Scour Countermeasures Using Geosynthetics and Partially Grouted Riprap

2000 ◽  
Vol 1696 (1) ◽  
pp. 244-250 ◽  
Author(s):  
Michael H. Heibaum
Keyword(s):  
Layer Thickness ◽  
Special Equipment ◽  
Protection Measure ◽  
Filter Placement ◽  
Main Requirement ◽  
Excess Water ◽  
Scour Protection ◽  
Nonwoven Geotextile ◽  
Geotextile Filter ◽  
Scour Countermeasure

The main requirement of any scour countermeasure or scour protection measure is to prevent erosion, so a top layer has to be built that is sufficiently resistant against the hydrodynamic loads and that protects the subsoil. Single elements have to be large enough to withstand the scouring forces and require an appropriate layer thickness. Smaller, mutually connected elements allow for a moderate layer thickness but provide the same resistance. To avoid excess water pressures below the top layer, permeable systems are recommended. A very reliable system is partially grouted riprap, which meets all the requirements of strength, flexibility, and permeability. Permeable systems need a well-designed filter. Placement of a grain filter or a geotextile filter is complicated by the current, so special equipment is needed. In mild currents a “sandmat” (a sand-filled nonwoven geotextile) can be used. In stronger currents use of geosynthetic geocontainers is proposed to achieve both a high resistance against the current and a well-performing filter.

scholarly journals PHYSICAL MODELING STUDY ON SCOUR AND SCOUR COUNTERMEASURE FOR SEA-CROSSING BRIDGE PIERS

2012 ◽  
Vol 1 (33) ◽  
pp. 83
Author(s):  
Hsin Hung Chen ◽  
Ray-Yeng Yang ◽  
Ping-Chiao Kuo ◽  
Hwung-Hweng Hwung
Keyword(s):  
Physical Model ◽  
Model Tests ◽  
Bridge Piers ◽  
Test Series ◽  
Model Study ◽  
Sea Bed ◽  
Wave Basin ◽  
Scour Protection ◽  
Hydraulics Laboratory ◽  
Scour Countermeasure

There are significant engineering challenges in placing the sea-crossing bridge piers in more or les shallow coastal waters because, as well as having to withstand storm-force waves and tidal currents, the bridge piers have to remain stable on a sea bed that may be continuously changing. One of the major challenges faced by designers is how to predict, and prevent, scour of the seabed sediments around the sea-crossing bridge piers. This paper describes a physical model study on scour and scour countermeasure for sea-crossing bridge piers. A 1:49 scale movable bed model tests were carried out in the Near-shore Wave Basin (NSWB, 27m x 19m) at the Tainan Hydraulics Laboratory, National Chang Kung University (NCKU), Tainan, Taiwan, with the sea-crossing bridge piers in the test area. Three series of physical model tests were performed in this study. The aim of the first test series is to investigate the maximum scour depth for the initial construction of bridge piers with only one pier model. Then the second test series were conducted to investigate the greatest magnitude of local scour and potential scour area in the sand bed around the sea-crossing bridge group piers with no scour protection. Based on the analysis from the former NSWB experimental results, the suitable scour countermeasure for sea-crossing bridge piers would be proposed and validated its function of preventing scour in the third test series.

Studies on the effect of an upstream pier as a scour protection measure of a downstream bridge pier

2014 ◽  
pp. 2047-2052 ◽  
Author(s):  
Shiva Khaple ◽  
Prashanth Hanmaiahgari ◽  
Subhasish Dey
Keyword(s):  
Bridge Pier ◽  
Protection Measure ◽  
Scour Protection

scholarly journals Effect of the Number of Constrictions on the Filtration Behaviour of a Soil-Geotextile System

2020 ◽  
Vol 28 (1(139)) ◽  
pp. 87-92
Author(s):  
Anna Miszkowska ◽  
Anna Miszkowska ◽  
Eugeniusz Koda ◽  
Zygmunt Krzywosz
Keyword(s):  
Selection Criteria ◽  
Fine Particles ◽  
Filter Design ◽  
Ratio Test ◽  
Flow Through ◽  
Gradient Ratio ◽  
Geotextile Filters ◽  
Nonwoven Geotextile ◽  
Geotextile Filter ◽  
Base Soil

Nonwoven geotextile filters have been used in geo-environmental engineering for decades to prevent the movement of base soil fine particles, allowing adequate seepage to flow through the geotextile plane. Most of the design criteria developed for nonwoven geotextiles are based only on the comparison between their characteristic opening size and the indicative diameter of the soil to be filtered. In the meantime, the nonwoven geotextile fibrous structure has an influence on the filtration of the soil-geotextile system. In this paper the numbers of constrictions of nonwoven geotextile samples were determined to verify the existence of a correlation between the geotextile structure and the filtration behaviour of soil-geotextile systems. The compatibility between an internally unstable soil and a nonwoven geotextile filter was evaluated using the gradient ratio test. The results obtained can also be the basis for modifying the geotextile filter design and selection criteria.

Feasibility of a Dynamically Stable Rock Armour Layer Scour Protection for Offshore Wind Farms

2014 ◽  
Author(s):  
Philippe de Schoesitter ◽  
Sarah Audenaert ◽  
Leen Baelus ◽  
Annelies Bolle ◽  
Andrew Brown ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Wind Farms ◽  
Filter Material ◽  
Visual Observation ◽  
Offshore Wind ◽  
Test Series ◽  
Offshore Wind Turbine ◽  
Stone Size ◽  
Physical Test ◽  
Scour Protection

Armour layer scour protections around offshore wind turbine foundations are commonly designed to provide a static protection in storm conditions, which means no or limited movement of rock is allowed (Den Boon et al., 2004, De Vos et al., 2011). This approach often results in large stone sizes and high scour protection costs. Therefore, a dynamic approach can be an interesting alternative. Such a dynamic design can be achieved by decreasing the armour stone size allowing movement of the stones and increasing the armour layer thickness to prevent filter layer exposure. A physical test program was conducted to investigate the feasibility and behaviour of such a dynamically stable scour protection. In this model, a monopile foundation exposed to typical North Sea combinations of unidirectional currents and waves was reproduced in a wave flume. The program included a number of test series each with different water depths. In each test series, the armour layer stone size and the armour layer thickness were varied, in order to obtain a reshaping scour protection, without filter material exposure. Damage and failure were assessed both visually and using a 3D-laser profiler. Because previous works on damage numbers of rock armour layer scour protections mainly focus on static design, a new damage number was introduced and compared to the visual observation. This allowed the definition of a ‘dynamic area’ between static design and failure. Scour pit development in time and equilibrium profiling were also analyzed. The results of the tests showed that the concept of a dynamically stable scour protection is feasible.

Effect of filter–separators on the clogging of leachate collection systems

2006 ◽  
Vol 43 (7) ◽  
pp. 674-693 ◽  
Author(s):  
Reagan McIsaac ◽  
R Kerry Rowe
Keyword(s):  
Hydraulic Conductivity ◽  
Thick Layer ◽  
Sand Layer ◽  
Drainage Layer ◽  
Granular Filter ◽  
Leachate Collection ◽  
Mesocosm Experiments ◽  
Nonwoven Geotextile ◽  
Geotextile Filter ◽  
Waste Leachate

This paper reports the results obtained after 6 years operation of nine mesocosm experiments that simulate the 50 cm of the drainage layer closest to the leachate collection pipe in a landfill. Five different design configurations were examined involving a 300 mm thick layer of coarse (38 mm) gravel. The designs differed in terms of the presence, nature, and location of a filter–separator layer either at the waste–gravel interface or partway through the gravel. A nonwoven geotextile filter–separator (GTF/S) is shown to reduce clogging of the gravel relative to the no filter–separator or woven GTF/S designs. Some clogging of the geotextiles is reported, with reductions in geotextile hydraulic conductivity of 23% for the woven GTF/S, 74%–89% for the nonwoven GTF/S, and 75%–94% for the nonwoven geotextile partway through the gravel. The clogged nonwoven geotextile filter–separator maintained a higher hydraulic conductivity than the extracted woven geotextile. Of the designs with a filter–separator between the waste and gravel, the granular filter–separator most effectively reduced clogging of the gravel but at the expense of leachate mounding above the sand once the sand layer clogs. The design with a nonwoven geotextile partway through the gravel (GTMF) provides better protection of the underlying gravel from clogging than other designs involving a geotextile.Key words: landfill, waste, leachate, clogging, biofilm, geotextile.

Tailings-nonwoven geotextile filter compatibility in mining applications

2010 ◽  
Vol 28 (2) ◽  
pp. 136-148 ◽  
Author(s):  
Ennio M. Palmeira ◽  
Elder A. Beirigo ◽  
Maria G. Gardoni
Keyword(s):  
Nonwoven Geotextile ◽  
Geotextile Filter

scholarly journals Optimization of Process Parameters for Additively Produced Tool Steel 1.2709 with a Layer Thickness of 100 μm

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2852
Author(s):  
Vladislav Andronov ◽  
Jan Šimota ◽  
Libor Beránek ◽  
Jiří Blažek ◽  
Filip Rušar
Keyword(s):  
3D Printing ◽  
Layer Thickness ◽  
Tool Steel ◽  
Process Parameters ◽  
Subsequent Development ◽  
Main Requirement ◽  
Optimization Of Process Parameters ◽  
Study Methodology ◽  
Pressure Die Casting ◽  
Printing Parameters

The purpose of this study was to find and optimize the process parameters of producing tool steel 1.2709 at a layer thickness of 100 μm by DMLS (Direct Metal Laser Sintering). HPDC (High Pressure Die Casting) tools are printed from this material. To date, only layer thicknesses of 20–50 μm are used, and parameters for 100 µm were an undescribed area, according to the state of the art. Increasing the layer thickness could lead to time reduction and higher economic efficiency. The study methodology was divided into several steps. The first step was the research of the single-track 3D printing parameters for the subsequent development of a more accurate description of process parameters. Then, in the second step, volume samples were produced in two campaigns, whose porosity was evaluated by metallographic and CT (computed tomography) analysis. The main requirement for the process parameters was a relative density of the printed material of at least 99.9%, which was achieved and confirmed using the parameters for the production of the samples for the tensile test. Therefore, the results of this article could serve as a methodological procedure for optimizing the parameters to streamline the 3D printing process, and the developed parameters may be used for the productive and quality 3D printing of 1.2709 tool steel.

Effects of compression during formation on the microstructure of composite hydroxylapatite/plaster implants for bone reconstruction

1988 ◽  
Vol 46 ◽  
pp. 750-751
Author(s):  
J. Hanker ◽  
K. Cowden ◽  
R. Noecker ◽  
P. Yates ◽  
N. Georgiade ◽  
...  
Keyword(s):  
Cosmetic Surgery ◽  
Glass Plate ◽  
Surgical Reconstruction ◽  
Equal Weight ◽  
Sintered Ceramic ◽  
Setting Times ◽  
Excess Water ◽  
Mixture Prior ◽  
Mechanical Strengths ◽  
Calcium Sulfate Hemihydrate

Composites of plaster of Paris (PP) and hydroxylapatite (HA) particles are being applied for the surgical reconstruction of craniofacial bone defects and for cosmetic surgery. Two types of HA particles are being employed, the dense sintered ceramic (DHA) and the porous, coralline hydroxylapatite (PHA) particles. Excess water is expressed out of the moistened HA/PP mixture prior to implantation and setting by pressing it in a non-tapered syringe against a glass plate. This results in implants with faster setting times and greater mechanical strengths. It was therefore of interest to compare samples of the compressed versus noncompressed mixtures to see whether or not any changes in their microstructure after setting could be related to these different properties.USG Medical Grade Calcium Sulfate Hemihydrate (which has the lowest mortar consistency of any known plaster) was mixed with an equal weight of Interpore 200 particles (a commercial form of PHA). After moistening with a minimum amount of water, disc-shaped noncompressed samples were made by filling small holes (0.339 in. diameter x 0.053 in. deep) in polypropylene molds with a microspatula.

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