Types and Application of Ground Anchor

Ground anchor in accordance with the set form of a pile anchor and horizontal anchor two. Pile type anchor is suitable for fixing the cable wind with little force, and rarely used in structure hoisting. Horizontal anchor is a few logs (square wood or steel) tied together with wire rope, placed horizontally at the end of the anchor, wire rope at the end of the pit from the pit leads, rope and the ground angle should be equal to the cable wind And the ground angle, and then use the earth and stone backfill compaction. Logging depth and the number of logs should be based on the size and soil anchorage force may be determined, the general buried depth of 1.5 ~ 2m, the force can be 30 ~ 150kN, log length of 1 ~ 1.5m. When the tensile force exceeds 75kN, the anchor bar should be increased. When the tension is greater than 150kN, the application of columns and wooden walls to strengthen to increase the lateral resistance of soil.

Heavy-duty anchors (such as heavy-duty mast cranes and cable-wind anchors) are made of reinforced concrete.

Horizontal anchor installation and use should be noted:

  1. Ground anchors should be buried in hard soil where the ground is not wet, not water.
  2. Do not use decaying wood for anchor, crossbar tied cable at four corners to use angle reinforcement. Wire rope to be bound firmly.
  3. Important ground anchors should be calculated, after the need to be tested.
  4. After the anchor is buried, it should undergo a detailed inspection before it can be used formally. Use a person responsible for the guard, such as deformation, should take immediate measures to strengthen.

What is Ground Anchor?

Definition – What does Ground Anchor mean?

Ground Anchor is a lightweight tool designed to transfer home anchoring to the ground. It is easy to install and it consists of cables and rods that are connected to a bearing plate thus used for stabilization of steep slopes. Initially, it was used in the United States to support excavation systems. The tool is often used to transmit a tensile load to the ground. It is installed in grout-filled drill holes. The main components of the tool are anchorage, free stressing length and bond length.

Petropedia explains Ground Anchor

There are two main types of Ground Anchors namely, straight shaft pressure grouted ground anchors and straight shaft gravity grouted ground anchors. The straight shaft gravity grouted ground anchors are used for various drilling and auger methods, whereas the pressure grouted ground anchors are suitable for granular soils. The major uses of Ground Anchors are:

  • To retain the walls of erosion control system
  • To provide structural support to temporary buildings
  • To offer security in anchoring small aircraft

Moreover, Ground Anchors enhance the durability of devices and include resistance to corrosion thereby decreasing their life cycle costs.

(This article comes from Petropedia editor released)

EARTH, SOIL AND GROUND ANCHORS – MANTA RAY

In special circumstances, the footprints of landscape, swimming pools, slabs, or even your home might be too close (within 10 to 12 foot) to your seawall. Manta Ray Earth Anchors can be driven underneath the obstruction.  Ground Anchors can be incorporated with a new seawall in front of the old in areas where you cannot safely replace the existing seawall. Soil and Earth Anchors are more cost effective for repair, and doesn’t require excavation, digging or disturbing the landscape.  Earth anchors sizes, spacing, and torque specifications are engineering factors that are used to place the anchors where needed.

Advantages of Earth Anchors: 

1. No Excavation, Deep Holes or Digging

2. Environment & Landscape Sensitive Installs

3. Very Low Soil or Landscape Disturbances

4. Lower Cost then Replacing a Seawall

5. Effectively Repairs and Stabilizes Failing Seawalls

6. Corrosive Protection for All Weather Environments

7. Up to 20 Tons of Capacity for Seawall Stabilization

(This article comes from Stronghold Marine Construction editor released)

Braced sheet piling walls with ground anchors

The bracing of sheet piling walls using ground anchors facilitates deep excavations whilst leaving the area free of obstacles.

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  • This method enables the undertaking of deep excavations whilst limiting deformation to the wall.
  • Providing it is possible to implement this method, the use of anchors for bracing sheet piling screens enables the undertaking of excavations in the proximity of elements which must be protected (buildings, installations, communications networks, etc.).
  • The excavation must be carried is needed more than one phase in order that the anchors can be installed and stress tested before proceeding with the other work.
  • This type of bracing makes it possible to undertake the excavation of large enclosures in a variety of geometries.
  • The excavation remains completely free of obstacles, enabling the optimum performance of the work to be carried out in its interior.

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(This article comes from www.ischebeck.es editor released)

Ground Anchors

The idea of installing retaining systems without tie-back anchoring is almost inconceivable nowadays.

Excavation pits with no obstructive strutting have been the standard ever since. Today ground anchors are used to secure pile walls, sheet piles, Mixed-in-Place walls or diaphragm walls, as well as steep slopes, support embankments and quay walls. Installing ground anchors is a technically elegant, cost-effective and, above all, operationally efficient solution for many construction projects. Whether for temporary or permanent use, in single-rod or strand anchor configuration, in the dry or protecting against pressing groundwater, the ground anchor is usable in all kinds of soil and in rock. Experienced, continuously trained drilling crews, high-performance special equipment and comprehensive quality control ensure rapid, technically fault-free execution of ground anchors.

Types of the Construction Method

  • Temporary anchors

    Temporary anchors, in single-rod or strand anchor configuration, which can be removed fully or partially, are used to secure retaining walls for a maximum of two years. They are quick to install and highly cost-effective. The load-bearing behaviour of each anchor is tested and logged during the acceptance procedure. Strand anchors are delivered to the site in coils, which means they can also be used in tight operating environments.

  • Permanent anchors

    Permanent anchors are ground anchors usable for longer than two years, and thus part of a permanent structure. Permanent anchors are executed as strand anchors, single-rod corrugated tube anchors or single-rod pressure tube anchors. The steel tendon and anchor head are protected against corrosion by special measures. Each hollow space in the anchor head is filled in with permanently plastic corrosion-proof compound.

(This article comes from BAUER Fundaciones Panamá 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)

Design and Application of a Field Sensing System for Ground Anchors in Slopes

In a ground anchor system, cables or tendons connected to a bearing plate are used for stabilization of slopes. Then, the stability of a slope is dependent on maintaining the tension levels in the cables. So far, no research on a strain-based field sensing system for ground anchors has been reported. Therefore, in this study, a practical monitoring system for long-term sensing of tension levels in tendons for anchor-reinforced slopes is proposed. The system for anchor-reinforced slopes is composed of: (1) load cells based on vibrating wire strain gauges (VWSGs), (2) wireless sensor nodes which receive and process the signals from load cells and then transmit the result to a master node through local area communication, (3) master nodes which transmit the data sent from sensor nodes to the server through mobile communication, and (4) a server located at the base station. The system was applied to field sensing of ground anchors in the 62 m-long and 26 m-high slope at the side of the highway. Based on the long-term monitoring, the safety of the anchor-reinforced slope can be secured by the timely applications of re-tensioning processes in tendons.

A ground anchor system in slopes is used to stabilize a slope and thus to prevent a slope failure. The purpose of the anchor system can be achieved by transferring the residual forces of anchors to the compression forces on ground. Since a pre-stressing technique was utilized on the Cheurfas Dam in Algeria in 1935, various forms of ground anchors have been developed and utilized in numerous structures, including bridges, buoyancy structures below ground water level, and tunnels, in addition to the slopes. Nevertheless, most ground anchors have an identical basic mechanism of delivering residual force of a tendon to the ground.

All anchor systems have some of key common elements. According to EN 1537, a ground anchor is composed of three parts: (1) ground anchor body (2) anchor head, and (3) relevant accessories. Ground anchor body is again divided into two parts: free anchor length and fixed anchor length. The part of free anchor length where strand or rod is covered by sheath delivers the residual force from anchor head to the part of fixed anchor length where tendon is grouted. A part of fixed anchor length again delivers residual force to ground by friction and compression. Depending on the types, ground anchor systems requires its own relevant accessories (e.g., wedge, nut and saddle of anchor head) to facilitate the operation of the mechanism.

The ground anchor is designed to avoid the possible failure mechanisms by considering: (1) overall stability of the anchor-reinforced slope, (2) inner stability of the anchor, and (3) stability of the bearing block. The overall stability of anchor-reinforced slope is assessed by structural analysis on the reinforcement effect of anchor on the predicted failure section. Various factors, including introduced residual force, decrease of residual force at installation, creep of the ground, and relaxation of tendon are considered in the analysis.

Securing the inner stability of the anchor is mandatory to prevent the occurrence of failure between grout body and ground, failure between grout and tendon, and tendon fracture. Also, the bearing block which serves the role of distributing the residual force of the anchor on the surface of slopes should not be destroyed by shear force or moment. During the service period, current states of reinforcement can be obtained through a monitoring system and compared with the intended design or expectation. The residual force of anchor on the reinforced slope is directly connected to various failure scenarios of system. Hence it becomes the main target of slope monitoring.

(This article comes from MDPI AG editor released)