CA2040666C - Continuous structure forming method and the resulting product - Google Patents

Abstract

A method of continuously forming an extended length of a unitary structure includes the following steps.
A supply of a porous flexible blanket is provided.
A high viscosity flowable solidifiable mixture is con-tinuously flowed simultaneously into an entire contin-uously moving width of the porous flexible blanket.
Pressure is applied against the treated blanket to form a uniform matrix therewith. The rate of advance of the blanket is monitored. The rate of alliance is co-ordinated with the flow rate of the mixture into the blanket and with the pressure applied thereto: A sub-stantially flat non-porous flexible envelope is posi-tioned along the length of the treated blanket. The envelope/blanket combination is positioned along a de-sired path. A pressurized gas is introduced into the envelope. The envelope is inflated to move the treated blanket into a final configuration, The non-porous envelope maintained in an inflated state until the treated blanket is set in the final configuration.
Also a unitary structure formed according to the above method.

Description

COiflINUJUS STRUCfU:E'~E FOi~.hI:LNG i~'i:~TIaOD
AND '1'ItE RESULTING ~'FtODUCT
'This application is a continuation-in-part of pending application 8~rial No. 41,501, fil~d October 5, 1989, which in turn is a oontinuation-in-part of application i3srial No. 235~205~ filed August 23' 198~, now U.B. Patont No. 4~872'~84.
r ~~~.s/t ~;fc~~ 3 ~j ,~a, ~F i3~~/5...~__ This invention relates to a novel mobile structure forming method and to a new continuous structure pro-duc~d thereby:
In recent years, the management of natural resour-ces hae~ beoome important in many countries throughout tha world: Efforts have been directed both toward the conservation of our resources and toward the elimina-tion of pollution from our environment. Particular emphasis has been placed on waste leakage and water loss.
for example, los~ees in the transfer of water using unlined ditches axe ~stimated at a minimum to b8 256 and in some situations to be more than 50;~ depending upon the porosity of the ditch surface and the distance the water is being moved. In most rural areas, ditches are farm~d by excavating the soil to the desired depth and Width. The water moves through the ditch in contact with the expos~d natural surface. This can beg sand, clay, rocks etc. and more commonly mixtures thereof.
fhe porosity will depend upon the proportions of the different components.

zo4osss While such ditches have beon used in the past, the results were considered acceptable only becau~o the supply of water exceeded the needs. AoWOVerf as civilization developed and world population increased, more water was required both for greater food produc-tion and for the marked increase in non-agriculture uses. In addition to greater domestic uses in sanita-tion, industry now employs large guantities of water in manufacturing and gracessing procedures.
This high 1~vel of consumption plus the very high coat of developing new water supplies has shifted at-tention to water conservation. Domestic appliances that use less water have been developed: Also, indus-try has installed recycling purification systems to reduce water consumption:
Although conservation efforts have reduced water consumption to a degre~, water still is in relatively short supply, particularly in recent years with the severe droughts in the United States and other countries.
Since the moat coat effective conservation opportunities and most readily aaceseible water supplies already have been developed, greater attention must be directed to improving the efficiency of water distribution systems.
Some improvements in water distribution already have been made. A limit~d number of ditches, canals and similar structures have been formed with placed concrete and/or preformed concrete units. Concrete is durabl~ and has a long life when properly used.
_2_ How~vgr, concrete is expensive to place and finish and ie damaged by depressed temperatures during curing.
Also, concrete is subject to frost damage, cracking and heaving which results in leaks.
PYC (polyvinlycHloride) structures also have been used to some extent in water distribution systems.
PVC is leas costly than concrete. The limited durabil-ity of PVC can be improved to a degree by burying it under s~veral f~et of sail. The sail holds th~ struc-ture in place and cushions it against damages However, both with concrete and PfC, considerable nits prepara-tion is required and after placement extra grading and filling fr~quently are needed to finish the fob.
From the above discussion, it is clQar that nei-ther concrete nor PVC provide the desired charactsri$-tics for successful liquid distribution and storage, that ia, durability, low cost and ~asy placement. Thus, there is a need for a new structure that provides these requir~m~nte~
The present invention provides a novel method and product which overcome the deficiencies of previous expedients: The invention not only overcomes those shortcomings, but al8o provides features and advantag~s not found in previous technologyy The method of the invention produces a uniform quality structure contin-uously and quickly with a minimum of base preparation and a short downtime even at low temperatures. The structure ie formed and placed with little hand labor.

With the method of the invention, the configuration and composition of the structure can be modified along its length as desired automatically to provide special configurations far spillways, headgates, changes in direction and the like.
Mobile apparatus for producing the novel struc-ture according to the method of the present invention is simpl~ in design and can be produced r~latively in-expensively. Commercially available materials and com-ponents can be utilized in conventional fabricating procedures in the manufacture of the apparatus. ~emi-skilled workmen can operate the apparatus efficiently after a minimum of instruction. The apparatus is dur-able in aonatruction and has a long useful life with little maintenance.
The method of the invention can be modifi~d to form a vari~ty of different structures. Variations in phy$ical dimensions, composition and surface appear-ance, etc. can be achieved quickly. Even with such variations, uniform quality is maintained without dif-f iaulty.
These and other benefits and advantages of the novel method and product of the present invention will be apparent from the following description and the ac-companying drawings in whichs 2U~0666 F"figure 1 is a schecaatic illustration of one em-bodiment of thp method of the invention;
Figures ?9 3 and rE ara c3~os:~-sect3.ona1 illuetra-tions during an inflation st~:p of the method of thQ
invention;
Figure 5 is a cross-sectional i:Llustration dur-fins a tub~ forming step of tr~~ raQthod of the invention;
Figure 6 is a crass-sectional ill~a:~tration durin a tube folding step of the method of the invention;
Figure 7 is e. oros$-~sectionr~:t illustration during the forming of another structure of the invention i Figure 8 is a cros3--sectional illustration during the forming of a further structure of the invention;
figures 9 and 10 are long~.tudinal sectional il-lustratione during the farming of an additional etruc-tore of the invention; and Figure 11 is a vioYr in perspective of one form of apparatus for conducting, the method of the invention.

As shown in Figures 1 - ~: of the drawings, one embodim~nt of the novel method of continuously forming an ~xtended length of a unitary mtructure of the pres-ent invention includes providing a supply of a porous flexible blanket 11. A high viscosity flowable salid-ifiable mixture 12 disposed in a trough, l3 is continu-ously flowed uniformly simultaneously into an entire continuously moving width 14 of the porous flexible blanket. Pressure is applied against the treated blan-ket 15 to form a uniform matrix 1~ therewith. The rate of advance of the blanket i$ monitor~d and coordinated with the flow rata of the mixture 12 into the blanket and witb the pressure that is applied to the blanket such ae by rollers 18.
A substantially flat non-porous flexible envel-ops 19 is positioned along the length of the treated blanket 15. In Figure 1, the non-porous envelope 19 from a roll 20 thereof is continuously fed with the moving treated blanket 15.
The oombination 22 of th~ envelope and the blan-ket then is positioned along a desired path. Ae shown, the combination ie pulled through a culvert 23 with a winch 24. To facilitate positioning of the combina-tion, a transport sheet 26 advancing from a supply roll 27 to a take-up roll 28 may be utilized.
When a desired length of the envelope/blanket combination is properly positioned within the culvert 23, the onds of the envelope are sealed except for an ~5_ 20~066E
inlet (not shown) through which a pressurized gas is introduced into the envelope 19.
As the envelope inflates, the blanket therewith is moved to a final configuration, that is, in contact with the inside surface 29 of the culvert 23. pigures 2 - 4 illustrate different stages of the inflation.
Continuous contact of the blanket with the inter-ior of the culvert is maintained with the inflated en-velape until the structure is set in its desired con-figurations Thereafter, the envelope is deflated and withdrawn, if desired, leaving a structure permanently set in contact with the culvert. Th~ blanket provides a continuous unitary structure 30 within the culvert.
The structure 30 can be a solid shell or an oper_ cov~ring as desired depending upon the construction of the porous blanket 11 employed as the starting ma-terial. A blanket may have tight or loos~ construction and advantageously is a fabric, preferably formed with interconnected discontinuous fibers. 'then a continu-ous matrix is formed within a relatively dense blanket, the structure can provide a water tight seal as well as considerable strength.
The strength of the structure can be increased by utilizing multiple blanket layers 11, 31 and 32 in-itially Figure 1). Longitudinal or transverse strength members or both also u~ay be included within the blankets.
Tn situations in which the passage of wet~r therethrough zo~ossE
is desirable, the starting blank~t can bo of a net or mesh construction with an open matrix network along the elements of the blanket as will bs discussed here-inafter.
Advantageously, to provide a cylindrical config-uration such as a culvert liner., the long3.tudinal edges 33 and 34 of the treated blanket 1~ are arranged around the flat non-porous envelope 19 to form a flattened tubular blanket 35. This can be accomplished by passing the envelops/blanket combination 22 through a folding mechanism 3~ such a~f eur!~ed panels 38 arid 39 in Figure 5. ~'or the lining of tanl~a or p3.pin~, with limited size access openings, the combination can be folded addition-ally (figur~ 6) with a curved panel 40 to r~duce the cross-sectional wise to fit small access apening$ while still providing large expansion capability.
To simplify formation of a continuous high strength liner, it is preterred that the longitudinal blanket edges 33~ 34 be arranged in an overlapping relationship with the initial overlap being sufficient to retain the overlap 42 throughout expansion of the treated blan-ket into tighb contact within the restraining outer struoture. Advantageou~ely, the longitudinal edges should be capabl~ of slipping with respect to one another dur-ing the expansion but remain adhesive for good final adhesion therebetween.
~fhen it is des~ir~d to provides liners of larger diameter than is obtainable with a single width of a _g_ blanket, a number of mixture treated blankets 45, 4E~, 47 may be assembled side by side with their longitudi-nal edges 48 and 49 in an overlapping ed6e to edgQ re-lationship as shown in figure ;. The assembly then can be combined with a single large inflatable envelope 50 and the free edges 51, 52 of the ass9mbly wrapped around the envelop~ and overlapped to form a Flattened tube.
Altsrnatively, a singl~ treated blanket strip can be positioned on a deflated envelope and the envel-ope inflated to place the strip in contact with the inner surface of the structure bei ng wavered. After the first strip has set and adheres tightly to the struc-ture, the envelope is deflated. A second blanket strip then ie positionr~d in an adjoining position on the en-velope and the envelope reinflated to place the second strip in contact with the innor surface of the struc-ture in an overlapping relationship with the initial stripy These steps are repeated with succeeding blan-l~et stripe sequentially until the structure is complete.
Multi-blanket structures can be formed of blankets hav-ing substantially the same or different porosities and constructions as desired.
The solidifiable liquid mixture applied to the blanket in the method of the invention advantageously includes a resin forming component and preferably is a thermosetting resin forming mixture such as a poly-ester or polyurethane forming mixture. The mixture also may include catalysts, fillers, particulate reinforce-ments and the like.
-g-'fha above method of sequentially applying indi-vidual blanket strips positioned on an inflatable en-velope may be utilized in the stabilization or reinforc~s-mant of surfac~e located in a single plane such as walls, ceilings, inclined surfaces and the like. For example, a~a shown in Figure 8, a freshly treated mesh blankot 55 is applied to an inelin~d rocl~ wall 5E~ and intimate contact achieved and maintained during getting by pre~s-~aure from an inflatable envelope 57. The resulting structure prevents rocks from sliding onto a highway and creating a traffic hazard.
The method of the invention also is useful in forming a diaphragm in a conduit for reducing or stop-ping tbs flow therathrough. In this construction sho~,nn in Figures~9,lQ,a non-porous flexible envaiopa section 61 of less~r width than an extended length of a treated blanket 62 and of a~.,ahort length is placed on the blan-k~t. The envelope is covered with a somewhat larger discrete blanket section 63 that has been treated with a solidifiable liquid mixture that will form a flexible matrix and preferabl9 an elastic matrix. The trQated blanket section is generally centered over the envel-op~ section 61 with the outer edge of the blanket sec-tion 63 in contact with treated blanket 62.
Advantageously, an inlet fitting f.;4 is positioned to extend through the length of treated blanket to pro-vide access to the envelope section 61 for inflation thereof. The envelope section is inflated through fit-ting 64 causing the blanket seotion 63 to expand into 2040~GE
the conduit interior to form a diaphragm ~~~ whioh is capable of blocking all or a part of the conduit to stop or reduce tho flaw of liquid tharathrough. Upon release of the pressuro within the envelope section, the diaphragm ~5 retracts to its Ur,i~;ina1 position close to th~ conduit wall to allow the liquid to flow norma115 through the conduit.
If desired, a number of diaphragms can be loca-ted periodically along the length of a conduit adjacent spaced outlet openings snot shown) to divert water into side channels for irrigation or othor similar purposes.
Also, a conduit may bs foz~med with a solid lower blan-ket and an open mesh upper blanket with the water spil-ling over the edge of the lower blanket as the diaphragm is raised.
Une form of mobile apparatus ~0 for producing the above nov~1 structure according to the method of th~ pr~aent invention as ahawn in Figure ~1 includes base sections 71 and 72: Advantageously, one of the base s~ctions is adjustably connected to the other, preferably with a connection providing ad~uetment with respect to both spacing and orientation. As shown, the base sections are adjustably interconnected through a telescoping boom ~~ with pivoting connections ~~ and ~5~
The base section ~2 may bm part of an enclosure suoh ae pod 7~ in which a number of components are lo-cated. For examplo, blank~t supply means ~8, mixing means '~9 and matrix forming means 80 are locatod wi~th~.n pod ~r~
The raw materials are stared in a plurality of reservoirs 81' 82, 83 and 84 as required. The reser-voirs may include resin components, catalysts, fillers, particulate reinforcements' other additives and the like. The reservoirs are connected independently with mixing means 79 through flexible conduits 8Ep 87! 88 and 89. An independent bypass return conduit prefer-ably extends from an and of each conduit 80 - 89 ad~a-cent ttze mixing weans ~9 back to the respective reser-voir.
Blanl~et support means 91 which extends from thg base section 22 advantageously accommodates a signifi-cant length of one or more continuous porous blankets on rolls 92 in a dispensing orientation. Suitable por-ous blankQta include woo~n~ t~nit~ non-woven struature9' etc. The blankets, e.g, fabrics4 mats, etc. may be formed of continuous or die~continuoua fibers, yarns, slit ribbons and the like. If desired, reinfoxcing members such as ropes cables and the like that extend longitudinally and/or transvers~ly of the blank~t cen-terline may be included.
The mixing means 79 of the apparatus ~0 includes an elongated chamb~r 93. The chamber 93 ie mounted on the base section 72 adjacent tihe matrix farming means 80. A plurality of deft~ctor aection~ (not shown) may be disposed within the mixing chamber 93 spaced along the le:n~;th of the chamber. Th~ deflector sections ad-vanta~;eously ax~e angled with resp~ct to ~z longitudinal axis Of ti~o elon~atEd ~~tiamber.
The matrix forming means 80 of toe apparatus 70 includes elongated ~tia.ture delivery means scaown as tro~tr~:~
~4;, Tlue mixture delivory means is disposed closely ad-~acent to t«ct mixing claambar 93. Ira mixture d~li_very means is disposed substantially parallel to tt~e blan-ket roll' that is, substantially perpendicular to t2~e line of r~ovement of the blanket.
The matrix forming means 80 also includes proseure applying means disposed adjacent t~-ze mixture d~livery txough 94. The pressure applyi.n~ means advantageo~lsly includes at least one pair of cooperating aligned rollers 95. The pod 77 preferably includet~ envelops supply means 105 folding means 1~5 and cutting; means (not shown).
The control portion of tha apparatus s~0 includes a plurality of pumps, valves sensors, monitors and the like. Advanta~eously~ a pucup 96s a valve 97, and a flow monitor 98 are locat~d along the len~,th of each conduit X36 - 89 that extend~a b~tween thc~ raw material reservoirs 81 - f34 and the mixing chamber 9>.
The control portion also includeB drive means.
A first drive advancos a continuous porous blanket through the matrix forming portion E30. A second drive ie used for telescoping boom 73 and for tha movement of the apparatus 70 around the fob site.
_13-'.the pumps valves, drives and other components are cantrollmd by actuating m~ans 100 that is respon-sive to information from the flo~~r monitors and other sensors. fhe actuating means also is responsive to instruction~t from programmable memory means 7.01. '~~he pumpsi valves, drives etc. of the contro'1 portion pre-f~rably include electrical motore~.
Advantageously, the control port~.on includes co-ordinating means 102, preferably inrludin~; r~ process controller 103. The process controller initiates changes in th$ flows of materials and speeds of drives to bring variations therein back to the rates epecifiQd in the program present in the memory meaner This coordination commonly is achieved through th~ transmission of infor-mation as digital pulses from thc~ monitors and/or sen-sory at the components to th~ process controller 103.
the operating information is compared with the pres~-lected programming parameters stored in the memory.
If differences are detected, instructions from the con-trallar change the operation of the components to re-store the forming operation to the preselected process specifications Novel continuous structures of the prassnt inven-tion may be formed using the mobile apparatus 70 shown in Figure 11 employ-ing the followin6 steps of the method of the invention. After the design of the struc-ture has been ~etablished, the process param~tera for the particular design being formed e.re programmed into the memory 101. which may be a computer. Then, the -1~+-2040~f 6 apparatus is moved to th~ location at which the struc-ture is to b~ formed.
To begin the methods appropriate buttons and/or switches on control panel 104 are depressed to activate thQ second drive to move pod ~Ti into positj.on by maneu-vering boom ~3. The depression of the button~a and/or switches also has activated memor~~ means 101, actuating means 100, coordinating means 102 and the other compo-nents of the control portion. The pumps 9~~ valves 9 and flow monitors 98 are energized in the preselected sequences of the memory. Th3a causes 'the raw materials stared in reservoirs 81 ~ 84 to advance along the re-~apective conduits 86 - 89 toward the mixing chamber 93.
The delivery of raw materials to the mixing cham-ber 93 will vary depending upon the particular formu-lation and quantity thereof required for a specific incremental area of the structure being formed at that moment. Although the flows through the conduits into the mixing chamber will vary, it is important that the raw materials entering the mixing chamber maintain a uniform quality such as by including for each conduit a bypass that extends from the end of the conduit ad-~acent the mixing chamber back to the respective reser-voir.
The control portion coordinates the operation of th~ various system components eo the required for-mulation in trough 94 flows into the blanket passim, therethrough. The blanket then passes between pressure rollers 95 which compress the impre~,nated blan:~:et to worn the salidifiablQ mixture into the interstices for uniform distribution thereof to achieve a coatrix within the blanket. Tlae rasultin~; product ig immediately po-sitioned while the matrix is adhesive and capable oz tightly bonding after combination witla.the envelope.
The formation ni' the navel structures accordin~~;
to th~ above method can b~ completed c~uiclcly with a minimum of labor. Also, areas along the length of the structure can be customized automatically to provide the features required for spillway's, headgates, CllaTyf~es in direction and the like. '.the structure is permanent-ly formed to the configuration of the restraining sur-face and is firmly anchored thereto. The liner is dur-able and resistant to damage from impact, .frost, settling of the base and the li'..~e.
Uther forms of apparatus for producing the novel structure according to the method of the invention may include a boom with multiple pods arranged to provide succeeding ovorlappin~; blankets. Since the blan~ets axe adhesive, the ad;joinin~; blankets adhere tightly to Qach other and form a continuous surface.
Other suitably apparatus may include a pod which is dispos~d along a centerline of th Q apparatus. Ap-paratus suitable for long straight runs may include a cart including a pod and a raw material supply that ie pulled forward with a cable and winch positioned at the opposite end of the run.

The above description and the accompanying; dracn-ings show that the pres~nt invention providaa a novel method and product with features and advantages not known previously; The structure is formed, placed and set easily and efficiently with a minimum of supQrv~~.s-ion and labor and without special er.,u~.pm~nt c~x~ procedures.
The resulting structure is h~.gh 3.n ~;t:rnn~;th and ?.~.aw in cant.
The configuration and compaeition of the struc-ture can be modified along its length automatically to meet the rec?uirements for spillwa;~ s, haadgates~ cG~an~;es in direction and the lixe. The structure is s~t in the configuration of the restraininJ surface and anchored to 'the underlying base. The stricture is durable and has a long useful life without maintenance or repair.
The base surface requires little' if any, prepar-ation before the structure is ??.aced. The structure can be placed at depressed temperatures not suitable for concrete placement.
The method of the invention permits a large va-riety of different structures to be produced. Changes from one design to arxother can be cease easily and quickly.
It will be apparent ttzat various modifications can ba made in the particular method and product described in detail above and shown in the drawings within the scope of the present invdntion. '.Che arrangement of steps and types of materials can be changed tc r~eet 204~6~6 specif is roc~viraments. 'these and other changes can be made in tha method and product provided the func;t--ionin~ and operation thereof are not adc~oxae~ly affected.
'therefore, the sco~ye o:E the presort invention is to be limited only by the; following r.la~irns.
_I8_

Claims (29)

1. A method of continuously forming an extended length of a unitary structure at a job site including the steps of providing a supply of a porous flexible blanket, providing a plurality of thermosetting resin forming raw material reser-voirs, advancing each raw material independently to mixing means disposed closely adjacent to mixture delivery means, mixing said raw materials in preselected proportions, immedi-ately continuously flowing uniformly a preselected quantity of a high viscosity flowable thermosetting resin forming mixture simultaneously into an entire continuously moving width of said porous flexible blanket, applying pressure against said treated blanket to form a uniform matrix therewith, monitoring the rate of advance of said blanket, coordinating said rate of advance with the flow rate of said mixture into said blanket and with the pressure applied thereto, positioning a substantially flat non-porous flexible envelope along the length of said treated blanket, continuously positioning said envelope/blanket combi-nation along a desired path while said combination is deform-able and said matrix is adhesive, introducing a pressurized gas into said envelope, inflating said envelope to move said treated blanket into a final configuration against a support-ing surface, maintaining said non-porous envelope in an in-flated state until said treated blanket is set in said final configuration and bonded to said supporting surface.

2. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein a continuous matrix is formed within said porous blanket during application of pressure thereto.

3. A method of continuously forming an extended length of a unitary structure according to Claim 1 in-cluding arranging longitudinal edges of said treated blanket about said flat non-porous envelope to form a flattened tubular blanket and expanding said tubular blanket.

4. A method of continuously forming an extended length of a unitary structure according to Claim 3 wherein said longitudinal blanket edges are arranged in an overlapping relationship.

5. A method of continuously forming an extended length of a unitary structure according to Claim 4 wherein said tubular blanket is expanded while said longitudinal edges thereof are capable of slipping but remain adhesive, and an overlap is maintained between said edges.

6. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein said blanket is disposed along a base surface.

7. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein said blanket is disposed within a restraining structure.

8. A method of continuously forming an extended length of a unitary structure according to Claim 7 wherein said blanket is disposed within a conduit.

9. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein a plurality of said blankets are stacked prior to combining with said non-porous envelope.

10. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein a plurality of said blankets are assembled in an overlapping edge to edge relationship prior to combining with said non-porous envelope.

11. A method of continuously forming an extended length of a unitary structure according to Claim 10 wherein blankets having substantially the same porosity are assembled.

12. A method of continuously forming an extended length of a unitary structure according to Claim 10 wherein blankets having different porosities are assembled.

13. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein a blanket including open areas along said blanket is provided.

14. A method of continuously forming an extended length of a unitary structure according to Claim 13 wherein a blanket including open areas arranged adjacent one another along said blanket is provided.

15. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein a porous blanket having a tight construction is provided.

16. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein a porous blanket having an open construction is provided.

17. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein a porous blanket formed of a fabric is provided.

18. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein a porous blanket formed of interconnected discontinuous fibers is provided.

19. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein a porous blanket including spaced longitudinal strength members is provided.

20. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein a mixture including a polyester forming mixture is provided.

21. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein a mixture including a polyurethane forming mixture is provided.

22. A method of continuously forming an extended length of a unitary structure according to Claim 1 wherein a discrete non-porous flexible envelope section of lesser width than said blanket and of a short length is placed on said extended length of treated blanket and a discrete treated blanket section somewhat larger than said envelope section is centered thereover prior to positioning of said envelope/blanket combination.

23. A method of continuously forming an extended length of a unitary structure according to Claim 22 wherein a continuous length of treated blanket including an inlet fitting therethrough is positioned to provide access to said envelope section.

24. A unitary structure formed according to the method of Claim 1.

25. A unitary structure formed according to the method of Claim 4.

26. A unitary structure formed according to the method of Claim 7.

27. A unitary structure formed according to the method of Claim 9.

28. A unitary structure formed according to the method of Claim 10.

29. A unitary structure formed according to the method of Claim 22.