DYWI ® Drill System

Stressing and Testing

Soil Nail Testing
Soil Nail Testing is used to establish the bond stress within the stable zone of a slope. Load generated in the wedge (retained) zone is usually discounted as it does not contribute to the underlying stability of the nailed slope. As DYWI ® Drill Hollow Bar soil nails are typically fully grouted (therefore fully bonded), it is necessary to either wash back the grout in the wedge zone with a lance, or to establish the influence of the wedge zone bond on the final load, so that an accurate assessment of the load in the stable zone can be made.


Nail load is measured through a pressure gauge incorporated in the jack circuit, with extension recorded by a dial gauge mounted independently.

Bearing surfaces for the jack platform should be perpendicular to the angle of installation and have sufficient bearing area to resist settlement as the nail is tested. An alignment load in the jack will ensure correct orientation of the soil nail prior to measuring its extension (see DSI Stressing and Testing Services).

Micropile Testing
A range of tests are used to establish the settlement characteristics of micro piles. Compression testing generally falls into two categories, static or dynamic. Static testing employs anchor piles or kentledge to provide the reaction against which the micropile is loaded; displacement can then measured against load. The dynamic pile test utilises a falling mass to induce a stress wave within the pile. The characteristics of the wave can then be analysed with software simulation programmes to separate the skin friction and end-bearing elements (if applicable) of the pile.

Tensile pile testing involves loading the micropile with a jack, from a bearing platform that spans outside the cone of influence. Load is measured through the jack, with extension recorded from an independent datum point.

Ground Anchor Testing

Proof testing is employed to demonstrate the anchor performance, prior to excavation at the front of the face. For temporary anchors, the proof load is generally 125 % of the working load. Following proof loading, anchors are locked-off at working load to provide an active restraint to the structure.