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

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

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

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

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)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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