Abstract:
A manhole liner and a method of using the same are provided. The manhole liner is sized substantially equally to the largest diameter of the manhole, so that the liner does not have to stretch to be pressed against the manhole wall. Additionally, the liner is impregnated with a resinous material capable of curing and hardening. A bladder, preferably stretchable circumferentially and having a diameter less than the smallest diameter of the manhole, is inserted into the liner. The bladder is expanded to press the liner against the wall of the manhole to dispense resinous material from the liner, while the liner is able to fold over itself in areas having a diameter less than the original diameter of the liner. Because the bladder stretches to produce a smooth outside surface, the resinous material will migrate to areas in the folds and will cure with a smooth interior surface.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to a method and means of repairing a manhole. More particularly, but not exclusively, the invention relates to a method and assembly for lining a manhole wall. 
     BACKGROUND OF THE INVENTION 
     Conventional manholes include a lower or bottom pad, a barrel having a relatively constant diameter adjacent the pad, a concentric or eccentric cone extending upwardly from the barrel, one or more adjusting rings to adjust the overall height of the manhole, and a casting frame on top of the adjusting rings to support a lid at an elevation substantially level with the surrounding pavement. The casting frame is preferably sealed to the uppermost adjusting ring to preclude or minimize water flow into the manhole. 
     One problem with existing manholes is that many were made long ago, and then oftentimes were made of brick. Due to the old age of the manholes, as well as the materials used to make them, many manholes have begun to deteriorate or have damaged areas. The damaged areas create weak spots, which may allow water to infiltrate the sewer system and also lead to the eventual collapse of the manhole. 
     Methods exist for repairing the walls of manholes. One such method involves the use of a cured-in-place (CIP) liner with a polymer coating on its interior surface and a bladder to repair the manhole wall. The liner and bladder are placed in the manhole, and the bladder is expanded to press the liner against the manhole wall. The liner is impregnated with a resin and applied to the wall to create a new interior wall of the manhole. One problem with existing methods is the size of the liner used to line the wall of the manhole. The methods call for the use of a CIP liner and bladder having a diameter approximately equal to the smallest diameter of the manhole, with the liner being capable of stretching circumferentially to press against the manhole wall so to prevent the liner from wrinkling. However, some manholes require that the liner stretch up to and exceeding 150% of its unstretched diameter. This can cause the liners to rip, tear or be too thin, leaving the manhole wall not fully repaired. 
     Additionally, because the liners include an interior coating impervious to a resinous material, the liners cannot fold over themselves or bunch up because the liner wall would be formed with intermediate layers of material impervious to resin causing the liner to not be homogeneous across its thickness. 
     Accordingly, there is a need in the art for an improved method and means that overcomes the problem of a liner tearing while stretching circumferentially to press against the wall of a manhole. 
     BRIEF SUMMARY OF THE INVENTION 
     It is therefore a principal object, feature, or advantage of the present invention to provide an improved method and means for lining a manhole which improves over or solves the deficiencies in the art. 
     Another object, feature, or advantage of the present invention is to provide an improved method and means for lining a manhole wall that allows a liner to fold over itself and to bunch up while still producing a smooth interior wall. 
     Another object, feature, or advantage of the present invention is to provide an improved method and means for lining a manhole wall wherein the diameter of the liner is sized to be larger than the smallest diameter of the manhole. 
     Another object, feature, or advantage of the present invention is to provide an improved method and means for lining a manhole wall wherein the diameter of the liner is sized to be substantially equal to a largest diameter of the manhole. 
     Another object, feature, or advantage of the present invention is to provide an improved method and means for lining a manhole that uses a liner to transport a resinous material capable of curing and hardening into a manhole. 
     Another object, feature, or advantage of the present invention is to provide an improved method and means for lining a manhole that uses a bladder capable of stretching circumferentially to press the liner against the wall of the manhole. 
     Another object, feature, or advantage of the present invention is to provide an improved method and means for lining a manhole that uses a liner for containing a resinous material capable of curing and hardening. 
     Another object, feature, or advantage of the present invention is to provide an improved method and means for lining a manhole that can be used in manholes having varying diameters along the height of the manhole. 
     These and/or other objects, features, and advantages of the present invention will be apparent to those skilled in the art. The present invention is not to be limited to or by these objects, features and advantages, and no single embodiment need exhibit every object, feature, and advantage. 
     According to one aspect of the present invention, a method of lining a manhole having varying diameters along its height is provided. The method includes taking a manhole liner having a tubular shape and an unstretched diameter larger than a smallest diameter of the manhole. The liner is impregnated with a resinous material capable of curing and hardening. The liner is positioned in the manhole, and a bladder is inserted into the liner. The bladder is then expanded to press the liner against the wall of the manhole, with the liner folding on itself along a portion of the liner. The resinous material is allowed to cure and harden to produce a smooth finished surface, including along the portion of the liner folded on itself. Finally, the bladder is removed from the manhole. 
     According to another aspect of the present invention, a method of lining a manhole having varying diameters along the height of the manhole and having a largest diameter near the bottom of the manhole and a smallest diameter near the top of the manhole is provided. The method includes taking a manhole liner having a diameter substantially equal to the largest diameter of the manhole. The liner is impregnated with a resinous material capable of curing and hardening, and then positioned in the manhole. An inflatable bladder capable of stretching circumferentially is inserted into the liner. Next, the bladder is inflated to circumferentially stretch the bladder to press the manhole liner into contact with the wall of the manhole. The liner is folded over itself along an upper portion of the manhole. The resinous material is allowed to cure and harden against a substantially smooth surface of the bladder, and then the bladder is removed from the manhole. 
     According to yet another aspect of the present invention, a liner assembly for lining a manhole having varying diameters along the height of the manhole, with the largest diameter near the bottom of the manhole and the smallest diameter near the top of the manhole, is provided. The liner assembly includes a bladder and a manhole liner. The bladder comprises a first end, and opposite second end, and a bladder body there between, wherein the bladder body has a diameter smaller than or equal to the smallest diameter of the manhole. The bladder is also capable of stretching circumferentially. The manhole liner comprises a manhole liner body along its height, with the manhole liner body having a diameter substantially equal to the largest diameter of the manhole. Additionally, the manhole liner is impregnated with a resinous material capable of curing and hardening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of an exemplary structure of a manhole. 
         FIG. 2  is a sectional view of the liner assembly of the present invention positioned in a manhole. 
         FIG. 3  is a top sectional view of the manhole of  FIG. 2  according to line  3 - 3  of  FIG. 2 . 
         FIG. 4  is a view similar to  FIG. 2  showing the bladder fully inflated in the manhole. 
         FIG. 5  is a sectional view according to line  5 - 5  of  FIG. 4 . 
         FIG. 6  is a sectional view of the repaired manhole after the bladder has been removed. 
         FIG. 7  is a sectional view according to line  7 - 7  of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a sectional view of an exemplary structure of a manhole  10 . The manhole  10  includes a bottom floor  12 , a barrel  16  above the bottom floor  12 , a cone  18  supported by the barrel  16 , and a plurality of adjusting rings  20  supported by the cone  18 . A casting frame  22  resides upon the upper most ring  20  and supports a lid  26 . The casting frame  22  is normally sealed to the top ring  20 . It is understood that one or more rings  20  may be used to adjust the height of the manhole  10  such that the lid  26  is substantially at the level of the pavement  66  surrounding the manhole  10 . Also, while  FIG. 1  shows the cone  18  to have a concentric shape, it is understood that an eccentric cone can be utilized such that the manhole  10  has an asymmetrical cross-sectional appearance.  FIG. 1  also shows an optional run through  14  in the bottom floor  12 . While each manhole generally has unique size and shape, it is generally understood that the basic construction of the manhole  10  is similar in all manholes. Although manholes comprise varying diameters D 1 , D 2 , D 3 , and D 4  along the height of the manholes, the manholes generally are narrower at the top section, or chimney, than at the bottom section. Additionally, bricks  72  generally form the wall  24  of manholes. 
       FIG. 2  is a sectional view of the liner assembly  30  of the present invention positioned in a manhole  10 . The liner assembly  30  includes a bladder  32 , a manhole liner  42 , and a base  68 . The bladder  32  comprises a first end  34  attached to the base  68  near the opening  28  of the manhole  10 , a second end  36  positioned at the bottom  58  of the manhole, and a bladder body  38  there between. The first end  34  of the bladder  32  may be attached to the base  68  outside of the manhole  10  as well. The diameter  40  of the bladder  32  is preferably less than or equal to the smallest diameter D 1  of the manhole  10 . However, the bladder body  38  is stretchable such that it is able to press against a wall  24  of the manhole  10  when expanded. The manhole liner  42  is attached at the opening  28  of the manhole, and comprises a manhole liner body  44  that at least partially surrounds the bladder body  38  in the manhole  10 . 
     The manhole liner body  44  is comprised of lining material substantially free of coating or intermediate layers of material impervious to the resinous material  48 . The resinous material  48  may be a thermoset resin, which saturates the liner and cures and hardens quicker in the presence of heat. However, it should be appreciated that other resinous materials may be used, on the condition that they are able to cure and harden. The manhole liner  42  is essentially a transport device, such that the resinous material  48  forms the structural properties of the liner when cured. 
     The diameter  46  of the manhole liner  42  in one preferred form is sized substantially equal to the largest diameter D 1  of the manhole  10 . Therefore, the manhole liner  42  does not need to be stretchable. After the manhole liner  42  has been impregnated with a resinous material  48 , the manhole liner  42  is positioned in the manhole  10 . The bladder  32  is then inserted into the manhole liner  42 .  FIG. 3  is a top sectional view of the manhole  10  of  FIG. 2  according to line  3 - 3  of  FIG. 2 .  FIG. 3  shows the bladder  32  and the manhole liner  42  positioned in the manhole  10 . As is seen in  FIG. 3 , the diameter  40  of the bladder  32  is less than the diameter  46  of the manhole liner  42 . As is also shown in  FIG. 3 , the original diameter  46  of the manhole liner  42  is substantially greater than the diameter D 3  of the manhole  10  at the adjusting rings  20 . Because the diameter  46  of the manhole liner  42  is greater than the diameter D 3  of the adjusting rings  20 , the manhole liner will fold over itself and bunch up to fit within the top section  60  of the manhole  10 . 
     In another preferred form, the diameter  46  of the manhole liner  42  is sized larger than the smallest diameter of the manhole  10 . Here, the manhole liner will again fold over on itself and bunch up to fit the smaller diameter portions of the manhole  10 . 
       FIG. 4  is a sectional view similar to  FIG. 2  showing bladder  32  fully inflated in the manhole  10 . The bladder  32  is inflated with fluid pressure (not shown), such as air, introduced to the cavity  70  of the bladder body  38 . The increased pressure causes the stretchable bladder body  38  to expand circumferentially towards the wall  24  of the manhole  10 . The expanded bladder will press the manhole liner  42  against the wall  24  of the manhole  10 . This will create a layer  64  of resinous material  48  between the manhole liner  42  and the bladder body  38 . Because the bladder  32  has stretched circumferentially against the manhole liner  42 , the bladder body  38  will have a smooth surface abutting the layer  64  of resinous material  48 . This ensures that the resulting, manhole wall  24  will be smooth. 
       FIG. 5  shows a top sectional view of the manhole  10  of  FIG. 4  according to the line  5 - 5  of  FIG. 4 .  FIG. 5  is a sectional view of the manhole  10  near the top section  60  of the manhole  10 , where the diameter D 3  of the manhole is substantially smaller than the diameter D 1  of the bottom  58  of the manhole  10 . Because the manhole liner  42  has been sized substantially equal to the diameter D 1  of the larger section of the manhole  10 , there will be excess manhole liner body  44  at this upper section. The excess manhole liner body  44  will fold over itself and bunch up to create folds  52  in the liner. However, because the manhole liner  42  does not contain a resin impermeable coating, the folds  52  will compress and resinous material  48  will form a manhole liner  42  in the same way as in the bottom section, where the manhole liner  42  is a single layer. The compression creates a layer  62  of resinous material  48  between the manhole liner  42  and the bladder  32 . The thickness of the layer  62  of resinous material may vary according to the number of folds  52  or bunches in the manhole liner  42 . However, because the bladder  32  was stretched to press the manhole liner  42  against the wall  24  of the manhole  10 , the bladder  32  will have a smooth surface  56  pressed against the varying layers of resinous material  48 . This will result in the resinous material having a smooth interior surface. Because the folds  52  contain two or more layers of manhole liner  42 , the resinous material  48  will cure and harden to produce a thicker wall  24  of the manhole  10  at the top section  60  of the manhole. However, because the top section  60 , including the cone  18  and adjusting rings  20  (the chimney), of the manhole  10  undergoes the most stress and usually contains the most damage, the resulting thicker wall  24  will be stronger to help resist cracking due to freezing and thawing. 
       FIG. 6  is a sectional view of the manhole  10  after the resinous material  48  has cured and hardened and the bladder  32  has been removed from the manhole  10 . The bladder  32  may be removed by deflating the fluid from the cavity  70 , and then by pulling a rope (not shown connected to the second end  36  of the bladder  32 . Pulling the bladder  32  out by the bottom first causes the bladder  32  to peel away from the cured resinous material  48 . Although peeling the bladder  32  requires the least amount of effort, it should be appreciated that the bladder  32  may also be pulled straight out of the manhole  10  from the first end  34  of the bladder  32  as well. After the manhole lid  26  is replaced on the casting frame  22  of the manhole, what remains is a manhole  10  having a repaired and structurally renewed wall  24 . As is shown in  FIG. 6 , the manhole liner  42  has compressed the impregnated resinous material  48  from the manhole liner body  44 , creating a cured resinous material layer  62  around the interior periphery of the manhole  10 . As stated above, the layer  62  will be thicker in the top section  60 , or the chimney, of the manhole  10  because the manhole liner will have folded over itself. The thicker layer aids the section most affected by the elements, however. The folds  52  will occur in areas of the manhole  10  having a diameter less than the largest diameter D 1  of the manhole  10 . 
       FIG. 7  is a top sectional view of the manhole  10  of  FIG. 6  according to the line  7 - 7  of  FIG. 6 .  FIG. 7  shows that although the manhole liner  42  folded over itself, the manhole liner  42  was compressed against the smooth outer surface  56  of the bladder  32 , such that the interior periphery of the resinous material  48  cured into a smooth finish  50 . At the upper section of the manhole, the folds  52  of the manhole liner  42  will cause the cured resinous layer  62  to be thicker than at the bottom of the manhole  10 . However, because the bladder  32  is pressed against the manhole liner  42  with even pressure, the layer  62  of resinous material  48  will be substantially equal at a given height around the interior of the manhole  10 . The resinous material  48  will migrate from the liner to fill low areas of the liner, formed due to the folds, to create a resinous surface that is smooth about the interior periphery of the manhole  10 . The smooth finish  50  of the cured resinous material  48  allows the manhole to be used as it had previously before it required repair. 
     The invention has been shown and described above with reference to preferred embodiments, and it is understood that modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention. The invention is only to be limited by claims appended hereto.