APPARATUS FOR IMPROVING GROUND

Abstract: Improving ground by inserting into the ground a guide rod (1) equipped with a bit (2) at its forward end and an arm cutter (3) transversely extending from the lower portion of the guide rod (1) by guiding the rod by the rotation of the bit (2) and the rotation of the arm cutter (3) about its own axis, and gradually withdrawing the guide rod (1) from the ground when the rod has reached a predetermined depth while revolving the arm cutter (3) about the axis of the rod (1) in addition to its rotation to agitate the portion of the ground covered by the revolution about the axis of the guide rod (1) and while injecting a liquid agent into the agitated portion of the ground from discharge outlets (8) (8′) in the arm cutter (3) and the bit (1).

Description: APPARATUS FOR IMPROVING GROUND The present invention relates to an apparatus for improving the ground, and particularly to an apparatus for improving the ground which apparatus is useful in hardening the ground by injecting cement milk, cementbentonite mixture or like ground improving liquid agent into soft ground. Ground improving apparatus are known which comprise a guide rod havng a bit at its forward end, and an arm cutter attached to the guide rod, retractable into or extendable from the rod and rotatable about its own axis by being controlled on the ground. When the guide rod is inserted into the ground to be improved to a predetermined depth by being guided by the rotation of the bit, the arm cutter retracted in its stowed position during the insertion is turned through 90" to a position at right angles to the rod while being rotated. Subsequently while slowly lifting the guide rod with the arm cutter held in rotation to agitate the neighboring soil, a ground improving liquid agent is injected into the agitated ground portion from openings in the arm cutter and the bit to improve the ground. Since the known apparatus is adapted to agitate the ground and, at the same time, fill the agitated portion of the ground with the injected liquid agent to improve the ground, the apparatus has the advantage of being capable of effectively improving the ground with stability without being influenced by the quality of the soil. However, such known apparatus is adapted to merely improve the portion of ground through which the arm cutter passes in rotation, so that the width of ground improved at a time approximately corresponds to the diameter of cross section of the arm cutter and is not very large. Accordingly if the apparatus is used for improving the ground over a large width or for improving soft ground which must be treated over a wide area, the apparatus must be operated repeatedly many times to result in a low work efficiency. Thus the apparatus is substantially unusable for such purposes. Further because the arm cutter is adapted to be stowed in or extended from the guide rod, the apparatus of the type described is complex in construction and is also complicated to operate owing to the necessity of turning the arm cutter through 90" in the ground from its stowed position to the extended position at right angles to the rod. An object of the present invention is to provide a ground improving apparatus of the type described which achieves such a high work efficiency that the ground can be improved at a time over a circular area having a radius corresponding to the length of an arm cutter. Another object of the invention is to provide a ground improving apparatus of the type described which is simple in construction and easy to operate for the improvement of the ground. The present invention provides an apparatus for improving ground comprising a guide rod to be inserted into the ground to-a predetermined depth, a bit attached to the forward end of the guide rod and rotatable when the rod is inserted into the ground to guide the rod into the ground, the bit-having a discharge outlet for injecting a ground improving liquid agent into an agitated portion of the ground while the rod is withdrawn from the ground with the bit held in continued rotation, and at least one arm cutter'having a discharge outlet and attached to a lower portion of the guide rod for agitating the ground and simultaneously injecting the ground improving agent into the agitated ground portion when the rod is withdrawn from the ground, the apparatus being characterized in that the arm cutter extends from the lower portion of the guide rod at right angles therewith, the apparatus having a first drive assembly for rotating the arm cutter about its own axis in a manner remotely controllable on the ground when the guide rod is inserted into and withdrawn from the ground, and a second drive assembly for revolving the arm cutter about the axis of the guide rod in a manner remotely controllable on the ground when the guide rod is withdrawn from the ground. With the ground improving apparatus of the present invention, the bit and the arm cutter are rotated each about its own axis by the first drive assembly when the guide rod is to be inserted into the -ground. The bit and the arm cutter thus rotated excavate the ground, guiding the rod into the ground. When the rod is inserted into the ground to a predetermined depth, the arm cutter is revolved about the axis of the guide rod by the second drive assembly while holding the bit and the arm cutter in rotation about their axes. The rotation and revolution of the arm cutter agitate a circular portion of the ground having a radius corresponding to the length of the arm cutter. While slowly lifting the rod with the bit maintained in rotation and the arm cutter in rotation and revolution, a ground improving liquid agent is injected from the discharge outlets into the portion of the ground agitated by the rotation, whereby the ground can be improved with a greatly increased efficiency over a wide area having a radius corresponding to the length of the arm cutter. Further because the arm cutter in rotation progressively excavate the ground with the insertion of the rod into the ground, there is no need to provide a complex structure wherein the arm cutter is adapted to be stowed in the rod and made extendable therefrom. Accordingly the present apparatus is simple in construction and easy to operate, assuring an improved work efficiency. Embodiments of the present invention will be described below with reference to the accompanying drawings, in which: Fig. 1 is a front view showing an apparatus of the single arm cutter type embodying the invention; Fig. 2 is an enlarged view in vertical section of arm cutters shown in Fig. 1; Fig. 3 is a front view showing the apparatus of Fig. 1 in operation to improve the ground; Fig. 4 is a diagram showing the position of a cleaning arm while a guide rod is being lifted during the operation of the apparatus of Fig. 1; Fig. 5 is a plan view schematically showing ground portions improved by the apparatus of Fig. 1 and formed continuously; Fig. 6 is a similarly view showing ground portions improved by the apparatus of Fig. 1 and formed continuously in a different arrangement; Fig. 7 is a front view showing an apparatus of the double arm cutter type embodying the invention; ; Fig. 8 is an enlarged view in vertical section showing double arm cutters of the apparatus of Fig. 1; Fig. 9 is a front view of Fig. 8; Fig. 10 is a view in section taken along the line X-X in Fig, 9; - Fig. 11 is. a view showing the arrangement of spur gears included in the apparatus of Fig. 7; and Fig. 12 is a front view showing the apparatus of Fig. 7 in operation to improve the ground. Figs. 1 to 4 show a ground improving apparatus of the single arm cutter type according to the invention. A guide rod 1 has at its lower end a bit 2 rotatable about its own axis by being controlled on the ground and arm cutters 3 extending from a lower portion of the rod 1 at right angles thereto. The arm cutters 3 are revolvable about the axis of the guide rod and are also each rotatable about its own axis by being controlled on the ground. While two arm cutters 3 are shown as spaced apart by an angle of 1800 about the rod 1, at least one arm cutter 3 may be provided. It is required that the cutter portion of the arm cutter 3 be so constructed as to excavate the ground and agitate the soil when rotating. The arm cutter 3 illustrated comprises a group of cutter blades 3a aligned on its arm axially thereof at a spacing in upper and lower two rows. The cutter portion may have some other different construction. To control the arm cutters 3 and the bit 2 on the ground for rotation, the rod 1 has a double pipe structure comprising inner and other pipes la and 1b as shown in detail in Fig. 2. The inner pipe la and the outer pipe lb are respectively supported in their upper portions and rotated by drive means 4 and 5 of a boring machine A installed on the ground as seen in Fig. 1. As shown in Fig. 2, the lower end of the inner pipe la of the rod 1 is coupled by a bevel gear transmission mechanism 6 to a horizontal shaft 3b extending through a lower portion of the outer pipe lb, whereby the arm cutters 3, 3 fixedly mounted on opposite ends of the horizontal shaft 3b are rotated each about its own axis. The shaft 3b is further coupled by a bevel gear transmission mechanism 7 to a stem 2a of the bit 2 which stem is positioned immediately below the shaft 3b to rotate the bit 2. Since the shaft 3b fixedly supporting the cutter arms 3 thereon extends through the outer pipe Ib, the outer pipe, when rotated by the drive means 5, revolves the arm cutters 3 about the axis of the outer pipe lb. The mechanism for effecting the rotation and revolution may be of some other type. To inject cement milk, cement-bentonite mixture or like ground improving liquid agent (grout) into the agitated ground portion through the bit 2 and each of the arm cutters 3, the arm cutter 3 and the bit 2 are respectively formed with liquid channels 9a and 9a' having discharge outlets 8 and 8'. These liquid channels 9a and 9a' are in communication with a liquid channel 9b formed in the lower portion of the outer pipe lb and communicating with a liquid channel 9c formed in the inner pipe la, whereby the channels 9a and 9a' are made to communicate with a liquid agent feeder 10 on the ground (see Figs. 1 and 3). A feeder 10 is connected to the upper portion of the inner pipe la by a swivel joint 17. Although the outlets 8 and 8' are shown as provided at the forward end of the arm 3 and at the forward end of the bit 2, such outlets may be formed at some other suitable portions additionally or without providing them at these ends. To clean the cutter portion of each arm cutter 3, a cleaning arm 11 having a comb-like portion lla is provided on a lower peripheral side portion of the outer pipe lb of the guide rod 1, in parallel with the arm cutter 3 so as to freely revolve about the axis of the arm cutter 3. The comb-like portion lla is in mesh with the cutter blades 3a of the cutter portion which are arranged like comb teeth. The cleaning arm 11 is provided at its base end and forward end with annular portions llb and lic concentric with the arm cutter 3. The base end annular portion llb is rotatably supported by a support portion lb' at the lower peripheral side part of the outer pipe Ib, while the forward end annular portion llc is similarly supported by a forward end rod portion of the arm cutter 3. A plurality of such cleaning arms 11 may be provided for each arm cutter 3. Indicated at 12a in Fig. 2 is a circumferential groove formed in the inner periphery of the base end annular portion llb, at 12b an annular projection formed on the outer periphery of the support portion lb' and loosely fitting in the circumferential groove 12a, and at 13 a bearing for the forward end annular portion llc. When the ground is to be improved with use of the apparatus of the invention, the inner pipe la and the outer pipe lb of the guide rod 1 are respectively held to the drive means 4 and 5 of the boring machine A as shown in Figs. 1 and 3. The drive means 4 and 5 are mounted on a lift member a3 which is movable upward and downward along a guide rail a2 by lift means al Fig. 1 shows the apparatus when it is about to start operation. When the inner pipe la is rotated by the drive means 4 in this state, the arm cutters 3 and the bit 2 are rotated each about its own axis. In the state of Fig. 1, the drive means 5 is out of operation to hold the outer pipe lb at rest, so that the arm cutters 3 are not revolved. As the lift member a3 is lowered along the guide rail a2 by the lift means al from the position shown in Fig. 1, the bit 2 and the arm cutters 3 vertically bore the ground while guiding the guide rod 1 into the ground. While the guide rod 1 is thus being guided into the ground, each cleaning arm 11 is subjected to the resistance of soil and is positioned on the rear side-of the arm cutter 3 with respect to the direction of excavation, i.e., vertically above the arm cutter 3 (see Fig. 2), thus smoothly following the arm cutter 3 into the soil excavated and agitated by the cutter. When clayey soil adheres to the cutter portion of the arm cutter 3, the cleaning arm 11 acts to scrape the soil off the cutter portion. Since the cleaning arm 11 is substantially held to the position vertically above the arm cutter 3 by being subjected to the resistance of excavation, the cleaning arm 11 effectively cleans the cutter arm with stability in position without any likelihood that it will rotate with the arm cutter 3. When a predetermined depth is reached within the ground as seen in Fig. 3, the drive means 5 is driven to rotate the outer pipe 1b while rotating the bit 2 and the arm cutters 3 through the inner pipe la, whereupon the arm cutters 3 start to revolve while rotating to excavate and agitate the soil within the range of its revolution. Accoridngly the guide rod 1 is gradually lifted while injecting a ground improving liquid agent into the agitated soil within the range of the revolution through the outlets 8 and 8' of the cutters 3 and the bit 2, whereby the ground within the above range can be improved at once. If there is an obstacle in the ground to hinder the revolution of the arm cutters 3 during the lift of the guide rod 1, the arm cutters 3 may be held out of revolution until the obstacle is cleared while being held in rotation only. During the operation of the arm cutters 3 involving their rotation and revolution, the cleaning arms 11 are positioned behind the arm cutters 3 with respect to the direction of excavation as seen in Fig. and are substantially held in this position by being subjected to the resistance of soil, thus effectively cleaning the cutters as contemplated while smoothly passing through the excavated and agitated soil in the same manner as when advancing into the ground. With reference to Fig. 4, an arrow 13 shows the direction of revolution of the arm cutters 3, an arrow 14 shows the direction of lift of the guide rod 1, and an arrow 15 indicates the direction of excavation. With use of the present apparatus, the ground can be improved at a time over a wide area covered by the revolution of the arm cutters 3 and having a radius corresponding to the length of each arm cutter 3. When such improved ground portions a are formed continuously in series as seen in Fig. 5, an underground continuous wall can be built with a large thickness, while if such portions are formed in rows in staggered arrangement as seen in Fig. 6, the ground can be improved over an increased area. Thus the present apparatus is very useful for forming an underground continuous wall of large thickness or for improving the ground over a wide area, as in soft ground. Throughout the entire process of excavation and agitation carried out by the present apparatus, the cleaning arms 11 clean the cutter portions of the arm cutters 3 to eliminate a adhesion of clayey soil that would impair the excavation-agitation efficiency, consequently assuring efficient improvement of the ground. Furthermore, the ground can be improved by the apparatus of the invention with its arm cutters held in their extended position without the necessity of stowing and extending the cutters unlike the conventional apparatus. The apparatus is therefore simple in construction and easy to operate for the improvement of the ground. Figs. 7 to 12 show an apparatus of the double arm cutter type embodying the present invention. With the apparatus of this type, arm cutters 3 are arranged one above another in a multiplicity of stages and aligned vertically, and groups of cutter blades 3a providing cutter portions at different levels are in mesh with each other to clean eath other. With the exception of this feature, this type has substantially the same construction as the single type already described. Throughout the drawings, like parts are referred to by like reference numerals. With this type, the arm cutters 3 arranged one above another in multi-stages, for examples, upper and lower arm cutters 3, 3 arranged in two stages are coupled together at horizontal shafts 3b, 3b by spur gears 16a, 16b and 16c. To rotate the upper and lower arm cutters 3 at different speeds, the spur gears 16a and 16c are different in diameter. The intermediate gear 16b functions to rotate the upper and lower arm cutters 3, 3 in the same direction to reduce the likelihood that soil will engage in between the cutter portions of the arm cutters 3. The apparatus of the second type, in which the arm cutters 3 are arranged one above another in multistages, can improve the ground more efficiently than the apparatus of the single arm cutter type.

Claims: CLAIMS: 1. An apparatus for improving ground comprising a guide rod to be inserted into the ground to a predetermined depth, a bit attached to the forward end of the guide rod and rotatable when the rod is inserted into the ground to guide the rod into the ground, the bit having a discharge outlet for injecting a ground improving liquid agent into an agitated portion of the ground while the rod is withdrawn from the ground with the bit held in continued rotation, and at least one arm cutter having a discharge outlet and attached to a lower portion of the guide rod for agitating the ground and simultaneously injecting the ground improving agent into the agitated ground portion when the rod is withdrawn from the ground, the apparatus being characterized in that the arm cutter extends from the lower portion of the guide rod at right angles therewith, the apparatus having a first drive assembly for rotating the arm cutter about its own axis in a manner remotely controllable on the ground when the guide rod is inserted into and withdrawn from the ground, and a second drive assembly for revolving the arm cutter about the axis of the guide rod in a manner remotely controllable on the ground when the guide rod is withdrawn from the ground. 2. An apparatus as defined in claim 1 wherein the guide rod has a double pipe structure including an inner pipe and an outer pipe, the first drive assembly including (a) the inner pipe, (b) first drive means installed above the ground and holding the upper end of the inner pipe for rotating the inner pipe and (c) a rotation transmitting mechanism for transmitting the rotation of the inner pipe by the drive means to the bit and the arm cutter as rotation about their own axes, the second drive assembly including (d) the outer pipe, (e) second drive means installed above the ground and holding the upper end of the outer pipe for rotating the outer pipe and (f) a mechanism for transmitting the rotation of the outer pipe by the second drive means to the arm cutter as revolution about the axis of the guide rod. 3. An apparatus for improving ground comprising a guide rod to be inserted into the ground to a predetermined depth, a bit attached to the forward end of the guide rod and rotatable when the rod is inserted into the ground to guide the rod into the ground, the bit having a discharge outlet for injecting a ground improving liquid agent into an agitated portion of the ground while the rod is withdrawn from the ground with the bit held in continued rotation, and at least one arm cutter having a discharge outlet and attached to a lower portion of the guide rod for agitating the ground and simultaneously injecting the ground improving agent into the agitated ground portion when the rod is withdrawn from the ground, the apparatus being characterized in that the arm cutter extends from the lower portion of the guide rod at right angles therewith, the apparatus having a first drive assembly for rotating the arm cutter about its own axis in a manner remotely controllable on the ground when the guide rod is inserted into and withdrawn from the ground, and a second drive assembly for revolving the arm cutter about the axis of the guide rod in a manner remotely controllable on the ground then the guide rod is withdrawn from the ground, the arm cutter being provided with a cleaning arm having cleaning blades in mesh with the cutter portion of the arm cutter, the cleaning arm being parallel with the arm cutter and freely revolvable about the axis of the arm cutter. 4. An apparatus as defined in claim 3 wherein the guide rod has a double pipe structure including an inner pipe and an outer pipe, the first drive assembly including (a) the inner pipe, (b) first drive means installed above the ground and holding the upper end of the inner pipe for rotating the inner pipe and (c) a rotation transmitting mechanism for transmitting the rotation of the inner pipe by the drive means to the bit and the arm cutter as rotation about their own axes, the second drive assembly including (d) the outer pipe, (e) second drive means installed above the ground and holding the upper end of the outer pipe for rotating the outer pipe and (f) a mechanism for transmitting the rotation of the outer pipe by the second drive means to the arm cutter as revolution about the axis of the guide rod. 5. An apparatus forimproving ground comprising a guide rod to be inserted into the ground to a predetermined depth, a bit attached to the forward end of the guide rod and rotatable when the rod is inserted into the ground to guide the rod into the ground, the bit having a discharge outlet for injecting a ground improving liquid agent into an agitated portion of the ground while the rod is withdrawn from the ground with the bit held in continued rotation, and arm cutters each having a discharge outlet and attached to a lower portion of the guide rod for agitating the ground and simultaneously injecting the ground improving agent into the agitated ground portion when the rod is withdrawn from the ground, the apparatus being characterized in that the arm cutters are arranged one above another in a multiplicity of stages and aligned vertically, the arm cutter in each stage having a group of cutter blades spaced apart axially of the arm cutter and arranged in at least one row, the groups of cutter blades in each two adjacent stages being in mesh with each other, the apparatus having a first drive assembly for rotating the arm cutters each about its own axis in a manner remotely controllable on the ground when the guide rod is inserted into and withdrawn from the ground, and a second drive assembly for revolving the arm cutters about the axis of the guide rod in a manner remotely controllable on the ground when the guide rod is withdrawn from the ground. 6. An apparatus as defined in claim 5 wherein the guide rod has a double pipe structure including an inner pipe and an outer pipe, the first drive assembly including (a) the inner pipe, (b) first drive means installed above the ground and holding the upper end of the inner pipe for rotating the inner pipe and (c) a rotation transmitting mechanism for transmitting the rotation of the inner pipe by the drive means to the bit and the arm cutters as rotation about their own axes, the second drive assembly including (d) the outer pipe, (e) second drive means installed above the ground and holding the upper end of the outer pipe for rotating the outer pipe and (f) a mechanism for transmitting the rotation of the outer pipe by the second drive means to the arm cutters as revolution about the axis of the guide rod. 7. An apparatus as defined in claim 5 wherein the arm cutters differ from stage to stage in the direction of rotation or in the speed of rotation. 8. A method of improving ground characterized by inserting into the ground a guide rod equipped with ,a bit at its forward end and an arm cutter transversely extending from the lower portion of the guide rod by guiding the rod by the rotation of the bit and the rotation of the arm cutter about its own axis, and gradually withdrawing the guide rod from the ground when the rod has reached a predetermined depth while revolving the arm cutter about the axis of the rod in addition to its rotation to agitate the portion of the ground covered by the revolution and while injecting a liquid agent into the agitated portion of the ground from discharge outlets in the arm cutter and the bit.

Inventors: MIYAZAKI, YASUO, NAKAMASU, SEIJI, TSURUOKA, TANEHIDE, UGA, TERUO, YOSHIDA, MITSURU
Applicants: OSAKA BOSUI KENSETSUSHA KK, ZENITAKA COOPER THE
Application year: 1983
Main classification: E02D3
IPC codes: E02D3