Geotechnics of Soft Soils: Focus on Ground Improvement: Proceedings of the 2nd International Workshop held in Glasgow, Scotland, 3 - 5 September 2008

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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 ‘Soft Clay Modelling for Engineering Practice (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.

Author(s): Minna Karstunen, Martino Leoni
Edition: 1 Har/Cdr
Publisher: Taylor & Francis
Year: 2008

Language: English
Commentary: 69430
Pages: 458

Front cover......Page 1
Table of contents......Page 6
Preface......Page 10
Organisers and sponsors......Page 12
Part I Keynote papers......Page 14
Comparison of vibrocompaction methods by numerical simulations......Page 16
Settlement predictions of embankments on organic soils in engineering practice......Page 26
Installation effects of vibro replacement stone columns in soft clay......Page 36
Soil fracturing of soft silty clays for the reinforcement of a bell tower foundation......Page 44
Modelling of soft ground consolidation via combined surcharge and vacuum preloading......Page 56
(c)......Page 59
Enhanced viscoplastic modelling of soft soils......Page 68
Modelling the influence of density and bonding on geomaterials......Page 78
Some experiences from full-scale test embankments on floating lime-cement columns......Page 90
3D numerical modelling of the behaviour of large buildings founded on Mexico City soft clays......Page 100
Frictional contact formulation for large deformation analyses in geomechanics......Page 108
Part II Constitutive and numerical modelling......Page 118
Numerical analysis of embankments on soft soils incorporating vertical drains......Page 120
An experimentally-based constitutive model for deep-mix stabilized quick clay......Page 128
Numerical investigation on the factors affecting pullout resistance of driven nails in pyroclastic silty sand......Page 136
Modelling piled foundation by means of embedded piles......Page 144
Numerical analysis of a floating stone column foundation using different constitutive models......Page 150
Numerical modelling of small-scale geogrid encased sand column tests......Page 156
A unified method to describe the influences of intermediate principal stress and stress history in constitutive modelling......Page 164
Numerical modelling of deep mixed columns below embankments constructed on soft soils......Page 172
Validation of anisotropic creep model for soft soils......Page 178
Numerical modelling of a test embankment on soft clay improved with vertical drains......Page 186
Predicting horizontal deformations depending on the construction scheme using artificial intelligence......Page 194
Application of volume averaging technique in numerical modelling of deep mixing......Page 202
Three-dimensional analyses of PVD-improved soft soils......Page 210
Part III In situ and laboratory testing......Page 218
Ground improvement with cement-rubberchip stabilisation......Page 220
Laboratory experimental analysis of radial consolidation around a stone column......Page 226
Model studies of circular foundations on soft soils......Page 232
Strength and permeability characteristics of cement stabilized soft finnish clay......Page 240
Soil improvement with vibrated stone columns—influence of pressure level and relative density on friction angle......Page 248
Evaluation of ground improvement by groups of vibro stone columns using field measurements and numerical analysis......Page 254
On the difficulty of characterizing the properties of mixed materials obtained from soil-cement columns......Page 262
Influence of curing temperature on the strength of cement-stabilised artificial clays......Page 270
Modelling destructuration and anisotropy of Bothkennar clay......Page 276
Collapse and deformation behaviour of alluvial loess soils from Afghanistan......Page 282
Characterization and modeling of consolidation and seepage behavior of soft sediment at low stress levels......Page 288
Centrifuge modelling to compare ground improvement techniques on double porosity clay landfills......Page 294
Finite element simulation of mandrel penetration in a normally consolidated soil......Page 300
A review of field trials investigating the performance of partial depth vibro stone columns in a deep soft clay deposit......Page 306
Evaluation of the effect of face bolting on tunnel construction using X-ray CT......Page 312
Numerical modelling of stone columns in soft clay under an embankment......Page 318
Shaft capacity of pre-stressed tubular concrete pile in marine soft ground......Page 326
Part IV Design methods......Page 332
Investigating Priebe’s method for settlement estimation of foundation resting on soil reinforced by stone columns......Page 334
A software programme for designing columnar reinforced soils......Page 340
Influence of stone column deformation on surrounding soil consolidation......Page 346
Design and construction of a sludge lock trench to prevent extrusion beneath an embankment......Page 352
Countermeasures against settlement of embankment on soft ground with PFS (Partial Floating Sheet-Pile) method......Page 358
On the numerical analysis of piled embankments......Page 366
Design based on in-situ and laboratory tests in soft glacial soil......Page 374
Part V Case studies......Page 382
Numerical creep analysis of the Treporti test embankment......Page 384
Acceleration of the consolidation process of a clayey soil by preloading and vertical drains: Field measurements and numerical predictions......Page 392
Consolidation of extremely soft mud for the AIRBUS A-380 assembly factory in Hamburg......Page 400
Behavior of pile-net composite foundation......Page 406
Automated ground improvement process......Page 412
Veda trial embankment—comparison between measured and calculated deformations and pore pressure development......Page 418
Application of geosynthetics reinforcement in freezing thawing roads: A case study from Norway......Page 424
Construction of a lightweight dam on organic soils—FE-analyses and practical experiences......Page 430
Deep stabilised test embankment at the Suurpelto area in Espoo, Southern Finland......Page 436
Soil improvement by vibro replacement and preloading for the foundation of a shopping centre on weak marine deposits......Page 442
Construction of an embankment on and with an improved soft industrial sludge......Page 448
Author index......Page 456
Back cover......Page 458