Cofferdam Construction Research Articles

Studi Kecepatan Aliran Air dengan Menggunakan Tabung Pitot

The tools and methods used in the measurement of water flow velocity are now very diverse, such as by using Venturi Meter, Orifice, Current Meter, Pitot Tube, and so forth. To learn more about water flow velocity measurement method, in order to improve professionalism in the field of water resources can be done research at Hydraulics Laboratory by researching Water Flow Analysis by Using Pitot Tubes. The research process will be carried out using three varied channel basis samples: reviewing the velocity of the water flow at the bottom of the channel with slippery base, reviewing the flow rate of the water on the gravel base channel, and reviewing the flow rate of the water on the channel with the decking concrete base. The expected result of this research is knowing the distribution of velocity in a cross section such as drainage channel, irrigation channel and river, so construction of water structure can be adjusted position placement in the open channel section. In addition it can be used as a reference in planning an open channel. One of the benefits to construction cofferdam construction speed distribution is to determine the dewatering system to be carried out during construction.Keywords— Flow Speed, Speed Distribution. Channel Basic Variations

Assessment of engineering geological design parameters for Kandil (CFRD) Dam, Kahramanmaras-Turkey

This paper discusses the engineering geological investigations, engineering properties of the rock mass at the dam site, and construction materials for the dam embankment. Kandil Dam is located in Kahramanmaras southeastern Turkey. It is used for energy production and water storage for irrigation. Engineering geological mapping, analysis of the discontinuity system, drilling, trial pitting, Lugeon water pressure tests and laboratory tests were undertaken. As a result of site survey and test results, three pervious and one impervious material quarries were identified. Rock mass classifications were performed in accordance with Rock Mass Rating (RMR) systems for the diversion tunnel. Bedrock in the foundation consists of amphibolites rated by the RMR method as “good rock”. Based on evaluation of the site and laboratory data, two different quarries were selected for embankment fill materials. In addition, one impervious material quarry was located for cofferdam construction.

The Research and Engineering Application of a New Hardfill Cofferdam in Shatuo Hydropower Station

A series of studies, including structure layout, detail design, material test, construction technology and prototype monitoring, etc are performed for the cofferdam on the left downstream bank of Shatuo hydropower station, which is situated on Wujiang River, Guizhou, China. Based on the research, the hardfill cofferdam with super-sized aggregates and ultralow cement in practical construction is firstly investigated. In which, the maximum aggregate size reaches 70cm and the minimum usage of cementing materials is 50 kg/m3 (25 kg/m3 for cement). According to the results of field detection and prototype monitoring, the implementation effect of the project is objectively evaluated. The research achievements and engineering practice can provide references for the design and construction of temporary cofferdam and low-medium permanent dam.

터널 굴착 및 가물막이 시공에 따른 주변 지하수계 유동분석

본 연구는 A호와 B호를 연결하는 도수로터널 굴착 및 가물막이 공사가 주변 지하수계에 미치는 영향을 정량적으로 평가하고자 수행하였으며, 이를 통해 인근 지하수 환경 변화 예측 및 터널의 라이닝 타설에 대한 효과를 검토하였다. 그 결과 터널 굴착 및 가물막이 공사기간 동안 터널 갱구부에서 최대 3.58 m의 지하수위 강하가 나타났으며, 터널 완공 및 라이닝 타설 시공 후 약 2년 경과 시점에서 자연상태 지하수위의 최대 90 %까지 회복하는 것으로 모사되었다. 터널 굴착에 따른 터널 내 지하수 유입량은 주향이동단층과 접하는 구간에서 터널의 배수설계기준을 초과하는 것으로 분석되었다. 이후 터널의 라이닝 타설이 완료된 후 지하수 유입량은 최대 <TEX>$0.006m^3/min/km$</TEX>로 감소하여, 라이닝 타설에 의한 효과는 93 % 이상으로 평가되었다. 또한 공사로 인한 인근 지역의 지하수 환경에 대한 분석 결과 민가, 사찰 및 견사 등에서 약 0.04~0.31 m의 수위강하가 발생하였으며, 이는 연구지역 인근에 위치한 국가지하수관측소의 연간 수위 변동량(1.3 m)의 24 %에 해당하는 수치로 분석되었다. This study is to quantitatively evaluate the impact on surrounding groundwater of waterway tunnel excavation and cofferdam construction in which A-dam and B-dam, so prediction of groundwater fluctuation and tunnel lining installation was studied. As a result, drawdown of groundwater level during tunnel excavation and cofferdam construction occurred about 3.58 m in the tunnel shaft. The initial condition of groundwater level recovered by up to 90 % was simulated after the completed the construction of the tunnel and lining installation. Groundwater inflow in the tunnel evaluated was analyzed to have exceeding water design criteria of the tunnel. The groundwater inflow is reduced to maximum <TEX>$0.006m^3/min/km$</TEX> after lining installation done in the tunnel, so effect of lining installation was evaluated as 93 % or more. Drawdown of about 0.04~0.31 m occurs in the houses and temples analysis of groundwater system of the surrounding area from construction. Drawdown has occurred nearly by considering annual groundwater level fluctuation of National Groundwater Observation Network.

Cofferdam Construction Monitoring of Haihe Bridge

The risk of steel sheet pile cofferdam construction is very high, and the collapse often results in heavy casualties. This paper discusses the calculation model of single wall steel sheet pile cofferdam system in detail during construction. Take for instance the R38# pier construction process of Haihe Bridge, the construction monitoring system of the steel sheet pile cofferdam is established to get the deformation and stress ofsteel sheet pile and supporting system. Comparative analysis between measurable results and 3D FEM results is done, and both are basically consistent.

댐 건설 기간 수위변화가 하반림 일대 습지 식생에 미치는 영향 -한탄강댐을 사례로-

This study was performed to monitor the effects of water level change on changes of landscape, vegetation community, and species diversity of riparian forest. Hantan river dam, study area, has been constructed in the area of Chansoo-myeon, Pocheon-si and Yeoncheon-eup, Yeoncheon-gun, Gyeonggi-do, which is a dam for flood control only in flooding season. Landscape changes were notable after the construction of coffer dam, and the changes were caused by water level increase in areas of riparian forests which consisted of mainly withered willow as a dominant species in the flooding season. It changed vegetation communities of riparian forest from Phragmites japonica and Salix koreensis to Phragmites japonica. Species diversity index was lowest in 2010 when the coffer dam was constructed and showed an increasing trend later. Thus, this study is well in agreement with a previous report that plants of the genus Salix wither by muddy water during flooding and also suggests, controlling water level of river and prediction of water level change's effects should be considered when any facilities are planned.

Floating Stability Analysis of Steel Boxed Cofferdam of Dongtinghu Long-Span Bridge

With the development of highway and railway, the construction technique of bridge is developing at a lighting speed. Because of the need to across the river and channel, which span getting more and more large, the foundation of the bridge piers should be more and more stable. Lead to raising the load capacity of the pier foundation. The technique cofferdam construction is an effective mean to solve large foundation problems in deep water. And comparing the empirical value to the simulating value, the results demonstrate FLUENT is a reliable program to simulate the water resistance. This paper gives a model for complete resistance calculation and stability analysis of floating steel cofferdam which will provide a template for similar analysis of engineering application.

Research of Hydraulic Characteristics of Cofferdam and Leaching System on Joint Way of Nanjing Second Yangtse Bridge

The hydraulic filling is the construction method of joint way in Nanjing Second Yangze Bridge. The leaching facility, drainage time and cofferdam stability in filling are key points in design. By laboratory test, the compaction, direct shear and permeability test of different compaction are investigated. The deformation through field monitor is carried during the cofferdam construction and hydraulic filling. After parameter test and stability analysis according to hydraulic filling, it is shown that the drainage ditch in base of cofferdam can satisfy drainage requirement, the leaching time is about half of one month. The compactness of cofferdam is 0.92. The slope of cofferdam during construction and hydraulic filling is in stability by analysis. And the cofferdam is in stable situation during hydraulic filling according to deformation monitoring result.

Slope Stability Analysis of High Rockfill Cofferdam Considered with its Construction and Working Processing

Slope stability of high rockfill cofferdam is related not only to the structure and shape, material characterization, working characteristics of the cofferdam body, but also to the construction process. The influences of rock mechanics parameters are analyzed, which caused by the changes of structural stress state and transfusion equivalent stress in cofferdam construction process. Based on the slope stability strength reduction method, the slope stability analysis model of high rockfill cofferdam mirroring the construction process is established. At the same time, the parameter calculation methods are submitted and the correctness is proved. By the slope stability analysis of construction-running process, the results show that the most dangerous condition of cofferdam slope appears in the period of water level falling after pit excavation finished. With the increase of level falling speed, the position of the cofferdam dangerous sliding surface shifted from downstream slope to upstream slope. When the front weir level falling speed is determinate, the slope safety factor is appearing downward trend firstly and then upward trend, the minimum slope safety factor and the critical time is related with the level felling speed.

Double-Wall Cofferdam of Hero Bridge Calculation

Hero Bridge is an extraordinarily huge bride across northern branch Ganjiang River, in the city of Nanchang. Main tower adopted single column slanted pylon space twist face back cable structure. Its construction is based on double-wall cofferdam method. The paper discuss thecalculation of key step and key position for the key technology in terms of double-wall cofferdam and platform underwater construction, Which include the design of the base construction and double-wall cofferdam,steel cofferdam construction, the calculation and checking of the cofferdam and so on.

Calculation of Hongdu Bridge Foundation Construction

Hongdu Bridge is an extraordinarily huge bride across northern branch Ganjiang River, in the city of Nanchang. Main tower adopted single column slanted pylon space twist face back cable structure. Its construction is based on double-wall cofferdam method. The paper discuss thecalculation of key step and key position for the key technology in terms of double-wall cofferdam and platform underwater construction, Which include the design of the base construction and double-wall cofferdam,steel cofferdam construction, the calculation and checking of the cofferdam and so on. The whole length of 9.5 km, except the starting period of about 2.4 km for roadbed type, the other sections of approximately 7 km. The project always invests about 18 Billion yuan.

Selecting Flow Frequency Distributions for Designing a Small Low-Head Dam Removal Cofferdam

One of the first steps in removing a dam is the construction of a cofferdam so that demolition activities can proceed safely. The time necessary for removing a small low-head dam is often on the order of a few months. To minimize the cofferdam construction cost, these dams are generally removed during the low flow months of the year. Therefore, design of cofferdams should be based on river flow series during the dam removal period, rather than the entire year. In this study, available hourly and daily average records at the recently removed Marmot Dam on the Sandy River, Oregon are analyzed for four dam removal periods, varying from 1 to 4 months (July through October). L-moment ratio diagrams and probability plot correlation coefficients are used to select log-Pearson Type 3 and two- and three-parameter lognormal probability distribution functions for representing at-site maximum flow series. From a hydrologic engineering consideration, the analysis suggests an optimal dam removal period of 3 months (July through September). An estimate of flow on the basis of annual maximum series is an order of magnitude higher, which would result in an uneconomical design of the cofferdam.

Underwater Fiber–Reinforced Polymers Repair of Prestressed Piles in the Allen Creek Bridge

This paper presents an overview of a demonstration project in which corroding prestressed piles located in tidal waters were wrapped underwater using carbon and glass fiber-reinforced polymer material. An innovative instrumentation scheme was developed to allow assessment of the prewrap and postwrap corrosion state using linear polarization. This system is simple to install and eliminates the need for wiring or junction boxes. The underwater wrap used a unique water-activated urethane resin system that eliminated the need for cofferdam construction. Linear polarization measurements taken before and after wrapping indicate that the corrosion rate in the wrapped specimens is consistently lower than those in its unwrapped counterpart. These preliminary findings are encouraging and suggest that underwater wrapping without cofferdam construction may provide a cost-effective solution for pile repair.

Boat Bridge, Canary Wharf, London, UK

In 2001, the need for a temporary bridge in Canary Wharf, London, UK was identified to serve the construction of a 32-storey building on an 'island' site. The island was formed by a filled twin cell steel sheet piled cofferdam wall. The bridge had to allow the passage of general marine craft with a clear opening of 15m. It had to serve the construction site for 3 years and take full highway loading, with an allowance for abnormal loading. A two-lane carriageway of 7.3m width with full parapet protection and a pedestrian access route were specified. The cofferdam construction meant that only modest abutment loads could be imposed. The design solution was a simply supported beam steel deck structure. To move the bridge, it was designed to be lifted off its bearings with the weight transferred to pontoons, and then sailed out of the channel and moored until the barge had passed, before reversing the process. Details are given of the deck structure, abutments, hinge and bearings, bridge lifting process, bridge flotation, and bow thrusters for moving the pontoons.

Project-Specific Steel Sheet Piling Applications

Hot-rolled, heavy-gauge steel sheet piling has advantages over other available products including concrete, vinyl, and fiberglass-reinforced polymers for bulkhead and deep-excavation applications. For FEMA seawall bulkheads, steel sheet piling provides the only practical structural solution available. For deep excavations, steel sheet piling typically provides the most economical solution for the conditions encountered in braced trench and cofferdam construction. A steel sheet pile wall consists of a continuous row of interlock- ing vertical segments that form essentially a straight wall that is capable of acting integrally. There are two primary types of steel sheet pile wall structures: cantilevered and anchored. Walers are commonly used in conjunction with tiebacks to construct anchored sheet pile walls. Tiebacks are typically installed as either ground anchors or anchor rods secured to deadmen. Cofferdams are a special form of steel sheet pile construction in which the method of resistance to soil forces is provided through the ability of the circular footprint to function either as a compression or tension ring. The design of sheet pile walls involves the evaluation of loads imposed by soil, water, surcharging, and other externally applied forces. The analysis of a sheet pile wall includes a determination of the required depth of embedment, sizing of any anchorage systems, and verification that the actual flexural stresses do not exceed the allowable. Safety factors are typically included in the determination of the minimum embedment depth.

Unique cofferdam construction: Pt Marion Lock and Dam, Pennsylvania : D. A. Bruce, B. Greene & A. Schaffer, Ground Engineering, 29(3), 1996, pp 41–44

Unique cofferdam construction: Pt Marion Lock and Dam, Pennsylvania : D. A. Bruce, B. Greene & A. Schaffer, Ground Engineering, 29(3), 1996, pp 41–44

Design and construction of North America's largest unbraced cofferdam

In Boston, Massachusetts (U.S.A.), a new immersed tube tunnel has recently been built. Adjacent to this tunnel, a subsurface ventilation building is planned. To allow construction of this ventilation building, a temporary cofferdam has been designed and built. The paper describes this cofferdam, the many load cases, the effects of the different soil layers, and its construction method.

Characteristics of Newspaper Articles on the Disputes of Nagara Coffer-Dam Construction

Characteristics of Newspaper Articles on the Disputes of Nagara Coffer-Dam Construction

Ground Stabilization for foundation and excavation construction in Florida karst topography

The construction of additional facilities at the Florida Power Corporation's Crystal River Energy Complex required an extensive stabilization program to construct foundations for approximately one half mile of cooling towers. This paper presents an overview of the techniques and methods used in the construction of additional facilities at the Crystal River Generating Station. Excavations for intake and discharge structures were to be more than 20 ft below the water table. Cooling tower foundations were constructed on extensively solutioned Florida limerock located on the central Gulf Coast of Florida. Hybrid ground modification techniques were used to stabilize soft or loose soils and solution features in the underlying limerock, allowing mat and spread footing foundations to be used for most of the facility. The ground modification techniques were used to detect, collapse, densify, and fill solution features below the structure foundations. The bearing capacity after ground modification was verified by field load tests. Subsurface investigations indicated that sheet pile excavations with grouted seals were the optimal technique for cofferdam excavations in the limerock formation. Existing collapsed caverns were encountered during construction of the cofferdam for the intake structure and the adjacent discharge structure, requiring a fast-track design change, considerable field coordination, and daily modifications to accommodate the varied conditions encountered. Tied-back soldier pile cofferdam construction was combined with grouting, underwater excavation, and a massive, unreinforced, concrete tremie slab with grouted anchors, and installed off a barge to provide a dewatered excavation. This project involved the use of hybrid soil-rock anchors to anchor one of the largest continuous placement tremie seals installed in Florida. Other excavations used sheeting and grouting of the underlying limerock formation to provide a dewatered excavation. Ground modification techniques were used to treat a filled cavern discovered in the corner of one discharge structure. The entire construction of this facility was confined to a narrow work area by existing wetlands and the generating station discharge canal. Strict environmental restrictions required by the regulatory agencies to prevent impacts to the surrounding area were imposed on this project.

KESSOCK BRIDGE: CONSTRUCTION.

Keywords CLEVELAND BRIDGE & ENGINEERING, REDPATH DORMAN LONG BRIDGES, CONSTRUCTION, BUILDING, SUBSTRUCTURES, PROBLEMS, COFFERDAMS, ERECTION, SUPERSTRUCTURES, TEMPORARY, WORKS, SYSTEMS, PIERS, APPROACHES, FABRICATION, CONTROL, DIMENSIONAL, SITES, WELDING, PYLONS, CABLES, STAYS, RESTRAINT, LONGITUDINAL, CLOSURES, LABOUR, ACCURACY, PROFILES, DECKS, SURFACING, FURNITURE, PILES, CABLE STAYED KESSOCK, BEAULY FIRTH, SCOTLAND UK... Show All