Method

Advantages

Limitations

Relief (Overcoring)

Most developed technique in both theory and practice.

Operated at 103 - 102 m3 rock volume.

Scattering due to small rock volume. Requires drill rig.

Only 2D.

Doorstopper

Works in jointed and high stressed rocks.

Only 2D. Requires drill rig.

Flat jacking

Direct measurement of the compressive stress present.

Both 2D/3D within the masonry.

Useful for determining stress gradients within a masonry wall or column.

Operated at 0.5 - 2 m3 rock volume.

Requires the cutting of a slot in the masonry, which may cause damage to the structure.

Can be time-consuming and labor-intensive.

Requires specialized equipment and trained personnel to perform the test.

Hydraulic fracturing (HF)

Measurements in existing hole. Low scattering in the results. Involves a fairly large rock volume. Quick.

Operated at 0.5 - 50 m3 rock volume.

Only 2D. The theoretical limitations in the evaluation of σh.

Disturbs water chemistry.

Only 2D.

HTPF

Measurements in existing hole. Can be applied when high stresses exist and overcoring and hydraulic fracturing fail.

Both 2D/3D.

Operated at 1 - 10 m3 rock volume.

Time-consuming. Requires existing fractures in the hole with varying strikes and dips.