US 3438157 A
Description (OCR text may contain errors)
April 15, 1969 F. LA MONICA 3,438,157
UTILITY MANHOLE Filed June 25, 1967 Sheet of a INVENTOR F lgJ FRANK LoMONlCA ATTORNEY April 15, 1969 F. LA MONICA UTILITY MANHOLE Sheet Filed June 23, 19
April 15, 1969 F. LA MONICA UTILITY MANHOLE Sheet of 5 Filed June 23, 1967 Fig-5 United States Patent 3,438,157 UTILITY MANHOLE Frank La Monica, Avon, Conn., assignor to A. Rotondo & Sons, Inc., Avon, Conn., a corporation of Connecticut Filed June 23, 1967, Ser. No. 648,259 Int. Cl. E02d 29/14; E04l1 9/06; 1204b 5/48 U.S. Cl. 52--20 4 Claims ABSTRACT OF THE DISCLOSURE A utility manhole in the form of an assembly of three precast concrete sections comprising an upper section adapted to be lowered onto and supported by left and right lower sections adapted to be joined together after each is lowered into a prepared excavation to either side of an existing conduit extending through the excavation and containing electrical lines.
This invention relates to a precast concrete utility manhole having three assemblable sections; more particularly it relates to a manhole having an upper downwardly open box-like structure and precast left and right sections joinable together along a vertical plane to form a lower upwardly open box-like structure for supporting and forming with the upper structure a manhole.
Utilities must often break into existing lines to connect branch lines. To provide easy access to such branch connections for servicing manholes are built around them.
Prior practice has been to dig away the surrounding earth and build, brick by brick, a surrounding enclosure, or alternatively to set up forms and to pour concrete to form a surrounding enclosure. These methods are clearly time consuming and expensive. Precast concrete boxes formed of precast upper and lower sections have been advanced as well as precast structures with intermediate sections. Though these precast structures are improvements over formed in situ manholes they have not satisfactorily solved the problem where manholes must be installed around existing conduit inasmuch as, unless the conduit and all lines therein are cut and bent to accommodate the lower manhole structure, a hole must be dug which is wider by at least one and one half times the width of the lower half of the manhole whereby the lower half may be lowered down and moved laterally and centered beneath an existing conduit. In that these manholes generally have overall dimensions on the order of 7 foot wide and high and 15 feet long, the larger excavations required to accommodate the precast lower sections, tie up for longer periods of time machinery that might otherwise be gainfully employed. Further moving the great weight of a single piece lower section laterally, and manipulating to center it beneath existing conduit is also time consuming of labor and machinery. In addition, the location of existing conduit in restricted areas that do not permit the excavation of holes wide enough to place a single piece lower section beneath the conduit requires the utility companies to fall back on the older methods noted above.
In accordance with the invention, the disadvantages and shortcomings of prior precast manholes are overcome in the provision of a lower manhole structure comprising a left and right section joinable along a vertical plane. Each of these lower sections may be lowered straight down into a prepared hole that need be no wider than the combined widths of the left and right sections plus the width of the conduit which is to be enclosed. After the lower sections have been lowered provision is made to bolt them together. Thereafter the top or upper section, provided with cutouts to accommodate the passage of conduit is lowered and supported by the joined lower sections.
A feature of the invention resides in the fact that the left and right lower sections may be of different widths to permit installation around conduit which may be relatively close to an existing surface structure. Similarly the heights of the top section and that of :the lower sections may be equal or not as desired.
An object is to provide an improved precast concrete manhole structure which expedites and facilitates installation about existing underground conduit with a minimum expenditure of time and labor and without the necessity of cutting all lines therein.
Another object of the invention is in the provision of a utility manhole having three precast sections which permit installation in spaces restricted in area.
Still another object of the invention is in the provision of a lower manhole structure adapted to underlie existing conduit having two relatively light sections adapted to be joined along a vertical plane after being lowered into a prepared excavation wider than the width of the joined sections only by the width of a length of conduit to be enclosed.
Still another object of the invention is in the provision of a lower manhole structure adapted to underlie crossed conduits extending through an excavation comprising four sections joinable along vertical planes after being lowered into a prepared excavation beneath the conduits.
Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof and wherein:
FIGURE 1 is a partially cut away partially exploded perspective view of a precast concrete three piece utility manhole assembly in accordance with the invention;
FIGURE 2 is a partial cross sectional view showing the means for securing the left and right lower sections of the manhole;
FIGURES 3 and 4 illustrates the installation of the present concrete three section manhole comprising applicants invention;
FIGURE 5 is an elevational view of a modification for a particular installation wherein the conduit to be enclosed is close to an existing subsurface structure as to preclude centering; and
FIGURE 6 is a perspective view of another modification adapted to enclose crossed conduits.
Referring now to the drawings wherein like reference numerals designate like or corresponding elements throughout the several views and wherein a preferred embodiment is illustrated there is shown in FIGURE 1 a three piece precast concrete manhole assembly which comprises an upper downwardly open box-like section generally designated by reference numeral 11 which may be separately formed in a conventional mold which per se forms no part of the invention. The upper section 11 is provided with reinforcing steel rods 12 (FIGURE 1) spaced in top to bottom horizontal planes and end to end vertical planes extending around the corners of and within the top, side, and end walls 13, 14 and 15 respectively of the section. The upper or top wall is also formed with a manhole opening 16 and cover as is understood in the art. The lower structure of the assembly comprises a left and a right section generally designated by reference numerals 17 and 18 respectively having bottom, side, and end walls 19, 20, 21 respectively. These sections may be of the same width, i.e. quarter sections, or vary in width relative to one another as required for a particular installation as shown in FIGURE 5, wherein the conduit 30 is so closely adjacent a water or gas main M as to preclude centering the manhole about the conduit to be enclosed. Both sections 17 and 18 may be molded together in a mold similar to the upper section mold with a removable U-shaped steel spacer (not shown) placed in the mold about the mold core at any location intermediate the side walls of the mold core to maintain them separate during formation. Like the upper section 11, each lower section is reinforced by steel reinforcing rods 22 located in spaced horizontal and vertical planes; As viewed in FIGURES 1 and 2 the adjoining edges 23 and 24 of the end and bottom Walls of the left and right sections have complementary tongue and groove shapes as formed by the steel spacer so that mating fits are obtained when they are brought together and sealed by asphalt cement or an equivalent.
With reference to FIGURE 1 the left and right lower sections have internally threaded inserts 24 embedded in the end walls 21 thereof, whereby after formation, angle irons 27 may be secured, as by bolts 28, adjacent and parallel to the edges of opposite end walls of each of the lower sections.
With reference to FIGURE 3, there is shown an excavation 29 dug around an existing conduit 30 having cables 31 therein and to one or more of which branch lines (not shown) are to be connected. As evident, the width of the excavation need only be wider than the combined width of the lower sections 17 and 18 plus the width of the conduit 30. After the bottom of the hole is levelled the sections 17 and 18 are lowered straight down as indicated by arrows 32. Threaded inserts 33 (FIGURE 1) embedded in the top edges of the end walls 21 are provided to enable removable lifting bolts (not shown) to be secured. After lowering sections 17 and 18 in turn, they are moved laterally together as indicated by arrows 32, sealed by asphalt 25, and permanently bolted together as by bolts 34 extending between the angle irons 27. Thereafter a loW- ering hoist accommodated by gripping grooves 35 in the end walls of the upper section 11 is employed to lower the top section 11 atop and to seal it to the now joined lower sections as indicated in FIGURE 4. As viewed in FIG- URE 1 the lower edge of the upper section and the upper edge of the now joined lower sections have complementary flanged edges 36 and 37 respectively. In FIGURE 1 the end walls of the upper section 11 are provided with openings 38 extending upwardly from the lower edges thereof to accommodate the passage of conduit 30 therethrough. It is to be understood, however, that in particular installations the openings to accommodate the conduit ma be provided in the end walls 21 of either or both of the left and right lower sections or in one end wall of the upper section and in opposite end walls of the lower structure to accommodate conduits which slope from a horizontal. Knockouts may be formed in the end or side walls 14 of either the upper or lower sections at desired locations to accommodate branch connections to selected cables within the enclosed section of conduit 30 as understood in the art and either bottom wall may be provided with a sump pump knockout 40 as desired.
With reference to FIGURE 6 there is shown a modification to accommodate conduits 41 and 42 which cross one another at right angles. In this modification each of the left and right sections of the lower structure may be formed of two halves 43 and 44 joinable along a vertical plane intermediate the end walls 20 after being lowered into the quadrants formed by the crossed conduits, and the so joined halves forming the left and right sections being joinable to form a bottom structure. In such an in stallation openings 45 and 46 will be provided in the end and side walls of either the top or bottom structures to accommodate the conduit or in the end and side walls respectively of the top and bottom structures as shown.
While the above description has reference to electrical conduit, the disclosed structures may also serve to enclose branch connections to existing water or gas mains.
The invention claimed is:
1. A sectional precast concrete utility manhole adapted to be assembled to enclose existing underground conduit extending through a prepared excavation Whose width need be no wider than the combined width of conduit and assembly, said manhole comprising,
a single piece downwardly open box-like upper structure having a top wall and opposing side and end walls,
a left and a right section each having a bottom, a side, and opposing end walls, said sections being adapted to be lowered vertically bottom side down into said excavation on opposite sides of said conduit with the side walls outermost,
means for joining said sections together along a common vertical plane after laterally moving them together beneath said conduit with opposite edges of end and bottom walls abutting,
said joined sections forming an upwardly open boxlike bottom structure of dimensions corresponding to and for supporting and forming with said upper structure an enclosure,
and openings extending to the edges of opposite end walls of at least one of said structures forming the enclosure to accommodate the conduit extending therethrough.
2. A sectional utility manhole as recited in claim 1 wherein said means for joining said sections together comprises angle irons secured externally to the end walls adjacent and parallel to opposite vertical edges of the end walls, and bolts securing opposing angle irons together.
3. A sectional utility manhole as recited in claim 1 wherein the conduit to be enclosed comprises cross conduits and wherein each of said left and right sections comprise two halves joinable together along a common vertical plane at right angles to the vertical plane joining the left and right sections, and means for joining said left and right section halves.
4. A sectional utility manhole as recited in claim 3 wherein said top section side walls and said bottom structure end walls have openings to accommodate said crossed conduits.
References Cited UNITED STATES PATENTS 529,511 11/1894 Walker et a1. 52-492 X 684,708 10/ 1901 McFall 52-20 711,713 10/ 1902 Bolser 52 140 2,765,135 10/ 1956 Chellis 52125 X 3,263,378 8/1966 Dorris 52- X FOREIGN PATENTS 685,158 12/ 1952 Great Britain.
ALFRED C. PERHAM, Primary Examiner,