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1
Dou, Leisi, Haitao Wang, Bin Li, Yulin Yang e Danyang Di. "Impact of Groundwater Fluctuations on the Stability of Super-Large-Diameter Caissons before and after Reinforcement". Applied Sciences 14, n. 12 (7 giugno 2024): 4971. http://dx.doi.org/10.3390/app14124971.
Testo completoAbstract (sommario):
Super-large-diameter caissons, serving as working wells for trenchless pipe jacking technology, are being extensively constructed alongside the increasing adoption of trenchless technology in urban areas. However, being regarded merely as ancillary structures, the structural stability of a caisson during both construction and operation phases are often neglected. This study, centered on the super-large-diameter caissons within the Jinshui River flood control project in Zhengzhou, China, systematically monitored the mechanical behavior of caisson structures and surface settlement during construction and operational phases. Utilizing a validated FE method, the influence of groundwater fluctuations on the structural stability of caissons during operational phases was examined. Furthermore, potential occurrences of loose soil, voids, and caisson tilting were considered. Subsequently, the applicability of permeable polymer, foam polymer, and anchor rod reinforcement techniques were evaluated, followed by an analysis of the structural stability of the caissons post reinforcement during long-term operations. The findings demonstrate the minimal horizontal displacement of and stress variation in caissons under seasonal groundwater fluctuations, without significant structural alterations. Nevertheless, the presence of loose soil, voids, and caisson inclinations may decline the caisson’s support force and bearing capacity. With the increase in non-compactness, void size, and inclination, the structural stability of caissons notably diminishes. Reinforcing loose soil with permeable polymers, filling voids with foam polymers, and utilizing anchor rods are all effective methods for strengthening caisson structures and enhancing their stability.
2
Iskander, Magued, Sherif El-Gharbawy e Roy Olson. "Performance of suction caissons in sand and clay". Canadian Geotechnical Journal 39, n. 3 (1 giugno 2002): 576–84. http://dx.doi.org/10.1139/t02-030.
Testo completoAbstract (sommario):
The use of suction caissons (suction piles) in marine environments has been increasing in the last decade. A suction caisson is a steel pipe with an open bottom and a closed top that is inserted into the ground by pumping water out of it. Pumping creates a differential pressure across the caisson's top that pushes it into place, thus eliminating the need for pile driving. There are a number of uncertainties in the design of suction caissons. First, the state of stress and soil conditions adjacent to a suction caisson differs from those around typical driven piles or drilled shafts. Second, the axial load capacity of suction caissons depends on the rate of loading, hydraulic conductivity, drainage length, as well as the shearing strength properties of the foundation material. Finally, during pullout, volume change characteristics of the surrounding soils may change the theoretical suction pressures. A review of the existing knowledge relating to the design and construction of suction caissons is presented in this paper along with the results of a laboratory study on model caissons in sand and clay. Test results indicate that the use of suction pressure for installation of caissons is a viable alternative to conventional methods. Suction was also shown to resist some axial tensile loads.Key words: suction, pile, bucket, foundation, anchor, capacity.
3
Park, Min Su, Young Taek Kim, Sangki Park e Jiyoung Min. "Interaction Analysis between Waves and Caissons by Damping Zone Effect for Installing New Caisson on Old Caisson Breakwater". Journal of Korean Society of Coastal and Ocean Engineers 34, n. 5 (31 ottobre 2022): 156–68. http://dx.doi.org/10.9765/kscoe.2022.34.5.156.
Testo completoAbstract (sommario):
The design and construction are carried out to improve the structural stability of caisson breakwaters by installing new caissons on the front or rear of old caissons. The wave forces acting on caisson are excessively calculated by the resonance of fluid existing between the old caisson and the new caisson in the numerical analysis using potential flow. In this study, we used the damping zone option in ANSYS AQWA program to analyze the wave forces acting on individual caissons according to the interaction effects between the incident wave and the caisson. By applying the damping zone option to the fluid in which resonance occurs, the wave forces acting on individual caissons were calculated by the change of damping factor. In addition, the wave force characteristics acting on individual caissons were analyzed for the different distances between caissons in the frequency domain analysis.
4
Leung, Chun Fai, e Rui Fu Shen. "Performance of gravity caisson on sand compaction piles". Canadian Geotechnical Journal 45, n. 3 (marzo 2008): 393–407. http://dx.doi.org/10.1139/t07-093.
Testo completoAbstract (sommario):
Gravity caissons were employed as part of the wharf front structures for a container port terminal in Singapore. This paper reports the movements of eight consecutive gravity caissons supported on sand compaction piles (SCPs) with highly variable lengths of penetration. It is established that the caisson movements increase with an increase in the length of the SCP, as longer SCPs are necessary when hard strata are at greater depth. The large caisson movements observed during caisson infilling and backfilling do not pose a concern because the wharf deck beams connecting adjacent caissons can be adjusted. However, the caisson movements under service loads would affect the operation of the overlying quay cranes on top of the caissons. The present field study reveals that preloading the caissons is effective in reducing the caisson movements under service loads because the observed caisson movements are insignificant during subsequent unloading–reloading of the caissons. Back-analysis using the finite element method (FEM) shows that the observed caisson movements at different construction stages can be reasonably replicated. The numerical results are also used to evaluate the caisson tilt angle, which could not be measured in the present field study. The caisson tilt is found to be independent of the length of SCPs underneath a caisson.
5
Park, Min Su, Young Taek Kim, Sangki Park e Jiyoung Min. "Time Response Analysis of Caissons by Installing New Caisson on Existing Caisson Breakwater in Irregular Wave Condition". Journal of Korean Society of Coastal and Ocean Engineers 34, n. 6 (27 dicembre 2022): 233–46. http://dx.doi.org/10.9765/kscoe.2022.34.6.233.
Testo completoAbstract (sommario):
The design and the construction were carried out by installing new caissons on the back or the front of existing caissons to increase the structural stability of caisson breakwaters. In this study, we used the ANSYS AQWA program to analyze the wave forces acting on individual caissons according to the effects of wave-structure interaction when new caissons were additionally installed on existing caisson breakwaters. The wave force characteristics acting on the individual caisson were analyzed according to the distance among caissons in frequency domain analysis. In addition, the dynamic wave force characteristics were closely examined on the basis of the frequency at which the unusual distribution of wave forces occurs in irregular wave conditions using time domain analysis.
6
Park, Min Su. "Interaction Effect between Caissons by Installation of New Caisson on Existing Caisson Breakwater in Second Order Stokes Wave Condition". Journal of Korean Society of Coastal and Ocean Engineers 33, n. 6 (31 dicembre 2021): 345–56. http://dx.doi.org/10.9765/kscoe.2021.33.6.345.
Testo completoAbstract (sommario):
In order to increase the structural stability of existing caisson breakwater, the design and the construction is carried out by installation of new caissons on the back or the front of old caissons. In this study, we use the ANSYS AQWA program to analyze the wave forces acting on individual caisson according to effects of wave structure interaction when new caissons are additionally installed on existing caisson breakwater. Firstly, the wave force characteristics acting on the individual caisson were analyzed for each period (frequency) in the frequency domain. In time domain analysis, the dynamic wave force characteristics were strongly influenced by the distance between caissons on the frequency at which the unusual distribution of wave forces occurs.
7
Chakrabarti, Partha, Subrata K. Chakrabarti, Adinarayana Mukkamala, Nagaraj Anavekar, Shen Qiang e M. Sri Krishna. "Design Analysis of Moored Floating Caisson System". Journal of Offshore Mechanics and Arctic Engineering 127, n. 2 (6 ottobre 2004): 75–82. http://dx.doi.org/10.1115/1.1905640.
Testo completoAbstract (sommario):
Tacoma Narrows Constructors (TNC) are building a new suspension bridge in Tacoma, close to Seattle, Washington State, USA. The new bridge is being built just south of the existing bridge mounted on two caissons. The caissons are constructed on location after the shallow draft caissons are towed to site. During the construction sequence, the mooring system for each caisson consists of two sets of 16 mooring lines. The lower 16 lines are hooked-up after the shallow draft caisson is towed from the harbor and positioned at the site. The fairlead locations for these lines are kept constant throughout the construction process. The fairlead locations for the upper 16 lines (except three lines on the East Caisson) vary based on the caisson draft. The caissons are subject to a high current from the ebb and flood tide flow in the Narrows. The new caissons are in close proximity to the existing piers and the bottom topography at the site is varying. Therefore, considerable turbulence and vortex shedding is expected in the prevailing current, which will cause current-induced dynamic forces on the caissons. This paper describes the design and analysis of this multiline mooring system for Tacoma Narrows Bridge caissons, based on the construction sequence in the floating condition. The analysis involved optimizing the anchor locations and the line pretensions, determining the dynamic motions of the caissons, the maximum line loads, and the corresponding safety factors. The paper also describes the hydrodynamic analysis for added mass, and damping, the methodology used for the nonlinear moored caisson analysis (MOTSIM), and the validation of the design tool with other similar models (e.g., STRUCAD*3D). The results of the analysis and the design of the system are discussed.
8
Xiang, Qiqi, Kai Wei, Fang Qiu, Changrong Yao e Yadong Li. "Experimental Study of Local Scour around Caissons under Unidirectional and Tidal Currents". Water 12, n. 3 (27 febbraio 2020): 640. http://dx.doi.org/10.3390/w12030640.
Testo completoAbstract (sommario):
Local scour around caissons under currents has become one of the main factors affecting the safety of foundation construction and operation in coastal and offshore bridge engineering. Local scour occurs not only in the operation stage, when the caisson has settled into the sediment, but also in the construction stage, when the caisson is suspended in water. In this study, the local scour induced by unidirectional and tidal currents around settled caissons with different cross-sections (circular, square, and diamond) was experimentally investigated. Circular and square caissons were selected to investigate the difference in local scour of suspended caissons under unidirectional and tidal currents. The main findings from the experimental results were: (1) the temporal development of scour under tidal current was slower than that of unidirectional current; (2) the effect of current type can significantly influence the size and location of maximum scour depth around circular and square caissons; (3) the appropriate choice of cross-section could reduce the maximum scour depth around the settled caisson; (4) the maximum scour depth of tidal current was smaller than that of unidirectional current when the caisson was settled into the sediment, while the opposite effect occurred when the caisson was suspended in water.
9
Xu, Chenggen, Haitao Jiang, Mengtao Xu, Decheng Sun e Shengjie Rui. "Calculation Method for Uplift Capacity of Suction Caisson in Sand Considering Different Drainage Conditions". Sustainability 15, n. 1 (27 dicembre 2022): 454. http://dx.doi.org/10.3390/su15010454.
Testo completoAbstract (sommario):
Uplift capacity of suction caissons is one of the main concerns in the design of jackets with multi-caissons supported offshore wind turbine. The uplift movement of suction caissons leads to soil stress variation and increases the difficulty to predict the uplift capacity. In this paper, a calculation method considering soil stress release and differential pressure contribution is proposed to predict the uplift capacity of caisson. Firstly, a series of numerical simulations based on the SANISAND model are conducted to study the uplift responses of suction caisson in sand, and it is verified with centrifuge test results. Considering the soil drainage condition during caisson being pulled out, the fully drained, partially drained and undrained are divided, and an equation is provided to assess differential pressure beneath the caisson lid incorporating the effects of main factors. Based on the above simulation results, a calculation method is proposed to calculate the uplift capacity of caissons. The prediction results are compared with the centrifuge model tests and previous studies, which indicate that the prediction accuracy is much improved. This proposed method contributes to the more accurate assessment of uplift capacity of suction caisson in sand.
10
Zhang, Ji Cheng, e Jun Yang. "Reliability Analysis on Construction Course of Open Caisson Structure". Applied Mechanics and Materials 166-169 (maggio 2012): 1976–80. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.1976.
Testo completoAbstract (sommario):
The numerical model was established using ANSYS software, which took the interaction effect of subsoil and structure into account, the soil was considered as discrete spring elements. The soil’s mechanic parameters were set as random variable, probability analysis was performed on typical construction course of open caisson by Monte-Carlo method, the distribution rule of displacement random variables and their sensitivity to variable factors were studied, and the influence of uncertain factors on open caisson’s sinking attitude was investigated. The analysis model showed good practical value for controlling construction course of open caissons.
11
Zhao, Zhifeng, Mi Zhou, Yuxia Hu e Muhammad Shazzad Hossain. "Behavior of soil heave inside stiffened caissons being installed in clay". Canadian Geotechnical Journal 55, n. 5 (maggio 2018): 698–709. http://dx.doi.org/10.1139/cgj-2016-0667.
Testo completoAbstract (sommario):
The length of suction caisson anchors has been increasing to support increasing dimensions and weight of floating facilities, which necessitates employing horizontal ring stiffeners at intervals along the inner wall of the thin skirt of caissons to ensure structural integrity. The addition of these stiffeners has created significant uncertainties regarding soil flow mechanisms, in particular soil heave inside the caisson, which may reduce the caisson final penetration depth and influence the process of installation due to the need to avoid inside soil suction in the pumping equipment. This paper reports results of large-deformation finite element (LDFE) analyses investigating soil heave inside stiffened caissons during installation in nonhomogeneous clay deposits, with the corresponding evolution of soil flow mechanisms and penetration resistance profiles reported by Zhou et al. in 2016. The LDFE analyses have simulated continuous penetration of stiffened caissons from the seabed surface. A detailed parametric study has been undertaken, exploring the relevant range of soil strength nonhomogeneity and normalized strength, stiffened caisson geometry, soil effective unit weight, and caisson roughness. Of particular interest is the influence of stiffeners on soil heave and potential penetration refusal. The results have been validated against previously published centrifuge test data in terms of soil heave and penetration resistance profile, with good agreement obtained. It is shown that the soil normalized strength at the mudline and its nonhomogeneity, caisson diameter relative to the sum of skirt thickness and stiffener width, and caisson penetration depth have significant influence on the inner soil heave and its profile across the caisson radius. An expression, based on the LDFE results is proposed to predict the maximum inner soil heave during installation of stiffened caissons in the field.
12
Chakrabarti, Subrata K., e Mark McBride. "Model Tests on Current Forces on a Large Bridge Pier Near an Existing Pier". Journal of Offshore Mechanics and Arctic Engineering 127, n. 3 (2 febbraio 2005): 212–19. http://dx.doi.org/10.1115/1.1951772.
Testo completoAbstract (sommario):
A suspension bridge is being built over the Tacoma Narrows, Washington. The bridge will be placed on a structure mounted on two large concrete caissons, which will be exposed to strong currents. The piers are of rectangular section with chamfered edges in the upper portion. The caissons are being built at site while floating and moored in high currents. There are no known analytical methods or experimental data available on such structures at high Reynolds number. In order to determine the forces on the caisson due to current, a series of scaled physical model tests of one of the caissons was carried out. The forces on the caisson were measured in the presence of the existing bridge pier and the bottom contours of the Narrows were accurately modeled. The model scale was chosen as 1:100 and the tests were performed for the caisson at different drafts. This paper describes the test setup, and measurement system for a series of fixed caisson tests and demonstrates the consistency of the test data. The measured inline drag and transverse lift forces on the fixed caisson at different drafts are presented and the effect of the fluid velocity and flow vorticity on the frequency contents in the forces is discussed. The interaction effect of the neighboring existing pier on the current forces on the caisson is investigated. Since the measured forces were applied in the design analysis of the caissons, the scaling effect of the model test is also discussed. This paper is accompanied by two other papers, which form a group of three papers related to the project describing the current excitation on the caisson and the associated caisson responses. The other two papers in succession are by Chakrabarti et al. (J. Offshore Mech. Arct. Eng., to be published) and Chakrabarti and McBride (J. Offshore Mech. Arct. Eng., to be published). The paper by Chakrabarti et al. describes the numerical computation of the current forces on the caisson by a three-dimensional analysis, while the paper by Chakrabarti and McBride uses the information from these two papers to determine the motion response of the caissons and the mooring line tensions.
13
GONZALEZ-ESCRIVA, Jose A., Josep R. MEDINA e Joaquin M. GARRIDO. "PORT RESONANCE MITIGATION MODELED INTRODUCING ARJ-R STRUCTURES". Coastal Engineering Proceedings, n. 36v (28 dicembre 2020): 38. http://dx.doi.org/10.9753/icce.v36v.structures.38.
Testo completoAbstract (sommario):
ARJ-R caissons are based on the "long-circuit" concept (Medina et al, 2016) that allows the extension of the destructive wave interference mechanism to mitigate low frequency oscillations without enlarging the width of the caisson. The performance of the ARJ-R caissons is referred to its reflection coefficient (Cr) which was obtained through large-scale physical model tests (Gonzalez-Escriva et al, 2018). In this paper, the effectiveness of Anti-Reflective Jarlan-type structures for Port Resonance mitigation (ARJ-R) has been assessed numerically for the port of Denia (Spain). ARJ-R structures are constructible, with similar dimensions as conventional vertical quay caissons and with a similar cost (15percent more than conventional vertical caisson).Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/LomQEVpvjik
14
Zhu, Bin, Jia-lin Dai, De-qiong Kong, Ling-yun Feng e Yun-min Chen. "Centrifuge modelling of uplift response of suction caisson groups in soft clay". Canadian Geotechnical Journal 57, n. 9 (settembre 2020): 1294–303. http://dx.doi.org/10.1139/cgj-2018-0838.
Testo completoAbstract (sommario):
This paper describes a program of centrifuge model tests on the uplift behaviour of suction caisson foundations. The parameters considered were the loading rate, caisson diameter (D), soil strength profile, and type of footing (i.e., mono-caisson and tetra-caissons group). The loading responses were examined in terms of total uplift resistance, suction beneath the caisson lid, and the vertical displacements of the caisson and at the soil surface. There exists a critical uplift displacement, approximately 0.02D and 0.01D for the mono-caisson and the tetra-caissons groups, respectively, at which a turning point can be identified in the load–displacement curve. This was found to be attributed to the adhesion on the caisson–soil interface reaching a peak response and then dropping. Of interest is that the tetra-caissons group exhibits much greater normalized uplift resistance than the mono-caisson group before reaching an uplift displacement of about 0.02D, suggesting superiority of the former in term of serviceability. However, a reversed trend was observed at greater displacement, and accordingly an empirical model was derived to quantify the shadowing effect of caisson groups. Regarding the cyclic response, several cycles of large-amplitude loading are sufficient to reduce the ultimate bearing capacity of caisson(s) to below the self-weight of the inner soil plug(s), indicating a transition of failure mechanism.
15
Cihan, Kubilay, Havva Anıl Arı, Yalçın Yüksel e Mehmet Berilgen. "NUMERICAL ANALYSIS OF DEFORMATION BASED DESIGN FOR CAISSONS". Coastal Engineering Proceedings 1, n. 32 (29 gennaio 2011): 18. http://dx.doi.org/10.9753/icce.v32.posters.18.
Testo completoAbstract (sommario):
Caissons are used effectively to protect shorelines and harbours by reflecting wave energy towards the open sea. The successful performance of caissons has been attributed to experience and continued research. The seismic design for caissons is important since the functional loss of ports may cause severe economic loss. It is necessary to conduct a seismic design in terms of functionality so that cargo handling facilities may continue to function even after severe earthquakes. Relative displacement is an important index when the functionality of crane rails on caisson-type quay walls is discussed. Recent design codes for caissons demand performance-based designs. These codes require that the seismic performance of the walls be evaluated based on the permanent wall displacement after an earthquake. The seismic displacement of the caissons can be evaluated by dynamic analyses or simplified dynamic analyses based on the Newmark sliding block concept. Comprehensive results for the dynamic behaviour of soil and caissons can be obtained from dynamic analyses. In this study, the dynamic behaviour of soil and caissons were investigated by using FEM method and results were compared with experimental results from previous study existed in literature.
16
Chakrabarti, Subrata K., e Mark McBride. "Station-Keeping Tests of Moored Caisson in Strong Current". Journal of Offshore Mechanics and Arctic Engineering 127, n. 4 (27 gennaio 2005): 315–21. http://dx.doi.org/10.1115/1.2073087.
Testo completoAbstract (sommario):
A new suspension bridge is being built over the Tacoma Narrows, Washington. The bridge will be placed on a structure mounted on two large concrete caissons. The caissons are being constructed in a floating position by pouring concrete at site. During this construction period, the floating caissons are moored in place and will be subject to high currents in the Narrows at a range of drafts. In order to investigate the motions of the caisson and the mooring line loads, physical model tests were performed at a scale of 1:100 at HR Wallingford (HRW). The actual bottom contours of the Narrows near the construction site were duplicated in the model. The catenary mooring lines were highly nonlinear. The current forces and moments on the floating caisson included steady and oscillating components due to flow separation and vortex shedding. There is an existing bridge mounted on two piers in the vicinity of the new caissons, which introduced an appreciable flow interference effect. The tests were conducted in both the ebb and flood flow directions so that the effect of the shadowing of the caisson-pier pair could be studied in the tests. The recorded results of the elastic mooring tests were compared in terms of the maximum measured tensions with a time-domain dynamic motion simulation program, MOTSIM. The results of this comparison are presented in this paper.
17
Nakamura, Tomoaki, Naoto Nagayama, Yong-Hwan Cho, Norimi Mizutani, Yoshinosuke Kurahara e Masahide Takeda. "Motion of Floating Caisson with Extended Bottom Slab under Regular and Irregular Waves". Journal of Marine Science and Engineering 9, n. 10 (15 ottobre 2021): 1129. http://dx.doi.org/10.3390/jmse9101129.
Testo completoAbstract (sommario):
Floating caissons may oscillate primarily due to ocean waves during towing operations. Reducing the oscillation based on the extension part (footing) of the bottom slab of the caissons can efficiently increase the safety of towing maneuvers. However, the influence of the footing length on the motion of floating caissons has not been adequately studied. This study investigates this topic through hydraulic model experiments and numerical simulations. Experimental results for regular waves show that the rotational motion (pitch) of the caisson around the wave crest direction increases owing to resonance. This suggests that the pitch could be reduced by designing caissons, such that resonance may be prevented along the footing length. In the numerical simulations of irregular waves, the Fourier amplitudes of the heave and pitch show that the footings amplify their low-frequency components and reduce their high-frequency components. Furthermore, the significant total amplitudes of the heave and pitch show a different trend from that of the regular waves observed in the hydraulic model experiments. This suggests that it is essential to examine the motion of a caisson under irregular waves when assessing the effect of footings in an actual marine environment.
18
Faraci, Carla, Biagio Cammaroto, Luca Cavallaro e Enrico Foti. "WAVE REFLECTION GENERATED BY CAISSONS WITH INTERNAL RUBBLE MOUND OF VARIABLE SLOPE". Coastal Engineering Proceedings 1, n. 33 (14 dicembre 2012): 51. http://dx.doi.org/10.9753/icce.v33.structures.51.
Testo completoAbstract (sommario):
The paper reports on an experimental campaign focused on the performances of prefabricated caissons with internal rubble mound (combined caissons) in terms of incident wave energy reduction. The frontal opening and the chamber width of the caisson were changed in order to find the optimal design dimensions allowing the reflection coefficient to be reduced as much as possible. As expected, the best performances of the combined caisson occur when the rubble mound slope is gentler. The experimental results were also compared with an analytical model available in literature; such a comparison showed that the combined caisson exhibits a smaller reflection than predicted as far as wave periods higher than 8-9 s at a prototype scale are concerned.
19
Wang, Y. Z. "Motion and stability of caisson breakwaters under breaking wave impact". Canadian Journal of Civil Engineering 28, n. 6 (1 dicembre 2001): 960–68. http://dx.doi.org/10.1139/l01-040.
Testo completoAbstract (sommario):
The possible motions of caisson breakwaters under dynamic load excitation include vibrating motion, vibratingsliding motion, and vibratingrocking motion. Three models are presented in this paper and are used to simulate the histories of vibratingslidingrocking motions of caissons under breaking wave impact. The effect of the dynamic characteristics of the caissonfoundation system and the motions on the displacement, rotation, sliding force, and overturning moment of caissons are investigated. It is shown that the sliding force of the caisson is different from the breaking wave force directly acting on the caisson due to the motion of the caisson and the sliding motion or rocking motion of the caisson can limit the sliding force or overturning moment of the caisson to a certain value. The sliding force never exceeds the friction force between the caisson and the foundation, and the overturning moment never exceeds the stability moment of the caisson. It is concluded that the wave conditions, the dynamic characteristics, and the motions of the caissonfoundation system should be considered in design.Key words: caisson breakwater, breaking wave, vibrating, sliding, rocking.
20
Garrido, Joaquín María, Daniel Ponce de León, Antonio Berruguete, Silvia Martínez, José Manuel, Lisardo Fort, Diego Yagüe, Jose Alberto González-Escrivá e Josep R. Medina. "STUDY OF REFLECTION OF NEW LOW-REFLECTIVITY QUAY WALL CAISSON". Coastal Engineering Proceedings 1, n. 32 (31 gennaio 2011): 27. http://dx.doi.org/10.9753/icce.v32.structures.27.
Testo completoAbstract (sommario):
This paper presents a new low-reflectivity quay wall caisson based on the formation of cell circuits. The cell circuit lengths can be adapted to the specific wave climate conditions at the construction site to obtain the best performance. Results from physical model tests of conventional and cell circuit caissons are described, as well as the construction process and steel reinforcement, which turns out to be quite similar to highly reflective conventional caissons. Neural Network (NN) models are used to describe the nonlinear relationship observed between experimental coefficients of reflection (CR) and the structural and wave conditions for the new low reflectivity quay wall caisson.
21
Ren, Xiaozhong, e Yuxiang Ma. "Numerical Simulations for Nonlinear Waves Interaction with Multiple Perforated Quasi-Ellipse Caissons". Mathematical Problems in Engineering 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/895673.
Testo completoAbstract (sommario):
A three-dimensional numerical flume is developed to study cnoidal wave interaction with multiple arranged perforated quasi-ellipse caissons. The continuity equation and the Navier-Stokes equations are used as the governing equation, and the VOF method is adopted to capture the free surface elevation. The equations are discretized on staggered cells and then solved using a finite difference method. The generation and propagation of cnoidal waves in the numerical flume are tested first. And the ability of the present model to simulate interactions between waves and structures is verified by known experimental results. Then cnoidal waves with varying incident wave height and period are generated and interact with multiple quasi-ellipse caissons with and without perforation. It is found that the perforation plays an effective role in reducing wave runup/rundown and wave forces on the caissons. The wave forces on caissons reduce with the decreasing incident wave period. The influence of the transverse distance of multiple caissons on wave forces is also investigated. A closer transverse distance between caissons can produce larger wave forces. But when relative adjacent distanceL/D(Lis the transverse distance andDis the width of the quasi-ellipse caisson) is larger than 3, the effect of adjacent distance is limited.
22
Chakrabarti, Subrata K., Kristian K. Debus, Jonathan Berkoe e Brigette Rosendall. "CFD Analysis of Current-Induced Loads on Large Caisson at Supercritical Reynolds Number". Journal of Offshore Mechanics and Arctic Engineering 127, n. 2 (23 novembre 2004): 104–11. http://dx.doi.org/10.1115/1.1894409.
Testo completoAbstract (sommario):
The newly constructed Tacoma Narrows Bridge Piers represent large concrete floating caissons during their construction. For designing their mooring system the current force applied on the caissons in the Narrows must be known. The flow field around the caisson is highly complex and the calculation of the current load on the caisson by analytical means is difficult. On the other hand, model tests suffer from the distortion in the Reynolds number. Therefore, a two-prong approach was undertaken. Besides the fixed model test of the caissons for current forces, a CFD analysis of the flow around the caisson is chosen. A three-dimensional CFD approach is considered more appropriate than a two-dimensional one, since the bottom contour at the site is irregular and water depth is rather shallow. This paper discusses the CFD method and the results obtained from such analysis. The numerical analysis was carried out in both ebb and flood flow of the tidal current in the basin. One of the difficulties of the computational method is the very high Reynolds number encountered by the large current and large size of the caisson. The analysis is performed in both model and full scales so that the difference in the results may be investigated. Also, since the model test data are available, comparisons are made between the CFD and model test results on the drag and lift forces on the caisson.
23
Wang, Mingyuan, Xiaoke Liu, Xinglei Cheng, Qun Lu, Jiaqing Lu e Miao Wang. "Penetration and Pullout Capacity of Low-Skirted Suction Caissons". Shock and Vibration 2021 (4 settembre 2021): 1–12. http://dx.doi.org/10.1155/2021/2263810.
Testo completoAbstract (sommario):
The bearing capacity of suction caissons is the key to the design of offshore structures. A new type of cross-shaped low-skirted suction caisson is invented to effectively improve the bearing capacity, considering inevitable “soil plug” phenomenon. The behaviors of penetration and pullout for new low-skirted suction caisson are investigated by performing model tests. A new formula for calculating the penetration resistance is suggested based on the limit equilibrium theory and the test data, which can consider the change of the lateral area of the suction caisson during penetration. The behaviors of low-skirted suction caisson under inclined loading are analyzed by carrying out finite element simulation. The effects of loading angles and loading positions on the ultimate bearing capacity and failure mechanism of low-skirted suction caissons are discussed. The research results can provide a reference for the design of suction bucket foundation for offshore structures.
24
Chen, Xuefeng, Yucheng Li e Liu Long. "SIMULATION OF IRREGULAR WAVE PRESSURE ON PERFORATED BREAKWATERS". Coastal Engineering Proceedings 1, n. 32 (21 gennaio 2011): 29. http://dx.doi.org/10.9753/icce.v32.structures.29.
Testo completoAbstract (sommario):
In this paper, the wave pressures on the perforated caissons breakwaters are investigated. The front wall of the perforated caissons is usually perforated above a certain water level considering the stability of the structure, and the chamber of the perforated caisson is filled with rock. Based on the RANS and k- equations, the numerical method to simulate the interaction of the irregular wave with the perforated breakwaters is researched. Moreover, the wave pressures distribution on the front perforated wall and the back wall are discussed through the numerical calculations, respectively. Then, the simplified formulas to compute the wave pressures on the different position of perforated caisson are obtained from experimental data by using the least-squares method.
25
Hao, Jiawei, Dietao Ding, Jiawen Li e Ji Huang. "The Wave Amplification Mechanism of Resonant Caisson". Journal of Marine Science and Engineering 12, n. 7 (21 giugno 2024): 1038. http://dx.doi.org/10.3390/jmse12071038.
Testo completoAbstract (sommario):
Previous studies have introduced a resonant caisson designed to enhance wave energy extraction in regions with low wave energy density; however, its operational mechanism remains poorly understood. This paper seeks to elucidate the operational mechanism of the resonant caisson by leveraging Star-CCM+ for Computational Fluid Dynamics (CFD) simulations, focusing on the influence of guides and their dimensions on the water levels, flow velocities, and vortex dynamics. The findings demonstrate the remarkable wave-amplification capabilities of the resonant caisson, with the maximum amplification factor reaching 2.31 at the calculated frequency in the absence of guides. Incorporating guides and expanding their radii substantially elevate the flow rates, accelerate the water currents, and alter the vortex patterns, thereby further enhancing the amplification factor. This study will provide a reference for optimizing the design of resonant caissons and wave energy converters based on resonant caissons, thus promoting the effective use of wave energy resources.
26
Gu, Haoyang, Huakun Wang, Qiu Zhai, Weibing Feng e Jiaxiu Cao. "Study on the Dynamic Responses of a Large Caisson during Wet-Towing Transportation". Water 13, n. 2 (7 gennaio 2021): 126. http://dx.doi.org/10.3390/w13020126.
Testo completoAbstract (sommario):
Large caissons are extensively applied as deep-water foundations in marine engineering. In fact, caissons are generally prefabricated and transported to project site by wet towing. Motion responses of large caissons and those occurring during the towing process were investigated, and CO2 emissions under various conditions were calculated. These are all considered to ensure towing safety and environmental protection. The caisson resistance coefficient was simulated via Ansys Fluent software. The effects of towrope length, towing speed, and drift depth on the motion responses of caissons under the combined action of wind and wave were evaluated via Ansys AQWA software. Maximum heave value was dominantly affected by rope length and draft depth, and its fluctuation was highly influenced by towing speed and draft depth. However, all of the above mentioned factors had insignificant influences on pitch response. When towing existed, rope tension was rapidly increased from zero to a constant value that depended on towing speed and drift depth. However, the speed of achieving this stable phase depended on the length of the towrope.
27
Gu, Haoyang, Huakun Wang, Qiu Zhai, Weibing Feng e Jiaxiu Cao. "Study on the Dynamic Responses of a Large Caisson during Wet-Towing Transportation". Water 13, n. 2 (7 gennaio 2021): 126. http://dx.doi.org/10.3390/w13020126.
Testo completoAbstract (sommario):
Large caissons are extensively applied as deep-water foundations in marine engineering. In fact, caissons are generally prefabricated and transported to project site by wet towing. Motion responses of large caissons and those occurring during the towing process were investigated, and CO2 emissions under various conditions were calculated. These are all considered to ensure towing safety and environmental protection. The caisson resistance coefficient was simulated via Ansys Fluent software. The effects of towrope length, towing speed, and drift depth on the motion responses of caissons under the combined action of wind and wave were evaluated via Ansys AQWA software. Maximum heave value was dominantly affected by rope length and draft depth, and its fluctuation was highly influenced by towing speed and draft depth. However, all of the above mentioned factors had insignificant influences on pitch response. When towing existed, rope tension was rapidly increased from zero to a constant value that depended on towing speed and drift depth. However, the speed of achieving this stable phase depended on the length of the towrope.
28
Xie, Liquan, Shili Ma e Tiantian Lin. "The Seepage and Soil Plug Formation in Suction Caissons in Sand Using Visual Tests". Applied Sciences 10, n. 2 (13 gennaio 2020): 566. http://dx.doi.org/10.3390/app10020566.
Testo completoAbstract (sommario):
The rapid development of offshore wind energy in China is becoming increasingly relevant for movement toward green development. This paper presents the results of visual tests of a suction caisson used as foundation for offshore wind turbines. The distribution of hydraulic gradients of sand at the mudline in the caisson was obtained to find out the relationship with the heights of soil plugs. The relationship equation was proposed and obtained by using quadratic regression, guiding project designs, and construction. It was found that there was no soil plug in the caisson when small suction was applied during the suction penetration. The relationship between the heights of the soil plugs and the hydraulic gradient of the soil was proposed and obtained by using quadratic regression to predict (roughly) the height of soil plugs in suction caissons in sand during suction penetration. The influence of settlement outside caissons on the soil plug was found to decrease as the buried depth rose.
29
Shi, Ping. "Model Tests on Characteristic of Suction Caissons in Saturated Fine Sand Under Intermittent Loading". Polish Maritime Research 25, s3 (1 dicembre 2018): 127–35. http://dx.doi.org/10.2478/pomr-2018-0121.
Testo completoAbstract (sommario):
Abstract Suction caissons are often used for the caissons of both offshore oil platforms and offshore wind power projects because of their advantages of simple construction, economical cost, and reusability. In this study, model tests were conducted in sand in order to investigate the effects of the caisson installation method on the penetration depth and the critical suction. Results of the test program showed that the method of changing the frequency of suction during different stages of the process can increase the penetration depth of the caisson. Combining with the deformation of the soil body inside and outside the caisson, the existing method for calculating the critical suction is modified, and the critical suction calculation equation of the discontinuous penetration test is proposed. Based on the test results, the calculation equation of the soil heave height can be more accurate predicted. The analysis results verify that the calculation method and the actual results are in good agreement.
30
Nabeshima, Yasuyuki. "Installation and Lateral Resistance of Model Suction Caissons in Sandy Ground". Advanced Materials Research 1030-1032 (settembre 2014): 790–97. http://dx.doi.org/10.4028/www.scientific.net/amr.1030-1032.790.
Testo completoAbstract (sommario):
Suction caissons attract the attention as the foundation of offshore wind turbines. Installation and resistance behaviors of the suction caisson are important factors for the design of foundation. An installation behavior into sandy seafloor was discussed by using a model suction caisson and the failure surfaces in the aluminum rod mass, as the model ground, subjected to lateral force were compared. Consequently, the installation of model suction caisson into sandy sea depended on the permeability of sandy seafloor and lateral resistance of suction caisson depended on the dimension of suction caisson which affected on the shape of failure surface in the ground.
31
Zhou, Hongjie, e Mark F. Randolph. "Large deformation analysis of suction caisson installation in clay". Canadian Geotechnical Journal 43, n. 12 (1 dicembre 2006): 1344–57. http://dx.doi.org/10.1139/t06-087.
Testo completoAbstract (sommario):
Large deformation finite element (LDFE) analyses were performed to study the installation of caissons by suction and jacking in normally consolidated clay. The penetration of the caisson wall was modelled between depths of one and four diameters using an axisymmetric LDFE approach, which falls in the category of arbitrary Lagrangian–Eulerian (ALE) methods. The results allowed quantification of differences in the behaviour of caissons installed entirely by jacking compared with a combination of self-weight and suction as is used in the field. For jacked installation, over the penetration range of one to four diameters, the proportion of caisson wall accommodated by inward soil flow reduced from around 45% at the start to zero at about four diameters embedment; by contrast, the proportion for suction installation stayed essentially constant, oscillating around 65% through the depth of penetration. This difference was also evident in the local incremental displacements of the soil beneath the caisson tip. During continuous penetration, the induced increases in radial and mean total stresses around the caisson wall are some 10%–15% smaller for suction installation than for jacked installation, with the difference growing with increasing penetration. In addition, an obvious difference was found in the caisson tip resistance between these two installation methods.Key words: suction caisson, clay, large deformation finite element, soil plug, total stress changes, penetration resistance, factor of safety.
32
Hiraishi, Kohshi, e Taro Arikawa. "DEVELOPMENT OF PREDICTING MOTION OF FLOATING CAISSON UNDER REGULAR AND IRREGULAR WAVES". Coastal Engineering Proceedings, n. 37 (1 settembre 2023): 32. http://dx.doi.org/10.9753/icce.v37.structures.32.
Testo completoAbstract (sommario):
Breakwaters for outer harbor facilities are considerably affected by wave conditions, rendering the control of caisson motion difficult. Its motion during breakwater installation is important to improve its operational efficiency and safety. In recent years, caisson motion has been studied using 3D solid-gas-liquid three-phase simulations. Nakamura et al. (2021) investigated the dynamic characteristics of floating caissons under regular and irregular waves. Takagi et al. (2021) studied its sway and contact with mounds when the bottom clearance was changed and demonstrated the validity of their numerical method. However, due to inevitable scale effects of the small-scale experiments and simulations, these studies require examination at a large scale. In this study, the numerical simulation developed by Arikawa et al. (2009) was used to investigate the motion characteristics of life-sized floating caissons under regular and irregular waves for case studies conducted at the Port of Kochi (Ishimi et al. 1996).
33
Shirai, Kaito, Tomoaki Nakamura, Yong-Hwan Cho, Norimi Mizutani, Yoshinosuke Kurahara e Masahide Takeda. "Development of Coupled Numerical Model between Floating Caisson and Anti-Oscillation Tanks". Journal of Marine Science and Engineering 11, n. 9 (25 agosto 2023): 1669. http://dx.doi.org/10.3390/jmse11091669.
Testo completoAbstract (sommario):
Floating caissons can oscillate owing to ocean waves when towed to an installation site. To reduce these oscillations, free-surface anti-oscillation tanks mounted on floating caissons have been proposed. However, no coupled numerical model exists between the motion of the floating caisson and fluid flow in the tanks based on computational fluid dynamics (CFD). In this study, a coupled model is developed and compared to existing physical experiments for validation. In the coupled model, the vertical and rotational motion of the floating caisson are computed as a rigid body, and the motion of the free water in the tank is computed using a CFD model. Numerical results show the predictive capability of the coupled model in terms of the rotational motion (pitch) of the floating caisson within ±20% of experimental data, regardless of the absence or presence of water in the tank. The numerical results also show that the fluid flow with complex air–water interface motion in the tank can be analyzed in detail using the coupled model. This suggests that the coupled model developed in this study is a useful tool for quantitatively assessing the effectiveness of an anti-oscillation tank for reducing the pitch of a floating caisson.
34
Sawicki, Andrzej, Łukasz Wachowski e Marek Kulczykowski. "The Pull-out Capacity of Suction Caissons in Model Investigations". Archives of Hydro-Engineering and Environmental Mechanics 63, n. 2-3 (1 dicembre 2016): 157–71. http://dx.doi.org/10.1515/heem-2016-0010.
Testo completoAbstract (sommario):
AbstractA small-scale model experiment on the pull-out resistance of suction caissons is described. The pull-out force and suction developed within the caisson in the extraction process were recorded during the experiment. A simple breakout model, together with an elementary static formulae, is applied to predict the results obtained experimentally. There is a reasonably good agreement between the experimental results and predictions. An extensive discussion of the approach applied is included. The analysis presented in this paper is original, as it differs from other approaches mentioned in this paper, and leads to acceptable predictions. At the end, the results are also compared with another approach for predicting the capacity of suction caissons.
35
Shen, Li. "Maṇḍala or Sign? Re-Examining the Significance of the “Viśvavajra” in the Caisson Ceilings of Dunhuang Mogao Caves". Religions 15, n. 7 (30 giugno 2024): 803. http://dx.doi.org/10.3390/rel15070803.
Testo completoAbstract (sommario):
This article delves into the exploration of a significant sign, the “viśvavajra”, found in the caisson ceilings of Buddhist esoteric art in Dunhuang’s Mogao Caves. These caissons, featuring the viśvavajra sign in the center, were prevalent from the mid-Tang period to the Western Xia dynasty (ninth to thirteenth centuries) and are recorded by The Overall Record of Dunhuang Mogao Grottoes under description as “Jiaochu Jingxin”. Similar caissons are also found in Western Buddhist Caves near Dunhuang, and Yulin Caves in Guazhou County, indicating a distinct regional character. Focusing on a well-preserved and intricately detailed example from Cave 361, this article aims to elucidate the specific tantric significance of the viśvavajra at the center of the caissons within the broader context of Buddhist art. Drawing from related tantras, the discussion explores how the sign and its surrounding compositions align with a particular homa (fire offering) maṇḍala, specifically the śāntika maṇḍala crucial to numerous Tantric Buddhist rituals. Furthermore, the article examines the evolution of caisson of this type of maṇḍala over time. By comparing the mid-Tang example from Cave 361 with the late Tang period’s Cave 14, a noticeable shift in format becomes apparent. The viśvavajra sign takes on new significance, embodying “the samaya of all Tathāgatas”. Ultimately, the article explores how the significance of the viśvavajra sign transforms into an allusion to Vairocana or Rocana under the Sino-Tibetan Esoteric Buddhist context in the Hexi Corridor during the early Northern Song and Western Xia dynasty.
36
Cejuela, Eduardo, Vicente Negro, Jose María del Campo, Mario Martín-Antón, M. Dolores Esteban e Jose Santos López-Gutiérrez. "Recent History, Types, and Future of Modern Caisson Technology: The Way to More Sustainable Practices". Sustainability 10, n. 11 (23 ottobre 2018): 3839. http://dx.doi.org/10.3390/su10113839.
Testo completoAbstract (sommario):
The construction of caisson breakwaters dates from ancient times (Brindisi battle and Caesarea Maritima, Roman Empire) of yore but has evolved with regards to technology and the materials available at all times (wood, gravel, and rubble mound). The growth in draught in vessels searching for deep water depths for berthing plus environmental problems have led to the 20th century facilitating the boom in vertical types and concrete caissons built in different ways (dry and floating techniques). Furthermore, structural criteria gave way to functional, environmental, and aesthetic criteria. The search for new, more efficient forms led to the construction of increasingly more complex elements including many that still require an economically viable construction system. To where will this search for new materials and forms take us? The use of composite materials could be considered, at the moment, as too expensive, but analyzing the cost with a wider approach, as Life Cycle Assessment, shows us that caissons in composite materials are cost effective and could be a solution. Furthermore, the possibility of using recyclable composites opens up big opportunities of using these materials at affordable costs. Caissons in composites or recycled composites are then a real alternative to concrete caissons. In Spain, two examples can be observed: a berthing area in Canary Island (Puerto del Rosario, South Atlantic Ocean) and a crown wall in Cartagena using polyester fiber bars (Mediterranean Sea). European policy in matters of sustainability promotes the circular economy, which means not only consider construction of caissons in recycled composites should be considered but also the comparison of all materials and construction procedures. Lastly, the calculation of the Environmental Product Declaration (EPD) should be promoted.
37
Clukey, Edward C., Charles P. Aubeny e James D. Murff. "Comparison of Analytical and Centrifuge Model Tests for Suction Caissons Subjected to Combined Loads". Journal of Offshore Mechanics and Arctic Engineering 126, n. 4 (1 novembre 2004): 364–67. http://dx.doi.org/10.1115/1.1834624.
Testo completoAbstract (sommario):
A plastic limit formulation was previously developed for estimating caisson uplift in cohesive soils under general conditions of vertical, horizontal, and inclined loading. The formulation considers the effects of soil shear strength profile, caisson aspect ratio, anchor line attachment depth, and load inclination angle. Load capacity predictions from the plastic limit analyses are compared to data measured in seven centrifuge tests in which model caissons are subjected to purely vertical and inclined loads of various orientations. The effect of a bevel at the caisson tip is also investigated. Comparisons are also made to finite element predictions.
38
Wallace, Jeff F., e Cassandra J. Rutherford. "Response of suction caissons for tidal current turbine applications in soft clay to monotonic and cyclic vertical loading". Canadian Geotechnical Journal 55, n. 4 (aprile 2018): 551–62. http://dx.doi.org/10.1139/cgj-2016-0133.
Testo completoAbstract (sommario):
In soft marine clays, suction caissons provide a foundation system for tidal current turbines that further promote the sustainable nature of the system by allowing for their removal at the end of the structure’s design life. When configured as a multipod, the moment loads resulting from the horizontal flow of water will be transferred to the suction caissons as compression–uplift loads on opposing foundation legs. The behavior of a suction caisson in soft clay was investigated at aspect ratios of 1 and 2 under monotonic and cyclic vertical loading applicable to multipod-supported tidal current turbine design. Installation and solely monotonic vertical load tests indicated lower back-calculated adhesion factor, α, values and higher back-calculated bearing capacity factor, Nc, values than design standards recommend. The capacity and stiffness response of the foundation after undergoing cyclic loading was found to be largely dependent on the magnitude of displacement the foundation underwent during cyclic loading. Additionally, a threshold of elastic foundation response was observed during cyclic loading defined by a cyclic displacement amplitude. These results indicate serviceability constraints will be critical in the design of suction caisson foundations for tidal current turbine applications.
39
Jin, Shu Cheng, Yong Tao Zhang e Qi He Wu. "A Study on the Failure Mechanism of Suction Caisson under Vertical Load". Applied Mechanics and Materials 256-259 (dicembre 2012): 1985–89. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.1985.
Testo completoAbstract (sommario):
As a new type of deep water offshore foundation, suction caisson is widely used to offshore structures. However, the current methods of evaluation and design cannot meet the increasing requirement of engineering practice. In this dissertation, the studies are emphasized on finite element method for analyzing the suction caisson bearing capacity behavior and the failure mechanism under the vertical load. Based on studying the vertical bearing behavior of caissons with different ratio of length to diameter L / D, it shown that as L / D increases, the vertical bearing capacity growth slowed.
40
Song, Tiancheng, Albert Cheng, Eugene Khoo, Yaodong Zhang, Wan Sin Chen e Robin Liao Bin Kui. "CAISSON DESIGN AND VERIFICATION OF FRICTION COEFFICIENT OF CAISSON FOUNDATION FOR TUAS PORT PHASE 1". Coastal Engineering Proceedings, n. 37 (1 settembre 2023): 26. http://dx.doi.org/10.9753/icce.v37.papers.26.
Testo completoAbstract (sommario):
Reinforced precast concrete caisson has been selected as wharf front structure for the project of Tuas Port Phase 1 in Singapore. The caisson structure and foundation were designed to withstand various loading cases comprising loads during both construction and operation stages. It was identified that sliding failure mode of the caisson structures could be one of the critical design checks. The friction tests were conducted under various conditions to assess the Coefficient of Friction (m) between rock mound surface and concrete slab of caissons. The results show that the design value mu of 0.6 for rock mound and concrete interface could be achieved for normal flat concrete surface.
41
Huang, Maosong, Chenrong Zhang, Linlong Mu e Weiming Gong. "Analysis of anchor foundation with root caissons loaded in nonhomogeneous soils". Canadian Geotechnical Journal 48, n. 2 (febbraio 2011): 234–46. http://dx.doi.org/10.1139/t10-046.
Testo completoAbstract (sommario):
This paper presents a novel type of deep foundation — an anchor foundation with root caissons, which improve the soil–caisson interaction using penetrating roots. A simplified analytical procedure is proposed for calculating responses of the new anchor foundation subjected to combined vertical, horizontal, and moment loadings. Caisson–soil interaction is simulated by a Winkler subgrade reaction model, with an improved Winkler spring constant to consider the reinforcement effect of roots. The method incorporates limiting soil stress to investigate soil nonlinear behavior and a transfer matrix to represent nonhomogeneous soils, with a passive caisson model accounting for group effects. The effectiveness of the present approach is evaluated by comparison with full-scale field load tests and a finite element analysis on a small-scale anchor foundation to give a preliminary design guideline for the Ma’anshan Yangtze River Bridge in China.
42
Wei, Ming Hui, Guo Bao Li e Peng Wei Xiao. "Rehabilitation Technology for Excessive Large Gap of Joint between Caissons of Gravity Wharf". Applied Mechanics and Materials 501-504 (gennaio 2014): 1032–38. http://dx.doi.org/10.4028/www.scientific.net/amm.501-504.1032.
Testo completoAbstract (sommario):
Excessive large gap of joint between caissons easily lead to the rear backfill leaking into harbor basin, to cause a differential settlement of the rear terminals and even affect the structural stability. With the case about caisson wharf of a harbor in southern China, this paper puts forward a rehabilitation technology of caisson joints with mold bag concrete as the major filler. The key technologies are introduced in detail including the mold bag production and installation, the height computation of laminated pouring of concrete and underwater concreting, etc. This technical maintenance is reasonable in economy and practicable in technology, worthy of promotion.
43
Mohamedelhassan, Eltayeb, Kevin Curtain, Matt Fenos, Kevin Girard, Anthony Provenzano e Wesley Tabaczuk. "Electrokinetic Treatment for Model Caissons with Increasing Dimensions". Advances in Civil Engineering 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/153123.
Testo completoAbstract (sommario):
Electrokinetic treatment has been known in geotechnical engineering for over six decades, yet, the technique is rarely used. This stems from the absence of design guidelines and specifications for electrokinetic treatment systems. An important issue that need to be investigated and understood in order to devise guidelines from experimental results is the effect of the foundation element size on the outcome of the treatment. Also important is determining the optimum distance between the electrodes and estimating the energy consumption prior to treatment. This experimental study is a preliminary step in understanding some of the issues critical for the guidelines and specifications. Four model caissons with surface areas between 16000 and 128000 mm2were embedded in soft clayey soil under water and treated for 168 hr with a dc voltage of 6 V. From the results, a distance between the anode (model caisson) and the cathode equal 0.25 times the outside diameter of the model caisson was identified as optimum. Relationships between the surface area and axial capacity of the model caisson and the surface area and energy consumption were presented. The equations can be used to preliminary estimate the load capacity and the energy consumption for full-scale applications.
44
Esteban, Miguel, Hiroshi Takagi e Tomoya Shibayama. "MODIFIED GODA FORMULA TO SIMULATE SLIDING OF COMPOSITE CAISSON BREAKWATER". Coastal Engineering Proceedings 1, n. 32 (31 gennaio 2011): 47. http://dx.doi.org/10.9753/icce.v32.structures.47.
Testo completoAbstract (sommario):
Caisson breakwaters can continue to maintain their function if a limited amount of sliding or tilting occurs. Although this has been the focus of much research during the last years, little attention has been paid to the design of composite caisson breakwaters (i.e. caissons protected with armour layers). The present paper outlines laboratory experiments that were carried out to propose a modification of the Goda formula (1974) that takes into account the increased pressures that can be exerted by waves due incomplete armour layers at the seaside face of the caisson. The effect that this modification can have on the expected deformations in the rubble mound after one storm are also evaluated by means of a Monte Carlo Simulation, showing how incomplete armour layers will result in much greater expected vertical movements in the caisson.
45
Wang, Jian, Li Sha Chai e Hao Wu. "Numerical Simulation on the Sinking Process of Open Caisson with Particle Flow Code (PFC)". Advanced Materials Research 838-841 (novembre 2013): 831–34. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.831.
Testo completoAbstract (sommario):
Sidewall pressure is important to open caisson design. However, FEM simulation for the sinking process of open caisson is quite difficult due to extremely large deformation including soil flow and solid boundary movement. In order to overcome this problem, Particle Flow Code (PFC), which is based upon discrete element method (DEM), was applied to simulate the whole sinking process of an open caisson using proposed load servo mechanism, and the variations of the sidewall pressure with sinking depth and elevation were investigated. The outcomes agree well with the in-situ observation data and the indoor experiment data, which verifies the feasibility of modeling the sinking process of open caissons using PFC and further studying their soil-structure interaction mechanisms from the microscopic prospect.
46
Liu, Wei, Zhihuai Huang e Mi Zhou. "Numerical Study on the Behavior of Square Stiffened Caissons Penetrating into Normally Consolidated Clay". Advances in Civil Engineering 2021 (30 agosto 2021): 1–10. http://dx.doi.org/10.1155/2021/1607854.
Testo completoAbstract (sommario):
Significant difference between predicted and measured installation resistance of stiffened suction caissons was identified due to the existing uncertainty regarding the mobilized soil flow mechanisms. This paper describes an extensive investigation of square stiffened caisson penetration in nonhomogeneous clays undertaken through large deformation FE (LDFE) analysis to identify the soil flow mechanisms around and between lateral ring stiffeners. A detailed parametric study has been carried out, exploring a range of nondimensional parameters related to stiffened caisson geometry, caisson roughness, and soil strength. The LDFE results were compared with centrifuge test data in terms of soil flow mechanisms, with good agreement obtained. Two interesting features of soil flow inside the caisson were observed including soil backflow into the gaps between the embedded stiffeners and soil heaving at the surface. It shows that the cavity depth can reach ∼5 m. Finally, simple expressions were proposed for estimating the critical depths of soil backflow and cavity formation.
47
Lee, Byeong Wook, Jae-Sang Jung, Woo-Sun Park e Jae-Seon Yoon. "Wave Force Characteristics and Stability of Detached Breakwaters Consisting of Open Cell Caissons Interlocked via Crushed Stones". Water 12, n. 10 (15 ottobre 2020): 2873. http://dx.doi.org/10.3390/w12102873.
Testo completoAbstract (sommario):
The maximum external force acting on a long continuous harbor structure can be reduced by controlling the phase difference of forces acting longitudinally. This strategy can be used to increase the structural stability of breakwaters consisting of caissons. Breakwaters have been developed using interlocking caissons to effectively respond to the constant increase in wave height due to climate change. In this study, we investigated the wave force characteristics and stability of a detached breakwater consisting of open cell caissons interlocked via crushed stones. We performed wave basin experiments and compared the results with analytical solutions of linear diffraction waves. The results revealed that the maximum wave force acting on the front of the breakwater decreased as the incident angle increased, reducing by as much as 79% for an incident angle of 30°. Although the variability of the maximum wave force for each caisson is large owing to the influence of the diffracted waves, the maximum wave force acting on the entire detached breakwater was not significantly affected by this variability. The analytical solutions based on linear wave theory agreed with the experimental results, indicating that the findings can be applied to actual designs. The structural stability of the breakwater was enhanced, even for low incident wave angles, compared to that of a single integral structure, as the frictional resistance produced by the sliding structure increased due to the shear resistance between the filled crushed stones and the rubble mound.
48
Perminov, Nickolai. "SIMULATION OF A DEFECTLESS LIFECYCLE OF UNIQUE UNDERGROUND STRUCTURES OF THE SEWAGE SYSTEM AT THE STAGE OF THEIR CONSTRUCTION IN DIFFICULT SOIL CONDITIONS". International Journal for Computational Civil and Structural Engineering 15, n. 1 (25 marzo 2019): 119–30. http://dx.doi.org/10.22337/2587-9618-2019-15-1-119-130.
Testo completoAbstract (sommario):
Emperor Alexander I Saint-Petersburg State Transport University, Saint-Petersburg, RUSSIA
Abstract: Simulation of the parameters of a defectless lifecycle of large caissons at the stage of their plunging into heterogeneous soil milieu allows considerable expansion of the area of rational use of underground areas of megacities for deep transport facilities and engineering infrastructure due to provision of structural safety and sustainable operation of a special underground structure. Mega sizes of an RC caisson allow creating open underground areas, unique in volumes and deepness. The analysis of behavior of a massive gravitational fencing caisson at its incrementing and plunging into heterogenenous soil milieu allowed identifying the nature of its non-linear and unsteady behavior. Unsteadiness of the processes of interaction of a large structure and soil milieu accompanied by geometrical changeability causes the necessity to create methods of adaptive control of strain- stress behavior of the system “gravitational large body - heterogeneous host medium” for decreasing aggravating influence of these effects on strength, deformability and reliability of the structure at the subsequent stages of its lifecycle. Due to joint step-by-step implementation of geotechnical and structural calculations a history of the processes of caisson-soil milieu interaction is modeled and the parameters of adaptive control of strain-stress behavior are predicted, thus providing conditions of controlled lowering. The paper demonstrates results of consistent implementation of the given concept at the lifecycle stages of the unique caissons for the sewage system of the megacity beginning from numerical modeling during design to computer models of control of strain-stress behavior of the system “large caisson - soil bulk” using the methods of geotechnology with subsequent monitoring provision of the defectless stage of construction.
49
Wang, He, Rui Wang e Jian-Min Zhang. "Solid-Fluid Coupled Numerical Analysis of Suction Caisson Installation in Sand". Journal of Marine Science and Engineering 9, n. 7 (26 giugno 2021): 704. http://dx.doi.org/10.3390/jmse9070704.
Testo completoAbstract (sommario):
Suction caissons are widely used foundations in offshore engineering. The change in excess pore pressure and seepage field caused by penetration and suction significantly affects the soil resistance around the caisson wall and tip, and also affects the deformation of the soil within and adjacent to the caisson. This study uses Arbitrary Lagrangian–Eulerian (ALE) large deformation solid-fluid coupled FEM to investigate the changes in suction pressure and the seepage field during the process of the suction caisson installation in sand. A nonlinear Drucker-Prager model is used to model soil, while Coulomb friction is applied at the soil-caisson interface. The ALE solid-fluid coupled FEM is shown to be able to successfully simulate both jacked penetration and suction penetration caisson installation processes in sand observed in centrifuge tests. The difference in penetration resistance for jacked and suction installation is found to be caused by the seepage and excess pore pressure generated during the suction caisson installation, highlighting the importance of using solid-fluid coupled effective stress-based analysis to consider seepage in the evaluation of suction caisson penetration.
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Yu, Chen. "Numerical simulation of pounding damage to caisson under storm surge". E3S Web of Conferences 38 (2018): 03046. http://dx.doi.org/10.1051/e3sconf/20183803046.
Testo completoAbstract (sommario):
In this paper, a new method for the numerical simulation of structural model is proposed，which is employed to analyze the pounding response of caissons subjected to storm surge loads．According to the new method，the simulation process is divided into two steps. Firstly, the wave propagation caused by storm surge is simulated by the wave-generating tool of Flow-3D, and recording the wave force time history on the caisson. Secondly，a refined 3D finite element model of caisson is established，and the wave force load is applied on the caisson according to the measured data in the first step for further analysis of structural pounding response using the explicit solver of LSDYNA. The whole simulation of pounding response of a caisson caused by “Sha Lijia” typhoon is carried out. The results show that the different wave direction results in the different angle caisson collisions, which will lead to different failure mode of caisson, and when the angle of 60 between wave direction and front/back wall is simulated, the numerical pounding failure mode is consistent with the situation.