Geotechnics of soft soils focus on ground improvement

Natural soft soils are very complex materials. As construction activities increasingly take place in poor ground conditions, ground improvement is often required. However, design practices for ground improvement were for long at best crude and conservative, and at worst unsafe. Although new construction and field observation techniques have been developed to ensure that geotechnical structures such as embankments, tunnels and deep excavations can be built safely under these difficult conditions, design is still predominantly based on empirical rules and simplifying assumptions.

Since 2000 increased computer power has made systematic numerical studies utilising the 3D finite element method more and more possible. This enabled the investigation of complex soil-structure interaction mechanisms associated with ground improvement problems. The EC-funded Research Training Network âe~Soft Clay Modelling for Engineering Practicenbsp;(SCMEP), was set up to develop improved constitutive and numerical models to assist in geotechnical design on soft clays, and made significant advances in theory backed up with substantial experimental programmes (2000-2004). The EC-funded Marie Curie Research Training Network AMGISS (Advanced Modelling of Ground Improvement on Soft Soils) continued the research by the SCMEP network, focussing on modelling ground improvement systems. The aim of the AMGISS network is to develop advanced numerical modelling techniques for analysing the coupled hydro-mechanical behaviour of ground improvement systems on soft soils utilising advanced constitutive modelling, physical modelling and 2D, enhanced 2D and 3D numerical modelling techniques.

The motivation of the 2nd International Workshop on Geotechnics of Soft Soils, organised by the AMGISS network (3-5 September 2008, Glasgow, Scotland), was to bring together practitioners and academics to discuss recent developments in soft soil modelling, focussing on ground improvement. This volume is a collection of papers from the workshop, and discusses the state-of-the-art in soft soil modelling and design, with particular emphasis on ground improvement applications, involving contibutions both from academia and industry. The topics included cover: Modelling (constitutive modelling, numerical modelling, and physical modelling), Design and Application (focusing mainly on embankments and foundations), and Ground Improvement (preloading and consolidation methods, column methods, piles and micropiles, and other ground improvement methods).

Geotechnics of Soft Soils - Focus on Ground Improvement will prove to be invaluable to research students, academics and practitioners, working in geotechnical design on soft soils.

M. Arnold and I. Herle and J. WherC.J. Dykstra and F.A.J.M. Mathijssen and F. MolenkampD. Egan and W. Scott and B. McCabeG. Gottardi and L. Cavallari and M. MarchiB. Indraratna and C. Rujikiatkamjorn and A. GhandeharioonL. Laloui and S. ChalindarT. Nakai and F. Zhang and H. Kyokawa and M. Kikumoto and H.M. ShahinM. Olsson and T. Edstam and C. AlénJ.F. Rodríguez and N.P. López-Acosta and G. AuvinetY. Yuan and L. Beuth and P.A. VermeerJ.L. BorgesP.M. Bujulu and G. Grimstad and S. Nordal and L.O. GrandeG. Di Fonzo and A. Flora and M.V. Nicotera and G. Manfredi and A. ProtaH.K. Engin and E.G. Septanika and R.B.J. Brinkgreve and P.G. BonnierM. Gäb and H.F. Schweiger and D. Kamrat-Pietraszewska and M. KarstunenJ. Gniel and A. BouazzaM. Kikumoto and T. Nakai and H. Kyokawa and F. Zhang and H.M. ShahinH. Krenn and M. KarstunenM. Leoni and P. Vermeer and M. KarstunenT. Stapelfeldt and P. Vepsäläinen and Z.-Y. YinR. van der MeijU. Vogler and M. KarstunenA. Yildiz and M. KarstunenC.-M. Chan and K.A. IbrahimA. Cimentada and A. Da CostaA. Demir and M. Ornek and M. Laman and A. Yildiz and G. MisirM.M. Hassan and O. RavaskaI. Herle and J. Wehr and M. ArnoldF. KirschA. Le Kouby and S. Guédon and I. PetkovskiI.P. Marzano and A. Al-Tabbaa and M. GrisoliaK. McGinty and M. Karstunen and S.J. WheelerC. Meier and C. Boley and Y. ZouJ.S. Melton and R.A. PrietoE.J. Pooley and S.M. Springman and J. Laue and J. NajserC. Rujikiatkamjorn and A. Ghandeharioon and B. IndraratnaC.J. Serridge and R.W. SarsbyD. Takano and J. Otani and T. MukunokiT.M. Weber and S.M. Springman and M. Gäb and V. Racansky and H.F. SchweigerC. Yu and L.Y. Pan and S.Y. Liu and G.Y. DuM. Bouassida and S. Ellouze and L. HazzarM. Bouassida and L. Hazzar and P. de BuhanJ. Castro and C. SagasetaC.J. Currie and M. MackayN. Harata and J. Otani and H. Ochiai and K. Onda and Y. OkudaS. Satibi and M. Leoni and P.A. Vermeer and R. van der MeijW. SteinerV. Berengo and P. Simonini and M. Leoni and P.A. VermeerE. Cascone and V. Bandini and A. Galletta and G. BiondiJ.-L. Chaumeny and J. Kirstein and S. VaraksinJ.-J. Chen and J.-D. NiuL.K. Korkiala-Tanttu and M.A. JuvankoskiR. Müller and S. LarssonE. φiseth and V. Thakur and A. WatnH. Schuller and P. KrameterT. Stapelfeldt and M. Lojander and H. Tanska and A. Ojala and J. ForsmanC. Wiltafsky and R. ThurnerP.H. Yonatan and J. Tennekoon and D. Van Gemert and J. Maertens and J. Houtmeyers and M. Goorden

Preface	p. IX
Organisers and sponsors	p. XI
Part I Keynote papers
Comparison of vibrocompaction methods by numerical simulations	p. 3
Settlement predictions of embankments on organic soils in engineering practice	p. 13
Installation effects of vibro replacement stone columns in soft clay	p. 23
Soil fracturing of soft silty clays for the reinforcement of a bell tower foundation	p. 31
Modelling of soft ground consolidation via combined surcharge and vacuum preloading	p. 43
Enhanced viscoplastic modelling of soft soils	p. 55
Modelling the influence of density and bonding on geomaterials	p. 65
Some experiences from full-scale test embankments on floating lime-cement columns	p. 77
3D numerical modelling of the behaviour of large buildings founded on Mexico City soft clays	p. 87
Frictional contact formulation for large deformation analyses in geomechanics	p. 95
Part II Constitutive and numerical modelling
Numerical analysis of embankments on soft soils incorporating vertical drains	p. 107
An experimentally-based constitutive model for deep-mix stabilized quick clay	p. 115
Numerical investigation on the factors affecting pullout resistance of driven nails in pyroclastic silty sand	p. 123
Modelling piled foundation by means of embedded piles	p. 131
Numerical analysis of a floating stone column foundation using different constitutive models	p. 137
Numerical modelling of small-scale geogrid encased sand column tests	p. 143
A unified method to describe the influences of intermediate principal stress and stress history in constitutive modelling	p. 151
Numerical modelling of deep mixed columns below embankments constructed on soft soils	p. 159
Validation of anisotropic creep model for soft soils	p. 165
Numerical modelling of a test embankment on soft clay improved with vertical drains	p. 173
Predicting horizontal deformations depending on the construction scheme using artificial intelligence	p. 181
Application of volume averaging technique in numerical modelling of deep mixing	p. 189
Three-dimensional analyses of PVD-improved soft soils	p. 197
Part III In situ and laboratory testing
Ground improvement with cement-rubberchip stabilisation	p. 207
Laboratory experimental analysis of radial consolidation around a stone column	p. 213
Model studies of circular foundations on soft soils	p. 219
Strength and permeability characteristics of cement stabilized soft finnish clay	p. 227
Soil improvement with vibrated stone columns-influence of pressure level and relative density on friction angle	p. 235
Evaluation of ground improvement by groups of vibro stone columns using field measurements and numerical analysis	p. 241
On the difficulty of characterizing the properties of mixed materials obtained from soil-cement columns	p. 249
Influence of curing temperature on the strength of cement-stabilised artificial clays	p. 257
Modelling destructuration and anisotropy of Bothkennar clay	p. 263
Collapse and deformation behaviour of alluvial loess soils from Afghanistan	p. 269
Characterization and modeling of consolidation and seepage behavior of soft sediment at low stress levels	p. 275
Centrifuge modelling to compare ground improvement techniques on double porosity clay landfills	p. 281
Finite element simulation of mandrel penetration in a normally consolidated soil	p. 287
A review of field trials investigating the performance of partial depth vibro stone columns in a deep soft clay deposit	p. 293
Evaluation of the effect of face bolting on tunnel construction using X-ray CT	p. 299
Numerical modelling of stone columns in soft clay under an embankment	p. 305
Shaft capacity of pre-stressed tubular concrete pile in marine soft ground	p. 313
Part IV Design methods
Investigating Priebe's method for settlement estimation of foundation resting on soil reinforced by stone columns	p. 321
A software programme for designing columnar reinforced soils	p. 327
Influence of stone column deformation on surrounding soil consolidation	p. 333
Design and construction of a sludge lock trench to prevent extrusion beneath an embankment	p. 339
Countermeasures against settlement of embankment on soft ground with PFS (Partial Floating Sheet-Pile) method	p. 345
On the numerical analysis of piled embankments	p. 353
Desig based on in-situ and laboratory tests in soft glacial soil	p. 361
Part V Case studies
Numerical creep analsis of the Treporti test embankment	p. 371
Acceleration of the consolidation process of a clayey soil by preloading and vertical drains: Field measurements and numerical predictions	p. 379
Consolidation of extremely soft mud for the AIRBUS A-380 assembly factory in Hamburg	p. 387
Behaviour of pile-net composite foundation	p. 393
Automated ground improvement process	p. 399
Veda trial embankment-comparison between measured and calculated deformations and pore pressure development	p. 405
Application of geosynthetics reinforcement in freezing thawing roads: A case study from Norway	p. 411
Construction of a lightweight dam on organic soils-FE-analyses and practical experiences	p. 417
Deep stabilised test embankment at the Suurpelto area in Espoo, Southern Finland	p. 423
Soil improvement by vibro replacement and preloading for the foundation of a shopping centre on weak marine deposits	p. 429
Construction of an embankment on an with an improved soft industrial sludge	p. 435
Author index	p. 443

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