Department of Civil Engineering
  1. Civil Engineering Structures
  2. Fluids Engineering Centre
  3. Multi-scale Geotechnical Engineering
  4. Temporary Works & Construction Method Engineering
Department of Civil Engineering

Research Centre for Multi-scale Geotechnical Engineering

Exploring novel solutions to geotechnical problems by linking micro-mechanics to the macro response.

Accurate and well-instrumented geotechnical centrifuge modelling is used to examine the behaviour of foundations and underground infrastructure in the crowded ground that typifies urban environments leading to novel design and construction processes. Insights into the macro response are provided by a combination of element testing and the use of sophisticated imaging techniques that study the behaviour of individual particles or agglomerations of particles rather than treating soil as a continuum.

People

ProfessorsSBBF244SC388SC353

  • Professor Sarah Stallebrass, Head of Department
  • Professor Neil Taylor
  • Senior Lecturers

    Lecturers

    Research FellowsSBBH121SBBJ820GOODEY

    Research (PhD) Students

    Projects

    Proposed

    Influence of new construction related to subway expansion

    Principal Investigator: Professor Neil Taylor

    Description: The expansion of subway stations can involve the construction of short lengths of new passageways, access points and lift shafts. This creates a complex soil-structure interaction problem with existing infrastructure which is difficult to quantify especially due to uncertainties of the relative stiffness of all components in the system. The problem can be investigated using careful physical models tested on the geotechnical centrifuge facility. This will allow the creation of a database of response behaviour that will allow designers to assess effectively the potential impacts of new construction.

    Development of necessary protective measures to control excavation induced ground movements

    Principal Investigator: Professor Neil Taylor

    Description: The development of underground transit systems often involves construction of short lengths of tunnels in the vicinity of other tunnels and excavations. Geometrical constraints can force the new tunnels to be in very close proximity to the existing excavations and special protective measures may be needed to control the spread of ground movements. This problem can be investigated using careful physical models tested on the geotechnical centrifuge facility which will give a clear insight into the relative effectiveness of different types of protective measures.

    Improving access to underground space

    Principal Investigator: Dr Sam Divall

    Description: The development of urban infrastructure often requires complex engineering solutions to access an underground space.  These structures often can take the form of concourse tunnels, passageways, shafts and launch portals which are often erected in areas where space is limited.  The construction processes involved in the creation of these structures often have a reasonably high level of uncertainty attached due to the complex soil to structure interaction taking place.  City, University of London’s geotechnical centrifuge facility allows for these construction processes to be investigated using well-controlled physical modelling techniques.  Model scale observations can be advantages in understanding the uncertainties at the prototype scale.

    Soil improvement construction techniques

    Principal Investigator: Dr Sam Divall

    Description: The development of urban infrastructure often requires complex engineering solutions in challenging soil conditions.  For example, tunnelling in weak stratums.  The construction processes currently utilised in the creation of these structures require the development of guidelines on their implantation which will enable engineers to predict the effectiveness or the potential impacts of the remedial works.  City, University of London’s geotechnical centrifuge facility allows for these construction processes to be investigated using well-controlled physical modelling techniques.  Model scale observations can be advantages in understanding the uncertainties at the prototype scale.

    Current

    Safety of Working Platforms for Tracked Plant Formed from Construction Demolition Waste

    Researcher: Greta Tanghetti

    Supervisor: Dr Richard Goodey

    Description: The key design criterion for working platform design is whether it can safely support the application of an extremely high monotonic load applied eccentrically through the tracks of plant. Thus, the design criterion is stability. The BRE guide idealises this load case as load acting over an equivalent area, rectangular in plan, which lies on layered ground. The depth of the upper layer, the working platform, is determined by assuming a punch through failure mechanism in this layer and conventional bearing capacity failure in the subgrade.  Designers following this method then need to determine the appropriate angle of friction to be used in the calculation of the resistance of the platform material (construction demolition waste) to punching failure.  The aim of this approach is to provide a conservative design method given that insufficient data exists.

    This research project is supported by The Centre of Excellence in Temporary Works and Construction Method Engineering and the Temporary Works Forum (TWf).

    Multiscale modelling of shelly carbonate sands for foundation design of offshore structures (MuMShell)

    Researcher: Dr Deqiong Kong

    Principal Investigator: Dr Joana Fonseca

    The proposed research uses 4D synchrotron x-ray imaging and post analysis to investigate the kinematics and the strain maps of a shelly carbonate sand under compression. The outcomes will contribute scientific understanding on the multiscale behaviour of shelly carbonate sands. This will form the basis to develop fabric-informed constitutive models to better predict the soil response, thus improving design practices for foundations of offshore structures.

    This project is EPSRC First Grant funded

    Interaction between new and existing underground infrastructure

    Researcher: Dr Sam Divall

    Principal Investigator: Dr Richard Goodey

    Description: Centrifuge modelling is being utilised to investigate the interaction between a shaft construction and an existing tunnel lining in clay. This project aims to understand how various spatial layouts of shaft impact on the tunnel lining.

    Outputs: Divall & Goodey (2016)
    Shaft

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    Minimising ground movements in soft soils adjacent to excavations

    Researcher: Jignasha Panchal

    Principal Investigator: Dr Andrew McNamara

    Description: Centrifuge modelling techniques will investigate methods of reducing ground movements in soft clays arising from deep excavations. This project will focus on feasible construction methods that can be implemented on site to reduce the effects of heave and subsequently mitigate movements behind the wall.
    softsoils

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    Multi-scale modelling and characterisation of granular media

    Researcher: Sadegh Nadimi

    Supervisor: Dr Joana Fonseca

    Description: The proposed research focuses on the investigation of the mechanical properties of granular materials across the scales. It includes the development of 3D image-based µFE modelling to simulate the grain-to-grain interactions under a variety of loading scenarios and compute the internal maps of strain and stresses. This will help establishing the link between the micro phenomena and the macro response and contribute towards improving geotechnical design.

    Outputs: Nadimi et al. (2015) and Nadimi et al. (2016)

    Granular materials models

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    Investigation into the primary fabric of stress transmitting particles in sand

    Principal Investigator: Dr Joana Fonseca

    Description: This study investigates the networks of stress transmitting particles based on the geometrical data obtained from micro-CT images. This study contributes with unique insights into the influence of contact and grain morphologies on the process of the stress transmission from grain-to-grain and consequently, on the deformation and macro-scale response of the material.

    Outputs: Fonseca et al. (2015)

    Diagrams showing the response of sand

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    Compensation grouting to control ground movements around deep excavations

    Researcher: Hitesh Halai

    Supervisor: Dr Andrew McNamara

    Description: The London Geotechnical Centrifuge is used to model compensation grouting behind a retained 12m deep excavation. The research study examines the effectiveness of the technique in controlling surface ground movements and the impact on the retaining wall during and after an excavation. The results could provide a better understanding of the limitations present when considering its use behind excavations.

    Successes

    The effect of soil reinforcement on tunnel face stability in clay

    Researcher: Binh Le

    Supervisor: Professor Neil Taylor

    Description: In weak or unstable ground conditions, tunnelling induced movements could be controlled by providing Forepoling Umbrella System ahead of the tunnel face. This research, through centrifuge modelling techniques, aims to obtain the key features affecting the efficiency.

    Outputs: Le & Taylor (2016) and Le et al. (2015)

    Diagram showing Forepoling Umbrella System

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    The disaggregation of soil during slurry tunnelling

    Researcher: Dr Neil Phillips

    Supervisor: Professor Sarah Stallebrass

    Description: The research project has designed a laboratory mixing test using a planetary mixer to aid in the prediction of the grading of excavated soil after transportation through the slurry pipeline. To aid in the disaggregation breakdown, soil classification tests were also carried out. Understanding the amount a soil disaggregates during transportation is key when specifying the separation plant.

    Microstructure evolution during cone penetration in silt (Collaboration with NTNU Trondheim, Norway)

    Principal Investigator: Dr Joana Fonseca

    Description: This project looks at the change in soil microstructure around the probe during cone penetration to investigate the failure mechanism and the processes controlling drainage in silt. It uses image analysis of backscattered electron (EPMA) images of polished thin sections prepared from frozen samples. Understanding the mechanisms of grain reorientation following cone penetration can help explaining the drainage patterns controlling the cone resistance and the development of pore pressures.

    Outputs: Paniagua et al. (2015)

    void contours

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    Ground movements associated with twin-tunnel construction in clay

    Researcher: Dr Sam Divall

    Supervisor: Dr Richard Goodey

    Description: Therefore, a series of plane strain centrifuge tests was carried out investigating twin tunnelling-induced settlements in overconsolidated clay. Apparatus necessary to perform these tasks required a significant amount of time to develop and was relatively complex. The main variables were the spacing between the tunnels, both horizontally and vertically, and the magnitude of volume loss. The tests were conducted at 100g where the cavities represented two 4m diameter tunnels at (usually) a depth of 10m at prototype scale. The tests utilised novel apparatus designed during the research to enable the simulation of the construction processes related to volume loss in separate sequential tunnels.

    Outputs: Divall & Goodey (2012) and Divall & Goodey (2015)

    Behaviour of ribbed piles in clay

    Researcher: Dr Rohit Gorasia

    Supervisor: Dr Andrew McNamara

    Description: This research concerns the influence of ribs on the ultimate capacity of a bored pile in overconsolidated clay. Ribbed bored piles are known to give increased shaft capacity in comparison to conventional straight shafted bored piles.  Experimental data were obtained from a series of 23 centrifuge model tests undertaken at 50g. The geometry of the model was such that it was possible to test two piles with each test. Of the two piles tested one was always a plain pile, this allowed for direct comparison to the ribbed pile in the same test and hence any inconsistency in the soil sample to be accounted for. The performance of several rib designs and spacings were investigated, whilst the pile inner diameter and length remained constant. A series of datum tests were conducted to verify the accuracy and repeatability of the testing equipment. Four rib types were tested; concentric ribs, helical ribs, tapered ribs and under reamed ribs. The use of ribs was found to always increase the ultimate capacity of a pile. Of all the rib profiles tested the helical profile was shown to be the most effective.

    Outputs: McNamara & Gorasia (2016)

    Facilities

    Engineering laboratory with centrifugeGeotechnical centrifuge at CityPurpose-built laboratory housing a recently refurbished Acutronic 661, 40 g-tonne, geotechnical centrifuge with state of the art instrumentation, image capture, and hydraulic, electrical and optical slip rings. The centrifuge facility is operated by a highly experienced team of researchers using actuators, motors and syringe pumps to carefully simulate geotechnical events in flight. It is accompanied by space for model preparation, including consolidation presses to create clay soil beds for testing and additional loading frames for 1g testing.

    Element testing laboratory containing automated stress path triaxial apparatus, shear box apparatus, a Bishop ring shear apparatus and a high pressure triaxial cell. This facility also provides space for classification tests and a range of customised tests investigating soil slurries, bentonite and the effect of adding polymer.

    Events

    Upcoming events

    • 17th - 20th July 2018 - 9th International Conference on Physical Modelling in Geotechnics (ICPMG 2018)
      (see www.ICPMG2018.London for more information)

    Past events

    Workshops

    • City/Cambridge: Physical Modelling in Geotechnics Workshop
    • City, University of London - BuroHappold Networking Event

    Seminars

    • Energy efficiency of building foundations used as heat exchangers by Dr Fleur Loveridge (University of Leeds)
    • Recent developments in offshore site investigations by Tim Carrington, Head of Geotechnical Services (Fugro GB Marine Limited)
    • Minimising ground movements around deep excavations in soft soils by Jignasha Panchal (City, University of London)
    • Experimental research on the consolidation behaviour of peat by Dr Daniel Barreto (Edinburgh Napier University)
    • Particle breakage under 1D compression using both experiments and numerical analysis by Lorenzo Di Pasquale (Universite Grenoble Alpes)
    • Effects of soil-structure interaction on seismic performance of piled foundations in liquefied soils by Dr Domenico Lombardi (The University of Manchester)
    • The Effect of Robust Fabrics in Natural and Reconstituted Soils by Prof Matthew Coop (City University of Hong Kong)
    • Soil-blast interactions by Dr Sam Clarke (University of Sheffield)
    • Sadegh Nadimi MPhil to PhD transfer presentation (City, University of London)
    • Monitoring and modelling the effects of climate and vegetation on clay earthworks by Dr Joel Smethurst (University of Southampton)
    • Deep and slow landslides in clay slopes triggered by slope-atmosphere interaction by Dr Giuseppe Pedone (University of Southampton)
    • The geotechnical implications of the 2010 - 2011 Christchurch Earthquake Sequence by Prof Michael Davies (University of Sussex)
    • A Study on Hydraulic State in River Dykes and Some Other Topics by Dr Nishimura (Hokkaido University)
    • Approaching small strain stiffness of soils: many challenges, some solutions by Dr Erdin Ibraim (University of Bristol)
    • The evolving role of the Geotechnical Engineer by Alex Nikolic (A-Squared Studio)
    • Performance-based design in geotechnical engineering by Prof Malcolm Bolton (Cambridge University)

    Find us

    City, University of London

    Northampton Square

    London EC1V 0HB

    United Kingdom

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    City, University of London is an independent member institution of the University of London. Established by Royal Charter in 1836, the University of London consists of 18 independent member institutions with outstanding global reputations and several prestigious central academic bodies and activities.