Liquefaction prevention method for sewer conduit as well as underground installation, and device used therefor

Abstract

To provide a liquidation prevention method capable of preventing the ground for a sewer conduit or an underground installation from being liquidated, and a device used therefor.SOLUTION: A liquidation prevention method is to construct a crushed rock pile 153 by forming an excavation hole 161 to a lower part of a sewer pipe 152 with a rod 9 and a casing pipe 10 using the rod 9 inserted into the ground through rotation by a rotation driven device 7 and a casing pipe 10 sleeved around the rod 9 and inserted into the ground, on which an outer periphery a crushed stone charging port 21, and to charge crushed stones 22 in the excavation hole 161. Constructing the crushed tone pile 153 to a lower part of the sewer pipe 152 from the ground surface G by charging the crushed stones 22 into the excavation hole 161 formed to a lower part of the sewer pipe 152 allows liquidation to be prevented and installation such that large side earth pressure on the sewer pipe 152 is not applied because of the casing pipe 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for preventing liquefaction of sewerage pipelines and underground buried objects, and an apparatus used therefor. [Background technology]

[0002] For example, one type of structure for preventing a manhole, which is a sewer pipe, from floating up during an earthquake is a structure (e.g., Patent Document 1) in which a drilling bolt penetrates the base slab of a sewer manhole from symmetrical positions on either side of the sewer channel on the cast-in-place concrete base slab, drills a hole in the liquefied layer while preventing soil collapse with an outer pipe, and then drills a hole to a specified depth in the non-liquefied layer.After that, the outer pipe is removed while leaving the drilling bolt in place, and a solidifying material is injected to form a pile-shaped anchor, and the top of the drilling bolt is fixed to the top of the cast-in-place concrete base slab with a washer and nut.

[0003] The manhole lift-up prevention structure requires work to be done inside the manhole, which poses the problem that the manhole cannot be used during construction.

[0004] In response to this, a method of preventing liquefaction of ground using large machinery involves absorbing and dissipating the pore water pressure in soil particles caused by seismic motion using highly permeable sand piles or crushed stone piles. A method that utilizes this concept as a liquefaction prevention measure for detached residential areas, etc., is the liquefaction prevention method (for example, Patent Document 2), and the effectiveness of the liquefaction prevention method has been demonstrated against large earthquakes.

[0005] Furthermore, the crushed stone pillars made using the liquefaction prevention method have high water permeability, and during an earthquake, the water pressure generated in the ground can be dissipated in the gaps within the crushed stone pillars, preventing liquefaction in the ground.These pillars are easy to work with and can efficiently compact the filling material, providing high bearing capacity.

[0006] In the liquefaction prevention method of constructing crushed stone piles as described above, crushed stone is poured into the bottom of the designed borehole in a specified layer thickness in order to improve the bearing capacity of the building ground and prevent liquefaction, and the piled up crushed stone is compacted by rolling. By repeating this process, crushed stone columns are constructed while consolidating the surrounding ground. Therefore, if this construction method is used to construct existing sewer pipes and underground buried objects, the horizontal expansion of the crushed stone will generate lateral earth pressure on the sewer pipes, which may cause horizontal displacement of underground buried objects such as sewer manholes and pipes, septic tanks, etc., or damage due to partial pressure.

[0007] In Patent Document 2, a lifting means is provided on the leader so that it can be raised and lowered, and the double pipe is inserted into the ground by this lifting means, but since the maximum depth of the crushed stone pile is determined by the length of the double pipe, the length of the double pipe becomes long in order to form a deep crushed stone pile. Therefore, when attempting to use this for construction of sewerage pipes buried under roads or underground buried objects, for example, there is a problem that it is difficult to construct a crushed stone pile to the desired depth because of the overhead crossing wires such as electric wires that are strung above the road.

[0008] In addition, in the device of Patent Document 2, filler materials such as gravel and crushed stone are stored in a storage section of a vehicle body equipped with a leader, and when loading, the filler material is supplied from the loading port to the opening of the excavation hole by driving the belt conveyor in accordance with the sinking speed of the filler material, and a crushed stone pile is constructed with the filler material. In this case, to load crushed stone on the loading platform with a backhoe, it is necessary to make multiple round trips between the temporary crushed stone storage site and the vehicle with the filler material stored in the bucket, and there is a problem that the operation of the backhoe to transport the crushed stone increases expenses. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Utility Model Registration No. 3148230 [Patent Document 2] Patent No. 3669288 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0010] The problem to be solved is to provide a liquefaction prevention method for sewer pipelines and underground buried objects that can prevent liquefaction of the ground of the sewer pipelines or underground buried objects, and an apparatus used therefor, and in addition, to provide a liquefaction prevention method for sewer pipelines and underground buried objects that can be constructed without applying large lateral pressure to the sewer pipelines or underground buried objects, and an apparatus used therefor. [Means for solving the problem]

[0011] The invention of claim 1 is characterized by using a rod that is rotated by a rotary drive device and inserted into the ground, and a casing pipe that is attached to the rod and has a crushed stone inlet on its outer periphery and is inserted into the ground, and by using the rod and the casing pipe to form a borehole down to below a sewer pipeline or underground buried object, and by pouring crushed stone into this borehole to construct a crushed stone pile.

[0012] The invention of claim 2 is characterized in that the construction is performed on the existing sewerage pipeline or underground buried object while it is still in use.

[0013] The invention of claim 3 is characterized in that after the casing pipe and the lower part of the rod are inserted into the ground, the rod is disconnected from the rotary drive device, the rotary drive device is moved upward, and below the rotary drive device, the lower end of an extension casing pipe and the lower end of an extension rod are connected to the upper end of the casing pipe and the upper end of the rod.

[0014] The invention of claim 4 is an apparatus used in the liquefaction prevention method for sewerage pipelines and underground buried objects described in claim 1, characterized in that a self-propelled vehicle is provided with a loading platform for loading crushed stone and a loading / unloading device for loading and unloading the crushed stone onto the loading platform.

[0015] The invention of claim 5 is an apparatus used in the liquefaction prevention method for sewerage pipelines and underground buried objects described in claim 1, characterized in that it is provided with an inlet for injecting crushed stone into the crushed stone inlet, and the inlet is provided with a flexible tip portion.

[0016] The invention of claim 6 is characterized in that, in the device used in the liquefaction prevention method for sewerage pipelines and underground buried objects described in claim 1, it is provided with an opening / closing means for opening and closing the multiple crushed stone inlets. Effect of the Invention

[0017] According to the configuration of claim 1, by pouring crushed stone into an excavation hole formed below the sewer pipeline or underground buried object, a crushed stone pile can be constructed from the ground to below the sewer pipeline or underground buried object, thereby making it possible to prevent liquefaction, and the casing pipe can be used to construct the structure so that large lateral earth pressure is not applied to the sewer pipeline or underground buried object.

[0018] According to the configuration of claim 2, there is no need to stop using existing sewerage pipelines or underground buried objects before carrying out construction work.

[0019] According to the configuration of claim 3, after the casing pipe and rod are inserted into the ground, an extension casing pipe and an extension rod can be added to the casing pipe and rod, thereby reducing the overall height dimension of the device and allowing construction to be carried out.

[0020] According to the configuration of claim 4, crushed stone can be supplied by a self-propelled vehicle equipped with a loading / unloading device and a loading platform, making it possible to carry out construction work continuously and at the same time reducing the number of trips back and forth between the crushed stone yard and the construction site.

[0021] According to the configuration of claim 5, the flexible tip portion can be brought into contact with the outer surface of the casing pipe, allowing the crushed stone to be smoothly charged into the crushed stone charging port.

[0022] According to the configuration of claim 6, by closing the crushed stone inlet, when the casing pipe is inserted into the ground, it is possible to prevent the soil and sand inside from leaking from the crushed stone inlet above ground, and also to prevent soil and sand from underground from entering the casing pipe through the crushed stone inlet when the groundwater level is high. [Brief description of the drawings]

[0023] [Figure 1] 1 is an overall cross-sectional view showing a first embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] FIG. 1 is a front view of the casing pipe and the lid body. [Figure 4] FIG. 13 is a cross-sectional explanatory view of the upper part of the anti-vibration frame and the casing pipe. [Diagram 5] FIG. 1 is a cross-sectional plan view of the anti-vibration frame and the upper part of the casing pipe. [Figure 6] FIG. 2 is a cross-sectional view of the main parts of the casing pipe and the lid body of the same. [Figure 7] FIG. 2 is a cross-sectional view of the opening and closing fixing means of the same. [Figure 8] FIG. 8(A) is a front view of a connection portion of a casing pipe, and FIG. 8(B) is an enlarged plan view of an upper portion of the casing pipe. [Figure 9] FIG. 13 is a front view of the connection portion of the casing pipe. [Figure 10] FIG. [Figure 11] FIG. 2 is an enlarged plan view of the upper part of the casing pipe. [Figure 12] FIG. 2 is a cross-sectional view of the casing pipe and the connecting cover of the same. [Figure 13] FIG. 13(A) is a cross-sectional view of the female joint, and FIG. 13(B) is a front view of the male joint. [Figure 14] FIG. [Figure 15] FIG. 11 is a perspective view of the input path as seen from the side of the same. [Figure 16]FIG. 16(A) is a perspective view of the insertion path as seen from above, and FIG. 16(B) is a plan view of the tip end of the side portion of the hair. [Figure 17] FIG. 13 is an explanatory diagram of multiple connected casing pipes and rods. [Figure 18] Same as above, a front view showing the disconnection of the casing pipe and the connecting cover, where Fig. 18(A) shows the connected state, Fig. 18(B) shows the state after the connection is disconnected and the rotary drive device has risen along the rod, and Fig. 18(C) shows the state after the male and female joints have been disconnected and the rotary drive device has risen. [Figure 19] FIG. 11 is a front view illustrating the operation of connecting the casing pipe and the extension casing pipe. [Figure 20] FIG. 13 is an explanatory cross-sectional view of the first embodiment at the start of excavation. [Figure 21] FIG. 13 is a cross-sectional view of the tip bit when it reaches a specified excavation depth. [Figure 22] FIG. 11 is a cross-sectional view illustrating the step of horizontally spreading the piled up filling material. [Diagram 23] Same as above, this is a cross-sectional explanatory diagram explaining the construction of the crushed stone consolidation section. [Figure 24] FIG. 13 is a cross-sectional explanatory diagram illustrating the construction of a columnar crushed stone pile. [Diagram 25] Same as above, a cross-sectional explanatory diagram of the columnar crushed stone pile after construction has been completed. [Figure 26] FIG. 11 is a front view of an extension casing pipe showing a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Preferred embodiments of the present invention will be described with reference to the accompanying drawings. Note that the embodiments described below do not limit the contents of the present invention described in the claims. Also, not all of the configurations described below are necessarily essential requirements of the present invention. EXAMPLES

[0025] A first embodiment of the present invention will be described with reference to Fig. 1 to Fig. 25. As shown in the figures, a ground improvement device 1 has an endless track 3 as a traveling means attached to the bottom of a self-propelled vehicle body 2 as the main body, and this endless track 3 is driven by a prime mover (not shown) mounted on the vehicle body 2. In addition, a leader 5 is provided in the front of the vehicle body 2 so as to be capable of being raised and lowered, and this leader 5 can be raised and lowered by a raising and lowering device (not shown) in the front-rear direction.

[0026] A guide rail 6 is provided in front of the leader 5, and a rotation drive device 7 is provided on the guide rail 6 so as to be movable up and down, and an elevation drive device 8 is provided for elevation and down of the rotation drive device 7. The rotation drive device 7 includes an insertion portion 11 through which a base end rod 9K is inserted, and a rod lock 12 capable of locking and unlocking the rods 9, 9A, 9S, and 9K. With the rod 9 locked by the rod lock 12, the rod lock 12 rotates to rotationally drive the rods 9, 9A, 9S, and 9K.

[0027] A vibration-prevention frame 13 is provided in front of the vehicle body 2. This vibration-prevention frame 13 has frame body attachment parts 14, 14 fixed in the above-mentioned direction on the left and right front sides of the vehicle body 2, and a frame body 15 for preventing the vibration of the casing pipe 10 is provided on these frame body attachment parts 14, 14. This frame body 15 is located in front of the leader 5, and the casing pipes 10, 10A are inserted into the frame body 15 so as to be movable up and down.

[0028] The frame body 15 consists of a central split frame portion 16C fixed between the frame body mounting portions 14, 14, and left and right split frame portions 16L, 16R connected to the left and right frame body mounting portions 14, 14 by pivotal connecting portions 17, 17 so as to be horizontally rotatable. By closing the left and right split frame portions 16L, 16R and locking the tips of the left and right split frame portions 16L, 16R together by locking means 18, a circular frame body 15 is formed by the split frame portions 16C, 16L, 16R.

[0029] Then, the locking means 18 is released, and the lower parts of the casing pipes 10, 10A are placed inside the left and right separate frame parts 16L, 16R with the left and right separate frame parts 16L, 16R open as shown by the imaginary lines in Fig. 5, and the left and right separate frame parts 16L, 16R are closed and the tips of the left and right separate frame parts 16L, 16R are connected to each other by the locking means 18, so that the casing pipe 10 is loosely inserted into the frame body 15 in an anti-sway state. The inner diameter of the frame body 15 is, for example, 400 mm (millimeters), and the outer diameter of the casing pipe 10 is about 355 mm.

[0030] An extension casing pipe 10A is provided to be connected to the casing pipe 10, and this extension casing pipe 10A is shorter than the casing pipe 10. The casing pipes 10, 10A are provided with a plurality of crushed stone inlets 21 spaced apart along their length, and the crushed stone inlets 21 are filler inlets. The interval between adjacent crushed stone inlets 21, 21 in the vertical direction is the same as the vertical dimension of the crushed stone inlets 21.

[0031] An extension rod 9A is provided which is connected to the rod 9, and this extension rod 9A is shorter than the rod 9. In addition, the casing pipes 10, 10A may be rotated together with the rods 9, 9A, 9S, 9K in some cases, and the casing pipes 10, 10A may not be rotated and only the rods 9, 9A, 9S may be rotated.

[0032] Even when only the rods 9, 9A, 9S are driven to rotate, the rotation of the rods 9, 9A, 9S within the casing pipes 10, 10A containing soil and sand creates a force that rotates the casing pipes 10, 10A in the same direction as the rods 9, 9A, 9S. To cope with this, a rotation prevention means 31 is provided to prevent the casing pipes 10, 10A from rotating, and the rotation prevention means 31 is used to stop the casing pipes 10, 10A from rotating, thereby making it possible to keep the orientation of the crushed stone inlet 21 constant.

[0033] As shown in Figures 3 and 4, the anti-rotation means 31 comprises a longitudinal hole 32 drilled in the casing pipes 10, 10A to serve as an anti-rotation hole, and as shown in Figure 5, a anti-rotation hole 33 communicating with the long hole 32 is provided in the left split frame part 16L, which is one of the left and right split frame parts 16L, 16R, and a pin-shaped or plate-shaped rod member 34 is inserted into the long hole 32 and the anti-rotation hole 33. This prevents the casing pipes 10, 10A from rotating relative to the frame body 15, and allows the casing pipes 10, 10A to move up and down within the range of the long hole 32.

[0034] Furthermore, the anti-rotation means 31 prevents the casing pipes 10, 10A from rotating relative to the frame body 15. In this state, when the rods 9, 9A, 9S, 9K rotate, a force is applied to rotate the casing pipes 10, 10A. This force presses the rod-shaped member 34 against the edge of the long hole 32, so that the rod-shaped member 34 does not fall out.

[0035] Further, reinforcing members 40 are provided corresponding to the long holes 32 to prevent the long holes 32 from expanding in the width direction. The reinforcing members 40 are made of steel bars or the like, and both ends are fixed to the inner surface of the casing pipes 10, 10A on both sides of the long holes 32. The reinforcing members 40 are shorter than the inner diameter of the casing pipes 10, 10A, and are provided at a length and position such that they do not come into contact with the rods 9 inside the casing pipes 10, 10A, and do not come into contact with the rod-shaped members 34. The reinforcing members 40 are disposed at equal intervals, for example, 300 mm intervals, in the longitudinal direction of the casing pipes 10, 10A.

[0036] As shown in Figures 4 to 6, the apparatus is provided with an opening / closing means 41 for opening and closing the crushed stone inlet 21. The opening / closing means 41 has a cover 42 to be placed on the inner surface of the casing pipes 10, 10A, and the cover 42 is made of a strip-shaped steel plate having a constant width on both sides and is curved to correspond to the inner surface of the casing pipes 10, 10A.

[0037] In addition, the cover body 42 is wider than the left-right width of the crushed stone inlet 21, and has a communicating opening 43 of the same shape as the crushed stone inlet 21 that communicates with the crushed stone inlet 21, and between adjacent communicating openings 43, 43 vertically is a blocking portion 44 that can block the crushed stone inlet 21, and the vertical spacing of this blocking portion 44 is formed to be the same as the vertical dimension of the crushed stone inlet 21, and by sliding the cover body 42 up and down, multiple (all) crushed stone inlets 21 can be switched between an open state and a closed state.

[0038] The opening / closing means 41 also includes a longitudinal guide member that guides the lid 42 up and down along the inner surface of the casing pipe 10, 10A, and left and right rails 45, 45 are provided in the longitudinal direction of the casing pipe 10, 10A as the guide member. The left and right rails 45, 45 hold the left and right edges of the lid 42 and have a substantially L-shaped configuration including an attachment piece 45A whose base end is fixed to the inner surface of the casing pipe 10, 10A and a holding piece 45B provided at the tip of the attachment piece 45A and positioned on the inner surface side of the lid 42.

[0039] Furthermore, a support member 46 is provided on the inner surface of the casing pipe 10, 10A as a stopper that supports the lower edge of the lid 42 in the closed state in the circumferential direction, and this support member 46 is substantially L-shaped and has an attachment piece 46A whose base end is fixed to the inner surface of the casing pipe 10, 10A and a holding piece 46B provided at the tip of this attachment piece 46A and positioned on the inner surface side of the lid 42, and the lower edge of the lid 42 in the closed state abuts on the upper surface of the attachment piece 46A. Note that the support member 46 may be only the attachment piece 46A as a stopper, without the holding piece 46B.

[0040] In this manner, when the cover 42 is lowered relative to the casing pipes 10, 10A, the crushed stone inlet 21 is blocked by the blocking portion 44, and when the cover 42 is raised, the communication opening 43 communicates with the crushed stone inlet 21, forming the crushed stone inlet 21.

[0041] In addition, in order to open the crushed stone inlet 21 by sliding the cover body 42 relative to the casing pipes 10, 10A, a slide hole 51, which is a long hole in the longitudinal direction, is provided at the top of the casing pipes 10, 10A, and a cover body hole 52 is drilled in the cover body 42 corresponding to this slide hole 51, and a lock bolt 53, which is a pin-shaped operating body, is inserted into these slide hole 51 and cover body hole 52.

[0042] In this example, with the horizontal lock bolt 53 inserted into the slide hole 51 and the lid hole 52, the position where the lock bolt 53 abuts against the upper edge of the slide hole 51 is the closed position of the crushed stone inlet 21, and the position where the lock bolt 53 abuts against the lower edge of the slide hole 51 is the open position of the crushed stone inlet 21. The lock bolt 53 fits into the lid hole 52.

[0043] Furthermore, when the casing pipe 10 is first inserted into the ground, the upper spiral blade 84 enters the interior until the upper edge 82F of the lower spiral blade 82 abuts against the lower edge of the casing pipe 10, so the positions of the lowermost rod-shaped member 34 and support member 46 are set at a position away from the lower end of the casing pipe 10 so that the upper spiral blade 84 does not come into contact with them once inside.

[0044] It also has an open / fixing means 55 for fixing the lid body 42 in the open position, and this open / fixing means 55 has a through hole 55T drilled in the casing pipes 10, 10A, a female threaded hole 55M formed in the lid body 42 and communicating with the through hole 55T in the closed position, and a bolt 56 inserted into the through hole 55T and screwed into the female threaded hole 55M.

[0045] Similarly, the closure fixing means 57 for fixing the lid body 42 in the closed position is provided, and the closure fixing means 57 includes a through hole 57T drilled in the casing pipes 10, 10A, a female screw hole 57M formed in the lid body 42 and communicating with the through hole 57T in the closed position, and a bolt 58 inserted into the through hole 57T and screwed into the female screw hole 57M. The female screw hole 57M protrudes from the left edge of the lid body 42 and is drilled in the protruding piece 42F, and the upper end of the left rail 45 is in a position where it does not come into contact with the protruding piece 42F. The above description of the combination of the casing pipes 10, 10A is also applicable to the combination of the casing pipes 10A, 10A.

[0046] The pipe connecting means 60 connects the upper and lower casing pipes 10, 10A and the casing pipes 10A, 10A. Although the connecting structure of the casing pipes 10, 10A will be described as an example, the connecting structure of the casing pipes 10A, 10A is also similar.

[0047] The pipe connecting means 60 has a connecting receiver 61 provided on the inner surface of the upper part of the lower casing pipe 10, and a connecting device 71 connected to the connecting receiver 61 provided at the lower end of the upper casing pipe 10A.

[0048] The connecting receiver 61 has an engaging protrusion 62 to which the connecting device 71 engages, and this engaging protrusion 62 is an arc-shaped band plate fixed to the inner surface of the casing pipe 10, and is fixed in a pair at positions opposite the inner surface of the casing pipe 10, has constant vertical dimensions and a constant thickness, and is provided in the left-right center with a positioning abutment 63 that protrudes toward the center of the casing pipe 10.

[0049] The connector 71 is in the form of a vertically long plate, with the outer surface of a base end 72 fixed to the inner surface of the lower end of the casing pipe 10A, and a pair of tip ends 73 provided at opposing positions protruding downward from the lower edge of the casing pipe 10A. A locking recess 74 capable of being locked onto the locking projection 62 is formed on the outer surface of the tip of the tip end 73. An inclined guide surface 75 is formed on the outer surface of the tip end of the tip end 73.

[0050] When the lower edge of the upper casing pipe 10A is abutted against the upper edge of the lower casing pipe 10, the locking recess 74 is aligned with the height position of the locking protrusion 62. In this state, for example, when the upper casing pipe 10A is rotated, the locking protrusion 62 enters the locking recess 74, and the radial position of the upper casing pipe 10A is aligned with the lower casing pipe 10 at the position where the tip 73 of the connecting device 71 abuts against the positioning abutment portion 63, as shown in Figure 8.

[0051] Further, with the radial positions aligned, a female screw hole 73M communicating with an inward / outward through hole 62T drilled in the locking projection 62 is formed in the tip portion 73. Therefore, when the tip portion 73 of the connector 71 is in a position where it abuts against the positioning abutment portion 63, a bolt 65 can be inserted from the outer surface side into the through hole 62T and screwed into the female screw hole 73M, thereby connecting the upper and lower casing pipes 10, 10A.

[0052] In addition, since the through hole 62T is drilled on both the left and right sides of the positioning abutment portion 63, the upper casing pipe 10A can be rotated either counterclockwise or clockwise to engage the locking recess 74 with the locking receiving protrusion portion 62, and then fixed with the bolt 65.

[0053] In this example, when inserted into the ground, the crushed stone inlet 21 is located at the rear side (vehicle body 2 side) of the casing pipe 10, and the connecting receivers 61, 61 are arranged approximately on the left and right sides of the casing pipe 10. As shown by arrow Y in Figure 8, the casing pipe 10A is rotated counterclockwise so that the tip 73 of the connecting device 71 abuts the positioning abutment portion 63, and the connecting receivers 61, 61 are attached so that the pair of connecting devices 71, 71 are positioned on the left and right.

[0054] Therefore, the casing pipe 10A, which has a pair of connectors 71, 71 on the left and right, has the crushed stone inlet 21 on the rear side, so that the crushed stone inlet 21 of the lower casing pipe 10A and the crushed stone inlet 21 of the upper casing pipe 10A are lined up vertically.

[0055] As shown in FIG. 9, the pipe connecting means 60 is provided with a plate-shaped connecting member 77, which is fixed to the inner surface of one of the upper end of the lower casing pipe 10 and the lower end of the upper casing pipe 10A by welding or the like. In this example, the connecting member 77 is fixed to the lower end of the upper casing pipe 10A, and the tip of this connecting member 77 protrudes from the lower edge of the upper casing pipe 10A.

[0056] In addition, a female threaded hole 77M is formed in the portion protruding from the lower end of the connecting member 77, and when the casing pipes 10, 10A are connected, a through hole 77T communicating with the female threaded hole 77M is drilled in the lower casing pipe 10, and a bolt 78 inserted into the through hole 77T is screwed into the female threaded hole 77M, thereby connecting the casing pipes 10, 10A by the connecting member 77.

[0057] The connecting members 77 are provided in pairs at positions circumferentially spaced apart from the connecting members 71, 71 and facing each other. That is, Fig. 9 shows the connecting member 71 on the rear side where the crushed stone inlet 21 of the casing pipes 10, 10A is provided, but a connecting member 71 is also provided on the front side. The connecting member 77 of the connecting member 71 may be disposed on the inner surface side of the casing pipes 10, 10A.

[0058] Then, with the crushed stone inlet 21 closed by the lid 42 and the lid 42 fixed in position by the closing and fixing means 57, the rod 9 and the lower part of the casing pipe 10 are inserted into the ground as described below, and when the upper end of the casing pipe 10, which is, for example, 2.6 m (meters), reaches the position of the frame 15, the fixing of the rod 9 by the rod lock 12 is released, and the connection between the casing pipe 10 and the connecting lid 85 is released, and the rotation drive device 7 is raised to a position where the inside of the casing pipe 10 can be seen from the upper end. The frame 15 is, for example, at a height of about 1.2 m above the ground G.

[0059] The operation for lifting the rotary drive unit 7 will be described with reference to Fig. 18. Note that the frame 15 is not shown in Fig. 18. As shown in Fig. 18(A), from a state in which the connecting lid 85 is connected to the upper end of the casing pipe 10, the connecting lid 85 is rotated by an angle by the rotary drive unit 7 to release the connection between the connecting receiver 61 and the connecting device 71. If the lock of the rods 9, 9K by the rod lock 12 is released from this state, the rotary drive unit 7 and the connecting lid 85 fixed thereto can be moved upward by the lift drive unit 8, as shown in Fig. 18(B), and the upper end of the casing pipe 10 opens.

[0060] Furthermore, when connecting the casing pipe 10A and rod 9A to the casing pipe 10 and rod 9, in the state shown in Figure 18 (B), the connection between the male and female joints 91, 101 is released by removing the shear pin 100, and the base end rod 9K is locked by the rod lock 12.After that, the lifting drive device 8 can move the rotation drive device 7 and the base end rod 9K upward as shown in Figure 18 (C), and the rotation drive device 7 and the base end rod 9K are raised to a position where the extension rod 9A and extension casing pipe 10A can be connected to the rod 9 and casing pipe 10.

[0061] If the soil inside the casing pipe 10 is above the ground level G and the soil would fall out from the crushed stone inlet 21 when the crushed stone inlet 21 is opened, the rotary drive device 7 is lowered and the rod 9 is fixed by the rod lock 12. After fixing, the rod 9 is rotated in the direction opposite to excavation by the rotary drive device 7, and the soil inside is pushed out into the ground from the bottom end of the casing pipe 10. In this case, if the insertion length of the casing pipe 10 into the ground is approximately 1.4 m (2.6 m - 1.2 m) and the sewer pipe 152 is located approximately 3 m underground, the sewer pipe 152 will not be affected by the soil pushed out from the bottom end.

[0062] When dumping crushed stone 22 after at least the soil above ground level G inside casing pipe 10 has been pushed into the ground, lid 42 is opened. In this example, as described later, sewer pipe 152 is located at a depth of 3 m from ground level G, and lid 42 of extension casing pipe 10A is opened after casing pipes 10, 10A are inserted 3 m or more. However, since the opening / closing operations and rotation prevention operations of lid 42 of extension casing pipe 10A and casing pipe 10 are the same, the casing pipe 10 will be described as an example.

[0063] 4, in order to open and close the lid 42, the central divided frame portion 16C of the frame 15 is provided with mounting holes 54 for detachably mounting lock bolts 53 to be inserted into the slide holes 51 and the lid holes 52. Since the casing pipe 10 is positioned in the circumferential direction relative to the frame 15 by the rotation prevention means 31, the mounting holes 54 can be drilled in the frame 15 at positions corresponding to the slide holes 51 and the lid holes 52.

[0064] 4, after adjusting the height of the casing pipe 10 so that the height of the lid hole 52 matches the height of the mounting hole 54 of the frame 15, the lock bolt 53 is inserted into the mounting hole 54, slide hole 51, and lid hole 52, and the tip of the lock bolt 53 is screwed into the nut 53N. In addition, the bolt 58 of the closing and fixing means 57 is removed, and the fixation of the lid 42 is released.

[0065] Thereafter, the rotary drive device 7 is raised and the casing pipe 10 is lifted by the length of the slide hole 51, whereby the lock bolt 53 comes into contact with the lower edge of the long hole 32, opening the crushed stone inlet 21, and in this state, the lid body 42 is fixed by the opening and fixing means 55. The rotary drive device 7 fixed to the connecting lid 85 is raised by the lifting drive device 8, whereby the casing pipe 10 is lifted.

[0066] If there is no earth and sand inside the casing pipe 10 that will fall outside, the cover 42 can be opened when the casing pipe 10 has been inserted into the ground to a predetermined depth, i.e., when the upper end of the casing pipe 10, which is 2.6 m in this example, reaches the position of the frame 15. In this example, crushed stone 22 is introduced after the lower end of the casing pipe 10 reaches below the depth position of the sewer pipe 152, so the cover 42 of the casing pipe 10 is not opened and the casing pipe 10 is not locked, and the extension casing pipe 10A and the extension rod 9A are connected to continue excavation.

[0067] 10, a tip rod 9S is provided at the lower end of the rod 9, and a tip bit 81, which is a drilling bit having a sharp triangular pyramid shape toward the tip, is provided on the tip rod 9S, and the base end of the tip bit 81 is formed larger than the rod 9S. The tip rod 9S has a circular cross section.

[0068] A lower helical wing 82 serving as a tip-side helical wing is provided on the base end side of the tip bit 81 outside the casing pipe 10, and an upper helical wing 84 serving as a base-end helical wing is provided on the rod 9 with a gap 83 in the rod length direction from the lower helical wing 82. The gap 83 is a portion between the helical wings 82, 84 where there is no helical wing. The lower helical wing 82 and the upper helical wing 84 have the same helical direction, the lower helical wing 82 has a helical length of about 1 turn, and the upper helical wing 84 has a helical length of about 1.5 turns longer than the lower helical wing 82.

[0069] As shown in FIG. 10, the outer diameter of the lower helical impeller 82 is larger than the outer diameter of the casing pipe 10, and a ring-shaped abutment plate 88 that abuts against the lower end of the casing pipe 10 is fixed to its upper edge 82F. A plurality of stays 89 serving as vertical supports are provided in the circumferential direction between the lower surface of the abutment plate 88 and the upper surface of the lower helical impeller 82. The lower portion of the stay 89 is fixed to the upper surface of the lower helical impeller 82, and the upper portion is fixed to the lower surface of the abutment plate 88. The upper surface of the abutment plate 88 is an abutment portion that abuts against the lower end of the casing pipe 10. The width of the abutment plate 88, i.e., the difference between the radius of the outer peripheral edge and the radius of the inner peripheral edge, is about 25 to 45 mm. The abutment plate 88 is shown only in FIG. 10 and is omitted in other drawings.

[0070] As a result, when the rod 9 is pulled up, the abutment plate 88 as the abutting portion abuts against the lower end of the casing pipe 10, and the casing pipe 10 can be pulled up. Also, when the casing pipe 10 is not rotating and the rod 9 is pulled up while rotating, the upper surface of the abutment plate 88 slides against the lower end of the casing pipe 10, and the casing pipe 10 can be pulled up. Furthermore, the difference in radius between the outer peripheral edge and the inner peripheral edge is about 25 to 45 mm, and the central opening 88K of the abutment plate 88 is formed slightly smaller than the inner diameter of the casing pipe 10 and opens widely, so that the crushed stone 22 is smoothly sent downward. Also, since the outer diameter of the abutment plate 88 is smaller than the outer diameter of the lower spiral blade 82, the resistance during insertion can be reduced.

[0071] In addition, the upper spiral blade 84 has a smaller inner diameter than the casing pipe 10 and can be inserted into the casing pipe 10 and rotated.

[0072] A connecting lid 85 (Fig. 4) serving as a rotation transmission means can be connected to the casing pipes 10, 10A. This connecting lid 85 has a square insertion hole 86 (Fig. 5) through which the square rods 9, 9A, 9K are inserted. The connecting lid 85 is fixed to the rod lock 12 of the rotation drive device 7, and the rods 9, 9A, 9S, 9K are slidably inserted into the insertion hole 86.

[0073] Therefore, the rotation of the connecting lid 85 is transmitted to the rods 9, 9A, 9S, and 9K through the insertion holes 86, the connecting lid 85 and the rods 9, 9A, 9S, and 9K are rotated, and the connecting lid 85 is configured to be movable along the rods 9, 9A, 9S, and 9K. Since the connecting lid 85 is fixed to the rod lock 12 of the rotation drive device 7, the rotation drive device 7 and the connecting lid 85 can be moved along the rods when the rod lock 12 is released. In addition, a stopper 87 (FIG. 18) that engages with the rotation drive device 7 to prevent the base end rod 9K from slipping out downward can be provided at the base end of the base end rod 9K.

[0074] 18, when the connecting lid 85 is connected to the casing pipe 10 and the rods 9, 9A, 9S, 9K and the connecting lid 85 are rotationally driven by the rotation drive device 7, the casing pipe 10 rotates together with the rods 9, 9A, 9S, 9K. When the connection between the connecting lid 85 and the casing pipe 10 is released and the lock of the rod 9K by the rod lock 12 is released, the rotation drive device 7 and the connecting lid 85 become movable relative to the rods 9, 9K.

[0075] 4, a pair of connectors 71, 71 are provided on the underside of the connecting lid 85. As shown in FIG. 12, the connector 71 provided on the connecting lid 85 does not have the base end 72, and the upper surface of the tip end 73 is fixed to the underside of the connecting lid 85.

[0076] Then, the rods 9, 9A, 9S, 9K are lowered so that the connectors 71, 71 are positioned between the connecting receivers 61, 61 of the casing pipes 10, 10A as shown in Figure 11, and the lower surface of the connecting cover 85 abuts against the upper edge of the casing pipes 10, 10A.Then, as shown by arrow Z, the rods 9, 9A, 9S are rotated clockwise (drilling direction) so that the tip 73 of the connector 71 abuts against one side of the positioning abutment portion 63, the connecting cover 85 is connected to the casing pipes 10, 10A, and the casing pipes 10, 10A move up and down due to the up and down movement of the rods 9, 9A, 9S, 9K.

[0077] In this state, when the rods 9, 9A, 9S, 9K are rotated clockwise (drilling direction), the casing pipes 10, 10A also rotate clockwise (drilling direction) together, and when the rods 9, 9A, 9S, 9K are rotated counterclockwise (anti-drilling direction), the connection between the connector 71 and the connecting receiver 61 is released, and the connecting cover 85 can be removed by lifting the rods 9, 9A, 9S, 9K.

[0078] In order to make the connecting lid 85 and the casing pipes 10, 10A releasable in this manner, the bolts 65 are not used for fastening. The bolts 65 may be used for fastening and removed before removing the connecting lid 85. Similarly, when the casing pipes 10, 10A, 10A are to be rotated in only one direction, the bolts 65 may not be used for connecting the casing pipes 10, 10A, 10A to each other.

[0079] Similarly, when the lower surface of the connecting lid 85 is abutted against the upper edge of the casing pipe 10, 10A and then the rods 9, 9A, 9S are rotated counterclockwise (counter-drilling direction), the tip 73 of the connector 71 abuts against the other side of the positioning abutment portion 63, the connecting lid 85 is connected to the casing pipe 10, 10A, and the casing pipe 10, 10A moves up and down due to the up and down movement of the rods 9, 9A, 9S.

[0080] In this state, when the rods 9, 9A, 9S, 9K are rotated counterclockwise (counter-drilling direction), the casing pipes 10, 10A also rotate counterclockwise (counter-drilling direction) together, and on the other hand, when the rods 9, 9A, 9S, 9K are rotated clockwise (drilling direction), the connection between the connector 71 and the connecting receiver 61 is released, and the connecting cover 85 can be removed by lifting the rods 9, 9A, 9S, 9K.

[0081] 10, a male joint 91 is provided at the base end of the tip rod 9S, and a female joint 101 (FIG. 13) that is detachably connected to the male joint 91 is provided at the lower end of the rod 9. Also, a female joint 101 is provided at the upper end of the rod 9, female joints 101, 91 are provided above and below the extension rod 9A, and a male joint 91 is provided at the base end of the base end rod 9K.

[0082] 13, male joint 91 has an insertion portion 93 with a hexagonal cross section protruding from the tip surface of a square flange 92 toward the tip side, and the square flange 92 has the same shape as the outer shape of the rod, and two opposing side surfaces 94, 94 of the insertion portion 93 are provided with outer semicircular grooves 95 for engaging with a shear pin 100 in a direction intersecting the longitudinal direction of rod 9 and offset in the longitudinal direction. In addition, the base end of the tip rod 9S is fixed to the base end side of the flange 92 by a welded portion 96.

[0083] 13, the female joint 101 has an insertion receiving portion 103 for inserting the insertion portion 93 inside a square cylindrical portion 102 having the same shape as the outer shape of the rod, the insertion receiving portion 103 having an open tip and a hexagonal cross section, into which the insertion portion 93 is removably inserted. Inner semicircular grooves 105, 105 are formed on two opposing inner side surfaces 94, 94 of the insertion receiving portion 103 in correspondence with the outer semicircular groove 95, and both ends of the inner semicircular groove 105 communicate with through holes 105H, 105H penetrating the inside and outside of the cylindrical portion 102.

[0084] Furthermore, when the insertion portion 93 is inserted into the insertion receiving portion 103 and the tip surface of the cylindrical portion 102 abuts against the tip surface of the rectangular flange portion 92, a pin hole 100H into which the shear pin 100 is press-fitted is formed by the inner and outer semicircular groove portions 105, 95, and the male joint 91 and the female joint 101 are connected by pressing and fixing the shear pin 100 into the pair of pin holes 100H, 100H, while the connection between the male joint 91 and the female joint 101 can be released by removing the shear pin 100. The male joint 91 and the female joint 101 can be inserted into the insertion hole 86 of the connecting lid 85, and can move up and down while inserted.

[0085] Furthermore, when the rod 9 is connected to the tip rod 9S, the length between the upper edge 82F of the lower spiral blade 82 and the casing pipe 10 is longer than that of the casing pipe 10, for example by about 300 mm, and when the upper edge 82F of the lower spiral blade 82 is aligned with the tip edge of the casing pipe 10, the female joint 101 at the base end (upper end) of the rod 9 is positioned above the base end edge of the casing pipe 10, making it easy to connect an extension rod 9A to the upper end of the rod 9.

[0086] In addition, the length of the extension rod 9A including the male and female joints 91, 101 is the same as that of the extension casing pipe 10A, and as shown in Figure 17, the extension rod 9A is positioned so that the female joint 101 extends from the upper edge of the extension casing pipe 10A.

[0087] Then, as described above, when connecting the lower end of the first extension casing pipe 10A and the extension rod 9A to the upper ends of the casing pipe 10 and rod 9, as shown in FIG. 4, the casing pipe 10 is inserted until the upper end of the casing pipe 10 is at a height of, for example, 200 mm from the upper end of the anti-sway frame 13, and a casing pipe hoist (not shown) connected to the casing pipe 10A and a rod hoist 108 connected to the rod 9A are connected to the rotary drive device 7, as shown in FIG. 19, and the rotary drive device 7 is raised to hoist the casing pipe 10A and the rod 9A.

[0088] In this case, the rod 9A is placed inside the casing pipe 10A, and the rod 9A is lifted with the lower end side of the rod 9A projecting, for example, about 200 mm from the lower end of the casing pipe 10A. In this way, the male and female joints 101, 91 project from the ends of the casing pipes 10, 10A, making it easy to connect the male and female joints 101, 91.

[0089] In this way, the extension rod 9A is first connected to the upper end of the rod 9, and after this connection, the extension rod 9A will stand on its own even if the rod hanging device 108 is removed. Next, the connectors 71, 71 at the lower end of the extension casing pipe 10A are inserted into the upper edge of the casing pipe 10, and the connectors 71, 71 at the lower end of the extension casing pipe 10A are butted against the upper end of the casing pipe 10.

[0090] Next, the rotation drive unit 7 is lowered, and the insertion portion 93 of the male joint 91 at the lower end of the base end rod 9K is inserted into the female joint 91 at the upper end of the rod 9A, and they are connected by a shear pin 100. After this connection, the rotation drive unit 7 is lowered, the connecting lid 85 is placed over the upper edge of the casing pipe 10A, the connecting lid 85 is rotated by the rotation drive unit 7, and the connecting lid 85 is connected to the casing pipe 10A by the connecting means 60. Furthermore, the connecting lid 85 and the casing pipe 10A are angularly rotated by the rotation drive unit 7, and the connecting tool 71 of the upper casing pipe 10A is engaged with the connecting receiver 61 of the lower casing pipe 10, and further connected by the bolts 65, 68.

[0091] The connection of the lower end of the second extension casing pipe 10A and the extension rod 9A to the upper end of the first extension casing pipe 10A and the extension rod 9A, and the connection of the extension casing pipe 10A and the connecting cover 85 are also performed in the same manner. The extension casing pipe 10A and the extension rod 9A may be connected to the casing pipe 10 and the rod 9 after the upper end of the casing pipe 10 and the rod 9 are inserted into the ground below the anti-vibration frame 13 and close to the ground G. In this way, the long extension casing pipe 10A can be connected after the first casing pipe 10 is inserted deep into the ground.

[0092] 1, a hopper-shaped storage section 110 is provided on the vehicle body 2, and the crushed stone 22 is stored in this storage section 110. A belt conveyor 111 serving as a feeder is provided at the bottom of the storage section 110, and this belt conveyor 111 feeds the crushed stone 22 from the rear side to the front side. At the end of the belt conveyor 111, a feed path 112 serving as a chute is provided, and this feed path 112 is inclined so that the tip side is lower.

[0093] 14, at the end of the belt conveyor 111, a drop path 113 made of a pipe such as a steel pipe is vertically installed at the drop position of the crushed stone 22, the crushed stone 22 falls into this drop path 113, and the base end of the input path 112 is located at the lower end of the drop path 113. A flange portion 113F is provided at the upper edge of the drop path 113, and this flange portion 113F is connected to a flange-shaped rotating slide plate 114 rotatably provided on the vehicle body 2, whereby the drop path 113 is rotatably provided on the vehicle body 2.

[0094] As shown in Figs. 14 to 16, the throw-in path 112 has a bottom surface portion 115 and left and right side portions 116, 116 rising from the left and right sides of the bottom surface portion 115. At the base end side of the upper edge of the left and right side portions 116, 116, connecting holes 116H, 116H as connecting portions are drilled. With the left and right connecting holes 116H, 116H sandwiching the outer periphery of the fall path 113, the connecting holes 116H and the fall path 113 are connected by a pivot 117, and the throw-in path 112 is connected to the fall path 113 so as to be swingable around the left and right pivots 117, 117, so that the front side of the throw-in path 112 can swing up and down. In addition, the throw-in path 112 can be fixed at a desired inclination angle by a fixing means (not shown) with the inclination angle adjusted. In addition, as an example, the fall path 113 has a diameter of about 400 mm and a height of about 200 mm.

[0095] The left and right width of the input path 112 is larger than the diameter of the casing pipes 10, 10A, and the left and right width of the crushed stone input port 21 is narrower than this diameter, so the bottom surface tip 115S, which is the tip side of the bottom surface part 115, is formed so as to narrow toward the tip, and the left and right width of the tip of the bottom surface tip 115S corresponds to the left and right width of the crushed stone input port 21. In addition, the left and right side surface tips 116S, 116S of the left and right side surface parts 116, 116 are formed lower than the base end side, and the interval between the left and right side surface tips 116S, 116S corresponding to the bottom surface tip 115S is configured so as to narrow toward the tip.

[0096] In addition, a flexible hair bottom part 120 is provided at the tip of the bottom part 115, and an attachment part 121 is provided on the lower surface of the bottom part 120, and this attachment part 121 is provided so that it can move back and forth and be fixed at a moving position relative to the bottom part 115. The base end side of the hair 122 is fixed to the attachment part 121, and the tip of the hair 122 protruding from the tip of the bottom part 120 is made a free end, and a plurality of hairs 122 are densely arranged in a line in the width direction of the bottom part 115 and have a part protruding from the tip of the bottom part 115. The belt conveyor 111, the input path 112, and the drop path 113 form an input device 118 that inputs crushed stone 22.

[0097] Flexible hair side sections 123, 123 are provided on the outer surfaces of the left and right side sections 116, 116, and the hair side sections 123 are provided with attachment sections 124 on the outer surfaces of the side sections 116, and the attachment sections 124 are larger in height than the side end sections 116S, and a plurality of hairs 122 are planted in the attachment sections 124 so as to be lined up closely in the height direction of the side sections 116, and the tips of the hairs 122 protruding from the tips of the side sections 116 are free ends. The attachment sections 124 are provided so as to be movable back and forth relative to the side sections 116 and to be fixed in position at the moved position.

[0098] The hair 122 is made of a thermoplastic resin such as polypropylene, polyvinyl chloride, nylon, etc., and has a substantially circular cross section and a rod shape with a diameter of, for example, about 2 to 3 mm. The left and right hair side portions 123, 123 of the hair bottom portion 120 constitute the input path tip portion 113S made of the hair 122.

[0099] The interval between the left and right hair side parts 123, 123 is narrowed toward the tip side. For example, if the crushed stone inlet 21 has a left-right width W of 120 mm and a height of 100 mm, the left-right interval K of the tips of the hair side parts 123, 123 is narrower, about 80 to 100 mm, and the interval K is 0.6 to 0.9 times the left-right width W, and the tips of the left and right hair side parts 123, 123 are arranged so that they can be inserted into the crushed stone inlet 21. The interval K of the tip part of the hair bottom part 120 sandwiched between the left and right hair side parts 123, 123 is also approximately the same as the interval K. That is, as shown in FIG. 16(B), the interval K is the interval between the hairs 122, 122 located inside the tips of the hair side parts 123, 123.

[0100] The hair bottom portion 120 and the hair side portions 123, 123 have a length that allows the tip of the hair 122 to abut against the outer surface of the casing pipe 10, 10A, and the abutment occurs by moving back and forth and fixing.When the casing pipe 10, 10A descends, the tip abuts against the outer surface of the casing pipe 10, 10A and the hair 122 elastically deforms.When it reaches the position of the inlet 21, the tip of the hair 122 penetrates inside through the inlet 21, and the flexible inlet path tip portion 113S has excellent shape recovery, water resistance and abrasion resistance, allowing for smooth injecting of crushed stone.

[0101] In addition, the left and right hair side portions 123, 123 of the hair bottom portion 120 are broom-shaped and bundle the base ends of the multiple hairs 122 together, with the tip ends of the hairs 122 spread out. As a result, there are gaps between the hairs 122 at the tip side, and some of the soil and sand other than the crushed stone 22 falls from the tip end 113S of the input path at the tip side, thereby preventing soil and sand from entering the casing pipes 10, 10A.

[0102] As shown in Fig. 1, the ground improvement device 1 is equipped with an automatic material transport device 131. This material transport device 131 has a vehicle body 132, which is a self-propelled vehicle, with caterpillar tracks 133 as a traveling means under it, and this caterpillar track 133 is driven by a prime mover (not shown) mounted on the vehicle body 132. A driver's cab 134 is provided at the front of the vehicle body 132, and a loading platform 135 is provided at the rear of the vehicle body 132, and this loading platform 135 is tiltable so that the front side moves up and down around a pivot 136 at the rear of the loading platform 135, and is tilted and driven by the prime mover or the like. The traveling means may be tires instead of caterpillar tracks.

[0103] A hoist 141 is mounted at the rear of the cab 134 and in the left-right center of the vehicle body 132. This hoist 141 includes a vertical arm 142, a rotation drive means (not shown) for driving the vertical arm 142 to be rotatable about a vertical axis relative to the vehicle body 132, a tilting arm 144 that is rotatably connected to the upper end of the vertical arm 142 and tilts so that the tip side moves up and down by a tilting drive means 143 such as a fluid pressure cylinder, and a tip arm 145 that is rotatably suspended from the tip of the tilting arm 144. The tilting arm 144 is driven to extend and retract by a fluid pressure cylinder (not shown) serving as an extension and retraction means.

[0104] A clamshell bucket 147 serving as a crushed stone scraping means is provided at the lower end of the distal arm 145. This clamshell bucket 147 includes a pair of shells 148, 148 that rotate between a closed position and an open position, and an opening / closing drive means 149 that opens and closes these shells 148, 148.

[0105] As shown in Figures 1 and 2, at the construction site, a sewer pipe 152, which is a sewer pipeline, is installed between manholes 151, 151, which are sewer pipelines, and crushed stone piles 153 for the sewer pipe are installed in a staggered pattern so as to sandwich the sewer pipe 152, and crushed stone piles 153A for manholes are installed in four locations surrounding the manhole 151.

[0106] For example, if the construction methods of the conventional technology are applied as they are to construction such as ground improvement work for an existing manhole 151, the horizontal expansion of the pressed crushed stone 22 will generate lateral earth pressure on the sewer pipe 152, which may cause horizontal displacement or partial pressurization of the manhole 151 and hollow underground buried objects such as pipelines and septic tanks (not shown), resulting in damage.

[0107] In response to this, in this embodiment, a technology was invented that utilizes the internal cavity of the casing pipes 10, 10A to prevent lateral earth pressure load from being applied to buried objects such as the sewer pipe 152. In the process of pressing in the casing pipes 10, 10A for excavation, in hard ground where lateral earth pressure is likely to occur, the spiral blades 82, 84 installed at the bottom end of the casing pipe 10 are rotated forward (in the excavation direction) to take in soil particles equivalent to the volume of the casing pipe 10, 10A inserted into the ground into the casing pipe 10, 10A, preventing lateral earth pressure from being generated on the ground at the bottom end of the casing pipe 10.

[0108] In addition, when the soil particles taken into the casing pipes 10, 10A reach the soft layer, they are discharged from the bottom end of the casing pipe 10 by the reverse rotation (rotation in the direction opposite to the excavation direction) of the spiral blades 82, 84, and consolidated against the soft layer wall where lateral earth pressure is not generated. If there is residual soil in the casing pipes 10, 10A, all the residual soil is discharged from the bottom end of the casing pipe 10 at the bottom end of the excavation where it is not affected by the earth pressure of the buried object. In addition, the hardness of the on-site ground is visually controlled by the ground reaction force and the rotation torque value of the spiral blades 82, 84 displayed in real time on the construction management device monitor during construction. The ground reaction force acting on the spiral blades 82, 84 is an upward force acting on the rod, and is obtained from the load of the motor of the lifting drive device 8, etc.

[0109] Next, a construction example of a liquefaction prevention method, which is a ground improvement method using the ground improvement device 1, will be specifically described with reference to Figs. 20 to 25. The construction of an existing hollow underground buried object will be described below, but it can also be used for construction of a new object. The vehicle body 2 is moved to the construction position, the leader 5 is aligned with the construction position, and the axis of the rod 9 is aligned with the position of the drilling hole 161. In addition, the tip height of the tip bit 81 protruding from the tip of the casing pipe 10 is adjusted to the ground surface G, and preparations are made before excavation.

[0110] Before starting excavation of the ground below the ground surface G, the connecting lid 85 is connected to the upper end of the casing pipe 10, and the crushed stone inlet 21 is closed by the lid 42. If the casing pipe 10 is inserted into the ground with the crushed stone inlet 21 open, there is a risk that the soil in the casing will overflow from the crushed stone inlet 21 above ground, but by closing the crushed stone inlet 21, the leakage of soil can be prevented, and also, if the groundwater level is high and depending on the soil type, there is a risk that soil from the hole wall will enter during insertion, but it is possible to prevent soil from entering the crushed stone inlet 21 from the outside underground.

[0111] During insertion, the rod 9 and the casing pipe 10 are repeatedly moved up and down in the direction opposite to the excavation rotation, and, if necessary, the rod 9 and the casing pipe 10 are rotated in the excavation direction of the helical blades 82, 84 while applying a downward force to the rotary drive device 7 by the lift drive device 8 to insert the casing pipe 10, and the lower end of the casing pipe 10 is inserted to the design depth. In addition, in soft ground, except for the rotation in the direction opposite to the excavation direction to discharge the soil inside, the borehole 161 may be formed by rotation in the excavation direction from the start of excavation until the design depth is reached.

[0112] In this case, the design depth is deeper than the buried position of the corresponding underground structure, for example, the sewer pipe 152, and is the depth at which the lateral earth pressure generated by discharging the soil or crushed stone 22 from the casing pipe 10 by rotating the rod 9 in the direction opposite to excavation does not affect the underground structure. Also, the design depth is generally located on soft ground.

[0113] For example, if the sewer pipe 152 has a diameter of approximately 600 m, and soil or crushed stone 22 is discharged from the tip of the casing pipe 10 within a height range of 600 mm, it will be affected by lateral earth pressure, so construction is carried out so that lateral earth pressure is not applied within the height range above that range, or for safety reasons, within a height range of 1000 mm (hereinafter referred to as the lateral earth pressure influence range H), and the design depth is set below that height range. As shown in Figure 1, if the lateral earth pressure influence range H is 1000 mm, the lateral earth pressure influence range H will be between a depth H1 of 500 mm above the center of the sewer pipe 152 at the top and a depth H2 of 500 mm below the center of the sewer pipe 152 at the bottom. The design depth will be below the depth H2.

[0114] When the helical blades 82, 84 are rotated in the excavation direction to form a borehole 161, as shown in Fig. 20, crushed stone 22 is filled in the gap 83 between the lower helical blade 82 and the upper helical blade 84 inside the casing pipe 10, and the ground is excavated while rotating the rod 9 in the excavation direction to loosen the ground and form a borehole 161. When the lower helical blade 82 is rotated in the excavation direction in this manner, the rotation of the lower helical blade 82 in the excavation direction moves the excavated soil upward and tries to enter the casing pipe 10, but the crushed stone 22 in the gap 83 acts as a lid for the lower end of the casing pipe 10, suppressing the intrusion of the excavated soil, thereby preventing the excavated soil from rising.

[0115] In addition, the results of the experiment showed that by setting the height of the gap 83 to 10 cm in soft ground and to about 30 cm in hard ground, it was possible to prevent the excavated soil from rising into the casing pipe 10. As a result, it was found that it was necessary to set the gap 83 larger in hard ground than in soft ground.

[0116] Also, since there is a risk of the crushed stone 22 being fed from above becoming clogged, the upper helical blade 84 may have 1 to 1.5 turns. And, in order to drop the crushed stone 22 into the gap 83 by rotating in the direction opposite to excavation, the upper helical blade 84 needs at least 1 turn. With 1.5 turns, the crushed stone 22 from above is likely to become clogged. The lower helical blade 82 for excavation has 2 turns.

[0117] Furthermore, when the casing pipe 10 is inserted with rotation in the excavation direction, even if the gap 83 is filled with crushed stone 22, soil may rise up into the casing pipe 10A, so the rotation may be switched to the counter-excavation direction to discharge the soil inside from the tip of the casing pipe 10. In this example, the rotation of the spiral blades 82, 84 in the counter-excavation direction is counterclockwise as viewed from above, as shown by the arrow Y in Figure 8.

[0118] As shown in Fig. 21, when the lower end of the casing pipe 10 reaches the soft ground at the design depth by rotating the casing pipe 10 and the rod 9 in the excavation direction, the injection of crushed stone is started. Note that Fig. 20 and Fig. 23 show an example in which the design depth is reached by one casing pipe 10, but as described above, one or more extension casing pipes 10A and rods 9A are used in conjunction.

[0119] After drilling the borehole 161 to the designed depth and the lower spiral blade 82 reaching the soft ground, the rod 9, which is rotated in conjunction with the casing pipe 10, is rotated in the counter-drilling direction while repeating up and down movements, and the casing pipe 10 is inserted into the ground while compacting the original ground to the external volume of the pipe.

[0120] Furthermore, until the lower end of the casing pipe 10 reaches the design depth, only the gap 83 in the casing pipe 10 is filled with crushed stone 22, and no additional crushed stone 22 is added.

[0121] By repeatedly moving the rod 9 and the casing pipe 10 up and down in the direction opposite to the drilling rotation, and by performing loosening and stirring operations in the drilling rotation direction of the rod 9 and the casing pipe 10 as necessary, when the specified drilling depth (design depth) is reached, as shown in Figure 21, the connecting cover 85 is removed from the casing pipe 10.

[0122] This will be described using the casing pipe 10 as an example with reference to Figure 18. In Figure 18(A), when the rod 9K is rotated in the clockwise direction, which is the excavation direction, with the connecting cover 85 connected to the casing pipe 10, the rod 9K and the casing pipe 10 rotate together.

[0123] From here, if there is no connection by the bolt 65, when the connecting lid 85 is rotated counterclockwise, the connecting device 71 comes off the connecting receiver 61, and when the rod lock 12 is unlocked, the lifting drive device 8 can lift the rotation drive device 7 along the rod as shown in Figure 18 (B), and the connecting lid 85 comes off the casing pipe 10.

[0124] In this way, the rotation of the casing pipe 10 is stopped and only the rod 9 is rotated counterclockwise, and the upper helical blade 84 in the casing pipe 10 discharges the excavated soil into the ground from the lower end of the casing pipe 10, thereby securing a columnar cylindrical space for introducing crushed stone in the casing pipe 10. In addition, the diameter and length of the casing pipes 10, 10A can be changed depending on the performance required for the columnar crushed stone piles 153, 153A.

[0125] The upper spiral blade 84 inside the casing pipe 10 discharges the excavated soil inside the casing pipe 10 into the ground, and after a columnar cylindrical space for introducing crushed stone has been secured inside the casing pipe 10, the crushed stone inlet 21 is opened, and the casing pipes 10, 10A located in the anti-vibration frame 13 are prevented from rotating by the anti-rotation means 31. Crushed stone 22 is introduced through the crushed stone inlet 21, and the rod 9 is rotated in the anti-excavation direction (counterclockwise).

[0126] Furthermore, the casing pipe 10 in the rotation-prevented state is released from its connection with the connecting cover 85, and to lift up the casing pipe 10, as shown in Figure 10, when the rod 9 is pulled up, the abutment plate 88 fixed to the upper edge 82F position of the lower spiral blade 82 abuts against the lower edge of the casing pipe 10, so that the casing pipe 10 can be lifted up by pulling up the rod 9.

[0127] The crushed stone 22 supplied into the casing pipe 10 is deposited at the bottom of the borehole 161 by the upper helical blade 84 and the lower helical blade 82 rotating in the counter-excavation direction, as shown in Fig. 22. After the connecting cover 85 is removed from the casing pipe 10, the crushed stone 22 is compacted by the rotating rod 9. The rod 9 rotating in the counter-excavation direction is moved up and down against the crushed stone 22 deposited at the bottom of the borehole 161, and the lower helical blade 82 and the tip bit 81 are driven into the deposited crushed stone 22 with a set pressure, and the deposited crushed stone 22 is spread horizontally. After that, the tip bit 81 is temporarily pulled out of the deposited crushed stone 22, and the crushed stone 22 is further added into the spread gap.

[0128] The thrusting is performed multiple times, and the piled crushed stones 22 are pushed horizontally and further crushed stones 22 are added into the expanded gap, and this rolling compaction is repeated until the set compression force is supported. That is, by pushing the piled crushed stones 22 horizontally, as shown in Fig. 23, the upper surface position of the piled crushed stones 22 is lower than before thrusting, and between the upper surface position and the lower end of the casing pipe 10, there is soil in the ground, but there is no crushed stone 22 or the density of the crushed stone 22 is smaller than that of the lower part, and a portion (the expanded gap) where additional supply is possible is formed, and the crushed stones 22 are additionally supplied to the portion where additional supply is possible by the spiral blades 82, 84 as an additional supply operation in the rolling compaction operation, and the thrusting operation is performed, and the rolling compaction is repeated until the set compression force is supported.

[0129] By measuring the reaction force applied to the rod 9 during thrusting, after confirming that the set pressure input (bearing force) is secured, the rod 9 is rotated leftward in the same position and the crushed stone 22 is poured in. Since the crushed stone mass at the bottom is already compacted and has a bearing capacity, the crushed stone 22 starts to expand horizontally due to the left rotation pressure of the lower spiral blade 82. The crushed stone 22 expanded by the intermittent pouring of the crushed stone 22 and the rotation of the lower spiral blade 82 consolidates the original ground soil particles in the horizontal direction, and eventually the rotation torque of the motor as the driving means of the rotary drive device 7 reaches the pushing resistance reaction force that satisfies the set rotation torque, and the crushed stone 22 is expanded at the bottom of the borehole 161, and the consolidated crushed stone 22 having a predetermined bearing capacity expands in the circumferential direction of the borehole 161. The consolidated crushed stone 22 expands in the circumferential direction of the borehole 161, and a bulb-shaped consolidated crushed stone portion 154 is formed (formation of consolidated crushed stone portion). Depending on the conditions of the site, crushed stone piles 153, 153A without the crushed stone compaction portion 154 may be installed.

[0130] When the rotational torque reaches a set value, the casing pipe 10 and the rod 9 are raised to a predetermined height of about 10 cm, and the work of constructing the columnar crushed stone pile 153, which is a consolidated pile, begins.

[0131] After the above-mentioned compacted portion is formed, as shown in Fig. 24, the rod 9, which has its axial positional relationship locked, is placed on the crushed stone compacted portion 154, and the lower spiral blade 82 and the tip bit 81 protrude from the lower part of the casing pipe 10 with the rod 9 inside, and the rod 9 repeats the crushed stone input and up and down repeated compaction with the compaction pressure input and the rotation torque that are numerically set in advance, thereby forming a columnar crushed stone pile 153, 153A with external dimensions suitable for the soft ground environment up to the height of the ground G (Fig. 25). At this time, the magnitude of the internal friction angle (e.g. 30 degrees or more) of the crushed stone 22 can be used to promote the consolidation of soil particles in the original ground. In addition, the crushed stone pile 153, 153A is constructed by, for example, pulling up the casing pipe 10 and the rod 9 to a predetermined height of about 10 cm (centimeters) (pulling up to a predetermined height), discharging additional crushed stone 22 into the ground, and repeating up and down movement in the counter-excavation direction (adding crushed stone, up and down movement in the counter-excavation direction) to construct the crushed stone pile 153, 153A to the predetermined height using the crushed stone 22 (construction of the crushed stone pile to the predetermined height), and then pulling up the casing pipe 10 and the rod 9 again to the predetermined height (pulling up to a predetermined height), discharging additional crushed stone 22 into the ground, and repeating up and down movement in the counter-excavation direction (adding crushed stone, up and down movement in the counter-excavation direction). In this way, the crushed stone 22 is discharged from the casing pipe 10 into the borehole 161 at each predetermined height, and the discharged crushed stone 22 is repeatedly consolidated, whereby the crushed stone pile 153, 153A of the designed height is constructed (construction of the crushed stone pile completed).

[0132] However, the discharge of soil and crushed stone 22 from the lower end of the casing pipe 10 and the compaction of the crushed stone 22 discharged from the lower end using the rod 9 are not carried out in the lateral earth pressure influence range H, or the load applied to the crushed stone 22 is lowered than in other parts, so that a large lateral load is not applied to the hollow underground structure. Also, the lateral earth pressure range of the crushed stone pile 153A for a manhole is from the ground G to below the bottom surface 151T of the manhole 151, and the entire length of the crushed stone pile 153A may be constructed without compacting.

[0133] Incidentally, using crushed stone 22 with a large internal friction angle is advantageous for compacting the ground, but if crushed stone 22 with an internal friction angle of 30 degrees or more is used, the crushed stone 22 supplied into the casing pipe 10 will harden within the casing pipe 10, and the crushed stone 22 will rotate together with the rod 9 and the casing pipe 10 while remaining solid, making it impossible to drop and supply it into the borehole 161. In this case, if the connection between the casing pipe 10 and the connecting cover 85 is released and the rod 9 is rotated counterclockwise while the casing pipe 10 is not rotating, the crushed stone 22 on the tip side of the casing pipe 10 will be agitated by the upper spiral blade 84, and the crushed stone 22 will be able to be supplied into the borehole 161 from the tip of the casing pipe 10.

[0134] In addition, as known liquefaction countermeasures, there are ground compaction, solidification (solidifying the entire ground), replacement (replacing soil), lowering the groundwater level (artificially lowering the groundwater level), pore water dissipation (absorbing water pressure with sand piles or crushed stone piles), and increasing shear resistance (resisting external forces), but all of these are large-scale construction methods using large machinery, and it is practically impossible or difficult to use them as liquefaction countermeasures for detached house ground. In contrast, in this embodiment, by adopting the above-mentioned construction method, it is possible to construct a ground that is seismically isolated and liquefaction-resistant for the entire construction area by incorporating ground compaction, replacement, soil particle pore water pressure dissipation, and shear resistance strengthening into the construction process and creating a complex synergistic effect. This construction method allows the selection of construction machines of a size according to the construction scale of the liquefaction prevention construction, and is a disaster prevention technology that makes it possible to miniaturize construction machines as a result of incorporating the advantages of each type of construction into the construction method and improving the suppression performance through the synergistic effect of seismic isolation and liquefaction.

[0135] In this embodiment, in accordance with claim 1, a rod 9 rotated by a rotary drive device 7 and inserted into the ground, and a casing pipe 10 fitted around the rod 9, with a crushed stone inlet 21 on its outer periphery, and inserted into the ground are used, and a borehole 161 is formed below the sewer pipe 152, which is a sewer pipeline, using the rod 9 and the casing pipe 10, and a borehole 161 is also formed below the manhole 151, which is a sewer pipeline, using the rod 9 and the casing pipe 10, and crushed stone 22 is poured into this borehole 161 to construct a crushed stone pile 153. Therefore, by pouring crushed stone 22 into the borehole 161 formed below the sewer pipe 152, a crushed stone pile 153 is constructed from the ground G to below the sewer pipe 152, which makes it possible to prevent liquefaction, and the casing pipe 10 can be used to perform construction so that a large lateral earth pressure is not applied to the sewer pipe 152.

[0136] In this manner, in this embodiment, in accordance with claim 2, construction is performed on the sewer pipe 152, which is an existing sewer pipeline, while it is in use, so that there is no need to stop the use of the sewer pipe 152 before construction.

[0137] In this manner, in this embodiment, corresponding to claim 3, after the lower parts of the casing pipe 10 and the rod 9 are inserted into the ground, the connection between the rod 9 and the rotary drive unit 7 is released, the rotary drive unit 7 is moved upward, and below the rotary drive unit 7, the lower end of the extension casing pipe 10A and the lower end of the extension rod 9A are connected to the upper end of the casing pipe 10 and the upper end of the rod 9. Therefore, by inserting the casing pipe 10 and the rod 9 into the ground, and then adding the extension casing pipe 10A and the extension rod 9A to the casing pipe 10 and the rod 9, construction can be carried out while reducing the overall height dimension of the device.

[0138] In this manner, in this embodiment, which corresponds to claim 4, in the device used in the liquefaction prevention method for sewer pipes and underground buried objects described in claim 1, a vehicle body 132 which is a self-propelled vehicle is provided with a loading platform 135 for loading crushed stone 22 and a hoist 141 which is a loading / unloading device for loading and unloading the crushed stone 22 onto this loading platform 135. Therefore, the crushed stone 22 can be supplied by the vehicle body 132 equipped with the hoist 141 and loading platform 135, making it possible to carry out continuous construction work, and at the same time reducing the number of times of travel back and forth between the crushed stone yard and the construction site.

[0139] In this manner, in this embodiment, which corresponds to claim 5, in an apparatus used in the liquefaction prevention method for sewerage pipelines and underground buried objects described in claim 1, a feed path 112 for feeding crushed stone 22 into the crushed stone inlet 21 is provided, and this feed path 112 is provided with a flexible feed path tip 112S, so that the flexible feed path tip 112S can be brought into contact with the outer surface of the casing pipe 10, allowing the crushed stone 22 to be smoothly fed into the crushed stone inlet 21.

[0140] In this manner, in this embodiment, corresponding to claim 6, in the device used in the liquefaction prevention method for sewer pipelines and underground buried objects described in claim 1, an opening / closing means 41 for opening and closing multiple crushed stone inlets 21 is provided. Therefore, by closing the crushed stone inlets 21, it is possible to prevent internal soil and sand from leaking from the crushed stone inlet 21 on the aboveground when the casing pipe 10 is inserted into the ground, and it is also possible to prevent soil and sand from underground from entering the casing pipe 10 through the crushed stone inlet 21 when the groundwater level is high, for example.

[0141] According to claim 1, when the conventional construction method is applied to an existing sewer pipe as it is, the horizontal expansion of the crushed stone 22 generates lateral earth pressure, which may cause horizontal movement or partial pressurization of hollow underground objects such as the sewer manhole 151, the sewer pipe 152 as a pipe, and the septic tank. In contrast, the present invention uses the casing pipe 10 to construct crushed stone piles 153, 153A for preventing liquefaction around the underground objects with almost no soil removal while maintaining the current bearing capacity of the underground objects. The present invention is a construction method that uses the hollow shape of the casing pipe 10 made of steel pipes or the like to absorb horizontal displacement and damage caused by lateral earth pressure of underground objects that occurs during existing (including new) liquefaction countermeasure construction.

[0142] As a conventional method for preventing liquefaction of underground buried objects according to claim 2, for example, techniques such as internal processing and outer periphery gravity processing have been disclosed for the manhole 151 itself. This technique is carried out by stopping the supply of sewerage, and is not practical for earthquake resistance of existing sewerage. The present invention is a technique for preventing liquefaction without contacting underground buried objects such as sewerage facilities, and adopts a method of construction in which existing underground buried objects are in operation. Therefore, while the sewerage facility is in operation, crushed stone piles 153, 153A can be driven from the bottom of the buried objects to the ground G at the four corners of the manhole 151 and the left and right longitudinal directions of the sewer pipe 152 without contacting the buried objects, thereby preventing liquefaction.

[0143] In the case of claim 3, there is a problem of temporary detouring of overhead crossing lines in liquefaction countermeasure construction of sewerage pipes and underground buried objects in urban areas. In this embodiment, construction can be performed within a maximum height of 4.5 m above ground, and detouring overhead crossing lines such as electric wires is not necessary, and a long crushed stone pile that is larger than the dimensions of the overhead obstacles can be constructed. As an example, the height of the leader 5 of the construction machine body is 4.3 m above ground. Normally, the construction length in this case is about 3.1 m, but when the bottom end of the leader stroke is reached due to the gripping and changing function of the rods 9 and 9A, the joint lock by the two shear pins 100 is released, only the short base end rod 9K and the rotary drive device 7 are raised, and the extension rod 9A contained in the extension casing pipe 10A is connected to the rod 9 and pressed in again, making it possible to construct up to a maximum length of 6.1 m. Therefore, there is no need to detouring or remove overhead obstacles. In addition, for construction without overhead obstacles, a single rod machine device can be used without intermediate connections.

[0144] In the past, crushed stone 22 used as material was stored in a temporary crushed stone storage area and had to be transported in small quantities by backhoe several times when used. In the case of linear construction such as road construction, the construction progress rate is fast and small-scale transportation from the yard is not realistic in terms of traffic safety management and construction cycle time. In contrast, a self-propelled device equipped with a loading platform 135 and a hoist 141 as a loading and unloading device is used as the material transporting device 131. This is a self-propelled small-scale material transporting device equipped with a clamshell 147 for loading and unloading materials and a loading platform 135. In the smooth construction of crushed stone piles to prevent liquefaction, the efficient construction depends on the prompt supply of materials. Therefore, a self-propelled transporting device equipped with a clamshell 147 for loading and unloading materials and a loading platform 135 is used. A large amount of crushed stone 22 is loaded from the temporary crushed stone storage area in the attached clamshell 147, transported by self-propelling, and transferred to the storage section 110, which is a crushed stone hopper attached to the construction machine body, by the clamshell 147. This makes it possible to carry out continuous construction work, and at the same time, by using the clamshell 147, which is larger than the bucket of a backhoe, the number of round trips required to use a backhoe is drastically reduced from five to one, reducing the risk of passing through urban areas and enabling significant savings in direct and indirect costs such as labor and oil and grease.

[0145] In the case of claim 5, when crushed stones 22 are fed into the iron casing pipes 10, 10A that are constantly swinging up and down using the feed path 112 made of iron, which is an iron chute, mutual buffering may prevent smooth feeding of crushed stones. In response to this, a method of feeding crushed stones 22 into the casing pipes 10, 10A made of hard material using the feed path 112 made of hard material is to use a bundle of long-haired "broom"-shaped hairs 122 as buffer material.

[0146] According to claim 6, all crushed stone inlets 21 of the casing pipes 10, 10A are provided with lids 42 as opening and closing covers. This allows all crushed stone inlets 21 of the casing pipes 10, 10A to be opened and closed as desired. In order to prevent the soil stored in the casing pipes 10, 10A from overflowing from the crushed stone inlets 21 in a "loose soil" state when the casing pipes 10, 10A are inserted into hard ground, the casing pipes 10, 10A are provided with a plurality of crushed stone inlets 21 and closing sections 44 alternately arranged at equal intervals in a straight line in the axial direction. The crushed stone inlet 21 and the closing section 44 of the casing pipes 10 and 10A are arranged in the same position as the crushed stone inlet 21 inside the casing pipe 10, and a cover 42, which is a back cover iron plate that can slide up and down, is attached. Also, to prevent the cover 42 from falling off up, down, left and right, rails 45, 45 consisting of L-shaped angles on the left and right in the longitudinal direction and at the bottom end and a support member 46 are welded to the inner surface inside the casing pipes 10 and 10A. Also, a cover hole 52 is provided at the top end of the cover 42, into which a lock bolt 53 acting as a lock pin is inserted from the outside to attach the cover 42 to the casing pipes 10 and 10A. An elliptical slide hole 51 is provided in the casing pipes 10 and 10A at the same position as the cover hole 52 so that the cover 42 can slide up and down. The crushed stone inlet 21 can be opened and closed by inserting a rod-shaped member 34 into the anti-rotation hole 33 and the lid hole 52 through the anti-rotation hole 33 provided in the anti-sway frame 13 of the vehicle body 2, and operating the up and down movement of the casing pipe 10. As a modified example of the opening and fixing means 55 and the closing and fixing means 57, the female screw holes 55M, 57M may be made into through holes, and the bolts 56, 58 inserted into these through holes may be tightened and locked into nuts (not shown) provided on the inner surface of the lid 42.

[0147] As an effect of the embodiment, since the casing pipes 10, 10A are provided with the rotation prevention means 31, the crushed stones 22 can be charged with the multiple crushed stone inlets 21 in a constant direction. Also, the rotation prevention means 31 has the long holes 32 that are continuous in the length direction in the casing pipes 10, 10A, but the reinforcing members 40 can prevent the long holes 32 from expanding in the width direction.

[0148] The cover 42 is wider than the width of the crushed stone inlet 21, has a communicating opening 43 that is the same shape as the crushed stone inlet 21 and communicates with the crushed stone inlet 21, and has a blocking portion 44 that can block the crushed stone inlet 21 between the vertically adjacent communicating openings 43, 43, so that the cover 42 can simultaneously open and close a plurality of crushed stone inlets 21. Furthermore, the upper portion of the casing pipes 10, 10A is provided with a slide hole 51 that is a long hole in the length direction, and the cover 42 is provided with a cover hole 52 corresponding to the slide hole 51. A lock bolt 53 that is a pin-shaped operating body is inserted into the slide hole 51 and the cover hole 52, the lock bolt 53 is fixed to the frame 15 that is the fixing portion, and the casing pipes 10, 10A are raised by the amount of the slide hole 51, so that the cover 42 can be opened and closed reliably.

[0149] Furthermore, the pipe connecting means 60 has a connecting receiver 61 provided on the inner surface of the upper part of the lower casing pipe 10, and a connecting device 71 that connects to the connecting receiver 61 is provided at the lower end of the upper casing pipe 10A, so that the casing pipe 10A can be connected in both clockwise and counterclockwise directions. Also, since the through holes 62T are drilled on both the left and right sides of the positioning abutment portion 63, the upper casing pipe 10A can be turned either counterclockwise or clockwise to engage the locking recesses 74 with the locking projections 62, and then fixed with the bolts 65, which are connecting and fixing means.

[0150] In addition, since the connecting lid 85 is integrally provided with the rotary drive device 7, the connecting lid 85 and the rotary drive device 7 can be connected and disconnected to the upper end of the casing pipe 10, 10A by rotating the connecting lid 85 by the rotary drive device 7, and in the connected state, the casing pipe 10, 10A can be moved up and down by raising and lowering the rotary drive device 7 by the lifting drive device 8. Furthermore, in the connected state, if the rod lock 12 is released from the lock, only the rod 9 can be moved up and down, and crushed stone compaction can be performed by the up and down movement of the rod 9. On the other hand, if the connected state is released, the casing pipe 10, 10A can be moved up and down while the rod 9 is rotating without rotating.

[0151] Furthermore, the outer diameter of the lower spiral blade 82 is formed to be larger than the outer diameter of the casing pipe 10, and a ring-shaped abutment plate 88 that abuts against the lower end of the casing pipe 10 is fixed to its upper edge 82F. Therefore, when the rod 9 is pulled up, the abutment plate 88, which serves as the abutment part, abuts against the lower end of the casing pipe 10, and the casing pipe 10 can be pulled up.

[0152] The pair of connectors 71, 71 are provided on the underside of the connecting lid 85, so that the connecting lid 85 can be connected to and disconnected from the upper ends of the casing pipes 10, 10A.

[0153] In addition, the input path 112 for inputting the crushed stones 22 into the crushed stone input port 21 can adjust the direction of the front side left and right around the base end, and the height of the front side can be adjusted up and down, so that it is easy to align it with the crushed stone input port 21. Furthermore, the attachment part 121 is provided so as to be movable back and forth with respect to the bottom part 115 and to be fixed in position at a moving position, and the attachment part 124 is provided so as to be movable back and forth with respect to the side part 116 and to be fixed in position at a moving position, and the front and rear positions of the hair body bottom part 120 and the hair body side part 123 are configured to be adjustable, so that it is easy to align it with the crushed stone input port 21, and even if the diameter of the casing pipe used changes, the front and rear positions can be adjusted to accommodate it.

[0154] In addition, the width K of the left and right ends of the hair body side parts 123, 123 is narrower than the left and right width W of the crushed stone inlet 21, and the width K is 0.6 times to 0.9 times the left and right width W, and the tips of the left and right hair body side parts 123, 123 are arranged so that they can be inserted into the crushed stone inlet 21, so that the crushed stone 22 can be reliably input into the crushed stone inlet 21. In addition, the left and right hair body side parts 123, 123 are broom-shaped, and the base ends of the multiple hairs 122 are bound together, and the tip sides of the hairs 122 are bundled so that they spread out, so that there is a gap between the hairs 122 at the tip side, and part of the soil other than the crushed stone 22 falls from the tip end 113S of the input path at the tip side, and the intrusion of soil into the casing pipes 10, 10A can be suppressed.

[0155] In addition, since the automated material transport device 131 is equipped with a clamshell bucket 147 as a crushed stone lifting means, a large amount of crushed stone 22 can be efficiently transferred to the storage section 110.

[0156] Furthermore, crushed stone piles 153 for sewer pipes are arranged in a staggered pattern so as to sandwich the sewer pipe 152, and four crushed stone piles 153A for manholes are provided to surround the periphery of the manhole 151, resulting in an arrangement of crushed stone piles that is highly effective in preventing liquefaction.

[0157] In addition, a tip bit 81 serving as a drilling bit is provided at the tip of the rod 9, and a lower helical wing 82 serving as a tip side helical wing and an upper helical wing 84 serving as a base side helical wing in the same spiral direction are provided at the tip side of the rod 9, and a gap 83 is provided in the longitudinal direction of the rod 9 between the lower helical wing 82 and the upper helical wing 84.Therefore, by filling the gap 83 with crushed stone 22 serving as a filling material and inserting the casing pipe 10 into the ground, the crushed stone 22 acts as a lid to prevent the excavated soil from entering the casing pipe 10.

[0158] Furthermore, if the crushed stone 22, which is the filling material put into the casing pipe 10, hardens, the connecting lid 85 can be switched to a non-rotating mode and the rod 9 can be rotated while the casing pipe 10 is not rotating, thereby stirring and loosening the hardened crushed stone 22.

[0159] In a liquefaction prevention method using a ground improvement method in which a rod 9 having helical wings 82, 84 and a casing pipe 10 fitted around the rod 9 are inserted into the ground to a predetermined depth, and the rod 9 is rotated in the direction opposite to excavation to form crushed stone piles 153, 153A as compaction piles in the ground with crushed stone 22 as a filling material in the casing pipe 10, a lower helical wing 82 as a tip side helical wing and an upper helical wing 84 as a base side helical wing are provided at the tip side of the rod 9 in the same helical direction, and a longitudinal direction of the rod 9 is formed between the lower helical wing 82 and the upper helical wing 84. A gap 83 is provided, and with the lower spiral blade 82 protruding from the tip of the casing pipe 10, the rod 9 is inserted to the specified depth while rotating together with the casing pipe 10 in the anti-excavation direction. By filling the gap 83 with crushed stone 22 as a filler material to prevent the excavated soil from entering the casing pipe 10, the rod 9 is inserted together with the casing pipe 10 while rotating in the anti-excavation direction, so that the casing pipe 10 can be inserted to the specified depth while compacting the ground, and a columnar cylindrical space for introducing crushed stone can be secured inside the casing pipe 10.

[0160] In addition, in soft ground, the lower spiral blade 82, which is the tip side spiral blade, inserts the rod 9 together with the casing pipe 10 while rotating in the counter-excavation direction, and in ground where the lower spiral blade 82 is harder than soft ground and cannot be inserted by rotating in the counter-excavation direction, the rod 9 is inserted while rotating in the excavation direction.Therefore, in ground where it is not possible to insert the rod 9 and casing pipe 10 by rotating in the counter-excavation direction, the rod 9 can be switched to rotating in the excavation direction, and the underground soil is loosened and stirred while excavating, and then the rotation is returned to the counter-excavation direction so that the rod 9 and casing pipe 10 can be inserted into the ground.

[0161] Furthermore, the discharge of the soil and crushed stone 22 from the lower end of the casing pipe 10 and the compaction of the crushed stone 22 discharged from the lower end using the rod 9 are not performed in the lateral earth pressure influence range H, or the load applied to the crushed stone 22 is lower than in other parts, so that a large lateral load is not applied to the hollow underground structure. Also, the hardness of the ground at the position of the spiral blades 82, 84 is judged based on the reaction force of the ground applied to the spiral blades 82, 84 and the rotation torque value of the spiral blades 82, 84, and if the lateral earth pressure influence range H is hard ground, the force applied to the ground by the spiral blades 82, 84 is lowered or no force is applied compared to soft ground, and the number of rotations of the spiral blades 82, 84 is reduced or the spiral blades 82, 84 are not rotated, so that the lateral earth pressure in the lateral earth pressure influence range H can be reduced.

[0162] Furthermore, as an effect of this embodiment, since the upper helical blade 84 has fewer turns in its spiral than the lower helical blade 82, the lower helical blade 82, which has a greater number of turns, compacts the ground and crushed stone 22 by rotating in the direction opposite to excavation, and since the upper helical blade 84 has a smaller number of turns in its spiral, the crushed stone 22 supplied from above is less likely to become clogged on the upper helical blade 84.

[0163] In addition, crushed stone 22 with a large internal friction angle of 30 degrees or more is used as the filling material, so that the propagation of the compression pressure due to the internal friction angle can be utilized to compact a wider area of ​​the original ground. EXAMPLES

[0164] Fig. 26 shows a second embodiment of the present invention, in which the same parts as those in the first embodiment are given the same reference numerals and their explanations are omitted. As shown in the figure, this embodiment shows an example of construction in a weak layer.

[0165] In this embodiment, an extension casing pipe 10B having a length of 2.5 m is used, which is longer than that in embodiment 1. Also, the anti-vibration frame 13 is of a type that is placed on or adjacent to the ground G.

[0166] By installing the anti-sway frame 13 on the ground G, the extension casing pipe 10A can be connected with the first casing pipe 10 inserted deeper than in Example 1, and a long extension casing pipe 10A can be used, and crushed stones 22 can be fed into the casing pipes 10, 10A from the crushed stone inlet 21 located above the anti-sway frame 13. Also, in Example 1, if the anti-sway frame 13 is installed on the ground G and the casing pipe 10 is inserted into the ground up to a height of, for example, 200 mm from the upper end of the anti-sway frame 13, the first casing pipe 10 can be inserted deeper into the ground, and a long extension casing pipe 10A can be used.

[0167] In this way, the present embodiment provides the same functions and effects as the first embodiment.

[0168] The present invention is not limited to the present embodiment, and various modifications are possible within the scope of the present invention. For example, in the embodiment, the tip bit is shown to be in the shape of a triangular pyramid, but the number of corners may be four or more, such as a square pyramid or a pentagonal pyramid. In addition, the hollow underground buried object may be applied to various objects such as water pipes and tunnels that are hollow and buried underground, other than the manholes, sewer pipes, and septic tanks shown in the embodiment. Furthermore, in the embodiment, a connecting structure using a pair (two) of connecting tools and a pair (two) of connecting receivers is shown, but three or more may be used for connection. Furthermore, although not corresponding to the claims, it goes without saying that the present invention can be used in ground improvement methods other than liquefaction prevention methods. Furthermore, the locking means 18 for locking and unlocking the tips of the right separate frame parts 16L and 16R may be a vertical pin that is inserted and removed between the tips. Furthermore, the number of turns of the lower spiral blade 82 and the upper spiral blade 84 is not limited to that in the embodiment, and the number of turns can be appropriately selected, such as more or less than that in the embodiment. [Explanation of symbols]

[0169] 1 Ground improvement equipment 2. Body 5. Leader 7 Rotational drive unit 8 Lifting drive unit 9. Rod 9A Extension rod 9S End Rod 9K Base Rod 10 Casing Pipe 10A, 10B Extension casing pipe 21 Crushed stone inlet 22 Crushed stone (filling material) 31 Anti-rotation means 40 Reinforcement member 41 Opening and closing means 42 Lid (opening and closing lid) 51 Slide hole 52 Lid hole 53 Lock bolt (operating body) 82 Lower spiral blade (tip spiral blade) 84 Upper spiral wing (tip side spiral wing) 112 Input route 112S Input path tip (tip) 131 Material handling equipment 132 Vehicles (self-propelled vehicles) 135 Cargo Bed 141 Hoist (loading and unloading equipment) 147 Clamshell bucket (means for lifting crushed stone) 151 Manholes (sewer pipes, hollow underground structures) 152 Sewer pipes (sewer pipes / hollow underground structures) 153 Crushed stone piles for sewer pipes 153A Crushed stone piles for manholes 161 Borehole

Claims

1. A rod that is rotated by a rotary drive device and inserted into the ground; A casing pipe is attached to the rod, has a crushed stone inlet on the outer periphery, and is inserted into the ground. A method for preventing liquefaction of sewer pipelines and underground buried objects, characterized in that a borehole is formed below the sewer pipeline or underground buried object using the rod and the casing pipe, and crushed stone is poured into the borehole to construct a crushed stone pile.

2. 2. The method for preventing liquefaction of sewerage pipelines and underground buried objects according to claim 1, characterized in that the method is carried out while the existing sewerage pipelines or underground buried objects are still in use.

3. 2. The liquefaction prevention method for sewer pipelines and underground buried objects according to claim 1, characterized in that after the casing pipe and the lower part of the rod are inserted into the ground, the connection between the rod and the rotary drive device is released, the rotary drive device is moved upward, and below the rotary drive device, the lower end of an extension casing pipe and the lower end of an extension rod are connected to the upper end of the casing pipe and the upper end of the rod.

4. 2. The device for use in the liquefaction prevention method described in claim 1, characterized in that a self-propelled vehicle is provided with a loading platform for loading crushed stone and a loading / unloading device for loading and unloading the crushed stone onto the loading platform.

5. 2. An apparatus for use in the liquefaction prevention method described in claim 1, characterized in that the apparatus is provided with an input path for inputting crushed stone into the crushed stone inlet, and the input path is provided with a flexible tip portion.

6. 2. The apparatus for use in the liquefaction prevention method according to claim 1, further comprising an opening / closing means for opening and closing the plurality of crushed stone inlets.

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