Publications
142 results found
Harris DI, Mair RJ, Burland JB, et al., 2017, The Big Ben Clock Tower: Protective compensation grouting operations, Geotechnics and Heritage: Historic Towers, Pages: 59-72, ISBN: 9781138032729
The construction of the Jubilee line Extension Station at Westminster, London was predicted to produce significant movements of the Big Ben Clock tower and the adjoining Palace ofWestminster. The works consisted of the excavation of two vertically stacked 7.4m tunnels and a 39m deep station escalator box respectively located 28m and 34m north of the foundations of the Clock Tower. The protective measures adopted to minimise damage to these priceless historic buildings consisted primarily of compensation grouting below the Clock Tower and proved extremely effective in controlling settlement and tilt of the structure. This case study not only demonstrates the success of this protective measure, but also shows the value of careful interpretation of appropriate numerical modelling and the results of high quality monitoring during and after completion of the works.
Standing JR, Lau C, 2017, Small-scale model for investigating tunnel lining deformations, Tunnels and Underground Space Technology, Vol: 68, Pages: 130-141, ISSN: 0886-7798
Tunnel linings in situ are rarely truly circular in form. Shapes depend on factors such as the nature of the lining, method of build, connections between segments, self-weight deformations and ground stresses. A small-scale two-dimensional simplified tunnel lining model comprising six segments was developed where the lining was loaded using a reaction ring. The results provide insight into factors that control the lining response: e.g. the deformed shape depends on the nature of the imposed loading, tightness of the bolts, number of segments and joint flexibility. This small-scale model was developed as a precursor to a sophisticated large-scale structural model used to assess the effect of tunnelling on existing tunnels (Yu et al., 2017). In this respect it proved very instructive, especially for assessing the method of loading the ring. An important message from the paper is how an inexpensive, but carefully thought out, small-scale model can provide great insight to the development of large-scale models that will involve orders of magnitude more time and expense. Many of the findings from the small-scale study were verified by the more realistic large-scale model which was able to provide details on deformations and stress changes in the segments and bolts.
Avgerinos V, Potts DM, Standing JR, et al., 2017, Predicting tunnelling-induced ground movements and interpreting field measurements using numerical analysis: Crossrail case study at Hyde Park, Géotechnique, Vol: 68, Pages: 31-49, ISSN: 0016-8505
Ground response to the construction of the Crossrail tunnels in London Clay beneath Hyde Park has been modelled numerically using advanced finite-element analyses. The soil model used for modelling the London Clay was a kinematic hardening soil model (named M2-SKH). This model, when used for the St James's Park greenfield site, provided excellent predictions of tunnelling-induced ground movements. Comparison of the results from the analysis of the Hyde Park greenfield site with associated field monitoring data also suggests excellent predictions, even though in this case the tunnels were: of larger diameter; deeper in the London Clay; and constructed with earth-pressure-balance machines. The influence of lining permeability was found to influence significantly short- and longer-term predictions. Interpretation of the predicted surface and subsurface vertical and horizontal displacements due to the construction of the Crossrail tunnels exemplifies how numerical analysis can assist in explaining and identifying potential ambiguities in field measurements.
Wan MSP, Standing JR, Potts DM, et al., 2017, Measured short-term ground surface response to EPBM tunnelling in London Clay, Géotechnique, Vol: 67, Pages: 420-445, ISSN: 0016-8505
Earth-pressure-balance machines (EPBMs) were used for the construction of Crossrail tunnels in London, providing opportunities for field investigation of consequent ground response. Analysed results from an instrumented research site in Hyde Park with extensive surface and subsurface monitoring arrays are presented and discussed. The Crossrail tunnels at the site are 34·5 m below ground, deeper than those in most case histories of tunnelling in stiff clay in the UK. This paper characterises the tunnelling-induced ground response, both ‘greenfield’ and in the proximity of the existing Central Line tunnels, dealing with measurements at the ground surface. A companion paper covers the subsurface ground response. Vertical and horizontal ground surface displacements were obtained from manual precise levelling and micrometer stick measurements. Several key findings will benefit future tunnelling projects involving EPBMs. Volume loss values measured at the instrumented site were low, being less than 0·8% and 1·4% for the first and second tunnel drives respectively, higher values being associated with ground softening from the first tunnel construction. Smaller volume losses were recorded in the vicinity of the existing Central Line tunnels, compared with the greenfield location, suggesting that their presence inhibited the development of ground movements. Asymmetric settlement troughs developed due to either the nearby pre-existing tunnels or the construction of the first tunnel. Marginally smaller values of trough width parameter, Ky, were determined for these deeper tunnels compared with previous greenfield ground case histories. Resultant vectors of ground surface displacement were directed to well-defined point-sinks above the tunnel axis level.
Afshan S, Yu JBY, Standing JR, et al., 2017, Ultimate capacity of a segmental grey cast iron tunnel lining ring subjected to large deformations, Tunnelling and Underground Space Technology, Vol: 64, Pages: 74-84, ISSN: 0886-7798
Understanding the behaviour of existing tunnels subjected to in-service deformations, as a result of the construction of underground works (e.g. new tunnels) in their proximity, is of importance in order to safeguard infrastructure within the urban environment. The associated deformations that take place during tunnelling have to be carefully assessed and their impact on the existing tunnels needs to be considered. A half-scale segmental grey cast iron (GCI) tunnel lining ring was tested as part of an extensive research project investigating the impact of new tunnel excavations on existing tunnels conducted at Imperial College London. A sophisticated experimental arrangement was developed to deform the ring in a variety of modes under combined displacement and load control. This paper reports on experiments carried out to assess its structural response when subjected to large deformations. The tests reported are the first to be conducted on a realistic scale model under carefully controlled conditions, and provide valuable insight into the behaviour of a GCI segmental ring during distortions commonly observed in reality. Details of the experiments, including the adopted test set-up and the instrumentation employed, are presented. The measured bending moments around the ring, as a result of the applied deformations, are determined and compared with those predicted using the well-known equations given by Morgan (1961) and Muir Wood (1975), often used in industry, as well as those obtained assuming an elastic continuous ring.
Cassar J, Standing JR, 2017, Geomaterials: aggregates, building stone and earthworks: papers from 50 years of QJEGH, QUARTERLY JOURNAL OF ENGINEERING GEOLOGY AND HYDROGEOLOGY, Vol: 50, Pages: 95-105, ISSN: 1470-9236
Numerous papers included within the broad subject of geomaterials have been published in QJEGH over the past 50 years. These have been compiled and divided here into three main categories: aggregates, building stone and earthworks. The aim of this review is to provide a comprehensive summary of the relevant papers published in QJEGH with a view to identifying the main areas of interest historically, now and in the future. Some clear trends are evident from the survey and review; for example, there has been a steady interest in building stone and in particular its deterioration, a decline in papers on earthworks and an increase in those on ground improvement (also covered here). It is also noted that methods of characterizing geomaterials are becoming more sophisticated with advancing technology. The review makes relevant links with other Special Publications from the Geological Society, including also Engineering Geology Special Publications.
Ko FWY, Standing JR, 2017, New risk method to assess tree interaction with structures, Proceedings of the ICE - Municipal Engineer, Vol: 170, Pages: 38-59, ISSN: 1751-7699
Ground and structural responses to presence of trees can be detrimental if their probable interactions are not duly considered. For example, trees growing in swelling/shrinking clays can lead to damage of buildings that are in close proximity. Very often the problem is not identified until appreciable damage has occurred. Guidelines relating to acceptable distances of trees to buildings are available, but these usually require specialist knowledge of trees. Current practices concerning tree protection and the subject of assessing potential structural damage from trees are reviewed and shortcomings are identified. Following this, two new risk methods to assess likelihood of damage to structures are explained. One covers damage occurring from direct growth of tree roots and the other is associated with settlement/heave above shrink/swell clay. Both systems are intended to provide a basis for identifying situations where advice by tree specialists should be sought, ideally in advance of occurrence of damage. The former was tested by field surveys at several locations in and around London and the latter by well-documented case studies. Both demonstrated that the systems have broad applications. This led to the development of a set of recommendations, in the form of an index chart, for planting trees close to structures.
Yu J, Standing J, Vollum R, et al., 2017, Experimental investigations of bolted segmental grey cast iron lining behaviour, Tunnelling and Underground Space Technology, Vol: 61, Pages: 161-178, ISSN: 0886-7798
The need for the research reported in this paper was driven by the Crossrail project in London for which new tunnels were constructed close to numerous existing operational tunnels of the London Underground (LU) network.This research is based on experimental work conducted on half-scale grey cast iron (GCI) tunnel lining segments with chemical composition similar to the Victorian age GCI segments in the LU network. This paper discusses the deformation behaviour of the bolted segmental lining under the influence of factors such as overburden pressure, bolt preload and presence of grommets at small distortions. The measured behaviour of the segmental lining is compared against the calculated response of a continuous lining based on the assumption of elasticity.The industry practice for tunnel lining assessment is to calculate the induced bending moment in the tunnel lining using an elastic continuum model, while adopting a reduced lining stiffness to take into account the presence of the joints. Case studies have recorded that both loosening and tightening of lining bolts have been used as mitigation measures to reduce the impact of new tunnel excavations on existing GCI tunnels.The experimental work on the half-scale GCI lining has shown that a bolted segmental lining behaves as a continuous ring under small distortions imposed when subjected to hoop forces relevant to the depth of burial of LU tunnels. In the presence of hoop force, joint opening was minimal and the magnitude of preload in the bolts had little impact on the behaviour of the lining. It is therefore concluded that disturbance of the bolts in existing tunnels is not recommended as a mitigation measure as in addition to being ineffective it is both time consuming and introduces the risk of damaging the tunnel lining flanges.
Mantikos V, Ackerley S, Kirkham AD, et al., 2016, Investigating soil-water retention characteristics at high suctions using Relative Humidity control, 3rd European Conference on Unsaturated Soils, Publisher: EDP Sciences, Pages: 10007-10007
A technique for controlling relative humidity (RH) is presented, which involves supplying a sealed chamber with a continuous flow of air at a computer-regulated RH. The desired value of RH is achieved by mixing dry and wet air at appropriate volumes and is measured for servo-control at three locations in the chamber with capacitive RH sensors and checked with a sensitive VAISALA sensor. The setup is capable of controlling RH steadily and continuously with a deviation of less than 0.2% RH. The technique was adopted to determine wetting soil-water retention curves (SWRC) of statically compacted London Clay, under both free-swelling and constant volume conditions. The RH within the chamber was increased in a step-wise fashion, with each step maintained until vapour equilibrium between the chamber atmosphere and the soil samples was established. Independent filter paper measurements further validate the method, while the obtained retention curves complement those available in the literature for lower ranges of suction.
Ackerley SK, Standing JR, Kamal RH, 2016, A system for measuring local radial strains in triaxial apparatus, Géotechnique, Vol: 66, Pages: 515-522, ISSN: 1751-7656
The importance of local measurement of small strains is well recognised. Without such measurements, accurate stiffness determination is not possible and can result in overestimations of strains resulting from stress changes in the ground. Axial strain is often considered to be the primary strain to be measured under triaxial conditions and there has been a focus on its measurement. Radial strain is also important, for example for determining Poisson's ratio and bulk modulus, or maintaining K0 conditions during consolidation. There are a number of devices available that enable its determination, using both direct and indirect measurement approaches. This note describes a system for measuring radial strains directly using linear variable differential transformers. It is shown to be simple, reliable, accurate and robust.
Avgerinos V, Potts DM, Standing JR, 2016, The use of kinematic hardening models for predicting tunnelling-induced ground movements in London Clay, Geotechnique: international journal of soil mechanics, Vol: 66, Pages: 106-120, ISSN: 0016-8505
The use of a kinematic hardening soil model for predicting short- and long-term ground movements due to tunnelling in London Clay is investigated. The model is calibrated against oedometer and triaxial tests on intact samples from different units of the London Clay. The calibrated model is then used in finite-element analysis to simulate the field response at St James's Park during excavation of the Jubilee Line Extension tunnels. The finite-element predictions compare well with the available field monitoring data. The importance of using consistent initial conditions for this complex boundary value problem in conjunction with the model parameters selected is highlighted. The stiffness response of different regions of the finite-element mesh indicates that the rate at which the stiffness degrades and the stiffness response further away from the tunnel boundary affect the short-term predictions significantly. The long-term predictions confirm that the compression characteristics of the soil control the magnitude of the consolidation settlements and its permeability the shape of the long-term settlement profiles.
Al Haj KMA, Standing JR, 2016, Soil water retention curves representing two tropical clay soils from Sudan, Geotechnique, Vol: 66, Pages: 71-84, ISSN: 1751-7656
Soil water retention curves (SWRCs) form an essential component of frameworks coupling the hydromechanical behaviour of unsaturated soils. The curves describe how suction changes with variables such as degree of saturation. SWRCs can be determined from incrementally drying initially saturated reconstituted samples to a final residual state, thus developing the primary drying curve (PDC). The primary wetting curve (PWC) is established from subsequent incremental wetting and is hysteretic compared with the PDC. SWRCs for two reconstituted, high-plasticity, tropical clays from Sudan have been determined using the filter paper technique, for which the maximum measurable suction is 30 MPa. At this suction the degree of saturation for both soils was greater than 40% and did not reduce much further on full drying under ambient laboratory conditions. Thus the primary SWRCs did not develop into the usual sigmoidal shape expected. The development of SWRCs under various subsequent cycles of wetting and drying are presented and discussed along with details concerning volumetric changes and cracking during drying. In order to investigate the uniqueness of the PDC and PWC and the effect of initial void ratio, SWRCs were determined for samples formed by dynamic and static compaction under different applied energy levels and also for intact samples. These were found to be located to the left of the PDC and often the PWC too.
Standing JR, Potts DM, Vollum R, et al., 2015, Investigating the effect of tunnelling on existing tunnels, Underground Design and Construction Conference, Publisher: IOM3, Pages: 301-312
A major research project investigating the effect of tunnelling on existing tunnels has beencompleted at Imperial College London. This subject is always of great concern during theplanning and execution of underground tunnelling works in the urban environment. Many citiesalready have extensive existing tunnel networks and so it is necessary to construct new tunnels ata level beneath them. The associated deformations that take place during tunnelling have to becarefully assessed and their impact on the existing tunnels estimated. Of particular concern is theserviceability of tunnels used for underground trains where the kinematic envelope must not beimpinged upon. The new Crossrail transport line under construction in London passes beneathnumerous tunnels including a number of those forming part of the London Underground network
Yu J, Standing J, Vollum R, et al., 2015, Stress and Strain monitoring at Tottenham Court Road Station, London, UK, Proceedings of the ICE - Structures and Buildings, Pages: 107-117, ISSN: 0965-0911
The redevelopment of Tottenham Court Road Underground Station started in 2011 as part of the Tube Upgrade Plan to improve and increase the capacity of the existing facility. The plan is to upgrade the station by 2016 to meet an estimated demand of more than 200,000 journeys per day once Crossrail is built. During April to November 2011, major structural work was carried out on the Northern Line platform tunnels as part of the station upgrade. This included removing grey cast iron tunnellining segments on the platform side to allow for construction of new cross passages to improve access to the platforms. The upgrade works provided an opportunity to trial in-tunnel instrumentation prior to implementation in other London Underground (LUL) tunnels which interface with the Crossrail project. Mechanical and electrical resistance strain gauges were installed on tunnel segments to make discrete measurements of changes in strain due to unloading as the segments were removed from the tunnel rings. Linear variable differential transformer type displacement transducers were installed to make continuous measurements of the opening and closing of circumferential and longitudinal joints on trackside segments which are left insitu and affected by adjacent excavations. This paper describes the installation process and highlights the lessons learnt for future applications. The insitu strain measurements are presented and compared to the expected response based on laboratory tests conducted on grey cast iron tunnel segments in the 1970s. The changes in strain measured by both types of strain gauges agreed well with the estimated changes assuming full overburden unloading.
Standing JR, Potts DM, Vollum R, et al., 2015, Research into the effect of tunnelling on existing tunnels, Pages: 515-520
Increasing demands for providing transport systems in the urban environment has led to many tunnelling projects being undertaken worldwide. Many of the cities where new tunnels are to be constructed already have a comprehensive underground network of tunnels for both transport and services. New tunnels often have to be aligned beneath these and frequently there are concerns that their construction may cause unacceptable deformations of Ibe existing tunnels, potentially hindering their serviceability and in the extreme threatening their stability. The Crossrail project, currently underway in London, involves tunnelling beneath numerous existing tunnels. It therefore has provided a great opportunity to study this complex boundary value problem. This paper describes the philosophy behind a comprehensive research project, run in conjunction with the Crossrail construction, which has an emphasis on the response of older tunnels lined with grey cast iron segments. There is a focus on how the Central Line tunnels responded to new twin tunnel construction beneath them. The five main strands of the research arc: field monitoring within and around the existing tunnels; numerical analyses of the field conditions; structural testing of a half-scale grey cast iron segmental ring; numerical analyses of the ring and two-segment tests performed; advanced laboratory testing of London Clay samples taken during installation of field instrumentation. These activities link into each other. Some preliminary results are presented and the main finding to date arc summarised.
Al Haj KMA, Standing JR, 2015, Mechanical properties of two expansive clay soils from Sudan, GEOTECHNIQUE, Vol: 65, Pages: 258-273, ISSN: 0016-8505
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- Citations: 11
Yu J, Standing JR, Potts DM, et al., 2015, Tunnelling induced strains and deformations at Central Line, Crossrail Project infrastructure design and construction, Publisher: ICE Publishing, Pages: 499-518
Yu J, Potts DM, Standing JR, et al., 2015, In situ stress strain measurement at Tottenham Court Road platform tunnel, Crossrail Project infrastructure design and construction, Publisher: ICE Publiahing, Pages: 271-288
Wan MSP, Standing JR, 2014, Field measurement by fully grouted vibrating wire piezometers, PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-GEOTECHNICAL ENGINEERING, Vol: 167, Pages: 547-564, ISSN: 1353-2618
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- Citations: 13
Wang Y, Huang K, Cao Z, et al., 2014, Bayesian identification of soil strata in London Clay, GEOTECHNIQUE, Vol: 64, Pages: 1014-1016, ISSN: 0016-8505
Wan MSP, Standing JR, 2014, Lessons learnt from installation of field instrumentation, PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-GEOTECHNICAL ENGINEERING, Vol: 167, Pages: 491-506, ISSN: 1353-2618
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- Citations: 15
Choy CK, Standing JR, Mair RJ, 2014, Centrifuge Modelling of Diaphragm Wall Construction Adjacent to Piled Foundations, GEOTECHNICAL TESTING JOURNAL, Vol: 37, ISSN: 0149-6115
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- Citations: 2
Fearnhead N, Maniscalco K, Standing JR, et al., 2014, Deep excavations: monitoring mechanisms of ground displacement, PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-GEOTECHNICAL ENGINEERING, Vol: 167, Pages: 117-129, ISSN: 1353-2618
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- Citations: 12
Fong FHY, Standing JR, Bourne-Webb PJ, 2014, Building response to adjacent deep basement construction, PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-GEOTECHNICAL ENGINEERING, Vol: 167, Pages: 130-143, ISSN: 1353-2618
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- Citations: 4
Standing JR, Selemetas D, Shirlaw JN, 2014, Greenfield ground response to EPBM tunnelling in London Clay, GEOTECHNIQUE, Vol: 64, Pages: 581-583, ISSN: 0016-8505
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- Citations: 2
Hauswirth D, Puzrin AM, Carrera A, et al., 2014, Use of fibre-optic sensors for simple assessment of ground surface displacements during tunnelling, GEOTECHNIQUE, Vol: 64, Pages: 837-842, ISSN: 0016-8505
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- Citations: 34
Rimoy S, Jardine RJ, Standing JR, 2013, Displacement response to axial cycling of driven piles in sand, 18th Int. Conf. on Soil Mechanics and Geotchnical Engineering, Publisher: Presses des Ponts, Pages: 2387-2390
Standing JR, Selemetas D, 2013, Greenfield ground response to EPBM tunnelling in London Clay, Geotechnique, Vol: 63, Pages: 989-1007, ISSN: 0016-8505
Rimoy SP, Jardine RJ, Standing JR, 2013, Displacement response to axial cycling of piles driven in sand, ICE Proceedings Geotechnical Engineering
Standing JR, Ghail RC, Coyne DL, 2013, Gas generation and accumulation by aquifer drawdown and recharge in the London Basin, Quarterly Journal of Engineering Geology and Hydrogeology, Vol: 46, Pages: 293-302
Air at high pressure has recently been encountered during ground investigation borehole drilling for the Thames Tideway project in London. The air was released from within the Upnor Formation (at the base of the Lambeth Group beds), which is at the top of the Lower Aquifer. Cavitation within the granular beds of the Lower Aquifer would have occurred as a consequence of drawdown from the extensive water extraction that began at the start of the nineteenth century, resulting in the water table dropping by almost 70 m below ground level. Estimated historic pore pressure profiles are postulated and the cavitation process that occurred, along with the subsequent pressurisation of the air during recharge that has occurred in recent years, is discussed using behavioural concepts from unsaturated soil mechanics. The hypotheses are corroborated by a series of simple column experiments where the processes are modelled using analogous soils. Engineering implications of the presence of the pressurised air are discussed: besides the potential for borehole blow-out, another serious consideration is the depletion of oxygen from the trapped air by chemical reaction with the soil, increasing the risk of confined space hypoxia.
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