Shelly carbonate sands proliferate in regions of the world where construction offshore structures is high demand. These structurally weak have intra-granular voids and complex angular grain shapes. To improve understanding mechanical properties material, a detailed morphological quantification required. This paper presents three-dimensional characterisation morphology shelly based on analyses X-ray computed tomography images. Two from Persian Gulf with distinct grading were investigated. An...

A number of potential offshore wind turbines in China will be constructed sandy silt seabeds, and the mono-caisson foundation is an important choice for these turbines. program large-scale model tests on suction installation lateral loading caisson foundations saturated were carried out a large soil tank at Zhejiang University. Test results resistance during show that seepage effect limited silt, required to penetrate can well predicted based sleeve friction cone penetration tests. The...

This research introduces the development of a sequential limit analysis (SLA) method in OPTUM. The plane-strain capability original SLA has been extended to encompass both and axis-symmetric problems, usability expanded broader spectrum users. Moreover, refinements addressing nodal velocities during soil collapse under gravity, specifically scenarios featuring stiff berm leading slope instability, have implemented, enable proper modelling more extreme conditions complex model geometries. A...

Recently, tetrapod piled jacket (TPJ) foundations have shown considerable promise in offshore developments, due to the increases power capacity and water depth for wind turbines. This paper presents a set of centrifuge tests look into lateral loading behaviour TPJ sand, with overall load–displacement responses foundation as well soil resistance internal forces on or within individual piles being examined carefully. Test results show that back-row are more likely be pulled out when is loaded...

Mono-pile foundations have been widely used for offshore wind turbines principally due to their convenient construction and cost-effective nature. So far, little attention has paid large diameter "semi-rigid" piles that distinct behaviours from flexible or ideally rigid piles. This paper presents a series of centrifuge model tests study the deforming bearing characteristics 5.9 dia. semi-rigid pile under lateral loadings in kaolin clay. For monotonic loading, modified p–y curve analysis...

Summary This paper introduces sequential limit analysis (SLA) as a method for modelling large plastic deformations of purely cohesive materials such undrained clay. The involves solving series consecutive small‐deformation collapse problems using finite element analysis, thus ensuring high levels accuracy, efficiency, and robustness. techniques needed to develop an SLA implementation two‐dimensional (plane strain) are described in detail, including model geometry updating routines, treatment...

This paper describes a program of centrifuge model tests on the uplift behaviour suction caisson foundations. The parameters considered were loading rate, diameter (D), soil strength profile, and type footing (i.e., mono-caisson tetra-caissons group). responses examined in terms total resistance, beneath lid, vertical displacements at surface. There exists critical displacement, approximately 0.02D 0.01D for groups, respectively, which turning point can be identified load–displacement curve....

This paper presents a program of centrifuge model tests (100g) on the monotonic and cyclic lateral loading behavior monopiles. The diameter burial depth pile were 59 550 mm, respectively, soil used was Fujian sand with relative density 70%. During loading, linear relation between resistance deflection observed, slope increasing linearly depth. For sample in this study, rate had surprisingly weakening effect pile–soil interaction. confirmed by development positive excess pore pressure (EPP)...

A newly developed sequential limit analysis (SLA) technique is used to perform large-displacement numerical simulations relevant thermally induced lateral buckling of untrenched subsea pipelines. rigid plane-strain pipe segment, partially embedded in undrained clay, subjected cyclic displacements with amplitudes up eight diameters. constant vertical dead load applied the during each sweep, but some analyses this varied from one sweep next. The SLA method directly models evolution soil...

A program of centrifuge model tests conducted on the cyclic lateral behavior a tetrapod piled jacket (TPJ) foundation for offshore wind turbines (OWTs) in medium dense sand was reported. The key parameters investigated were loading direction, load amplitude, and type (i.e., one- or two-way loading) terms overall response TPJ more detailed pile-soil interaction. Under small- moderate-amplitude loads, that is, 20% 40% bearing capacity, respectively, along diagonal direction had pronounced...

T-bar penetrometers are commonly used for the measurements of undrained strength profiles clay (e.g. intact shear strength, sensitivity, ductility). The adoption a constant resistance factor in absence full-flow failure mechanism, coupled with strain-softening effect, usually leads to considerable underestimation soil within depth up several diameters. This paper presents numerical investigation into vertical penetration behaviour using sequential limit analysis (SLA) technique. is...

This paper details a programme of centrifuge tests (100g) on the monotonic and cyclic lateral behaviour large-diameter semi-rigid monopiles in kaolin clay. Piles different diameters were used, with maximum prototype value 5·9 m. The pile–soil interaction was investigated terms overall load–displacement behaviour, distribution bending moment pile deflection, p–y curves excess pore pressure response. For loading, procedures developed to fit obtained from soil properties using hyperbolic...

Summary The engineering applications of energy piles, geological radioactive waste disposals, and mining wells geothermal petroleum are usually associated with strong coupled behaviour consolidation heat flow. This paper aims to present an efficient precise integration technique (PIT) for the analysis such within layered saturated soils surrounding cylindrical sources (ie, a cross section as point, ring, or disc). Each soil layer, together its embedded part source, is divided into 2 N layer...

Offshore pipelines are often laid directly on the seabed, particularly in deep water. Cyclic changes temperature and pressure of pipe contents can lead to cyclic growth contraction (planned) lateral buckles. This results severe plastic deformation near-surface soil as it is progressively scraped away accumulated into berms by sweeping motion pipe. Quantifying resistance offered important design, notably for fatigue calculations. paper presents a new computational approach modelling pipe–soil...