Ground Anchor Load Testing

Ground Anchor Load Testing:

A unique aspect of ground anchors, as compared to other structural systems, is that every ground anchor that is to be part of a completed structure is load tested to verify its load capacity and load-deformation behavior before being put into service. The acceptance or rejection of ground anchors is determined based on the results of:

1- Performance tests;

Performance tests involve incremental loading and unloading of a production anchor. The performance test is used to verify anchor capacity, establish load-deformation behavior, identify causes of anchor movement, and to verify that the actual unbonded length is equal to or greater than that assumed in the anchor design.

2- Proof tests;

The proof test involves a single load cycle and a load hold at the test load. The magnitude of the applied load is measured using the jack pressure gauge.

3- Extended creep tests.

An extended creep test is a long duration test (e.g., approximately 8 hours) that is used to evaluate creep deformations of anchors.

The results of these tests are compared to specified acceptance criteria to evaluate whether the ground anchor can be put into service. The acceptance criteria are based on allowable creep and elastic movements of the anchor during load testing.

Advantages

• Execute excavations neatly to create large construction plan without using props in order to make mechanized excavation.
• Keep excavation walls sustainable, make very deep excavations without depending on the basement structure.
• Anchors combine with soft retaining walls to redistribute the intemal forces of wall structure, so this can reduce the size, depth of steel bars in retaining walls.

Disadvantages

• It is necessary to use specifed equipment, exprienced professional engineers.
• It is difficult to apply anchors in weak soil and to implement anchors with great depth.
• Ground Anchor execution would affect the land of surrounding construction works, which must be accepted by their owners.