How Do Ground Anchors Work? | The Load Transfer Explained

A ground anchor transfers tensile force from a structure into deeper, more competent soil or rock through a drilled, grouted, and tensioned steel tendon.

Ground anchors are the unsung heroes holding up retaining walls, stabilizing slopes, and resisting the forces that would otherwise push structures over. Whether you’re securing a manufactured home or supporting a bridge abutment, the principle is the same: lock a tendon into stable ground and tension it so the earth itself resists movement.

Here’s how the system actually works, from the parts involved to the installation sequence that makes it hold.

The Anatomy of a Ground Anchor

Every ground anchor is built around three distinct zones that each play a specific role in transferring load. The head assembly connects the tendon to the structure being supported, the free length runs through the ground without bonding to it, and the bonded length — also called the root or anchorage zone — is grouted firmly into the soil or rock.

The tendon itself is the load-carrying element. It’s typically a steel bar or multi-strand cable engineered for high tensile resistance. For heavier applications, multi-strand tendons are more common because they offer higher tensile resistance and are easier to handle on site. The free length isolates the tendon from the ground so no load transfers until you reach the bonded zone.

What Happens During Installation

Installing a ground anchor isn’t a screw-in operation. It’s a precise sequence that requires drilling, grouting, curing, and tensioning. The typical process runs like this:

• Drill a hole at the required angle and depth — usually into competent soil or rock beyond the potential failure surface.
• Insert the tendon and anchor assembly into the borehole.
• Grout the bonded section to create the load-transfer zone where force will move into the ground.
• Let the grout cure to develop its full bond strength.
• Tension the tendon with hydraulic jacks or a prestressing system.
• Lock off the tendon at the anchor head so the imposed prestress stays in place.

The prestressing step is what makes these anchors active rather than passive. By tensioning the tendon before movement occurs, the anchor limits deformation of the supported structure instead of merely reacting to it after the fact. The bonded length is what distributes that prestressing force to the surrounding soil or rock.

Types and Design Variations

Ground anchors come in several configurations depending on the soil conditions and the load they need to resist. U.S. practice classifies rock anchors by how they’re grouted: Type A anchors are straight shaft gravity-grouted, Type B are straight shaft pressure-grouted, Type C are post-grouted, and Type D are under-reamed. Each type suits different ground conditions and load requirements.

In manufactured-home applications specifically, the anchor assembly transfers anchoring loads to the ground under U.S. code references in 24 CFR 3285.5. These anchors face the same principles but on a smaller scale, with the goal of resisting wind uplift and lateral movement.

Common Mistakes and Design Pitfalls

The most frequent failure in ground anchor design comes down to placement: putting the bonded zone inside the potential failure wedge instead of beyond it. The anchor’s root needs to sit in stable ground beyond the slip surface. If the bonded zone sits inside the failure envelope, the whole anchor can pull out with the moving soil.

Other common problems include confusing the free length with the bonded zone — only the root should transfer load to the ground — and choosing the wrong tendon type for the application. Spacing and bond length also matter.

One important point: ground anchors are structural elements, not universal screw-in devices. Many geotechnical anchors require drilling, grouting, curing, and tensioning. They should be designed and installed by qualified professionals because performance depends heavily on soil conditions, grout bond quality, and prestress levels.

If you’re securing a smaller structure like a shed, fence, or garden building rather than a retaining wall, a no-dig ground anchor review covers screw-in options that work without drilling or grouting. Those operate on a simpler principle — physical penetration and soil friction instead of grout bond — but for permanent engineered structures, the drilled-and-grouted approach remains the standard.