Development of Steel Sheet Piling

Metal sheet piling was a natural advancement in the evolution of this product as we entered the “Iron Age” in the mid-1800’s. Cast iron was used to make some crude sections, but these were not successful due to lack of ductility. Toward the end of the century, Bessemer steel was developed and mills began hot-rolling I-beams, channels and angles, among other structural shapes. Freistadt-type piling appeared about 1890, fabricated from a rolled channel section as shown in Figure 1. Z-bars riveted to the web provided a groove into which the flange of a channel could slide, thus forming a crude but innovative interlock. A “Universal” type sheet piling introduced in Great Britain about 1895 utilized hot-rolled I-beams and special clips to join the flanges of the I-beams together. The efficiency of this wall was low because the I-beams were aligned in the weak structural direction.

Don C. Warrington
Figure 1: Freistadt Sheet Piling

LARSSEN SHAPES

Inventors were striving to develop a sheet piling that would contain interlocks rolled into the beam during the manufacturing process, rather than attached afterwards by riveting. Gregson (USA) patented a bulb and jaw interlock in 1899, however this still resulted in production of a flat section with relatively small section modulus. Trygve Larssen obtained a German patent in 1904 for a deep, hot rolled section that greatly increased the strength and efficiency of steel walls and represented a major advancement. Larssen’s piling wall assumed a “wave shape” when assembled and all subsequent developments for efficient sheet pile walls are based on this concept. Larssen’s section still contained a partially fabricated interlock and it was not until 1914, that a rivetless Larssen interlock appeared in Germany.

Figure 3
Figure 2: Historical Sheet Pile Sections

In the United States, Lackawanna Steel Co. (later acquired by Bethlehem Steel Corp.) was a flat sheet piling shape and several arched types with rolled, integral interlocks as early as 1910.Carnegie Steel Co. (U.S. Steel Corp.) offered three flat sections with rolled-on interlocks and one fabricated section. By 1929, Carnegie’s catalogue illustrated four deep-arch, two shallow-arch and two straight sections. Some of these and other historical sections of sheet piling are showing Figure 2.

Z-TYPE SHAPES

Z-shaped piles followed the Larssen concept for a wave-shaped profile but with the added advantage that the interlocks are formed on the outer elements of the section. The extra metalis put to best use, since it is well out from the neutral axis of the wall. Larssen interlocks are located on the neutral axis. Surprisingly, Z-shaped piles were produced in Europe as early as 1911. The Ransome profile looked very much like some of today’s lightweight Z-shapes. The deeper Lamp Z-pile introduced about 1913, resembles a modern ball and socket Z-type pile.

In Europe, Z-type shapes fell from favour when the Larssen U-types were developed. Two Z-shapes were introduced in the United States in the 1930’s and became quite popular. PZ-38 and PZ-32 offered wider and deeper sections than any of the arch shaped shapes then available. Z-shaped piles obtained some impetus in the U.S. from the long-standing controversy regarding the actual moment-resisting properties of U and Arch shaped sections.

Figure 4
Figure 3: Typical Hot-Rolled Steel Sheet Piling

Z-shaped piles interlock on the wall extremities and provide a solid web connecting the two flanges. When the PZ-27 section was introduced in the 1940’s, its section modulus of 30.2 in3/ft was almost three times that published for the arch section with the identical weight per square foot of wall. This section subsequently became the all-time most popular sheet piling section in history. Z-type shapes are now produced with section modulii ranging from 8.6 to about 85 in3/foot of wall.

The Z-type piling is predominantly used in retaining and floodwall applications where bending strength governs the design and no deflection (swing) between sheets is required. Most producers do not guarantee any swing although some can generally be attained or area can be built by providing some bent pieces in the run. Turns in the wall alignment can be made with standard bent or fabricated corners. Typical configurations are shown in Figure 3.

Z-piles are not used in applications when interlock strength is required such as filled cells. These sheets would tend to stretch and flatten in these cases. No minimum interlock strength is offered for this reason. When interlock tension is the primary consideration for design, an arched or straight web piling should be used.

STRAIGHT WEB SECTIONS

Flat profile sections were originally produced only because of mill rolling limitations. Competition and customer demand prompted the expansion into structurally efficient sheet piling. It was discovered that these flat profiles had strength in tension that was advantageous for building circular, filled structures from sheet piling. About 1908 a large cellular cofferdam was built on the Black Rock River in Buffalo N.Y. in order to de-water the site for a new lock. This conceptwas progressively expanded to include circular and diaphragm-shaped cells for piers and breakwaters that might have formerly been built of timber cribs or masonry.

The use of large diameter, cellular cofferdams was given a special impetus in the 1930’s when the Tennessee Valley Authority began a series of hydro dams and navigation locks on that river system in the south-eastern United States. Not only did TVA engineers develop new design methods for designing these large structures, they developed better ways of installing and maintaining them.

Flat sheets have little strength to resist bending, but do have very strong interlocks to resist “hoop” stress. These piles are used almost exclusively for building large, filled cellular structures. Flat sheets must provide some ability to “swing” between sheets so that a circle can be closed. Most manufacturers will guarantee a minimum swing of 8 to 10 degrees between adjacent sheets for standard lengths of piling. For overly long pieces, these warranties must generally be negotiated.

Available interlock strengths must be known in advance in order to design a structure that will be safe against bursting. Most manufacturers will guarantee a “minimum” interlock strength based on tension tests conducted on a number of representative production samples. It has been determined from experience that interlock dimensional tolerances that fall within certain limitations will provide tension values characteristic of the entire production run. Flat sheet piling is available only as a hot rolled product, since the cold-finishing process does not provide an interlock with sufficient strength in tension. Interlock strengths have been gradually increased due to the demand to build larger cells for deeper cofferdams.

Most flat sheet piling has been used to construct temporary cellular cofferdams. After the initial use, the sheets are pulled and used in other portions of the project or perhaps sold for another project elsewhere. Other flat sheets are used in permanent structures such as breakwaters, earth containment sites, piers and other applications.

COLD FINISHED PILING

Since the early 1970’s another method of producing steel sheet piling has greatly expanded the availability and the selection of sections. This new method uses hot-rolled sheets in coil form, fed through a series of cold-rolling stands to form “Z” or “arch” shapes complete with a simple, hook-type interlock. This involves a relatively inexpensive capital expenditure compared to the hot-rolled product and has attracted a number of new producers.These steel pilings are shallow-depth sections, cold formed to a constant thick-ness of less than 0.25 inch and manufactured in accordance with ASTM A 857. Yield strength is dependent on the gauge thickness and varies between 25 and 36 kips per square inch (ksi). These sections have low-section moduli and very low moments of inertia in comparison to heavy-gauge Z-sections. Specialized coatings such as hot dip galvanized, zinc plated, and aluminized steel are available for improved corrosion resistance. Light-gauge piling should be considered for temporary or minor structures. Light-gauge piling can be considered for permanent construction when accompanied by a detailed corrosion investigation. Field tests should minimally include pH and resistivity measurements.

Figure 5
Figure 4: Typical Cold-Rolled Sheet Piling Sections

See Figure 4 for typical light-gauge sections.

HIGH MODULUS SECTIONS

There is a limited but regular demand for sheet piling with strength properties that exceed those available from standard products. These may be required for deep excavations, poor soil conditions, deeper dredge lines and other special conditions.

SHEET PILING NOMENCLATURE & IDENTIFICATION

U.S. producers of sheet piling standardized the identification of sheet piling sections so they could be specified without reference to a particular manufacturers product. The identification included a “P” (piling”) “Z” (type or shape) and “27” the weight, or PZ-27. Arch and flat shapes were similarly described. Non-U.S. and cold-finishing producers have their own “in house” identification systems. There is now no universal nomenclature system. It is common practice recently to specify the bending moment to be satisfied which then allows the contractor considerable flexibility in his selection of a section and a supplier. This bending moment specification should not be used blindly, however, as many sheet pile designs (especially those using vinyl or pultruded fibreglass sheeting) are principally governed by deflection.

ORDERING SHEET PILING

Like other steel products, steel sheet piling may be ordered by reference to a standard specification. In the United States this standard is published by the American Society of Testing Materials (ASTM) 1916 Race Street, Philadelphia, PA 19103-1187. The basic ASTM Specification A-328 and others listed may be obtained by writing to the Society or visiting their website//www.astm.org.

This specification covers the steel making process, the chemistry requirements, the minimum yield and ultimate strength. Delivery is referenced in ASTM Specification A-6. The ASTM Specification does not cover interlock tolerances, straightness, interlock strength, nor does it cover rental or second hand material. These are between buyer and seller.

Other Specifications include:

  • Canadian Specification CSA 44 W, CAST 44W/70
  • British Specification BS4360 – Various Grades
  • European Specification: ST SP 37; ST SP 45; ST SP 5.

STEEL SHEET PILING TODAY

While the annual consumption of sheet piling in this country rarely exceeds 250,000 U.S. tons, the number of producers and the availability of sections has increased dramatically in the last ten years. In 1960 there were two U.S. producers, each offering nine sheet piling sections. Today there are at least 14 U.S. and non-U.S. producers offering over 200 sections in this country. Competitive factors have generated development of new, wider, more-efficient sections. Large Z-shapes are now available for deep construction with section modulus of almost twice that previously available. A wall system has been developed using large H-sections combined with light Z-shapes that greatly increases the section modulus. Light weight “gauge” material is produced on the cold forming mills for economical shallow bulkheading and trench work.

Higher strength steels up to 60 ksi yield point have also been effectively used in sheet piling design. These grades offer the opportunity to save weight or to extend bending or interlock strengths beyond those of conventional grades. For those applications that require it, corrosion resistant steel can also be specified as well.

(This article comes from pilebuckinternational.com editor released)

Z Type Steel Sheet Pile

Introduction:

Z-type steel sheet pile lock on both sides of the neutral axis symmetric distribution, and the continuity of the web, made of steel sheet pile cross section modulus is improved to a great extent, so as to ensure the mechanical properties of the cross section are fully exerted.

Features:
(1) The cross section width, pile driving effect is remarkable.
(2) The section modulus.
(3) The moment of inertia is higher, to enhance the stiffness of the steel sheet pile wall, reduce the deformation of the structure.
(4) Good corrosion resistant effect.

Advantages:
(1) design flexible, have relatively high section modulus and quality;
(2) a higher moment of inertia, so as to increase the stiffness of sheet pile wall, reduce the displacement deformation;
(3) large width, save the hoisting and driving time effectively;
(4) section width increase, decrease the amount of reducing the sheet pile wall, directly improve the performance of the water;
(5) In the severe corrosion of the thickening process, more excellent corrosion resistance.

(This article comes from Alibaba.com editor released)

Method for Hot Rolling Z-Sections Sheet Piles

BACKGROUND ART

Steel sheet piles are long structural sections provided with an interlocking system that allows building continuous retaining walls. The most common sheet pile sections are: Z-sections, U-sections, Ω-sections, flat-web sections and H or double-T sections.

Z-section sheet piles include a first flange, a second flange, which is substantially parallel to the first flange, an inclined web, a first corner joining the web to the first flange, a second corner joining the web to the second flange, wherein each of the corners has an opening angle α greater than 90°, preferably in the range of 110° to 140°. The longitudinal edges of the flanges are generally equipped with coupling means for interlocking purposes. In distinct contrast to other sheet pile sections, Z-section sheet piles do not have a plane of symmetry.

It is well known in the art to produce Z-section sheet piles by a hot rolling process, starting from slabs or, more recently, from beam blanks.

U.S. Pat. No. 5,671,630 discloses a method for rolling such Z-section sheet piles from a beam blank. According to this method, a preform of the sheet pile is rolled with curved preforms of the web and the flanges. The curved preform of the web comprises: two web/flange transition sections, which are substantially flat sections parallel to the rolling plane; a middle section, which is a substantially flat section defining an angle of about 60° with the rolling plane; and two connecting bows, connecting the web/flange transition sections to the oblique middle section. The substantially “J”-shaped preforms of the flanges allow rolling the coupling means close to the neutral rolling plane. In a last rolling step, the curved preforms of the web and the flanges are straightened to form the finished Z-section sheet pile.

It is well known in the art that grooved rolls used for rolling Z-section sheet-piles have a relatively short lifetime. Due to the absence of mirror symmetry in their section, one has to produce one side of the Z-section sheet pile in a deep groove of the upper roll and the other side in a deep groove of the lower roll. Such extreme roll gap contours result in that the roll surfaces are rapidly worn out and in that possibilities for their reworking are rather limited. They also increase the risk of a roll fracture.

There is consequently a need for a method for rolling a Z-section sheet pile in which the rolls have a longer lifetime and are less exposed to a roll fracture.

SUMMARY OF INVENTION

The invention proposes a method for hot rolling a Z-section sheet pile having a first flange, a second flange, which is substantially parallel to the first flange, an inclined web, a first corner joining the web to the first flange, a second corner joining the web to the second flange, wherein each of the corners has an opening angle α greater than 90°, preferably in the range of 110° to 140°. The proposed method comprises the steps of: (1) rolling a curved preform of the web in successive roll gaps defined by at least one roll pair comprising a grooved upper roll and a grooved lower roll, wherein a preform of the first corner and an adjoining first part of the curved preform of the web are formed in a first groove of the upper roll, in which the latter has e.g. its minimum diameter, and a preform of the second corner and an adjoining second part of the curved preform of the web are formed in a first groove of the lower roll, in which the latter has e.g. its minimum diameter; and (2) subsequently straightening the curved preform of the web between an upper straightening roll and a lower straightening roll. In accordance with one aspect of the present invention, at least in the last roll gaps rolling the curved preform of the web, the diameter of the lower roll decreases in a discontinuous manner in the interval between the first groove in the upper roll and the first groove in the lower roll, and the diameter of the upper roll increases in a complementary manner. Decreasing in a discontinuous manner means that the diameter of the lower roll does not continuously decrease; i.e. there are intermediate portions of the lower roll in the concerned interval, in which the initially decreasing diameter stays substantially constant, and/or in which it increases before it decreases again. In other words, in the interval between the first groove in the upper roll and the first groove in the lower roll, the diameter of the lower roll decreases e.g. in a stepped manner and/or in an undulated manner. It follows that less vertical space is required for rolling the preform of the web; i.e. the minimum diameters of the two rolls may be bigger than with any prior art method of rolling Z-shaped sheet-piles. Consequently, the roll gap contour can be reworked more often, before the minimum diameters of the rolls decrease beyond a limit value. Furthermore, less deep grooves in the rolls also result in smaller rolling torques and in more equal surface speeds along the roll gap contour, i.e. in less mechanical wear of the surfaces of the rolls. In summary, with the proposed method, the rolls wear out less faster and must be reworked less often, but—due to a bigger minimum diameter—can even be reworked more often than with any prior art method for rolling Z-section sheet piles. Last but not least, less deep grooves in the rolls also substantially reduce the risk of a roll fracture. Consequently, with the proposed method, expected total life-time of the rolls can be substantially increased. Finally, it will further be appreciated that the proposed method allows using a relatively thin slab as a starting product for rolling a Z-section sheet pile.

In a preferred embodiment, the diameter of the lower roll decreases, in the interval between the first groove in the upper roll and the first groove in the lower roll, in a an undulated manner, so as to have in this interval at least one intermediate maximum value and one intermediate minimum value. This means e.g. that a third part of the curved preform of the web, which is located between the first part and the second part, is formed partly in a second groove of the lower roll, and partly in a second groove of the upper roll. Due to the fact that rolling of the curved preform of the web is allotted onto at least two grooves in the upper roll and at least two grooves in the lower roll, these grooves may be less deep, i.e. the minimum diameters of the two rolls may be bigger.

In a further embodiment, in the interval between the first groove in the upper roll and the first groove in the lower roll, the diameter of the lower roll decreases then stays constant, before further decreasing. This means e.g. that a third part of the curved preform of the web, which is located between the first part and the second part, is formed between substantially cylindrical portions of the upper roll and the lower roll. Due to the fact that the middle section of the curved preform of the web is rolled—at least partly—between substantially cylindrical roll sections, less vertical space is required for rolling the preform of the web; i.e. the minimum diameters of the two rolls may be bigger than with any prior art method of rolling Z-shaped sheet-piles.

If the centre line of a roll is defined as being the axis (line) about which the roll rotates (i.e. the line passing through the centres of the two bearing journals of the roll) and the nominal diameter of a roll in a roll pair is defined as being the minimum vertical distance between the centre lines of the rolls of the roll pair, the minimum diameter of the lower roll in its—aforementioned—second groove is preferably smaller than the nominal diameter of the lower roll and preferably bigger than the minimum diameter of the lower roll in its first groove; and/or the minimum diameter of the upper roll in its—aforementioned—second groove is preferably smaller than the nominal diameter of the upper roll and preferably bigger than the minimum diameter of the upper roll in its first groove.

(This article comes from FreePatentsOnline.com editor released)

The advantages of steel sheet piling

Materials

Hot-rolled sheet piling is produced to meet one of several applicable ASTM specifications. Most sheet piling is currently produced to ASTM A 572, Standard Specification for High-Strength Low-Alloy Columbium-Vanadium Structural Steel, Grade 50, but may also be available in Grades 60 and 65 (comparable to S 355 GP). Additional specifications typically apply to specific applications. For example, ASTM A 588, Standard Specification for High-Strength Low-Alloy Structural Steel with 50 ksi [345 MPa] Minimum Yield Point to 4-in. [100-mm] Thick, is used for atmospheric weathering applications. For increased corrosion resistance in the splash/tidal zone in marine environments, SSPs can be produced to meet ASTM A 690, Standard Specification for High-Strength Low-Alloy Nickel, Copper, Phosphorus Steel H-Piles and Sheet Piling with Atmospheric Corrosion Resistance for Use in Marine Environments. Like A 572-Grade 50 steel, A 690 has a minimum yield strength of 50 ksi. Although no longer commonly produced, ASTM A 328, Standard Specification for Steel Sheet Piling, with a minimum yield strength of 269 MPa (39 ksi), is the original ASTM sheet piling specification.

Accepted engineering practice is to design steel sheet pilings to 0.65 Fy in longitudinal bending. This applies to Z-profiles and U- profiles. When designing cellular structures, accepted engineering practice is to limit the interlock load on the flat web sheet pile sections to one-half the minimum ultimate interlock strength.

Manufacturing

Steel sheet piling manufacturing relies on a method of steelmaking called electric arc furnace (EAF). In this process, scrap steel is charged into a furnace where electrodes melt the scrap to 1,922 K (3,000ºF). During this first phase, carbon content is monitored closely to ensure compliance with the appropriate ASTM standard. After the carbon content has been verified, other elements, such as silicon, manganese, and are added to create the specific chemistry desired for the final product.

The process of manufacturing a steel sheet piling takes multiple passes from a steel blank or slab. The piling profile is formed at the same time the interlocks are formed. Piling is then cooled, straightened, cut to length and stored for delivery to the customer. Sheet piling lengths can range up to 30 m (98 ft) or more, depending on the section and manufacturer.

Environmental benefits

This manufacturing process is one reason steel sheet pile is very green. Because SSP producers obtain their steel from the electric arc furnace process, which utilises selected recycled steel scrap, they can produce steel to exacting specifications while utilising a scrap content of the finished steel in the range of 99 per cent. The manufacturing process itself has also been improved. In addition to being produced as a green product, sheet piles are installed in a manner that produces no spoils. Therefore, there is no risk of exposure and disposal of hazardous or contaminated materials. At the end of the structure’s life, the piles can be extracted and either reused, if in good enough condition, or recycled. From cradle to grave, steel sheet pile is easy on the environment.

Installation

Detailed site investigation and evaluation allows the designer to determine the structural capacity of the underlying soil and potential structural loads on the steel sheet pile installation. Less obvious, however, is the impact of soil conditions on achieving quality steel sheet piling installations. A thorough knowledge of the site conditions enables an accurate assessment of both the topographical and geographical conditions.

The choice of a suitable driving system is of fundamental importance in order to ensure a safe and successful pile installation. Driving systems can be classified as either impact or vibratory. Impact hammers types include air, hydraulic, or diesel. Vibratory hammers clamp onto the top of the sheet piling sections and through a combination of vibration and hammer weight push the piling into the soil.

Steel sheet piles are installed by foundation contractors who specialise in pile foundations. It is very important that the contractor retained be experienced in using sheet piling. Steel sheet piling, as compared to a close-ended pipe pile, has a small cross-sectional area. It is, therefore, a non-displacement pile which does not cause soil heave or cause additional lateral pressures on nearby existing walls. Driven sheet piles displace soil rather than remove it; therefore the support of adjacent structures is not compromised due to soil movement. In addition, sheet piling will maintain its shape during installation.

(This article comes from Port Technology editor released)

What Is Sheet Piling?

A sheet piling is both a form of retaining wall and the sheets used to make the wall. These sheets are commonly made of metal but may also be vinyl or wood. The sheets are driven into the ground and locked together to form a tight physical barrier to water, insects and plant life. These types of retaining walls are common in areas with loose sand and soil, as they are relatively easy to place and maintain. Small walls are generally two parts below ground and one part above, but larger walls may have a larger underground area or additional supports.

The material used to make a sheet piling varies based on the desired use of the wall. The most common and general purpose material is metal, but certain plastics and wood have uses in specific circumstances. The metal used to make sheet pilings is almost always galvanized steel. This metal has undergone a process to make it more resistant to environmental dangers, such as impacts and moisture.

There are a variety of common sheet piling shapes. Many of the basic styles have alternating high and low flat surfaces connected by sloped sides; much like the corrugation inside cardboard. This shape both improves the metal’s structural stability and makes it easier to stack for storage or transport. With this design, there is typically a break in the middle of the high or low flat spot.

These breaks are what make the sheet pilings so effective. The edge of each piece is specially designed to connect to the edge of the piece next to it. This allows the wall to be of any size or shape as well as follow the contours of the land. By making the break in an open area, rather than a corner or intersection, pieces of different design can work together to make up the larger wall.

Sheet piling retaining walls are used in many different types of construction. In some areas, they are placed underground a small distance away from the foundation of a structure. This helps prevent water from reaching the building’s true foundation. Even so, their most common use is as retaining walls in loose terrain. Since the walls are so thin, it is easy to push them down into the loose ground, and their interlocking plates allow them to work around underground obstructions, such as rocks or utility lines.

In order to maintain stability and keep its shape, a sheet piling needs twice as much underground as above ground. In particularly loose areas, or with larger walls, other measures are sometimes taken. Diagonal supports are the easiest additional support method and are placed on the low side of the wall. In addition, anchor lines are sometime connected to the wall and run diagonally up through the retained material and anchor on the surface.

(This article comes from wisegeek.com editor released)

Advantages of Pressed-in Piles as Prefabricated Pile

Proven Quality as Prefabricated Structural Materials

Prefabricated piles are manufactured by automated production in the factory and guarantee uniform quality. In addition they can be produced beforehand and stored easily in the time when material costs are cheap. The appropriate supply of the prefabricated piles allows the completion of construction work on site at the earliest possible moment.

Wide Range of Application

Self-standing wall structures can be constructed only by installing prefabricated piles from the ground. The structure also can be increased the strength by choosing strut structure, tie-rod structure or double pile structure. Prefabricated piles are widely applicable not only to temporary structures such as coffering and retaining wall, but also to permanent structures such as river revetment, quay wall, road retaining wall, and building frame of underground facility.

Shortening Work Duration

Various shapes, lengths and thicknesses of prefabricated piles contribute to economic design. The appropriate use of prefabricated piles attains overall cost saving through a shortening of the work duration and a reduction of labour. In addition some of the steel sheet piles can be used repeatedly as the steel products for temporary structures, it is possible to reduce construction cost.

(This article comes from GIKEN LTD. editor released)

ROCK AND SOIL ANCHORS

Rock anchors are either high strength bars or strand drilled and grouted into bedrock and/or soil in order to resist forces. Structures need anchors to counteract the uplift and other forces acting on foundations.

SDI’s economical ground anchor systems have been used with exceptional results to:

  • Prevent uplift and overturning forces of walls, towers, and conveyors
  • Permanently stabilize buildings, dams, and bridges
  • Provide landslide control

Customers rely on our field experts for design assistance, anchor selection and geotechnical construction that meets — and exceeds — recommendations set by the Post Tensioning Institute (PTI) for prestressed rock and soil anchors.

  • Capacities up to 500 Tons (1,000 kips)
  • Both bar and strand anchor materials available
  • Temporary and permanent applications include multiple corrosion protection for permanent anchors
  • Installed in all types of soil, over burden and rock conditions at any inclination
  • Steep embankment and high reach / extended elevation drilling

To ensure optimum performance, SDI conducts performance and proof testing on individual anchors using calibrated test jacks, gauges and load cells.

(This article comes from Shaft Drillers International editor released)

GROUND ANCHORS

Ground anchors consisting of cables or rods connected to a bearing plate are often used for the stabilization of steep slopes or slopes consisting of softer soils, as well as the enhancement of embankment or foundation soil capacity, or to prevent excessive erosion and landslides. The use of steel ground anchors is often constrained by overall durability in placement (due to weight), and the difficulty in maintaining tension levels in the anchor. Anchor systems fabricated from fiber reinforced composite materials show a number of benefits compared to conventional systems for the following reasons:

  • Enhanced durability including resistance to corrosion and resistance to alkalis and solutions in soils increase their life and greatly reduce the need for maintenance, thereby decreasing life-cycle costs.
  • Lighter weight results in easier transportation of cables to site, and increases the efficiency of handling and placement.
  • Enhanced tensile strength coupled with lighter weight and enhanced mechanical properties results in greater safety during installation in areas with limited clearance.

In most cases, it is possible to use conventional jacking systems and still realize greater flexibility in placement and tensioning in difficult ground formations.

Composite ground anchors generically consist of three parts:

  1. The anchorage is generally a stainless steel sheath with an anchor nut/plate through which the composite cable is run. The anchorage is usually filled with a non-shrink expansive cement mortar that ensures fixity and no slippage. The anchorage also is used to fasten the system to the outside structure.
  2. The cable can consist of multiple rods that are separate or braided together, or a single rod.
  3. A sheath or sleeve made from polyethylene or PVC that is fitted around the free anchor length of the cables.

System Details

Four different composite ground anchor systems are available.

      1. Leadline Type System: Marketed by Mitsubishi Chemical Corporation and Chemical Grouting Company, Ltd., this type uses carbon fiber reinforced epoxy cables that usually have nine 8 mm diameter rods arranged in a circle with a single rod in the center. Each rod has cross-type indentations or spirals cut into it to provide interlock and stress transfer.
      2. CFCC Type System: Marketed by Tokyo Rope Manufacturing Co., Ltd., this type uses carbon fiber reinforced epoxy cables that are formed from 7 12.5 mm diameter rods twisted together and covered with epoxy.
      3. FiBRA Type System: Marketed by Shinko Wire Co., Ltd., this type uses aramid fiber reinforced epoxy cables that are formed through the braiding of individual strands into a tight bundle with 10.4 mm nominal diameter.
      4. Technora Rod Type System: Marketed by Sumitomo Construction Co., Ltd., and Teijin, Ltd., this type uses aramid fiber reinforced vinylester cables that are formed through the use of nine individual 7.4 mm diameter rods that, like the Leadline system, are isolated but brought together in the anchorage. Unlike the Leadline system, wherein the rods are arranged in a circle with a single rod at the center, these rods are brought into close contact.

(This article comes from wtec.org editor released)

Manta Ray Installation

Installation Equipment

Drive Steel
Drive steel and accessories are available from Foresight Products for all Manta Ray and Stingray anchors in basic lengths of 3 feet, 6 feet, and 8 feet. Multiple sections are coupled together with specialized couplers to achieve the required depth of installation. Manta Ray and Stingray drive steel are not interchangeable.

Load Locking Kits
For Manta Ray, the LL-1 is a 10-ton fast acting jack with an 8-inch stroke. The direct reading gauge and rod gripping jaws make load locking easy and quick. For high capacity Stingrays, the LL-40 is a 20-ton jack with a 10-inch stroke. The base and jack are self-aligning to the actual installed angle of the anchor. Both kits require open center hydraulic flow of 2 to 8 gallons per minute and a maximum pressure of 2,000 psi. A power supply is not included with these load-locking kits, it must be provided separately. Foresight Products models GPU18- 8 or GPU-2 are suitable for the LL-1. GPU18-8 is required for the LL-40.

Installation Methods

Vehicle Mounted Breakers or Compactors :
Boom mounted demolitions or compactions are very effective for driving Manta Ray and Stingray anchors.
This method requires a special tool in the breaker or a socket welded to the bottom of the compactor to hold the drive steel.
Skid steer loaders, backhoes or excavators work well.

4,000 to 16,000 lb. vehicles with 250 to 500 foot-pound pavement breakers are best for Manta Rays, and 16,000 to 30,000 lb. vehicles with 500 to 1,000 foot-pound pavement breakers are best for Stingrays.

Breaker tools and vibro sockets are available upon request.

Rock Drills :
Top hammer or down-the-hole hammer rock drills are very effective for installation of Manta Ray and Stingray anchors.
For hard soil or weak rock installations, the drill can be used to drill a pilot hole. We can provide striker bar adapters for these types of drills.
Rock drilling steel can also be modified to drive Manta Rays and Stingrays.

Manual Installation :
In some applications, Manta Ray anchors are driven into the soil with a 90 lb. pavement breaker and coupled drive steel.
Pneumatic or hydraulic breakers are acceptable, but a 90 lb. weight class breaker is necessary.
Manual installation of Stingray anchors is not recommended.

(This article comes from ABC Diving editor released)

Earth Anchors (DUCKBILL)

Installation

1. Drive DUCKBILL to desire depth

DUCKBILL anchor are driven into the soil using a hammer and drive steel (a small jack hammer can be used together with power drive steel). As the anchor is being driven, it is actually compacting the soil around the anchor head. Once the anchor is at the proper depth, the drive steel is removed.

2. Set the DUCKBILL in soil

To set the anchor in normal soil, wrap the wire rope around the drive steel or insert rod through loop in wire rope and pull upward a distance approx. The lenght of the anchor body. Or, use the DUCKBILL Anchor Hook accessory. The upward pull on the wire rope rotates the anchor into a perpendicular load lock position in undusturbed soil.

Multi Purpose

DUCKBILL Multi Purpose Earth Anchor Systems

Secure any object to deter theft and prevent unwanted movement

DUCKBILL Earth Anchors are used worldwide to secure items that can be stolen, moved or blown down. Sizes are available for any application.

One-man installation capabilitys without the need for digging, expensive equipment or special skills saves time and labour. And DUCKBILLS are safer that conventional anchors because the leave no rigid rods or stakes above ground to cause injury.

DUCKBILLS are designed with lenght of galvanized wire rope or galvanized wire rope combined with proof coil chain long enough to allow enough movement for moving or maintenance.

DUCKBILLS are intended for light duty applications in normal soils and peroidic condition inspections are recomended.

For Highly corrsive enviroments, DUCKBILL Anchors can be anodized, fabricated with stainless steel wire rope, plastic impregnated wire rope or other corrosion-resistant solutions.

(This article comes from ropecon.co.za editor released)