基于分段步进式弹塑性格构模型的混凝土破坏过程细观模拟

The classically lattice model assumes the local elements behave elastic brittle, neglecting the ductility of the mortar matrix. This leads to the simulated load⁃displacement response more brittle than the realistic. To solve the aforementioned issue, a piece⁃wise approach was introduced to describe the elastic⁃plastic constitutive relation of...

A Semi-micromechanical Framework for Anisotropic Sands

In this paper, a state-dependent semi-micromechanical framework for anisotropic sands is proposed. A simple constitutive model based on critical state theory and bounding surface (BS) plasticity is used to describe idealized micro-level soil behaviour, and a slip theory based multilaminate framework employed to create a link between the micro...

A state-dependent multilaminate constitutive model for anisotropic sands

Experimental studies show that initial fabric and its evolution under different stress paths highly influence soil behaviour. Even though different sample preparation methods create different inherent anisotropies and cause different material responses, the same initial fabric structure under different stress paths also results in different...

Modelling a Cone Penetration Test in Dry Sand using the Material Point Method: A State-Dependent Constitutive Model Approach

The numerical modelling of a cone penetration test (CPT) has long been a challenging task due to the large deformations associated with the penetration of a CPT. Recent developments in advanced numerical methods have shown promising results in overcoming these difficulties by using the Material Point Method (MPM). In this thesis it is researched...

Relating cone penetration resistance to sand state using the material point method

Cone penetration tests (CPTs) can quantitatively inform about the mechanical state of a sand. However, relating measured cone resistance values to sand state requires complex back-analysis of the processes occurring in the soil during the test. This paper provides new evidence of the value added in this area by modern large-deformation...

From cyclic sand ratcheting to tilt accumulation of offshore monopiles: 3D FE modelling using SANISAND-MS

Serviceability criteria for offshore monopiles include the estimation of long-term, permanent tilt under repeated operational loads. In the lack of well-established analysis methods, experimental and numerical research has been carried out in the last decade to support the fundamental understanding of monopile-soil interaction mechanisms, and...

Gas exsolution and gas invasion in peat: Towards a comprehensive modelling framework

Increasing climatic stresses accelerate the degradation of highly organic soils, like peat, by increasing their drying rate above the water table and their decomposition rate under water. Recent experimental studies provide evidence of the consequences of these processes on the hydro-mechanical properties of peat. However, modelling the...

Finite-element modelling of laterally loaded piles in a dense marine sand at Dunkirk

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...

Prediction of oedometer terminal densities through a memory-enhanced cyclic model for sand

Predicting the cyclic response of soils is still challenging in many geotechnical applications. In this area, the continual efforts on the constitutive modelling of cyclic sand behaviour demand new and reliable dataset for model validation - even more so for loading conditions involving numerous loading cycles ('high-cyclic' loading). This paper...

Modelling the cyclic ratcheting of sands through memory-enhanced bounding surface plasticity

The modelling and simulation of cyclic sand ratcheting is tackled by means of a plasticity model formulated within the well-known critical state, bounding surface SANISAND framework. For this purpose, a third locus – termed the ‘memory surface’ – is cast into the constitutive formulation, so as to phenomenologically capture micro-mechanical,...

Computing the near-wall region in gas micro- and nanofluidics: Critical Knudsen layer phenomena

In order to capture critical near-wall phenomena in gas micro- and nanoflows within conventional CFD codes, we present scaled Navier-Stokes-Fourier (NSF) constitutive relations. Our scaling is mathematically equivalent to applying an 'effective' viscosity to the original constitutive relations. An expression for this 'effective' transport...