scholarly journals Load Transfer of Offshore Open-Ended Pipe Piles Considering the Effect of Soil Plugging

2019 ◽  
Vol 7 (9) ◽  
pp. 313 ◽  
Author(s):  
Liu ◽  
Guo ◽  
Han
Keyword(s):  
Load Transfer ◽  
Earth Pressure ◽  
Offshore Structures ◽  
Rigid Plastic ◽  
Soil Plug ◽  
Centrifuge Testing ◽  
Trilinear Model ◽  
Method Model ◽  
Transfer Properties ◽  
Shaft Friction

Open-ended pipe piles have been increasingly used as the foundations for offshore structures. Considering the soil plugging effect, a novel analytical model is proposed in this paper to study the load transfer mechanism of open-ended pipe piles. A trilinear model for the external shaft friction was introduced, while a rigid plastic model was adopted to describe the load transfer at the pile-plug interface. Furthermore, an equilibrium equation of the soil plug was proposed, based on the hypothesis of a trilinear distribution of lateral earth pressure. The pile end resistance was analyzed by dividing it into two parts, i.e., the soil plug and pile annulus, the behaviors of which were described by the double broken line model. A calculation example was carried out to analyze the load transfer properties of the open-ended pipe piles. As a validation, similar load transfer processes of the open-ended pile were also captured in a newly built discrete element method model, mimicking the 100g centrifuge testing conditions.

Earth pressures exerted on an induced trench cast-in-place double-cell rectangular box culvert

2012 ◽  
Vol 49 (11) ◽  
pp. 1267-1284 ◽  
Author(s):  
Olajide Samuel Oshati ◽  
Arun J. Valsangkar ◽  
Allison B. Schriver
Keyword(s):  
Earth Pressure ◽  
Test Results ◽  
Overburden Pressure ◽  
Centrifuge Testing ◽  
Geotechnical Centrifuge ◽  
Drag Forces ◽  
Field Instrumentation ◽  
Earth Pressures ◽  
Box Culvert ◽  
Base Contact

Earth pressure data from the field instrumentation of a cast-in-place reinforced rectangular box culvert are presented in this paper. The instrumented culvert is a 2.60 m by 3.60 m double-cell reinforced cast-in-place rectangular box buried under 25.10 m of fill constructed using the induced trench installation (ITI) method. The average earth pressure measured across the roof was 0.42 times the overburden pressure, and an average of 0.52 times the overburden pressure was measured at mid-height of the culvert on the sidewalls. Base contact pressure under the rectangular box culvert was also measured, providing field-based data demonstrating increased base pressure resulting from downward drag forces developed along the sidewalls of the box culvert. An average increase of 25% from the measured vertical earth pressures on the roof plus the culvert dead load (DL) pressure was calculated at the culvert base. A model culvert was also tested in a geotechnical centrifuge to obtain data on earth pressures at the top, sides, and base of the culvert. The data from the centrifuge testing were compared with the prototype structure, and the centrifuge test results agreed closely with the measured field prototype pressures, in spite of the fact that full similitude was not attempted in centrifuge testing.

Structural Integrity Control of Ageing Offshore Structures: Repairing and Strengthening With Grouted Connections

2013 ◽  
Author(s):  
S. M. S. M. K. Samarakoon ◽  
R. M. Chandima Ratnayake ◽  
S. A. S. C. Siriwardane
Keyword(s):  
Structural Integrity ◽  
Oil And Gas ◽  
Load Transfer ◽  
Fatigue Loading ◽  
Offshore Structures ◽  
Future Research ◽  
Offshore Platforms ◽  
Historical Evidence ◽  
Design Service Life ◽  
Pros And Cons

Structural integrity control (SIC) is an increasingly important element of offshore structures. Not only is it used in newly built and existing offshore structures (e.g. oil and gas (O&G) production & process facilities (P&PFs), wind turbine installations, etc.), but SIC is also essential for ageing offshore platforms which are subjected to an extension of their design service life. In these cases, SIC programs must be performed to assess the platforms. If any significant changes in structural integrity (SI) are discovered, then it is essential to implement an appropriate strengthening, modification and/or repair (SMR) plan. Currently, welded and grouted repairs are mostly used for SMR. Although a welded repair may typically restore a structure to its initial condition, if the damage is due to fatigue loading and welded repairs have been carried out, then historical evidence reveals that there is a high potential for the damage to reappear over time. On the other hand, mechanical connections are significantly heavier than grouted connections. Consequently, grouted repairs are widely used to provide additional strength, for instance, to handle situations such as preventing propagation of a dent or buckle, sleeved repairs, leg strengthening, clamped repair for load transfer, leak sealing and plugging, etc. This manuscript examines current developments in grouted connections and their comparative pros and cons in relation to welded or mechanical connections. It also provides recommendations for future research requirements to further develop SMR with grouted connections.

Field performance, centrifuge testing, and numerical modelling of an induced trench installation

2008 ◽  
Vol 45 (1) ◽  
pp. 85-101 ◽  
Author(s):  
Rodney P. McAffee ◽  
Arun J. Valsangkar
Keyword(s):  
Numerical Modelling ◽  
Pressure Distribution ◽  
Earth Pressure ◽  
Field Performance ◽  
Overburden Pressure ◽  
Centrifuge Testing ◽  
Geotechnical Centrifuge ◽  
Earth Pressures ◽  
Prototype Structure ◽  
Box Culvert

The field performance of an induced trench installation is compared to the results of centrifuge testing and numerical modelling. The measured vertical pressure at the crown of the pipe in the field ranged from 0.24 to 0.36 times the overburden pressure. The horizontal earth pressures measured in the field at the springline level determined a coefficient of lateral earth pressure between 0.39 and 0.49. The culvert was monitored over a period of 2 years following completion of embankment construction indicating no measurable changes in earth pressures and deformations. A model box culvert simulating the prototype height of soil cover, the pipe width, and the thickness of the compressible layer was tested using a geotechnical centrifuge. The prototype structure was also evaluated using numerical modelling to predict full earth pressure distribution and deformations. A comparison of field data, centrifuge testing, and numerical modelling shows that the Marston–Spangler theory used in designing induced trench culverts is conservative. The theory however, does not address or predict the nonuniform pressures on the top, sides, or bottom of the pipe, and therefore numerical analysis should be used to estimate the complete pressure distribution.

Pile Bearing Properties Analysis Based on Energy Method

2013 ◽  
Vol 639-640 ◽  
pp. 704-707
Author(s):  
Si Si Liu ◽  
Zhong Qiu Xie
Keyword(s):  
Load Transfer ◽  
Energy Balance Equation ◽  
Curve Analysis ◽  
Engineering Practice ◽  
Analysis Method ◽  
Bilinear Model ◽  
Side Load ◽  
Trilinear Model ◽  
Calculation Results

Energy transfer of pile body in foundation is considered by the energy balance equation of pile unit. Bilinear model is used to calculate the pile side load transfer, and trilinear model to calculate the toe resistance load transfer. According to the deformation coordinating relations, pile load-settlement curve analysis method is obtained. Comparing the in-situ and calculation data, the results show that they are basically consistent. The conclusions are pile bearing properties can be analyzed reasonably by this method, and the calculation results can provide a reference to engineering practice.

Full-scale Test on Emergency Repair Pavement under Airplane Loading

2022 ◽  
pp. 1-27
Author(s):  
Jun Zhang ◽  
Wei Xu ◽  
Peiwei Gao ◽  
Xingzhong Weng ◽  
Lihai Su
Keyword(s):  
Optimization Design ◽  
Load Transfer ◽  
Gaussian Function ◽  
Structural Response ◽  
Earth Pressure ◽  
Concrete Pavement ◽  
Emergency Repair ◽  
The Earth ◽  
Reinforced Plastic ◽  
Quartic Polynomial

In order to reveal structural response law of emergency repair pavement under the airplane loading and verify the backfill material and structural applicability, two craters (Crater 1 composed of 2.4 m thick flying objects (FO) + 0.4 m thick graded crushed rocks (GCR) + 0.2 m thick roller compacted concrete + fibre reinforced plastic (FRP) course, and Crater 2 composed of 2.4 m thick FO + 0.6 m thick GCR + FRP course) were backfilled. Static and dynamic loads were applied using two airplanes. Results show that, laying FRP pavement layers reduced the maximum deflection of Crater 2 by 21%. Crater 1 and concrete pavement were both slightly rigid structures with a strong load transfer ability. The dynamic deflection basin curves of Crater 2 could be fit using a Gaussian function; while the curves of Crater 1 and concrete pavement could be fit using a quartic polynomial. Under static loading, the earth pressures of Crater 2 at −0.6 m, −0.4 m, and −0.2 m sites were 4.3, 9, and 9.6 times of those of Crater 1, respectively. At the −0.2 m site, the earth pressure of Crater 1 was 0.11 MPa, while that of Crater 2 reached 1.06 MPa. The research results can guide the rapid quality inspection and optimization design of emergency repair pavement structure and material.

Weld Root Fatigue Assessment of Fillet-Welded Structures Based on Structural Stresses

2006 ◽  
Author(s):  
Wolfgang Fricke
Keyword(s):  
Load Transfer ◽  
Fatigue Cracking ◽  
Offshore Structures ◽  
Additional Stress ◽  
Stress Concentrations ◽  
Plate Structures ◽  
Fatigue Assessment ◽  
Notch Stress ◽  
Weld Root ◽  
Initial Cracks

The problem of fatigue cracking is particularly significant for large welded plate structures being typical for ships and floating offshore structures. Here, fillet welding is applied to a large extent to join structural components. This leads to non-fused root faces, which can behave like initial cracks. In several cases the situation is even worse, when welding can be performed from one side only, resulting in a highly-stressed weld root on the other side. Although refined approaches exist for a fatigue assessment of such weld roots, for instance the crack propagation and the notch stress approaches, more practical approaches requiring less effort are demanded to handle typical problems occurring in practice. These problems are associated with locally increased load transfer, e.g. at crossing support structures and at fillet welded ends of attachments with additional stress concentrations. Also, pronounced bending can occur in fillet welds due to lateral loading of the attachment and/or the eccentricity of one-sided welds. In the paper, practical approaches for such problems are presented which have been developed in the recent past in different research projects and which are based on a structural stress or a local nominal stress in the weld. Their application is demonstrated by several examples taken from ship and offshore structures using relatively coarse finite element meshes for the stress analyses.

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