CA2038374C - Fixing means for connecting components - Google Patents

Abstract

Fixing means for connecting components, particularly prefabricated concrete members and tubbing stones, consist of pluglike anchors, which are adapted to be forced with elastic deformation into anchor holes, which are formed in said components and open to the joint between said components. As a result, the anchors are frictionally held in and/or positively locked in the anchor holes. The anchors are substantially stiff and have a peripheral surface which at least in portions intended for a rataining engagement with the inside surface of the anchor hole is designed to be elastically deformable at least in an approximately radial direction and at least in said portions consists of a plastic material, which has entropy elasticity, or of wood, which is so arranged that its fibers extend in the longitudinal direction of the anchor.

Description

~1338~

~I~{ING ~YIEANS ~O~ CONNEC~ING COM:PON~NTS

BACK~EIOIJND O~ ~3 INVENTION

Field o~ the Invention Thi~ invention relate3 to fixing me3~ or connecting component~, particularly prefabricated concrete member~ or tubbing ~tone~ 9 w~lich means comprise a plurality of pluglike anchor~ 9 which are adapted to be forced with ela~tic deformatio~ into arlchor hole3, w~ich are i~ormed in ~aid co~nponsnt3 a~d open in confronting sur~ace~ o~ ~aid component ~, ~o that the ~lChOr8 ar0 frictionally held in and/or po~itively locked in the anchor holes.

De~cription o~ the Prior Art ~ ixi~ me~ of that kind are u~ed, e.g9, in the co~Ytruction of tunrlel 1 ;n;n,g~ to COl:lrLeC~ the ~ubbing ~tone~ or other ri~g eleme~$~, a~d may ~u~titu~e conventional ~crew Ia~tener3, which are expen~i~e and ca be used only with dif~iculty and i~volYe a wepken; r~g o~
the material. ~he anchors may be mount~d be~ore a ~e~v ~tone i3 in~tall~d 90 that the a~chor~ may be usad al~o to align an additior~al component with previously placed components ~o that a modular as~ambly o~ the component~
ca~ be obtained~ Other ~ield~ o~ applica~ion o~ fixing means o~ the preoent kind are joints between relatively large structural component~, ~uch as pre~abricated concrete elements, in bl~i 1 (li n~ construction and civil ~ng1 neering.

From EP-A-100 771 it i~ knoml to COIlrleGt tubbing stone~ by mealls o~ sleevelike li~er~, which are in~erted into anchor holes and made o~ rubber-ela~tic or ot}ler ela~tically deformable material and havs holes ~3~37~
Z

which flare conically near and toward the outer end o~
the ~leeve but are cylindrical elsewhere. Anchor~ are employed which con~ist of cylindrical metal rod3, which have pointed en~ and are ~ir~t drive~ i~to the anchor hole~ of one stone and a~ the stones are engaged with each other are in~erted into the li~er~ o~ the prsviously placed stone~ The in~ide diameter of the cylindrical holes o~ the liner~ iY smaller than the out~ide diameter of the mstal rod~ so that said metal rod~ are in~erted into the liners with ela~tic de~ormation and are ~rictionally retained therein. ~he slastic deformability of the ~leevelike li~ers i3 inte~ded to ef~ec~ a correction o~ any mi~ nment of the axe~ o~ the metal rod~ and the axe~ of the a~sociated anchor hole~, D~-A-22 38 792 provide~ for connecting platelike 3egment8 by fixing mean~ ~hich co~si~t of ~leeves~ which are in~erted into one compbne~t~
and anchor bolt~, ~hich are fixed to the other c~o~ponent.
Spring tongues are secured to the sleeve and ~L G~ 4Q ~
from the open free end o~ the ~leeve . 5aid ~pri~ tsngu~s are d~flected and clamp the bolt a~ it i~ scrtad - i~bo the ~leeve 80 that a frictional con~aot i~ achi~ed.
EP-A-114 514 disclo~e~ ~imilar fixing mean~ for co~-necting tubbing stones.

D~ A-24 57 427 discloses fixing meaIl~ which are of the kind de~cribed first hereinbe~ore a~d comprise an a~chor consi~ting o~ a steel bolt havi~g in cros~-sectioll a sawtoothlike external ~hape bu~
uniform crest ~d root diameter~. ~hat steol bolt is adapted to be forced into a liner~ ~Nhich has bea~

(3 3 7 l~

insert~d into the anchor hole and is made o~ rubber-elastic material and has on th2 out~ide a mating or corrugated shape in cros~-~ection.

All _~ewn fixing mean~ of the pre~ent kind have the disadvantage that ~eparats liners made, e.g., of rubber-ela~tic material mu~ be inserted into the a~chor holes in mo~t ca~es ~o that the ma~u~acture o~
the component3 i~ dif~icult. If the anchor a~d the liner in the anchor hole have corre~pon~in~ shapes in cross-sectio~, the re~tr~;n;ng ~orce wqll not bP
~uffic~ently large and ~rom the beginnin~ o~ the insertion of the anchor into the liner it is necessary to overcome the re~istance of the li~er to deformation until the anchor has been i~erted as ~ar as i9 required.
I~ somc design3 that resi~ta~ce to deformation progre~D
sively increases as that i~3ertio~ proceed~. ~articul~rly at the beginn; ng of the in~ertion the anchor will be ~ubjected to a high bl~ckling load and thi~ mu~t be taken into account in the selection o~ ths cros~ ~ectio~al areas. Whsre ~ixing mea~8 which establi~h only a re~tr~.~ ni ng frictional engagament are amploysd, ~he driving forces required and the restr~in;ne force~
will not axactly be dafined owing to the mQnu~acturing tolerance30 Similar remark~ are applicable ~or a fi~atio~
by means o~ deflectable 3prin~ tongue~.

Summar~ o~ the Invention It is an obàect o~ the invention to provide fixing means which are o~ the kind described ~ir~t hereinbefore and are simple in de~ign and particularly have simple anchor holes and ~er~it ~trong and de~inable restr~i n; ng force~ to be exerted on the anchors~

'~3~,~7l~

lt is another ~oject of the invention to prcvide ~i~ino ~e2ns in l~hich th~ 2nchnrs can be more easily be inserted inta the anchor holes anri the forces requirod t3 overcame the resistanc2 to deformation need to be ~xErted only durin~ _ fractional oart oF the disolace-ment of each anchor as it a inserted, ond which ensure that each anchor will reliably reach the required position in the anchor hole 50 -that, e.n., sealinn inserts provide~
between tha comoonents to 'e connecteo will reliably be subjected to the reouired initial stress.

The first object stated hereinbefore is accomolished in that the anchors are substantially stiff and have a oerioheral surface which at least in oortions intended for a retaining engaqement with the inside surface o~ the anchor hole is ~esi~ned to be elastically deformable at least in an apDroximately radial direction.

The basic concept cf the invention resides in that the elastically deformable means which are required to exert the restraining forces are provided on the anchor and the anchor is designed to have in its axial direction a suFficiently hioh stiffness so that the anchor can be inserted without diFficulty into the associated anchor hole.

The peripheral surFace of the anchor may con-sist oF a plastic material which has entropy elasticity.

~ winq to the use of a plastic material which has entropy elasticity the insertion of the anchor is racilitated and the retaining force exerted by and on the anchor which has been inserted is in-creased. The term entropy el3sticity describes a fluw behavior which is exhibited by plastics when aFter an ~lastic deformation they tend ';o assume their initial 2~3~

shaoe bv creYn ~o~e~ents or when under the action oF
actual oressure fnrces the\! tenrl to ~low into regiDnS
which are under a lower pressure load at that ti~e so that the oontact pres~ure forcrs will suostantially be euqalized when the flow orocess has terminated. In the oresent c3se that Flow beha~ior ran be u-tilized in that the deformable Peripheral oortions of the anchor are somoressed by ~eans of separate aODaratUseS or in constricted portions of t~e anchor holes and/or to displace said deformable oortions in the lanoitudinal ~irection of the anchor. I~lhen the anchor has been inserted into -the anchor hole to the required extent, portions of the elasticallv defor~ed zones will flow into recesses formed in the inside surfaces of the anchor hole so that a positive and frictional anchorino will be o~tained. ~ substantial anchoring action will be achieved even in anchor holes havinq a rouoh inside surface of concrete if, in the simplest case, sub~
stantially cylindrical anchor holes are orovided as well as corresponding anchors which have elastically deformable zones which are larger in diameter than the adjacent zones of the holes. The anchoring action can substantially be increased by further measures, e.g., by the provision of undercuts in the inside surface af the anchor hole.

Surprisingly it has been found that a se-lection of proper materials will permit satisfactory re-sults to be produced even if the oeripheral surface of the anchor consists of wood, particularly of soft wood, if that wood is so arranged that its fibers extend sub-stantially in the longitudinal direction of the anchor.
Fir and spruce are preferably emoloyed as soft woods, which have a much hioher sitffness in the longitudinal direction of the fibers and have a hioh modulus of ~3~3 ~

elasticitv ~;ransversely to t~le ~irection of the lbers so that their retaininn oraoerties are similar to those af the above-~entiorlod alastic ~aterial. T~e entire anchor ~ay consist nf a l)oo~en aart in l~nich the Fibers extend in the lonnitudinal direction 5f the anchor and l~hich has been i~nreanated to rasist an inoress nf ~oisture and outrefaction. The wooden oart may be made in one oiece or may consist of a oluralit\/ of element.s "~Ihich have been 'oined e.n. with olue and have then been oiven their final shape. Reinforce~ents and inserts such as will be mentioned hereinafter ~ay be nrovided also in a wooden part.

In a preferred embo~iment each anchor is formed in that portion ~.~hich is to be inserted into one of the anchor holes with two or more retaining zones for enoaging the i.nsirle surface of the anchor hole. It will oe particularly desirable if the average diameters of the retaining zones of the anchors and of the anchor holes consecutively increase from one retaining zone.
It l~ill be particularly desirable if the average dia-meters of the retainino zones of the anchors and o the anchor holes cnnsecutively increase from one retaining zone to the next in the direction extending away frorn the inner end of the anchor and anchor hole.

2~3~3~

Tha provision of stepped anchors and anchor hole~ has the reRult that the deforming ~orce to be exerted for a frictional and/or po3itive restr~ining engagement wqll have to be exertsd only in the region in which a sociated re~trainin~ zone~ of the anchor or anchor hole engage each other, i.e~ only toward ths termination of the insertion of the anchor into the anchor hole and duri~g a correspon~; n~ fraction~l part of the di~placement by which the anchor i9 in~erted into the ~chor hole and it will ba nece~ary to e~:ert that force o~ly when the ~chor i~ already s~icien~ly guided in the anohor holeO ~hat g~ ce will be improYed by the f~ct that buckling load~ on the ~nchor will substa~tially be avoidsd in all retaini ng zc~ne8 a~ld excessive loads will be avoided ~v~n ~ha~ the anchor and tha anchor hole are ~ot exactly ~ ned duri~g the a~emblin~ operationO On the contrary, the anchor will strictly act a~ a g~Aiding element during a major part of the displacsment by which the anchor hole i8 inserted into the a~sociated ~chor holeO

Within the ba~ic desig~ provided in accordaac~
with the invention, various ~ariation~ in detail mag be adopted. In a pre~srred embodiment the reta;n;ng zone~
of the anchor are ba~ically cylindrical or have a ~lender conical ~hape increasing in thi ckne~8 to~ard the end o~
the a~chor that i~ to be inserted into the ~nchor hole.
Oonical transition portions may be provided bet~en thc ret~ining zonss. The 31ender conical shape which increaqe~ in thickne~ toward the free end o~ th~
anchor ~ill improve t~e retention oi the a~chor in the anchor hole.

~3~3~7~

An em~odiment may be adopted in ~hich the anchor i~ provided in the ret~inin~ zones with Annl~le~
pads ~ich are made of a material which i~ more ea~ily de~ormable and has a higher coefficient of ~riction than the remaining ~nchor material~

- In accordance with a further preferred feature the ~nnl]l~ pad~ are inserted in ~nnl~l er groove~ which are provided on the peripheral ~urface o~ the anchor and have in axial 3ection a sawtooth ~hape having sloping tooth ~ide faces ri~ing toward the i~ner end o~ tha anchor. When a force ten~i n~ to pull the anchor out o~ the anchor hole i~ exerted on the a~chor, ~aid ~loping ~ide ~ace3 will tend to ef~ec~ an exp~nAing deformation of the pad, which ha~ a~ out~ia~ sur~ace in contact with the inside ~ur~ace o~ the allchor hole3 ~o that the contact presflure exerted by the pad o~ th~-surface o~ the hole and the sd~e~i~re force will be increa~ed .

In a different embodiment~ comh~ nnnl ~r~
pro jection~ are provided i~ ~8ch rete;n;n~ zolle~- o~ he::
anchor hole and a~ leasl; on that side which faces :ths;
inner end o~ the anchor hole de~i~e uIldercut~ a~d ha~e an in~ide diameter that i~ sm~ller tha~ the out~ide diauneter of the a~chor in the a~sociated ~one. That design may be adopted for u~e with an anchor wh~ch ca~ be elastically deformed at lea3t in part and will have the result that u~en a ret~nine zon.e o~
the a~chor has been f'orced past the annular projection the matarial of that zone will flow into ths u~dercu~
~o that the anchoring will be imprcvcd~, ~he pro~ection~
in the anchor hole may c0~9i~t 0~ annular in~ert~ of metal which are held in ths concreteO ~n order to 2~3~3~

_ 9 increa3a the size of the undercuts providsd behind ~aid armular inserts? ela~tically deformable or detachable in~erts may be proYided un ths x ear o~ the rings be*ore the concrete i9 ca9t .

In a ~urther embodiment the anchor~ are made of pla~tic and provided wit;h a metal rein~oroement. ~he a~chors ca~ speci~ically be made OI polyamide, polye~h-ylene and polypropylexle a~d the rein~orcement~ ~re:~erably consist of iron or ~teel. Alter~atively~ me~h rein~orce ments may be provided or the core8 of the ~chor~ may be made o~ plastic reinforced with glass ~lber~. The distribution o~ the total stress to the plasl;ie a~d reini~orcement will be detiermined in ~riew o~ the severity o~ the u~age ~ the required li~e arLd the requirsd strength ., pre~erred embodimen~ the reini~orce~e~t co~ist~ o~ a lo~gitl~;n~l tubet which is embedded in the pla~ti¢ and which is provided on the outside with ret~in;ng ring~
which are embedded i~ the plastic material at the ends of e~ch retai ni ng zoneO I~ that ca~e the plastic mater~al will be backed by a ring adjacent to aach retQ; n; ~ zone ~o that the de~ormi~g forc~s t~ be exerted for the ~ixation a~d ths ret~ining foroe~
e~erted by and o~ the in~talled anchor will be applied in a d2sirabl~ r~nner.

~ he as~embling may b~ facilita~ed in that each anchor ha~ conically tapered end portion~ and each a~chor hole may conically flare from the con~ronting ~urface~ of the component~ to the neare~t retai n; ng zone 0~ the anchor hole.

Further details and advan~age~ o~ the inve~tio~
will become apparent from the sub~equent de~¢ription o~
the drawing.

2~3~37~

Brief Description o~ the Drawin~

Figure 1 is a fragmentary ~ectional ViQW
~howing a portion of a concrete member formed with an anchor hole together with an aachor which ha~ one half that ha~ been inserted into ~aid hole and another half intended to be ~ecured to another concrete m~mber~
Two different anehor embodiment~ are ~hown in the two halves of Figure 1.

Figure 2 is an enlarged axial sectional vie~
~howing as a detail a retaining portio~ o~ the anchor.

~ igure 3 iY a view which correspond~ to th~
left-hand half of ~igure 1 a~d show~ a diff2re~t ~i~in~
device.

Figure 4 i9 a fragmentary sectional view showing the anchor of the fixi~g deviae o~ Figure 3 in an undeformed 3tate.

Figure 5 is a view which also oorre~p~nd~
to the left-hand half of Figure 1 ~d ~how~ a fu~her:
fixing device.

Detailed Description o~ the Preferred ~mbodime~

The invention i9 illustrated by way of example o~ the drawings.

In accordance with Figure~ 1 and 2, two concrete member~ which are to be conncctQd and eo~i~t, e.g., of tubbi~g stones a~sociated with r~peatlve ri~g~
are formed on con~ronting end ~ace~ 1 with 3pace~ ~part ~ ~ 3 ~?~

a~chor holes 2~ In the illustra~2d embodiment~ each of 3aid a~chor holes compri~e~ three longit~ n~lly ~ nedt cylindrical retai ni n~ zons~ 3J 4~ 5 9 which increa~e in diameter from the bottom 6 of the hole 2 toward the end face 1. A cQnical flaring portion 7 i~ provided in the hole 2 between the outermo~t retaining zone 5 and the end face 1.

A plllgl i ke a~chor 8 comprise~ two arlchor heads 10, 11, which e~ctel~d from a tubular intermediate member 9 and are normally iden~ical. ~ach a~chor head 10, 11 ha~ a conica1 end portion 12 and has retQining zones 13~ 14, 15 Yvhich are axiallg arrar~ed like the ret~inin~ zone~ 3, 49 5 of the a~chor hole 2.
A3 is particularly apparerlt ~rom Figure 2 t:be a~chor 8 i~ provided adjacent to each o~ the ret~.;n~ng zons~ 13 to 15 with ~nnl~l~r pads 16~, ~ich cox~i~t o~ a matarial that has a high coefficis~t of friction a~d is mor9 easily de~ormable than the rem~inin~ material. o~ the anehor. Said ~nn~ pad~ extend in ~nn~ r groova~
formed on the periphery of the anchor~ ~I!he bottom o~
ea~h of ~aid groove~ ha~ a multitooth sa~tooth pro~ile 17 in axial 9ect:~0n. ~he slopi~g ~id~ ~ace~ o~ ~aid teeth rise toward the inn~r end o~ the anchor 90 tha~ a pl~ ng force exerted orl the anchor head 10 arld ten~?1ng to pull it out of th~ anehor hole ~ will cau~e the loping to~th ~ide ~aoes 17 to force radially outwardly the ma~erial 16 w~ich is ir~ frictional contact with the in~ide ~urfaea o~
the ancho~ hole whereby the corltact pre~ure applied to the in~ide ~ aee of the hole will be inerea~ed i~ ea~h of the engaging zone ~ 3, 4, alld 5 .

In the embod~ment shown on the ls~t in ~ig~e 1 a major part o~ the a~chor head 10 con~:Lste o~ plastle and is provided with a rein~orcing insert consi~ting o~ a perforate~ tube 18.

In the embodim0nt ~hown on the right in Figurc 1 the anchor comprise~ an i~ner tu~e 199 which carrie~ ret~inin~ ring~ 20, 21, 22, 23 adjacent ~o the ends of the retaining zone~ 13, 14 and 15. Said retaining rings 20, 21, 22~ 23 are embedded in the plastic material 24 which con~titutes the ~hell of an an~hor.

In the embodiment shown in Figure~ 3 and 4 the anchor hole 2~ i~ al~o ~ormed with con~cutive ret~.inin~ zone~ 3a9 4a, 5a and the anchor head 10a of the anchor 9at 1Oa i~ alYo provided with retain; n~
zones 13a~ 14a, 15a, which dif~er in diameter. ~he body of the anchor 9a, 10a consi~t~ of a plastic material which is ela3tical1y daformabls to a limited e~ L:
and whioh is optionally rei~forc2d by gla~ fiber~.
Within the length o~ each o~ the ret~jning zo~c~3a~
4a ~nd 5a of t~e anchor hole 2a, conce~tric ring~ 24, 25 and 26 are ins~rted i~to the in~ide ~urfac~ of the anchor hole ~d each of 9aia riYlg~ has a~ inner~r~
v~hich i~ ~maller in di~ter tha~ tha out~ide diam~-*er:
of the a~ociated retai n; ng zone 1 3a, 1 4a or 1 5a of the arlchor. On that ~ide of each of th~ rings 24, 25 ,, 26 which is n~arer to the outer end of t:hs ~chor hol~ 2a9 the inside sur~'ace o~ the anchor hole 2a i9 ~ormed ~rith an :Inm7- ~r ra~p ~urface 27. Said insido ~urIace o~ the a~chor hole 2a i~ ~ormed o~ the opposite side oi~: each ring 24b, 25b and 26b with an ~ular surfac~ 28, which is radially o~ dly of~set Irom the iImar rim o~ the adjacent ring 24, 25 or 26 to form a recoss thereO I~
order to form ~aid annular surface~ 28, an ela~ti~ally de~ormable, easily deformable or remo~able ring may bs : .

' 3 ~ ~

in3erted be~ide each of the metal rings 24, 25 ~d 26 be:eore the casti~ of the concrete used to make the concre-te memb~r formed with thQ a~chox hole 2a. A~
is ~pparent from Figure 3 the in~ertion of the a2lchor 9a, 10a irlto the a~chor hole 2a cause~ the ma~erial of the zones 13~, 14a, 15a to flow radially outwardly a~ far as to the adjacen~ ~nn~ r ~urface 28 ~o that th~
pll~l i ke anchor will be po~itively a;tld frictiorlally held in the anchor hole 2a.

In accordarlce with ~igure 5 the anchor hole 2a compri~es collsecutive retai~i~g zone~ 3bp 4b" 5b and i~ provided with ri~g~ 24b, 25bt 26b corr~pon~;n~ to the rings 24 to 26 o~ Figure 3. Axially ;~ ly o~ each ring 24b9 25bp 26b the in~ide ~urface of the anchor holQ 2b is formed i~ ths a~ociated zo~e 3b, 4b, 5b with ~1 s~nn~ r ~Lrface which i~ radially oul~ d~y off3et ~rom the inner rim of the adjaoe~t ring 24b, 25b, 26b. Adjacent to the ret~1ning zo~e~ the body of the a~chor head 10b i9 ~ormed wi~h ~nn~ grO0ve8 29 30, 31, ~hich have a ~awtooth-ahaped pro~ile i~ axial 3ection and in which pla~tio ri~g~ are embedd~d, ~hi~ch c0~9i8t of a plastic material that ha~ a relati~ely high coe~ficient of ~riction and a relatively high entropy elasticity. ~he plastic rings are ds~i~n~t@d 32, 33, 34.
In that case too the i~ertion of the a~chor hsad 10b into the ~nGhor hole 2b will cause the material of bh~
ri~g~ 32, 33, 34 to flow behind th~ ring~ Z4b, 25b9 26b r~ y outwardly as ~ar a~ to the radially outwardly off~et ~nn~ r ~urface90 2 ~f 3 iJ 3 7 l~

- lL~ -In all am~o~i~ents shown in the ~rawirlgs, the intermediate ~ember orovided hetween the anchor heads 10 and 11 of anchors used to connect the same rinn ~a~/ ~iFfer in l2ngth, Fo~ ~nstance, in or~er to prn~ e we~ae-shaoed gaos between consecutive tubbinq l~inns of the same annular assembly so that the tunn~l lininq ~ay extend along an arc.

The elements 19, 11, an~ 10 and the correspond ing elements 9a, 10a, 10b and 29 are marle of a plastic ma-terial which has entrooy elasticity. Such plastic material in which the molecular structure oF the polymer permits the material to exoand within certain limits after the ma-terial has been compressed. The material i5 molded by the so-called reaction injection molding process so that the isotropic properties of the material are improved. An example of a suitable material consists of the material which is known as "Dowel-~dymer" and i9 available from and has been developed by ~oloplast, Leonding, Austria, in co-operation with the present inventors.

All embodiments shown can be modified within the sco~e of the invention in that the illustrated anchor is replaced by an anchor which has the same exterior shape and is ~ade of a wood which is so arranged that its fibers extend in the lon~itudinal direciton of the anchor so that the forces which are exerted on the anchor as it is fixed in position will act substantially transversely to the direction of the fibers. Said wooden parts may consist each of a plurality of elements, which are joined with glue, and, ~or instance, in the embodiment shown in Figure 1 the wooden body may be provided only outside the part 1a and/or may consist ot annular inserts provided between the rings 2a to Z3.

~ :" ~ ~

.

Claims (13)

1. Means for connecting two adjacent prefabricated concrete members having facing surfaces formed with a plurality of parallel, laterally spaced blind holes, respective ones of the blind holes being axially aligned and each one of the holes having an inside peripheral surface comprising a succession of axially spaced retaining zones increasing in average diameter toward the facing surfaces of the two concrete members, the connecting means comprising a like plurality of plug-like anchors adapted to be forced into the axially aligned blind holes, each one of the anchors being substantially stiff in the axial direction and having respective elongated section adapted to extend axially into a respective blind hole of the axially aligned blind holes, and each one of the elongated sections having a leading end for insertion into the respective blind hole and a periphery comprising a succession of axially extending, substantially cylindrical portions of a plastic material elastically deformable at least in an approximately radial direction for an axially restraining frictional engagement with a respective one of the inside peripheral surface retaining zones of the respective blind hole, the cylindrical portions increasing in diameter in a direction extending away from the leading end, each cylindrical portion comprising a circumferentially extending annular pad of a plastic material which has a higher coefficient of friction than the plastic material of the cylindrical portion and defining an annular groove receiving the annular pad each one of the annular grooves having a succession of sawteeth and the sawteeth of the annular groove having side faces rising toward the leading end.

2. The connecting means of claim 1, wherein the plastic material of the cylindrical portions is metal-reinforced.

3. The connecting means of claim 1, wherein the leading end of each elongated section is tapered, and each blind hole has an end portion tapering inwardly from the facing surfaces toward a first one of the retaining zones.

4. An assembly comprising two adjacent prefabricated concrete members having facing surfaces formed with a plurality of parallel, laterally spaced blind holes, respective ones of the blind holes being axially aligned and each one of the holes having an inside peripheral surface comprising a succession of axially spaced retaining zones increasing in average diameter toward the facing surfaces of the two concrete members, and a like plurality of plug-like anchors adapted to be forced into the axially aligned blind holes, each one of the anchors being substantially stiff in the axial direction and having a respective elongated section adapted to extend axially into a respective blind hole of the axially aligned blind holes, and each one of the elongated sections having a leading end for insertion into the respective blind hole and a periphery comprising a succession of axially extending, substantially cylindrical portions of a plastic material elastically deformable at least in an approximately radial direction for an axially restraining frictional engagement with a respective one of the inside peripheral surface retaining zones of the respective blind hole, the cylindrical portions increasing in diameter in a direction extending away from the leading end, each cylindrical portion comprising a circumferentially extending annular pad of a plastic material which has a higher coefficient of friction than the plastic material of the cylindrical portion and defining an annular groove receiving the annular pad, each one of the annular grooves having a succession of sawteeth and the sawteeth of the annular groove having side faces rising toward the leading end.

5. The assembly of claim 4, wherein the plastic material of the cylindrical portions is metal-reinforced.

6. The assembly of claim 4, wherein the leading end of each elongated section is tapered, and each blind hole has an end portion tapering inwardly from the facing surfaces toward a first one of the retaining zones.

7. Means for connecting two adjacent prefabricated concrete members having facing surfaces formed with a plurality of parallel, laterally spaced blind holes, respective ones of the blind holes being axially aligned and each one of the holes having an inside peripheral surface comprising a succession of axially spaced retaining zones increasing in average diameter toward the facing surfaces of the two concrete members, the connecting means comprising a like plurality of plug-like anchors adapted to be forced into the axially aligned blind holes, each one of the anchors being substantially stiff in the axial direction and having a respective elongated section adapted to extend axially into a respective blind hole of the axially aligned blind holes, and each one of the elongated sections having a leading end for insertion into the respective blind hole and a periphery comprising a succession of axially extending portions of a plastic material elastically deformable at least in an approximately radial direction for an axially restraining frictional engagement with a respective one of the inside peripheral surface retaining zones of the respective blind hole, the portions tapering slightly radially outwardly and increasing in average diameter in a direction extending away from the leading end, each portion comprising a circumferentially extending annular pad of a plastic material which has a higher coefficient of friction than the plastic material of the portion, and each portion defining an annular groove receiving the annular pad, each one of the annular grooves having a succession of sawteeth and the sawteeth of the annular groove having side faces rising toward the leading end.

8. The connecting means of claim 7, wherein the plastic material of the cylindrical portions is metal-reinforced.

9. The connecting means of claim 7, wherein the leading end of each elongated section is tapered, and each blind hole has an end portion tapering inwardly from the facing surfaces toward a first one of the retaining zones.

10. An assembly comprising two adjacent prefabricated concrete members having facing surfaces formed with a plurality of parallel, laterally spaced blind holes, respective ones of the blind holes being axially aligned and each one of the holes having an inside peripheral surface comprising a succession of axially spaced retaining zones increasing in average diameter toward the facing surfaces of the two concrete members, and a like plurality of plug-like anchors adapted to be forced into the axially aligned blind holes, each one of the anchors being substantially stiff in the axial direction and having a respective elongated section adapted to extend axially into a respective blind hole of the axially aligned blind holes, and each one of the elongated sections having a leading end for insertion into the respective blind hole, and each elongated section having a periphery comprising a succession of axially extending portions of a plastic material elastically deformable at least in an approximately radial direction of an axially restraining frictional engagement with a respective one of the inside peripheral surface retaining zones of the respective blind hole, the portions tapering slightly radially outward and increasing in average diameter in a direction extending away from the leading end, each portion comprising a circumferentially extending annular pad of a plastic material which has a higher coefficient of friction than the plastic material of the cylindrical portion, and each portion defining an annular groove receiving the annular pad, each one of the annular grooves having a succession of sawteeth and the sawteeth of the annular groove having side faces rising toward the leading end.

11. Means for connecting two adjacent components having facing surfaces formed with a plurality of parallel, laterally spaced blind holes, each one of said holes having an inside peripheral surface and respective ones of the blind holes in the facing surface of the adjacent components being axially aligned, the connecting means comprising a like plurality of plug-like anchors adapted to be forced into the axially aligned blind holes, each one of said anchors having a respective elongated section adapted to extend axially into a respective blind hole of the axially aligned blind holes and each one of said elongated anchor sections having a leading end for insertion into the respective blind hole, each of said anchors being substantially stiff in the axial direction and each elongated anchor section having a periphery comprising a succession of axially extending portions which are elastically deformable at least in an approximately radial direction for an axially restraining engagement with the inside peripheral surface of a respective one of the axially aligned blind holes, the axially extending portions increasing in average diameter in a direction extending away from the leading end, each anchor having a body of a plastic material reinforced by an axially extending metal tube embedded in the plastic material and axially spaced, radially extending retaining rings embedded in the plastic material, and each one of said axially extending portions comprising an annular pad of a plastic material which is more easily deformable than the plastic anchor body material and has a higher coefficient of friction than the plastic anchor body material, the annular plastic pads surrounding the anchor body and being arranged between successive ones of the retaining rings.

12. An assembly comprising two adjacent components having facing surfaces formed with a plurality of parallel, laterally spaced blind holes, each one of said holes having an inside peripheral surface and respective ones of the blind holes in the facing surfaces of the adjacent components being axially aligned, and a like plurality of plug-like anchors forced into the axially aligned blind holes, each one of the anchors having a respective elongated section extending axially into a respective blind hole of the axially aligned blind holes and each one of said elongated anchor sections having a leading end inserted into the respective blind hole, each of said anchors being substantially stiff in the axial direction and each elongated anchor section having a periphery comprising a succession of axially extending portions which are elastically deformable at least in an approximately radial direction for an axially restraining frictional engagement with the inside peripheral surface of a respective one of the axially aligned blind holes, the axially extending portions increasing in average diameter in a direction extending away from the leading end, the inside peripheral surface of each of said blind holes having a succession of axially spaced retaining zones in axially restraining frictional engagement with a respective one of the elongated anchor section portions, and each of said components comprising a radially inwardly projecting ring in each retaining zone, each of said rings defining an undercut on a side thereof facing away from the facing surfaces of the components and each ring having an inside diameter which is smaller than an outside diameter of an adjacent one of the elongated anchor section portions.

13. The assembly of claim 12, wherein each of the components consists of a prefabricated concrete member and the radially inwardly projecting rings are annular metal inserts embedded in the concrete member.