Browsing Norwegian Geotechnical Institute (NGI) Digital Archive by Author "Sivasithamparam, Nallathamby"

3D FE tool for time dependent settlement predictions

Jostad, Hans Petter; Sivasithamparam, Nallathamby; Woldeselassie, B.H.; Lacasse, Suzanne (Chapter, 2016)

A newly developed calculation tool for fully coupled general 3D finite element consolidation analyses is presented. The development has been part of an ongoing Research and Development project called GeoFuture and the tool ...

3D stability analyses of Skjeggestad landslide

Jostad, Hans Petter; Sivasithamparam, Nallathamby; Lacasse, Suzanne; Degago, Samson Abate; Le, Thi Minh Hue; Giese, Steffen; Rosenquist af Åkershult, Anders; Johansen, Torbjørn; Aabøe, Roald (Peer reviewed; Journal article, 2021)

In 2015, a sudden landslide caused the failure of one of the pillars supporting the southern lanes of the Skjeggestad Bridge near Mofjellbekken on Expressway E18. The transportation corridor was closed to traffic for 17 ...

A Constitutive Model for Soft Clays Incorporating Elastic and Plastic Cross-Anisotropy

Castro, Jorge; Sivasithamparam, Nallathamby (Peer reviewed; Journal article, 2017)

Natural clays exhibit a significant degree of anisotropy in their fabric, which initially is derived from the shape of the clay platelets, deposition process and one-dimensional consolidation. Various authors have proposed ...

A Framework for Versatile Shape of Yield Surfaces for Structured Aniso-tropic Soft Soils

Sivasithamparam, Nallathamby; Castro, Jorge (Chapter, 2016)

A framework based on logarithmic contractancy is proposed to produce versatile shapes of yield surfaces for structured anisotropic clays. The recently proposed constitutive model (E-SCLAY1S) is an extension of existing ...

Accounting for effects of cyclic loading in design of offshore wind turbine foundations

Jostad, Hans Petter; Liu, Haoyuan; Sivasithamparam, Nallathamby (Lecture, 2023)

In the design of foundations for offshore structures, it is generally important and required to consider the effects of cyclic loading caused by waves and wind. Therefore, NGI has developed a framework since the early 1970s ...

An anisotropic elastoplastic model for soft clays based on logarithmic contractancy

Sivasithamparam, Nallathamby; Castro, Jorge (Journal article, 2015)

A new constitutive model for soft structured clays is developed based on an existing model called S-CLAY1S, which is a Cam clay type model that accounts for anisotropy and destructuration. The new model (E-SCLAY1S) uses ...

Back-Calculation of Element Tests with a Rate Dependent Soft Soil Model

Yannie, Jorge; Sivasithamparam, Nallathamby (Chapter, 2016)

It is well known that soft clays are geo-materials with properties such as fabric, bonding and rate-dependency. The response observed when modelling complex boundary value problems will depend on the ability of the soil ...

Creep of geomaterials – some finding from the EU project CREEP

Grimstad, Gustav; Karstunen, Minna; Jostad, Hans Petter; Sivasithamparam, Nallathamby; Mehli, Magne; Zwanenburg, Cor; Evert, den Haan; Ghoreishian Amiri, Seyed Ali; Boumezerane, Djamalddine; Kadivar, Mehdi; Haji Ashrafi, Mohammad Ali; Rønningen, Jon A. (Peer reviewed; Journal article, 2017)

Cyclic Capacity of Monopiles in Sand under Partially Drained Conditions: A Numerical Approach

Jostad, Hans Petter; Liu, Haoyuan; Sivasithamparam, Nallathamby; Ragni, Raffaele (Journal article; Peer reviewed, 2022)

Cyclic loading of saturated sand under partially drained conditions may lead to accumulated strains, pore pressure buildup, and consequently reduced effective stress, stiffness, and shear strength. This will affect the ...

Discussion: Undrained cylindrical cavity expansion in anisotropic critical state soils

Chen, Shengli; Liu, Kai; Castro, Jorge; Sivasithamparam, Nallathamby (Journal article; Peer reviewed, 2018)

Evaluation of soil models for improved design of offshore wind turbine foundations in dense sand

Jostad, Hans Petter; Dahl, Birgitte Misund; Page, Ana M.; Sivasithamparam, Nallathamby; Sturm, Hendrik (Peer reviewed; Journal article, 2020)

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 ...

Impact of cyclic strain accumulation on the tilting behaviour of monopiles in sand: An assessment of the Miner's rule based on SANISAND-MS 3D FE modelling

Liu, Haoyuan; Pisanò, Federico; Jostad, Hans Petter; Sivasithamparam, Nallathamby (Peer reviewed; Journal article, 2022)

Load history idealisation effects for design of monopiles in clay

Liu, Haoyuan; Sivasithamparam, Nallathamby; Suzuki, Yusuke; Jostad, Hans Petter (Peer reviewed; Journal article, 2022)

Modelling creep behaviour of anisotropic soft soils

Sivasithamparam, Nallathamby; Karstunen, Minna; Bonnier, Paul (Journal article, 2015)

This paper presents a three dimensional constitutive model that describes the creep behaviour of natural clays with anisotropic stress–strain response, focussing on robust model implementation. Creep is formulated using ...

On the stress update algorithm of an advanced critical state elasto-plastic model and the effect of yield function equation

Rezania, Mohammad; Sivasithamparam, Nallathamby; Nezhad, Mohaddeseh Mousavi (Journal article, 2014)

This paper investigates the computational performance of S-CLAY1S constitutive model by varying its yield function equation. S-CLAY1S is an advanced anisotropic elasto-plastic model that has been developed based on the ...