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 bearing capacity of shallow foundations may decrease when located near slopes, particularly under seismic conditions. However, there is limited work that isolates the destabilising influences of seismicity and finite slope geometry on ultimate bearing capacity in terms of conventional bearing capacity factors. Herein, analytical solutions based on upper-bound kinematic limit analysis are used to

This note describes a faster and complete consolidation testing procedure using the inflection point method so as to obtain the void ratio–consolidation curve at the end-of-primary consolidation and the coefficient of consolidation. The testing procedure is similar to the conventional incremental load consolidation test, with the only difference being that the subsequent loading is applied once the

This paper describes an experimental study aimed at evaluating the influence of soil microstructure on air permeability in compacted clay. Air permeability measurements, estimated using the gas pressure decay method, were carried out for a wide range of compaction states. The evolution of the air permeability during wetting and drying paths was also evaluated. The experimental results show that, for

Polymer solutions are now commonly used as excavation-support fluids for the construction of bored piles (drilled shafts) and diaphragm walls around the world. Fluids based on synthetic polymers have several advantages over the conventional bentonite-based slurries, including improved foundation performance, smaller site footprint and reduced environmental impact. However, the flow behaviour of polymer

Fault deformation can cause severe damage to structures located within the fault zones. A logarithmic spiral model was developed by D. A. Cole and P. V. Lade in 1984 to predict the shapes and locations of fault ruptures in sand caused by dip–slip faulting, based on 1g sandbox tests. However, it shows poor predictions for reverse fault ruptures observed in centrifuge tests. In this study, centrifuge

A relationship between elastic anisotropy, as typically observed in clayey soils subjected to shear wave propagation tests, and plastic anisotropy, detected at yielding and leading to rotated yield loci, is proposed. Such a relationship is expected because both elastic and plastic anisotropies can be ascribed to the same directional ingredients that characterise the fabric of the soil at the microscale

Water infiltration into granular soils and the associated pore water pressure increase and reduction in shear strength can trigger landslides, instability of vertical cuts and failure of retaining walls. Water-repellent soils can reduce infiltration to maintain soil suction. Recent research has demonstrated the creation of synthetic water-repellent soils using chemical methods. This paper investigates

A critical state testing round robin programme was carried out on sandy silt gold tailings. This involved 15 laboratories around the world testing a sandy silt tailings to infer its critical state line (CSL). Methods to be used were intentionally not supplied to participants, to enable the current methods being employed in industry and academia to be obtained in an unbiased manner. All but one of the

In this paper, the influence of the foundation configuration (raft or separate footings) on tunnel–soil–framed building interaction is investigated using geotechnical centrifuge testing. Tunnelling-induced soil movements and deformation fields, framed building displacements and structure shear distortions (with associated modification factors) are illustrated. Framed building stiffness and footing

This paper presents the assessment of consolidation and creep settlements of an isolated circular footing supported on soft clay samples reinforced with a single granular column. Clay samples (300 mm dia., 400 mm high) were formed from reconstituted kaolin and remoulded sleech (exhibiting significant creep). These samples were tested using chambers with various features to capture the settlement under

Waste glass is a solid residue usually available near urban centres, where it is discarded after being used as a container for one of several products. Carbide lime (CL) is a by-product of the manufacture of acetylene gas. The present research evaluates the potential of combining these two wastes as a possible hydraulic cement to enhance the behaviour of sands. Pozzolanic reactions occur between silica

In this paper a water retention model is developed based on soil mineralogy and microscopic features of material behaviour. The model estimates the water content at a given total suction as the sum of the bentonite minerals’ interlayer water and water in the interparticle pores. The paper proposes simple formulae to estimate the interlayer water content and interlayer void ratio based on mineralogical

Lateral soil pressures under at-rest conditions are commonly estimated as K0 times vertical normal pressure, where K0 is obtained from generally accepted empirical formulae, related to the soil's friction angle and the stress history. Results of a programme of laterally, rigidly confined, vertical compression and unloading tests on sand and clay are presented, in which two significant experimental

Microbial (or bio-) desaturation is a new method for mitigation of the liquefaction hazard of sand. In this paper, a series of monotonic and cyclic triaxial tests was performed on bio-desaturated sand under undrained conditions to demonstrate that the bio-desaturation method is effective in enhancing the liquefaction resistance of sand under either monotonic or cyclic loading conditions. The test results

The Callovo-Oxfordian (COx) claystone is chosen as a potential geological barrier for the geological repository of radioactive waste in France, and high-performance concrete is used as a sealing plug and lining in repository facilities. In this study, the shear strength of the interface between the concrete and claystone is investigated in particular. Ultra-high-performance (UHP) concrete is directly

Fibre orientation in fibre-reinforced sand (FRS) is highly anisotropic due to compaction during sample preparation or field construction. This makes the mechanical behaviour of FRS, such as strength and dilatancy, highly dependent on the strain increment direction. While constitutive models that are able to capture such anisotropic behaviour of FRS have been proposed for conventional triaxial compression

The study of the seismic response of inhomogeneous soil deposits, underlying rigid bedrock, has traditionally been framed as a one-dimensional wave propagation problem in a linear viscoelastic medium. When it comes to modelling soil inhomogeneity, the current trend to model the continuous variation of soil stiffness with depth employs a ‘generalised parabolic function’. Exact solutions have already

Spatially variable cement-treated ground can be considered, in design, as a uniform medium with appropriately reduced strength. Various strength reduction factors have been proposed for cement-treated ground under different loading conditions. However, the Tresca and Mohr–Coulomb models, which are widely used to represent the behaviour of the improved soil in geotechnical design, do not replicate the

The discrete-element method (DEM) was used to simulate constant-volume (undrained) triaxial compression tests for coarse particles (sand) mixed with non-plastic fines. Simulations were performed on granular mixtures with a range of fines contents (fc) – namely, 0, 0·05, 0·10 and 0·20. The critical state and micromechanical responses of these mixtures were evaluated. The influence of fc on sand behaviour

The response of shallow geotechnical structures is affected by interaction with the atmosphere. Since the ground surface is very often vegetated, plant transpiration plays a major role in such an interaction. Transpiration in geotechnical applications is generally modelled by way of a transpiration reduction function (e.g. the Feddes function). However, its parameters are generally borrowed from the

This paper presents results from a systematic investigation of footing response in four different types of sands placed and tested under controlled conditions in a geotechnical centrifuge. A parallel series of cone penetration tests (CPTs) was performed to examine correlations between CPT end resistance (qc) and footing bearing pressure (q). The experimental results show that there is a unique relationship

In this paper, the lateral limiting pressure on square pile groups in undrained soil is explored using two-dimensional finite-element modelling. A parametric study is conducted to assess the role of pile–soil adhesion, group size and pile spacing on group capacity and corresponding failure mechanisms. Results from the finite-element output show that large groups of closely spaced piles exhibit significant

The most commonly used procedure for prediction of the behaviour of laterally loaded piles is the P–y curve formulation, which gives a simple but efficient framework to predict the response of the pile. This framework is limited to a single direction of loading, while there are several situations in which a pile is subjected to lateral loads with varying direction, as for example in the case of wind

This paper discusses the flotation of cables and pipelines that have been trenched using jet trenching during reconsolidation of the seabed soil. Utilising previously published data on the variation of clay strength with liquidity index, it is demonstrated for the first time that, while current industry guidance is appropriate for the low-plasticity clays for which much previous research has been carried

Sands exhibit a directional diversity in shear modulus at small strains, reflecting the anisotropic stiffness behaviour in the structure. In this paper, sample preparation method, particle shape and particle size are considered as parameters to produce samples with various initial fabric. Five preparation methods, namely, air and water pluviation, dry and moist tamping and dry funnel deposition are

This paper presents a field study of obliquely loaded rocking shallow foundations resting on cohesive soil. Lateral snap-back and cyclic loading tests at an oblique angle of 45° with respect to the footing axes were carried out. During the snap-back tests, an initial drift ratio was applied to the deck and then the system was released to enable the free vibration. The cyclic loading consisted of five

The response of floating pile foundations in deep deposits of soft clay is governed by the settlements within the clay deposit surrounding the piles. A long-duration thermal response test (TRT) has been performed to assess the impact of heating and cooling on the geotechnical performance of a vertically loaded slender tubular steel pile in a deep deposit of sensitive clay. The results from the instrumented

The influence of overall particle shape, mean particle size, initial relative density and effective normal stress on the global and local soil–geosynthetic interaction is investigated here through an extensive series of direct shear interface tests between six sands in contact with one multifilament woven geotextile, one non-woven geotextile and one geomembrane. Analysis of the soil–geosynthetic data

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