and is currently being constructed by Jons Civil Engineering Company Ltd. AGL Consulting are the principal designers and

geotechnical engineers for the scheme. Structural and hydrological designs were provided by O’Shea Consulting and Fluvio R&D respectively. The Employer is Wicklow County Council (formerly Bray Town Council) and Halcrow Barry are the Employer’s Representatives. The project is funded by the Office of Public Works for Wicklow County Council. The sheetpile retaining wall along the left bank is 300 m long, including the transition zones at either end. The design of the wall was governed by the requirement to excavate up to 1.4 m below design river bed level in the temporary condition with 4 storey office and residential buildings within close proximity to the wall. The retained heights ranged from 6.25 m–7.5 m. A total of 118 No. ground anchors ranging in length from 13.5-17.0m were installed at 2.4 m centres at 40° to the horizontal along the wall to provide lateral support in the temporary and permanent condition. The depth of the sheetpiles was governed by hard driving into weak weathered rock under strict controls for noise and vibration. In some places the sheetpiles did not achieve the required depth of toe penetration and temporary props were required at bed level to complete the dig for the scour protection. Sheetpiles were also installed along the right bank over a distance of 290 m along the river channel. The majority of the sheetpiles were constructed as a cantilever wall for a temporary retained height of 3.4 m to support the banks for the dig to install the scour protection. A 75 m section of the wall cut into the toe of a previous landslide on the right bank so the sheetpiles along this section of the wall were driven to rock at a depth of about 9.0 m and the wall was supported

by 22 No. 18.0 m long ground anchors which were installed at 3.6 m centres along the wall at 45° to the horizontal to provide a 5.0 m socket in rock. All of the design and construction work was completed within an extremely tight programme to complete the work in the river channel between the second week of July and the first week of November, with a project specific derogation from Inland Fisheries Ireland to work beyond the end of September. This posed many logistical constraints to coordinate all of the machinery and equipment within a narrow river channel which was prone to rapid flooding during periods of heavy rain. The project is now very close to completion with all works in the river bed completed and final landscaping underway.

Works Nearing Completion – Oct 2014

Dr Breiffni Fitzgerald (AGL Consulting)

Geotechnical Inspections in Dhaka,

Bangladesh

On 24 April 2013, Rana Plaza, an eight-story commercial building, collapsed in Savar, a sub-district in the Greater Dhaka Area, the capital of Bangladesh. The search for the dead ended on 13 May with a death toll of 1,129. Approximately 2,515 injured people were rescued from the building alive. It is considered the deadliest garment-factory accident in history, as well as the deadliest accidental structural failure in modern human history.

The building contained clothing factories, a bank, apartments, and several other shops. The shops and the bank on the lower floors immediately closed after cracks were discovered in the building. Warnings to avoid using the building after cracks appeared the day before had been ignored. Garment workers were ordered to return the following day and the building collapsed during the morning rush-hour.

Following this devastating collapse an independent legally binding agreement (The Accord) was designed to make all garment factories in Bangladesh safe workplaces. To date this Accord has been signed by over 150 apparel corporations from 20 countries worldwide. Arup was approached to conduct 1,500 structural surveys with Arup Ireland leading the project.

Main Objective

The objective of the project was to help ensure that there was no repeat of the Rana Plaza collapse. Arup developed a methodology that:

1. Classified the buildings according to perceived risk of structural failure,

2. Gave recommendations as to immediate and longer term actions to be implemented in the factories to reduce the risk, and

3. Could be applied to a large number of buildings over a short period of time.

The inspectors used Arup Inspect, an iPad App developed by Arup, to record on-site information. The app allows users to develop project specific templates while spatially recording photos and observations on building plans, documents or images. All the information was spatial recorded in GIS to allow for categorisation of areas and factories.

Typical Screenshot of Arup Inspect

Arup’s methodology has been adopted nationally in the country’s 5000+ factories and will also be applied in other developing countries such as India and Cambodia with similar building control and safety concerns. The project was also nominated as one of the Engineers Ireland Projects of the Year for 2014.

One of the first aspects of this project was a study into the ground conditions and geology of the capital Dhaka.

Geology of Dhaka, Bangladesh

Bangladesh is one of the world’s largest deltaic countries and is formed at the confluence of the Brahmaputra, Ganges and Meghna rivers. More than 85% of the landmass is flat alluvial floodplains, criss-crossed by the rivers and their numerous tributaries, with the exception of slightly elevated uplands in the central and north-western parts of the country.

Dhaka is situated in the central part of the country at the southern tip of the Madhupur Tract, an area of recent uplift, dating back to the Pleistocene age. The tract is surrounded by the new and old floodplains of the Brahmaputra to the west and east respectively and the Ganges to the south. These floodplains are still experiencing high rates of sediment transport from the Himalayas during monsoon season, continually adding to the Holocene fluvial deposits.

The elevated tract consists of older sediments hosting the major parts of Dhaka and is surrounded by very recent alluvial and estuarine sediments. The older sediment sequence consists of fine sand of the Dupi Tila Formation overlain by stiff clay classified as Madhupur Clay.

Ground Conditions

Within Dhaka, investigations showed a firm to stiff overconsolidated silty clay with a high plasticity and typical ranges of 5-20 SPT values, generally increasing with depth. This layer can vary in thickness from 6 – 12m. The clay layer is under lain by clean, on occasion silty, sand with SPT values greater than 25.

Reports from Narayanganj, southeast of Dhaka, show the geological change as we move away from the Madhupur Tract and into the floodplains of the Meghna River. Due to the fluvial deposits in this low-lying area, the recommendation of deep foundations was relatively unchanging. Investigations show silt content averaging around 70% and SPT value rarely rising above 10 for 12-15m below ground level.

Ground conditions are quite favourable in the central elevated areas of Dhaka. However, factors such as swelling clays in high areas, ground subsidence in depressions of saturated soils and the increase in soft clays along stream beds toward the eastern side of the city, create poor even hazardous ground conditions.

Ground in low-lying floodplains surrounding Dhaka is quite hazardous for building. To escalate the issue, reclamation of these areas using river bed material has been ongoing for some time. Loading from this fill will lead to settlement of the underlying soft soil. It’s also worth noting that these soft ground areas are highly susceptible to

liquefaction under dynamic loading, as Dhaka is set in Seismic Zone II.

Dhaka has a population density of 45,000 per square km within the city area, nearly 75 percent more dense than Hong Kong. With no proper waste disposal facilities available, waste is dumped on the roadsides and in open space. An estimated 60% of waste is left uncollected. Investigation logs on occasion showed 1.5-2m of municipal waste, with evidence suggesting that this material is being used as a reclamation material in soft ground areas in the west and east of the city.

Foundation inspections

As part of the initial assessment a review of the foundation drawings was undertaken. Comparisons between the foundations and recommendations in the ground investigation report were noted. Some typical issues included pile foundations advised but not installed. Sometimes the depth of the spread foundation were higher than specified.

The foundation type and nature was entered into the Arup Inspect app including any discrepancies between design and construction information. The data was uploaded to the risk assessment for the building. The final report issued to the owner was developed very quickly using the Arup Inspect app, including recommendations for further intrusive work, if necessary.

Cathal Mac an tSearraigh (Arup Ireland)

Canada House, St. Stephens Green, Dublin

Byrne Looby recently completed the detailed design of the embedded secant pile retaining wall to accommodate the 8m deep basement for this new office development at the corner of Dublin’s St. Stephens Green.

Basement Construction Underway

The city centre location, on the corner of

Earlsfort Terrace and St. Stephens Green,

required that our design meet tight

deflection constraints due to the site’s

close proximity to adjacent multi-storey

office buildings and neighbouring

properties. In addition due to the

restricted space available on site for the

proposed development, we were required

to limit our pile sizes wherever possible in

order to provide the largest basement

footprint achievable. As a result the pile

sizes varied between 900mm, 1200mm

and 1500mm diameter depending on the

installation location around the perimeter

of the basement.

The piles were installed by Murphy

International, using their powerful Bauer

BG 28 rotary rig. Extremely strong

limestone bedrock was encountered on

site, close to the proposed basement

formation level of 8.0m bgl, resulting in all

piles being socketed between 2 to 3m into

the underlying rock.

Due to the deflection constraints, a high

level propping system was required, with

the main contractor M.B. McNamara

Construction Ltd engaging Hegarty

Demolition to install a series of

Groundforce proprietary cross props to

restrain the pile wall at ground level.

The basement excavation is almost

complete, with the construction of the

basement slab and internal walls and

columns progressing.

The design services provided by Byrne

Looby, in conjunction with the flexibility in

pile sizes offered by Murphy International

and the powerful rock drilling capabilities,

ensured that a robust yet efficient

solution was provided.

High Level Propping System

Maurice Ryan (Byrne Looby Partners)

Open-faced Pipe Jacking beneath the

Royal Canal in Leixlip

In June this year, Newry-based Terra

Solutions Ltd. installed 60m of 1500mm

internal diameter wastewater pipeline by

pipe jacking under the Royal Canal and the

Dublin-Sligo railway line at Leixlip, Co.

Kildare. This crossing was part of the

North Leixlip Sewerage Scheme which was

designed by Tobin Consulting Engineers

on behalf of Irish Water.

Tunnelling Works Underway

The site investigation for the scheme

showed that the pipe jack alignment was

within strong to very strong Dinantian

Upper Impure Limestone, commonly

known as "Calp". Following examination

of the site investigation data, it was

decided to utilise an open-face pipe

jacking shield rather than the closed-faced

systems commonly employed for this type

of project. Observations of groundwater

levels and the condition of the bedrock

gave confidence that the pipe jack could

be completed without encountering

significant inflows of groundwater.

The successful operation of the open-face

pipe jacking shield allowed the project to

be completed in 9 days and with a

minimal site footprint and minimal

difficulties in disposing of the tunnelling

arisings, which were dry crushed

limestone.

The project showed that the use of more

traditional, non-automated, trenchless

construction techniques is still very

worthwhile given the correct ground

conditions and appropriately skilled

personnel.

Barry McAllister (Terra Solutions Ltd.)