• 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 macro-element for integrated time domain analyses representing bucket foundations for offshore wind turbines 

      Skau, Kristoffer Skjolden; Grimstad, Gustav; Page, Ana M.; Eiksund, Gudmund Reidar; Jostad, Hans Petter (Peer reviewed; Journal article, 2018)
      The paper presents a macro-element model for bucket foundations to be used in integrated time domain analyses of offshore wind turbines. The macro-element has been formulated in the multi-surface plasticity framework, and ...
    • A macro-element model for multidirectional cyclic lateral loading of monopiles in clay 

      Page, Ana M.; Grimstad, Gustav; Eiksund, Gudmund Reidar; Jostad, Hans Petter (Journal article; Peer reviewed, 2018)
      This paper investigates numerically the impact of multidirectional cyclic loads on the response of a monopile in clay supporting an offshore wind turbine (OWT). The results indicate that multidirectional loading modifies ...
    • A macro-element pile foundation model for integrated analyses of monopilebased offshore wind turbines 

      Page, Ana M.; Grimstad, Gustav; Eiksund, Gudmund Reidar; Jostad, Hans Petter (Journal article; Peer reviewed, 2018)
      The design of OWTs relies on integrated load analyses tools that simulate the response of the entire OWT (including the rotor-nacelle assembly, support structure and foundation) under combined aerodynamic and hydrodynamic ...
    • A New Foundation Model for Integrated Analyses of Monopile-based Offshore Wind Turbines 

      Page, Ana M.; Skau, Kristoffer Skjolden; Jostad, Hans Petter; Eiksund, Gudmund Reidar (Peer reviewed; Journal article, 2017)
      Offshore wind turbines are highly dynamic and tightly coupled systems subjected to variable cyclic loads. Designing and optimizing the support structure is a complex task, where several load scenarios have to be analysed ...
    • A numerical study of capacity and stiffness of circular skirted foundations in clay subjected to combined static and cyclic general loading 

      Skau, Kristoffer Skjolden; Chen, Ying; Jostad, Hans Petter (Peer reviewed; Journal article, 2017)
      Skirted foundations have been widely applied as offshore foundations for several decades. In design, the use of failure envelopes is convenient for assessing stability under combined loading. A large number of studies on ...
    • A procedure for predicting the permanent rotation of monopiles in sand supporting offshore wind turbines 

      Page, Ana M.; Klinkvort, Rasmus Tofte; Bayton, Steven; Zhang, Youhu; Jostad, Hans Petter (Peer reviewed; Journal article, 2020)
      Foundations for Offshore Wind Turbines (OWTs) are designed following the limit state philosophy. One of the considered states is the Serviceability Limit State (SLS), which verifies that the permanent rotation of the ...
    • 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 shear strength model for cyclic accumulated plastic strain of overconsolidated clay 

      Cai, Fang; Eiksund, Gudmund Reidar; Grimstad, Gustav; Jostad, Hans Petter (Journal article, 2014)
      Many geotechnical problems involve calculation of the permanent deformation of overconsolidated clay under undrained cyclic loading. There are many existing methods in the literature which have been made for predicting ...
    • Assessment of the impact of pile driving on slope stability 

      Attari, Yeganeh; Eiksund, Gudmund Reidar; Jostad, Hans Petter (Lecture, 2023)
      Driving piles near slopes can be challenging in terms of temporarily reducing slope stability, specifically in the presence of sensitive clay or lenses of sand and silt in the ground. There is currently no standard method ...
    • Correction factors for undrained LE analyses of sensitive clays 

      Fornes, Petter; Jostad, Hans Petter (Chapter, 2017)
      Reliable prediction of landslide triggering threshold and landslide run-out distance is essential for hazard risk assessment. The paper focuses on studying slides in sensitive clays, which represent a major geohazard in ...
    • 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 ...
    • Design considerations of suction caisson foundations for offshore wind turbines in Southern China 

      Liu, Bo; Zhang, Youhu; Ma, Zhaorong; Andersen, Knut H; Jostad, Hans Petter; Liu, Donghua; Pei, Aiguo (Peer reviewed; Journal article, 2020)
      Suction caisson foundations are increasingly considered as a foundation solution for offshore wind farm development in China. This paper outlines the design considerations for developing a suction caisson supported jacket ...
    • Drainage conditions around monopiles in sand 

      Li, Shuzhao; Zhang, Youhu; Jostad, Hans Petter (Journal article; Peer reviewed, 2019)
      Large diameter monopiles are typical foundation solutions for offshore wind turbines. In design of the monopile foundations in sand, it is necessary to understand the drainage conditions of the foundation soil under the ...
    • Effects of fines content in numerical simulation of CPTu in silty sands 

      Nagula, Sparsha Sinduri; Jostad, Hans Petter; Blaker, Øyvind (Lecture, 2023)
      The Cone Penetration Test (CPTu) does not measure soil properties directly; rather, it measures cone resistance, sleeve friction and pore water pressure, that correlated with laboratory test data, allow estimation of soil ...
    • Evaluation of Pile Driving Effects on Slope Stability in Clay 

      Attari, Yeganeh; Jostad, Hans Petter; Grimstad, Gustav; Eiksund, Gudmund Reidar (Peer reviewed; Journal article, 2023)
    • 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 ...
    • GeoSuite Assistance for the Calculation of Settlement 

      Lacasse, Suzanne; Jostad, Hans Petter; Kim, Yunhee; Liu, Zhongqiang; Sandven, Rolf Birger (Chapter, 2016)
      As part of the development of the Norwegian-Swedish software GeoSuite, a module with geoassistance was developed and implemented. The paper describes this user-assistance, called "Wizard", helping the user with 1D, 2D and ...