EP0758419B1 - Bodenverstärkung - Google Patents

Bodenverstärkung Download PDF

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Publication number
EP0758419B1
EP0758419B1 EP95916766A EP95916766A EP0758419B1 EP 0758419 B1 EP0758419 B1 EP 0758419B1 EP 95916766 A EP95916766 A EP 95916766A EP 95916766 A EP95916766 A EP 95916766A EP 0758419 B1 EP0758419 B1 EP 0758419B1
Authority
EP
European Patent Office
Prior art keywords
tendon
ground
support
bore
tendons
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP95916766A
Other languages
English (en)
French (fr)
Other versions
EP0758419A1 (de
Inventor
Michael John Turner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB9408697A external-priority patent/GB9408697D0/en
Priority claimed from GB9419495A external-priority patent/GB9419495D0/en
Application filed by Individual filed Critical Individual
Publication of EP0758419A1 publication Critical patent/EP0758419A1/de
Application granted granted Critical
Publication of EP0758419B1 publication Critical patent/EP0758419B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/74—Means for anchoring structural elements or bulkheads
    • E02D5/80—Ground anchors
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D17/00—Excavations; Bordering of excavations; Making embankments
    • E02D17/20—Securing of slopes or inclines

Definitions

  • the invention relates to ground supports of the kind generally known as soil nails.
  • Soil nails are inserted into unstable ground, for example at the side of a steep cutting in order to provide stability for the ground.
  • Use of soil nails allows steeper cuttings than can be employed with unsupported soil, thus allowing roads and other works to be accommodated on smaller sites than would otherwise be possible.
  • Temporary soil nails can also be used to provide stability for deep excavations with steep walls, for example in foundations for buildings.
  • a typical soil nail comprises a steel bar which is inserted into an hole bored in the ground, a space within the bore around the bar being filled with grout or a similar filler. At its outer end, the soil nail is normally connected to a surface support such as a ground plate or to steel mesh embedded in a layer of concrete.
  • a soil nail is not normally tensioned during or immediately after installation. However as the ground being supported yields, normally with a tendency to induce an axial tensile force into the soil nail, load builds up in the soil nail and it becomes effective as a support for the ground against further movement. Soil nails are typically about 3 metres to 10 metres in length.
  • An object of the present invention is to provide a ground support of the kind known as a soil nail which is effective against corrosion but does not require the conventional protective sleeve.
  • a ground support for stabilising ground by installation thereof in a bore in the ground characterised by a head member at the inner end of the support, at least one elongated flexible polymeric tendon extending longitudinally within the bore from the head member to the outer end of the bore, the tendon being embedded in a matrix of filler material and means for anchoring the end or ends of the tendon externally of the bore.
  • the tendon is in the form of a belt or strip of webbing.
  • the head member provides an anchorage for the inner end of the tendon and the tendon increases the capacity of the soil body to resist tensile forces.
  • the filler material fills the void in the bore provided during the installation and permits forces to be transmitted between the tendon and the soil body both directly and via the head member.
  • a double tendon is formed by attaching the material thereof remote from its ends to the head member to provide two tendon sections, each of which extends along the bore.
  • the filler can then help to maintain the tendon sections in desired positions in the bore.
  • the tendon is attached to the head member by passing it around the head member.
  • Preferably two double tendons are employed to provide four tendon sections extending along the bore.
  • the outer end or ends of the tendon or tendons may be attached to a surface support adjacent the entry to the bore and means such as a turn buckle may be provided for taking up slack in the tendon.
  • the filler may be a conventional grout, as used in ground anchoring, or it may be a sand and cement mix or hydraulically placed sand or a synthetic resin or pulverised fuel ash and cement mix or some other suitable material.
  • Figure 1 is a cross-section through a civil engineering site such as a road widening scheme at a position where the road is below ground level. Soil from region A has been excavated to provide new road surface B in place of the original ground surface C. The excavation leaves a near vertical bank D which if unsupported would be unstable and would cause soil to collapse on to the road surface. The soil in region E is supported by soil nails F.
  • the shotcrete is concrete which is sprayed on to the surface and is supported by steel mesh extending over the surface.
  • Figures 2 and 3 show a soil nail in accordance with the invention which may be employed for example in a civil engineering site as shown in Figure 1.
  • the soil nail is assembled into the condition shown in Figures 2 and 3 within a bore drilled or otherwise formed in the soil to be stabilised.
  • the soil nail will be described in this installed condition.
  • Each tendon is in the form of a belt or strip of webbing produced from structural fibres such as polyester or polyaramid.
  • One suitable polyaramid material is known by the trade name Kevlar.
  • Suitable webbing is known by the trade name Paraweb.
  • Each doubled over tendon extends throughout the length of a bore 13. In particular, it extends from outside the bore, round a head member constituted by a nose cone 14 at the inner end of the bore and again emerges at the outer end.
  • the individual tendons are spaced at 90° to each other as best seen in Figure 3.
  • Ties and/or spacers such as 15 are provided at intervals to retain the tendons generally near the outer periphery of the bore 13. More than two doubled tendons may be employed if required and instead of or in addition to double tendons one or more single tendons may be secured to the nose cone.
  • the structure of the nose cone 14 is not critical. It may be a plastics moulding. Alternatively it could be formed of metal or concrete or other stable material.
  • the nose cone serves as an aid to insertion of the tendons in the bore and helps to ensure that the tendons extend along the full length of the bore.
  • the tendons are typically engaged with a surface support for the soil.
  • steel mesh 16 represented in the drawing by four transverse rods is provided at the surface of the soil and the tendons are wrapped round the reinforcement rods and united by a clip 17.
  • the bore 13 is filled with a matrix 18 of grout or of a sand and cement composition or other suitable filler to embed the tendon in the filler.
  • a matrix 18 of grout or of a sand and cement composition or other suitable filler to embed the tendon in the filler. It is not necessary for the filler to be rigid, for example it could be constituted by sand which may be hydraulically placed to ensure effective compaction. This matrix surrounds the tendons so that they are intimately embedded in the surrounding soil body.
  • the nose cone embedded within the matrix acts as an anchor for the inner ends of the tendons so that tensile loads developed in the tendons by soil movements at one location are transferred into the soil elsewhere along the length of the soil nail both by friction between the tendons and the matrix and by compression in the matrix at the location of the end anchorage. These loads are transferred in turn into the soil by friction between the matrix and the surrounding soil.
  • the outer surface of the soil including the reinforcement 16 and the outer ends of the tendons is embedded in material 19 known as shotcrete, that is sprayed on concrete.
  • a typical soil nail of this kind is from 3-10 metres in length in a bore of about 75mm diameter.
  • Each tendon typically has a tensile strength of about 50kN, providing a tensile strength of about 200kN for a soil nail with two doubled over tendons.
  • tension tends to develop in the soil nail as the soil within which it is installed begins to yield due to release of the horizontal confining pressure previously provided by soil A.
  • the tensions in the tendons within the soil nails support the soil in region E to prevent collapse of the soil behind the bank D.
  • the soil may be allowed to collapse around the tendon or tendons such that the soil comes into intimate direct contact with the tendons to embed tendons in the soil and tensile load develops in the tendons due to shear effect between the soil and the tendons.
  • the tendons may be driven into the ground by a rod which forms the bore at the same time as inserting the tendons.
  • the ground support shown in Figure 4 incorporates tendons 11 in a bore 13 and corresponds generally to the arrangement of Figure 2. Any variations, other than those specifically described, are self evident and coincidental.
  • the shotcrete is applied in two separate layers 31 and 32.
  • a load transfer assembly 33 is applied against the face of the shotcrete at the entry to the bore 13.
  • the load transfer assembly incorporates a plate 34 which engages against the face of the shotcrete and through which the tendons 11 pass.
  • the load transfer assembly also incorporates turn buckles 35 supported in seats 36. End portions of the tendons 11 are passed through the turn buckles 35 which are arranged such that slack can be taken up in the tendon by rotating the turn buckle, for example by means of a tommy bar.
  • the turn buckle is locked off, for example by means of a pin passing through the turn buckle and the seat 36.
  • the second layer 32 of shotcrete is then applied.
  • a complete support system may be made up of several support installations as shown in Figure 4, arranged at suitable spacing.
  • Figure 5 shows diagrammatically a support system with an alternative tensioning means.
  • a grid of soil nails 41 conforms generally to Figure 2.
  • a netting of structural plastics material or a grid of steel reinforcement rods may be applied to the exposed surface of the area being stabilised as illustrated at 42.
  • the preliminary layer of shotcrete 31 as shown in Figure 4 may also be applied or reliance may be placed on the grid 42 itself at this stage.
  • tendons 11 For taking up slack in the tendons 11, instead of relying on the turn buckle arrangement as shown in Figure 4, adjacent tendons are connected together through adjustable connectors 43 for taking up slack.
  • the outer parts of the tendons thus form a support for the surface of the area being stabilised.
  • the tendons 11 are both connected to the connectors 43 and are then tightened and locked in the tightened condition by operation of the connector.
  • the tendons are prevented from pulling sideways out of the borehole by means of a retaining ring device 44 at the head of each nail.
  • Any suitable form of connector may be employed, possibly employing a turn buckle as illustrated in Figure 4 or possibly being constituted by some other kind of tensioning and locking device.
  • the tendon may be terminated as shown in Figure 4 or by connecting it to a grid or by pinning the connecting turn buckle device to the ground surface by using a driven steel pin, or in any suitable way.
  • This technique is suitable for environmental designs, where vegetation can be encouraged to grow through the retaining grids and meshes, so that the supported slope rapidly takes on a natural appearance. If required, however, shotcrete, possibly incorporating some further stabilising mesh can also be applied to the surface, to protect the tendons and prevent erosion.
  • tension builds up immediately on occurrence of any slip in the soil being stabilised whereas without some pre-tension, significant movement may occur at or near the surface before tension builds up.

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  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Mining & Mineral Resources (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Paleontology (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Piles And Underground Anchors (AREA)

Claims (12)

  1. Bodenstütze zum Stabilisieren des Bodens durch ihren Einbau in eine Bohrung (13) im Boden, gekennzeichnet durch ein Kopfteil (14) am inneren Ende der Stütze, mindestens eine längliche flexible polymere Sehne (11, 12), die sich in der Bohrung (13) von dem Kopfteil (14) zum äußeren Ende der Bohrung (13) in Längsrichtung erstreckt, wobei die Sehne (11, 12) in eine Matrix (18) aus Füllmaterial eingebettet ist, und eine Einrichtung (17; 35; 43) zum Verankern des Endes oder der Enden der Sehne (11, 12) außerhalb der Bohrung (13).
  2. Bodenstütze nach Anspruch 1, dadurch gekennzeichnet, daß die flexible polymere Sehne (11, 12) in Form eines Gewebegurts oder -bands ist.
  3. Bodenstütze nach Anspruch 1 oder Anspruch 2, dadurch gekennzeichnet, daß die Stütze eine doppelte Sehne (11, 12) aufweist, die durch Befestigen ihres Materials fern von ihren Enden an dem Kopfteil (14) gebildet ist, um zwei Sehnenabschnitte (11, 12) zu schaffen, von denen sich jeder längs der Bohrung (13) erstreckt.
  4. Bodenstütze nach Anspruch 3, dadurch gekennzeichnet, daß die Sehne (11, 12) an dem Kopfteil (14) durch Herumführen um das Kopfteil (14) befestigt ist.
  5. Bodenstütze nach Anspruch 4, dadurch gekennzeichnet, daß mindestens zwei doppelte Sehnen (11, 12) verwendet werden, um mindestens vier Sehnenabschnitte zu schaffen, die sich längs der Bohrung (13) erstrecken.
  6. Bodenstütze nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Füllstoff aus Mörtel oder durch eine Sand- und Zementmischung oder durch verdichteten Sand oder durch ein Kunstharz oder durch eine pulverisierte Brennstoffasche- und Zementmischung gebildet ist.
  7. Bodenstütze nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß das äußere Ende oder die äußeren Enden der Sehne oder Sehnen (11, 12) außerhalb der Bohrung (13) durch Befestigung an einer Oberflächenabstützung (16, 19; 34) angrenzend an den Eingang zu der Bohrung (13) verankert sind.
  8. Bodenstütze nach Anspruch 7, dadurch gekennzeichnet, daß die Oberflächenabstützung (34) eine Einrichtung (35) zum Spannen der Sehne (11, 12) enthält.
  9. Bodenstütze nach Anspruch 8, dadurch gekennzeichnet, daß die Einrichtung (35) zum Spannen ein Spannschloß ist.
  10. Bodenstütze nach Anspruch 9, dadurch gekennzeichnet, daß das Spannschloß (35) auf der Bodenabstützung (34) angebracht ist.
  11. Bodenstützeneinbau mit Bodenstützen gemäß irgend einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß die Sehnen (11, 12) von benachbarten Bodenstützen durch Untereinanderverbinden der äußeren Enden der Sehnen (11, 12) von einer Bodenstütze mit den äußeren Enden der Sehnen (11, 12) von angrenzenden Bodenstützen verankert sind, um eine Abstützung für die Oberfläche des zu stabilisierenden Bereichs zu bilden.
  12. Bodenstützeneinbau nach Anspruch 11, dadurch gekennzeichnet, daß einstellbare Verbinder (43) zum Spannen vorgesehen sind.
EP95916766A 1994-04-30 1995-04-26 Bodenverstärkung Expired - Lifetime EP0758419B1 (de)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
GB9408697A GB9408697D0 (en) 1994-04-30 1994-04-30 Ground support
GB9408697 1994-04-30
GB9419495A GB9419495D0 (en) 1994-09-28 1994-09-28 Ground support
GB9419495 1994-09-28
PCT/GB1995/000943 WO1995030057A1 (en) 1994-04-30 1995-04-26 Ground support

Publications (2)

Publication Number Publication Date
EP0758419A1 EP0758419A1 (de) 1997-02-19
EP0758419B1 true EP0758419B1 (de) 1999-07-14

Family

ID=26304807

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95916766A Expired - Lifetime EP0758419B1 (de) 1994-04-30 1995-04-26 Bodenverstärkung

Country Status (4)

Country Link
EP (1) EP0758419B1 (de)
AU (1) AU2313795A (de)
DE (1) DE69510789T2 (de)
WO (1) WO1995030057A1 (de)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0079880B1 (de) * 1979-04-04 1986-09-17 Gerhard Dipl.-Ing. Dr. Schwarz Stützbauwerk
US4324022A (en) * 1980-06-16 1982-04-13 Ancra Corporation Ratchet buckle having reinforcement strengthening means
GR78036B (de) * 1981-07-10 1984-09-26 Henri Vidal

Also Published As

Publication number Publication date
EP0758419A1 (de) 1997-02-19
DE69510789D1 (de) 1999-08-19
DE69510789T2 (de) 1999-12-02
AU2313795A (en) 1995-11-29
WO1995030057A1 (en) 1995-11-09

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