Centrifuge Model Tests on Effects of Spudcan Penetration on Adjacent Loaded Piles

2020 ◽  
Author(s):  
Jianhua Wang ◽  
Yifei Fan
Keyword(s):  
Model Test ◽  
Frictional Resistance ◽  
Fine Sand ◽  
Model Tests ◽  
Offshore Platforms ◽  
Pile Head ◽  
Centrifuge Model ◽  
Pile Shaft ◽  
Axial Forces ◽  
Centrifuge Model Tests

Abstract It is very important for designers of offshore platforms to understand affecting mechanism of mobile jack-up spudcan penetration and extraction on adjacent loaded piles. Existing centrifuge model tests are on effects of spudcan penetration on adjacent unloaded piles. In engineering, offshore platform piles are subjected to lateral and vertical pile head loads before spudcan penetration. In order to understand affecting mechanism of spudcan penetration on adjacent loaded piles, centrifuge model tests were conducted under 50g condition. Model test strata are the saturated soft clay and the fine sand and the model pile head constraint is free. Spudcan penetration resistances, lateral earth pressures along pile shaft, lateral pile deflection, vertical pile displacement, bending moments and axial forces along pile shaft are measured during spudcan penetration and after extraction. Effects of spudcan penetration on the pile-soil interaction p-y relationship and the bearing capacity of piles are analyzed based on model test results. Results show that the lateral soil resistance affected by spudcan penetration decreases due to soil movement. The lateral deflection of loaded pile obviously increases, the side frictional resistance decreases and the end resistance increases during spudcan penetration. The spudcan penetration-induced incremental pile response does not disappear after spudcan extraction. These results are helpful for understanding the effect mechanism of spudcan penetration and extraction on adjacent loaded piles.

Numerical Simulation and Analysis of Centrifuge Model Tests with Nonhomogeneous Materials in Geotechnical Engineering

2013 ◽  
Vol 353-356 ◽  
pp. 495-501
Author(s):  
Lie Xian Tang ◽  
Lian Jun Guo ◽  
Da Ning Zhang ◽  
Jian Ming Zheng
Keyword(s):  
Numerical Simulation ◽  
Model Test ◽  
Geotechnical Engineering ◽  
Model Tests ◽  
Centrifuge Model Test ◽  
Test Model ◽  
Geotechnical Centrifuge ◽  
Centrifuge Model ◽  
Centrifuge Tests ◽  
Centrifuge Model Tests

The primary methods are antetype observation and model tests which to check the actual engineering status in geotechnical engineering field. The antetype observation is the best direct and convictive method, but approach miscellaneous and spend hugely. The general model tests can not fulfil the same stress between model and antetype. Geotechnical centrifuge model test can not only minish the measure of model and fulfil the comparability condition, but also can found all kinds of non-symmetrical models and simulation all kinds of complicated engineering. So the geotechnical centrifuge model test is applied widely in the geotechnical engineering. This paper used the RFPA-Centrifuge and recured to the principle of geotechnical centrifuge model test, evaluated the safety of model only by increase the physical strength. Though the numerical calculating in nonhomogeneous models with different scales showed that stress, displacement and failure mode were accord with conform ratio of centrifuge model tests. Showed the advantage that the results of RFPA can be validated each other with results of physical tests. For some specifical complicated items in geotechnical engineering, make a good test model is not only very hard and have to spend much time, but also need expensive test equipment and much money for test materials. It is very good if we can use a method to conquer these shortages. So it is advisable that using the mechod which geotechnical centrifuge tests combine RFPA-Centrifuge numerical simulation analysis method.

scholarly journals Centrifuge Model Test on the Settlement of Valley-Type Loess Filled after Construction and Subjected to Rainfall Infiltration

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Jiwen Zhang ◽  
Jie Cao ◽  
Bo Li ◽  
Kunye Zhou ◽  
Xilin Lü
Keyword(s):  
Model Test ◽  
Large Scale ◽  
Rapid Development ◽  
Model Tests ◽  
Rainfall Infiltration ◽  
Western China ◽  
Centrifuge Model Test ◽  
Filling Material ◽  
Centrifuge Model ◽  
Centrifuge Model Tests

With the rapid development of infrastructure construction in western China where hilly and gully areas are distributed, there are lots of large-scale filling engineering in recent years. In the area where collapsible loess is widely distributed, it is inevitable to use loess as filling material. Considering the collapsibility of loess, centrifuge model tests were conducted to study the settlement of loess fill in a valley after construction and subjected to rainfall infiltration. To provide a comparison, a centrifuge model test of loess filling body on a flat ground was conducted, and results showed that the settlement of loess fill during the construction stage is larger than the one at the postconstruction stage, and the unloading rebound deformation caused by decreasing gravity is about 15% of the deformation induced by increasing gravity. Two centrifuge model tests were conducted to study the settlement of the loess filling body in a valley; the varying characteristics of settlement and earth pressure with time at the postconstruction stage and subjected to rainfall infiltration were investigated. Differential settlement in the ground surface was observed at the postconstruction stage, and it was found to become very small under the rainfall infiltration condition. Comparison of the test results showed that insufficient compaction in the lower part of the filling body significantly increases the ground settlement at the postconstruction stage.

Evaluation of the seismic response of stone pagodas using centrifuge model tests

2014 ◽  
Vol 12 (6) ◽  
pp. 2583-2606 ◽  
Author(s):  
Heon-Joon Park ◽  
Dong-Soo Kim ◽  
Yun Wook Choo
Keyword(s):  
Seismic Response ◽  
Model Tests ◽  
Centrifuge Model ◽  
Centrifuge Model Tests

scholarly journals Evaluation of seismic behavior of box culvert buried in the ground through centrifuge model tests and numerical analysis

2019 ◽  
Vol 4 (2) ◽  
pp. 147-167 ◽  
Author(s):  
Hitoshi Yatsumoto ◽  
Yasuo Mitsuyoshi ◽  
Yasuo Sawamura ◽  
Makoto Kimura
Keyword(s):  
Numerical Analysis ◽  
Seismic Behavior ◽  
Model Tests ◽  
Centrifuge Model ◽  
Box Culvert ◽  
Centrifuge Model Tests

scholarly journals Modelling the embedment process during offshore pipe-laying on fine-grained soils

2013 ◽  
Vol 50 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Z.J. Westgate ◽  
D.J. White ◽  
M.F. Randolph
Keyword(s):  
Deep Water ◽  
Small Amplitude ◽  
Model Tests ◽  
Soil Parameters ◽  
Sea State ◽  
Field Surveys ◽  
Centrifuge Model ◽  
Fine Grained ◽  
Displacement Patterns ◽  
Centrifuge Model Tests

Subsea pipelines are becoming an increasingly significant element of offshore hydrocarbon developments as exploration moves into deep-water environments further from shore. During the lay process, pipelines are subject to small amplitude vertical and horizontal oscillations, driven by the sea state and lay vessel motions. Centrifuge model tests have been used to simulate these small-amplitude lay effects, with varying degrees of idealization relative to the real lay process. In the soft soils found in deep water, pipe embedment can exceed a diameter or more, thus significantly affecting the lateral pipe–soil interaction, axial resistance, and thermal insulation. In this paper, results from centrifuge model tests are used to calibrate a model for calculating the dynamic embedment of a subsea pipeline. The model uses elements of plasticity theory to capture the effects of combined vertical and horizontal loading, and incorporates the softening of the surrounding soil as it is remoulded due to the pipeline motions. Influences from the lay rate, lay geometry, and sea state are included in the calculation process. The model is compared with observed as-laid pipeline embedment data from field surveys at three different offshore sites. Using site-specific soil parameters obtained from in situ testing and idealized pipe loads and motions to represent the load and displacement patterns during offshore pipe-laying, respectively, the model is shown to capture well the final as-laid embedment measured in the field surveys.

RESPONSE OF SOFT CLAY STRATA AND CLAY-PILE-RAFT SYSTEMS TO SEISMIC SHAKING

2007 ◽  
Vol 01 (03) ◽  
pp. 233-255 ◽  
Author(s):  
SUBHADEEP BANERJEE ◽  
SIANG HUAT GOH ◽  
FOOK HOU LEE
Keyword(s):  
Soft Clay ◽  
Ground Surface ◽  
Model Tests ◽  
Pile Foundations ◽  
Kaolin Clay ◽  
Natural Period ◽  
Soil System ◽  
Centrifuge Model ◽  
Inertial Loading ◽  
Centrifuge Model Tests

The behavior of pile foundations under earthquake loading is an important factor affecting the performance of structures. Observations from past earthquakes have shown that piles in firm soils generally perform well, while the performance of piles in soft or liquefied ground can raise some questions. Centrifuge model tests were carried out at the National University of Singapore to investigate the response of pile-soil system under three different earthquake excitations. Some initial tests were done on kaolin clay beds to understand the pure clay behavior under repetitive earthquake shaking. Pile foundations comprising of solid steel, hollow steel and hollow steel pile filled with cement in-fill were then embedded in the kaolin clay beds to study the response of clay-pile system. Superstructural inertial loading on the foundation was modeled by fastening steel weight on top of the model raft. The model test results show that strain softening and stiffness degradation feature strongly in the behaviour of the clay. In uniform clay beds without piles, this is manifested as an increase in resonance periods of the surface response with level of shaking and with successive earthquakes. For the pile systems tested, the effect of the surrounding soft clay was primarily to impose an inertial loading onto the piles, thereby increasing the natural period of the piles over and above that of the pile foundation alone. There is also some evidence that the relative motion between piles and soil leads to aggravated softening of the soil around the pile, thereby lengthening its resonance period of the soil further. The centrifuge model tests were back-analyzed using the finite element code ABAQUS. The analysis shows that the simple non-linear hypoelastic soil model gave reasonably good agreement with the experimental observations. The engineering implication arising from this study so far is that, for the case of relatively short piles in soft clays, the ground surface motions may not be representative of the raft motion. Other than the very small earthquakes, the raft motion has a shorter resonance period than the surrounding soil.

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