SHIELD ADVANCING EXCAVATOR

Abstract: A shield advancing excavator (1) for excavating tunnels comprises a cylindrical shield body (2), a deck (20) fixed to and within said body (2) and extending rearwardly, an erector (18) mounted axially movably on said deck (20) and adapted to erect a segmental ring inside said body from arcuate segments (23), a holder (19) fixed to said erector (18) and engageable with and disengageable from the inner wall (17) of a ring erected inside said body (2) to fix said erector axially relatively to said erected ring when so engaged, a plurality of axially-extending shield jacks (15) mounted within said body adjacent the periphery of said body in axial alignment with the erected ring segments, each of said jacks having a spreader (14) rearwardly extendible by the respective jack to engage with the last-erected ring segment in alignment with that jack to provide a reaction force to advance said body, whereby said excavator (1) can advance while a ring is being erected, the erector being held axially stationary by the holder during the erection. The shield jacks are arranged in groups around the shield body whereby they are retractible group by group to enable a ring to be constructed stepwise while jacks that are unretracted during each constructional step remain effective to advance the shield body.

Description: The present invention relates to a shield advancing excavator, which is adapted to erect segment rings from arcuate segments inside an excavated tunnel. A conventional excavator of this type includes an erector fixed to a shield body adjacent the rear thereof. During, excavation, the erector must discontinue erection of a segment ring to advance with the body. The erector in the stand-by state can start erection after the body stops when the excavator has excavated a tunnel for one segment ring. Because the body advances and the erector erects a segment ring alternately, continuous excavation is not possible and the erection is not smooth. To solve these problems, another conventional excavator has a shield body divided into a front barrel with a cutter disc, and a rear barrel with an erector. The barrels are arranged telescopically. While the front barrel performs excavation, the erector on the immobily standing rear barrel performs erection. However, when the erector finishes the erection, a certain period is required to draw the rear barrel up to the front barrel. During this period, the shield body must stop advancing, thus preventing continuous excavation. It is a general object of the present invention to provide a shield advancing excavator, which enables the shield body to continue excavation while the erector con­ tinues erection. An excavator according to the invention comprises: a cylindrical shield body; a deck fixed to and within said body and extending rearwardly; an erector mounted axially movably on said deck and adapted to erect a segmental ring inside said body from arcuate segments; a holder fixed to said erector and engageable with and disengageable from the inner wall of a ring erected inside said body to fix said erector axially relatively to said erected ring when so engaged; a plurality of axially-extending shield jacks mounted within said body adjacent the periphery of said body in axial alignment with the erected ring segments, each of said jacks having a spreader rearwardly ex­ tendible by the respective jack to engage with the last erected ring segment in alignment with that jack to provide a reaction force to advance said body; whereby said excavator can advance while a ring is being erected, the erector being held axially stationary by the holder during the erection. A preferred embodiment of the invention will be described below with reference to the accompanying drawings, wherein: Fig.1 is a side view in longitudinal cross section of an excavator according to the invention; Fig. 2 is a partial view in cross section along line II-II of Fig.1; Fig. 3 is a schematic view showing grouping of shield jacks and a sequence of erecting a segment ring according to the invention; Fig.4 is a chart of the time schedule of erecting a segment ring according to the invention; Fig. 5 is a partial view in cross section along line V-V of Fig. 1. With reference to Figs. 1, 2 and 5, an excavator 1 includes a cylindrical shield body 2, which surrounds a circular bulkhead 10 fixed thereto adjacent the front end thereof. The body 2 forms an operating room 3 in the rear of the bulkhead 10. The bulkhead 10 supports hydraulic motors 4 thereon which are located in the room 3. The motors 4 have gears 5 on their output shafts in engagement with a ring gear 6, which is fixed to a cutter disc 7 for excavating a working face 45 at the forward end of the body 2. The disc 7 is journalled by a slewing bearing 8 coaxially on the bulkhead 10. The disc 7 forms a cutter chamber 9 in front of the bulkhead 10. The chamber 9 is insulated from the room 3 by seals 11 on the bulkhead 10. From the cutter chamber 9 through the bulkhead 10 extend a belt conveyor 12 for discharging muck soil and pipes 13 for discharging mud slurry, with seals (not shown) provided to seal the chamber 9. The pipes 13 are connected to pipes (not shown) extending rearwardly. The shield body 2 has a ring girder 21 therewithin adjacent the operating room 3. The girder 21 supports a plurality (24 in this example) of axially extending hydraulic shield jacks 15 fixed thereto adjacent the inner wall of the shield body 2. Each jack 15 has a piston rod extending rearwardly. Fixed to the rear end of the rod is a spreader 14. The jacks 15 are axially displaced in five steps as shown by chain line M in Fig. 1. As shown in Fig. 3, the jacks 15 are grouped in eight arcuate sections I-VIII, forming a ring inside the shield body 2, and each containing three of the jacks. The bottom section I is axially the most forward step. Three pairs, each on the same level, of the sections II-III, IV-V and VI-VII are axially the same steps, respectively. The top section VIII is the most rearward step. This arrangement is such that arcuate segments 23, each corresponding to one of the sections I-VIII, can be assembled stepwise inside the shield body 2 according to the sequence of the sections I-VIII in Fig. 3 to form a segment ring 17A, which is part of a tunnel wall 17. The jacks 15 have a stroke length substantially longer than the segments 23. Specifically, the stroke is substantially longer than (1 + ) x W, where N is the number of the sections I-VIII, and W is the axial width of the segments 23. If the jacks 15 were not displaced, longer jacks would be necessary for the segments 23 to be assembled later in erecting one segment ring 17A, and at the final step, the jacks would have to have an approximately double length of stroke. Thus, the displaced arrangement allows the jacks 15 to have an equal and short stroke length. The shield body 2 also forms a central or main space 24 therewithin in the rear of the operating room 3. Through the space 24 extends a deck 20, which may have a conventional construction, including an axial platform, for supporting the operators fastening segments 23 at a higher position of a segment ring 17B being erected. The deck 20 has a front end 20a fixed to a pair of pillars 22, which are fixed to the ring girder 21. The deck 20 extends rearwardly. From the rear end of the deck extend telescopic legs, which carry wheels 25 for auxiliarily supporting the deck 20. The deck 20 has a pair of axial rails 20A fixed to its platform at both edges. The rails 20A slidably support an erector holder or fixer 19, which is fixed to an erector 18 located forwardly of the holder. Fixed to the deck 20 are a pair of axially extending hydraulic cylinders 26 on its platform adjacent its front. The piston rod 26A of each cylinder is connected to a chain 27, which extends around a pair of sprockets 28A-28B journalled on each side wall 20b of the deck 20 and spaced axially of the shield body 2. The chain 27 is connected to the erector holder 19, so that the erector 18 moves axially along the deck 20 by the action of the cylinders 26. If the cylinders 26 are released, the erector 18 and holder 19 can remain in the current location without following any forward movement of the shield body 2 during erection of a segment ring. This prevents the forward movement of the body 2 and deck 20 from interrupting the erection. The erector holder 19 includes a pair of upper and lower arcuate grippers 19A for compressive engagement with the inner side of the tunnel wall 17, and four pillars 32 interconnecting the ends of the grippers 19A at both sides and at the front and rear. Each pillar 32 has a pair of upper and lower hydraulic cylinders 31 and 30, which are extensible to compress the grippers 19A against the wall 17. The erector holder 19 also includes a hydraulic motor 39 provided adjacent the bottom and having an output shaft with a gear 40. This gear engages a ring gear 41 journalled by a slewing bearing 42 on the holder 19 coaxially with the shield body 2. The erector 18 includes a segment hoist 33 and a drum 34, which is fixed to the ring gear 41 to rotate the hoist on the axis of the shield body 2. The hoist 33 has a girder 33A, to which the piston rods 35a of axial hydraulic jacks 35 are fixed. The cylinder 35A of each jack carries a chuck 36 for hoisting a segment 23 and axially moving it. The hoist 33 has a pair of hydraulic cylinders 38, which are perpendicular to the axis of the body 2, for radially moving the segment 23, so as to automatically erect a segment ring 17B. Through the lower gripper 19A extends a portable roller conveyor 43 to convey segments 23 from the rear of the tunnel to the erection place. In operation, the erector 18 can continue assembling segments 23 to form a tunnel wall 17, without interrupting the forward movement of the shield body 2, in the following manner: In Fig. 1, the shield body 2 is forwardly moving to erect a segment ring 17B in front of a previously erected segment ring 17A, while the erector 18 is erecting the ring 17B, with the erector holder 19 engaging the tunnel wall 17. Specifically, when the erector 18 has completed erection of the segment ring 17A, the cylinders 30-31 of the holder 19 are retracted to release the grippers 19A from the tunnel wall 17. The cylinders 26 on the deck 20 are then retracted to move the chains 27 counterclockwise as seen in Fig. 1. This forwardly slides the holder 19 and erector 18 along the deck 20. When the cylinders 26 have retracted, the cylinders 30-31 are extended so that the grippers 19A grip the wall 17 again to fix the holder 19 and erector 18 in place. Shortly before the fixation, the cylinders 26 are released so that the shield body 2 and deck 20 can keep forwardly moving. The hydraulic motors 4 are energized to rotate the cutter disc 7. A predetermined number of the shield jacks 15 are extended with the spreaders 14 compressing the front ends 17a and 17b of the segment rings 17A and 17B, respectively, to obtain a reaction force for the forward movement of the shield body 2 and deck 20. The segments 23 are assembled upwardly and alternately on both sides in the sequence of the arcuate sections I-VIII of Fig.3. In each stage of the sequence, the three jacks 15 of the appropriate section retract for erection. The other jacks 15 act to assist the operation of the jacks in each stage. In the last section VIII, the top key segments are assembled. This operation will be explained specifically with reference to Figs. 3-4. Fig. 4 shows the jacks 15 in three states, which are strong compression, weak compression and releasing or retraction. In the first stage of the erecting sequence, the jacks 15 of the section I are fully retracted to forwardly move the spreaders 14 a distance slightly longer than the segments 23 (Fig. 1), and the bottom segments 23 are then assembled axially in end-to-end relation with those of the previously erected segment ring 17A. The jacks 15 of section I are subsequently extended to weakly compress the segments 23 of the ring 17B being newly erected, so that the spreaders 14 contact the front end 17b of the ring 17B. This facilitates aligning and bolting the adjacent segments 23, and eliminates a time which the jacks 15 of the section I would take until they can start obtaining reaction forces for excavation against the segments 23 when the segments are assembled in the fifth stage at the section V. The time T1 required for the assembly in the section I is scheduled to be within 1/8 of the total time required for the shield body 2 to proceed by the length of one ring 17B. Shortly before the assembly in the section I ends, the jacks 15 of the section II retract. Subsequently, the erector 18 assembles new segments 23, which have been received from the conveyor 43, in the section II. After positioning the segments 23 in place, the operators bolt the adjacent segments together and the segments to the erected ring 17A. This operation is repeated also for the sections III-­ VIII. Incorporation of the key segments 23 in the final section VIII completes the erection of the ring 17B. Throughout the erection, at least twelve of the jacks 15 are strongly compressing the front ends of the rings 17A, 17B so as to keep the shield body 2 advancing for excavation. When the ring 17B has been erected, the erector 18 and holder 19 advance by the width of the ring to erect a new ring. With reference to Fig.4, the total period to erect one segment ring is the sum of the times T1-T8 in the assembly stages at the sections I-VIII and the transit time TR for the erector 18 to advance for the next erection. As stated above, this period is scheduled to eliminate the time losses. This arrangement accomplishes approximately twice the conventional excavating performance.

Claims: 1. A shield advancing excavator comprising: a cylindrical shield body; a deck fixed to and within said body and extending rearwardly; an erector mounted axially movably on said deck and adapted to erect a segmental ring inside said body from arcuate segments; a holder fixed to said erector and engageable with and disengageable from the inner wall of a ring erected inside said body to fix said erector axially relatively to said erected ring when so engaged; a plurality of axially-extending shield jacks mounted within said body adjacent the periphery of said body in axial alignment with the erected ring segments, each of said jacks having a spreader rearwardly extendible by the respective jack to engage with the last erected ring segment in alignment with that jack to provide a reaction force to advance said body; whereby said excavator can advance while a ring is being erected, the erector being held axially stationary by the holder during the erection. 2. An excavator according to Claim 1, wherein the shield jacks are arranged in groups around the shield body whereby they are retractible group by group to enable a ring to be constructed stepwise while jacks that are unretracted during each constructional step remain effective to advance the shield body. 3. An excavator according to Claim 2, wherein the groups of shield jacks contain equal numbers of jacks, one group being at the bottom of the shield body, one at the top and the others being arranged in one or more pairs, the two groups in each pair being disposed symmetrically at opposite sides of the shield body. 4. An excavator according to any one of Claims 1 to 3, wherein the number of shield jacks is equal to the number of segments in a ring, one jack being in axial alignment with each segment. 5. An excavator according to any one of Claims 1 to 4, comprising drive means on the platform for advancing the erector relatively to the platform when the holder is disengaged. 6. An excavator according to any one of Claims 1 to 5, wherein the erector comprises powered means for hoisting and lifting fresh ring segments into position during con­ struction of a ring, which powered means are rotatable about the axis of the shield body. 7. An excavator according to any one of Claims 1 to 6, wherein the holder comprises a pair of symmetrically-­ opposed arcuate grippers that are movable radially outward and inward with respect to the axis of the shield body by fluid-pressure-operated jacks.

Inventors: YOSHINO, OSAMU
Applicants: KAWASAKI JUKOGYO KABUSHIKI KAISHA
Application year: 1986
Main classification: E21D9
IPC codes: B01F13, E21D11, E21D9