SEGMENTED BULKHEAD FOR TUNNELS AND THE LIKE
United States Patent 3578752
A circular bulkhead is formed of a pair of segments and is capable of assembly and erection within the confines of a tunnel. The generally semicircular segments include means for joining the segments together to form the completed bulkhead.
US Patent References:
Head-locking mechanism for containers
Wood et al. - December 1930 - 1783687
Prestressed concrete pressure vessel for nuclear reactors
Ziegler - June 1968 - 3389516
Head-locking mechanism for containers
Wood et al. - December 1930 - 1783687
Prestressed concrete pressure vessel for nuclear reactors
Ziegler - June 1968 - 3389516
Application Number:
04/761770
Publication Date:
05/18/1971
Filing Date:
09/23/1968
View Patent Images:
Export Citation:
Assignee:
Milwaukee Boiler Manufacturing Company (Milwaukee, WI)
Primary Class:
Other Classes:
405/133, 405/144
International Classes:
E21D11/00; E02D23/00
Field of Search:
61/83,63 52/19,20,21,208,213 220/55 (A)/ 220/55 (B)/ 220/3 114/44,78 138/(Inquired) 215/(T.H) 285/(T.C) 277/(Inquired)
Primary Examiner:
Taylor, Dennis L.
Claims:
I claim
1. A circular bulkhead formed of a pair of segments and capable of assembly and erection within the confines of a tunnel, said tunnel having a tubular liner of circular cross section and a ring secured to the interior of said liner at a predetermined location therealong, said ring having sides extending inwardly from said tunnel liner and defining pressurizable and unpressurized portions of the tunnel, said circular bulkhead being parted along a line forming a chord thereof to define said pair of segments, each of said bulkhead segments including a generally semicircular, pressure resisting wall portion having a peripheral edge and a straight parting edge lying on said chord, said peripheral edge having a flange extending outwardly therefrom and suitable for attachment to the side of said ring facing said pressurizable portion of said tunnel to retain the assembled bulkhead in said tunnel, said pressure resisting wall portion being convexly shaped for forming, upon assembly, a domed bulkhead capable of resisting the pressure generated in the pressurizable portion of the tunnel, said parting edges of said segments having plates mounted thereon extending axially within the dome of said bulkhead, said plates being abuttable along said parting line upon assembly of said bulkhead and containing means for joining said plates together to form said bulkhead, said segments being individually insertable into the pressurizable portion of said tunnel through the opening formed by said ring for assembly and erection within said tubular liner with the dome of said partition extending through said ring into the unpressurized portion of the tunnel.
2. The circular bulkhead of claim 1 wherein the parting line of said circular bulkhead and said straight parting edges of said segments are nondiametrical chords and said axially extending plates terminate at the plane of said peripheral flange.
3. The circular bulkhead of claim 1 including a plurality of means for retaining said flange of said bulkhead in contact with said ring during the assembly and erection of said bulkhead, each of said means comprising a bracket having a threaded bore, said bracket being mounted on the domed portion of said segments for locating said bracket within the unpressurized portion of said tunnel when said bulkhead is assembled and for positioning said threaded bore opposite said ring and on the opposite side thereof from said flange; and a threaded member mounted in said bore and movable into abutment with said ring for bringing said flange into contact with said ring.
4. The circular bulkhead of claim 2 wherein the said segments have a plurality of access openings therein.
1. A circular bulkhead formed of a pair of segments and capable of assembly and erection within the confines of a tunnel, said tunnel having a tubular liner of circular cross section and a ring secured to the interior of said liner at a predetermined location therealong, said ring having sides extending inwardly from said tunnel liner and defining pressurizable and unpressurized portions of the tunnel, said circular bulkhead being parted along a line forming a chord thereof to define said pair of segments, each of said bulkhead segments including a generally semicircular, pressure resisting wall portion having a peripheral edge and a straight parting edge lying on said chord, said peripheral edge having a flange extending outwardly therefrom and suitable for attachment to the side of said ring facing said pressurizable portion of said tunnel to retain the assembled bulkhead in said tunnel, said pressure resisting wall portion being convexly shaped for forming, upon assembly, a domed bulkhead capable of resisting the pressure generated in the pressurizable portion of the tunnel, said parting edges of said segments having plates mounted thereon extending axially within the dome of said bulkhead, said plates being abuttable along said parting line upon assembly of said bulkhead and containing means for joining said plates together to form said bulkhead, said segments being individually insertable into the pressurizable portion of said tunnel through the opening formed by said ring for assembly and erection within said tubular liner with the dome of said partition extending through said ring into the unpressurized portion of the tunnel.
2. The circular bulkhead of claim 1 wherein the parting line of said circular bulkhead and said straight parting edges of said segments are nondiametrical chords and said axially extending plates terminate at the plane of said peripheral flange.
3. The circular bulkhead of claim 1 including a plurality of means for retaining said flange of said bulkhead in contact with said ring during the assembly and erection of said bulkhead, each of said means comprising a bracket having a threaded bore, said bracket being mounted on the domed portion of said segments for locating said bracket within the unpressurized portion of said tunnel when said bulkhead is assembled and for positioning said threaded bore opposite said ring and on the opposite side thereof from said flange; and a threaded member mounted in said bore and movable into abutment with said ring for bringing said flange into contact with said ring.
4. The circular bulkhead of claim 2 wherein the said segments have a plurality of access openings therein.
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to earth engineering equipment of the type used in the construction of tunnels and caissons.
2. Description of the Prior Art
Underground passageways, such as subways or large sewers, are generally formed by an auger or other digging means which removes the earth from a forward working face in the passageway and carries it rearwardly for disposal. The sides of the passageway are lined with metal or concrete walls to form the completed tunnel or caisson structure.
It is often necessary to pressurize such tunnels or caissons during construction to keep out subterranean water and assist in maintaining the structural integrity of the tunnel or caisson walls. To effect such pressurization, transverse partitions or bulkheads are erected at desired locations along the tunnel so as to form sealed compartments in the tunnel which may be pressurized.
While the usual working range of tunnel compartment pressurization is between 15 and 35 lbs. per square inch, tunneling equipment must be able to meet emergencies wherein pressurization is as high as 50 lbs. per square inch. At such pressures, tremendous forces are placed on the transverse bulkheads, and forces in the range of 2 million lbs. are quite common. The primary tunnel lining is subjected to similar forces but such lining is backed by the surrounding earth which provides additional support. However, blowouts do nevertheless occur on occasion, resulting in probably the greatest possible type of tunnel construction disaster. Locks are therefore provided in an effort to prevent such disasters while also affording reentry for rescue and reconstruction.
For the foregoing reasons, the design, construction, and erection of the bulkheads in the tunnel or caisson is quite critical.
In the past, steel bulkheads have been fabricated outside the tunnel, lowered into the tunnel, and then fastened to the tunnel wall at a number of discrete load points about the periphery of the bulkhead. Concrete bulkheads have also been used in some instances, but they are very expensive to install as well as to remove.
While such techniques have worked reasonably well, they have required lifting, lowering, and installing large, heavy, fully assembled bulkheads. This is both awkward and dangerous. Further, if one of the discrete load points affixing the bulkhead to the tunnel wall fails, the force on the bulkhead is concentrated on the remaining load points causing subsequent and sequential failure of these load points and collapse of the bulkhead.
A means of gaining access to the pressurized compartments formed by the bulkheads must also be provided. In the past, only a single opening has generally been provided in the bulkhead through which both the men working in the tunnel compartment and the necessary materials and equipment must pass. The same single opening is used to remove the earth and muck from subsequent tunneling operations, as by a bucket lift or small vehicle.
Men working in the pressurized compartments of the tunnel or caisson are required to undergo decompression after emerging from the tunnel to prevent a condition of nitrogen embolism, commonly called caisson disease. Often the decompression comprises two successive exposures to decreasing pressures.
Such decompression is normally carried out in a decompression chamber coupled to the opening in the bulkhead. However, the constant movement of material and equipment in and out of the tunnel through the decompression chamber has required a system of air locks to prevent continual loss of pressure in the decompression chamber.
SUMMARY OF THE PRESENT INVENTION
It is, therefore, the object of the present invention to provide an improved means for gaining access to a pressurized work compartment, or vessel, as in a tunnel or caisson.
It is another object of the present invention to provide such an improved access means having a separate passageway for the movement of men and a separate passageway for the movement of materials and of equipment to and from the work compartment so as to permit men to enter and leave the work area through a decompression chamber undisturbed by the flow of material and equipment in and out of the compartment.
It is a further object of the present invention to provide an improved partition or bulkhead with which the foregoing access means may be used, said bulkhead being insertable in the work vessel in pieces and assembled therein, thereby avoiding the lifting and erection of a fully assembled bulkhead and the fabrication of the bulkhead outside the tunnel as required in the past.
It is an additional object of the present invention to provide an improved means for sealing the bulkhead to the tunnel wall so that the forces exerted on the bulkhead are evenly distributed about the periphery of the bulkhead rather than being concentrated at a number of discrete load points.
It is still a further object of the present invention to provide an improved jacking system for holding the dead weight of the bulkhead against the retainer or reaction ring until proper pressure conditions are established, thereby aiding in rapid erection.
A circular bulkhead is formed of a pair of segments and is capable of assembly and erection within the confines of a tunnel. The circular bulkhead is parted along a line forming a chord thereof to define the pair of segments. Each of the segments has a semicircular dome-shaped wall portion, a peripheral flange, and a plate on the parting edge extending axially within the dome of the bulkhead. The plates of the pair of segments are abuttable along the parting line upon assembly of the bulkhead and contain means for joining them together to form the bulkhead. The segments are individually insertable into the tunnel for assembly and erection therewithin and the assembled bulkhead is affixed, by means of the peripheral flange, to a ring provided on the tunnel liner.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective part-sectional view of one embodiment of the bulkhead of the present invention and of a portion of a tunnel with which it may be used;
FIG. 2 is a perspective part-sectional view of another embodiment of the bulkhead of the present invention and of a portion of a caisson with which it may be used;
FIG. 3 is an elevational view of the transverse partition or bulkhead of the present invention, a portion of the view being broken away to reveal a means for joining segments of the partition together;
FIG. 4 is a perspective view of one of the segments forming the partition, the view being taken generally along the line 4-4 of FIG. 3;
FIG. 5 is a fragmentary cross-sectional view, taken along line 5-5 of FIG. 1, showing the attachment of the bulkhead to the tunnel or caisson;
FIG. 6 is a fragmentary cross-sectional view taken along line 6-6 of FIG. 2 and showing an improved passageway framing means employed in an access means which may be employed with the bulkhead of the present invention; and
FIG. 7 is a fragmentary cross-sectional view, taken along lines 7-7 of FIGS. 1 and 2, and showing an observation means for viewing the interior of the decompression chamber of the access means.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The bulkhead of the present invention is designed for use in a tunnel or caisson 10 having a casing or wall comprised of a plurality of aligned portions 12 extending along the underground passageway formed by the tunnel. FIG. 1 shows a horizontal passageway while FIG. 2 shows a vertical passageway. The casing of tunnel 10 may be of tubular or other desired cross-sectional configuration, the former being exemplarily shown in the drawings. A ring 14 is inserted between two adjacent tunnel portions and secured thereto. Ring 14 extends inwardly towards the axis of tunnel 10 so that the inner periphery of ring 14, and the opening formed thereby, is smaller than the peripheral dimension of tunnel wall portions 12, thus forming an inwardly projecting annular flange.
As shown in FIGS. 1 and 2, a partition or bulkhead 16 is positioned across the open end of tunnel wall portions 12 so as to form a compartment or work area that may be pressurized for the purposes noted above. The other end of tunnel wall portions 12 may be sealed by the earthen face undergoing excavation or by another bulkhead.
In accordance with the present invention, bulkhead 16 is formed of a plurality of segments which are insertable through the opening formed by ring 14 for assembly and erection within the tunnel wall portions 12. While the assembled bulkhead 16 is shown herein as being generally circular in shape with a domed or convex portion 18 for effectively resisting the forces applied to the bulkhead by the pressurization of the work area, it may be in the form of a reinforced flat or plane closure, and as shown, the bulkhead is provided with at least two access openings.
The domed portion 18 is circumscribed by a peripheral flange 20. Dome 18 and flange 20 may be integrally formed or separately fabricated and then fastened together, as desired. Bulkhead 16 is dimensioned such that the circumference of flange 20 is less than the interior dimension of tunnel wall portion 12, but greater than the peripheral dimension of the inner flange formed by ring 14, so that upon erection of bulkhead 16, flange 20 may be placed in abutment with ring 14 and fastened thereto, as by jack screws or bolts 22 with a gasket 23 preferably inserted between flange 20 and ring 14.
As ring 14 is contiguous with flange 20 around the entire peripheries of both the ring and flange 20, the forces on bulkhead 16 are likewise evenly and continuously distributed around the ring and flange. This eliminates the support failure experienced heretofore when the bulkhead was fastened to the tunnel wall at a number of discrete load points.
Bulkhead 16 is formed of two generally semicircular segments, one of which is shown in detail in FIG. 4. It is understood that a greater number of smaller segments may be used if desired. Upper segment 24 and lower segment 26 are joined at a seam or splice preferably located slightly above the horizontal centerline of bulkhead 16 so that the abutting edges of upper segment 24 and lower segment 26 actually form chords of the bulkhead.
Each of the segments 24 and 26 of bulkhead 16 includes a semicircular portion of dome 18 and flange 20. The exposed edge of each of the segments is fastened to a plate 28 which lies in a plane normal to the surface of the dome and which extends into the dome. The unfastened, or lower, edge of plate 28 may lie flush with the lower surface of flange 20. A plurality of bolt holes 29 are included in plates 28, preferably adjacent the edges thereof.
One or more openings may be included in each of the segments forming bulkhead 16. FIG. 3 shows a bulkhead 16 suitable for use in the access means shown in FIG. 1. A pair of openings, or manholes, 32 and 34 are provided in upper segment 24. These openings are sized to allow the passage of men through the bulkhead. A larger, single opening 36 is provided in lower segment 26 which is sized to permit passage of equipment such as a mud bucket or small vehicle. Each of the openings may be surrounded by a collar attached to dome 18 and presenting a planar surface suitable for the attachment of additional portions of the access means. Collars 38 and 40 surround manholes 32 and 34 respectively, and collar 42 surrounds ring 36.
Semicircular segments 26 and 28 of the bulkhead are individually inserted through the opening formed by the ring 14 and placed in the tunnel wall portion 12 forming part of the pressurized work area or compartment. The segments are then arranged so that the plates 28 of each of the segments are in abutment with bolt holes 29 in alignment. Bolts 31 are inserted through the holes 29 in both of the segments and nuts 33 tightened to form the bulkhead segments into an integral bulkhead structure. The bulkhead 16 is then erected so that upper segment 24 is above lower segment 26 and flange 20 is in abutment with ring 14. Bulkhead 16 is fastened to ring 14 by the bolts 22 which force flange 20 against ring 14.
Decompression chambers are attached to the collars 38 and 40 surrounding manholes 32 and 34 so that workmen leaving the pressurized work area through the manholes in bulkhead 16 may undergo decompression in the chambers (See FIG. 1). Decompression chamber 44, attached to a collar 38 or the like, is utilized under normal conditions. For this purpose, decompression chamber 44 includes two decompression stages or tanks, 441 and 442, which are pressurized at successively lower pressures. Decompression tanks 441 and 442 are separated by a transition tank 443 having an entrance and exit door 46. Decompression chamber 48 attached to collar 40 may be a single stage decompression chamber for emergency use. The decompression chambers may be pressurized from the same compressed air source used to pressurize tunnel 10 or by a separate source, as desired.
Tank 441 of decompression chamber 44 is formed by a continuous chamber wall 50 closed at either end by end walls. End wall 52 is adapted to mate with collar 38 so that a hatch 53 therein is aligned with manhole 32, thus permitting access to tank 441 from the manhole. End wall 54 is affixed to an end wall 55 of transition tank 443. These end walls are joined so that wall hatches therein are mutually accessible.
Tank 442 is formed in a manner similar to that of tank 441 to include a continuous chamber wall 56 closed by end walls 58 and 60 at either end. End wall 60 is a solid wall while end wall 56 contains a hatch which is accessible from transition tank 443 when the end walls of the two tanks are joined.
Decompression chamber 48 may be comprised of a single tank, one end of which is mated to collar 40, and the other end of which contains an exit hatch.
As shown in FIG. 7, one or both of the abutting end walls 54 and 55 of tanks 441 and 443 may contain a sight glass 62 and 64, respectively, for permitting observation within the tanks. To eliminate the necessity of the observer having to enter the transition tank 443 in order to observe the interior of tank 441, thus needlessly subjecting himself to the pressure in the transition tank or reducing the pressure in the tank by opening door 46, an image transmitting means may be coupled to the sight glass 64 to extend through the chamber wall 66 of transition tank 443. This permits an observer outside the transition tank 443 to observe the interior of tank 441. Such an image transmitting means may comprise a curved, or right angular viewing tube 68 having one end affixed to sight glass 64 and the other end extending through wall 66. A mirror 70, or like reflecting means, is positioned in the tube to transmit the image appearing in the sight glass 64 around the bend in the tube, thus forming a connection from tank 441 extending through a portion of tank 443 and being subjected to external pressure from time to time.
FIG. 2 shows a bulkhead 16 having a single manhole 32. A vertical pipe 72 terminating in an elbow member 74 is used to couple the manhole to transition tank 443 of decompression chamber 444. Decompression chamber 444 includes a single decompression stage or tank similar to tank 442.
Opening 36 in bulkhead 16, which is used to supply materials and equipment to the pressurized work area and to remove mud and the like is sealed by a removable hatch or door 76, which may be placed directly on collar 42 and affixed thereto. However, it is generally more convenient to position a tubular member 48 in alignment with opening 36 with one end of the member attached to collar 42 and the other end presenting an opening across which door 76 is placed.
Door 76 includes the appropriate supporting members 77 and braces to enable it to resist the force applied to it by the air pressure in tunnel 10. FIG. 2 shows a door 761 which is split in half so that the halves may be retracted into housing 80, mounted on the top of cylindrical member 78, thereby permitting access to member 78 and opening 36. In any event, it is important to arrange the sealing surfaces in a manner whereby the door will positively remain closed against the air pressure in the lock.
In order to provide a tubular member 78 of a variable length, the member is formed from a plurality of tubes 781, bolted together to form the completed member 78. The assembly of member 78 is facilitated by the use of box section flanges 82 at either end of tubes 781 (see FIG. 6). The flanges may be economically formed by rolling channel iron into a ring of the desired dimension with the channel opening toward the outer periphery of the ring. The terminal, or outer portions of the sides of the ring may be welded to the interior of tubes 781. Bolt holes are drilled through the sides of the box section flange so formed.
The tubular member 78 is preferably constructed by placing two or more tubes 781 in axial alignment, the tubes having channel sections 82 welded thereto in flange abutting relation as shown in FIG. 6. Bolts 84 are then extended through the flanges of the channel or box sections of the adjacent tubes 781 and nuts 86 are placed thereon and tightened to draw the adjacent tube ends and box flanges into abutment to form the completed structure. The box section flanges 82 thus not only serve to distribute the forces generated during the assembly, but the bending stresses placed on the relatively long bolts are also minimized by the channel sections and the flanges thereof. This gives the bolts important fatigue resistance, the importance of which is emphasized by the fact that the locks are constantly pressurized and depressurized as the doors are opened and closed, thus creating an alternating load on the connecting parts. Of course, it should also be understood that appropriate seals and/or gaskets may be used as found necessary and desirable.
Various modes of carrying out the invention are contemplated as being within the scope of the following claims, particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.
1. Field of the Invention
The present invention relates to earth engineering equipment of the type used in the construction of tunnels and caissons.
2. Description of the Prior Art
Underground passageways, such as subways or large sewers, are generally formed by an auger or other digging means which removes the earth from a forward working face in the passageway and carries it rearwardly for disposal. The sides of the passageway are lined with metal or concrete walls to form the completed tunnel or caisson structure.
It is often necessary to pressurize such tunnels or caissons during construction to keep out subterranean water and assist in maintaining the structural integrity of the tunnel or caisson walls. To effect such pressurization, transverse partitions or bulkheads are erected at desired locations along the tunnel so as to form sealed compartments in the tunnel which may be pressurized.
While the usual working range of tunnel compartment pressurization is between 15 and 35 lbs. per square inch, tunneling equipment must be able to meet emergencies wherein pressurization is as high as 50 lbs. per square inch. At such pressures, tremendous forces are placed on the transverse bulkheads, and forces in the range of 2 million lbs. are quite common. The primary tunnel lining is subjected to similar forces but such lining is backed by the surrounding earth which provides additional support. However, blowouts do nevertheless occur on occasion, resulting in probably the greatest possible type of tunnel construction disaster. Locks are therefore provided in an effort to prevent such disasters while also affording reentry for rescue and reconstruction.
For the foregoing reasons, the design, construction, and erection of the bulkheads in the tunnel or caisson is quite critical.
In the past, steel bulkheads have been fabricated outside the tunnel, lowered into the tunnel, and then fastened to the tunnel wall at a number of discrete load points about the periphery of the bulkhead. Concrete bulkheads have also been used in some instances, but they are very expensive to install as well as to remove.
While such techniques have worked reasonably well, they have required lifting, lowering, and installing large, heavy, fully assembled bulkheads. This is both awkward and dangerous. Further, if one of the discrete load points affixing the bulkhead to the tunnel wall fails, the force on the bulkhead is concentrated on the remaining load points causing subsequent and sequential failure of these load points and collapse of the bulkhead.
A means of gaining access to the pressurized compartments formed by the bulkheads must also be provided. In the past, only a single opening has generally been provided in the bulkhead through which both the men working in the tunnel compartment and the necessary materials and equipment must pass. The same single opening is used to remove the earth and muck from subsequent tunneling operations, as by a bucket lift or small vehicle.
Men working in the pressurized compartments of the tunnel or caisson are required to undergo decompression after emerging from the tunnel to prevent a condition of nitrogen embolism, commonly called caisson disease. Often the decompression comprises two successive exposures to decreasing pressures.
Such decompression is normally carried out in a decompression chamber coupled to the opening in the bulkhead. However, the constant movement of material and equipment in and out of the tunnel through the decompression chamber has required a system of air locks to prevent continual loss of pressure in the decompression chamber.
SUMMARY OF THE PRESENT INVENTION
It is, therefore, the object of the present invention to provide an improved means for gaining access to a pressurized work compartment, or vessel, as in a tunnel or caisson.
It is another object of the present invention to provide such an improved access means having a separate passageway for the movement of men and a separate passageway for the movement of materials and of equipment to and from the work compartment so as to permit men to enter and leave the work area through a decompression chamber undisturbed by the flow of material and equipment in and out of the compartment.
It is a further object of the present invention to provide an improved partition or bulkhead with which the foregoing access means may be used, said bulkhead being insertable in the work vessel in pieces and assembled therein, thereby avoiding the lifting and erection of a fully assembled bulkhead and the fabrication of the bulkhead outside the tunnel as required in the past.
It is an additional object of the present invention to provide an improved means for sealing the bulkhead to the tunnel wall so that the forces exerted on the bulkhead are evenly distributed about the periphery of the bulkhead rather than being concentrated at a number of discrete load points.
It is still a further object of the present invention to provide an improved jacking system for holding the dead weight of the bulkhead against the retainer or reaction ring until proper pressure conditions are established, thereby aiding in rapid erection.
A circular bulkhead is formed of a pair of segments and is capable of assembly and erection within the confines of a tunnel. The circular bulkhead is parted along a line forming a chord thereof to define the pair of segments. Each of the segments has a semicircular dome-shaped wall portion, a peripheral flange, and a plate on the parting edge extending axially within the dome of the bulkhead. The plates of the pair of segments are abuttable along the parting line upon assembly of the bulkhead and contain means for joining them together to form the bulkhead. The segments are individually insertable into the tunnel for assembly and erection therewithin and the assembled bulkhead is affixed, by means of the peripheral flange, to a ring provided on the tunnel liner.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective part-sectional view of one embodiment of the bulkhead of the present invention and of a portion of a tunnel with which it may be used;
FIG. 2 is a perspective part-sectional view of another embodiment of the bulkhead of the present invention and of a portion of a caisson with which it may be used;
FIG. 3 is an elevational view of the transverse partition or bulkhead of the present invention, a portion of the view being broken away to reveal a means for joining segments of the partition together;
FIG. 4 is a perspective view of one of the segments forming the partition, the view being taken generally along the line 4-4 of FIG. 3;
FIG. 5 is a fragmentary cross-sectional view, taken along line 5-5 of FIG. 1, showing the attachment of the bulkhead to the tunnel or caisson;
FIG. 6 is a fragmentary cross-sectional view taken along line 6-6 of FIG. 2 and showing an improved passageway framing means employed in an access means which may be employed with the bulkhead of the present invention; and
FIG. 7 is a fragmentary cross-sectional view, taken along lines 7-7 of FIGS. 1 and 2, and showing an observation means for viewing the interior of the decompression chamber of the access means.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The bulkhead of the present invention is designed for use in a tunnel or caisson 10 having a casing or wall comprised of a plurality of aligned portions 12 extending along the underground passageway formed by the tunnel. FIG. 1 shows a horizontal passageway while FIG. 2 shows a vertical passageway. The casing of tunnel 10 may be of tubular or other desired cross-sectional configuration, the former being exemplarily shown in the drawings. A ring 14 is inserted between two adjacent tunnel portions and secured thereto. Ring 14 extends inwardly towards the axis of tunnel 10 so that the inner periphery of ring 14, and the opening formed thereby, is smaller than the peripheral dimension of tunnel wall portions 12, thus forming an inwardly projecting annular flange.
As shown in FIGS. 1 and 2, a partition or bulkhead 16 is positioned across the open end of tunnel wall portions 12 so as to form a compartment or work area that may be pressurized for the purposes noted above. The other end of tunnel wall portions 12 may be sealed by the earthen face undergoing excavation or by another bulkhead.
In accordance with the present invention, bulkhead 16 is formed of a plurality of segments which are insertable through the opening formed by ring 14 for assembly and erection within the tunnel wall portions 12. While the assembled bulkhead 16 is shown herein as being generally circular in shape with a domed or convex portion 18 for effectively resisting the forces applied to the bulkhead by the pressurization of the work area, it may be in the form of a reinforced flat or plane closure, and as shown, the bulkhead is provided with at least two access openings.
The domed portion 18 is circumscribed by a peripheral flange 20. Dome 18 and flange 20 may be integrally formed or separately fabricated and then fastened together, as desired. Bulkhead 16 is dimensioned such that the circumference of flange 20 is less than the interior dimension of tunnel wall portion 12, but greater than the peripheral dimension of the inner flange formed by ring 14, so that upon erection of bulkhead 16, flange 20 may be placed in abutment with ring 14 and fastened thereto, as by jack screws or bolts 22 with a gasket 23 preferably inserted between flange 20 and ring 14.
As ring 14 is contiguous with flange 20 around the entire peripheries of both the ring and flange 20, the forces on bulkhead 16 are likewise evenly and continuously distributed around the ring and flange. This eliminates the support failure experienced heretofore when the bulkhead was fastened to the tunnel wall at a number of discrete load points.
Bulkhead 16 is formed of two generally semicircular segments, one of which is shown in detail in FIG. 4. It is understood that a greater number of smaller segments may be used if desired. Upper segment 24 and lower segment 26 are joined at a seam or splice preferably located slightly above the horizontal centerline of bulkhead 16 so that the abutting edges of upper segment 24 and lower segment 26 actually form chords of the bulkhead.
Each of the segments 24 and 26 of bulkhead 16 includes a semicircular portion of dome 18 and flange 20. The exposed edge of each of the segments is fastened to a plate 28 which lies in a plane normal to the surface of the dome and which extends into the dome. The unfastened, or lower, edge of plate 28 may lie flush with the lower surface of flange 20. A plurality of bolt holes 29 are included in plates 28, preferably adjacent the edges thereof.
One or more openings may be included in each of the segments forming bulkhead 16. FIG. 3 shows a bulkhead 16 suitable for use in the access means shown in FIG. 1. A pair of openings, or manholes, 32 and 34 are provided in upper segment 24. These openings are sized to allow the passage of men through the bulkhead. A larger, single opening 36 is provided in lower segment 26 which is sized to permit passage of equipment such as a mud bucket or small vehicle. Each of the openings may be surrounded by a collar attached to dome 18 and presenting a planar surface suitable for the attachment of additional portions of the access means. Collars 38 and 40 surround manholes 32 and 34 respectively, and collar 42 surrounds ring 36.
Semicircular segments 26 and 28 of the bulkhead are individually inserted through the opening formed by the ring 14 and placed in the tunnel wall portion 12 forming part of the pressurized work area or compartment. The segments are then arranged so that the plates 28 of each of the segments are in abutment with bolt holes 29 in alignment. Bolts 31 are inserted through the holes 29 in both of the segments and nuts 33 tightened to form the bulkhead segments into an integral bulkhead structure. The bulkhead 16 is then erected so that upper segment 24 is above lower segment 26 and flange 20 is in abutment with ring 14. Bulkhead 16 is fastened to ring 14 by the bolts 22 which force flange 20 against ring 14.
Decompression chambers are attached to the collars 38 and 40 surrounding manholes 32 and 34 so that workmen leaving the pressurized work area through the manholes in bulkhead 16 may undergo decompression in the chambers (See FIG. 1). Decompression chamber 44, attached to a collar 38 or the like, is utilized under normal conditions. For this purpose, decompression chamber 44 includes two decompression stages or tanks, 441 and 442, which are pressurized at successively lower pressures. Decompression tanks 441 and 442 are separated by a transition tank 443 having an entrance and exit door 46. Decompression chamber 48 attached to collar 40 may be a single stage decompression chamber for emergency use. The decompression chambers may be pressurized from the same compressed air source used to pressurize tunnel 10 or by a separate source, as desired.
Tank 441 of decompression chamber 44 is formed by a continuous chamber wall 50 closed at either end by end walls. End wall 52 is adapted to mate with collar 38 so that a hatch 53 therein is aligned with manhole 32, thus permitting access to tank 441 from the manhole. End wall 54 is affixed to an end wall 55 of transition tank 443. These end walls are joined so that wall hatches therein are mutually accessible.
Tank 442 is formed in a manner similar to that of tank 441 to include a continuous chamber wall 56 closed by end walls 58 and 60 at either end. End wall 60 is a solid wall while end wall 56 contains a hatch which is accessible from transition tank 443 when the end walls of the two tanks are joined.
Decompression chamber 48 may be comprised of a single tank, one end of which is mated to collar 40, and the other end of which contains an exit hatch.
As shown in FIG. 7, one or both of the abutting end walls 54 and 55 of tanks 441 and 443 may contain a sight glass 62 and 64, respectively, for permitting observation within the tanks. To eliminate the necessity of the observer having to enter the transition tank 443 in order to observe the interior of tank 441, thus needlessly subjecting himself to the pressure in the transition tank or reducing the pressure in the tank by opening door 46, an image transmitting means may be coupled to the sight glass 64 to extend through the chamber wall 66 of transition tank 443. This permits an observer outside the transition tank 443 to observe the interior of tank 441. Such an image transmitting means may comprise a curved, or right angular viewing tube 68 having one end affixed to sight glass 64 and the other end extending through wall 66. A mirror 70, or like reflecting means, is positioned in the tube to transmit the image appearing in the sight glass 64 around the bend in the tube, thus forming a connection from tank 441 extending through a portion of tank 443 and being subjected to external pressure from time to time.
FIG. 2 shows a bulkhead 16 having a single manhole 32. A vertical pipe 72 terminating in an elbow member 74 is used to couple the manhole to transition tank 443 of decompression chamber 444. Decompression chamber 444 includes a single decompression stage or tank similar to tank 442.
Opening 36 in bulkhead 16, which is used to supply materials and equipment to the pressurized work area and to remove mud and the like is sealed by a removable hatch or door 76, which may be placed directly on collar 42 and affixed thereto. However, it is generally more convenient to position a tubular member 48 in alignment with opening 36 with one end of the member attached to collar 42 and the other end presenting an opening across which door 76 is placed.
Door 76 includes the appropriate supporting members 77 and braces to enable it to resist the force applied to it by the air pressure in tunnel 10. FIG. 2 shows a door 761 which is split in half so that the halves may be retracted into housing 80, mounted on the top of cylindrical member 78, thereby permitting access to member 78 and opening 36. In any event, it is important to arrange the sealing surfaces in a manner whereby the door will positively remain closed against the air pressure in the lock.
In order to provide a tubular member 78 of a variable length, the member is formed from a plurality of tubes 781, bolted together to form the completed member 78. The assembly of member 78 is facilitated by the use of box section flanges 82 at either end of tubes 781 (see FIG. 6). The flanges may be economically formed by rolling channel iron into a ring of the desired dimension with the channel opening toward the outer periphery of the ring. The terminal, or outer portions of the sides of the ring may be welded to the interior of tubes 781. Bolt holes are drilled through the sides of the box section flange so formed.
The tubular member 78 is preferably constructed by placing two or more tubes 781 in axial alignment, the tubes having channel sections 82 welded thereto in flange abutting relation as shown in FIG. 6. Bolts 84 are then extended through the flanges of the channel or box sections of the adjacent tubes 781 and nuts 86 are placed thereon and tightened to draw the adjacent tube ends and box flanges into abutment to form the completed structure. The box section flanges 82 thus not only serve to distribute the forces generated during the assembly, but the bending stresses placed on the relatively long bolts are also minimized by the channel sections and the flanges thereof. This gives the bolts important fatigue resistance, the importance of which is emphasized by the fact that the locks are constantly pressurized and depressurized as the doors are opened and closed, thus creating an alternating load on the connecting parts. Of course, it should also be understood that appropriate seals and/or gaskets may be used as found necessary and desirable.
Various modes of carrying out the invention are contemplated as being within the scope of the following claims, particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.