US2568010A - Process for the production of a lining for pressure galleries and shafts - Google Patents

Description

Sept. 18, 1951 A. KlEsER 2,568,010

PROCESS FOR THE PRODUCTION OF A LINING FOR PRESSURE GALLERIES AND SHAFTS Filed May 7, 1947 2 Sheets-Sheet 1 if Aff f"` f J' 'S /m/exar A10/s A7595? Sept. 18, 1951 A. KlEsER 2,568,010

l PROCESS FOR THE PRODUCTION 0F A LINING FOR PRESSURE GALLERIES AND SHAFTS Filed May 7, 1947 2 Sheets-Sheet 2 Patented Sept. 18, 1951 OFFICE PROCESS FOR THE PRODUCTION OF A LINING FOR PRESSURE GALLERIES AND SHAFTS Alois Kieser, Bregenz, Austria Application May 7, 1947, Serial No. 746,476 In Germany July 27, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires July 27, 1963 8 Claims.

Various processes have been proposed already to prevent the formation of cracks in the lining of pressure tunnels, pressureshafts and other structures subjected to high operating pressure, in which processes the lining is to be placed under such an initial pressure,` by means of pressed concrete, that the compressive stress caused thereby in the lining exceeds the tensile stress caused by the operating pressure. With these known processes, however, the required initial pressure cannot be achieved, partly because they suffer from structural faults and partly because they do not fullill the theoretical conditions. All known processes have this common feature that the pressed concrete is introduced directly into the hollow space between the rock surface and an expandable shell or an inner core ring formed of concrete or shaped blocks. Such a cross sectional structure, however, suiers from the drawback that it hinders the appropriate installing of the shell or the inner core ring, above all in "ravelly rock. Moreover, the hollow space to be lled with backing-up material greatly varies in thickness owing to the irregular tunnel bore so that, apart from a high consumption in eX- pansive pressed mortar, the initial pressure is impaired by the shrinkage of the comparatively thick and irregular mortar ring. Moreover, the known processes do not provide for actually holding the pressure required for the initial pressure at the correct level until the pressed mortar has hardened.

The `drawbacks that are only briefly indicated above, are avoided according to the invention in that an outer lining ring adjacent to vthe surrounding rock and an inner core ring are provided, leaving an v4annular space between both rings, and that the core ring is placed under an initial pressure by pressing a filling and sealing mass into the hollow space formed between the core and lining rings in order to effectively prevent the formation of cracks in the core ring and thus to prevent water losses, when the tunnel tubes are subjected to pressure.

For this purpose it is possible either to provide for a spacing insertion of corrugated iron between the core and lining rings or to wall up the core ring of shaped blocks of concrete or another suitable building material so that the hollow space between the core and lining rings is provided, e. g. by the special structure of the outside surface of the shaped blocks.

Annular partitioning and sealing elements, perpendicular to the tunnel axis, are provided in vsaid annular space, for subdividing saidspace into separate zones, which are successively lilled with a material which is allowed to harden under pressure.

In the drawing the object of the invention is exemplified with reference to two modes of execution, Fig. l illustrating a pressure gallery in crosssection according to the rst mode at the left without and at the right with a Torkret collar, whilst Fig. 2 is a longitudinal section of same, and Fig. 3 the medium top or crest part of Fig. 2, on an enlarged scale. Fig. 4 is a section taken in the line A-*A of Fig. 3, Fig. 5 illustrates a crest cross-section through the second mode of execution of the pressure gallery wherein the section on the left half of the figure is taken on the line F-F of Fig. 6 within the range of the "Torkret" collar, and on the right half of the figure outside of said range. In contradistin'ction thereto the left part of Fig. 6 relates to a section along the line B-B displaced into the crest plane, whilst the right hand part of this figure is a section taken along the line C-C of Fig. 5. Finally Fig. '7 is a moulded or proilated brick as required, seen from above, Whereas the Fig. 8 is a section taken on the line D-D, and Fig. 9 a section taken along the line El-E of Fig. '7. Fig. 10 is a perspective view of a molded zone edge block used in the core ring.

With both modes of execution a lining b is produced adjacent to the rock a. The concrete utilized for same need not be of a high grade. In solid rocks a minimum thickness of 10-15 cm. will suffice, whilst if the rock is not rigid the lining ring will have to resist the pressure of the soil, and must accordingly be of adequate thickness. The lining ring b can be made of concrete in the usual manner. It is economically advantageous to employ a portable scaliolding iitted with iron shuttering (boarding), the concrete being introduced according to the pumping process. The latter is also advisable as it permits to reduce the thickness of the lining, and consequently the volume of rock to be broken out.

According to the rst mode of execution as illustrated in the Figures 1-4 the lining ring b encloses an annular hollow c with corrugated iron insets, as customary in trade, made from black sheet, or for barring out iron as constructing material, with corrugated plates made of Eternit (artificial slate), or any other suitable substitute. A special design of the corrugated inset e. g. in sernicircular shape tted with ribs perpendicularly located in respect to the gallery axis would considerably simplify the insertion. The individual parts of the corrugated insets are laid without joint tightening in such a manner as to overlap on all sides, and are fastened to the curved wall surfaces, so that they are prevented from .detach-ing or separating. With the ribs located transversely the stiiness will facilitate the insertion and the fixation; on the other hand in this case an inset must be used rounded according to the inner diameter o f the lining ring b. Y

On the walls, and at the tunnel crest more points of fixation are required than on the floor or bottom. The longitudinal and transversal joints need not be tightened asit is desirous that a portion of the packing mass should penetrate between the corrugated inset and the core ring the packing masses in this direction may be secured by appropriate recesses in the moulded or proiilated bricks. In each zone special blocks are provided to contain the i'illingand the pressure gauging tubes (pipes) f. The use of moulded bricks not only renders superuous the distance insets, but at the same time facilitates the construction ofthe core ring closely adjoining the for filling hollows, if any, and for increasing the density of said ring. If necessary, this process may be furthered by boring additional holes into the corrugated inset.

vAccording to the iirst-mode of execution a core ring e madeof concrete is arranged within the corrugated inset d, the concrete having to be of adequate strength and density. For introducing the concrete any of the methods hitherto used maybe employed. The fact-that the outer curved wail ofthe tunnel is not formed by the rocks, but byY the lining ring filled with the corrugated inset facilitates the irreproachable production of ahigh gradeconcrete for the core ring calculated in `conformity' with the principles of statics. Special'economic advantages are realized by introducing the concrete in one casting operation according tothe pumping process.

At' certain intervalsr tightening rings h are provided contiguous tothe lining ring b and corresponding to the height of the corrugated insert. These rings are produced by groove-shaped recesses in the ,shuttering (boarding) provided inthe course o f making the concrete lining ring. These tightening rings close the hollows c so as to `create zones separatedfrom each other.

1n the concrete of the core ringe the lling and pressure gauging tubes (pipes) f are embedded ,connecting the interior of. the core ring Witheach zone ofthe hollow c.

Opposite to the filling tubes (pipes) f1 filling grooves g are provided in each zone in the lining ring b. Besides recesses are left open inv suitable .distances in the lining ring b` so as to warrant themobility of thepacking masses perpendicularly `to the ribs of the corrugated inset because of the ribs considerably narrowing the cross-section ,of flow in this direction.

Withbothmodes of execution bore-holes i are provided leading. through the lining ring l2` into thev rock a. Besides a draining pipe 7c islaid inthe lower part of the ring which may be closed .by agate valve Z.

According yto the second mode .of execution the .corering-is composed of moulded or profllated `bricks m made `of concrete or any other suitable building material, and located close to the lining ring b. With the exception of the .crown no cor- A`rugafted. insets are employed whereas in their :stead the -outer i aces of the moulded or prolated bricks are furnished withundulatory ribs n. The

mortarjoints inthe zplanes perpendicular to the ringgaxis are formed into wedge joints o for self- .tignteningnnder inner pressure. The axial joints o .are also .filled with mortar. The tightening inHres'pect 4to .the neighbouring zones is effected .hy-the insertion of zone-margin bricks p, the projectionsp of lwhich will contact thelining ring b along the zone margin without leaving any gaps, so that with this mode of design the' tightlining ring. A scaffolding is only required for the vaults wl-iichv consequently are not started `building before the lower half of the core ring is completed. For warranting the right distance beingkept in regard to the lining ring b the crown g of the core ring is furnished with a corrugated iron inset .d'with concrete or pressed mortar.

The initiai pressure in the core ring is brought about Vby pressing the necessary quantity of material into .the hollows c and the chambers, bores', grooves, cracks, etc. adjoining which process may rightly be called the packing of the core ring'. For this purpose the packing or filling is carried out byy -zones by `way of simultaneouslyV utilizing all filling tubes (pipes) f of one zone wh-ile checking the initial or preliminary pressure actually atta-ined in Vthe --packing ring. I-t is advisable to employ packing masses having hydraulic qualities such asare capable of setting and hardening. In this case the pressure conditions existing at the time of setting are maintained unalterated after hardening provided that no change of temperature occurs. An appropriate lling havin grhydraulicproperties is e. g'. a cement-sandwater mixture of the actually most favourable mixing ratio. This yfill-ing mass-renders necessary a subdivision of the packing process into five individualV phases, viz.

1 shawl- For thoroughly mostenine thehollows water is, al? s hort intervals, pumped into .under moderate pressure and then drained .01T again v2.v phase-:.-Coarse-iilling mortar is introduced up to saturation equally under a moderate pressure.

3 phase-Without reducing the pressure the filling device isswitched over to fine mortar, and later on to cement milk, whereby the pressure is gradually increased up to the maximum pressure desired.

4 masa-Before the packing mass starts setting the filling device is switched over to water, also without reducing the pressure and continues .to operate-in lthis manner Iuntil the; packing mass hascompletely set and has sumciently hardened, so as to warrant the initial compressive stress ofthe .core ring as required.

5 phase- High pressure filling and packing by means ofy cement milk or any other appropriate tightening means. This phase follows phase 4 at a certain interval, and is intended to ll hollows left empty by the pressing water in connection to the filling tubes (pipes) in the packing chamber.

If the initiall pressure need not be mentioned at its fullvalue it is also possible to employ masses having no hydraulic properties such as bitumen, loam. andthe like. In this case a sufficient prelimina-ry tension is only maintained if the filler is prevented from'gradually escaping under the' initial pressure, and in particular if the filling and pressure gauging tubes (pipes) are carefully closed. l

The packing process described Warrants a sufcient static security againsta high inner pressure or against an outer pressure, if any, even-l tually occurring with the gallery tube discharged.

The core ring is in this case imparted anV initial pressure preventing the formation of Atensile strains and, consequently, cracks under the action of the service pressure. In the course of the packing operation it is desirable that cracks and fissures should be formed in the concrete mass of the outer ring as shown in Figs. -8 so as to open the way for the packing as far as possible into the clefts and crevicesV of the surrounding rocks. For accelerating the` flow of the mortar into the hollows outside of the lining ring b the holes i are used which are bored into the rocks through the concrete layer.

The packing process described transforms the entire envelope of the core ring into a tightly compressed mass in which the fragments of the outer lining ring after its rupture are solidly cemented to the core ring by means of the packmg For example a tunnel may have an interior diameter of the inner ring i. e. of the tunnel tube proper of 2.40 in. an outer diameter of 2.80 corresponding to a ring thickness of cm. and an initial pressure of 100 m. water column, yielding annular compressive strains of 7.0 kg./cm.2 so that at the cube strength of 280 kg./cm.2 a factor of safety results amounting to 4 (on basis of an approximate calculation using the simple ring formula, and neglecting both the proper weight of the ring and the pressure difference between the iioor and the crown). Without setting up tensile strains in the core this gallery may be loaded interiorly with a water pressure of In all cases in which the initial pressure desired cannot be attained during the packing phase 3 owing to the numerous clefts of the rocks, or cannot be maintained at the level desired so that great losses of water escaping into the rocks cannot be avoided during phase 4, a reinforced Torkret collar r must be inserted, whereby the dimensions of the reinforcing organs s are determined unequivocally by the difference of pressure between the initial pressure actually attained in the course of phase 3, and ascertained by means of pressure verii'lcators and the initial pressure desired. The lacking initial pressure per unity of length equal to the pressure difference multiplied by the outer core ring diameter is to be eked out by the iron tensile force of the collar per unity of length. As iron willon principleonly be inserted in those zones in which the lining cannot be given the necessary safety in any other manner, and as the dimensions of the reinforcements s will depend on the actual requirements, a great economy in the use of iron is warranted by the method described.

If a tunnel executed in conformity with the second mode of construction according to the Figs. 5-9 requires smooth walls for hydraulical rreasons an appropriate plaster t will be applied to the inner Walls of the tunnel.

Apart from the pressure tunnels passing through rocks the process described may be used for all diameters occurring in hydraulic plantsf pressure shafts.-

elements perpendicularV to the tunnel axis in said annular space, for subdividing said space into separate zones, and elements for spacing the core'ring from the lining ring at a plurality of points in each zone.

2. A lining for pressure tunnels, comprising an inner core ring, an annular space enclosing said core ring and filled with a backing up material under'initial pressure for exercising on said core= ring an initial compressive stress, an outer lining ring between said annular space and the surrounding rock, annular partitioning and sealing elements perpendicular to the tunnel axis is said annular space, for subdividing said space into separate zones, elements for spacing the core ring from the lining ring at a plurality of points in eachzone, and tubes inserted through said core ring and communicatingwith each zone of said annular space.

3. A lining for pressure tunnels, comprising an inner core ring, an annular/space enclosing said core ring and filled with a backing up material under initial pressure for exercising on said core ring an initial compressive stress, an outer lining ring between said annular space and the surrounding rock, annular partitioning and sealing elements perpendicular to the tunnel axis in said annular space, for subdividing said space into separate zones, elements for spacing the core ring from' the lining ring at a plurality of points in each zone, and grooves on the inside surface of said lining ring in each zone of said annular space.

4. A lining for pressure-tunnels, comprising an inner core ring, an annular space enclosing said core ring and filled with a backing up material ,under initial pressure for exercising on said core ring an initial compressive stress, an outer lining ring between said annular space and the surrounding rock, annular partitioning and sealing elements perpendicular to the tunnel axis in said annular space, for subdividing said space into separate zones, and corrugated iron sheets for spacing the core ring from the lining ring at a plurality of points in each zone.

5. A lining for pressure tunnels, comprising an inner core ring which comprises molded blocks having protrusions on their outside surface, an annular space enclosing said core ring and filled with a backing up material under initial pressure for exercising on said core ring an initial compressiVe stress, an outer lining ring between said annular space and the surrounding rock, said protrusions of the molded blocks of the core ring spacing thelining ring from the core ring, and annular partitioning and sealing elements perpendicular to the tunnel axis in said annular space, for subdividing said space into separate zones.

6. A lining for pressure tunnels, comprising an inner core ring which comprises molded blocks having protrusions on their outside surface, an annular space enclosing said core ring and filled with a backing up material under initial pressure for exercising on said core ring an initial com- 72 preserve stresse-an onteriliningfringzbetweerrsaid annularfzspacm andfthei-L surroundingrock; said: protrusions of the molded blocks offsthef, verering spacingrthe:dining'` ring f-romffthe.1 commingv atr a plurality of; points;` in-:eaohizoneiwan'annular partitioning 'f and 'sealing2 elements,- perpendiculartogthe'ftunnel axis ein;:saidannular spaeeafor. subd-'ngidingsaid Vspaceinto,4 separate; zones; said an-- nular' i--partitioning.fJandv sealingf elementsV being` cSJmDOsedof zone.;edge; blocks' of the.' corey ringfhainggspeciai; fpretrusions.

'1; l; Asprocess foneonstructing a 1ining;for;pressure tunnels; compiingithe steps `of-,zcoveringitheV malta-surface. offthegtunnel'with arlininaaringg constructing an inner core ring; so; as@ tu leave between; v'sa-id; rings? an: annular@ spaeeyr-:pririding inisaidsannularf:spaeefrelements perpendicular: tot tlieiftunnelriairis: forssubdividing; saidispace: into*- zen'es which-areitightly:separatedfromseach other, filling; eaehzone with: as liquidb'ackingupz mater-1y rial;A and' pressurizing.l said: backingy up =f material whilef'allwingir it to= Hardenl :soi that Jthelrardened Eackingr up materiali exercises cm1 saidffcore: ring an;initialgvcompressive stress;

8'. 1A mproeessafbrf constructing "a'liningfrfv preseL sureitunnels; comprising the stepsoflooveringfthe rocio surfacef ofi: theftunnelwith a: fliningrring; cnnstructingranfinnen coreiring rso as to leave be"- tween-said rings. an annular Spacey; providing;-7 injy saidvannular-fspaeeelements perpendicular'tthev tunnel axis forsubdividing` said spacedntolzones:

which are tightly separated from each other.. y lli-ngeachtzone with a. liquid backing-upmaterial untiluaJ .predetermined .pressure hasbeemreached.

interrupting-the .owof the-*backingv up-material,A

and hydraulically pressurizing.saidibacking up':

material, while, .allowing it to i hardeny so. that the'l hardening, backing.. up material exercises ,onsaidl core, ring, an initial compressive stress.-

Theriollowingi references -are of; record: mathe'.

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