The document discusses the foundation engineering assessment for installing the world's largest jack-up rig offshore Norway. Based on site investigations, the soil conditions varied across the site and consisted of bedrock overlaid by soft silt/clay and a shallow sand layer. Conventional and finite element analyses proposed constructing sand banks to provide a stable foundation. Three-dimensional finite element modeling of the integrated jack-up structure, skirted spudcan foundations, and soil was used to determine the optimal sand bank geometry. The modeling showed structural forces would remain acceptable during installation, preloading, and storm conditions. The rig was successfully installed, validating the engineering predictions.
This document summarizes a study analyzing the interaction between a jack-up rig's spudcans and an offshore pipeline during installation of the rig. Finite element modeling was used to evaluate soil deformation around the spudcan and at the pipeline. Both virgin soil profiles and modified profiles accounting for consolidation from a previous rig installation were considered. The results showed significant potential soil uplift near the pipeline. The modified soil profiles, with increased clay strength from consolidation, reduced predicted uplift. Overall, the study aimed to assess pipeline stability during the planned rig installation.
This document provides a review of published and unpublished data on the field performance of stone columns used to improve soft cohesive soils like clays and silts. It develops a new database of settlement improvement factors from case studies and analyzes aspects of stone column performance where sufficient data is available. Key findings relate to pore pressure changes and total stresses resulting from column installation and loading. The review aims to provide practitioners with a useful reference when designing stone column ground improvement schemes in soft soils.
This document discusses site investigation and selection of dam types. It outlines the functional and technical requirements that must be satisfied for a dam site, including hydrological characteristics, available head and storage, and geological/geotechnical properties. A coordinated team of specialists is needed to properly evaluate engineering, geological, and environmental factors. Site investigations involve collecting physical, topographic, geological, hydrological, and materials data to assess suitability and inform dam design. Key considerations for site selection include catchment characteristics, foundation conditions, material availability, and project development needs.
1. A landslide occurred in mixed soft Carboniferous-Permian rock after excavation and heavy rainfall on a motorway construction site. Detailed investigations were conducted to characterize the rock mass and understand the failure mechanism.
2. Laboratory tests on rock samples and in situ measurements were used to determine strength and deformability parameters of the three rock layers. Back analysis using numerical modeling was performed at micro, sample, and slope scales.
3. Monitoring during construction showed the landslide slowly creeping. An anchored pile wall and drainage system were successfully used to stabilize the landslide to allow restoration work.
"A Review of the Settlement of Stone Columns in Compressible Soils"Remedy Geotechnics Ltd
This document summarizes a review of stone column settlement performance in compressible soils. It presents a new database of settlement improvement factors (n) calculated from over 20 case studies of stone column-improved ground. The database shows that n, a measure of settlement reduction, is generally predicted well by Priebe's improvement factor method. Additionally, n reflects the construction method, with dry bottom feed columns consistently outperforming other methods. The discussion considers how the stone column friction angle and construction technique affect settlement.
This document provides an overview of stone columns, which are columns of compacted aggregate installed in soft soils to improve their load-bearing capacity and reduce settlement. Stone columns function by transferring load to the stiffer column material, allowing drainage of pore water pressures. They are installed using ramming or vibro-replacement techniques. Failure typically occurs through bulging of the column into the surrounding soil. A case study demonstrates that a highway embankment treated with stone columns at 2m spacing experienced 25% less settlement than untreated ground.
This document summarizes a study analyzing the interaction between a jack-up rig's spudcans and an offshore pipeline during installation of the rig. Finite element modeling was used to evaluate soil deformation around the spudcan and at the pipeline. Both virgin soil profiles and modified profiles accounting for consolidation from a previous rig installation were considered. The results showed significant potential soil uplift near the pipeline. The modified soil profiles, with increased clay strength from consolidation, reduced predicted uplift. Overall, the study aimed to assess pipeline stability during the planned rig installation.
This document provides a review of published and unpublished data on the field performance of stone columns used to improve soft cohesive soils like clays and silts. It develops a new database of settlement improvement factors from case studies and analyzes aspects of stone column performance where sufficient data is available. Key findings relate to pore pressure changes and total stresses resulting from column installation and loading. The review aims to provide practitioners with a useful reference when designing stone column ground improvement schemes in soft soils.
This document discusses site investigation and selection of dam types. It outlines the functional and technical requirements that must be satisfied for a dam site, including hydrological characteristics, available head and storage, and geological/geotechnical properties. A coordinated team of specialists is needed to properly evaluate engineering, geological, and environmental factors. Site investigations involve collecting physical, topographic, geological, hydrological, and materials data to assess suitability and inform dam design. Key considerations for site selection include catchment characteristics, foundation conditions, material availability, and project development needs.
1. A landslide occurred in mixed soft Carboniferous-Permian rock after excavation and heavy rainfall on a motorway construction site. Detailed investigations were conducted to characterize the rock mass and understand the failure mechanism.
2. Laboratory tests on rock samples and in situ measurements were used to determine strength and deformability parameters of the three rock layers. Back analysis using numerical modeling was performed at micro, sample, and slope scales.
3. Monitoring during construction showed the landslide slowly creeping. An anchored pile wall and drainage system were successfully used to stabilize the landslide to allow restoration work.
"A Review of the Settlement of Stone Columns in Compressible Soils"Remedy Geotechnics Ltd
This document summarizes a review of stone column settlement performance in compressible soils. It presents a new database of settlement improvement factors (n) calculated from over 20 case studies of stone column-improved ground. The database shows that n, a measure of settlement reduction, is generally predicted well by Priebe's improvement factor method. Additionally, n reflects the construction method, with dry bottom feed columns consistently outperforming other methods. The discussion considers how the stone column friction angle and construction technique affect settlement.
This document provides an overview of stone columns, which are columns of compacted aggregate installed in soft soils to improve their load-bearing capacity and reduce settlement. Stone columns function by transferring load to the stiffer column material, allowing drainage of pore water pressures. They are installed using ramming or vibro-replacement techniques. Failure typically occurs through bulging of the column into the surrounding soil. A case study demonstrates that a highway embankment treated with stone columns at 2m spacing experienced 25% less settlement than untreated ground.
This document discusses the seismic design of foundations for the Rion Antirion Bridge in Greece. It describes the challenging soil and seismic conditions at the site, which required innovative foundation design. The foundations consist of large diameter caissons resting on top of reinforced natural ground, with steel tubular inclusions driven into the soil to increase its strength. Three of the four bridge piers use this reinforced foundation solution, while the fourth pier's caisson rests directly on a thick gravel layer without inclusions. The document outlines the design process and considerations, which aimed to ensure the foundations could adequately resist the large earthquake and ship impact loads expected at the seismically active site with poor soil conditions.
A STUDY ON EFFECTS OF GEOSYNTHETIC ENCASEMENT ON FLOATING STONE COLUMNIAEME Publication
1) The document presents a study on the effects of geosynthetic encasement on floating stone columns used to improve soft soil.
2) Laboratory model tests were conducted using a unit cell approach to simulate single stone columns installed in soft clay. Four types of geosynthetic materials were used as encasement for the stone columns.
3) Load-settlement tests were performed on stone columns with and without geosynthetic encasement to analyze the effects of reinforcement type on the load-carrying capacity and settlement behavior of floating stone columns installed in soft clay.
The document provides an overview of geotechnical engineering and the typical components and process involved in a geotechnical engineering report and project. It discusses the four main components of field exploration, laboratory testing, findings and recommendations, and additional studies. It then goes into more detail about specific sections that would be included in a geotechnical report such as site conditions, field exploration methods, laboratory testing, engineering recommendations, earthwork recommendations, and construction observation services.
The Rion Antirion bridge in Greece connects the Peloponnese peninsula to the mainland across the Gulf of Corinth. Its foundations had to withstand severe environmental conditions including weak soils, earthquakes up to magnitude 7.0, and long-term tectonic movements. The innovative foundation concept adopted reinforced the natural ground with steel tubular piles and included a gravel layer between the piles and foundation raft. This provided capacity to resist the large seismic forces while minimizing differential settlement hazards. Extensive site investigations characterized the poor soil properties to ensure compatible design of seismic demand and foundation capacity.
This document discusses the importance of engineering geology in dam construction. There are three main types of dams - arc or buttress dams, gravity dams, and embankment dams - which experience different forces. Proper geological investigations are required to ensure the stability and safety of the dam foundation, the water-tightness of the reservoir, and slope stability. Preliminary geological investigations include topographical studies, reservoir location analysis, petrology studies, structural geology studies, and examining foundation conditions. Detailed investigations involve making a detailed geological map, studying rock types, structures, seismic data, and interpreting core drill samples to understand the engineering geological properties of the area.
Ground Improvement by Vibro Stone ColumnsDesh Sonyok
Vibro replacement stone column is one of the widely used soil improvement technique to improve the settlement characteristics, bearing capacity and mitigate the liquefaction issues of the soft soil. In this paper, improvement of the settlement characteristics of the soft soil is considered for the analysis based on the available case histories. A settlement estimation method proposed by Preibe (1995) is verified quantitatively. Finally, an analytical solution for settlement of soft ground for the stone column design is proposed. The proposed method of calculating settlement is based on the basic concept of composite material and soil mechanics. However, the result of this preliminary work is yet to validate numerically and in the field. Detailed research in future is necessary to check its validity and applicability
The document discusses the objectives and methods of geotechnical investigations for infrastructure projects. It explains that geotechnical investigations are needed to determine the engineering properties and characteristics of soil and rock in order to design foundations, embankments, and structures. The investigations include site reconnaissance, exploratory drilling or digging, laboratory testing of soil samples, and analysis of soil properties including bearing capacity, moisture content, swelling, and shear strength. The results are used to design foundations and recommend construction parameters.
This document provides information about a soil mechanics course including the course code, class details, textbooks, evaluation methods, instructor details, course objectives, syllabus, and exam schedule. The key points are:
1) The course covers soil properties, behavior, testing and applications in geotechnical engineering.
2) The instructor has a PhD from Northwestern University and experience in construction and consulting.
3) Evaluation includes quizzes, midterms, and a final exam. The syllabus covers topics like soil composition, permeability, stress distribution, consolidation, and shear strength.
Somnath soni (iit ism) dhanbad presentation vphepSomnath Soni
The document provides details about the Vishnugad Pipalkoti Hydro Electric Project (VPHEP) being constructed in Chamoli district, Uttarakhand. It includes construction of a 65m high diversion dam and underground powerhouse complex. A study was conducted to determine the Rock Mass Rating (RMR) of the rock mass to define appropriate rock support systems for the tunnels. Based on the RMR classification and characteristics of the rock mass, various support systems like rock bolting, steel fibre reinforced shotcrete, steel ribs and lattice girders have been proposed. Joint data was also collected and 3D geological mapping was conducted for future reference.
The document summarizes the design and construction of the foundations for the Rion Antirion Bridge in Greece. An innovative foundation concept was adopted using steel tubular piles driven into the seabed to reinforce the soil, with a gravel layer between the piles and the concrete caisson foundation. This concept provided seismic capacity and minimized differential settlement risks. Close cooperation between designers, contractors, and reviewers was essential to developing and implementing this challenging foundation solution.
124
مبادرة
#تواصل_تطوير
المحاضرة ال 124 من المبادرة مع
دكتور/ محمد الحسين
بعنوان
المركبات البوليمرية الجيوتقنية و تطبيقاتها في الهندسة المدنية
Geosynthetics in Civil Engineering (Multifunctional uses of geosynthetics in civil engineering)
التاسعة مساء توقيت القاهرة
العاشرة. مساء توقيت مكة المكرمة
السبت 28 أغسطس 2021
وذلك عبر تطبيق زووم
https://us02web.zoom.us/meeting/register/tZwvdeiurjwjHdKFHkNf1hWghC8-OT7ZB2lZ
علما ان هناك بث مباشر للمحاضرة على القنوات الخاصة بجمعية المهندسين المصريين
ونأمل أن نوفق في تقديم ما ينفع المهندس ومهمة الهندسة في عالمنا العربي
والله الموفق
للتواصل مع إدارة المبادرة عبر قناة التليجرام
https://t.me/EEAKSA
ومتابعة المبادرة والبث المباشر عبر نوافذنا المختلفة
رابط اللينكدان والمكتبة الالكترونية
https://www.linkedin.com/company/eeaksa-egyptian-engineers-association/
رابط قناة التويتر
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رابط قناة اليوتيوب
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رابط التسجيل العام للمحاضرات
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ملحوظة : توجد شهادات حضور مجانية لمن يسجل فى رابط التقيم اخر المحاضرة.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Site investigation plays a crucial role in identifying adverse ground conditions that can jeopardize tunnel projects and cause delays or accidents during construction. Key aspects of site investigation include desk studies, walkover surveys, subsurface exploration techniques like drilling and cone penetration tests, and geophysical methods. Case studies of past tunneling accidents demonstrate how lack of knowledge about geological conditions from inadequate site investigation can lead to failures like collapses from groundwater ingress or unstable rock masses. A multistage site investigation employing various techniques can best acquire information to reduce risks from unexpected ground conditions during tunnel excavation.
The document summarizes the stages of a site investigation which includes a desk study, site reconnaissance, detailed exploration and sampling, field/in-situ testing, and laboratory testing. The objectives are to assess suitability, enable adequate design, plan construction, determine ground changes, and document the investigation in a report. Site investigations involve exploring ground conditions through methods like boreholes, trial pits, and geophysical surveys to inform engineering design decisions.
1. Careful geological studies are important for selecting dam and reservoir sites to reduce costs and ensure safety and stability.
2. Ideal dam sites have narrow river valleys, competent bedrock like igneous or metamorphic rock near the surface, and favorable geological structures like horizontal or mildly tilted strata.
3. Faults and steeply dipping or folded strata are less desirable as they can compromise the stability and impermeability of the foundation rocks.
IRJET- Investigations of Granular Pile Anchors in Granulated Soil Subject...IRJET Journal
This document presents a numerical study investigating the uplift capacity of granular pile anchors (GPA) in granulated soil. The study used PLAXIS 3D software to model GPA systems with varying pile diameters, spans, and soil properties. It found that as the pile diameter, span, soil friction angle, and relative density increased, the uplift capacity of the GPA also increased to varying degrees. However, increasing the span to diameter ratio beyond 10 did not significantly affect the load sharing. The study aims to understand how changing characteristics of the pile and surrounding soil impact the resistance of GPA systems to uplifting forces.
The document summarizes the design and construction of the foundations for the Rion Antirion Bridge in Greece. Key points:
- The foundations had to withstand severe environmental conditions like weak soil, earthquakes, and tectonic movements. An innovative concept was adopted using large diameter caissons resting on reinforced natural ground with steel pipe inclusions.
- Under each caisson, 150-200 steel pipe inclusions 2m in diameter were driven into the soil in a 7m grid to reinforce it. A 2.8m thick gravel layer separated the caisson from the inclusions.
- This concept provided capacity design by allowing sliding at the gravel interface during large seismic forces, limiting forces on the super
This document discusses the seismic design of foundations for the Rion Antirion Bridge in Greece. It describes the challenging soil and seismic conditions at the site, which required innovative foundation design. The foundations consist of large diameter caissons resting on top of reinforced natural ground, with steel tubular inclusions driven into the soil to increase its strength. Three of the four bridge piers use this reinforced foundation solution, while the fourth pier's caisson rests directly on a thick gravel layer without inclusions. The document outlines the design process and considerations, which aimed to ensure the foundations could adequately resist the large earthquake and ship impact loads expected at the seismically active site with poor soil conditions.
A STUDY ON EFFECTS OF GEOSYNTHETIC ENCASEMENT ON FLOATING STONE COLUMNIAEME Publication
1) The document presents a study on the effects of geosynthetic encasement on floating stone columns used to improve soft soil.
2) Laboratory model tests were conducted using a unit cell approach to simulate single stone columns installed in soft clay. Four types of geosynthetic materials were used as encasement for the stone columns.
3) Load-settlement tests were performed on stone columns with and without geosynthetic encasement to analyze the effects of reinforcement type on the load-carrying capacity and settlement behavior of floating stone columns installed in soft clay.
The document provides an overview of geotechnical engineering and the typical components and process involved in a geotechnical engineering report and project. It discusses the four main components of field exploration, laboratory testing, findings and recommendations, and additional studies. It then goes into more detail about specific sections that would be included in a geotechnical report such as site conditions, field exploration methods, laboratory testing, engineering recommendations, earthwork recommendations, and construction observation services.
The Rion Antirion bridge in Greece connects the Peloponnese peninsula to the mainland across the Gulf of Corinth. Its foundations had to withstand severe environmental conditions including weak soils, earthquakes up to magnitude 7.0, and long-term tectonic movements. The innovative foundation concept adopted reinforced the natural ground with steel tubular piles and included a gravel layer between the piles and foundation raft. This provided capacity to resist the large seismic forces while minimizing differential settlement hazards. Extensive site investigations characterized the poor soil properties to ensure compatible design of seismic demand and foundation capacity.
This document discusses the importance of engineering geology in dam construction. There are three main types of dams - arc or buttress dams, gravity dams, and embankment dams - which experience different forces. Proper geological investigations are required to ensure the stability and safety of the dam foundation, the water-tightness of the reservoir, and slope stability. Preliminary geological investigations include topographical studies, reservoir location analysis, petrology studies, structural geology studies, and examining foundation conditions. Detailed investigations involve making a detailed geological map, studying rock types, structures, seismic data, and interpreting core drill samples to understand the engineering geological properties of the area.
Ground Improvement by Vibro Stone ColumnsDesh Sonyok
Vibro replacement stone column is one of the widely used soil improvement technique to improve the settlement characteristics, bearing capacity and mitigate the liquefaction issues of the soft soil. In this paper, improvement of the settlement characteristics of the soft soil is considered for the analysis based on the available case histories. A settlement estimation method proposed by Preibe (1995) is verified quantitatively. Finally, an analytical solution for settlement of soft ground for the stone column design is proposed. The proposed method of calculating settlement is based on the basic concept of composite material and soil mechanics. However, the result of this preliminary work is yet to validate numerically and in the field. Detailed research in future is necessary to check its validity and applicability
The document discusses the objectives and methods of geotechnical investigations for infrastructure projects. It explains that geotechnical investigations are needed to determine the engineering properties and characteristics of soil and rock in order to design foundations, embankments, and structures. The investigations include site reconnaissance, exploratory drilling or digging, laboratory testing of soil samples, and analysis of soil properties including bearing capacity, moisture content, swelling, and shear strength. The results are used to design foundations and recommend construction parameters.
This document provides information about a soil mechanics course including the course code, class details, textbooks, evaluation methods, instructor details, course objectives, syllabus, and exam schedule. The key points are:
1) The course covers soil properties, behavior, testing and applications in geotechnical engineering.
2) The instructor has a PhD from Northwestern University and experience in construction and consulting.
3) Evaluation includes quizzes, midterms, and a final exam. The syllabus covers topics like soil composition, permeability, stress distribution, consolidation, and shear strength.
Somnath soni (iit ism) dhanbad presentation vphepSomnath Soni
The document provides details about the Vishnugad Pipalkoti Hydro Electric Project (VPHEP) being constructed in Chamoli district, Uttarakhand. It includes construction of a 65m high diversion dam and underground powerhouse complex. A study was conducted to determine the Rock Mass Rating (RMR) of the rock mass to define appropriate rock support systems for the tunnels. Based on the RMR classification and characteristics of the rock mass, various support systems like rock bolting, steel fibre reinforced shotcrete, steel ribs and lattice girders have been proposed. Joint data was also collected and 3D geological mapping was conducted for future reference.
The document summarizes the design and construction of the foundations for the Rion Antirion Bridge in Greece. An innovative foundation concept was adopted using steel tubular piles driven into the seabed to reinforce the soil, with a gravel layer between the piles and the concrete caisson foundation. This concept provided seismic capacity and minimized differential settlement risks. Close cooperation between designers, contractors, and reviewers was essential to developing and implementing this challenging foundation solution.
124
مبادرة
#تواصل_تطوير
المحاضرة ال 124 من المبادرة مع
دكتور/ محمد الحسين
بعنوان
المركبات البوليمرية الجيوتقنية و تطبيقاتها في الهندسة المدنية
Geosynthetics in Civil Engineering (Multifunctional uses of geosynthetics in civil engineering)
التاسعة مساء توقيت القاهرة
العاشرة. مساء توقيت مكة المكرمة
السبت 28 أغسطس 2021
وذلك عبر تطبيق زووم
https://us02web.zoom.us/meeting/register/tZwvdeiurjwjHdKFHkNf1hWghC8-OT7ZB2lZ
علما ان هناك بث مباشر للمحاضرة على القنوات الخاصة بجمعية المهندسين المصريين
ونأمل أن نوفق في تقديم ما ينفع المهندس ومهمة الهندسة في عالمنا العربي
والله الموفق
للتواصل مع إدارة المبادرة عبر قناة التليجرام
https://t.me/EEAKSA
ومتابعة المبادرة والبث المباشر عبر نوافذنا المختلفة
رابط اللينكدان والمكتبة الالكترونية
https://www.linkedin.com/company/eeaksa-egyptian-engineers-association/
رابط قناة التويتر
https://twitter.com/eeaksa
رابط قناة الفيسبوك
https://www.facebook.com/EEAKSA
رابط قناة اليوتيوب
https://www.youtube.com/user/EEAchannal
رابط التسجيل العام للمحاضرات
https://forms.gle/vVmw7L187tiATRPw9
ملحوظة : توجد شهادات حضور مجانية لمن يسجل فى رابط التقيم اخر المحاضرة.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Site investigation plays a crucial role in identifying adverse ground conditions that can jeopardize tunnel projects and cause delays or accidents during construction. Key aspects of site investigation include desk studies, walkover surveys, subsurface exploration techniques like drilling and cone penetration tests, and geophysical methods. Case studies of past tunneling accidents demonstrate how lack of knowledge about geological conditions from inadequate site investigation can lead to failures like collapses from groundwater ingress or unstable rock masses. A multistage site investigation employing various techniques can best acquire information to reduce risks from unexpected ground conditions during tunnel excavation.
The document summarizes the stages of a site investigation which includes a desk study, site reconnaissance, detailed exploration and sampling, field/in-situ testing, and laboratory testing. The objectives are to assess suitability, enable adequate design, plan construction, determine ground changes, and document the investigation in a report. Site investigations involve exploring ground conditions through methods like boreholes, trial pits, and geophysical surveys to inform engineering design decisions.
1. Careful geological studies are important for selecting dam and reservoir sites to reduce costs and ensure safety and stability.
2. Ideal dam sites have narrow river valleys, competent bedrock like igneous or metamorphic rock near the surface, and favorable geological structures like horizontal or mildly tilted strata.
3. Faults and steeply dipping or folded strata are less desirable as they can compromise the stability and impermeability of the foundation rocks.
IRJET- Investigations of Granular Pile Anchors in Granulated Soil Subject...IRJET Journal
This document presents a numerical study investigating the uplift capacity of granular pile anchors (GPA) in granulated soil. The study used PLAXIS 3D software to model GPA systems with varying pile diameters, spans, and soil properties. It found that as the pile diameter, span, soil friction angle, and relative density increased, the uplift capacity of the GPA also increased to varying degrees. However, increasing the span to diameter ratio beyond 10 did not significantly affect the load sharing. The study aims to understand how changing characteristics of the pile and surrounding soil impact the resistance of GPA systems to uplifting forces.
The document summarizes the design and construction of the foundations for the Rion Antirion Bridge in Greece. Key points:
- The foundations had to withstand severe environmental conditions like weak soil, earthquakes, and tectonic movements. An innovative concept was adopted using large diameter caissons resting on reinforced natural ground with steel pipe inclusions.
- Under each caisson, 150-200 steel pipe inclusions 2m in diameter were driven into the soil in a 7m grid to reinforce it. A 2.8m thick gravel layer separated the caisson from the inclusions.
- This concept provided capacity design by allowing sliding at the gravel interface during large seismic forces, limiting forces on the super
The document discusses lessons learned from applying a new subdivision standard for jack-up rigs that requires a minimum range of stability after flooding of any single compartment. It was found that stability calculations could unexpectedly terminate before reaching the full range, known as "fading stability curves". This was resolved by returning to fundamental stability principles and developing a new approach using iso-energy contours to visualize the energy required to incline the vessel at different heel and trim combinations. Key findings were that fading stability does not indicate capsizing, and the traditional concept of range of stability is not applicable when such curves occur.
The document discusses the history and importance of chocolate in society. It details how chocolate originated in Mexico and South America, was popularized in Europe after its discovery by the Spanish, and is now widely consumed globally on a daily basis both in its raw cocoa bean form and in products like chocolate bars. Chocolate has become deeply ingrained in many cultures and traditions over centuries.
This document discusses steel wire ropes used in offshore oil and gas exploration. It describes anchor lines, drill lines, pennant lines, and other ropes used for offshore mooring and drilling operations. Anchor lines are robust constructions able to withstand deployment and shifting of drilling units. Drill lines are recommended as 6x19/IWRC constructions for raising and lowering drill pipes. Pennant lines experience severe operating conditions during anchor recovery.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
Guidelines for marine lifting operation noble dentonOFFSHORE VN
1. This document provides guidelines for approving marine lifting operations using floating crane vessels or land-based cranes.
2. It describes Noble Denton's approval process and guidelines for load and safety factors to apply at the design stage.
3. The report also offers comments on practical considerations for managing lifting operations and the information required for approval.
FINITE ELEMENT MODELING AND JACKET LAUCH ANALYSIS USING A BARGEOFFSHORE VN
The document describes a finite element method for numerically simulating the launch of an offshore structure jacket from a barge. Software programs like StruCAD*3D and SACS can be used to model the barge-jacket system and calculate the jacket launch process. The method involves establishing coordinate systems, modeling the barge and jacket geometry, calculating hydrodynamic forces, and solving the equations of motion to obtain the motion of the barge and jacket over time during the different phases of launch. The output provides details on the position, velocity, acceleration and interaction forces acting on the barge-jacket system throughout the simulation.
The document provides an overview of offshore platform design. It discusses the different types of offshore platforms including fixed platforms like jacket structures, gravity platforms, and compliant towers as well as floating platforms like tension leg platforms, semi-submersibles, spars, and FPSOs. It describes the key components of offshore platforms including the topside facilities and underwater structures like pilings and mooring systems. The document also covers topics like naval architecture considerations, structural design and analysis, and installation procedures for offshore platforms.
1) Crosby shackles have the highest design factor in the industry at 6 to 1. Their design ensures strength, ductility, and fatigue properties are met.
2) Crosby shackles are closed die forged which produces consistent dimensions and close tolerance pin holes, improving fatigue life.
3) All Crosby shackle bows and pins are quenched and tempered, enhancing performance in cold temperatures and adverse conditions. This provides properties like strength, ductility, and fatigue resistance.
This document discusses the design of pile groups for settlement at a residential development site with soft soil deposits in South Korea. A pretensioned spun high-strength concrete pile (PHC pile) was proposed as a more economical alternative to the traditionally used steel pipe piles. A comprehensive testing program was conducted including static load tests on instrumented piles. Five methods for calculating pile group settlement were evaluated, with the Unified Design Method selected since it considers ongoing consolidation of soft soils, pile-soil interaction, and the distribution of pile shaft resistance. The analysis of test data was important for understanding factors like strain effects, residual load development, and negative skin friction distribution. Reliable settlement estimation was a key issue for the PHC pile
This document presents a case study on estimating the modulus of subgrade reaction (k-value) for designing raft foundations of multi-story buildings constructed on sandy soil in Dammam, Saudi Arabia. Site investigations including boreholes and plate load tests were conducted. Plate load tests were back analyzed using numerical modeling to validate the soil properties. Different sized foundations were then modeled to estimate k-values. The k-values decreased with increasing foundation size and sometimes differed from values estimated using Terzaghi's equation, highlighting that k-value depends on foundation properties and soil conditions.
PERFORMANCE EVALUATION OF DEEP EXCAVATION UNDER STATIC AND SEISMIC LOAD CONDI...IRJET Journal
The document presents a numerical analysis of a 12m deep excavation supported by an anchored diaphragm wall. A finite element model was created using PLAXIS 2D to model the layered soil stratum and retaining structures. A parametric study was conducted by varying the anchor inclination, surcharge load location, and considering static and dynamic load conditions. The results found that horizontal displacement, bending moment, and shear force in the wall were highest when the surcharge was closest to the excavation line and decreased as the surcharge moved farther away. Dynamic loading produced greater wall response compared to static loading.
This document summarizes research on the bearing capacity of sand overlying clay with a strip footing. Laboratory and numerical experiments were conducted to investigate the behavior and failure modes. Previous analytical methods for calculating bearing capacity are reviewed. The experimental setup involved testing isolated strip footings on a dense or loose sand layer overlying clay. Tests varied the sand layer thickness to footing width ratio and soil properties. Results presented failure modes, load-settlement curves, and relationships between bearing capacity and soil parameters.
The document summarizes the design and construction of the foundations for the Rion Antirion Bridge in Greece. Key points:
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1. JACK-UP RIG FOUNDATION DESIGN
APPLYING 3D FE STRUCTURE - SOIL -
INTERACTION MODELLING
L KELLEZI
GEO - Danish Geotechnical Institute
1 Maglebjergvej, DK 2800 Kgs. Lyngby, Denmark
G KUDSK
Maersk Contractors
Esplanaden 50, DK 1098 Copenhagen K, Denmark
H HOFSTEDE
Marine Structure Consultants (MSC)
Karel Doormanweg 66, 3100 AR Schiedam, Netherlands
SUMMARY: The foundation engineering assessment for the world’s largest
jack-up rig installed offshore Norway is carried out. Based on the site survey
and soil investigation data the soil conditions vary accross the site and consist
of bedrock overlied by very soft silt / clay and a shallow layer of seabed sand.
From the conventional and finite element analyses an engineering solution
comprizing construction of sand banks was proposed. The final geometry of
the banks is determined based on the three – dimensional (3D) finite element
(FE) integrated jack-up structure – skirted spudcan – soil – interaction
modellings documenting that during the rig installation / preloading and
storm loading the structural forces fall within the accepted limits. The rig was
suceessfully installed and upgraded verifying the engineering predictions.
INTRODUCTION
In the design and installation of different offshore structures an important aspect is the
investigation of the seabed conditions considering features such as slopes, depressions,
boulders, seabed inclination etc. Particularly for a jack-up drilling rig, which is supported
by three independents legs at an approximate distance of (50 – 60) m from each other, this
is a very important issue.
In addition to seabed features the variation of the soil conditions in depth and
horizontal directions, at the three footing locations plays also a decisive role in the structure
and foundation solution.
A geotechnical engineering assessment for the world's largest jack-up rig is given in
L Kellezi, G Kudsk, H Hofstede, Jack-up Rig Foundation Design Applying 3D FE Structure-Soil-Interaction Modeling
Proceedings of the BGA International Conference on Foundations, Dundee, Scotland,24 – 27 June 2008. IHS BRE
Press, 2008.
2. Kellezi, Kudsk, Hofstede
this paper. The rig was temporarily installed next to a quay of a Norwegian yard in order to
be upgraded for further production work in the North Sea.
The preliminary site survey indicated that the seabed in the considered area of
location was rock outcrop, undulating across the site creating slopes and depressions.
As the current rig’s footings are skirted spudcans with areas exceeding the plan
dimensions of the seabed features and the skirts cannot penetrate through the rock, seabed
modification was necessary. The idea of creating flat areas at the footing’s locations,
through construction of shallow gravel / sand banks to a height slightly larger than the skirt
heights, was initially proposed.
After the preliminary site survey a detailed geotechnical investigation was carried out
to verify the soil conditions. From the investigation a sediment layer of varying thickness
overlying the undulating bedrock was identified.
Preliminary conventional and numerical skirted spudcan penetration analyses, with
originally low and lately rather increased elevations of the sand banks, indicated
non-uniform penetration, sliding and rotation of the free skirted spudcans under preloading
conditions. For a more realistic evaluation, jack-up structure - foundation interaction effects
were accounted for in the analyses.
The full 3D FE jack-up structure – skirted spudcans – sand bank – soil - interaction
models were applied for varying heights of the sand banks, investigating the non-uniform
footings penetrations, rotations and sliding and how they effect the structure. After an
extensive amount of analyses, the final heights of the sand banks are proposed.
JACK-UP STRUCTURE – SKIRTED SPUDCAN - SOIL SYSTEM
The current jack-up drilling rig, the world’s largest, is type independent leg cantilever and
is shown in Fig. 1 in comparison to other world known structures. It operates in water
depths up to 150 m and it has leg lengths of about 205 m.
300 m
200 m
100 m
Eiffel Tower Tower Bridge Maersk London Eye Great Belt East
Inspirer Bridge Pylon
Fig. 1. The jack-up rig in comparison to other structures
Structure elements and stiffness
In the 3D FE jack-up - foundation - interaction model only the main structure elements such
3. Jack-up Rig Foundation Design Applying 3D FE Structure-Soil-Interaction Modeling
as the three legs and the hull were included. The legs were simplified to 3D beam elements,
and the hull to plate or floor elements with the equivalent thickness. The rig designer
provided the geometry data for the legs and the hull.
Skirted spudcan geometry
The considered jack-up footings have a diameter D = 22 m and are fitted with outer and
internal skirts, which divide the spudcan into 6 compartments. Fig. 2 shows photo views of
the spudcan inside and a 3D model.
Fig. 2. Jack-up skirted spudcan
The vertical geometry of the spudcan structure is mainly given by: Distance from
spudcan base to tip of outer skirts 2.3 m; Distance from spudcan base to tip of internal skirts
1.1 m; The spudcan itself is almost a flat rigid plate. The transverse stiffnesses of the skirts
are derived from the structural FE model of the spudcan. These thicknesses are applied in
the 3D FE analyses employing wall structural elements, respectively.
Interpretation of the soil conditions
Except the preliminary site survey, to identify the seabed and the soil conditions at the
considered spudcan locations a new site survey, seismic, (sparker and pinger) and
bathymetry was carried out. Sediments of varying thickness overlaying the bedrock were
interpreted. The largest sediment thicknesses were seen at the largest water depth. Gravity
vibrocore samples taken from seabed could not reach the bedrock and showed mostly
sediments of clayey, gravely sand. At the shallow water depths the bedrock outcrops the
seabed.
After the interpretation of the seismic survey geotechnical investigation including 5
piezo-cone penetration tests (PCPTs) and one vibrocore for each spudcan location were
carried out. Discrepancies were though recognized at some PCPT locations. Considering
the limitations of the sparker survey, a pinger survey was carried out. With a less
penetrating, but a smaller opening angle seismic source, the pinger survey was applied to
better identify the slope of the bedrock and supplement the previous investigations in the
area. Based on the pinger data combined with the existing and new soil information, a
re-interpreted model of the sediment and bedrock surface was produced.
Several originally proposed locations were studied finally focusing on one of them.
At each leg position four vertical cross sections such as north - south, west - east, northwest
- southeast, northeast - southwest were interpreted showing the seabed depth and the depth
of the top bedrock from the centre of the spudcans out to a distance of 50 m.
4. Kellezi, Kudsk, Hofstede
To estimate the variation in thickness of the soil layers between the bedrock and the
seabed and the soil parameters applicable to the design of the foundations at the final
location a new geotechnical investigation consisting of 5 boreholes, about 70 PCPTs and
laboratory tests, classification and simple and advanced strength tests were carried out.
From the engineering interpretation of the gathered soil data it was assessed that the
soil conditions consist of overall quaternary marine sediments, mainly deposits consisting
of a seabed layer of sand overlying clayey, sandy silt with variable thickness (0 - 9) m
overlying crystalline bedrock.
Water depth variation
The water depth at the centre of the three chosen spudcan locations are as seen from Fig. 3,
approximately –23 m at spudcan S1, -19 m at S2 and –26.5 m at S3. So the location of S2 is
shallowest, becoming deeper at S1 and even deeper at S3.
Fig. 3. Bathymetry at the considered rig location
Design soil profiles and parameters
On the basis of the seismic surveys, PCPTs / boreholes and laboratory test results
(classification and triaxial, unconsolidated undrained (UU) and consolidated isotropic
drained (CID)) the soil profiles and soil parameters applicable to the engineering
assessment of the jack-up at the considered location are derived.
A good correlation with the PCPT data was investigated for the depths where soil
samples were taken and laboratory tests performed. However, at the depths where lower
cone strength as shown in Fig. 4 and Fig. 5 were recorded no soil sample could be extracted
and no correlation was available. Under these circumstances the cone factor N = qnet / cu =
(15 – 20) was used. When applying such a correlation on the PCPT data undrained shear
strength for the silt cu = (15 – 25) kPa were assessed.
Based on the test results and the engineering judgement initially cu = 25 kPa for the
silt and a friction angle = 35 for the seabed sand were applied.
5. Jack-up Rig Foundation Design Applying 3D FE Structure-Soil-Interaction Modeling
Fig. 4. PCPT profile at S1 location Fig. 5. PCPT profile at S3 location
The soil parameters for the bedrock are evaluated based on the engineering
experience. An undrained shear strength cu = (1000 – 1500) kPa was assigned.
‘As it was’ soil profile at the three spudcan location can be given by Table 1. There
are three soil layers throughout the site. However, the thickness and the elevations of the
layers strongly vary not only between the spudcan locations but also within the spudcan
areas.
Table 1. ‘As it was´ soil profile at the considered jack- up footings locations
Angle of
Depth of Undrained Deformation
Unit weight internal friction
Soil description layer shear strength Modulus
' (kN/m3) and dilation
h (m) cu (kN/m2) E (kN / m2)
() ()
SAND, dense Variable 10.0 35 5 - 35000
SILT / CLAY, very
Variable 9.0 - - 25 / 15 100 * cu
soft to soft
BEDROCK Variable 12.0 - - 1500 / 1000 200 * cu
The material of the sand bank constructed over the seabed at the spudcan locations is
modelled applying a unit weight ' = 11 kN/m3, a friction angle = (40 – 45) and a dilation
angle = (10 – 15) . The deformation parameters E = 100000 kPa was assigned.
The variation of the soil conditions with depth through the considered jack-up area is
shown in the next sections showing different cross sections where the final sand banks
6. Kellezi, Kudsk, Hofstede
proposed for stabilizing the foundations are included.
CONVENTIONAL AND NUMERICAL ANALYSES
Skirted spudcan capacities / stabilities under preloading conditions are investigated
applying different methods of foundation analyses consisting of conventional and 2D / 3D
FE modelling. The common conventional skirted spudcan penetration analyses are not
directly applicable in this case as the thickness of the soil layers vary within the spudcan
area and a uniform soil profile can not be assumed.
The results from the 2D FE analyses of the free-skirted spudcans – soil interaction
considering shallow sand banks, were found conservative as well. Therefore, 3D FE
modelling was performed assigning boreholes at the location where soil profile changes.
The preliminary analyses applying cu = 25 kPa for the silt layer showed large
rotations and horizontal movement for the free skirted spudcans S1 and S3 where the
thickness of the silt layer is considerable and variable. Spudcan S2 is found more stable as
the silt layer is almost negligible and the height of the sand bank is conditioned from the
skirt depth.
An attempt to include some structural stabilizing loads considering leg-spudcan
rigidity while preloading the spudcans was made. The iterative procedure was found
cumbersome and therefore cancelled.
The issue of structure – foundation - soil interaction was raised at this time. The idea
of a full 3D model consisting of jack-up structure – skirted spudcans founded in the sand
banks constructed over the underlying soil was explored. The height of the gravel banks
were then to be determined based on the limited structural forces evaluated from the rig
designer. The structure – foundation system was investigated under preloading and storm
loading conditions.
Conventional skirted spudcan differential penetration
Before building the full 3D structure foundation model, which is complicated and requires
time for calculation, an investigation on the effect of the sand bank heights on the skirted
spudca bearing capacity and differential penetration at the locations S1 and S2 is carried out.
The minimum height at S2 is already defined.
Two extreme soil profiles within the spudcan area are chosen, which are expected to
give maximum and minimum penetrations. The differences in penetrations are interpreted
as differential penetrations of the free-skirted spudcan. The method is not considered
accurate for the final design but serves as preliminary evaluation.
To conventionally define footing penetration depth versus load, calculation of the
static bearing capacity of the spudcan and the skirt elements at various depths, is carried out.
When the spudcan reaches full base contact the assumption for an embedded footing is
applied. This analytical calculation method is previously verified from the FE modelling of
the skirted spudcan resting on different soil conditions.
The spudcan bearing capacity is calculated conventionally based on SNAME 1 and
Hansen’s theory 2 and a program developed from the experience with spudcan penetration
predictions. The spudcan is simplified to a circular footing having a flat bottom. However,
the effect of the actual spudcan shape is taken into account.
When frictional soil overlies firm to stiff clay, punching failure is investigated using
a load spread factor 1:3, assumption applied in connection with the skirt effect. This is
7. Jack-up Rig Foundation Design Applying 3D FE Structure-Soil-Interaction Modeling
verified from previous FE analysis of the spudcan penetration in sand-clay soil profiles. In
addition, squeezing of the clay soil below the spudcan skirt is taken into account as well.
The penetration resistance of the skirt elements is calculated as the sum of the end
resistance and skin resistance. The calculated bearing areas and the skin friction areas are
applied, respectively. Danish Code of Practice for the pile theory is used.
To see the effect of the sand bank height in the differential penetration at spudcan S1
the elevation of the bank is moved up from -21 m to -19 m to -14 m. No punch through risk
was expected for any of the scenarios. The results for sand bank at elevation –21 m and –19
m are given for illustration in Fig. 6. The maximum preload 145 MN / leg is calculated.
The conventional analyses for the soil profiles giving maximum penetrations are also
compared with some FE axisymmetric analyses of the spudcan penetration as shown in Fig.
6. Such analyses are previously carried out by Kellezi & Stromann 3, Kellezi et al. 4,,5 etc.
Fig. 6, Conventional skirted spudcan differential penetration analysis assuming extreme soil conditions at
S1: a) Sand bank at –21 m; b) Sand bank at –19 m;
For spudcan S2 the height of the sand bank is equal to the length of the skirt /
chord, plus some tolerance. The top of the bank was assumed at -13.5 m and small
differential penetrations were predicted.
For spudcan S3 two extreme soil profiles are chosen as well expected to give
maximum and minimum penetrations. The elevation of the gravel bank is moved up from
-25 m to -23 m to -21 m to -18 m to -16 m. No punch through risk is expected.
To make the location applicable for the rig installation, high sand banks were
necessary based on the conventional and FE axisymmetric results applying the soil
mechanic principle of load spreading. Higher banks increase the bearing capacity of the
silt layer as a result of increasing ‘fictive’ bearing area.
8. Kellezi, Kudsk, Hofstede
3D FE jack-up – skirted spudcan – sand banks - interaction modelling
The full 3D model is shown in Fig. 7 and 8. Different models with slightly different heights
of the gravel banks were investigated.
Boreholes
Fig. 7. 3D FE structure-foundation model, 2D build-up, horizontal plane at Hull Level +4.0 m
S3 Elevation
–15.8 m S1 Elevation
–14.5 m
S2 Elevation
–13.5 m
Fig. 8. 3D FE structure-foundation model, final sand banks
9. Jack-up Rig Foundation Design Applying 3D FE Structure-Soil-Interaction Modeling
The scenario with sand bank elevations at –14.5 m, (height about 8.5 m), -13.5 m,
(height about 5.5 m), -15.8 m, (height about 10.7 m) for S1, S2 and S3 locations,
respectively was finally proposed.
The skirted spudcans are simplified by octahedrons. The spudcan is flat and in full
contact with the sand bank from the start of the preloading. The 3 chords are not included.
The tip of the outer skirts is from the start of the analyses at elevation calculated from bank
elevation minus 2.3 m (the skirt length).
The jack-up structure is modelled as shown in Fig. 8. The leg elements can change
length due to applied axial force. The leg beams and the spudcan plates at the connection
points can simulate the 6 degrees of freedoms.
The soil conditions, (soil profiles derived from the seismic, PCPT / borehole data at
different cross sections), are modelled by implementing boreholes, as seen from the
horizontal planes in Fig. 7. Some of the cross sections showing the soil profiles / sections
with final gravel banks are given in Fig. 9.
S1 North West-South East
Sand bank
Seabed sand
S2 North-South
Silt
S3 North West-South East
Bedrock
Fig. 9. Cross section profile through the model and the skirted spudcan locations
10. Kellezi, Kudsk, Hofstede
The calculation procedure consists of 3 load stages, which are: Preloading to max
vertical load V =145 MN / leg; Unload to vertical V = 112 MN / leg, V = 100 MN / leg, V
= 115 MN / leg for S1, S2, S3, respectively; Storm loading, horizontal H = 6.4 MN, moment
M = 345.6 MNm at the most critical plane for wind speed 33 m/s. The storm load comes
from any direction so different analyses were needed to define the critical one.
The loads for preloading are applied as vertical forces at each leg. The horizontal
force is applied at the hull plate pointing towards the critical leg. The moment is
implemented as a set of two vertical loads, applied downward at the critical leg-hull
connection and upwards at a point in the hull between the other two legs as shown in Fig.
8. An initial phase is calculated consisting of the construction of the sand banks.
The limited combined loads at the structure, one single leg, are calculated from
the rig designer as: Horizontal shear force Q = 18 MN / leg; Bending moment at hull M
= 325 MNm / leg;
The soil strength for the silt layer cu = 25 kPa, initially applied based on the
engineering judgement was not considered a lower bound assessment based on the PCPT
data and usual North Sea (qnet - cu) correlation. After reviewing the available soil data, to
increase to some level safety concerning the soil parameters following DNV 6 it was
decided to reduce the shear strength for the silt layer from cu = 25 kPa to cu = 15 kPa. This
strength is considered a lower bound design value, when taking into account the
consolidation during construction of the banks.
The FE analyses are carried out with Plaxis programs 7, 8 . The sand bank material
was specified to correspond to the soil strength applied in the analyses. The total volume
of the sand material was about 60000 m3.
Results from the 3D FE structure – foundation model
The results for the initial phase, including the construction of the sand banks indicated
vertical non-uniform settlements of about 30 cm, taken into account in the calculation of the
total sand volume.
The structural reaction forces for different models and preloading phase are given in
Table 2.
Table 2. Results from 3D FE model, different gravel bank elevation scenarios
3D models Silt Undrained Shear Structure Reaction, Structure Reaction,
Sand Bank Elevation (m) Strength cu (kPa) Bending Moment Shear Force
S1 S2 S3 M (MNm) Q (MN)
–20.0, -13.5, -24.0 cu = 25 Over Limit Over Limit
–16.8, -13.5, -19.1 cu = 25 295.0 17.7
–15.8, -13.5, -18.1 cu = 25 224.7 14.4
cu = 20 Over Limit Over Limit
–15.8, -13.5, -18.1
cu = 15 Over Limit Over Limit
–14.5, -13.5, -16.8
cu = 15 229.8 16.1
–14.0, -13.5, -16.3
-14.5, -13.5, -15.8 cu = 15 211.0 15.1
The structure and spudcan vertical and maximum horizontal displacements are given
in Fig. 10. The maximum calculated reaction forces are M = 211.04 MNm, shear force Qmax
11. Jack-up Rig Foundation Design Applying 3D FE Structure-Soil-Interaction Modeling
= 15.13 MN, differential penetration at S1 about 20 cm, sliding of S1 about 12 cm. The
calculations for the unloading and storm loading analyses show only slight changes in the
deformations and structure reaction forces.
Fig. 10. Preloading phase, structure displacements (only plate elements shown):
a) Vertical displacements b) Horizontal displacement
12. Kellezi, Kudsk, Hofstede
The mechanism of non-uniform penetration or rotation for S1 an S3 can be explained
with the varying thickness of the total sand material and the underlying silt layer, within the
spudcan area. The outward rotation of S1 is for example expected due to thinner friction
material in the north-northwest.
The final bank elevations seem to be the optimum ones. Reducing the bank heights at
one location, for example at S3 if elevation is reduced at –16.8 m, this have a strong effect
in the structure reaction forces as seen from the results in Table 2.
No punch through or rapid penetration was predicted and the spudcans will penetrate
to about full base contact. Some differential spudcan penetrations, rotation and horizontal
movement could though occur during preloading, believed not to be critical for the jack-up
structure. However, from the load displacement curves the inward horizontal movement of
S1 is in the plastic phase and could further develop. Failure figure at for example S1 is given
in Fig. 11. Stability analysis showed safety factor slightly over 1.0.
S1 - Critical Section
Fig.
Fig. 11. Critical failure figure at S1, total displacement increments
CONCLUSIONS
3D FE structure - foundation interaction analyses are carried out for the installation of the
world’s largest jack-up rig, offshore, Norway, where seabed features like slopes and
depressions and non-uniform soil conditions were the concern.
Banks of sands were designed at the skirted spudcan locations with different heights,
ensuring that the structure reaction forces developed during preloading, causing footings
rotation / sliding, did not exceed the calculated limits.
The jack-up rig was successfully installed at the location and spudcan penetrations /
displacements similar to the predicted values were recorded.
13. Jack-up Rig Foundation Design Applying 3D FE Structure-Soil-Interaction Modeling
ACKNOWLEDGEMENT
The authors are grateful to Maersk Contractors, Copenhagen for supporting this project.
REFERENCES
1. SNAME, T&R Bulletin 5-5A January 2002. Site Specific Assessment of Mobile
Jack-Up Units. The Society of Naval Architects and Marine Engineers.
2. Hansen J B. A revised and extended formula for bearing capacity,. Bulletin No. 28,
1970, The Danish Geotechnical Institute, pp. 5-11.
3. Kellezi, L., and Stromann H., 2003, FEM analysis of jack-up spudcan penetration for
multi-layered critical soil conditions. Proc. of BGA Intern. Conf. on Foundations,
ICOF2003, Dundee, Scotland, pp. 410-420.
4. Kellezi L, Hofstede H and Hansen P B. Jack-up footing penetration and fixity analyses,
Proc. ISFOG 2005, Sept., Perth, Australia, pp. 559 – 565.
5. Kellezi L, H Denver, G Kudsk, H Stadsgaard. FE skirted footings analyses for
combined loads and layered soil profile, ECSMGE 2007, Proc. pp. 341-346.
6. DNV (Det Norske Veritas) Foundations classification notes No. 30.4. February 1992
7. Plaxis 2002, Version 8.4. User Manual 2D, Delft University of Techn. and Plaxis b.v
8 Plaxis 3D 2006, Foundation Module Version 1.6, Delft Univ. of Techn and Plaxis b.v.