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DEM simulations of transverse pipe–soil interaction on sand Géotechnique (IF 3.83) Pub Date : 2020-12-14 Giulia Macaro; Stefano Utili; Christopher M. Martin
Realistic modelling of transverse (i.e. vertical and lateral) pipe–soil interaction plays an important role in predicting the behaviour of untrenched offshore pipelines that are designed to undergo controlled lateral buckling. The large plastic soil deformations and surface geometry changes that occur during this process mean that numerical analyses using the continuum-based finite-element method are
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Effect of mean grain size on shear modulus degradation and damping ratio curves of sands Géotechnique (IF 3.83) Pub Date : 2020-12-14 Krepa Upreti; Eng-Choon Leong
Determination of shear modulus and damping ratio from small to large strains is essential to understand the non-linear stress–strain and damping behaviour of sand. The shear modulus and damping ratio with shear strain relationships of sand are dependent on a number of parameters: mean effective stress, void ratio, coefficient of uniformity, mean grain size and particle shape. The most common parameters
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Cyclic normal load–displacement behaviour of clay-coated sand grain contacts Géotechnique (IF 3.83) Pub Date : 2021-01-06 Sarvadevabhatla Sathwik Kasyap; Kostas Senetakis; Jidong Zhao
A micromechanical experimental study is presented in this paper investigating the normal contact response of quartz sand grains under cyclic loading. Sand grains with clean surfaces, termed uncoated, and grains coated with commercially available kaolinite powder were studied. The grain contacts were subjected to ten cycles of normal loading within a range from 0 to 5 N. It was observed that uncoated
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Probabilistic observational method for design of surcharges on vertical drains Géotechnique (IF 3.83) Pub Date : 2021-01-08 Johan Spross; Stefan Larsson
Preloading with a surcharge is today commonly used together with prefabricated vertical drains for embankment construction on clayey soil to accelerate primary consolidation and increase strength. Because of considerable uncertainty related mainly to the rate of consolidation, there is a need to account for this in the vertical drain and surcharge design to ensure quality in the embankment construction
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Non-linear soil–pile interaction induced by ground settlements: pile displacements and internal forces Géotechnique (IF 3.83) Pub Date : 2020-12-14 Andrea Franza; Alec M. Marshall; Rafael Jimenez
In urban areas, the construction of tunnels and deep excavations beneath and near pile foundations can be detrimental for the superstructure and the foundation. A two-stage continuum-based non-linear soil–pile interaction model is presented in this paper for predicting the axial and flexural response of piles affected by ground movements. The model accounts for the effects of near-pile non-linear (hyperbolic)
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Optimising the hydrophobicity of sands by silanisation and powder coating Géotechnique (IF 3.83) Pub Date : 2020-12-14 Yunesh Saulick; Sérgio D. N. Lourenço; Béatrice A. Baudet
Sands are naturally hydrophilic granular materials, yet, rendering them hydrophobic could lend them to a wide range of geotechnical applications. This study describes a powder-coating procedure performed after chemically modifying the surfaces of coarse, medium and fine sands and examines its effect on their hydrophobicity. The purpose is to render these granular materials more hydrophobic than what
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Thermal stress analysis of energy piles Géotechnique (IF 3.83) Pub Date : 2021-01-06 Cristiano Garbellini; Lyesse Laloui
This study is concerned with the problem of energy piles subjected to constant axial load and temperature variation uniform over the cross-section. In the first part of this paper, equations for the analysis of energy piles based on elastic theory and the load-transfer approach are described. Closed-form solutions are derived for a few simple cases. It is observed that temperature variation effects
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Simulation of overburden pressure during laboratory investigations of axial pipe–soil interaction Géotechnique (IF 3.83) Pub Date : 2020-12-14 Brian B. Sheil; Christopher M. Martin; Byron W. Byrne
The simulation of additional soil overburden pressure through the use of a surcharge system is a technique commonly adopted in laboratory testing of pipe–soil interaction. This paper examines the influence of surcharge boundary conditions and pressure level on the axial sliding behaviour of a trenched pipeline surrounded by sand backfill. A novel testing tank is employed in conjunction with a pressure
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Hydro-mechanical analysis of a surficial landslide triggered by artificial rainfall: the Ruedlingen field experiment Géotechnique (IF 3.83) Pub Date : 2020-12-14 Panagiotis Sitarenios; Francesca Casini; Amin Askarinejad; Sarah Springman
This paper interprets the hydromechanical behaviour of a steep, forested, instrumented slope during an artificial rainfall event, which triggered a shallow slope failure 15 h after rainfall initiation. The soil's mechanical response has been simulated by coupled hydro-mechanical finite-element analyses, using a critical state constitutive model that has been extended to unsaturated conditions. Failure
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Assessment of Skempton's pore water pressure parameters B and A using a high-capacity tensiometer Géotechnique (IF 3.83) Pub Date : 2020-12-14 Philip Sanlon; Vinayagamoothy Sivakumar; Brian Solan; Snehasis Tripathy; Pauline MacKinnon; Shane Donohue; Bathala Janaki Ramaiah
Saturation of soils is a prerequisite in many laboratory tests involving consolidation, permeability and stress–strain behaviour. The saturation process is usually time consuming, particularly in clay-rich soils, and this can incur substantial cost and potential delays in reporting findings. The saturation of samples is assessed using the well-established Skempton's pore water pressure parameter B
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A field investigation into the mechanisms of pile ageing in sand Géotechnique (IF 3.83) Pub Date : 2020-12-14 Kenneth Gavin; David Igoe
The design of axially loaded piles has been an area of focus for the offshore industry in recent years. A number of studies report substantial increases in the shaft capacity of piles driven in sand, known as pile ageing. The offshore industry has been slow to implement ageing into practice because of uncertainty over the mechanisms controlling ageing and variability on the impact of ageing. This paper
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A microstructural perspective on soil collapse Géotechnique (IF 3.83) Pub Date : 2020-12-16 Shengyang Yuan; Xianfeng Liu; Olivier Buzzi
Soil collapse is a phenomenon triggered by wetting a loaded soil, the structure of which contains large pores. This type of soil response has been studied since the 1970s and models that can predict its occurrence and magnitude were proposed from the 1990s. In particular, the concept of loading collapse (LC) curves has been developed in the framework of unsaturated soil mechanics and it has been validated
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Experimental and analytical study on electro-osmosis in low-permeability soil considering the pore size effect Géotechnique (IF 3.83) Pub Date : 2020-12-14 Haijun Zhou; Yingguang Fang; Minghua Chen; Renguo Gu; Wei Li
Existing electro-osmotic calculation models are mostly based on the assumption of a porous medium with uniform pores, whereas natural soil has pores of different sizes. This is especially significant in the case of low-permeability soil, whose pore size can vary over five or six orders of magnitude, from the nanometre to the millimetre scale. Experimental results have revealed significant differences
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Progressive failure in elastic–viscoplastic media: from theory to practice Géotechnique (IF 3.83) Pub Date : 2021-01-11 Claudio di Prisco; Luca Flessati
In the risk assessment of soil movement, the comprehension of unexpected collapses involving creeping landslides is crucial. The transition from creeping to fast landslides is very hard to justify theoretically and simulate numerically. In this paper, the authors intend to demonstrate that even the integration of a basic elastic strain softening constitutive relationship under simple shear conditions
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Measurements of permeability of saturated and unsaturated soils Géotechnique (IF 3.83) Pub Date : 2020-12-14 Pratiksha Pandey; Kaine Lynch; Vinayagamoorthy Sivakumar; Brian Solan; Snehasis Tripathy; Satyajeet Nanda; Shane Donohue
The management and engineering assessments of geotechnical assets within the national transportation inventory require an appropriate knowledge of permeability of saturated and unsaturated soils. Determination of the permeability of saturated soils can be carried out using direct measurements, whereas that of unsaturated soils is often made using indirect methods based on the soil water retention curve
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A design method for flexible retaining walls in clay Géotechnique (IF 3.83) Pub Date : 2020-12-14 Chuhan Deng; Stuart K. Haigh; Xianfeng Ma; Jiawei Xu
Design of retaining walls in clay is typically based on ultimate limit state calculations to prevent collapse, with arbitrary factors of safety used to limit deformations. These factors of safety do not take into account the different rates of strength mobilisation in the wide variety of clays found worldwide. As there is substantial uncertainty in this approach, conventional design tends to lead to
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Triggering and motion of landslides Géotechnique (IF 3.83) Pub Date : 2020-12-04 Eduardo E. Alonso
The paper analyses the dynamic behaviour of a class of landslides characterised by a well-defined failure surface where shear strains accumulate. The subject goes beyond the common concepts of safety factor and static analysis, and discusses procedures to identify the velocity and runout, once stability is lost. Three initial case histories serve to highlight the relevance of predicting the motion
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Physical modelling of lateral sand–pipe interaction Géotechnique (IF 3.83) Pub Date : 2020-12-04 Yousef Ansari; George Kouretzis; Scott William Sloan
This paper presents a series of physical modelling tests performed to measure the resistance developing during lateral dragging of a rigid pipe buried in loose to very dense dry sand. The experiments were performed in a small-scale prototype developed to model sand–pipe interaction during relative ground movement episodes while accurately controlling the density and uniformity of sand around the pipe
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Experimental determination of the shear strength of peat from standard undrained triaxial tests: correcting for the effects of end restraint Géotechnique (IF 3.83) Pub Date : 2020-12-04 Stefano Muraro; Cristina Jommi
Conventional triaxial tests on peats are strongly criticised due to the very high shear strength parameters obtained from standard data elaboration, leading to unrealistic factors of safety when used in geotechnical design and assessment. Various operational approaches have been proposed in the literature to overcome this difficulty; however, they seem to lack consistent mechanical background. Some
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Mechanisms beneath rectangular shallow foundations on sands: vertical loading Géotechnique (IF 3.83) Pub Date : 2020-11-17 Yining Teng; Sam A. Stanier; Susan M. Gourvenec
This paper details analysis of deformation behaviour of silica and carbonate sands under a rectangular foundation subject to uniaxial vertical load based on results from a series of centrifuge model tests. A multiscale particle image velocimetry/digital image correlation (PIV/DIC) technique was used to record and analyse the foundation tests with high resolution and measurement precision. Cone penetrometer
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A state-dependent constitutive model for methane hydrate-bearing sediments inside the stability region Géotechnique (IF 3.83) Pub Date : 2020-11-17 Charles Wang Wai Ng; Sina Baghbanrezvan; Tomas Kadlicek; Chao Zhou
The presence of methane hydrate in soil pores alters the stress–strain and volumetric behaviour of soil. The extent of this alteration is affected by initial temperature and pore pressure when hydrate is formed inside the thermodynamically stable region. In this paper, a state-dependent critical state model is developed for methane hydrate-bearing sediments (MHBS) within the theoretical framework of
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A modified Davis approach for geotechnical stability analysis involving non-associated soil plasticity Géotechnique (IF 3.83) Pub Date : 2020-11-17 Xi Chen; Dongyong Wang; Yuzhen Yu; Yannan Lyu
For geotechnical stability analysis involving non-associated plasticity, the Davis approach with internal friction angle and dilatancy angle updated during the strength reduction process can lead to an improvement over the Davis approach without updating the two angles, according to recent studies. However, the Davis approach with internal friction angle and dilatancy angle updated may be overly conservative
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Diameter assessment of soilcrete column using in-hole electrical resistivity tomography Géotechnique (IF 3.83) Pub Date : 2020-11-17 Chun-Hung Lin; Chih-Ping Lin; Yin Jeh Ngui; Haoran Wang; Po-Lin Wu; Guan-Jie He; Hsin-Chang Liu
Quality control of jet grouting at large depth is a challenging task. An in-hole electrical resistivity method was recently shown to have high potential for assessing the diameter and integrity of jet grouting. To facilitate visualised inspection and practical use of the in-hole resistivity method for jet grouting, this study introduces a novel and practical tomographic approach. An analogous mapping
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Adhesion-force micro-scale study of desiccating granular material Géotechnique (IF 3.83) Pub Date : 2020-11-17 Tomasz Hueckel; Boleslaw Mielniczuk; Moulay Said El Youssoufi
Experiments on five-, four-, three- and two-wet-hydrophilic-grain clusters were performed to investigate evolution of adhesion of granular media during drying on the micro-scale. The experiments show that the adhesion-force of a cluster initially grows at most to three times the original value before decreasing to zero by the end of evaporation. The adhesion-force is composed of capillary pressure
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Statistical charts for determining sample size at various levels of accuracy and confidence in geotechnical site investigation Géotechnique (IF 3.83) Pub Date : 2020-11-17 Zheng Guan; Yu Wang
Site investigation is indispensable in geotechnical practice, but only a small portion of the soil affected by the intended geotechnical construction is examined and/or tested in the laboratory or in situ, leading to significant uncertainties in site investigation results. The uncertainty in the site investigation results depends greatly on the number of specimens tested (i.e. sample size) during site
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Penetrometer testing in a calcareous silt to explore changes in soil strength Géotechnique (IF 3.83) Pub Date : 2020-11-17 Shiao Huey Chow; Conleth D. O'Loughlin; Zefeng Zhou; David J. White; Mark F. Randolph
This paper describes a centrifuge study using a range of penetrometer tests (T-bar, piezocone and free-fall piezocone) to explore strength changes in a reconstituted, normally consolidated, natural calcareous silt. Various penetrometer test procedures were applied to measure the penetration resistances including monotonic, cyclic and twitch-type movements as well as pauses for pore pressure dissipation
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Ground characterisation for PISA pile testing and analysis Géotechnique (IF 3.83) Pub Date : 2020-10-21 Lidija Zdravković; Richard J. Jardine; David M. G. Taborda; David Abadias; Harvey J. Burd; Byron W. Byrne; Kenneth G. Gavin; Guy T. Houlsby; David J. P. Igoe; Tingfa Liu; Christopher M. Martin; Ross A. McAdam; Alastair Muir Wood; David M. Potts; Jesper Skov Gretlund; Emil Ushev
This paper is the first of a set of linked publications on the PISA Joint Industry Research Project, which was concerned with the development of improved design methods for monopile foundations in offshore wind applications. PISA involved large-scale pile tests in overconsolidated glacial till at Cowden, north-east England, and in dense, normally consolidated marine sand at Dunkirk, northern France
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New data analysis methods for instrumented medium-scale monopile field tests Géotechnique (IF 3.83) Pub Date : 2020-10-21 Harvey J. Burd; William J. A. P. Beuckelaers; Byron W. Byrne; Kenneth G. Gavin; Guy T. Houlsby; David J. P. Igoe; Richard J. Jardine; Christopher M. Martin; Ross A. McAdam; Alastair Muir Wood; David M. Potts; Jesper Skov Gretlund; David M. G. Taborda; Lidija Zdravković
The PISA Joint Industry Research Project was concerned with the development of improved design methods for monopile foundations in offshore wind applications. PISA involved large-scale pile tests in overconsolidated glacial till at Cowden, north-east England, and in dense, normally consolidated marine sand at Dunkirk, northern France. This paper describes the experimental set-up for pile testing, with
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Monotonic laterally loaded pile testing in a stiff glacial clay till at Cowden Géotechnique (IF 3.83) Pub Date : 2020-10-21 Byron W. Byrne; Ross A. McAdam; Harvey J. Burd; William J. A. P. Beuckelaers; Kenneth G. Gavin; Guy T. Houlsby; David J. P. Igoe; Richard J. Jardine; Christopher M. Martin; Alastair Muir Wood; David M. Potts; Jesper Skov Gretlund; David M. G. Taborda; Lidija Zdravković
This paper describes the results obtained from a field testing campaign on laterally loaded monopiles conducted at Cowden, UK, where the soil consists principally of a heavily overconsolidated glacial till. These tests formed part of the PISA project on the development of improved design methods for monopile foundations for offshore wind turbines. Results obtained for monotonic loading tests on piles
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Monotonic laterally loaded pile testing in a dense marine sand at Dunkirk Géotechnique (IF 3.83) Pub Date : 2020-10-21 Ross A. McAdam; Byron W. Byrne; Guy T. Houlsby; William J. A. P. Beuckelaers; Harvey J. Burd; Kenneth G. Gavin; David J. P. Igoe; Richard J. Jardine; Christopher M. Martin; Alastair Muir Wood; David M. Potts; Jesper Skov Gretlund; David M. G. Taborda; Lidija Zdravković
The results obtained from a field testing campaign on laterally loaded monopiles, conducted at a dense sand site in Dunkirk, northern France are described. These tests formed part of the PISA project on the development of improved design methods for monopile foundations for offshore wind turbines. Results obtained from monotonic loading tests on piles of three different diameters (0·273 m, 0·762 m
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Finite-element modelling of laterally loaded piles in a stiff glacial clay till at Cowden Géotechnique (IF 3.83) Pub Date : 2020-10-21 Lidija Zdravković; David M. G. Taborda; David M. Potts; David Abadias; Harvey J. Burd; Byron W. Byrne; Kenneth G. Gavin; Guy T. Houlsby; Richard J. Jardine; Christopher M. Martin; Ross A. McAdam; Emil Ushev
The PISA project was a combined field testing/numerical modelling study with the aim of developing improved design procedures for large-diameter piles subjected to lateral loading. This paper describes the development of a three-dimensional finite-element model for the medium-scale pile tests that were conducted in Cowden till as part of the PISA work. The paper places particular emphasis on the consistent
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Finite-element modelling of laterally loaded piles in a dense marine sand at Dunkirk Géotechnique (IF 3.83) Pub Date : 2020-10-21 David M. G. Taborda; Lidija Zdravković; David M. Potts; Harvey J. Burd; Byron W. Byrne; Kenneth G. Gavin; Guy T. Houlsby; Richard J. Jardine; Tingfa Liu; Christopher M. Martin; Ross A. McAdam
The paper presents the development of a three-dimensional finite-element model for pile tests in dense Dunkirk sand, conducted as part of the PISA project. The project was aimed at developing improved design methods for laterally loaded piles, as used in offshore wind turbine foundations. The importance of the consistent and integrated interpretation of the soil data from laboratory and field investigations
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PISA design model for monopiles for offshore wind turbines: application to a stiff glacial clay till Géotechnique (IF 3.83) Pub Date : 2020-10-21 Byron W. Byrne; Guy T. Houlsby; Harvey J. Burd; Kenneth G. Gavin; David J. P. Igoe; Richard J. Jardine; Christopher M. Martin; Ross A. McAdam; David M. Potts; David M. G. Taborda; Lidija Zdravković
Offshore wind turbines in shallow coastal waters are typically supported on monopile foundations. Although three-dimensional (3D) finite-element methods are available for the design of monopiles in this context, much of the routine design work is currently conducted using simplified one-dimensional (1D) models based on the p–y method. The p–y method was originally developed for the relatively large
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PISA design model for monopiles for offshore wind turbines: application to a marine sand Géotechnique (IF 3.83) Pub Date : 2020-10-21 Harvey J. Burd; David M. G. Taborda; Lidija Zdravković; Christelle N. Abadie; Byron W. Byrne; Guy T. Houlsby; Kenneth G. Gavin; David J. P. Igoe; Richard J. Jardine; Christopher M. Martin; Ross A. McAdam; Antonio M. G. Pedro; David M. Potts
This paper describes a one-dimensional (1D) computational model for the analysis and design of laterally loaded monopile foundations for offshore wind turbine applications. The model represents the monopile as an embedded beam and specially formulated functions, referred to as soil reaction curves, are employed to represent the various components of soil reaction that are assumed to act on the pile
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Application of the PISA design model to monopiles embedded in layered soils Géotechnique (IF 3.83) Pub Date : 2020-10-21 Harvey J. Burd; Christelle N. Abadie; Byron W. Byrne; Guy T. Houlsby; Christopher M. Martin; Ross A. McAdam; Richard J. Jardine; Antonio M. G. Pedro; David M. Potts; David M. G. Taborda; Lidija Zdravković; Miguel Pacheco Andrade
The PISA design model is a procedure for the analysis of monopile foundations for offshore wind turbine applications. This design model has been previously calibrated for homogeneous soils; this paper extends the modelling approach to the analysis of monopiles installed at sites where the soil profile is layered. The paper describes a computational study on monopiles embedded in layered soil configurations
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Unified thixotropic fluid model for soil liquefaction Géotechnique (IF 3.83) Pub Date : 2020-09-14 Zhihua Wang; Jinlong Ma; Hongmei Gao; Armin W. Stuedlein; Jian He; Binghui Wang
The geotechnical earthquake engineering profession has struggled with the inherent complexity of the multiphase soil response to cyclic loading owing to the progressive nature of the generation of excess pore pressure (EPP) and degradation of soil stiffness and strength. One approach to improve understanding of the cyclic response and correlate the transition from a two-phase saturated soil to a single
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Soil water content–water activity relations of structured kaolinitic specimens from GAB equation Géotechnique (IF 3.83) Pub Date : 2020-09-14 Sudhakar M. Rao; Monica Rekapalli
The GAB (Guggenheim–Anderson–de Boer) equation is explored to describe the relation between equilibrium soil water content (wequil) and water activity (relative humidity) of structured kaolinitic soils along the drying path. The equation is chosen as it has the advantage of a theoretical basis and can describe sorption behaviour of soils over a wide range of water activities. The GAB parameters evaluated
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Effects of plant growth and spacing on soil hydrological changes: a field study Géotechnique (IF 3.83) Pub Date : 2020-09-14 Charles Wang Wai Ng; Jun Jun Ni; Anthony Kwan Leung
Effects of plant growth on soil hydrological changes need to be considered for long-term vegetation management of geotechnical infrastructure. Most existing studies focused on one particular plant age. This study quantifies the effects of plant growth on the evolution of soil hydraulic properties and matric suction over time, through field monitoring and numerical soil–plant–atmosphere interaction
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Alternative method to determine the uniaxial-strain compressibility of cohesive sandstone Géotechnique (IF 3.83) Pub Date : 2020-09-14 Sander Hol; Arjan van der Linden
Compaction and subsidence risk related to hydrocarbon production are frequently assessed using Geertsma models. The underlying theory assumes linear poroelastic reservoir rock to compress by pore pressure depletion under uniaxial-strain conditions. Adequate mechanical testing techniques have been developed to measure the uniaxial-strain compressibility, although the execution of these methods is technically
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Granular flow simulation in a centrifugal acceleration field Géotechnique (IF 3.83) Pub Date : 2020-09-14 Miguel Angel Cabrera; Alessandro Leonardi; Chong Peng
The use of the geotechnical centrifuge to obtain scaled physical models is a useful tool in geomechanics. When dealing with granular flows, however, the traditional scaling principles are challenged by the complex rheology of the material and by the non-trivial effects of the Coriolis apparent acceleration. In a laboratory centrifuge, obtaining a clear understanding of these effects is further complicated
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Micromechanical investigation of liquefaction of granular media by cyclic 3D DEM tests Géotechnique (IF 3.83) Pub Date : 2020-09-14 Eduardo L. Martin; Colin Thornton; Stefano Utili
In order to evaluate numerically the seismic-induced liquefaction potential of gravelly soils, three-dimensional discrete-element method cyclic undrained triaxial tests were performed in a periodic cell. The undrained tests were conducted by deforming the samples under constant volume conditions. The paper presents a detailed investigation into the mechanical phenomena occurring at the grain scale
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Monopile rotation under complex cyclic lateral loading in sand Géotechnique (IF 3.83) Pub Date : 2020-09-14 Iona A. Richards; Byron W. Byrne; Guy T. Houlsby
Monopiles supporting offshore wind turbines experience combined moment and horizontal loading which is both cyclic and complex – continuously varying in amplitude, direction and frequency. The accumulation of rotation with cyclic loading (ratcheting) is a key concern for monopile designers and has been explored in previous experimental studies, where constant-amplitude cyclic tests have shown rotation
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A micro finite-element model for soil behaviour: experimental evaluation for sand under triaxial compression Géotechnique (IF 3.83) Pub Date : 2020-09-14 Sadegh Nadimi; Joana Fonseca; Edward Andò; Gioacchino Viggiani
This note evaluates the ability of a combined discrete–finite-element approach to replicate the experimental response of a dry sand under triaxial compression. The numerical sample was created by virtualising the fabric of a Martian regolith-like sand sample obtained from an in situ test using X-ray micro computed tomography; physical properties of the grains obtained from laboratory data were used
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Mathematical modelling of the mechanical response of earth embankments on piled foundations Géotechnique (IF 3.83) Pub Date : 2020-08-17 Claudio di Prisco; Luca Flessati; Gabriele Frigerio; Andrea Galli
Piled foundations are largely employed as settlement reducers in the design of artificial embankments on soft soil strata. The commonly employed design methods are, however, based on simplified approaches not allowing the assessment of average and differential settlements at the top of the embankment. With this objective, the authors introduce a generalised constitutive relationship capable of accounting
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Behaviour of discrete piles used to stabilise a tree-covered railway embankment Géotechnique (IF 3.83) Pub Date : 2020-08-17 Joel A. Smethurst; Nicola Bicocchi; William Powrie; Anthony S. O'Brien
Many clay railway embankments in the UK are well over 100 years old, and now suffer from a range of stability and serviceability problems. A common means of remediating earthworks that have either suffered, or are assessed as being at risk of, deep-seated slope failure is to install a row of discrete piles along the mid-slope. This paper presents field data from a 9 m high, pile-stabilised embankment
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Relating shaft friction of buried piles and CPT resistance in clayey sands Géotechnique (IF 3.83) Pub Date : 2020-08-17 L. V. Doan; B. M. Lehane
This paper examines factors controlling the ultimate shaft friction developed on buried piles in normally consolidated clay–sand mixtures and explores the relationship between this friction and the cone penetration test (CPT) end resistance. Results from tension load tests on buried piles in a laboratory pressure chamber and geotechnical centrifuge are presented. Variable rate CPTs combined with Rowe
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Analysing the effect of principal stress rotation on railway track settlement by discrete element method Géotechnique (IF 3.83) Pub Date : 2020-08-17 Xuecheng Bian; Wei Li; Yu Qian; Erol Tutumluer
Principal stress rotation induced by moving loads from trains significantly influences railway track settlement accumulation. The stationary cyclic loading commonly adopted to study railway ballast behaviour under repeated train loading cannot fully represent the effects of principal stress rotation, which needs to be properly considered in both laboratory tests and numerical simulations for a better
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Normalised behaviour of a non-plastic silt–pumice sand mixture Géotechnique (IF 3.83) Pub Date : 2020-08-17 Lu Zuo; Beatrice A. Baudet
The existence and failures of silty sand have been reported worldwide, and the behaviour of sand–silt mixtures at small to large strains has been intensively studied. Owing to the relatively low stress level achieved in laboratory testing, no unifying framework has yet been proposed for sand–silt mixtures. In the presented work, a crushable sand, made of pumice, was used as host sand so as to reach
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Full-scale observations of dynamic and static axial responses of offshore piles driven in chalk and tills Géotechnique (IF 3.83) Pub Date : 2020-07-14 Roisin M. Buckley; Richard J. Jardine; Stavroula Kontoe; Pedro Barbosa; Felix C. Schroeder
This paper describes and interprets tests on piles driven through glacial tills and chalk at a Baltic Sea windfarm, covering an advance trial campaign and later production piling. The trials involved six instrumented 1·37 m dia. steel open-ended tubes driven in water depths up to 42 m. Three piles were tested statically, with dynamic re-strike tests on paired piles, at 12–15 week ages. Instrumented
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Evaluation of soil models for improved design of offshore wind turbine foundations in dense sand Géotechnique (IF 3.83) Pub Date : 2020-07-14 Hans Petter Jostad; Birgitte Misund Dahl; Ana Page; Nallathamby Sivasithamparam; Hendrik Sturm
In order to perform optimised and safe design of foundations for offshore wind turbines (OWT), it is important to have calculation tools that describe the key features of water-saturated soil subjected to complex and irregular loading over a wide range of strain levels. Soils subjected to cyclic loading are prone to strain accumulation. The accumulated (plastic) volumetric strain may result in excess
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Effect of torsion on the undrained limiting lateral resistance of piles in clay Géotechnique (IF 3.83) Pub Date : 2020-07-14 Konstantinos Georgiadis; Brian Sheil
The behaviour of piles subjected to lateral loads has been explored by a number of investigators over the past five decades. However, the vast majority of the previous literature has ignored the potential influence of additional torsional effects due to horizontal eccentricities of the applied lateral loads. In this paper, an upper bound mechanism and a lower bound stress field are presented for the
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A macro-element approach to analyse bridge abutments accounting for the dynamic behaviour of the superstructure Géotechnique (IF 3.83) Pub Date : 2020-07-14 Davide Noè Gorini; Luigi Callisto
This paper describes an original approach to the study of the seismic behaviour of bridge abutments. The proposed method incorporates a simplified description of the dynamic response of the bridge structure into a finite-element model of the soil–abutment system. Specifically, the dynamic behaviour of the bridge structure is described by a macro-element that simulates the loads transferred to the abutment
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Consolidation effects on monotonic and cyclic capacity of plate anchors in sand Géotechnique (IF 3.83) Pub Date : 2020-07-14 Shiao Huey Chow; Andrea Diambra; Conleth D. O'Loughlin; Christophe Gaudin; Mark F. Randolph
This study investigated the change in monotonic and cyclic capacity of a plate anchor across different degrees of consolidation in dense sand. To quantify the effect of consolidation on anchor capacity, a framework is introduced and validated using centrifuge model anchor test data. The centrifuge tests considered a rectangular plate loaded at varying rates in dense sand, under both monotonic and irregular
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Improvements in plate anchor capacity due to cyclic and maintained loads combined with consolidation Géotechnique (IF 3.83) Pub Date : 2020-07-14 Zefeng Zhou; Conleth D. O'Loughlin; David J. White; Sam A. Stanier
Plate anchor technology is an efficient solution for mooring offshore floating facilities for oil and gas or renewable energy projects. When used with a taut mooring, the anchor is typically subjected to a maintained load component and intermittent episodes of cyclic loading throughout the design life. These loads, and the associated shearing, remoulding and consolidation processes, cause changes in
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Modelling the long-term hydro-mechanical behaviour of a bentonite pellet/powder mixture with consideration of initial structural heterogeneities Géotechnique (IF 3.83) Pub Date : 2020-06-16 Nadia Mokni; Agustín Molinero Guerra; Yu-Jun Cui; Pierre Delage; Patrick Aimedieu; Michel Bornert; Anh Minh Tang
The aim of this paper is to investigate the long-term hydro-mechanical behaviour of a highly heterogeneous MX80 bentonite pellet/powder mixture (80/20 in dry mass), which is one of the candidate sealing materials in deep geological repositories. In spite of the operational advantages related to the use of the mixture, structural heterogeneities resulting from the installation process constitute a matter
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Soil, basin and soil–building–soil interaction effects on motions of Mexico City during seven earthquakes Géotechnique (IF 3.83) Pub Date : 2020-06-16 Evangelia Garini; Ioannis Anastasopoulos; George Gazetas
Starting with the destructive 1985 Michoacan Mw 8·0 earthquake, the lake zone of Mexico City has been experiencing ground motions bearing the effects of strong soil amplification at specific site-dependent periods. Last year's Mw = 7·1 Puebla earthquake, although less damaging, with different orientation and mechanism, and at a much shorter distance than the 1985 event, nevertheless produced records
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Saturated granular flows: constitutive modelling under steady simple shear conditions Géotechnique (IF 3.83) Pub Date : 2020-06-16 Dalila Vescovi; Pietro Marveggio; Claudio Giulio Di Prisco
In this paper, the authors analyse numerical and experimental results concerning either dry or saturated granular flows under steady, simple shear conditions. A new constitutive model is introduced, on the base of the mixture theory, according to which granular and liquid phases are considered separately. The constitutive relationship refers to the representative elementary volume and assumes that
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Local deformation behaviour of saturated silica sand during undrained cyclic torsional shear tests using image analysis Géotechnique (IF 3.83) Pub Date : 2020-06-16 Chuang Zhao; Junichi Koseki; Weichen Liu
A series of undrained cyclic torsional shear tests was conducted to investigate the development of local deformations of silica sand specimens directly using an image-based technique and a transparent membrane. The results for saturated sand specimens with varying densities showed that the vertical slippage of sand particles relative to the membrane was initiated at the liquefaction stage. Additionally
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A simplified approach to normalisation of piezocone penetration rate effects Géotechnique (IF 3.83) Pub Date : 2020-06-16 Fernando Schnaid; Gracieli Dienstmann; Edgar Odebrecht; Samir Maghous
The influence of factors controlling the rate of penetration during piezocone tests (CPTU) is addressed in the present paper, including a critical appraisal of measurements adopted as input in existing dimensionless analysis. From a heuristic approach, a method is proposed to identify possible consolidation effects taking place during penetration using the velocity factor, V¯h . Defined as a direct
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Field experiments at three sites to investigate the effects of age on steel piles driven in sand Géotechnique (IF 3.83) Pub Date : 2020-05-18 R. Carroll; P. Carotenuto; C. Dano; I. Salama; M. Silva; S. Rimoy; K. Gavin; R. Jardine
This paper investigates the influences that steel type, in situ soil properties, water table depth, pile diameter, roughness and driving procedures have on the ageing behaviour of piles driven in sand. Tension tests have been performed on 51 open-ended steel micro-piles, with 48 to 60 mm outside diameter, driven at well-established research sites at Larvik in Norway, Dunkirk in France and Blessington
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