US3410098A

US3410098A - Tail section seals for shield tunneling machines

Info

Publication number: US3410098A
Application number: US415132A
Authority: US
Inventors: Douglas F Winberg
Original assignee: Robbins & Assoc James S
Current assignee: JAMES S ROBBINS AND ASSOCIATES Inc; Robbins & Assoc James S
Priority date: 1964-12-01
Filing date: 1964-12-01
Publication date: 1968-11-12
Anticipated expiration: 1985-11-12
Also published as: DE1784928C3; DE1784928B2; GB1128766A; GB1128765A; DE1784928A1; DE1534659B1

Description

Nov. 12, 1968 F. WINBERG 5 Sheets-Sheet 1 Filed Dec.

Nov. 12, 1968 D. F. WINBERG TAIL SECTION SEALS FOR SHIELD TUNNELING MACHINES 5 Sheets-Sheet 2 Filed Dec. 1, 1964 .INVENT'O/P 901/624! F Mil 85% 11 3 agg/gwd 4 Trek V6315 No o n Nov. 12, 1968 D. F. WINBERG 3,410,098

TAIL SECTION SEALS FOR SHIELD TUNNELING MACHINES Filed Dec. 1, 1964 5 Sheets-Sheet A TORNEYS Nov. 12, 1968 D. F. WINBERG TAIL SECTION SEALS FOR SHIELD TUNNELING MACHINES 5 Sheets-Sheet 4 Filed Dec. 1, 1964 INVENTOR 00060481: MA/5/?6 ,6 fmwf ATTORNEYS Nov. 12, 1968 D. F. WINBERG 3,410,098

TAIL SECTION SEALS FOR SHIELD TUNNELING MACHINES Filed Dec. 1, 1964 5 Sheets-Sheet 5 og "6 I00 IN V EN TOR 006/6246 F MIA/8676 ATTORNEYS 3,410,098 TAIL SECTION SEALS FOR SHIELD TUNNELING MACHINES Douglas F. Winberg, Hibbing, Minn., assignor to James S. Robbins and Associates, Inc., Seattle, Wash., a corporation of Washington Filed Dec. 1, 1964, Ser. No. 415,132 17 Claims. (CI. 6185) ABSTRACT OF THE DISCLOSURE A tunneling shield seal located between the tail section of the shield and a radially inwardly positioned portion of the tunnel lining. A segmented spring steel ring secured at its forward end to the tail section and curving inwardly therefrom and making contact with the tunnel lining. The free portion of such spring is slotted axially of the tunnel to form a plurality of circumferentially spaced apart fingers, the resiliency of which maintains them in contact with the tunnel lining. An air bladder or solid foam body fills the space between such ring and the tail section. A plurality of forwardly directed tongues separated 'by cutout areas. Mounting means comprising sockets for receiving the tongues, formed by a circumferential ring bridging across circumferentially spaced apart riser blocks, and wedges insertable between the tongues and the inner surface of the shield, and lockable in place by set screws or the like.

Cross references to related applications This application contains some subject matter which is disclosed in copending application Ser. No. 284,604, entitled, Shield Tunneling Method and Mechanism, filed May 31, 1963, by myself and four others. Thus, this is a sole continuation-in-part application of the prior joint application involving me as one of the inventors but directed to different inventive subject matter.

The present invention relates to shield tunneling machines, and more particularly to tail section seals for such machines.

Quite briefly, a typical shield tunneling machine comprises a generally cylindrical skin, a transverse wall structure dividing such skin into nose and tail sections, and a forwardly facing cutterhead rotatively mounted on the transverse wall structure.

In tunneling operations according to the technique described in the Larrouze et al United States Patent No. 3,266,257, now Patent 3,266,257, a lining is erected generally in the wake of the machine, but under cover of the shields tail section. The transverse wall structure is a pressure bulkhead, and compressed air is delivered to the face region of the tunnel, forwardly of such bulkhead. The pressurized zone at the face of the tunnel is hermetically sealed from the non-pressurized portion of the tunnel situated rearwardly of the bulkhead. The present invention relates to an effective seal for use between the tail section and the tunnel lining where the former envelops or surrounds the latter.

Generally speaking, tail section seal assemblies according to the present invention comprise a dirt seal and at least one, but preferably at least two, pressure seals. Both the dirt and pressure seals include a seal ring composed of a circular series of spring steel plates, each comprising a fixed or mounting edge portion that is firmly secured to the tail section of the shield, a relatively flexible free edge portion having a seal surface in sliding contact or engagement with the forward portion of the tunnel lining, and an intermediate portion interconnecting such fixed and free edge portions. The intermediate and free edge portions of the ring are slotted, and the slots open rearnited States Patent wardly and extend generally parallel to the center axis of the ring. The slots divide the intermediate and free edge portions of the ring into a plurality of fingers. It is this alternating slot and finger construction that makes the free edge portion of the seal ring relatively flexible. The free edge portion of the seal ring is offset radially inwardly from the mounting portion of said ring relative to the tail section of the shield. As a result, the circumference of the ring is smaller in said free edge portion than it is in said mounting edge portion. Due to this difference in circumference, the rearward portions of the fingers are spaced closer together than the forward portions of the fingers, and the slots between fingers are narrower in their rear portions than they are in their forward portions. The tunnel lining is not perfectly round, it varies in diameter and circumference from one portion of its length to the next. Consequently, as the shield is moving forwardly, with the seal surfaces of the fingers in sliding contact with the tunnel lining (at the free edge of the metallic rings), the fingers move either radially inwardly or outwardly under the influence of changes in the surface characteristics of the tunnel lining, and at the same time the spacing of the fingers varies.

According to the present invention, the pressure seals also include a resilient cushioning body situated between the metallic seal ring and the tail section of the shield. Preferably, this body possesses a generally triangular or wedge-like cross-sectional configuration, with its apex being located substantially where the intermediate and mounting portion of the metallic ring meet, To exclude dirt or muck from interfering with movement of the metallic ring, the cushioning body preferably substantially completely fills the space between the intermediate portion of the metallic ring and the adjacent portion of the inner surface of the tail section. Preferably, the resilient body is bonded directly to the metallic ring. The cushioning body also serves to resiliently urge the fingers of the ring toward the tunnel lining to aid in maintaining the seal surface of the ring in contact with the outer surface of the tunnel lining. According-lto the invention, the seal ring and the cushioning body together form a substantially impervious barrier to fluids tending to flow between the tail section and the lining.

The metallic seal ring and the cushioning body are preferably both of sectional construction, and the cushioning body sections are bonded to the seal ring sections to form a plurality of pressure seal segments. The dirt seal is preferably also of sectional construction.

According to the present invention, the individual segments of the pressure seal and the individual sections or segments of the dirt seal are individually mounted or secured to the tail section so that the seal rings as a whole can be easily installed and removed, and the separate segments or sections may be individually removed and replaced if they become damaged or suf'ficiently worn that replacement is necessary. The seal segments or sections are provided with forwardly projecting tongues, constituting parts of the mounting or fixed edge portions of such seals. These tongues are received in sockets formed on and extending around the inside surface of the tail section. The socket openings are relatively short and have two open ends. A wedge is inserted into the end of each socket that is opposite the end through which the tongue enters. The wedges are driven into a force fit between the tongues and the tail section, and they serve to secure the seal segments or sections in place. The pressure seal segments and dirt seal sections may also be formed to include forwardly opening blind slots between the tongues, and the tail section of the shield provided with posts in the paths of such slots arranged such that when the tongues are engaged in the sockets, the posts are engaged by the blind slots. The posts may take the form of a bolt or stud equipped with a head and a large washer. When the seal segments or sections are in place the bolts or studs are threaded in or tightened so the washers can exert a clamping effect on such segments or sections and serve as an additional means for securing the seal seg ments or sections to the tail section of the shield.

According to the present invention, one form of cushioning body comprises an air bladder associated with each section of the metallic ring. The air bladded is preferably bonded directly to its section of the metallic ring. Compressed air is delivered to each such bladder through tubing carried by the tunneling shield. A second form of cushioning body comprises a core of a suitable flexible foam plastic, such as open cell urethane plastic, for example, covered by layers of open cell neoprene foam. A waterproof casing or skin, such as neoprene sheet, for example, may be provided over the Widely exposed areas of the cushioning body.

A known prior art seal for the tail section of a tunneling shield is disclosed in United States Patent No. 794,633, issued July 11, 1905, to E. W. Moir. The tunneling technique of Moir involves pressurizing the interior of the tunnel, and the Moir seal functions to prevent the escape of air out from the interior of the tunnel. The Moir seal comprises two rings of bowed spring-plates, one ring overlapping the other. The joints between the plates of each ring are staggered with respect to the joints between the plates of the other ring. Both rings are essential to the establishment of an effective seal. The Moir seal also includes a rubber tube situated between the tail section and the overlapped ring of spring-plates. Compressed air is supplied to the tube for the purpose of flexing the plates against the tunnel lining.

These and other objects, features, advantages, and characteristics of the present invention will be apparent from the following description of typical and therefore nonlimitive embodiments thereof, wherein like letters and numerals refer to like parts, and wherein:

FIG. 1 is a small scale, side elevational view of the shield tunneling machine in operation, with the shield skin, the cutterhead, the cutterhead support, and the tunnel lining presented in longitudinal section;

FIG. 2 is a fragmentary, longitudinal sectional view of a typical seal arrangement usable between the tail section of the shield skin and the forward portion of the previously elected tunnel lining situated adjacent thereof;

FIG. 3 is a rear end elevational view of a fragmented portion of the tail section seal of FIG. 2 with the shield skin shown in section, and with the section being taken substantially along line 3-3 of FIG. 2;

FIG. 4 is a transverse sectional view of the shield, taken substantially along line 4-4 of FIG. 1, with the tunnel lining and the various components of the tunneling machine surrounded thereby being omitted for clarity of illustration, such view showing the sectional nature of the annular pressure seals and the dirt seal, characterizing the tail section seal means of the present invention;

FIG. 5 is a view similar to FIG. 2, but taken substantially along line 55 of FIGS. 4 and 6, such view presenting a modified form of resilient body for urging the sealing lip of the sealing ring against the outer surface of the tunnel lining;

FIG. 6 is a fragmentary plan view from an aspect inside the shield skin looking outwardly towards one of th seal units;

FIG. 7 is a fragmentary sectional view taken substantially along line 77 of FIG. 6;

FIG. 8 is an exploded perspective view of a fragmented portion of the seal ring and the retainer bar that is affixed thereto, as by rivets;

FIG. 9 is a fragmentary sectional view, with parts in section, taken at one of the flatheaded retaining studs that screw into a lower portion of the shield skin, such view showing a leading edge portion of the seal ring, in

the vicinity of one of the forwardly opening, retainer stud engaging slots, advancing toward the beveled periphery of one of the retaining washers and displacing the same upwardly;

FIG. 10 is a perspective view of one of the wedges used for locking a seal segment in place;

FIG. 11 is a transverse sectional view of the resilient cushioning body per se, showing a preferred construction of the same; and

FIG. 12 is a transverse sectional view of the dirt seal removed from the shield skin.

Referring now to the figures of the drawing in more detail, the tunneling machine shown in FIG. 1 includes a shield S characterized by a generally cylindrical skin 10 having a nose section equipped with a cutting edge 12, and a tail section 14, and a transverse cutterhead support CS spanning the interior of the skin 10 intermediate the ends thereof. A rotary cutterhead C is mounted for rotation on the front wall 16 of the cutterhead support CS, preferably by means of an annular bearing 18.

The front face of the cutterhead C is provided with a plurality of knives or cutters, some of which are designated 20. The cutters 20 are placed at different distances from the center of the cutterhead C, and when the cutterhead C revolves such cutters cut concentric grooves in the face of the tunnel, resulting in a breakaway of the face of the tunnel to the depth of the cut. The cutterhead C is revolved by means of a plurality of pinion gears 22, which mesh with a large bull gear 24 forming an integral part of the inner race 26 and the bull gear 24 are suitably attached to the cutterhead C, as by means of a series of nut and bolt assemblies, for example. The motive power is furnished by a plurality of motors M, to which the pinion gears 22 are drivingly connected.

A plurality of buckets B are circumferentially arranged about the periphery of the cutterhead C. Generally speaking, the buckets B open in a direction of rotation of the cutterhead C, to pick up the mined material from the ground and the tunnel face during rotation and advancing movement of the cutterhead C into the working face of thetunnel. The buckets B have radially inwardly extending discharge chute portions, one of which is shown at 26 in FIG. 1, discharging the mine-d material into a receiving conveyor 28 located within a central opening or passageway 30 extending through cutterhead support CS. A defiector 32 is used to guide the mined material onto the conveyor 28.

The conveyor 28 is preferably constructed of metal pads linked together so as to form a durable belt that is able to resist the shock of the mined material falling on it from the chutes 26. It feeds the mined material onto a longer conveyor 34 comprising an endless belt constructed ofrubber or a similar material. Conveyor 34 is contained partially within an erector tube 36 and partially within a conveyor tube 38 extending rearwardly out from said erector tube 36 to communicate at its rearmost end with a hopper dome 40.

An appropriate seal, suitably in the form of a flexible annular collar 42, interconnects between erector tube 36 and conveyor tube 38. Within the enclosure of the hopper dome 4Q, conveyor 34 deposits the mined material into one or the other of a pair of discharge hoppers H1, H2. Erector tube 36, conveyor tube 38, hopper dome 40, and hoppers H1, H2, together comprise what may be termed the material compartment, through which the mined material is transported from the face region of the tunnel to the tunnel conveyor TC. The tunnel conveyor TC carries the mined material to a discharge station, preferably located outside of the tunnel.

A forward extension 44 of conveyor tube 38 is universally mounted within the disclosure of erector tube 36 onto cutterhead support CS at the location designated 46 in FIG. 1. The rear end of the material compartment is supported by laterally spaced carriages 48, having flanged wheels riding along rails 50, which rails are in turn supported and extended when necessary in accordance with conventional practice.

The tunnel is lined as it is dug, and the lining, designated generally at L and characterized by series of axially abutting rings of circumferentially abutting segments, is continuously erected generally in the wake of the shield S, but under cover of the tail section 14 of the skin 10. Mechanical means termed erectors are used for handling the lining segments LS during erection of each new ring. The particular erector mechanism illustrated involves two erector units, designated E1, E2, respectively, in FIG. 1.

The shoving, driving, or moving forward of the shield S and the rotary cutterheads C carried thereby is accomplished by means of hydraulic jacks or rams R attached to the shield structure and reacting against the tunnel lining previously erected. The hydraulic rams R are circumferentially spaced around the periphery of the cutterhead support CS contiguous the inner surface of tail section 14. As described in detail in the aforementioned Larrouze et al. Patent No. 3,266,257, the lowermost pair of rams R are preferably set flush with the rear face of the cutterhead support S and the other rams R are offset from such face by progressively increasing amounts proceeding from said lower pair and extending upwardly on both sides thereof, with the topmost three rams R being offset the most and by equal amounts. This makes it possible to continuously move the machine forward without stoppage while erecting the tunnel lining L.

The means for transporting the tunnel lining segments LS from the surface work site to a location within the reach of the segment erectors E1, E2 may consist of an overhead rail and carriage assembly 52, as shown in FIG. 1, for example. In accordance with usual practice, additional sections of rail are added to said assembly 52 as is necessary to keep up with the forward progress of the tunneling machine.

Only the material compartment comprising erector tube 36, conveyor tube 38, hopper dome 40 and the hoppers H1, H2; the interior of the cutterhead support CS; the region between the cutterhead support CS and the tunnel face; and the annular zone immediately surrounding the shield S and the forward portion of the tunnel lining L are under pressure. The tunnel itself to the rear of cutterhead support CS and within the enclosure of the lining L is open throughout and communicates at its portal or entrance end with the atmosphere. Thus, except in those regions just mentioned, the various tunneling operations are conducted at atmospheric pressure.

The rear wall 54 of the assembly consisting of the cutterhead support CS and an annular ram pedestal RP, attached to and extending rearwardly of the cutterhead support CS, forms a bulkhead between the pressurized and unpressurized regions. Airtight seals interconnect between the motors M and the bulkhead 54 and also between the ram cylinders and bulkhead 54. The connection or erector tube 36 to cutterhead support CS is also airtight, and of course the large seal 42 interconnecting between erector tube 36 and conveyor tube 38 is a pressure seal, i.e. it too is airtight.

The hoppers H1, H2 each include an upper door and a lower door. Each of such doors are suitably constructed so as to be completely sealed when closed, and at least one door of each of the hoppers H1, H2 is closed during each stage of the tunneling operation.

An airtight seal is also maintained between the inner surface of tail section 14 and the outer surface of the tunnel lining L, in the region where tail section 14 concentrically surrounds the forward portion of the lining L. According to the present invention, the seal assembly SS for this region comprises one or more pressure seals PS, and preferably one dirt seal DS.

Each pressure seal PS is annular in form and comprises a series of individually mounted, circumferentially and abutting segments 56 (FIG. 4). Each segment 56 comprises a section of a metallic sealing ring 58 and a section of a resilient cushioning body 60, 60'.

Ring 58 is fabricated from spring steel plate material and is formed to the shape illustrated in the drawing (FIG. 8 in particular). Ring 58 possesses a mounting or fixed edge portion 62 that is firmly secured to the inner sur face of the tail section 14, in a manner to be hereinafter described; a relatively flexible free edge portion 64 having a seal surface in sliding engagement with the outer surface of lining L; and an intermediate portion 66 interconnecting said mounting and

free edge portions

62, 64, re spectively. As perhaps best shown by FIGS. 2 and 5, the free edge portion 64 is offset radially inwardly from the mounting portion 62 relative to the tail sect-ion 14. The intermediate and

free edge portions

66, 64, respectively, are slotted (FIG. 6, for example), and the slots (some of which are designated 68) open rearwardly and extend generally parallel to the centerline axis SA (FIGS. 1 and 4) of the ring 58. The slots 68 divide the intermediate and

free edge portions

66, 64 of the ring 58 into a plurality of relatively flexible fingers, some of which are designated 70.

The circumference of ring 58 in the region of the free edge portion '64 is smaller than the circumference of said ring 58 in the region of the mounting portions 62. Due to this difference in circumference, the rear portion of the fingers 70 are spaced closer together than the forward portion of such fingers 70, and the slots 68 between the fingers 70 are narrower in their rear portions than they are in their for ward portions. The tunnel lining L is not perfectly cylindrical, but rather varies slightly in diameter and circumference throughout its length. Consequently, as the shield moves forwardly during the tunneling operation, with the seal surfaces of the fingers 70 in sliding contact with the tunnel lining L, each finger 70 is moved either radially inwardly or outwardly depending upon whether the radius of the tunnel lining along its line of contact with the same increases or decreases during lineal travel of such finger 70. At the same time, the spacing between the fingers varies. However, as 'will be evident, sealing contact of the free edge portion 64 is essentially always maintained, owing to the flexible nature of ring 58 where it contacts the lining L. The pressure exerted by the cushioning body 60, 60' substantially conforms the free edge portion of ring 58 to fit the configuration of the outer surface of lining L.

As shown by FIGS. 2 and 5, the

resilient cushioning body

60, 60 substantially fills the space between the intermediate portion 68 of ring 58 and the adjoining surface portion of tail section 14. The cushioning

body

60, 60 is shown to possess a generally triangular (or wedge-shaped) cross-sectional configuration, with the apex being directed forwardly and extending substantially to where the intermediate and mounting

portion

66, 62, respectively, of the ring 58 are joined.

According to the present invention, one form of the cushioning body 60 comprises an air bladder section associated with each section of the metallic ring 58. In FIGS. 2 and 3,

air supply pipes

74, 76 are shown to extend rearwardly from a source of compressed air in the cutterhead support CS, through a gap formed between the closed ends of a pair of adjacent air bladder sections of the forward pressure seal ring PS, and to be connected at their respective aft ends, each to a separate one of a pair of adjacent air bladder sections of the rearmost pressure seal ring PS.

As shown by FIG. 2, each air bladder section comprises an inner (radially considered) wall 78, an outer wall 80, .and an interconnecting rear wall 82. It also includes two end walls which are not shown. The forward edge portions of walls 78, 80 meet to form the aforementioned apex. The rear wall 82 extends between and interconnects intermediate portions of the walls 78, 80 at a location which is closer to the rear edges than to the front edges of the said 'walls 78,80. Outer wall 80 is not secured to the inner surface of tail section 14, but inner wall 78 is preferably bonded to the outer surface of metallic ring 58 (FIG. 2).

FIGS. 5 and 11 illustrate a modified form. of cushioning body 60'. It is fabricated from a flexible foam plastic. Referring to FIG. 11, the foam cushioning member 60' may comprise a core 84 of open cell urethane foam, or the like, covered by

layers

86, 88, 90 of open cell neoprene foam. A casing 92 of impervious (waterproof) sheet neoprene, for example, covers and is bonded to the rear wall portion of the body 60', which portion would be otherwise exposed. The remaining outer surfaces of the cushioning body 60' are preferably either covered with the same material or are painted with a suitable waterproofing material, so .as to seal them against the ingress of water.

The open cell plastic material soaks up water like a sponge, and hence the waterproof casing must be provided. Closed cell plastics are substantially waterproof, but are not preferred materials to use in making cushioning body 60', because they tend to set or take a definite shape under load. The open cell foam materials absorb water but are resilient and will recover their original shapes when the load on them is released. The end surfaces of the sections of cushioning body 60' are preferably not sealed. This is so that any water that does find its way into such sections can escape at the ends of such sections.

Two types of open cell plastic material are used for the following reasons. Referring to FIG. 5, for example, during some stages of the tunneling operation the tail section 14 may be moved toward the tunnel lining L until actual to the combined thicknesses of the bar 110 and the the outer surface of the tunnel lining L. In the region where this happens the cushioning body 60' must be capable of squeezing down into a space substantially equal to the combinned thicknesses of the bar 110 and the members 108. It is also desirable that the cushioning body be tough in its marginal portions. The neoprene foam is sufficiently tough, but will not compress to the extent desired. The urethane foam, or the like, will compress sufficiently, but it lacks the desired toughness characteristics. The use of neoprene and urethane (or the like) foam together, in the manner illustrated and described, results in a composite cushioning body that is compressible to the extent desired (due to the relatively large core 84 of the material having good compression characteristics), and also has the desired toughness in its marginal portions (owing to the tougher of the two materials, i.e. the mo prene, being used to form the marginal portions). The spring steel for the ring 58, and the foam material for the cushioning body 60', are chosen so as to be capable of being deformed into a space that is substantially equal to the combined thicknesses of the bar 110 and members 108, and then recovering to substantially their original shapes when the load on them is released. The bar 110 prevents further deformation of the seal segments, and hence serves to protect and prevent destructive crushing of such segments.

As clearly shown by FIGS. 5 and 11, the modified form of cushioning body 60 also possesses a generally triangular or Wedge-shaped cross-sectional configuration, and the inner surface of each section of such cushioning body 60' is preferably bonded to the outer surface of the section of ring 58 with which it is associated. Preferably also, a sheet 93 (FIG. 5) of an impervious material, such as sheet neoprene, for example, is bonded to the outer surface of each section of ring 58, and then the cushioning body is bonded to the sheet material 93. The sheet material 93 forms a dam to fluid flow from the open cells of body 60 radially inwardly through the slots 68.

A trailing portion 94 of casing 88 is bonded to the outer surface of the free end portion 64 of ring 58, as is shown by FIG. 5. As also shown by FIG. 5, the casing 92 extends from the inner surface of tail section 14 down to the outer surface of the free edge portion 64 of ring S3. The rear portions of the slots 68 are preferably filled with neoprene putty or a similar type waterproofing material, as indicated at 96 in FIG. 6.

Cushioning body 60 (in like fashion as body 60 discussed above) urges the fingers toward the tunnel lining L and in that manner maintains the seal surface, i.e. the inner surfaces of the fingers '70 in the region of the free edge portion 64, in sealing contact with the outer surface of lining L. Regardless of the form of cushioning body, the metallic ring 58 and the cushioning body 60, 60' together form a substantially impervious Wall or barrier between the tail section 14 and the tunnel lining L.

The manner of attachment of the seal ring segments will now be described. As clearly shown by FIGS. 6 and 8, the mounting edge portion 62 of the metallic ring member 58 is cut away so as to form a plurality of forwardly extending tongues 100. A spacer bar 102 extends ontboardly of and is secured to the metallic ring member 58, as by rivets 104, for example. Forwardly opening blind slots 106 may be cut into both the spacer bar 102 and the recessed parts of mounting portion 62 situated between the tongues 100, for a purpose to be hereinafier described.

A plurality of tongue engaging sockets are formed on the inner surface of tail section 14. The sockets may be formed by welding a series of circumferentially spaced blocks 108 to the inner surface of tail section 14. The blocks 108 are of substantially the same thickness as the bar 102. A retainer bar 110 is Welded to the inner surfaces of said blocks 108. Such retainer bar 110 spans or bridges across the spaces between the blocks 108, enclosing such spaces, and the enclosed spaces so formed become the tongue engaging sockets. A bolt or stud 112 is threaded into the tail section 14 at a location immediately rearwardly of each block 108 (FIG. 6). The diameter of the shank portion of each such bolt 112 is small er than the width of the blind slots 106. A washer 114 is associated with each bolt 11?... The washers 114 are substantially larger than the slots 196.

As previously mentioned, each pressure seal segment is individually installed and individually removed from its place inside tail section 14. The installation involves sliding the tongue portions into the sockets formed by the blocks 108 and the retainer bar 110. The arrangements of the tongues 100, the tongue engaging sockets, the bolts 112, and the slots 106, is such that when the tongues 100 are engaged by the sockets, the shank portions of the bolts 112 are engaged by the slots 106.

A wedge 116 (FIG. 10, for example) is driven between the outer surface of each tongue 100 and the adjoining inner surface of the tail section 14. The wedges 116 enter into the slots from the end thereof opposite the end through which the tongues 100 enter. The bolts 112 associated with a given segment of a pressure seal PS are tightened when such segment is in place. This causes the washer 114 to clamp against the mounting portion 62 of the metallic seal member 58. The wedges 116 may be provided with one or more set screws 118. When the wedges 116 are in place, the set screws 118 may be screwed into the wedges for the purpose of increasing the effective depth, and hence the wedging action, of the wedges 116.

The bolt and

washer assemblies

112, 114 and the wedges 116 together serve to firmly and rather rigidly secure or fix the said mounting portion 62 onto the tail section 14, but in a manner such that the seal segments can be easily and readily removed.

Preferably, the forward ends of the tongues 100 are curled inwardly, a convex forward edge is formed on the retainer bar 110, and a concave surface is formed on each wedge 116 in the region where the same contacts the said curled edge portion of a tongue 100.

According to the invention, the dirt seal DS is also of sectional construction, and each of its sections is secured to the tail section 14 in essentially the same manner as a segment of the pressure seal PS is secured thereto. Referring to FIGS. and 12, the dirt seal DS may also include a metallic member 120 of spring steel plate having a mounting or fixed edge portion 122, a free edge portion 124, and an interconnecting intermediate portion 126. The metallic member 120 of each section of the dirt seal DS may be formed so as to be identical in configuration with the metallic member of the pressure seal segments 56. Thus, the mounting portion 122 of such metallic member 120 is formed to include a plurality of forwardly projecting tongues, recesses between the tongues, and forwardly opening blind slots in said recesses. Further, the intermediate and free edge portions are slotted so as to divide such portions into relatively flexible fingers. Tongue engaging sockets, identical with those described above in connection with the pressure slots PS, are provided on the inner surface of tail section 14 for the dirt seal sections. Also, wedges and bolt and washer assemblies are used in conjunction with such sockets for securing the dirt seal sections in place.

Referring to FIG. 12, a sheet 127 of an impervious material, such as sheet neoprene, for example, is shown to be bonded to the inner surface of the metallic member 120 in the region of the intermediate and

free edge portions

126, 124, respectively (like sheet material 93 on ring 58). Neoprene putty may be used to fill the slots between the fingers in the region of the free edge portion 124. A circumferentially extending strip 128 of a closed cell plastic foam may be bonded to the outboard side of each member 120 in the region immediately rearwardly of the spacer bar 130 associated therewith. The foam material strip 128 should initially be substantially thicker than the spacer bar 130. Closed cell foam material is used at this location because a waterproof barrier is desired, and the fact that the foam material sets or takes a definite shape under load does not matter.

The dirt seal DS functions to prevent the ingress of rocks and large particles of dirt into the annular region between the tail section 14 and the tunnel lining L. The pressure seals PS serve to hermetically seal such annular space against the leakage of compressed air and water under pressure from the region immediately surrounding the shield S, through said annular space between the tail section 14 and the tunnel lining L, and into the interior of the tunnel which is substantially at atmospheric pressure. In some installations it may be necessary to employ two or more pressure seals PS, in which case the rearward pressure seals PS serve to subdivide the pressure drop between the outside and the inside of the tunnel, thus breaking the force that determined the leakage of air and water, and the forward seal essentialy prevents any leakage at all.

The outer surface of the tunnel lining L is relatively rough and abrasive to the seal surfaces of the pressure seals PS and the dirt seal DS. As a result, the pressur seals PS and the dirt seals DS do wear out and must be periodically replaced during the tunneling operation. In order to replace the seal segments or sections, the shield S is moved forwardly an amount sufficient to provide access to the wedges and bolt and washer assemblies, and to permit the amount of rearward movement of the segments or sections that is necessary to their removal. The bolts 112 are backed out, and the wedges 116 are removed. Next, the seal segment or section is slid rearwardly and removed, after which a new segment or section is put in its place. Then, the wedges 116 returned, and the bolts 112 again tightened. This manner of securing the seal segments or sections in place does not require a precise alignment of a series of openings in the seal segment or section with a corresponding series of Openings in the tail section 14, which would be the case if the seal segments or sections were merely bolted to the tail section 14. Also, such a bolting arrangement would be unsatisfactory because mud, grout, etc. is present in the region of the seal rings, and once a bolt is completely removed from its opening in tail section 14, such opening becomes filled and is practically impossible to relocate. Even if found, the bolt could not be again tightened because of the mud, etc. in the hole.

As clearly shown by FIG. 9, the washers 114 are preferably formed to include a beveled edge surface arranged so that the leading edge of the seal segment or section, in the region of a recess between an adjacent pair of tongues, will strike such beveled surface 130 and cause upward displacement of the washer 114. This arrangement makes it unnecessary to individually lift each of the washers 114 in order to slide the seal segments or sections into place.

From the foregoing, further variations, adaptations, modifications and characteristic features can be evolved by those skilled in the art to which the invention is addressed, within the scope of the following claims.

What is claimed is:

1. In combination, a tunnel lining; a tunneling shield tail section surrounding said lining; and a pressure seal situated between the tail section and the lining, said seal comprising: a metallic ring having a fixed edge portion firmly secured to said tail section, a relatively flexible free edge portion having a seal surface in sliding engagement with said lining, and an intermediate portion interconnecting said fixed and free edge portions, and a resilient, cushioning body substantially filling the space between said ring and said tail section, said ring and said cushioning body together forming a substantially impervious barrier to leakage between the tail section and the lining.

2. The combination of claim 1, wherein said cushioning body comprises gas filled bladder means substantially filling the space between said metallic ring and the ad jacent portion of the tail sections inner surface.

3. The combination of claim 1, wherein said cushioning body possesses a generally triangular cross-sectional configuration, with an apex situated closely adjacent where the intermeditae and fixed portions of the metallic ring meet.

4. The combination of claim 3, wherein said cushion ing body comprises gas filled bladder means.

5. The combination of claim 3, wherein said cushioning body is formed of a solid, resilient foam material.

6. In combination, a tunneling shield comprising an elongated cylindrical skin, a transverse bulkhead spanning the interior of said skin, and dividing'said skin into forward and tail sections, and means delivering compressed air to pressurize the region forwardly of said bulkhead; a substantially watertight tunnel lining trailing rearwardly of said shield and bulkhead, in a previously exacavated portion of the tunnel, the interior of which is substantially at atmospheric pressure, said tunnel lining having a forward portion extending into, so as to be surrounded by, the said tail section of the shield skin, with an annular space existing between said tail section and said forward portion of the tunnel lining; and a pressure seal situated in said space between the tail section of the shield skin and the forward portion of the tunnel lining, said pressure seal comprising at least one annular seal ring of spring steel having a relatively rigid forward edge portion, a flexible rear edge portion, and inner and outer side surfaces, means securing the said forward edge portion to the inner surface of the tail section of the shield skin, said ring curving radially inwardly towards the tunnel lining as it extends rearwardly from said forward edge portion, and an annular, resilient cushioning body situated between said outboard surface of the sealing ring and the inner surface of said tail section, said seal ring and cushioning body together providing a substantially impervious wall in the space between the tail section of the shield skin and the forward portion of the tunnel lining, functioning to substantially prevent any leakage of high pressure fluids from the region immediately surrounding the shield, through said space between the tail section of the shield skin and the forward portion of the tunnel lining, into the previously excavated tunnel rearwardly of said bulkhead which is substantially at atmospheric pressure. I

7. The combination of claim 6, wherein said cushioning ring comprises a gas filled bladder means of resilient material.

8. The combination of claim 6, wherein said cushioning ring comprises a solid body of a resilient foam material.

9. The combination of claim 6, wherein said cushioning ring comprises a body of an open cell foam material, and includes an impervious covering for said body.

10. A tail section seal for a tunneling shield comprising: a sectional ring formed of spring steel plate and composed of a series of circumferentially abutting sections, each section having a mounting portion, a free edge portion ofiset radially inwardly from said mounting portion, and an intermediate portion interconnecting said mounting and free edge portions, with said free edge and intermediate portions being slotted, and with the slots extending axially of the ring and dividing said free edge and intermediate portions into a series of circumferentially spaced fingers, whereby free edge portion is relatively flexible; and a segmented, annular cushioning body composed of a series of circumferentially abutting segments, with each of the segments being located radially outboardly of a related one of the sections of said ring.

11. In combination, a tunneling shield including a cylindrical tail section having an inner surface and a series of sockets spaced around said inner surface; and a seal extending around the inner surface of said tail section, said seal including a mounting portion having a plurality of tongues insertable into said sockets, and means for removably securing said tongues in said sockets.

12. In combination, a tunneling shield including a cylindrical tail section having an inner surface and a series of sockets spaced around said inner surface; and a seal ring extending around the inner surface of said tail section, said seal ring being formed of spring steel plate and comprising a mounting portion, a free edge portion offset radially inwardly from said mounting portion and said tail, and an intermediate portion interconnecting said mounting and free edge portions, with said free edge and intermediate portions being formed to include slots extending axially of said ring, said slots making said free edge portion relatively flexible, said mounting portion being formed to include a plurality of tongues insertable into said sockets, and means for removably securing said torl'gues in said sockets.

13. The combination of claim- 12, wherein a spacer bar extends around the inside of said tail section between it and the mounting portion of said seal ring, and is secured to said mounting portion, and wherein a resilient cushioning body is situated between the tail section and a relatively small part of the intermediate portion of said seal ring in the vicinity of said spacer bar.

14. The combination of claim 12, wherein a spacer bar extends around theinside of said tail section between it and the seal ring, and wherein a resilient cushioning body occupies and substantially fills the space between the tail section and the intermediate portion of said seal ring, said body being substantially triangular in crosssection and having an apex disposed adjacent said spacer bar.

15. The combination of claim 14, wherein said cushioning body is formed of a resilient foam material.

16. In combination, a tunneling shield including a cylindrical tail section having an inner surface and a series of sockets spaced around said inner surface; and a seal extending around the inner surface of said tail section, said seal including a mounting portion having a plurality of tongues insertable into said sockets, and means for removably securing said tongues in said sockets, with said sockets being formed by a plurality of blocks spaced around the inner surface of said tail section, and a relatively narrow bar bridging across and enclosing the spaces between said blocks, the enclosed spaces constituting the sockets, and with the means for removably securing said tongues in said sockets comprising wedge means insertable between each tongue and the adjoining portion of the inner surface of said tail section.

17. In combination, a tunneling shield including a cylindrical tail section having an inner surface and a series of sockets spaced around said inner surface; and

, a seal extending around the inner surface of said tail section, said seal including a mounting portion having a plurality of tongues insertable into said sockets, and means for removably securing said tongues in said sockets, with said mounting portion being provided with blind slots between said tongues, said slots opening in the direction in which the tongues extend, and with a clamping post standing out from the inner surface of said tail section in the path of each blind slot, each said post carrying clamping means that is larger in width than the blind slot, and which rests against the surface of said mounting portion in the vicinity of the slot.

References Cited UNITED STATES PATENTS 1,182,626 5/1916 Benedict 49494 3,108,852 10/1963 Olsen 49485 3,167,827 2/1965 Alley et a]. 49482 3,266,257 8/1966 Larrouze et al. 61--85 JACOB SHAPIRO, Primary Examiner.