US1671679A - Method of increasing the supporting strength of conduits - Google Patents

Description

May 29, 1928. 1,671,679

A. MARSTON V METHOD OF INCREASING THE SUPPORTING STRENGTH OF' CONDUITS Filed Sept. 12, 1924 l Patented May 29, 1928s. l

UNITED( STATES o i 1,671,679 PATENT OFFICE.-

ANBON MARBTON, 0F AMES, IOWA, ASSIGNOB T0 IOWA STATECOLLEGE OFGBICUL- TUBE AND MECHANIC ARTS, 0F AMES, IGWAyAL CORPORATION 0F IOWA.. i

mE'rHon on' INCBEASINGKTHE SUPPORTING STRENGTH or `ooimurrfs.

Application `tiled September 12, 1924. 4 Serial No. 787,371.`

VVlnenr large conduits `of concreteorfother material are` laid in trenches,` und` the trenches are subsequently filled with earth or other material,` and also when 4suoli `are laid on an solid surface prOJeGtmgu'pwardly into" lied areas, it` frequently 0ccurs that the conduits 'will be cracked or crushed afterltheearthsettles.; This is owing to insufficient supportingstrength of the conduit, which at times, is often `partly, due

to the tact that it frequently happenslthat a duit is y iirmly and `uniformly supported throughout its length, softhatf crushing strains a pliedto the u per surfaces will be resisted y the entire ody ofthe conduit,

`and will not be unevenly distributedlupon `certain points or parts thereof", L g

A further object is to provide an imf proved' method of reinforcing the top "portion es well as the sidesl and bottolnjportions l of conduite S05 asto give greater inherent supporting 4'strength to resist crushing strains` d 'fo l `My invention consists 1n the method of metal and concrete atthe `bottom and sides of a conduit, whereby the conduit- His uniformly and evenly supported "at its bottom, andalso in the improved `method of applyingreili- `forcing metal and concrete around `the conduit,

whereby objects 'contemlatedy are attalned, as hereinafter more ully set forth, pointed out in my claims, Iand' illustrated inthe accompanying drawings, 1n` which:

, force by my improved method, with c portion ofthe trench adjacent thereto `prepared in accordance with my improved Imeth'od to receive a" conduit and reinforcing metal and concrete. A y i Figure 2 shows a transverse sectional View kthrough a `trench and a conduit provided lwith, reinforcements applied in accordance with myimproved method. c o v y o Figure 3 shows a transverse sectional view of a trench having portions of its bottom and sides cut` away as required in carrying out my imprOVedmethod; and f Figure 4 shows atransverse sectional view throuh a trench and culvert showing a,de` vice o y t "and, meta-ly at the upper portions of the conor` retaining the reinforcing;` concrete duits, andfllustrating one means' by which my improved method may be carried out. y Betel-rino. to the `accompanying drawings,

I'have `illus rated an ordinary trench formed in the earth to `receive "a conduit. The boty tomof the trench is indicated generally by the numeral 10 and the sides are indicated generally by the numeral 1l. My method `is,

also used for conduits notlad in trenches,l but '-the conduit which is of the ordinary kind 110W` lncolnnion `use is indicated by the numeral 12. r y l Before laying each section of conduit, the

` operator employs a rounded spade or `other implement land `scoops out from the hottom ofthe trench,` or from any other solid` sm'- Vface on `which the conduit is' to laid, two or y more rounded curved depressions 13.' `When the conduit islaldfm a trench so narrowas to require it, he also, directly above each ond of thedepression 13", scoops out a rounded semi-cireularjrec'ess 14 from the earth at the "sides of the trench. He then places metal y i y' reinforcing wires, rods or barsl in the dekpreparing; the trench to receive relnforclngfprgggong `,133, and" yalso; other reinforcing vWires, rods or harsl and 17 respectively at `the sides and top of the conduit. The reinforcing Wires, rods or bars 115,116 and 17in-ay y be combined. The double lines of reinforc` rings" leerecastbefore the culvert put into position,I but when the reinforcing applied after the conduit is laid, the outside reinforcing bars 15, 16, 17 and`18 may be omitted. o y

The operator then places a quantity of concrete material in thel depressions, 13, and then `heolaces the conduit in position resting upon said concrete material, and also upon the hottolnof the trench, or other solid sul face on rwhich the conduit is laid. between the depressions 13. After this vhasbeen done, heplacesconcretematerial around the sides and top of the conduit and around the reinforcim'er hars `16 and/17 toform projecting rings 18 of reinforcedconcrete around the `body of the conduit, assliown inFigure 1. o

When lacing this concrete lmaterial to form reinibrcin rings 18, it is sometimes desirable to empiiiy a series of concrete retainingy forms 19 in the trench-on `opposite sides of the particular ring 18 which is then being formed of concrete material, and this is necessary when the conduit is not laid in a trench. These retaining forms 19 may be shaped as illustrated in the drawings, with their side edges of a width to loosely tit the interioi of the trench, and their lower ends shaped to project downwardly between the conduitand the adjacent sides of the trench, to thereby prevent the concrete material from moving in directions longitudinally of the conduit. The retainin forms must have an outer member when tie conduit is not laid in a trench. When the concrete material has set, these retaining forms may be removed and repeatedly used. The various reinforcing wires, rods or bars 15, 16 and 17 are arranged with theirends inoverlapping position within the concrete material, thus forming the reinforced continuous rings 18 completely encircling the conduit.

In practice with my improved method of increasin@ the su ortino stren li of conduits, I have found that thesupporting` strength of the conduits may be increased to a very considerable extent at a comparatively slight cost, because the work of preparing the depressions and' recesses atthe bottoml and sides of the trench can be very quickly and easily done by ordinary workmen, and these recessesand depressions perform the double function of providing a means Whereby the reinforcing concrete material may be easily positioned under and at the sidesofAV the conduit, and they also form a sort of mold or receptaclein which this concrete material andreinforcen'ient can be retained while setting and hardening. However, 1n

some cases I find it desirable to construct my` reinforcing rings 18 around the conduit before laying it in position.

.The results, as to increasing the support ing strength of the conduits when my improved method is practiced, are much greater than though the'corresponding amount of reinforcing concrete and metal were appliedL to the conduitsotherwise, because no matter how much reinforcement is applied to the conduits, their resistance to crushing strains depends to a material extent upon whether or not their bottom and sidey portions` rest firmly and uniformly upon a solid founda- 18 around the conduit before placin tion, which cannot be obtained by simply laying the reinforced conduits on the bottom of an ordinary trench. In cases where I find it desirable to construct my reinforcing rings it in position, I make the depressions 13 s ightly larger than the exterior of the rings 18 and insert soft concrete between the rings and the earth.

Vare `sup orted inl such a `wa Furthermore, the strength added to a conduit by lnetal reinforcing depends to a large degree upon the distance between the outer and inner reinforcing bars, which in my^improved method may be veryf large in the reinforcing rings 18 as com aired with the small distance availablein t ecomparatively thin shell or wall of the conduit.

Furthermore, accordin to my improved method, the conduits'are rmly held against longitudinal movement in the trench. y

When the 'bottom and sides of a conduit that the sides cannot distorted outwal pressure I0 `in yresisting crushin ,strainsl from above is materially. increase and according'y to my method, the concrete reinforcements that engage the sides of the` culvert are held together by the reinforcements imbedded in concrete thatextend across the top of the culvert. Hence, pressures applied on topy of the culvert will be. resisted in their tendency to distort the sides of the culvertoutwardly, by such reinforcements at the top,

I. claim as my invention: f v

1. The method of increasing the supporting strength of conduits Ain trenchesor projected into filled areas, which consists in p `first forming in the earth a trenchhaving a. bottom surface and side walls, said bottom surface being formed to. receive and support precast conduits, then cutting into the earth in said bottom and sides of the earth trench wall forv the transverse depressions at the .side of the trench, and rfinally placing plas- U0 tic concrete material in the depressions and recesses at the bottom and sides of the conduit, said plastic concrete filling said transverse depressions and engaging both the earth at the bottom and sides lthereof andll the concrete at the top and innerface thereof. .f l

2. The method 4of increasing the supporting strength of conduits in trenchesor pro-` jected. into filled areas, which consists in l first forming in the earth a trench having abottom surface and side walls, saidbottom ,surface being formed to receive and support recast conduits, thencutting into the earth 1n said bottom and sides ofthe earth trench l a series of spaced transversely extended depressions, then placin a conduit in position i with portions thereo resting u on the bottoni of the trench which ha previouslyV been shaped to receive it, and other portions l.

1,s71,e79 y 3 thereof projecting across said transverse verse depressions and engaging both the 10 depressions, and whereby the conduit itself earth at the bottom and sides thereof and forms a -top for the transverse depressions the concrete at the top and inner face therein the bottom of the trench and an inner of, and then placing concrete material over 5 Wall for the transverse depressions at the the top portion of the conduit in line with kside of the trench, and iinall placing plasand Vforming a continuation of the concrete 15 i tic concrete material in the epressions and material in said depressions at the sides of recesses at the bottom and sides of the conthe trench. duit, said plastic concrete filling said transi ANSON MARSTON.

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