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Publication numberUS3266257 A
Publication typeGrant
Publication dateAug 16, 1966
Filing dateMay 31, 1963
Priority dateMay 31, 1963
Also published asDE1459879B1, DE1534660A1, DE1534660B2, DE1534660C3, DE1534661A1, DE1534661B2, DE1534661C3, DE1658757A1
Publication numberUS 3266257 A, US 3266257A, US-A-3266257, US3266257 A, US3266257A
InventorsGesta Pierre F, Goussault Pierre J M, Larrouze Raymond J L, Robbins Richard J, Winberg Douglas F
Original AssigneeRobbins & Assoc James S
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Shield tunneling method and mechanism
US 3266257 A
Images(10)
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Description  (OCR text may contain errors)

g- 1966 R. J. L. LARROUZE ETAL 3,266,257

SHIELD TUNNELING METHOD AND MECHANISM 10 Sheets-Sneet 1 Filed May 1, 1963 6m ATiO/PN KS Aug. 16, 1966 R. J. L. LARROUZE ETAL 3,266,257

SHIELD TUNNELING METHOD AND MECHANISM 10 Sheets-Sneet 2 Filed May 5], 1963 E E E E E E I l..- ATYLORN Y6 1956 R. J. L. LARROUZE ETAL 3,266,257

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Aug. 16, 1966 R. J. L. LARROUZE ETAL 3,

SHIELD TUNNELING METHOD AND MECHANISM 1O Sheets-Sheet 5 Filed May 5], 1963 INVENTORS. 4 YMOA/D a. l. Mfikaazs Makes E 6557?! Mae/e5 a. wax/10a 0006-245 F. via/V6996 R/cV/AED dzoas/lva Arr GEN V5 g- 6, 1966 R. J. LARROUZE ETAL 3,266,257

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SHIELD TUNNELING METHOD AND MECHANISM Filed May 51, 1963 10 Sheets-Snet 7 Aug. 16, 1966 R. J. L. LARROUZE ETAL 7 SHIELD TUNNELING METHOD AND MECHANISM 10 Sheets-Sheet 8 Filed May 31, 1963 Aug. 16, 966 R. J. L. LARROUZE ETAL 3,266,257

SHIELD TUNNELING METHOD AND MECHANISM 10 Sheets--$heet 9 Filed May 3], 1963 f MW 0 m TA A0088 m n 2% f we az N Z 0 M e i "fix sham Y B NTTUZ/Y g- 1966 R. J. L. LARROUZE ETAL 3,266,257

SHIELD TUNNELING METHOD AND MECHANISM Filed May 3.], 1963 10 Sheems-$neet 1O United States Patent 3,266,257 SHIELD TUNNELING METHOD AND MECHANISM Raymond J. L. Larrouze, Neuilly sur Seine, Pierre F. Gesta, Montessori, and Pierre J. M. Goussault, Paris, France, and Douglas F. Winberg, Bellevue, and Richard J. Robbins, Seattle, Wash., assignors to James S. Robbins and Associates, Inc., Seattle, Wash, a corporation of Washington Filed May 31, 1963, Ser. No. 284,604 24 Claims. (Cl. 61-85) The present invention relates to the art of tunneling or tunnel mining, and more particularly relates to a shield and compressed air tunneling technique and equipment for practicing same wherein the tunneling operation, simply stated, comprises propelling a shield mounted rotary cutterhead forwardly into the tunnel face while rotating the same, delivering compressed air to the tunnel face region forward of a transverse bulkhead and cutterhead support portion of the shield, constructing a lining for the tunnel in the wake of the cutterhead and under the protection of the shield, removing the mined material from the cutterhead region through a material lock extending rearwardly of the bulkhead and emptying into a conveyor in the non pressurized tunnel, and hermetically sealing the pressurized zone at the face of the tunnel and in the material compartment from the rest of the tunnel situated rearwardly of the bulkhead, including sealing against leakage between the tail section of the shield and the tunnel lining.

It is now common practice in shield tunneling operation to establish the bulkhead at or adjacent to the portal of the tunnel and then pressurize the entire tunnel. The workmen in the tunnel are continuously exposed to a compressed air atmosphere while they are working and are in constant danger of contacting the illness called compressed air sickness, caisson disease, divers palsy or the bends. The cause of compressed air sickness is that: the blood passing through the lungs is in contact with a wet film of protoplasm which, in its turn, is in contact with the air breathed. The blood takes up the gases of the air in solution and, if exposed to compressed air, will dissolve oxygen and nitrogen in an amount increased proportionally to the pressure. The oxygen gas thus taken up, under the ordinary conditions of engineering work in compressed air, has no harmful effect on the body. The trouble is due to the nitrogen gas which is taken in solution by the blood. While a man continues at work in the compressed air no hannful effects are felt. If reduction of pressure occurs too rapidly the nitrogen held in solution in the blood is set free in the form of bubbles. These bubbles are taken to the various tissues. It is wellknown that the longer the exposure to the compressed :air, the greater the chance of contacting compressed air sickness.

It is a principal object of the present invention to provide a tunnel mining technique and equipment for practicing same which permits at least most of the workmen to work in the tunnel in an unpressurized atmosphere, and which shortens considerably the exposure of the remaining workmen with the compressed air. At the same time, the technique and equipment of the present invention provides for faster and more efiicient tunnel mining than has heretofore been the case.

Shield tunneling involving the general propostion of positioning a shield mounted bulkhead adjacent the face of the tunnel, and then pressurizing the face region while leaving the portion of the tunnel situated rearwardly of the bulkhead unpressurized, is known. However, the prior mechanism involving this technique employs no rotary cutterhead, but rather the mining is performed by hand operated excavators. Also, in such prior technique involving excavating ahead of the bulkhead by means of Patented August 16, 1966 hand operated implements, the operation involving movement forward of the shield and erection of new rings of the tunnel lining behind the shield is intermittent in nature. The shield is moved forward an amount equal to the width of a ring and is then stopped and an entire new ring erected, after which the shield is driven forwardly again.

It is also known generally that in the original designs for the shields for the Blackwall tunnel, the Pennsylvania tunnels under the East River, and the Spree tunnel, a second bulkhead was to be situated generally adjacent the face of the tunnel and access to the face was to be through airlocks, with the usual set of double doors, extending through the bulkhead. The purpose was to make it possible to use a higher pressure in part or all of the face than in the tunnel. Shields were not used on these projects, however, as it was believed at the time of their design that in practice certain portions of these shields would prove unworkable. Also, these shields involved hand mining techniques by men stationed in the space between the forward bulkhead and the face of the tunnel.

Objects, features and advantages of the present invention involve the provision of a shield and compressed air tunneling method and mechanism wherein:

(a) The tunneling operation involves propelling a shield mounted rotary cutterhead into the face of the tunnel, delivering compressed air to the face region of the tunnel contiguous the cutterhead, and hermetically sealing the pressurized zone at the face of the tunnel from the main portion of the tunnel located rearwardly of the cutterhead and shield;

(b) The shield includes a generally cylindrical skin and a transverse cutterhead support spanning the interior of said skin, with a generally disk-shaped cutterhead with buckets being rotatably mounted onto the front face of the cutterhead support, and with the cutterhead support in part consisting of a transverse bulkhead;

(c). The shield and rotary cutterhead carried thereby are moved forward by means of hydraulic jacks or rams attached to the shield structure and reacting against the tunnel lining previously erected, with said jacks or rams being circumferentially spaced around the periphery of the cutterhead support and being offset from the rear face of the cutterhead support by progressively increasing amounts proceeding from bottom to top, with what may be termed a stairstep arrangement of the jacks or rams allowing simultaneous movement forward of the shield and cutterhead assembly and erection of a new ring of tunnel lining substantially in the wake of such assembly, but under cover of the tail section of the shield skin;

((1) The cutterhead support is characterized by a cellular interior construction, forming separate interior compartments that can be isolated from each other, from the pressurized regions, and from the unpressurized portion of the tunnel, to be pressurized and depressurized on an individual basis, such compartments including cylinder compartments, gear box compartments, and service air locks, with the cylinder and gear box compartments functioning to allow removable of various pieces of equipment from openings in the cutterhead support without depressurizing the entire pressurized region forward of the cutterhead support and within the material compartment, and with the service lock permitting access from the unpressurized tunnel to the pressurized region contiguous to the cutterhead, for example, without such tot-a1 depressurization occurring;

(e) The cutterhead support assembly is provided with seal means sealing against pressure leakage and dirt travelling into the region of the cutterhead bearing and the pinion bull gear assembly forming a portion of the driving mechanism of the cutterhead, such sealing means also assisting to prevent total depressurization of the system when a motor unit is removed from its gear box compartment, leaving an opening in both faces of the cutterhead support;

(f) The tunneling machine includes a material compartment anchored at its forward end to the cutterhead support and at its rearward end on rolling carriage means riding on extendible rail means, with such material compartment communicating at its forward end with the cutterhead region through an opening in the cutterhead support and also containing interiorly arranged conveying means for transporting mined material received from the cutterhead chutes from the front to the rear of such compartment to be deposited in hopper means at such rear end location, forming a material lock for disposition of the mined material from the material compartment without depressurizing the same; and

(g) The material compartment includes a conveyor tube of suflicient height for a man to walk therein and such conveyor tube, besides containing material conveying means, includes a longitudinally extending walkway and means between said walkway and the conveyor means for preventing material spillage onto said walkway, thus assuring the safety of persons using the walkway, with access to the conveyor tube being had through a man lock leading into a side portion thereof.

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 cutterhead and the cutterhead support presented in longitudinal section;

FIG. 2 is a view similar to FIG. 1, with the outer boundary of the pressurized region identified by a bold broken line;

FIG. 3 is an elevational view of the front face of the cutterhead, with parts of such cutterhead broken away to show the bull gear that is attached to the rear side of the cutterhead in mesh with two of the pinion gears which drive the same;

FIG. 4 is a fragmentary, longitudinal sectional view of a typical seal arrangement usable between the tail section of the shield skin and the previously erected portion of the tunnel lining contiguous thereto;

FIG. 5 is a fragmentary end elevational view of the shield seal of FIG. 4, taken substantially along line 5-5 of FIG. 4;

FIG. 6 is a top plan view of the shield tunneling machine shown in FIG. 1, with the erectors removed and with the erector tube broken away above the receiving conveyor for clarity of illustration;

FIG. 7 is an exploded side elevational view of the shield and the cutterhead, with the ram pedestal portion of the shield being presented in longitudinal section so as to fully illustrate the stepped arrangement of the cylinder supports;

FIG. 8 is an enlarged scale sectional view of the hearing and seal means located between the rotary cutterhead and the stationary cutterhead support;

FIG. 9 is a cr'os-sectional view of FIG. 1, taken substantially along line 9-9 of FIG. 1, such view showing the rear wall of the cutterhead support;

FIG. 10 is a cross-sectional view taken substantially along line 1010 of FIG. 1, presenting a rear view of the hopper assembly and the support means therefor, and also presenting a cross-sectional view of the tunnel conveyor which receives the mined material from the hoppers and carries it out of the tunnel;

. FIG. 11 is a view looking toward the rear side of the assembly comprising the cutterhead support and the ram pedestal, with the bulkhead or rearmost wall of such assembly removed to present a clear illustration of the compartments involved in said assembly;

FIG. 12 is an enlarged scale fragmentary sectional view 4 taken substantially at line 12-12 of FIG. 10 and illustrating typical means for pressurizing and depressurizing a given single compartment of the group of compartments, a cylinder compartment being chosen for sake of example; and

FIG. 13 is a cross-sectional view taken through the conveyor tube substantially at line 1313 of FIG. 1, such view illustrating the walkway for the service personnel, the location of the conveyor within the tube, and a pro tective shield arranged between said conveyor and the walkway.

Referring now to the figures of the drawings 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, which is conventional per se; 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 face 16 of the cutterhead support CS, preferably by means of an annular bearing 18, as is hereinafter explained more fully.

As clearly shown in FIG. 3, the front face of the cutterhead C is provided with appropriate knives or cutters, some of which are designated 20 for sake of example. The cutters 20 are placed at different distances from the center of the cutterhead C, and when the cutterhead C revolves such cutters 20 cut concentric grooves in the face of the tunnel, resulting in a complete 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, some of which are designated 22 in FIGS. 1, 3 and 8, for example, which mesh with the large bull gear 24 forming an integral part of the inner race 26 of the annular bearing 18. The said 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, one of which is designated 28 in FIG. 8. The motive power is furnished by a plurality of motors M, a particularly advantageous number thereof being ten, arranged with four above and six below a horizontal center line.

A plurality of buckets B (FIG. 3, for example), are circumferentially arranged about the cutter carrying portion of the cutterhead C. Generally speaking, the buckets B open in the 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 the tunnel. The buckets B have radially inwardly extending discharge chute portions, one of which is shown at 30 in FIG. 1, discharging the mined material onto a receiving conveyor 32 located within an opening or passageway 34 extending through cuterhead support CS. A deflector 34 is used to guide the mined material onto the conveyor 32. The conveyor 32, which is preferably constructed of metal pads linked together so as to be durable and able to resist the shock of the mined material falling on it from the chutes 30, feeds the mined material onto a longer conveyor 36 comprising an endless belt constructed of rubber or similar material. Conveyor 36 is encased partially within an erector tube 38 and partially within a conveyor tube 40 extending rearwardly out of said erector tube 38 to communicate at its rearmost end with a hopper dome 42. An appropriate seal, suitably in the form of a flexible annular collar 44, interconnects between erector tube 38 and conveyor tube 40. Within the enclosure of the hopper dome 42, conveyor 36 deposits the mined material into one. or the other of a pair of discharge hoppers H1, H2, the physical makeup and function of which are hereinafter discussed. Erector tube 38, conveyor tube 40, hopper dome 42 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.

A forward extension 46 of conveyor tube 40 is universally mounted within the enclosure of erector tube 38 onto cutter support CS at the location designated 48 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 a 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 segments during erection of each new ring. The erector arrangement and the particular type of erector mechanism employed is not critical to the present invention, but the twin erector assembly disclosed and claimed in the copending application of Douglas F. Winberg, entitled Segment Erectors and Universally Mounted Conveyer Tube Means for a Tunneling Machine, Serial No. 284,710, filed May 31, 1963, is preferred and such is illustrated, such erectors being designated E1, E2 in the drawings.

The shoving, driving, or moving forward of the shield S and the rotary cutterhead 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. In accordance with the present invention, the hydraulic rams R are circumferentially spaced around the periphery of the cutterhead support CS contiguous the inner surface of tail section 14. The lowermost pair of rams R are 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 each side thereof, with the topmost three rams R being offset the most and by equal amounts. In the machine illustrated thirty-seven hydraulic rams R are employed. Of course, it is to be realized that the number of rams and their arrangement can be modified somewhat Without departing from the spirit of the present invention, the important factor being the stairstep arrangement of the hydraulic rams R, and the function performed by such arrangement, which is presently to be described.

Heretofore, during the construction of a shield driven tunnel, when the erection of a ring of the tunnel lining has been completed and the excavation for the next ring width has been carried out, the shield is advanced a distance equal at least to the width of a ring so that the erection of another ring may proceed. That is to say, all of the hydraulic rams in known prior machines are mounted in the same vertical plane and they all became fully extended at substantially the same time. In the driving operations of such prior machines, adjacent extended pistons in sets of three, for example, are retracted into their cylinders leaving a space between the rearwardly directed faces of the retracted pistons and the forwardly directed side of related portions of the last erected ring of the tunnel lining into which a new segment is placed. This procedure is repeated with respect to the next set of adjacent rams and so forth around the inside of the tunnel until the ring is completed. The pistons are again extended and the shield advanced an additional amount. This procedure of intermittently moving forward and stopping, and erecting a new complete ring of the tunnel lining during each stoppage period can be satisfactorily employed with prior art machines which do not involve a rotating mechanical excavator, but which instead involve workmen chipping away at the face of the tunnel with hand implements or small, hand-operated power excavators. However, the most advantageous operation of the tunnel machine of the present invention, employing a rotary cutterhead, includes continuously moving such cutterhead C forwardly without stoppage, and the ram pedestal arrangement (the ram pedestal is designated RP in FIG. 7) of the present invention makes this operation possible. Because of the stairstep arrangement of the cylinder supports P1-P37 (FIG. 7), the pistons are always extended by varying amounts circumferentially around the tunnel. Except in the case of the topmost three rams R, which are offset an equal amount, by virtue of the stairstep arrangement, symmetrically related to a vertical center line, only two of the pistons become fully extended at the same time. The remaining pistons still have some outward travel to go and may still be utilized for shoving the shield S and the cutterhead C forwardly. The first two pistons to become fully extended are retracted While the remaining pistons are still shoving. This procedure is repeated with the next vertically adjacent pair of pistons and so forth up each side until voids large enough to accommodate a ring segment are formed on both sides of the tunnel. Segments for forming a new ring of the tunnel lining are then placed in such voids while the remaining pistons continue to move the machine forwardly. Due to the fact that the rams R are stairstepped outwardly from the rear face of cutterhead support CS from the bottom up, the first two pistons to becomefully extended are the bottom-most two, the cylinders of which are mounted flush with the rear surface of cutterhead support CS. Then moving progressively up each side from said bottom pair of rams R, the pistons of the other rams R successively reach the end of their throw and can be retracted so that additional segments can be put in place. Thus, each new ring of the tunnel lining is commenced at the bottom of the tunnel and is symmetrically erected up from there along each side of the tunnel until the last segment, the key segment, is set in place. All the time during this operation the shield S and the cutterhead C arebeing shoved forwardly by the thirty or thirty-one hydraulic rams (figuring from a basis of the thirty-seven ram arrangementdisclosed and a set of three adjacent retracted rams per segment, for sake of example) that are not retracted but are still Working. By using the twin erectors disclosed in the aforesaid copending Win'berg application Serial No. 284,710, segments are set in place on both sides of the tunnel at once, but when a conventional erector assembly is employed, i.e. one having a single erector or segment handling means, the bottom segment is put in first, then the next segment on one side and then the next on the other, with this alternation going on until the key is reached.

The means used for transporting the tunnel lining segments from the surface work site to a location within the reach of the segment erectors E1, E2 can be conventional per se, such as the overhead rail and carriage assembly 52 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.

Referring now to FIG. 2, the regions or zones that are pressurized, in accordance with the teachings of the present invention, are shown outlined by the bold broken line designated PB (pressure boundary). As is evident, only the compartment comprising erector tube 38, conveyor tube 40, hopper dome 42 and the hoppers H1, H2 through which the mined material is removed from the face of the tunnel; the interior of the cutterhead support CS, and the region between the cutterhead support CS and the tunnel face are under pressure. The tunnel itself to the rear of the cutterhead support CS and enclosed by the lining L is open throughout and communicates at its portal or entrance end with the atmosphere. Thus, except in those regions enclosed by the bold line PB, the various tunneling operations are conducted at atmospheric pressure. The rear wall 54 of the assembly consisting of the cutterhead support CS and the ram pedestal RP forms a bulkhead between the pressurized and unpressurized regions. Airtight seals interconnect between the motors M.

and bulkhead 54 and also between the ram cylinders and bulkhead 54. The connection of erector tube 38 to cutterhead support CS is also airtight, and of course the large 'seal 44 interconnecting between erector tube 38 and con veyor tube 40 is a pressure seal. As shown in FIG. 2, hoppers H1, H2 each include an upper door 56 and a lower door 58. Each of such doors 56, 58 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 SS is also provided between tail section 14 and the outside of the tunnel lining L at the region where such tail section 14 overlaps the lining L. A suitable seal for this location is shown in FIG. 4 as comprising one or more rings of flexible metal fingers 60 suitably anchored on the inner surface of tail section 14 and extending outwardly therefrom to rest on the outer surface of the lining L previously erected. A generally annular or annular segmented air bladder 62 is interposed between each row of fingers 60 and the tail section 14 and when inflated serves to urge said fingers 60 in sealing contact with the outer surface of the lining L. Compressed air is delivered from a supply line within cutterhead support CS to the air bladders 62 by means of circumferentially spaced air passageways 64. The sealing arrangement between tail section 14 and lining L also includes a tail seal TS characterized by a ring of fingers 66 substantially identical in construction with fingers 60. However, fingers 66 are urged inwardly to make contact with the outer surface of lining L by means of a plurality of leaf springs 68. Such tail seal TS functions primarily as a dirt seal whereas the seals SS comprising the fingers 60 and bladders 62 function together with the other previously mentioned seals to hermetically seal the pressurized zone at the face of the tunnel and in the material removal compartment from the main interior of the tunnel, which as previously stated is at atmospheric pressure.

The compressed air used to pressurize the interior of the material removal compartment and the zone at the face of the tunnel is preferably delivered to the pressurized regions by means of sectional pipes 70, 72 (FIGS. 1, 2 and 5, for example). Such air delivery pipes 70, 72 are alternately used, with additional sections being added to the one shut down to extend it in length so as to keep up with the tunneling machine as the same moves forwardly. The couplings used to connect the compressed air pipes 70, 72 with hopper dome 42 are suitably constructed to allow the tunneling machine to move forward a distance approximately equal to one section without decoupling and without air leakage at such location.

As most clearly shown in FIG. 11, the assembly consisting of the cutterhead support CS and the ram pedestal RP is divided into compartments. FIG. 11 is a rear view of such assembly with bulkhead 54 removed. Such view shows the assembly to be divided into a plurality of cylinder compartments, four being presented by way of example, a gear box compartment for each motor and pinion gear unit, and two man locks. The cylinder compartments are bounded by inner and outer concentrically arranged walls 74, 76, respectively, and by the peripheral portion of bulkhead 54 on the tunnel side of the assembly and by frustral conical wall 78 on the tunnel face side of the assembly. The generally radially extending walls 80, 82, 84, 86, respectively, serve as end walls for the cylinder compartments CCl, CC2, CC3, CC4. Each of the cylinder compartments is constructed to be airtight when the ram cylinders are properly seated. The region immediately radially inboard of the cylinder compartments CCl, CC2, CC3, CC4, designated 88 in FIGS. 11 and 12, is in constant communication with the pressurized region at the face of the tunnel and within the material removal compartment 38, 40, 42. A pipe containing a normally open valve 92 interconnects between each cylinder compartment CCl, CC2, CC3, CC4 and the constantly pressurized region 88. In addition, each cylinder compartment CC1, CC2, CC3, CC4 is provided with a normally closed dump valve 94, each of which when open serves to communicate its cylinder compartment with the interior of the tunnel. During normal operation all four equalizing valves 92 are open and all four cylinder compartments CC1, CC2, CCS, CC4 are pressurized. When it is desired to remove a hydraulic ram (or several) from the ram pedestal to either service or replace it, the cylinder compartment in which such ram R is situated is isolated from the other pressurized regions by closing its equalizing valve 92. Such cylinder compartment is then depressurized by opening its dump valve 94 so as to release the pressurized air contained therein into the tunnel. The hydraulic ram R that is defective and in need of repair or replacement can then be removed without danger of its removal depressurizing any more of the pressurized regions. As soon as the hydraulic ram R that was removed is reseated, or another ram is installed in its place, the dump valve 94 for such compartment is again closed and the equalizing valve 92 therefor is opened to repressurize the compartment.

The gear box compartments, designated GB1-GB10 in FIG. 10, are also constructed to be individually isolated and depressurized. Gear box compartments GBl-GB4 are enclosed'on top and bottom by concentric arcuate walls 96, 98, each constituting segments of a cylinder. Gear box compartments GB5GB10 are enclosed on top and bottom by concentrically arranged, semi-cylindrical walls 100, 102, respectively. A series of radially extending walls 106426 circumferentially separate the gear box compartments GB1-GB10. When the motors M are installed in place within the gear box compartments GBl-GB10 the openings in bulkhead 54 and the front wall 16 of the cutterhead support CS are plugged by the motors 1M and the said gear box compartments G131- GB10 are essentially enclosed on all sides and are essentially airtight. Suitable pressurizing and depressurizing means, which may be identical in form to the pipe with open valve 92 and the dump valve 94 used to pressurize and depressurize the cylinder compartments, are provided each gear box compartment. Thus, through such means, during the periods that all of the motors M are seated in their places, the gear box compartments are in communication with the continuously pressurized zone 88 and are themselves pressurized. When it is desired to isolate one such compartment, taking gear box compartment GB1, for example, the pipe communicating such compartment GBl with the pressurized region 88 is closed off and the dump valve for such compartment GBl is opened, relieving the pressure in the compartment to the tunnel. The motor in such compartment is then removed to be serviced, replaced by another, etc.

Since the removal of motor M1 unplugs the opening 128 (FIG. 8) in the front wall 16 of the cutterhead support CS as well as the opening in the bulkhead 54, some means must be provided for preventing leakage of compressed air from the cutterhead region in front of the cutterhead support CS through aid opening 128, the gear box compartment GBl and the opening in bulkhead 54 into the non-pressurized tunnel. The means for preventing such leakage is illustrated in FIG. 8 and will now be described.

Referring to FIG. 8, the inner race 26 of annular hearing 18, with bull gear 24 attached, is shown securely fastened to the rotary cutterhead C by means of a series of nut and bolt assemblies 28, as previously described. The outer race 130 of the bearing 18 is suitably supported by an annular member 132, constituting part of the cutterhead C, and is securely attached to the cutterhead support CS by means of a series of nut and bolt assemblies 134, for example. In conventional manner, a series of roller type bearing elements 136 are situated between the inner and outer bearing races 26, 130, respectively. The annular bearing 18 is suitably sealed in the region between said inner and outer race elements 26, 130, respectively, to prevent air leakage occurring through the seal 18 at this location, and also to prevent dirt, etc. from entering the region of bearing elements 136. By itself, bearing 18 forms no part of the present invention and Will not be further discussed. An annular flange 138 extending rearwardly from the rear face of the rotary cutterhead C and situated concentrically inwardly of the inner race 26, defines with inner race 26 and an annular wall 140 a somewhat circular channel opening toward the cutterhead support CS and enclosing the pinion gear 22 that are driven by the motors M and in mesh with the bull gear 24. Such generally circular channel forms with the portion of the front face 16 of the cutterhead support CS that is located between said annular flange 138 and the inner race 26, a generally annular pinion gear compartment. Suitable sealing means 142 is situated between the cutterhead support CS and flange 138 to etfectively seal such location against air leakage into the generally annular pinion gear compartment at that location while the cutterhead is rotating. Outboard sealing means 144, 146, both annular in form, are provided between the rotating cutterhead C and the stationary cutterhead support CS at the location shown in FIG. 7. Sealing means 142, 144, 146 function to seal the generally annular pinion gear compartment from the pressurized region forward of the cutterhead support, and it is these seals 142, 144, 146 that prevent leakage of compressed air from the cutterhead region through opening 128 in wall 16 and the opening in bulkhead 54 when the motor M1 is removed from its compartment GBl. The seals M2, 144, 146 also prevent dirt from entering into the interior of bearing 18 and between the pinion gears and the bull gear 26. Another dirt seal 147 is preferably located radially outboard of bearing 18 generally at the periphery of cutterhead C.

One or more service locks, two being shown in FIG. by way of example, are built into the cutterhead support CS. As shown in FIG. 1, for example, each service lock SL is provided with a door D1 in bulkhead 54 and a second door D2 in the front wall 16 of cutterhead support CS. In accordance with conventional practice each of these doors D1, D2 are constructed to be tightly sealed when shut. Let it be assumed that the service lock SL is depressurized and that it is desired to communicate with the region surrounding the back side of the cutterhead C. The air pressure in service lock SL is equal to that in the tunnel so that door D1 is readily opened for entering into the lock. When in the service lock S1 the door D1 is closed and a valve (not shown) opened, which lets the compressed air into the lock. The inflow of the compressed air is continued until the pressure in the lock is equalized with that in front of Wall 16, at which time the inner door D2 is readily opened and communication with the cutterhead region effected. Returning from the air chamber the operation of the lock is reversed, but is, in principle, the same. Side and top and/or bottom doors, two such doors being illustrated for sake of example and designated D2, D3 in FIG. 1, are provided so that access can be had with inner area 88 of cutterhead support CS and/ or the cylinder compartments from the service lock SL, if desired.

The circumferentially and radially extending plates which interconnect bulkhead 54 and the front wall 16 of the cutterhead support CS, in addition to constituting the walls for the various compartments in the cutterhead support, serve as structural members for the cutterhead supports CS. It must be remembered that the cutterhead support CS must support the shield skin and somewhat prevent it from collapsing due to the radially inwardly directed forces acting on it. The cutterhead support CS also must support the weight of the cutterhead C, must bear the thrust of the cutterhead C and the thrust rams R when the tunneling machine is being driven forward, and must also support a greater part of the weight of the material compartment and the erectors E1, E2 attached thereto, noting the anchoring of the forward end of the conveyor tube 40 at point 48 onto the cutterhead support, as previously described.

As most clearly shown in FIG. 6, a man lock ML extends alongside of the conveyor tube 40 and is interconnected therewith by means of a connecting passageway 148. In conventional fashion, the man lock ML is provided with an access door and a second door 152 interposed between the man lock ML and the conveyor tube 40. The use of the man lock ML for gaining access to the pressurized material compartment from the non-pressurized tunnel involves following conventional techniques and the employement of conventional apparatus for pressurizing and depressurizing man lock ML.

The inside dimension of conveyor tube 40 is relatively large, and as most clearly shown in FIG. 13, for example, the conveyor tube 40 contains in addition to conveyor 36 a man walk MW suitably situated to one side of the conveyor 36 and separated therefrom by a screen or partition 154 of expanded metal or the like, serving to prevent the mined material from spilling over from conveyor 36 onto the man walk MW, or onto a person using the same. The man walk MW is used by service personnel working either in conveyor tube 40 itself or else in one of 7 the other portions of the material compartment, such as in the vicinity of receiving conveyor 32, for example.

By virtue of what may be termed the local pressurization feature (i.e. pressurizing only the regions contiguous the face of the tunnel and within the material compartment) of the present invention, essentially all of the workmen taking part in the tunneling operation perform their respective duties in a working area that is essentially at atmospheric pressure. For example, the erection of the tunnel lining L; the service and repair work on the erectors E1, E2, the thrust rams R and the motor units M; and the extension of lower rails 50 and the overhead monorail portion of segment conveying means 52 are all projects that are carried out within the main portion of the tunnel, located behind wall 54, which is at atmospheric pressure.

From the foregoing, various further modifications, arrangements and adaptations of the present invention will occur to those skilled in the art to which the invention is addressed, within the scope of the following claims.

What is claimed is:

1. The method of tunneling comprising moving a shield mounted rotary cutterhead forwardly into material to be mined while rotating such cutterhead, delivering compressed air to pressurize the face of the tunnel forwardly of a transverse bulkhead portion of the shield and contiguous the cutterhead, removing mined material from the cutterhead region successively through the cutterhead, an opening in the bulkhead, and a conveyor tube means hermetically sealed at its forward end to said bulkhead about the opening therein, and extending rearwardly of bulkhead from said opening to a discharge station, and hermetically sealing the pressurized zone at the face of the tunnel from the unpressurized remaining portion of the tunnel, situated rearwardly of the bulkhead,

2. In a shield tunneling operation wherein a tunnel lining characterized by axially abutting rings of circumferentially abutting segments is erected in the wake of a rotary cutterhead supported on a transverse portion of the shield, the tunneling procedure comprising mining the face of the tunnel by means of the rotary cutterhead, delivering compressed air to pressurize the region contiguous the cutterhead and the tunnel face while maintaining such region substantially hermetically sealed and thus pressurized from the pressurized lined portion of the tunnel situated rearwardly of the cutterhead support, removing the mined material from the region of the tunnel face first through the cutterhead, then through an opening in the cutterhead support, and then through a pressurized compartment connected at its forward end about the opening in said cutterhead support communicating at its rearward end with lock means through which the mined ma terial is removed without depressurizing said compartment, and driving said shield and the rotary cutterhead mounted thereon forwardly into the material to be mined by means of power rams extending rearwardly from said cutterhead support to push against erected segments of the tunnel lining.

3. In a shield tunneling operation wherein a tunnel lining composed of axially abutting rings of circumferentially abutting segments is erected in the wake of the shield, the tunneling procedure comprising mining the face of the tunnel by means of a rotary cuterhead supported on a transverse portion of the shield, delivering compressed air to pressurize the region coniguous the cutterhead and tunnel face while substantially hermetically sealing the pressurized region thus created from the portion of the tunnel situated rearwardly of the transverse portion of the shield, and erecting a ring of segments substantially immediately behind said transverse portion while simultaneously and continuously moving said shield and the rotary cutterhead mounted thereon forwardly by means of power jacks mounted around the periphery of the shield and pushing on erected segments of the tunnel lining.

4. In a shield tunneling operation wherein a tunnel lining, characterized by axially abutting rings of circumferentially abutting segments, is erected in the wake of a rotary cutterhead supported on a transverse portion of the shield, the procedure comprising mining the face of the tunnel by means of the rotary cutterhead, delivering compressed air to pressurize the region contiguous the cutterhead and tunnel face while substantially hermetically sealing such region thus pressurized from the portion of the tunnel situated rearwardly of the transverse portion of the shield, removing the mined material from the region of the tunnel face through a pressurized compartment communicating at its forward end with an opening in the transverse portion of the shield, leading to the pressurized region at the tunnel face, and communicating at its rearward end with lock means through which the mined material is removed without depressurizing the compartment, and moving said shield, the rotary cutterhead mounted thereon, the said mined material removal compartment, and said lock means forwardly by extending hydraulic jacks mounted on the shield and reacting against installed segments of the tunnel lining while simultaneously erecting a new ring of segments onto the front end of the tunnel lining.

5. A shield type tunneling machine comprising a shield including a generally cylindrical skin having a forwardly directed cutting edge and a tail section; a transverse cutterhead support spaced rearwardly of said cutting edge including bulkhead wall means and a material removal opening; a rotary cutterhead mounted for rotation on said cutterhead support, and extending forwardly of the cutterhead support to be at least partly enveloped by said cutter edge said cutterhead including a front face, cutter means on the front face for mining the tunnel face as the cutterhead rotates, and means for delivering the earth material mined by said cutterhead to said material removing opening; means for rotatably driving said cutterhead; means for delivering compressed air to pressurize the region contiguous the cutterhead and tunnel face; material removal conduit means connected to said transverse cutterhead support about the said material removal opening therein, and extending rearwardly therefrom to a discharge station; and means for hermetically sealing such pressurized region at the face of the tunnel from the unpressurized portion of the tunnel located rearwardly of the bulkhead wall means.

6. A shield type tunneling machine usable in a tunneling operation wherein a tunnel lining characterized by axially abutting rings of .circumferentially abutting segments is erected generally in the wake of the machine but under cover of the shield skin, said machine comprising a shield characterized by a generally cylindrical skin having a forwardly directed cutting edge and a rearwardly extending tail section, a transverse support portion spanning the interior of said skin intermediate the ends thereof and including a rear wall, and a plurality of pistoncylinder actuators spaced around the periphery of said rear wall, with the pistons thereof extending in the rearward direction to react against the tunnel lining previously erected and in that manner advancing the tunneling machine forwardly into the material to be mined, and a pedestal means mounting each piston-cylinder actuator onto said support portion, with at least some of the pedestal means and the actuators thereon being offset from the rear wall of the support portion by progressively increasing amounts proceeding from bottom to top, in stairstep arrangement, such stairstep arangement of .the actuators making it possible for some of said piston-cylinder actuators to shove against the segments of the last completely erected ring of segments, for some of said pistoncylinder actuators to shove against the segments of the ring then being erected, and for certain of the pistoncylinder actuators to be withdrawn to allow placement of additional segments in the lining ring then being erected, the overall arrangement allowing forward movement of the tunneling machine and simultaneous erection of tunnel lining rings.

7. A shield type tunneling machine usable in a tunneling operation wherein a tunnel lining characterized by axially abutting rings of circumferentially abutting segments is erected generally in the wake of the machine but under cover of the shield skin, said machine comprising a shield characterized by a generally cylindrical skin having a forwardly directed cutting edge and a rearwardly extending tail section, a transverse cutterhead support spanning the interior of said skin intermediate the ends thereof, and a plurality of piston-cylinder actuators mounted around the periphery of said cutterhead support with the pistons thereof extending in the rearward direction to react against the tunnel lining previously erected and in that manner advancing the tunneling machine forwardly into the material to be mined, with at least a portion of said piston-cylinder actuators being offset from the rear face of said cutterhead support by progressively increasing amounts proceeding from bottom to top, in stairstep fashion, such stairstep arrangement of the pistoncylinder actuators making possible during certain stages of the tunneling operation for some of the piston-cylinder actuators to shove against the segments of the completely erected ring of segments, for some of said piston-cylinder actuators to shove against the segments of the ring then being erected, and for the remaining piston-cylinder actuators to be withdrawn to allow the placement of at least one additional segment in said ring then being erected; a rotary cutterhead mounted for rotation on said cutterhead support and extending forwardly of the cutterhead support to be at least partly enveloped by said cutting edge; and means for rotatably driving said cutterhead.

8. A shield type tunneling machine comprising a shield including a generally cylindrical skin having a forwardly directed cutting edge and a tail section; transverse support means having a front wall, a rear wall, and a cellular interior construction, with said rear wall constituting a bulkhead; means delivering compressed air to pressurize the region forward of said transverse support means and contiguous the tunnel face; means hermetically sealing the pressurized region at the face of the tunnel from the unpressurized portion of the tunnel located rearwardly of said transverse support means; said transverse support means further comprising a pluality of interior compartments, each of which is constructed to be isolated from the others and independently pressurized and depressurized, with at least one of the said interior compartments being a service lock having access doors in both the front and rear walls of said transverse support means.

9. A shield type tunneling machine in accordance with claim 8, wherein said transverse support means rotatably support a cutterhead, said cutterhead extending forwardly of said transverse support means so as to be at least partially enveloped by the shield skin.

10. A shield type tunneling machine comprising a shield including a generally cylindrical skin having a forwardly directed cutting edge and a tail section; a transverse cutterhead support having a front wall, a rear wall, and a cellular interior construction, with said rear wall constituting a bulkhead; means rotatably supporting a rotary cutterhead forward of the said front wall of said cutterhead support; means delivering compressed air to pressurize the region forward of said cutterhead support and contiguous the cutterhead and tunnel face; means hermetically sealing the pressurized region at the face of the tunnel from the unpressurized portion of the tunnel located rearwardly of said cutterhead support; said cutterhead support also comprising a plurality of interior compartments, each of which is constructed to be isolated from the others and to be independently pressurized and depressurized, with at least one of said interior compartments being a motor compartment; and motor means mountable to extend through openings in both the front and rear walls of the cutterhead support at the location of said motor compartment.

11. A shield type tunneling machine in accordance with claim 10, wherein said machine further comprises means for preventing depressurization of the pressurized region at the face of the tunnel when the said motor means is removed from the motor compartment, leaving the said openings in the front and rear walls of the cutterhead support uncovered.

12. A shield type tunneling machine comprising a shield including a generally cylindrical skin having a forwardly directed cutting edge and a tail section; transverse cutterhead support means having a front wall, a rear wall, and a cellular interior construction, with said rear wall constituting a bulkhead; means rotatably mounting a rotary cutterhead on said cutterhead support means, said cutterhead extending forwardly of said cutterhead support means so as to be at least partially enveloped by the shield skin; means delivering compressed air to pressurize the region forward of said transverse support means and contiguous the tunnel face; means hermetically sealing the pressurized region at the face of the tunnel from the unpressurized portion of the tunnel located rearwardly of said cutterhead support means; said cutterhead support means also comprising a plurality of interior compartments, each of which is constructed to be isolated from the others and to be independently pressurized and depressurized, at least some of the compartments being motor compartments defined partly by the said front and rear walls of the cutterhead support, with openings extending through said portions of both the front and rear walls of the cutterhead support; rnotor means mountable into the motor compartments through said openings; and and means for preventing depressurization of the region contiguous the face of the tunnel when one or more of the motor means is removed from its compartment, leaving the said openings in the front and rear walls of the cutterhead support uncovered.

13. A shield type tunneling machine in accordance with claim 12, wherein said means for preventing depressurization of the region contiguous the face of the tunnel when one or more of the motor means is removed from the motor compartments includes a first generally annular seal extending between a forward portion of the cutterhead support and a rearwardly facing portion of the cutterhead at a location radially outboard of the gear box openings, and a second, generally annular seal, located radially inboard of said motor compartment openings and extending between a folwardly extending portion of the cutterhead support and a rearwardly extending portion of the cutterhead. v

14. The method of tunneling comprising moving a shield mounted rotary cutterbhead forwardly into material to be mined while rotating same, so as to bore a tunnel through said material, removing the mined material from the face region of the tunnel successively through the cutterhead, an opening in a transverse bulkhead portion of the shield on which the cutterhead is rotatively supported, and a material compartment extending rearwardly from a transverse bulkhead portion of the shield, maintaining fluid pressurization in said material compartment and said face region, and sealing the pressurized material compartment and face region from the pressurized remaining portion of the tunnel rearwardly of said shield, by means including said shield transverse bulkhead portion.

15. A shield type tunneling machine comprising a tunnel shield including a generally cylindrical skin having a forwardly directed cutting edge and a rearwardly extending tail section, such shield further including a transverse cutterhead support spanning the interior of said skin intermediate the ends thereof; a rotary cutterhead mounted for rotation on said cutterhead support and extending forwardly of the cutterhead support; cutting means on the front face of said cutterhead for mining the tunnel face as the cutterhead rotates; means for rotating said cutterhead; means for erecting a tunnel lining in the wake of the cutterhead and under the protection of said tail section; means for delivering compressed air to pressurize the region forwardly of the cutterhead support; means for hermetically sealing such pressurized region from the portion of the tunnel located rearwardly of said transverse cutterhead support, including a seal situated between said tail section of the shield skin and the tunnel lining; a mined material removal passageway extending through said cutterhead support; and a pressurized compartment extending rearwardly from said opening and terminating in pressure lock means, such pressure lock means permitting removal of the mined material from said compartrnent with-out depressurizing the same.

16. A shield type tunneling machine comprising a shield including a generally cylindrical skin having a forwardly directed cutting edge and a tail section; a transverse cutterhead support spanning the interior of said skin intermediate the ends thereof; a mined material removal passageway extending through said cutterhead sup port; a rotary cutterhead mounted for rotation on said cutterhead support and extending forwardly of the cutter- 'head sup-port to be at least partly enveloped by said cutting edge, said cutterhead including means for moving mined material through the cutterhead to the passageway in the cutterhead support; means for rotating said outterhead; conveyor means for moving the mined material rearwardly from said passageway in the cutterhead support, said conveyor means including a conduit communieating at its forward end with said mined material re moval passageway and extending rearwardly of said cutterhead support; pressure lock means rearwardly of and in sealed communication with said conduit; means delivering compressed air into said conduit, to pressurize the interior of said conduit and the region contiguous the face of the tunnel; means hermetically sealing the pressurized region from the rest of the tunnel, situated rearwardly of the cutterhead support; and means for moving the tunneling machine forwardly.

'17. A shield type tunneling machine comprising a tunnel shield having a generally cylindrical. skin characterized by a forwardly directed cutting edge and a rearwardly extending tail section, such shield further including a transverse support means spanning the interior to said skin intermediate the ends thereof; a passageway extending through said transverse support means; an elongated material compartment communicating at its forward end with said opening and extending rearwardly of said opening and the transverse support means, and terminating in material lock means; means delivering compressed air to pressurize the region forwardly of the transverse support means and the region interiorly of said material compartment; means hermetically sealing such pressurized regions from the unpressurized portion of the tunnel located rearwardly of said transverse support means and outside of the material compartment; and power driven conveyor means within at least a portion of said material compartment, extending essentially from the opening in the transverse support means rearwardly to the material lock means, said material lock means permitting removal of the mined material from said material compartment without depressurizing the same.

18. A shield type tunneling machine in accordance with claim 17, wherein said material compartment also includes means providing a platform extending alongside of at least a portion of the conveyor means, to serve as a walkway.

19. A shield type tunneling machine in accordance with claim 18, wherein the conveyor means is elevated a substantial distance above said walkway, and a protective partition extends alongside of said conveyor means, between it and the walkway, to prevent material from spilling over from said conveyor means onto said walkway.

20. In a shield tunneling operation involving a shield tunneling machine characterized by a generally cylindrical skin having a forwardly directed cutting edge and a rearwardly extending tail section, a transverse support portion spanning the interior of said skin intermediate the ends thereof, and a plurality of piston-cylinder thrust ram means mounted about the periphery of said support portion with the pistons thereof extendable in the rearward direction to be reactable against the tunnel lining previously erected, for in that manner advancing the tunneling machine forwardly into the material to be mined, and wherein a tunnel lining characterized by axially abutting rings of circumferentially abutting segments is erected generally in the wake of the machine, under cover of the shields skin, .a technique of continuously moving the machine forwardly while erecting the tunnel lining, comprising: shoving with some of said piston-cylinder thrust ram means against the segments of the last completely erected ring of segments, while shoving with some of the other piston-cylinder thrust ram means against the segments of the ring then being erected, while maintain-' ing at least one of said piston-cylinder thrust ram means withdrawn to allow the placement of the new segment of the lining ring then being erected in the void left by it.

21. The technique of claim 20, further including the step of rotating rotary cutterhead that is mounted for rotation on said transverse support in a position to be at least partly enveloped by the cutting edge of said cylindrical skin, while moving the machine forwardly.

22. A shield type tunneling machine comprising a shield including a generally cylindrical skin having a forwardly directed cutting edge and a tail section; transverse support means having a front wall, a rear wall, and a cellular interior construction, with said rear wall constituting a bulkhead; means delivering compressed air to pressurize the region forwardly of said transverse support means and contiguous the tunnel face; means hermetically sealing the pressurized region from the unpressurized portion of the tunnel located rearwardly of said transverse support means, said transverse support means compris-- ing a plurality of interior compartments, each of, which is isolated from the other; and a plurality of piston-cylinder actuators mounted around the periphery of said transverse support means, with the pistons thereof extending in the rearward direction to act against the tunnel lining previously erected and in that manner advancing the tunneling machine forwardly into the material to be mined, with at least one of said compartments in said transverse support means being a cylinder compartment into which the cylinder portion of at least one of the pistoncylinder actuators extends, and with such cylinder compartment being provided with means for p-ressurizing and depressurizing the same independently of the other interior compartment.

23. A shield type tunneling machine comprising a shield including a generally cylindrical skin having a forwardly directed cutting edge and a tail section; transverse sup port means having a front wall, a rear wall, and a cellular interior construction, with said rear wall constituting a bulkhead; means delivering compressed air to pressurize the region forwardly of said transverse support means and contiguous the tunnel face; means hermetically sealing the pressurized region from the unpressurized portion of the tunnel located rearwardly of said transverse support means, said transverse support means comprising a plurality of interior compartments, each of which is isolated from the others, with a cutterhead rotatably supported on said transverse support means, said outterhead extending forwardly of said transverse support means so as to be at least partially enveloped by the shield skin, and a plurality of thrust rams mounted around the periphery of said support means, each such thrust ram including as a portion thereof means extending in the rearward direction to react against the tunnel lining previously erected and in that manner advancing the tunneling machine forwardly into the material to be mined, with at least one of the compartments in said supporting means housing a portion of at least one of said thrust rams, said compartment including conduit means extending between it and a continuously pressurized region of the supporting means, with normally open valve means situated in said conduit, and said cornpartment further including a norm-ally closed dump valve positioned to exhaust into the main portion of the tunnel situated rearwardly of the support means when such valve is opened.

24. A shield type tunneling machine comprising a shield including a generally cylindrical skin having a forwardly directing cutting edge and a tail section; a transverse cutterhead support spanning the interior of said skin intermediate the ends thereof; a mined material removal passageway extending through said cutterhead sup-port; rotary cutterhead means mounted for rotation on, and extending forwardly of the cutterhead support; means for rotating said cutterhead means; means for moving mined material into the passageway in the cutterhead support; means for moving the mined material rearwardly from said passageway in the cutterhead support, said means including a conduit communicating at its forward end with said mined material removal passageway and extending rearwardly of said cutterhead support; pressure lock means rearwardly of and in sealed communication with said conduit; means delivering compressed air to pressurize the interior of said conduit and the region contiguous the face of the tunnel; means hermetically sealing the pressurized region from the rest of the tunnel, situated rearwardly of the cutterhead support; and means for moving the tunneling machine forwardly.

References Cited by the Examiner UNITED STATES PATENTS 438,509 10/1890 Vering 6184 794,633 7/1905 Moir 61-85 1,277,107 8/1918 ORourke 6185 1,292,159 1/ 1919 Trumpour 6185 1,338,237 4/1920 Mack 6184 1,429,647 9/ 1922 Sheen 6185 1,720,195 7/1929 App 88 X 3,061,282 10/1962 Robbins 262-7 3,075,591 1/ 1963 Pirrie et a1. 175319 FOREIGN PATENTS 348,743 2/ 1905 France.

CHARLES E. OCONNELL, Primary Examiner.

JACOB SHAPIRO, Examiner.

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Classifications
U.S. Classification405/144, 299/56, 299/31, 405/146, 405/147, 277/583
International ClassificationE21D9/12, E21D19/00, E21D9/08, E21D9/06, E21D9/087
Cooperative ClassificationE21D9/081, E21D9/12, E21D19/00, E21D9/0621
European ClassificationE21D9/08B, E21D9/12, E21D9/06D, E21D19/00