THE PRODUCT

FS  PERMANENT SOIL
ANCHOR  SYSTEM  REGROUTABLE

Foundation Specialists [FS] has a long and successful experience in the installation, post tensioning and testing of permanent soil anchors and temporary soilanchors.

            FS has installed permanent soil anchors and rock anchors,  post tensioned soilanchors and post tensioned rockanchors   in  various Countries for  a large spectrum of  structures and purposes : in the Philippines FS has successfully installed soil anchors and rock anchors all over the country, for a variety of projects, post tensioned soilanchors and rockanchors for Power Plants, post tensioned soilanchors and rock anchors for Dams,  post tensioned soil anchors and rock anchors for Steel Mills, post tensiones soilanchors and rockanchors for the perimeter walls of Building Basements, post tensioned soil anchors and rock anchors for the foundation of tall slender buildings. Foundation Specialists has also installed post tensioned soilanchors and rock anchors for Slope Support.  For slope protection and support FS also installs drilled and grouted Soil Nails and displacement Soil Nail. Foundation Specialists has installed and tested post tensioned soil anchors and rock anchors for Anchor Blocks for anchoring of inclined Penstocks, liquefied gas pipelines on slopes, very tall transmission towers. FS has installed post tensioned soilanchprs and rockanchors for Bridges and Viaducts, post tensioned soil anchors and rock anchors for  Road Tunnels,  post tensioned soilanchors and rockanchors for River  Diversion Tunnels , post tensioned soil anchors and rock anchors for Diaphragm Walls, post tensioned soilanchors and rockanchors for retaining walls, post tensioned soil anchors and rock anchors for Anchored Pile Walls, among others.

Foundation Specialists   has  installed long post tensioned soil anchors  in historical Luneta (MANILA) for the anchoring  against  uplift forces, of the National Museum  vast  underground  reinforced concrete water reservoir.

In particular in the Summer Capital of the Philippines, Baguio City, FS has,  as far as 1987 (twenty years ago) ,  installed permanent groundanchors, post tensioned soilanchors  ( regroutable ) on a sub-vertical slope, for a composite diaphragm wall designed to save, from collapse due to heavy scouring,  the  Citicorp rest-house complex  built  on top of the Mine-view slopes. [Interesting to note that the Citicorp complex subsequently survived without damage the 1990 earthquake, while several neighbouring structures   collapsed or were severely damaged].

Also in the Baguio area, Foundation Specialists has installed   permanent soil anchors and permanent rock anchors to support the abutment structures  of the Camp 5 bridge along Kennon  Road, among others.

The Permanent Ground Anchors permanent soil anchors and permanent rock anchors  installed by FS are done  in accordance with  ASTM, European and British Standards. In addition to it, to cope with the difficulties created in tropical regions  by having to deal with residual soil formations, Foundation Specialists has introduced  an additional feature that makes the permanent soil anchors installed by FS ,   pressure-groutable and regroutable soilanchors and rockanchors.

DESCRIPTION OF 
FS PERMANENT GROUND ANCHOR REGROUTABLE

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FS PERMANENT GROUND ANCHORS "REGROUTABLE" are assembled using high strength steel strands complying  with ASTM standards A416-87a Grade 270.  The bonded length of the strands is accurately cleaned from grease and lubricants to assure a perfect bond with the cement grout.  on the other hand, the free stressing length of the strand is kept with the original  grease.  The Permanent Casings are made of  HDPE (heavy duty poly-ethylene, the “manchette” pipes used for grouting are made of  PVC.  Likewise the spacers used for the strands and the  centralizers  employed for the  main assembly are made of PVC .

 The individual protection  of the free stressing steel strands (passive anchor length) is made with grease filled  individual HDPE tubes.

The corrugated permanent casing is closed at the anchor bottom end by a watertight cap , while the top end of the corrugated HDPE casing is  inserted into a watertight , sealed and grease-filled assembly, which contains the head steel anchor plate, the anchorages, and the anchor head cap.

All material employed  comes with mill certificate.

              PROCEDURES FOR
         ANCHOR INSTALLATION  and  GROUTING

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 Once the hole for the anchor has been readied, the anchor assembly is installed into it, for  the entire length of the permanent casing, then grouting begins, from the bottom up, using a non corrosive  shrink-compensating  cement grout.  Both  the inner and the outer space  of the anchor assembly are backfill-grouted.    For the cement grout, care has to be taken to keep  the water-cement ratio at a minimum, to avoid  to generate bleeding  while  curing.    The cement grout injected inside the permanent casing  provides the necessary bond between the active strands length  and the corrugated HDPE casing, while the cement grout injected outside the corrugated HDPE casing, to fill the drilled anchor hole, provides the bond between the anchor assembly and the surrounding  ground.

            The  ground anchor , as described here above, is a standard Permanent Ground Anchor.  Both the bond between the steel strands and the  casing and  the bond between the casing and the  surrounding ground  are provided by the  backfill grout as described. The reliability of the system hinges on the efficiency of the shrink compensating grout 

additives, which are expected to avoid the formation of a gap at the two interfaces upon completion of grout curing (that usually involves shrinkage ).

It is not uncommon to observe anchors  that, when being tensioned,  are sliding  slowly forward, thus losing tension:  when this happens, the anchor has to be pulled out and  the job done again.

The fact that some anchors become lose, it is caused sometime by defective grouting procedures, but most often is due to  the characteristics of    the surrounding ground formations.

To obviate these problems, FS ha introduced  implements and procedures such that, with no change to the final characteristics and properties that make the Anchor  a "PERMANENT ANCHOR”,  enable the Contractor to further re-grout the Anchors, under  increasing pressure.  High pressure injections carried away through manchettes greatly improve the efficiency and reliability of the bond between the anchor assemly and the surrounding soil strata  by compressing the ground around the anchor by means of pressure injected  cement grout (thus the definition of  REGROUTABLE) .

 The same principle is applied for the inner part of the permanent casing.

The free stressing length of the soil anchor is organized in such a way that while the space between the protective HDPE individual  tubing  is eventually grouted to prevent accumulation of water or moisture, the strands , inside their individual  greased tubing, remain permanently free to stretch (during earthquake), as designed.

At the end of each grouting stage the manchette pipes are washed and cleaned and remain available for further grouting stages, if ever the need  for  it would arise.

The  grout  injections are carried out  through  manchettes  (one way valves usually inserted at 50 centimeter intervals  on the grout pipes) and  flexible double packers  properly designed for the purpose.