Some Technical Performance Issues to Manta Ray and Stingray Earth Anchors

Manta Ray and Stingray anchors are tensile anchors designed to work well in soils with SPT blow counts (N) from 7 to 50. The smaller anchor models are used in harder soils or where lowers loads are required. Larger anchors are used in softer soils. In harder soils, the installed capacity is limited by the ultimate strength of the anchor. In softer soils, it is limited by the soil strength. Soils with blow counts of 35 to 50 and higher, often require the installer to drill a 4-inch diameter pilot hole for Manta Ray or a 6-inch pilot hole for Stingray prior to installation in order to achieve an efficient installation time.

Although they are not intended for installation in rock, some models can be successfully installed into rock formations with low Rock Quality Designation (RQD). Typically, a pilot hole is required for these installations, but sometimes anchors can be simply driven into weathered, layered, decomposing rock.

Manta Ray and Stingray anchors are designed to react tensile loads along the axis of the anchor rod. They are not designed to react compressive, lateral, or shear loads, however, they can be made to do so by the addition of grout, which will increase the holding capacity,
sometimes very significantly.

The increase is dependant upon the grout length and soil type. Both the CTB and SCR exceed the deformation characteristics of ASTM 615 rebar.

For retaining structures, Manta Ray anchors should be installed a minimum of 6 feet behind the failure place after proof testing. Stingray anchors should be installed a minimum of 10 feet behind the failure plane after proof testing. A minimum overburden of 4 feet must be maintained for Manta Ray anchors and 7 feet for Stingray anchors.

Manta Ray and Stingray anchors can be proof tested up to 90% of yield strength. Working loads are typically between 50% and 90% of the proof test value.

(This article comes from GeoSolutions editor released)

How To Install Earth Anchors

Use suitable trees as the posts at deer fence corners wherever possible. Lacking trees, you need earth anchors attached with a heavy wire or cable. The earth anchor system can be used effectively with any deer fence corner post or corner approach post set in a cement footing.

This earth anchor system is appealing because all you have to do is screw the anchor into the ground (this can be hard in places with rocks or roots) and run a heavy metal wire designed for outdoor use between a secure point on the deer fence post and the earth anchor’s handle. In most cases, compared to deer fence braces (an alternate bracing system), we have found earth anchors easier to install, less expensive, less visible, and more effective.

You can anchor a corner with earth anchors in two ways. One way anchors the corner post and requires only one earth anchor; but it leaves the earth anchor and its attachment cable outside the fence line, creating a potential lawnmower problem and tripping hazard. The other method braces the two posts approaching the corner post. This requires two earth anchors instead of one, but it puts the earth anchors and their cables right along the deer fence line, removing the lawnmower problem and tripping hazard.

If you are using the latter method, those parts of the deer fence between the corner approach posts and the corner post are not secured against sideways stress. So, where snow loads or falling tree branches are a problem, set the corner approach posts close to the corner post (within 6 to 10 feet, the closer the better). This will shorten the segments of fence that are not anchored.

(This article comes from McGregorDeerFence editor released)

Steel Sheet Pile Wall Corrosion Protection

Roen Salvage Company has partnered with Acotec to provide corrosion protection by applying the Humidur coating system on steel sheet pile walls using the DZI Mobile Cofferdam. With the Humidur coating system, we can repair and stop corrosion at a fraction of the cost of replacing the entire steel sheet pile wall.

The DZI Mobile Cofferdam can be quickly transported and set up to be used with almost any steel sheet pile dock wall. Once the mobile cofferdam is in place, a variety of work can occur inside the dewatered cofferdam, for example:

  • Existing corrosion inspection by the owner and/or engineer
  • Pressure washing to remove the corroded layer of steel
  • Welding supplemental steel plates onto severely corroded areas of the wall
  • Sand blasting to prepare the cleaned steel surface for painting
  • Application of the corrosion-stopping Humidur coating; or
  • Bolting on large pre-coated steel protection plates in front of the cleaned existing wall
  • Progress inspections of the sheet pile wall by the owner and/or engineer

Using this Humidur coating system with the DZI Mobile Cofferdam, Roen Salvage can rehabilitate over a mile of steel sheet pile wall in less than six months.

(This article comes from ROEN SALVAGE editor released)

Savings Brought by Screw Piles

Screw piles provide a durable foundation method for all kinds of construction. They offer a cost-effective solution without excavation and insulation work, and installation is fast, whether done mechanically or by rotating into place by hand.

Screw pile foundations are still used extensively, and their usage has extended from lighthouses to rail, telecommunications, roads, and numerous other industries where fast installation is required, or building work takes place close to existing structures.

Most industries use screw pile foundations due to the cost efficiencies and – increasingly – the reduced environmental impact. ‘Screwing’ the foundations in the ground means that there is less soil displacement so excess soil does not need to be transported from the site, saving on transportation costs and reducing the carbon footprint of the project.

Savings brought by screw piles:

  • fast installation saves on labour and equipment costs
  • you can perform the installation yourself using e.g. a crowbar
  • no large-scale earthworks, frost insulation, drainage, or casting and mould work
  • inexpensive to transport and store
  • The carrying capacity provided by the helix saves on pile length
  • almost invariably requires only one site visit
  • light installation equipment
  • the environment stays clean and undamaged

(This article comes from PaaluPiste Oy and Wikipedia editor released)

Introduction to Helical Anchors

Helical anchors have been in use for more than 170 years. In 1838 a lighthouse was built upon helical piers designed by an Irish engineer, Alexander Mitchell. Sporadic use of helical piers has been documented throughout the 19th and early 20th centuries mainly for supporting structures and bridges built upon weak or wet soil.

When hydraulic motors became readily available in the 1960’s, which allowed for easy and fast installation of helical piers, their popularity flourished. Electric utility companies began to use helical piers for tie down anchors on transmission towers and for guy wires on utility poles.

Helical piers are ideal for applications where there is a need to resist both tension and axial compression forces. Some examples of structures having combination forces are metal buildings, canopies and monopole telecommunication tower foundations.

Current uses for helical piers include underpinning foundations for commercial and residential structures, foundation repair, light standards, retaining walls tieback anchors, pipeline and pumping equipment supports, elevated walkways, bridge abutments, and numerous uses in the electric utility industry. Many times helical anchors are the best solution for your foundation repair project due to one of the following factors:

  • Ease of Installation
  • Little to No Vibration
  • Immediate Load Transfer upon Installation
  • Installed Torque Correlates to Capacity
  • Easily Load Tested to Verify Capacity
  • Installs Below Active Soils
  • All Weather Installation
  • Little to No Disturbance to Jobsite

(This article comes from Earth Contact Products editor released)

Tie-back Anchors for Retaining Walls

The principle of using tie-back anchors to support earth-retaining walls is essentially to remove the need for structs or shores within the area to be excavated.

The anchors are tensioned and the load locked in order to limit lateral movement of the wall.

Suitable for resisting lateral movement of exposed embedded retaining walls where adequate resistance to slipping or yielding of the soil or rock mass in the anchor zone is avaliable.

The anchor system may be required for temporary or permanent support for the structure, or as remedial works. The highest anchor loads are achieved in sound rock; but dense granular soil can provide ultimate capacity up to 2,000 kN. Anchor capacity in stiff clays depends on the soil shear strength and whether fracture grouting or under-reaming is carried out to improve the pull-out resistance. Note that permission must be obtained to drill and grout inclined anchors under adjacent property.

(This article comes from An Introduction to Geotechnical Processes editor released)

Soil Nailing and Its Action Mechanism

In recent years, the construction of the city with a large number of high-rise buildings, deep excavation technology is developing rapidly. Soil nailing is the recent development of a new type of retaining structure for the excavated soil and slope stability. It is composed of dense soil nailing group, reinforced in-situ soil and spraying concrete pavement waterproof and the necessary system. It can form a similar gravity retaining wall, in order to resist the pressures after the wall and other forces, so that the excavation slope stability. Because of its construction convenient, simple equipment, excavation and support operations can be carried out at the same time, short construction period, low cost, low pollution, stable and reliable and many other technical and economic advantages, soil nailing spread rapidly in the country, especially in areas of low groundwater levels.

Mechanism of soil nailing

Soil with low shear strength, tensile strength almost can be ignored, but the soil has a certain structural integrity. When excavation of foundation pit, soil in the critical height of slope is in an upright position, when more than the depth or overload on the ground and under the effect of other factors, the sudden overall damage will occur. Traditional retaining structure are based on passive restriction mechanism. Namely by its own strength and stiffness, bear the following lateral earth pressure, prevents damage to the overall stability of soil. Soil nailing is set in soil body with a certain length and density of soil nailing, work together with the soil and make up for a lack of tensile and shear strength of soil itself. Soil nailing and soil work together to form a composite soil that can greatly increase the strength and stiffness of the undisturbed soil. Experiment shows that the vertical carrying capacity of the soil nailing wall in the top about one times more than a plain wall. More importantly, soil nailing structure is recognized as a good ductile characteristics. Loaded during prime soil slope does not occur as sudden landslide, slope provides for the repair time, and reduce the loss caused by the slope of the slump.

Features of Steel Sheet Pile Construction Method

As a green-infrastructure reusable material, U-shaped hot rolled sheet pile has meeting the engineering requirements, functional, reliable, ease of use, safety, environmental protection, and other unique advantages with its efficient, durable, simple, lightweight and excellent sectional structure impervious seal shape.

Steel sheet pile with anchor (or support), and other devices constitute integral steel structure, through the pile of larson lock mouth bite each other. Compared with other methods, the steel sheet pile construction has the following distinctive features:

  • The construction is simple, occupied area is small, the construction operation is flexible and simple.
  • Quick operation, short construction period, suitable for the implementation of floods, landslides, subsidence, quicksand disasters such as fast repair.
  • Light structure. Compared with other structures, it is light structure, strong bearing capacity, monomer good vibration resistance.
  • Lie between water is strong, can make the structure quick check water or lost circulation, prevent infiltration, easy construction.
  • Durability, in a relatively harsh environment in the life of up to 50 years.
  • Construction of environmental protection, soil and concrete consumption greatly reduced, effective protection of land resources.
  • Good repeatability, repeated use of 20 ~ 30 times in temporary engineering.

Features of Strand Anchor

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Strand anchors consist of three main components: the anchor head, a steel tendon – divided into the bond section and free length – and the grout body.
The steel tendon is constructed from a number of 7-wire prestressing strands.

Features:

  • Nationally approved system with internal and external quality control
  • Can be closely matched to the required loads by selecting the number of strands, strand cross-section and steel grade
  • Longer anchor lengths can be produced without joints
  • Relatively low dead weight and small diameter
  • Ease of installation thanks to high anchor flexibility
  • Efficient to transport due to low space requirement for transport and storage (anchors are supplied coiled up)

(This article comes from ANP Systems GmbH editor released)

Self-drilling Hollow Bar Anchor System

The self-drilling hollow bar anchor system consists of a hollow threaded bar with an attached drill bit that can perform drilling, anchoring and grouting in a single operation. The hollow bar allows air and water to freely pass through the bar during drilling to remove debris and then allow grout to be injected immediately after drilling is completed. Grout fills the hollow bar and completely covers the entire bolt. Couplings can be used to join hollow bars and extend the bolt length while nuts and plates are used to provide the required tension.

Self-drilling hollow bar anchor system is the most common used system for rock mass stabilization, especially in tunneling, underground mining and ground engineering industry. It is mainly used for the supporting engineering in the loose and broken rock stratal with difficult to drilling hole. It provides the optimal solution for soil nailing, lock bolting, micro-piling.

Self-drilling hollow bar anchor system fulfills current and increasing demands of the tunneling, mining industry and ground engineering for safer and faster production. The system provides advantages for all areas of its applications, where boreholes would require the time consuming drilling with casing systems in unconsolidated or cohesive soil.

(This article comes from ACEDRILLS editor released)