Excavator and methods of use thereof

Abstract: An excavator for constructing an underground continuous wall includes a travelling trolley (4) movable on rails (2) and having a sprocket (8) in mesh with a rack (7) extending parallel to the rails and a hydraulic motor (9) for driving the sprocket. The trolley further includes an upper frame (10) arranged thereon and having a tiltable frame (12) which is tiltable relative to the upper frame and a saddle (19) provided on the tiltable frame to be slidable on the tiltable frame in directions substantially perpendicular to the rails (2). An extensible guide post (24) is provided to be upwardly and downwardly movable relative to the tiltable frame (12). An endless chain (32) extends around a chain driving wheel (23) provided on the saddle (19) and a chain sprocket (30) provided at the lower end of the guide post, and a number of cutter bits (33) and a number of agitator bars (34) are alternately arranged on the endless chain to form an endless chain cutter (C). A chain driving device (22) is provided for driving the endless chain (32).

Description: This invention relates to an excavator for excavating ground, for example, to construct an underground continuous wall. In constructing such an underground continuous wall according to a prior art technique, first a hole of an elliptical section having a 2 to 3 m major axis is dug in the ground to a predetermined depth by a powerful bucket, or a hole is dug to a predetermined depth by two or three series of auger drills. After the hole is formed it is sealed with a bentonite solution to prevent further penetration of slurry, a reinforcing bar cage is placed in the hole and a ready mixed-concrete is then poured into the hole to form a foundation column. Such a method is repeated to form an underground continuous wall. With the underground continuous wall construction method of the prior art described above, the processes are complicated and hence take much time to complete the continuous wall. Moreover, slurry or bentonite solution layers at joints between successive columns interrupt the formation of the continuous wall so that after completion of the wall ground water tends to leak into the inside of the continuous walls through the joints. It is therefore very difficult to provide an underground continuous wall simultaneously having two functions as a foundation wall and a diaphragm wall. EP-A-0 249 231 discloses a trenching apparatus for excavating deep trenches in which inground concrete retaining or foundation walls may be formed. The trenching apparatus has a crawler base on which a carrier assembly is pivotally supported by pivots, whereby it may be tilted by rams to maintain the platform horizontal. Automatic control means are provided for this purpose. The carrier assembly has a pair of rails along which a carriage may move. The carriage supports a sleeve through which a trenching arm may be lowered to excavate a trench section as the carriage is driven along the rails. GB-A-1 099 699 discloses a machine for constructing a water-impermeable sheet in the ground by progressively loosening the ground while a liquid or semi-liquid sealing material is injected into the loosened ground to mix therewith so as to form hardenable material which hardens into the water-impermeable sheet. The machine comprises a frame movable over the ground, a blade which is mounted for movement with respect to the frame and a tooth which is an endless chain provided with teeth carried on the blade. Ducting is adapted to supply a liquid or semi-liquid sealing material to the ground which has just been loosened by the tool. According to one aspect of the present invention there is provided an excavator comprising a trolley movable on rails, an upper frame mounted on the trolley and provided with a tiltable frame which is tiltable about its lower portion relative to the upper frame and the trolley about an axis generally parallel to the longitudinal extent of the rails on which the trolley is movable, a saddle provided on the tiltable frame to be slidable thereon in directions substantially perpendicular to the longitudinal extent of the rails and having a chain driving wheel provided thereon to be positioned, in use, offset laterally with respect to the longitudinal extent of the rails, a guide post positioned below the chain driving wheel to be upwardly and downwardly movable relative to the tiltable frame and having a chain sprocket rotatably connected to the lower end thereof, an endless chain extending around the chain sprocket and the chain driving wheel on the saddle, a plurality of cutter bits and agitator bars arranged on the endless chain to form an endless chain cutter, and chain driving means for driving the endless chain. According to a further aspect of the present invention there is provided a method of using the excavator of the first aspect of the present invention, the method comprising steps of digging a hole in the ground to a predetermined depth by means of a drilling device, inserting the endless chain cutter of the excavator into the hole, and excavating the ground in a predetermined direction by means of the endless chain cutter, whilst jetting a hardening liquid into the excavated hole, to thereby mix the hardening liquid with the earth and/or sand in the excavated hole to form a soil cement wall. According to a yet further aspect of the present invention there is provided a method of using the excavator of the first aspect of the present invention, the method comprising steps of digging a hole in the ground to a predetermined depth by means of a drilling device, inserting the endless chain cutter of the excavator into the hole, and excavating the ground in a predetermined direction by means of the endless chain cutter, whilst inserting into the excavated hole an agitator substantially similar in construction to the endless chain cutter and having a hardening liquid injection pipe to jet a hardening liquid into the excavated hole, to thereby mix the hardening liquid with the earth and/or sand in the excavated hole to form a soil cement wall. According to an even further aspect of the present invention there is provided a method of using the excavator of the first aspect of the present invention, the method comprising steps of digging a hole in the ground to a predetermined depth by means of a drilling device, inserting the endless chain cutter of the excavator into the hole, and excavating the ground in a predetermined direction by means of the endless chain cutter and removing the excavated earth and sand, whilst inserting an injection pipe into the excavated hole behind the endless chain cutter to jet a hardening liquid mixed with the removed earth and/or sand into the excavated hole, to thereby fill the excavated hole with soil cement or mortar. The hereinafter described and illustrated embodiment of excavator is capable of constructing an underground continuous wall in a simple process in a short time. The resultant wall may be substantially smoothly continuous and can have twin functions as a foundation wall and as a diaphragm wall. The hereinafter described methods of construction enable the fabrication of an underground continuous wall rapidly and easily, to result in a wall without joints and without risk of leakage of ground water. An embodiment of excavator in accordance with the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a sideview of an embodiment of an excavator in accordance with the present invention; Fig. 2 is a front view of the excavator shown in Fig. 1; Fig. 3 is a plan view of the excavator shown in Fig. 1; Figs. 4a, 4b and 4c are front, plan and side views of one example of cutter bits used in the endless chain cutter of the excavator according to the invention, respectively; Figs. 5a, 5b and 5c are front, plan and side views of one example of agitator bars used in the endless chain cutter of the excavator according to the invention, respectively; Figs. 6a, 6b, 6c, 6d and 6e are views illustrating the processes of the first construction method according to the invention; Figs. 7a, 7b, 7c and 7d are views illustrating the processes of the second construction method according to the invention; and Figs. 8a, 8b, 8c, 8d and 8e are views illustrating the processes of the third construction method according to the invention. Referring to the drawings, reference numeral 1 denotes a ground or foundation to be constructed therein with a continuous wall. In the illustrated embodiment, a lower frame 3 is arranged on the ground 1 along an underground continuous walls to be formed, and two rails 2 are arranged on the lower frame 3. A traveling trolley 4 is movably located on the rails 2. The traveling trolley 4 has wheels 5 rolling on the rails 2 and rollers 6 to be fitted in the lower frame 3 for preventing the trolley 4 from falling down. A pin rack 7 is provided on one of the rails 2 in parallel therewith (Figs. 2 and 3), while a sprocket 8 is provided on the trolley 4 so as to be in mesh with the pin rack 7 and driven by a hydraulic motor 9. An upper frame 10 (Fig. 2) is mounted on the trolley 4. The upper frame 10 is provided on its one side (its left side viewed in Fig. 2) with a tiltable frame 12 whose lower end is pivotally connected to the trolley 4 so as to permit the upper portion of the frame 12 to be tilted. In order to tilt the tiltable frame 12, the upper frame 10 is provided thereon with a hydraulic motor 13, a reduction device 14 connected thereto, a screw shaft 15 rotatable relative to the upper frame 10 and driven by the hydraulic motor 13 through the reduction device 14, a nut 16 adapted to be threadedly engaged on the screw shaft 15, and a link 17 connecting the nut 16 and the upper portion 12a of the tiltable frame 12. A horizontal base 12b is provided on the upper portion 12a of the tiltable frame 12. Two rails 18 (Fig. 3) is provided on the horizontal base 12b in the direction perpendicular to the rails 2. A saddle 19 is slidably arranged on the rails 18 and adapted to be driven by a hydraulic cylinder 20 (Fig. 3) and guided by a limit guide 21 (Fig. 2). On the saddle 19 is provided a hydraulic motor 22 having an output shaft 22a to which is fixed a driving wheel 23 for driving an endless chain (later described). A guide post 24 is extensible by connecting extension post members to the post 24 and is provided below the driving wheel 23 vertically movably with the aid of the wire 26 of a hydraulic winch 25 provided on the tiltable frame 12. A guide pulley 27 for the wire 26 of the winch 25 is provided on the tiltable frame 12. The guide post 24 is fixed to the tiltable frame 12 by means of a post fixing block 28. An injection pipe 29 for pouring mortar extends from the upper frame 10 into the guide post 24 and has branched lower ends 29a opening at the lower end of the guide post 24. A chain sprocket 30 is rotatably supported on the lower end of the guide post 24 by means of a pin 31. An endless chain 32 extends the chain sprocket 30 and the driving wheel 23 on the saddle 19. A number of cutter bits 33 and a number of agitator bars 34 are alternately arranged on the endless chain 32 to form an endless chain cutter C. A plurality of cutter bits 33 are fixed to a base plate 33a which is fixed to each of links of the endless chain 32. One example of arrangements of the cutter bits 33 is shown in Figs. 4a, 4b and 4c. Plural cutter bits 33 are fixed to a base plate 33a which is fixed to each of links of the endless chain 32. A plurality of agitator bars 34 are fixed to a base plate 34a which is fixed to each of links of the endless chain 32. One example of arrangements of the agitator bars 34 is shown in Figs. 5a, 5b and 5c. Plural agitator bars 34 are fixed to a base plate 34a which is fixed to each of links of the endless chain 32. The traveling trolley 4 includes an operator's cabin 35, a side frame 36 provided adjacent to the upper frame 10, a slide deck 37 slidably movable on the side frame 36, a collapsible deck 38 on the slide deck 37, a ladder 39 attached to the side frame 36 for going up to its top, a hydraulic unit 40 arranged in the side frame 36, a control unit 41, a power cable 43 wound around a reel 42, and handrails 44 and 45. In constructing an underground continuous wall by the use of the excavator constructed described above, first a vertical hole 47 having a predetermined depth is dug in the ground at a position where the underground continuous wall is to be formed by means of earth drills 46 or the like as shown in Figs. 6a-6e, 7a-7d and 8a-8e. The endless chain cutter C having a desired length is then assembled and placed in the vertical hole 47. Thereafter, the chain 32 of the endless chain cutter C is driven by means of the hydraulic motor 22 in directions shown by arrows A and B in Fig. 1, while the traveling trolley 4 is advanced in the direction shown by an arrow D in Fig. 1 by driving the sprocket 8 in mesh with the pin rack 7 by means of the hydraulic motor 9 to form a continuous groove in the ground 1. In assembling the endless chain cutter C, after the saddle 19 has been moved in the direction shown by an arrow E in Fig. 2, the guide post 24 joined with some spare members to have a desired length is hung in front of the tiltable frame 12. The hung guide post 24 is then inserted into the vertical hole 47. After the height of the guide post 24 has been adjusted by means of the wire 26 and the hydraulic winch 25, the guide post 24 is fixed through the fixing block 28 to the tiltable frame 12. When the hydraulic motor 13 having the reduction device 14 is actuated to rotate the screw shaft 15 threadedly engaged with the nut 16, the nut and the link 17 connected thereto are moved to tilt the tiltable frame 12 about the pin 11, thereby adjusting the inclination of the guide post 24. Consequently, the guide post 24 can be vertically maintained exactly. After the guide post 24 has been fixed in position in the manner described above, the saddle 19 is moved by means of the hydraulic cylinder 20 in the direction shown by an arrow F in Fig. 2 to arrange the driving wheel 23 directly above the guide post 24. At this time, the endless chain 32 has been already supported by the guide post 24 and extending around the chain sprocket 30 provided at the lower end of the guide post 24. The endless chain 32 also extends around the driving wheel 23 immediately above the guide post 24 to complete the endless chain cutter C. Figs. 6a to 6e illustrate a first construction method according to the invention. A figure at the bottom of each of Figs. 6a to 6e schematically shows a cross-section of the ground. First, a hole 47 is digged in the ground 1 to a predetermined depth by means of a boring device 46 such as an earth drill as shown in Fig. 6a. The endless chain cutter C of the excavator according to the invention is then inserted into the hole 47. Thereafter the trolley is driven in the predetermined direction shown by an arrow G in Fig. 6b to excavate the ground 1, while a hardening liquid such as cement milk is jetted into the excavated hole through the injection pipe 29 provided in the guide post 24 of the endless chain cutter C as shown in Fig. 6c. As a result, the hardening liquid is mixed with earth and sand in the excavated hole to form a soil cement wall 48 as shown in Figs. 6c, 6d and 6e. Reference numeral 49 illustrates H-beams inserted in the soil cement wall 48 with suitable intervals by hanging the H-beams 49 before the soil cement wall 48 have hardened. Figs. 7a to 7d illustrate a second construction method according to the invention. First, an agitator K is prepared, which is substantially similar in construction to the endless chain cutter C and includes an injection pipe 29 provided in a guide post 24 for pouring a hardening liquid. A hole 47 is digged in the ground 1 to a predetermined depth by means of a boring device 46 such as an earth drill as shown in Fig. 7a. The endless chain cutter C of the excavator according to the invention is then inserted into the hole 47. Thereafter the trolley is driven in the predetermined direction shown by an arrow H in Fig. 7b to excavate the ground 1, while the agitator K is inserted behind the endless chain cutter C and a hardening liquid is jetted through the injection pipe 29 of the agitator K as shown in Fig. 7c to mix the hardening liquid with earth and sand in the excavated hole to form a soil cement wall 48 as shown in Fig. 7d. Reference numeral 49 illustrates H-beams inserted in the soil cement wall 48 with suitable intervals by hanging the H-beams 49 before the soil cement wall 48 have hardened. Figs. 8a to 8e illustrate a third construction method according to the invention. First, a hole 47 is dug in the ground 1 to a predetermined depth by means of a boring device 46 such as an earth drill as shown in Fig. 8a. The endless chain cutter C of the excavator according to the invention is then inserted into the hole 47 as shown in Fig. 8b. Thereafter, the trolley is driven in the predetermined direction shown by an arrow I in Fig. 8b to excavate the ground 1 and remove the earth and sand as shown by an arrow J in Fig. 8b, while an injection pipe 50 is inserted behind the endless chain cutter C and a hardening liquid mixed with the removed earth and sand is poured through the injection pipe 50 into the excavated hole as shown by L in Fig. 8c. As a result, the excavated hole is filled with soil cement or soil mortar to form a wall 48 as shown in Figs. 8d and 8e. Reference numeral 49 illustrates H-beams inserted in the soil cement wall 48 with suitable intervals by hanging the H-beams 49 before the soil cement wall 48 have hardened. As can be seen from the above explanation, with the traveling trolley provided with the driving sprocket in mesh with the rack provided on one of the rails arranged on the ground, the trolley can be powerfully and securely driven without slipping relative to the rails. Moreover, the inclination of the endless chain cutter of the excavator according to the invention can be exactly adjustable relative to the ground and length of the endless chain cutter can be easily adjusted by connecting extension post members to the guide post. By the use of the excavator according to the invention, an underground continuous wall can be constructed in high accuracy and with very high efficiency. Moreover, the excavator according to the invention is high in constructional stability and hence there is no risk of falling down. Furthermore, according to the construction methods of the invention, it is possible to construct a foundation wall in the ground which is able to be used as a diaphragm wall also.

Claims: An excavator comprising a trolley (4) movable on rails, an upper frame (10) mounted on the trolley and provided with a tiltable frame (12) which is tiltable about its lower portion relative to the upper frame and the trolley about an axis generally parallel to the longitudinal extent of the rails on which the trolley is movable, a saddle (19) provided on the tiltable frame to be slidable thereon in directions substantially perpendicular to the longitudinal extent of the rails (2) and having a chain driving wheel (23) provided thereon to be positioned, in use, offset laterally with respect to the longitudinal extent of the rails, a guide post (24) positioned below the chain driving wheel to be upwardly and downwardly movable relative to the tiltable frame and having a chain sprocket (30) rotatably connected to the lower end thereof, an endless chain (32) extending around the chain sprocket and the chain driving wheel on the saddle, a plurality of cutter bits (33) and agitator bars (34) arranged on the endless chain to form an endless chain cutter (C), and chain driving means (22) for driving the endless chain. An excavator as claimed in claim 1, wherein the trolley (4) has at least one sprocket (8) arranged to mesh with a rack (7) associated with one of the rails and sprocket driving means (9) for driving the sprocket. An excavator as claimed in claim 1 or claim 2, wherein the upper frame (10) is provided with a hydraulic motor (13) having a reduction device (14), a screw shaft (15) rotatively driven by the hydraulic motor, a nut (16) threadedly engaged on the screw shaft, and a link (17) connected to the nut and the upper portion of the tiltable frame (12). An excavator as claimed in any one of the preceding claims, wherein the tiltable frame (12) is provided thereon with a horizontal base (12b) on which rails (18) are provided for slidable movement thereon of the saddle (19), and a hydraulic cylinder (20) is provided for driving the saddle. An excavator as claimed in any one of the preceding claims, wherein the tiltable frame (12) is provided with a hydraulic winch (25) and a guide pulley (27) for the wire (26) of the winch. An excavator as claimed in any one of the preceding claims, wherein the endless chain cutter (C) comprises an injection pipe (29) extending from the upper frame (10) into the guide post (24) and having branched lower ends (29a) opening at the lower end of the guide post. A method of using an excavator of the construction claimed in any one of the preceding claims, wherein the method comprises steps of digging a hole in the ground to a predetermined depth by means of a drilling device, inserting the endless chain cutter (C) of the excavator into the hole, and excavating the ground in a predetermined direction by means of the endless chain cutter, whilst jetting a hardening liquid into the excavated hole, to thereby mix the hardening liquid with the earth and/or sand in the excavated hole to form a soil cement wall. A method of using an excavator of the construction claimed in any one of claims 1 to 6, wherein the method comprises steps of digging a hole in the ground to a predetermined depth by means of a drilling device, inserting the endless chain cutter (c) of the excavator into the hole, and excavating the ground in a predetermined direction by means of the endless chain cutter, whilst inserting into the excavated hole an agitator substantially similar in construction to the endless chain cutter and having a hardening liquid injection pipe to jet a hardening liquid into the excavated hole, to thereby mix the hardening liquid with the earth and/or sand in the excavated hole to form a soil cement wall. A method of using an excavator of the construction claimed in any one of claims 1 to 6, wherein the method comprises steps of digging a hole in the ground to a predetermined depth by means of a drilling device, inserting the endless chain cutter (C) of the excavator into the hole, and excavating the ground in a predetermined direction by means of the endless chain cutter and removing the excavated earth and sand, whilst inserting an injection pipe into the excavated hole behind the endless chain cutter to jet a hardening liquid mixed with the removed earth and/or sand into the excavated hole, to thereby fill the excavated hole with soil cement or mortar. A method as claimed in any one of the claims 7 to 9, wherein, before the hardening liquid jetted into the excavated hole hardens, reinforcing members are inserted into the liquid in the excavated hole.

Inventors: KITANAKA KATSUMI, KITANAKA TAKEHIKO, KITANAKA, KATSUMI, KITANAKA, TAKEHIKO
Applicants: KOBE STEEL LTD, TOMEN KENKI CORP, KOBE STEEL, LTD, TOMEN KENKI CORPORATION
Application year: 1992
Main classification: E02F3
IPC codes: E02D5, E02F5, E02F9, E02F3, E02D17