Equipment and Techniques -Anchor Placement


The Dmm Eco Anchor & Resifix 3 Plus

(Info Supplied by CNCC Technical Group)

The Anchor

The Eco anchor is produced by DMM, in 8mm diameter 316 stainless steel, (which is also used for marine applications). It is then formed into a double 'P' shape, which requires a drilled hole of 18mm x l00mm deep.

Wear & Tear on the Anchor

Being made from 316 stainless steel there should be very little wear even on anchors placed on popular pull through routes. Anchors placed in Swinstow Hole Yorkshire, show very little signs of wear on their inner curvatures. Should an anchor fail the annual test, then it should be deemed unsafe and a regional official should be informed. The regional anchor officer/co-ordinator shall ensure that the anchor is checked, and if necessary, another anchor will be installed into the hole. Although the Eco anchor has considerable strength, basic rigging practices should still be observed i.e. back ups & 'Y' hangs etc.

The Chemical Anchor Mortar

The resin that shall be used to secure the Eco anchor shall be RESIFIX 3 PLUS chemical anchor mortar. This can be used in dry or wet conditions. A limitation is that it cannot be used when the temperature on the day of application is below -5'C. The resin is contained in a large tube, this large tube contains the polyester resin and a smaller tube, the smaller tube contains the activator. Both are expelled simultaneously and mixing occurs in the nozzle. As the resin and activator pass through the nozzle and mix, a colour change takes place. When the colour is consistent (no streaks), the mortar is correctly mixed, and can then be injected into the hole.

If an open tube is not used for some time, or curing has taken place between pitches, remove the nozzle, then remove any hardened mortar from the two apertures in the end of the tube. Screw on a new nozzle and expel the chemical mortar until a consistent colour is achieved.

Warning

Avoid breathing the vapours and skin contact, wear gloves and goggles when injecting the resin, ensure that you read & understand the precautions supplied which each tube of chemical anchor mortar.

Curing time, this varies with temperature, underground at +10'C. Curing is complete within 80 minutes, this however may be longer or even shorter. Therefore, a minimum of 6 hours must elapse before the anchor is loaded.

The chemical anchor mortar is flammable, keep cartridges Away from naked flames & out of direct sunlight. The use of Carbide lamps is not recommended when using the mortar. In the event of fire use a dry extinguisher.

It is recommended that TWO people, experienced in rigging, discuss the following points before fixing the anchors:

  1. Anchor sites to be suitable for SRT, laddering or pull through trips.
  2. TWO resin anchors for:
    1. Main belays for abseil and S.R.T
    2. Re-belays if more than 10 metres from the pitch bottom, or next re-belay.
  3. Anchors should give a free hang, check for rope rub by holding krab or maillon just clear of the wall with rope attached. Consider methods of linking anchors; see Figs. 4 & 5.
  4. Anchors need to be reasonably high; this allows the main belay knot, shared anchors, traverse lines, and attachment for belay device or pulley to be shoulder high. This will decrease fall factors for any one fastened on, facilitate SRT rescue and access to and from the head of the pitch.
  5. Resin anchors need to be at least 20cm (8 inches) apart to, avoid overlapping stress cones in the rock. The anchors should be angled towards the proposed direction of loading figs. 3,4,5 & 6.
  6. Pull through routes, two anchors should be available for pitches in excess of 4 metres. The hangers can either share the load or be super-imposed; either method is acceptable fig. 6. If using the super-imposed siting, fig 6b, then careful alignment and angle of anchors will ensure a trouble free rope run, for retrieval after abseil.
  7. Existing 8mm S.D. anchors can be left in if they do not compromise the optimum siting and are not to close to the resin anchors. If the old 8mm S.D. anchors are within 150mm (6 inches) of a resin anchor they are best removed, the hole can be enlarged to take the resin anchor.