US2482673A

US2482673A - Drainage system

Info

Publication number: US2482673A
Application number: US3710A
Authority: US
Inventors: Kjellman Walter
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-12-12
Filing date: 1948-01-22
Publication date: 1949-09-20
Anticipated expiration: 1966-09-20

Description

Sept. 20, 1949. w. KJELLMAN DRAINAGE SYSTEM Filed Jan. 22, 1948 Illa v Patented Sept. 20, 1949 v#inwinnen SYSTEM Walter Kaliman, stockholm, smear Application January 22,

194s, .ser-iai No.. 3,1 1c

In Sweden December I2, 1945 Section-1, Public' Law ugust-'llig Patent' expires Decemb'erfIZ; E965- 10 Claims.

This application is a continuation in part replacing. my" copending application Serial No. 636,41,.led December 21, 194:5 now'abandoned", and, as to all common subject matter, relates backl toy said application Serial No.- 636,416,V and to'` foreign applicationsT corresponding thereto for all dates and rights incident tothe lingthereof;

present invention relates-to a drainage system. In. my: oopending application? Serial No; '762,946,1I1havesuggested` to reduce 7,the percentage of'waterin'clay grounds' and similar groundsby the' arrangement oi'vertical band-shaped'fdrains n1l the ground,v said drains-being made from a materiak pervioustolwater. The drains facilitate the' escape of, suchpore Water as is being squeezed out of the ground bythe load that is applied-.- on the ground surface; Thus, the consolidation of the ground is accelerated, the purpose being to increase the carrying capacity of the' ground' and/ or to accelerate settlements. There is a twofold purpose of the band or strip-shape of the drain, firstly to# reduce the amount of drain material in relation to the area of ciontactbetweenV drain and soil, l the draining effect being dependent mainly on. the: size of said area, and, secondly, to render the drain flexible so that it can be'rolled on a drumv and easily transported and handled.

The material ofr said drains must be very porous, and the pores must be large, .inorder that the permeability of the drain-.to water shallbe sufficient in theflongitudinal directionthereof.. Furthermorathemateral mustI be capableof withstandingthe horizontal earth pressure without loosing too much ilo-permeability. Finally,`even very small. soil4 grains .must be prevented fromenteringthepores of the material, because they cou-ld clog there, thus reducing the permeability of the drain. In certain cases it has been found diicult to answer all oi these requirements- It is the object of the presen-t inventionto. pro- Vide band-shaped draining means. which are capable of withstanding the earth pressureand into which soilgrai'ns cannot penetrate, while the drainingV meansyet have suicient permeability.

In the drawings: Y y l Y Fig. 1 is a horizontal sectional View substantially at' right' angles' to the longitudinal direction of a drain and' showing one form of the invention Fig. 2 isa horizontal sectional 'View of a modi'- ed form of the invention; y

Fig. 3 is a verticaly section oi part of a drainage' system comprising drains of the type illustrated in Fig. l or Fig'. 2, the drains being shown in sections along thek line III-III'in Fig. 1 or Fig; 2';

Fig. 4 is a horizontal section of part of another embodiment ofthe invention;

Fig. 51 is a vertical section taken on the line. V-V of Fig'. 4'; and 1' Fig. 6 is a similar vertical sectionalview of a.: slightly modified embodiment of the; invention.v

While the drain according tof the inventionmay have' any suitable' croSsLsectiong. I. have illus.'- trateds-by of example,l some drains ai nrrovrY substantially rectangular cross-section eac Y v The drainaccording to Fig. lfismadeby1 tastening twostrip'or band-shaped layers-l and 2. oli a: uniform width. together, the' surface ot the one layerl iacingthe other layer 2.-' being i channelled inthe longitudinal' direction oi.- the drain.- VThe channels Aform internal passages; 3ffinthe` drain, the twoflayers. bearing; oneacim other at the: proiectionsd.' Y 1 According to the.- embodiment shown in-Fig.. 2; the drain cons-istsoi three layers',L the outer: lay.- ersfb and l-y beingof` a, material Apervionsi to'v water. and capab1le of. preventing vfine soilgrainstrOm passing: therethrough,. iwhereasthew intermediate layer averygreat fperrneability4 in theflongitudinal, directionoaf.. the drain and is'able to withstand the horizontal@ earth. pressure,A transmitted by the outer layers, Without-loosirz; too nmcth ot its permeability; In the example; illustratedY in Fig.. 2, stripsor bars 5 are suitably spacedeinparal-lel-between two non-channelled; layers 6 and. 1f, and the whole. structure Vis fastened together-so; astufo-:n1x longitudinal passages. 3. K t The fastening may be eiected by gluing along the two edges of the drain ,and-,.ifstrips-or barsi are used, at individualfpointsf in :the interior oi, the drain. Y Instead of gluing., clampingiory sewing may be used..

Laboratory innestigationsi have shown that the drains may beY made. of ordinary,unsized4 cardboard.- or similar flexible materials. They are made, vr-for instance, of. ath-icknessoi one eighth oi an inch` and on a widthof-four. inches with pas-- sages `ofthe crossfsection 1*/25 :e1/z5 inches atl-mutual-.distances of one fifth` of aninch,V and, the length. oi.' each. drain may amounttoffor instance, 5 to 60 feet. 5

, -In Fig.. 3 I haveshown a section ot adrainage system.Y With-substantially vertical.: drains A, B,y and C in their positionsin` aground 8 the sur.- fae of. which. is indicated at.Y `For the. sake of clearness, the thickness-of` the.v drainsgis exaggerated` in.l this ligure. According-.to the peizmeability andreompressibility of the andthe widthand permeability of.` thedrain, andthe rate at which the consolidation. of the soil isA wanted to take, place, the spacingd; of the drainsfA-B,. C is calculated theoretically.. It may vary, for instance, between 3 and 10 feet butshould.- be the same, or: nearly the same, inthe planeet Fig 3`v as the: direction perpendicular thereto.. Aswill. be seen from. Fig. 3,A the upper ends of the drains are shghtly projecting above the suriace l1 oi they ground, while the lower ends ofthe drains are terinitiating in thevground. rfla-layer t0 consisting o Sandor gravelgifs placeduponithge.k surface 3;, the

3 height of said layer being somewhat greater than the height of the projecting portions of the drains. Resting on the layer I0, there is a diagrammatically indicated embankment II, such as for a highway or a runway for airplanes, exerting a vertical load on the ground 8.

Any suitable means may be used for driving the drains into the ground, an appropriate device for that purpose being described in my above named application Serial No. 762,946.

The material of which the drains consist should be pervious to water, but the pores must be relatively s-mall so as to prevent earth from intruding the drains and obstructing the ilow of water.`

In cases where the earth pressure on the drain is very great, it is necessary, for the purpose of preventing a collapse of the passages, to increase the strength of the drain material in a wet state, Which is effected by suitable impregnation. It should then be attended to, however, that the permeability of the drain material is not impaired too much. Further, the drain should be compressible in the longitudinal direction so as to be able to take part in the vertical compression ofthe ground without being damaged.

- From any point of thesurrounding earth, the water squeezed out by the load flows approximately perpendicularly to the nearest drain, as indicated by the arrows in Fig. 3, and enters the passages 3. Since there is no outlet at the lower end of the drain, the water travels upwards in the passages 3 and, at the upper end of the drain, enters the sand r gravel layer lil. In this layer, the water liows laterally until being caught by a suitable surface drainage system, if any, not shown in the drawing, or else it` flows out from under the embankment.

Laboratory tests have proved that the permeability in the longitudinal direction of a drain according to Fig. 2 is surprisingly gre-at as cornpared with that of a drain without passages. Thus, thanks to the provision of the passages, the spacing: of the drains can be increased, which, of course means economy.

Another embodiment is shown in Figs. 4 and 5 wherein the drain consists of a single 'stripV or band I2 of a flexible material pervious to water and a passage or tube I3 arranged outside the edge of the strip. The passage is formed by a wire helix I4 which is retained in position by means of a. securing strap I5 attached to the band, said strap also preventing the `earth from penetrating into the helix and in between the helix and the band. The passage I 3 is open at its top and terminates near the surface of' the ground.

If the band material is of inferior strength in a wet state, it is possible to prevent the same from penetrating into the helix by the edge of the band facing the helix being lined with a filtering strip I6 from fabric or some other suitable material pervious to water, the filtering strip being retained in position by the securing strap I5. The water entering the band I2 from the surrounding earth will ow into the passage I3 substantially in the direction of the arrows shown in Fig. 5 and will then continue to flow upwardly through the passage.

If desired, the wire helix may be made fromV other material than metal, and it may also beY replaced by a perforated tube, consisting, for instance, of network, as shown at I 4a in Fig. 6. The securing strap I5 may consist of fabric, cloth, water-proof paper or the like, and it may be secured to the band such as by sewing, past- .4 ing or stitching. The band may consist of any suitable number of layers. If required, the drain may be provided with a passage at the other edge as well. One or more .passages in the interior of the drain are also conceivable, each of Isuch passages being provided with a wire helix or the like, the same being :covered by a lter, if de- 'sired.

As will be seen from Figs. 1 and 2, the passages 3 are arranged relative to the appertaining strip or band so that parts of said strip, as viewed at right angles to their surfaces, are free from passages. As these parts are more rigid against the earth pressure than the parts traversed by passages, the earth pressure will distribute itself unevenly and be greater at the first-named parts than at the latter parts. Thus, to a certain extent the soil itself will bridge over the parts traversed by passages.

The longitudinal passage or passages in the drains may obviously be provided by means other than those shown and described by way of example. The invention is obviously not limited to a plurality of passages in the drains.

While in the foregoing description I have confined my consideration to vertical drains, it will be understood that the invention is not confined to exactly vertical drains andpassage means, but may equally well beV embodied by the use of drains having passage means located at an acute angle with respect to the surface of the ground, for instance, between and 45.

What I claim is:

1. In a drainage system for accelerating the consolidation of grounds having a very low permeability to water, a plurality of laterally interspaced drains placed in the ground, each of said drains comprising a exible strip exerted to lateral earth pressure and consisting of a material pervious to water, and said strip having passages extending longitudinally of the drain and opened at the outer end thereof to permit water squeezed out of the surrounding earth through said strip to flow through said passages.

2. In a drainage system forl accelerating the consolidation of loaded grounds having a very low permeability to Water, a plurality of laterally interspaced drains placed in theground, each of said drains comprising a flexible strip exerted to lateral earth pressure and consisting of a material pervious to water, and substantially'vertically extending passages in said strip, said passages being open at their tops and terminating near the surface of the ground, whereby to permit water squeezed out of the surrounding earth through said strip to flow upwards through said passages onto said surface, said passages being arranged in said strip so that parts of said strip, as viewed at right angles to the surface of the strip, are free from passages.

3. In a drainage system for accelerating the consolidation of loaded grounds having a very low permeability to water, a plurality of laterally interspaced drains placed in the ground, each of said drains comprising a flexible strip exerted to lateral earth pressure and consisting of a material pervious to water, said strip comprising band-shaped layers fastened to each other, the surfaces of said layers facing each other having different geometric shapes so as to provide substantially Vertical internal passages therebetween, said passages being open at their tops and terminating near the surface of the ground, whereby to permit watersq'ueezed 'out f the sur i rounding earth through said strip to ow upwards through lsaid passages onto said surface.

4. In a drainage system for accelerating the consolidation of loaded grounds having Ya very low permeability to water, a plurality of laterally interspaced drains placed in the ground, each of said drains comprising a flexible strip exerted to lateral earth pressure and consisting of a material pervious to water, said strip consisting of three layers, the outer layers being of a material pervious to water and capable of preventing fine soil grains from passing therethrough, and the intermediate layer having a great permeability in its longitudinal direction and being adapted to withstand the horizontal earth pressure, transmitted by said outer layers, without loosing too much of its permeability.

5. In a drainage system for accelerating the consolidation of loaded grounds having a very low permeability to water, a plurality of laterally interspaced drains placed in the ground, each of said drains comprising a ilexible strip exerted to lateral earth pressure and consisting of a material pervious to water, said strip comprising three interconnected band-shaped layers, the intermediate one of said layers consisting of interspaced bars so as to form substantially vertical internal passages, said passages being open at their tops and terminating near the surface of the ground, whereby to permit Water squeezed out of the surrounding earth through said strip to flow upwards through said passages onto said surface.

6. In a drainage system for accelerating the consolidation of loaded grounds having a very low permeability to water, a plurality of laterally interspaced drains placed in the ground, each of said drains comprising a flexible strip exerted to lateral earth pressure and consisting of a material pervious to water, and a flexible perforated tube extending substantially vertically and secured to an edge of said strip, said tube being open at the top and terminating near the surface of the ground, whereby to permit water squeezed out of the surrounding earth through said strip and entering said tube to flow upwards therethrough onto said surface.

7. In a drainage system for accelerating the consolidation of loaded grounds having a very low permeability to water, a plurality of laterally interspaced drains placed in the ground, each of said drains comprising a flexible strip exerted to lateral earth pressure and consisting of a material pervious to water, and a wire helix forming a flexible perforated tube extending substantially vertically and secured to an edge of said strip, said tube being open at the top and terminating near the surface of the ground, whereby to permit water squeezed out of the surrounding earth through said Strp and entering said tube to flow upwards'therethrough onto said surface. Y

8. In a drainage system for accelerating the consolidation of loaded grounds having a very low permeability to water, a plurality of laterally interspaced drains placed in the ground, each of said drains comprising a flexible strip exerted to lateral earth pressure and consisting of a material pervious to water, and a flexible network forming a perforated tube extending substantially vertically and secured to an edge of said strip, said tube being open at the top and terminating near the surface of the ground, whereby to permit Water squeezed out of the surrounding earth through said strip and entering vsaid tube to flow upwards therethrough onto said surface.

9. In a drainage system for accelerating the consolidation of loaded grounds having a very low permeability to water, a plurality of laterally interspaced drains placedy in the ground, each of said drains comprising a flexible strip exerted to lateral earth pressure and consisting of a material pervious to water, a flexible perforated tube extending substantially vertically and secured to an edge of said strip, said tube being open at the top and terminating near the surface of the ground, whereby to permit water squeezed out of the surrounding earth through said strip and entering said tube to flow upwards therethrough onto said surface, and a layer of a material pervious to water between said strip and said tube.

l0. In a drainage system for accelerating the consolidation of loaded grounds having a very low permeability to water, a plurality of laterally interspaced drains placed inthe ground, each of said drains comprising a flexible strip exerted to lateral earth pressure and consisting of a material pervious to Water, a flexible perforated tube extending substantially vertically and secured to an edge of said strip, said tube being open at the top and terminating near the surface of the ground, whereby to permit water squeezed out of the surrounding earth through said strip and entering said tube to flowY upwards therethrough onto said surface, and a longitudinal strap pervious to water, said vstrap surroundingsaid tube and being secured to said strip.

WALTER KJ ELLMAN.

No references cited.