Mooring Dolphins Research Articles

Structure planning of 13470 DWT capacity jetty on Liquid Berth II Caspian Sea, Turkmenistan

Liquified Natural Gas is one of the products produced from refineries in the Caspian Sea. LNG production increases due to demand, causing the addition of new offshore platforms. To provide loading and unloading services for LNG, a special dock is needed, for this reason a special liquid bulk jetty with a capacity of 13470 DWT is planned. Structural planning using STAADPRO V8i Select Series 6 software, using British standards in planning. The jetty structure is expected to be strong against the loads that work due to environmental conditions and ship impacts. Structural analysis is carried out by comparing the structure’s Unity Check Ratio value with the Unity Check Ratio permitted based on applicable standards. The result is that the structure is able to withstand the working load with details of 4 Breasting Dolphin structures, 2 Mooring Dolphin structures, 1 Jetty Head Platform structure, and 1 Trestle structure.

Ice-Induced Vibration Reduction on a Mooring Dolphin Platform Using an Isolation Cone System

Ice-Induced Vibration Reduction on a Mooring Dolphin Platform Using an Isolation Cone System

Dolphin Mooring Structure Assessment PT. Smelting Gresik Due to Being Hit by a Mud Barge as a Basis for Repairing Structural Elements

A wharf or harbor is a complex of buildings connecting land and sea which functions as a place for mooring or docking of ships that will carry out the loading and unloading of goods or the boarding and falling of people (passengers) to and from the ship. Because the structure of the wharf is in the sea, incidents can occur either due to natural or human error. One of the incidents occurred at the mooring dolphin owned by PT. Smelting which was hit by a Mud Barge resulting in some damage to the structure. The case study taken is the Assessment activity on the Dolphin Mooring Structure owned by PT. Smelting. The assessment started by conducting a visual survey and the results showed that the damage occurred in the form of spalling and cracks in the concrete elements and also the peeling of the coating layer on the SPP. Furthermore, conducting tests in the field in the form of a UPV test and the results obtained that the density classification of the concrete is in a fairly good condition and the depth of the cracks that occur is still less than the minimum cover thickness. After that, under water testing was also carried out in the form of Thickness test and PIT, each of which resulted in the condition of the SPP pole still being in Fairly Good condition. And the last is destructive testing which is then used as a compressive test sample and the result is that the quality of the existing concrete still meets the quality limits for fc' 30 MPa according to SNI 6880-2016 code 1.5.6.2. Based on the tests that have been carried out, the Mooring structure is still able to function as it should, with some repairs to the damaged structures. For structures that are damaged by cracks, the suggestion for improvement that needs to be done is to inject using epoxy and for structures that are damaged by cracking & spalling, the suggestion for repairs that needs to be done is to do injection using grouting. Whereas in the SPP pole structure, the suggestion for improvement that needs to be done is to restore the initial layer consisting of HDPE and FRP Wrap. The Catwalk structure did not suffer any damage, it's just that the placement part failed due to corrosion and needed to be renewed. Based on several suggestions for improvements that need to be made, it can be estimated that the time for carrying out the work is 2 months or 60 calendar days.

ANALISIS STRUKTUR MOORING DOLPHIN KAPASITAS KAPAL 2000 GT (STUDI KASUS PELABUHAN MUNSE SULAWESI TENGGARA)

Sea transportation is the main transportation used by residents in the islands. The development of marine transportation facilities is expensive to support these activities. Therefore, several alternatives are needed to streamline construction costs, one of which is the construction of a pier using a mooring dolphin. The purpose of this study is to calculate the structural strength of the mooring dolphin with a ship capacity of 2000 GT at Munse Port, Southeast Sulawesi Province. Structural analysis is carried out by analyzing pile capacity and joint displacement analysis. The calculation of the strength of the pile elements at the pier was analyzed using the SAP 2000 program. For soil which is modeled as an elastic support, the ability to support the load depends on the magnitude of the modulus of subgrade reaction from the soil. Embedded pile modeling is modeled with a nonlinear spring force. The results of the analysis by analyzing the capacity of piles with dimensions of 508 mm with a thickness of 12 mm resulted in a capacity ratio of 0.72. The results of the analysis of joint displacement in service or operational conditions are 37.09 mm and in earthquake conditions, they are 13.01 mm.

Air Dispersion Modelling of Coal Particles Released During Handling of Cargo at Port

Mormugao Port Trust (MPT) handles 1087 t/h of coal with the help of 6 mooring dolphins situated at around 600-m distance in sea from the port next to the city of Vasco da Gama, Goa, India. During the said operations, the particles are released at lower height (2 to 5 m from sea water level) unlike other emissions. Since the city is situated next to the port, particles released during the handling of coal reach the Vasco city due to dispersion and affect health of the people in the city. The objective of this study was to identify the key variables which affect the dispersion of the particles released during coal loading and unloading operations. Detailed simulation studies are carried out to study the effect of wind speed, atmospheric temperature, atmospheric humidity, moisture content of coal, and the release height of the material from cranes, on dispersion of particles. For this purpose AERMOD software was used. All the necessary data required for the study was collected from Mormugao Port Trust, Vasco, Goa. Wind speed and moisture content of materials are key variables identified as they influence the dispersion significantly. With wind speeds greater than 8 m/s, the concentrations of PM10 and PM2.5 exceed beyond permissible limits up to 1 km radius. Variation in release height from 1 to 3 m does not have significant effect on particle dispersion. Change in atmospheric temperature and atmospheric humidity has no influence on dispersion of particles. The model results are validated with the field data obtained during the actual handling of coal at Mormugao Port Trust.

Ships Added Mass Effect on a Flexible Mooring Dolphin in Berthing Manoeuvre

This paper deals with the hydrodynamic effect of the ship on a flexible dolphin during a mooring manoeuvre. The hydrodynamic effect refers to the change in momentum of the surrounding fluid, which is defined by the concept of added mass. The main reason for the present study is to answer the question, “What is the effect of the added mass compared to the mass of the ship during the mooring procedure for a particular type of ship?” Measured angular frequencies of dolphin oscillations showed that the mathematical model can be approximated by the zero frequency limit. This simplifies the problem to some extent. The mooring is a pure rocking motion, and the 3D study is approximated by the strip theory approach. Moreover, the calculations were performed with conformal mapping using conformal Lewis mapping for the hull geometry. The fluid flow is assumed to be non-viscous, non-rotating and incompressible. The results showed that the additional mass effect must be taken into account when calculating the flexible dolphin loads.

Detection of Ships at Mooring Dolphins with Hidden Markov Models

IJpalen near the lock in IJmuiden are of great economic value to the Port of Amsterdam. These mooring dolphins have to endure a considerable amount of kinetic forces which can have an impact on the condition of the dolphins. These forces are created by either mooring or already moored ships. Any irregularities taking place at the IJpalen can have disastrous results unless timely addressed. The Port of Amsterdam has attached sensors to the poles and the plates, which measure changes in the dimensions regarding the dolphins. This report explores whether combining sensor data from the IJpalen and automatic identification system (AIS) data can produce beneficial insights into the dolphins’ states. We have used the sensor dataset to build a hidden Markov model (HMM) which predicts whether a ship is moored. We evaluated these results using the AIS data, in which can be discovered when a ship was moored at the IJpalen, producing remarkable results. We analyzed the sensor values using descriptive statistics to discover the normal and problem values. This research has obtained the following findings. First, descriptive statistics indicate a normal value range for the sensor values. Whenever a value out of this range is observed, it could be a problem case. Finally, it is possible to detect whether a ship is moored in the sensor data. An HMM on the z-angle of the plate of the east dolphin produces the best prediction, i.e., the highest accuracy of 90.2% according to the evaluation method, of a moored ship at the IJpalen.

Prototype testing for the partial removal and re-penetration of the mooring dolphin platform with multi-bucket foundations

The partial removal, adjusting, and re-penetrating tests were carried out on a mooring dolphin platform with three-bucket foundations after a seven-year service. When the bucket foundations were penetrated by internal and external pressure differential, the soil shear strength around the bucket skirt was different from that of the intact soil after installation. The side shear strength along the skirt may be increased with time due to the set-up effect. The shear strength factor α is an important time-varying factor to determine the skin friction of the foundation during installation and removal operations. The shear strength factors obtained by prototype records and theoretical methods in cohesive soils are compared, from total stress to effective stress methods. In addition, the prototype tests show that the foundations will be able to resist removal forces that are significantly larger than penetration forces due to the set-up effect after a long working time. The results show an 85% increase in the soil resistance after seven years for the three-bucket foundations with diameters of 6 m and penetration depths of 8.5 m. Meanwhile, the construction procedure and operation of the three-bucket foundations and the analysis of the extraction forces are also given for the partial removal. The test results support the successful removal by a reasonable overpressure without soil plug failure inside the buckets by controlling the pump discharge inside the buckets and reutilizing the structure with multi-bucket foundations after an initial service period of seven years.

Briefing: Maritime Structures – the design of challenging vertical pile dolphin solution

The demand for energy in Southeast Asia and the Pacific region has resulted in vast growth in gas exploration across the continent of Australia. With the approval for a number of liquefied natural gas (LNG) export facilities across the Australian seaboard, Arup Australasia has put its multi-disciplinary capabilities to full use in the delivery of a number of LNG jetties in Gladstone, Queensland in a design and construct collaboration with the contractor John Holland Group (JHG). This paper presents the design and construction of the dolphin structures, which were the result of close collaboration between JHG and Arup. The goal of this paper is to describe the importance of early constructability considerations and the complex interface between maritime, geotechnical and structural disciplines. The paper outlines the inputs and the consideration of both berthing and mooring dolphins designed to accommodate berthing and mooring of vessels of up to 220 000 m3 capacity. The approach of the paper is to describe the design solution in broad terms and selected key aspects in detail.

The Design of Mooring Dolphin Layout and Mooring Line Tension Analysis

Some marine industries choose to set up their activities in the coastal area northern part of Java Island, Indonesia, by considering the calmness of the Java Sea environment. A special terminal for liquid bulk cargo to transport fuel oil is being planned for construction in Sedayu Lawas village, Lamongan district, East Java Province. The ship carrying cargo oil require a pier and jetty in sufficient depth for loading and unloading. The jetty need to be enhanced to support more equipment for ship to port, which include breasting dolphin, mooring dolphin, trestle, and cause­way. In this respect a study is carried out to review the stress analysis of the mooring lines (ropes) attached to jetty for various mooring dolphin layout and arrangements. The metocean data such as wind and tides in the areas were processed and analyzed. The layout of the ship and mooring dolphin rope angle were designed in accordance with OCIMF code. The stress analysis of mooring rope for various layout mooring dolphin has been analyzed to determine whether the design layout is safe during operation. The rope stress were analyzed using time domain dynamic analysis for 10,800 seconds. The safety of ship during loading for various rope condition were presented. It is suggested that all ropes should be attached to mooring dolphin for ship and port safety.

Reliability Analysis of Piles in Multilayer Soil in Mooring Dolphin Structures

Reliability of complicated mooring dolphin structures (MDS) is estimated using few deterministic evaluations and an improved response surface method denoted as IRSM-second-order reliability method (SORM). It is a hybrid approach consisting of an IRSM, SORM, and several advanced factorial schemes. For this type of sophisticated analysis, simulation-based algorithm is impractical to implement. The concept is applied to estimate the risk of an existing MDS at the shore of Nile Delta. It is a large diameter steel-pile embedded in the sea bed. The Pile–Soil-System is represented by a nonlinear finite element model (NLFEM). In NLFEM, the steel pile is assumed to behave linearly under the considered working loads, but the soil is considered to behave nonlinearly. Moreover, the contact nonlinearity between the pile and the soil is taken into account. It is demonstrated that the reliability information on MDS can be extracted using tens of deterministic evaluations. It has been found that incorporation of the contact nonlinearity into analysis has no effect on the pile behavior. In the probabilistic analysis, the uncertainties in loading, material properties, and geometric details are taken into account. Both operational and structural limit states are considered. For the MDS considered in this study, it has been observed that the strength limit state (flexural) is more critical than the operational limit state (drift). The most important variables are the mooring loads, the radius and thickness of the pile, and the modulus of elasticity of steel.

Design and Construction Methods of Caisson-Type Maritime Infrastructures Using GFRP

AbstractGlass-fiber-reinforced polymers (GFRPs) are commonly used in various applications in civil-engineering projects. However, they are not common in the construction of civil-marine structures. The GFRP caisson technology was developed for the construction of two mooring dolphins in Puerto el Rosario (Fuerteventura, Spain). Ultraviolet-protected glass-fiber and epoxy resin coats were used to build a 12-m diameter, 13.3-m high cylindrical structure. A finite-element model was used to verify the sandwich composite configuration using the Tsai–Hill criteria—the shear strength of the skins and honeycomb core and the buckling and local failure modes with respect to the composite configuration. This is the first time that the two caissons were designed and built of polymeric materials and installed in a seaport. Accordingly, the construction technique marks a milestone in civil engineering because of its highly innovative nature in addition to significantly reducing the time associated with and the complexi...

Glass fiber-reinforced polymer caissons used for construction of mooring dolphins in Puerto del Rosario harbor (Fuerteventura, Canary Islands)

GFRP caisson technology was developed for construction of two mooring dolphins in Puerto del Rosario (Fuerteventura, Spain) in a more environmentally friendly way than traditional solutions. The construction technique marks a milestone in civil engineering because of its highly innovative nature that will significantly reduce time and complexity of construction operations. Glass fiber and gel-coated UV-protected epoxy resins were used to build a cylindrical structure of 12m diameter and 13.3m height, filled with granular aggregates and topped with a 2m concrete slab, where mooring bollards were fixed. GFRP caissons were manufactured in a factory in Jerez (Spain), transported by ship to the Canary Islands, assembled on site and launched into the sea with a light crane. The construction and environmental advantages include: savings of 75% in CO2 emissions and 90% reduction in the need for construction surfaces. Economically, the GFRP caisson solution was competitive compared to the original project solution.

An Improved Reliability Analysis Method for Mooring Dolphin Structures

A novel reliability evaluation procedure is proposed for analysis and design of offshore mooring dolphin structures (MDS). It is a hybrid approach consisting of an improved response surface method (IRSM), second-order reliability method (SORM), and several advanced factorial schemes. It is denoted as IRSM-SORM. Several schemes of IRSM-SORM are proposed and clarified with the help of an illustrative example.

Model tests on tilt adjustment techniques for a mooring dolphin platform with three suction caisson foundations in clay

A series of installation model tests have been performed in order to investigate the influence of the inclination angle on caisson installation penetration behavior during the suction-assisted penetration process and to explore the feasibility of the caisson tilt adjusting technique by applying suction/positive pressure and intermittent pumping among the caissons. The specially designed experimental model was a mooring dolphin platform with three suction caisson foundations. The test results indicate that the tilt angle could be adjusted to 0.5° by applying different suction pressures inside the caissons in soft clay during the suction-assisted penetration process, even with an initial tilt angle of up to 6.28°. Moreover, in stiff clay, it was still possible to adjust the tilt from 6.6° to 1.29°. Aside from applying the suction in the caissons, positive pressures were also applied to the caissons during the tilt adjustment at larger tilt angles. The reciprocating tilt adjustment process resulted in a larger soil heave, especially at larger tilt angles. This side effect would make the final insertion depth of the suction caisson less than the designed depth.

Penetration and Removal of the Mooring Dolphin Platform With Three Caisson Foundations

Mooring dolphin platforms (MDPs) with three caisson foundations were installed in the ice-drifting Bohai Sea of China. Before installation, prototype tests of penetration and removal processing were conducted near the design site. To determine the lateral soil pressure and skin friction of the caisson, soil pressure and strain gauge transducers were fixed along the external skirt of caisson B of MDP1. The shaft skin friction was calculated from the strain difference between any two points of the strain gauges. The transducer results indicated that when the soil property determined by unconsolidated and undrained (UU) triaxial tests was used to calculate the unit skin friction resistance, a value of the adhesion factor α of 1.5–2.0 is recommended. The factor α is 1–0.4 during the suction-assisted penetration phase. The lateral earth pressure coefficient K decreased with penetration depth, most likely due to seepage caused by underpressure. In addition, the difference between the measured values obtained from the soil pressure transducers represented the small tilt of MDP1 during the installation phase. The skin friction and lateral earth pressure significantly decreased in the removal phase, 12 h after the penetration phase, mainly due to the soil disturbance caused by suction penetration around the caisson.

Installation and Removal Records of Field Trials for Two Mooring Dolphin Platforms with Three Suction Caissons

In 1999, two mooring dolphin platforms (MDP1 and MDP2), each with three suction caissons, were installed in the JZ9–3 field of the Bohai Sea of China. Before installation, penetration and retrieval tests for MDP1 were conducted near the design location site. In 2006, after being in service for 7 years, partial removal and repenetration prototype trials were performed for MDP2. The MDP1 platform has the same geometric structure and weight as MDP2, in which each suction caisson is 6 m in diameter and 9 m in height. Typical soil profiles at the site mainly consist of organic silt, silty clay, and clay. Records from the transducers were relevant to the installation and retrieval of the suction caissons, which were performed by controlling the pump discharge into/out of the caissons. The results show that skin friction decreases because of the seepage effect that occurs after applying the suction pressure inside the caisson. However, clayey or silty soils with low permeability required more time and suction to create a seepage flow to lower resistance in the penetration or removal phases. The setup effect caused by suction significantly increases the skin friction resistance by 62–84%, and the pump-out pressure equals 1.79–2.04 times the pump-in suction after 7 years. The on-site data are valuable for further study on the design and construction of platforms with suction caissons, especially regarding external skin friction.

Behavior of a Pontoon Supported by a Mooring Dolphin in a Tsunami (First Report)

In recent years, a number of floating facilities for the utilization of ocean space, such as a marine disaster prevention base, floating restaurant, or floating container terminal, are planned, and some of them are actually built. Most of these facilities are of the pontoon-type floating structure, and the mooring system is basically a mooring dolphin. In the design of such facilities, it is important that the prediction of the motions of a pontoon-type floating body, supported by a mooring dolphin, in a tsunami is obtained. The objective of the present research is to develop a simulation system to obtain such predictions. In the present simulation system developed here, the three-dimensional (3D) MPS method (moving particle semi-implicit method) is used, and a solitary wave and borelike wave are applied to represent the incoming tsunami wave. The present paper is a report of the first stage of the research, and the heaving motion of the floating body acted upon by the tsunami is paid special attention, and we also report on the results of the study of the detaching of the floating body from the mooring dolphin.

Design Aspects of an LNG Loadout Jetty in Yemen

SummaryThis paper discusses the design problems associated with the site and how they were overcome in consultation with the construction contractor to best suit their expertise and equipment. The facility consists of an 800 m long approach trestle giving vehicular access to the loading platform and carrying the product pipelines, six mooring dolphins, four berthing dolphins, and a multi-level loading platform with four LNG loading arms. Conventional piled headstocks were chosen for the approach trestle, but deeper water along the berthing face led to jacket structures for each of the berthing and mooring dolphins, and the loading platform. The site geology generally consists of sandy sediments overlying Basaltic rock, with the depth of overburden varying from around 15 m at the berth to exposed rock onshore. Low tension capacity of driven piles required a significant number of tension anchors to be drilled into rock. The 7.8 m design wave at the site was a breaking wave over about one-third of the length of the trestle, and the headstock level was chosen to clear the wave crest by 1.5 m. The design of the topworks was being carried out by the main contractor at the same time, which resulted in uncertain pipe loads during the preliminary design phase. Prefabrication was carried out in Malaysia and transported to Yemen by barge, along with all equipment and construction materials. Provisions for sea transport of the fabricated jacket structures and the mechanics of their handling and installation were important parts of the design process.

The two mooring dolphin concept for exposed tanker terminals

The conventional design for a tanker terminal provides for two or more mooring dolphins on each side of the breasting dolphins. Head and stern lines are attached to the outer mooring dolphins and breast lines to the inner mooring dolphins. In exposed locations, the expense of construction may be significantly reduced if a way can be found to reduce the number of mooring dolphins required for the safe mooring of ships at a fixed berth. This paper, based on studies for a proposed terminal for tankers from 25,000 to 100,000 DWT in the Bay of Fundy in Eastern Canada, discusses the possibility of reducing the total number of mooring dolphins from four to two. Results of a static analysis of mooring loads due to wind and current and a hydraulic model test for mooring loads due to waves are presented. Operational aspects of the two mooring dolphin layout are discussed. It is concluded that the two mooring dolphin concept is an efficient mooring arrangement which will reduce the cost of fixed berth terminals. It is noted, however, that many of the smaller, older tankers in the world fleet do not have adequate mooring equipment to use such a berth and it is recommended that the necessary change in deck equipment be made to allow for such an arrangement. It is also recommended that ship personnel acquaint themselves with mooring procedures using breast and spring lines alone.