JP4000340B2 - Excavation stirring bit for underground pile construction and ground improvement method using it - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
TECHNICAL FIELD The present invention relates to an excavation stirring bit for underground pile creation that makes it easy to improve soft ground by reducing underground soil and making an underground pile, and a ground improvement method using the same.
[0002]
[Prior art]
Conventionally, many ground improvement methods have already been implemented for soft ground improvement. However, most of them, when creating underground piles, are accompanied by the discharge of excavated earth and sand (mud), and it is necessary to carry out the discharge mud soil and muddy water treatment. A lot of expense is required for processing.
[0003]
As one means for solving such a problem, there is a construction method in which cement milk is pumped into excavated soil inside a hole to be excavated and an underground pile is formed by mechanical stirring. Among them, as a construction method that is said to have a small amount of mud, it is excavated by rotating a loop type bit with a spiral blade around the tip of the pipe, and corresponding to the depth of the hole to be drilled. Using a connecting pipe composed of double pipes, when N value is high, air and water are mixed and pumped while excavating the hole while excavating the hole of predetermined depth, and then rotating with air and cement A method of pumping the injection material mixed with milk and injecting it into the excavated soil in the drilled hole from the injection pipe and mixing it to create a high-density pile in the ground, and the machine stirring air cement milk used for it A mixed pumping device has been proposed (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
JP-A-2002-97629
[Problems to be solved by the invention]
However, in the above-described excavating machine agitation method, the method using the spiral blades is used to cut the surroundings with the spiral blades after excavation by the leading cutter bit. However, when the N-value increases, the workability of excavation is significantly reduced. Further, mixing of excavated soil and cement milk after excavation of the hole is not performed sufficiently, and it is difficult to create a high-density underground pile.
[0006]
The problem with using the spiral blades (spiral blades) is the continuous spiral blade, so when the N value is small, the ground can be dug down by screwing, but the N value is large. Indeed, the contact frictional resistance with the ground (excavated soil) increases, resulting in a great resistance to digging. In addition, with continuous spiral blades, when soil is excavated on soft ground, clayey earth and sand adhere to the blade surface, which is a factor that further increases resistance. Therefore, the crispness between the blade and the excavated earth and sand is poor, and the fact that the mixed state with the injected cement milk after excavation is not sufficiently performed is a factor that does not lead to the creation of high-density underground piles It is inferred.
[0007]
Further, since the excavating mechanism has a spiral blade structure, the structure becomes complicated and the manufacturing cost increases and the cost becomes high. Further, there is a problem that a large amount of power is required for the rotational drive, and in particular, when excavation work cannot be performed smoothly when the underground pile is formed on the ground having a large N value.
[0008]
The present invention has been made to solve the above-described problems, and facilitates excavation regardless of the N value when excavating soft ground, and cement milk injected with excavated soil after excavation. To improve the work performance by improving the mixing function with the ground, and to provide an excavation stirring bit for underground pile creation that enables the creation of high-density underground piles and a ground improvement method using the same It is the purpose.
[0009]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the excavation stirring bit for underground pile formation according to the first invention is:
A tubular rod that is provided with an air pipe and a high-pressure water pipe inside and can be sequentially connected, and a rotational force is applied to the upper part ;
A bulging-shaped bit body provided on the outer side of the tip conduit disposed at the distal end of the tubular rod, the upper and lower portions being welded by a tapered portion,
Twist blade type bit arranged in a plurality of stages on the outer periphery of the bit body, each having two blade members arranged radially and having a downward twist inclination angle with respect to the excavation side;
A tip bit provided at the tip of the leading conduit,
The envelope drawn by the outer ends of the multi-stage twisted blade type bit is formed in a tapered shape with a tapered shape toward the tip, and the lower one is provided with a phase shifted from the uppermost one. ,
The blade member of the uppermost twisted blade type bit is provided with an air pipe and a high-pressure water pipe branched from the air pipe and the high-pressure water pipe in the leading pipe, respectively, and at the tips of the air pipe and the high-pressure water pipe. An air injection nozzle and a fluid injection nozzle are provided,
An air injection nozzle is provided at a tip of an air pipe in the tip conduit at a lower end portion of the tip conduit .
[0010]
In the present invention, when the underground pile is formed on the soft ground, the tip conduit of the tubular rod is rotated with respect to the ground by known driving means (a device for driving the tubular rod by a hydraulic motor supported by the leader). , a hole in the result in the ground twisting vane bit provided with a plurality of stages are drilled sequentially periphery diameter increases from the tip. At this time, pressurized air or pressurized air and pressurized water to the shield while spraying injected into ground from the tip portion and the previous end of it than the upper vane bit tubular rod according to the state of the ground. By doing so, twisting vane bit rotation disposed in a plurality of stages, since given a twist angle cut into the ground, partly or in a state of high N value of the ground is a low state However, since the bit portion is provided intermittently in the rotation direction, the bit is cut into the ground and the rotating portion is dug up, but the excavated earth and sand are dug up without being lifted up. In short, the ground around the actual excavation range by the twisted blade type bit by the air and high pressure water that works by simultaneously digging the earth and sand to the required depth excavated by the rotation of the twisted blade type bit and injecting in the radial direction. Can be loosened to increase the apparent diameter of the drilling hole. After excavating to the required depth, when the tubular rod is reversed while injecting high-pressure air and cement milk from the injection nozzle , the twisted blade type bit is gradually lifted by the reverse rotation, and at the same time, the cement milk injected into the excavated earth and sand Underground piles can be created without mixing mud and producing mud soil.
[0011]
According to the present invention, at the time of the construction operation of the so-called mechanical stirring type underground pile, the twisted blade type bit is arranged in a plurality of stages in the circumferential direction in the tip conduit of the tubular rod. By reducing the resistance at the time of cutting in, the driving force can be reduced and the cutting operation can be easily performed. Also, during the stirring and mixing operation of the excavated soil and the injected cement milk at the time of reverse rotation, the intermittently provided twisted blade type bit can act as a stirring blade and can effectively perform the mixing operation. The excellent effect that the underground pile can be reliably constructed is obtained.
[0012]
Further, according to the present invention, since the twisted blade type bit is disposed on the outer periphery of the bulging-shaped bit body, the base end portion of the twisted blade type bit can be firmly attached to the bit body and excavated. Power can be secured. Moreover, there exists an advantage that the piping branch structure part of injection fluid can be ensured.
[0013]
Moreover, twisting vane bits disposed in a plurality of stages is, since those less stages to that of the uppermost stage is provided by shifting the phase, it facilitates the cutting into the ground, cement There is an advantage that the stirring effect can be enhanced by raising and lowering by means of the upper and lower twisted blade type bits during the mixing operation of milk and excavated soil. Further, since excavation soil is not sandwiched between the upper and lower twisted blade type bits during both excavation and mixing operations, an effect of efficiently performing work can be obtained. Further, the twist vane bits than are provided to have a twist angle of inclination of the downwardly relative to the excavation side, actively excavation in the ground by being given a rotational force in the forward direction, When a rotational force in the reverse direction is applied, an ascending force is applied, and at the same time, the mixing function can be effectively exhibited.
[0014]
The first shot Oite bright, the air pipe and the high-pressure water pipe from the tubular rod to the air injection nozzle and the fluid injection nozzle to the air injection nozzle of the lower end portion and the twist vane bit tip of the destination conduit is independently preferably, that are to be guided by the passage (second invention). By carrying out like this, the supply path of a liquid (high pressure water or cement milk) and high pressure air can be ensured, and the operation | movement injected into the ground or excavated soil can be ensured. Moreover, the twisting air piping and high pressure water pipe provided in vane bits, provided by the double-pipe structure through the center of the blade member, the air injection nozzle and the fluid injection nozzle of the distal end of the blade member Is preferably surrounded by a double injection nozzle ( third invention). By configuring in this way, the function of the twisted blade type bit is not impaired, the strength is increased, and the spray nozzle is protected so as not to be disturbed by earth pressure during excavation and can withstand long-term use. Combined effects.
[0015]
Next, the ground improvement method according to the fourth invention is:
The tubular rod in the excavation and agitation bit formed in the underground pile according to any one of the first to third inventions is sequentially connected to a drill head attached to a work machine support structure attached to a crawler traveling vehicle. Let the insertion support,
a) At the time of drilling work, the ground is excavated and propelled by a tip bit that rotates the tubular rod forward and is attached to the leading portion and a twisted blade type bit arranged in multiple stages,
b) In a state where the N value of the ground is low, excavation is performed while injecting pressurized air into the ground from the air injection nozzle at the lower end of the leading conduit and the air injection nozzle at the tip of the twisted blade type bit,
In N values of c) soil is high, is injected from the air injection nozzle tip of the air injection nozzle and twisting vane bit at the lower end of the lead pipe pressurized air into the ground, yet their twisting vane bit Drilling while jetting high pressure water from the fluid jet nozzle at the tip ,
d) After excavation to the required depth, pressurize air from the air jet nozzle at the lower end of the leading conduit and the tip of the twisted blade type bit while reversing the tubular rod, and from the fluid jet nozzle at the tip of the twisted blade type bit. Cement milk is spouted and pulled up gradually.
e) a mixture of excavated soil and its cement milk by jetting injection of the jet as well as cement milk rotation of twist vane bit and pressurized air is characterized in that construct a underground pile.
[0016]
According to this invention ( 4th invention), the effect described in the said 1st invention-the 3rd invention can be exhibited, and the creation of a high-density underground pile can be performed efficiently according to geology.
[0017]
In the fourth invention, when the underground pile after drilling is created, each time a predetermined amount of cement milk is pumped and the excavation stirring bit is appropriately lifted, the rotation operation is performed without increasing the required time, It is preferable that the cement milk and the excavated soil are stirred and mixed at this position, and this is repeated (the fifth invention). By doing so, it is possible to create a high-density underground pile with enhanced mixing and consolidation effect.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of an excavation stirring bit for underground pile formation according to the present invention and a ground improvement method implemented using the excavation stirring bit will be described with reference to the drawings.
[0019]
FIG. 1 is a side view in which a working machine equipped with an excavation stirring bit according to the present embodiment is attached to the front part of a track-type construction machine, and a view in which a mode during excavation is also shown. 2 is a plan view of FIG. 1, FIG. 3 is a front view (a) and a side view (b) showing a section of the excavation stirring bit of this embodiment, and FIG. FIG. 5 is a partial cross-sectional enlarged detail view of the main bit, and FIG. 6 is a plan view showing a part of the main bit in a plane cross section. b) and a BB end view (c) of FIG. 5 are shown respectively.
[0020]
The excavation agitation bit 10 of this embodiment is attached to the distal end portion (front conduit 11 ′) of the tubular rod 11 that can be sequentially connected, and a twisted blade type bit (described later) for performing excavation agitation operation in a plurality of stages. The tip bit 12 is provided at the leading edge (lower end). In addition, an air pipe 15a and a water / cement milk pipe 16a are sequentially connected to the inside of the tubular rod 11, so that the side of the attachment portion of the tip bit 12 and the outer end portion of the uppermost twisted blade type bit are arranged. Are provided with spray nozzles 20 and 17 connected to the air pipe and the water / cement milk pipe. In addition, a spray nozzle is provided downward at the tip of the leading conduit 11 '.
[0021]
The twisted blade type bits 14 (hereinafter referred to as blade type bits 14) arranged in a plurality of stages are formed of a thick bit main body 13 which is coaxially connected to the leading conduit 11 'and welded to the outside with a tapered portion on the outside. Two blade members that are perpendicular to the shaft core and are opposed to each other in the radial direction so as to have a downward slope in the excavation rotation direction are attached to the outer periphery by welding their base ends. The uppermost blade-type bit 14A becomes the main bit, and the next blade-type bit 14B is provided at a position displaced by 90 °. Further, the lowermost blade-type bit 14C has a large inclination angle and has the middle stage. The blade-type bit 14B is attached with a displacement of approximately 90 °. In short, the blade-type bits 14A, 14B, 14C of each stage in the vertical direction, in particular, the main bit 14A and the lower bit (middle-stage blade-type bit 14B) are not overlapped. It should be noted that the middle blade type bit 14B and the lowermost bit 14C are in a state of not interfering with either excavation or agitation because the lowermost blade type bit 14C has a large inclination angle.
[0022]
Further, in the blade-type bits 14A, 14B, and 14C of each stage, the vertical envelope D (see FIG. 3B) formed by the locus of the circle drawn by the outer ends thereof has a tapered shape of a lower depression. Thus, the length dimension of the blade member at each stage is set.
[0023]
Further, the blade member 14a of the main bit 14A has an air pipe 15 and cement milk (from the inside of the leading pipe 11 'through the inside of the bit body 13 as shown in FIGS. 5 and 6A to 6C). A high-pressure water) pipe 16 is arranged in the center, and a double-structure injection nozzle 17 (an injection nozzle 17b for injecting fluid from the pipe 16 in the center) is separately connected to both pipes 15 and 16 at the tip. The air injection nozzle 17a which is coaxial and has an annular shape is integrally mounted on the outside thereof. The pipes 15 and 16 are provided with a double pipe at the center of the blade member 14a, and are substantially arranged along the outside of the double pipe with separate blade members 14a and 14a arranged on both sides. The blade members 14a are welded by separate connecting members 14d that cover the upper and lower sides of the double pipe, and the base ends of the blade members 14a are welded to the bit body 13 to be integrated. The periphery of the injection nozzle 17 is surrounded by a cylindrical protective member 18 so that the injection nozzle 17 is not damaged during excavation.
[0024]
The air pipe 15 a, the cement milk (high pressure water) pipe 16 a and the double pipe (the air pipe 15 and the cement milk (high pressure water) pipe 16) in the tip pipe 11 ′ A distribution piece 19 integrated with a connecting member 19 ′ protruding from the conduit 11 ′ is provided, and the pipes 15 a and 16 a are connected to branch holes 19 a and 19 b of the distribution piece 19. Note that the air pipe 15a and the cement milk (high pressure water) pipe 16a can be easily connected to the tubular rod 11 sequentially connected by a well-known joint, and the top end of the tubular rod located at the uppermost part. The swivel joint 25 is attached, and is connected to a high-pressure air source (not shown) (for example, a compressor), a high-pressure pump and its control device, a cement milk supply pump, a chemical supply pump, etc. . In FIGS. 3 and 5, reference numeral 22 in the drawing is a tubular rod joint, and 23 is a coupling type pipe joint.
[0025]
In the middle blade type bit 14B, the base ends of the blade members 14b and 14b having required dimensions are welded to the side surface of the bit body 13 at a required inclination angle. The blade members forming the blade-type bits 14 (generally indicated) are made of hard steel and are heat-treated as necessary to increase the hardness of the cutting edge portion (outer periphery and front side in the excavation direction). Those having higher wear resistance are used. If necessary, a hard material may be additionally deposited on the cutting edge portion, or a hard tip may be attached by welding.
[0026]
In order to improve the ground using the excavation stirring bit 10 of this embodiment configured as described above, a specific embodiment will be described. First, as shown in FIG. Excavator 30 (seventh) supported by a boom 4 with a base end attached to the upper swing body 3 in a undulating manner on the front side of a tracked construction machine vehicle 1 including the upper swing body 3 supported via It corresponds to the working machine support structure part of the invention) and is used.
[0027]
The excavator 30 is a leader that pivotally supports a base bracket 31 by a support shaft pin 5 at the front end of a boom 4 of a tracked construction machine vehicle 1 and supports the bottom on the boom 4 side so that it can be raised and lowered. 32, a drill head 35 disposed through a slide frame 34 slidable in the vertical direction by a slide cylinder 33 on the front surface of the reader 32, a tilt cylinder 36 and a reader 32 for adjusting the tilt of the reader 32 in the lateral direction. Outriggers 37 attached to both side surfaces of the lower part of the upper part of the upper revolving body 3 are driven, and the drill head 35 is rotated by receiving power from an engine-driven hydraulic supply means (not shown) mounted on the upper swing body 3. It has become. Similarly, the slide cylinder 33, tilt cylinder 36, and outrigger 37 can be operated by controlling the pressure oil from the hydraulic pressure supply means. In the figure, reference numeral 6 is a boom cylinder for raising and lowering the boom, 7 is an operation cylinder for setting the standing angle of the reader 32, and 38 is a fixing means for fixing the tubular rod.
[0028]
The excavation agitation bit 10 of the present embodiment is attached to the tip of the tubular rod 11 attached to the excavator 30 supported on the front side of the tracked construction machine vehicle 1, and the construction machine reaches the target work position. The vehicle 1 is moved and moved to the drilling position, and the air pipe and the water / cement milk pipe are connected to the separately installed fluid supply units to make preparations. Thereafter, the tilt cylinder 36 and the operation cylinder 7 on the vehicle side are operated to set the alignment and level of the excavation stirring bit 10 via the reader 32. After that, the ground improvement work will be performed according to the following procedure. This embodiment will be described with reference to a schematic diagram shown in FIG.
[0029]
(Example)
I) Drilling and creation of underground piles (when N value is 10 or less)
[0030]
a) Drilling process The drill head 35 is driven to rotate the excavation agitation bit 10 forward (for example, the maximum diameter of the excavation agitation bit is 1000 mm and the rotation speed is 40 rpm). Push into the. At this time, excavation is performed while jetting pressurized air from the jet nozzle 20 at the lower part of the front conduit 11 ', the jet nozzle 21 at the lower end, and the jet nozzle 17 at the tip (outer end) of the main bit (uppermost blade type bit) 17A. (See FIG. 7A).
[0031]
If it does in this way, the effect which stirs the earth and sand excavated with the pressurized air which is excavated with the excavation stirring bit 10 and injected will be acquired. That is, the excavation stirring bit 10 is excavated by the twisted blade type bits 14A, 14B, and 14C arranged in multiple stages as described above, and each of the blade type bits 14 has a blade member to which the twisted blade member 13 is added. Since each blade type bit 14 cuts into the ground, the excavated earth and sand are not pushed up and discharged, but only lifted within a range corresponding to the torsion angle of the blade. Therefore, if this excavation agitating bit 10 is not propelled, it works to agitate the excavated soil E at the rotating portion, and in addition to this, a stirring force is added by the injection of pressurized air, and the surrounding area exceeds the excavated diameter. The ground E ′ will also be in an excavated state.
[0032]
When the slide cylinder 33 is propelled for the maximum stroke in such a state, the tubular rod 11 is fixed by the fixing means 38 (fixed chuck) provided at the top of the leader, and is incorporated in the drill head 35 (not shown). The rotary chuck is opened and the drill head 35 is pulled up to the uppermost position by contracting the slide cylinder 33. Thereafter, the rotary chuck is tightened, and the fixing by the fixing means 38 at the upper part is released, and the operation proceeds to the drilling operation. Excavation drilling is performed by repeating such operations. When the drilling progresses, for example, when the drilling depth exceeds about 8 m, the tubular rod 11 is added to perform the above operation. In this drilling step, as described above, a drilling hole having a required diameter is formed, but the excavation soil is not performed at that time, and the excavation soil E remains in the drilling hole portion. The excavation diameter and the range of the surrounding ground E ′ are substantially excavation holes (see FIG. 7B).
[0033]
b) When excavating to the required depth of the underground pile creation process, the excavation stirring bit 10 is rotated in reverse. At the same time, low pressure air is ejected from the jet nozzle 21 at the lower end of the front conduit 11 ′, high pressure air is jetted from the tip jet nozzle 17 a of the main bit 14 A, and tip jet nozzle 17 b of the main bit 14 A from the lower jet nozzle 20. Then, the cement milk is sent from the above-defined predetermined amount above the ground (for example, supply pressure 15 to 20 Mpa) and injected (see FIG. 7C).
[0034]
When the high-pressure air and cement milk are jetted and injected toward the excavation soil E in the excavation hole and the ground E ′ around the excavation hole wall while rotating the excavation agitation bit 10 in this way, the blade-type bit 14 is rotated. Contrary to the drilling process, the excavated soil is repeatedly stirred and the high-pressure air that is ejected actively expels the cement milk that is ejected at the same time in the ground around the drilling hole. Introducing the agitated state by rotating the blade-type bit and the high-pressure air jet oblique, the surrounding ground is also combined, and the excavated soil and cement milk are in a range of diameters larger than the original excavated hole diameter. Mixing is done.
[0035]
In such an operation, the pulling speed of the tubular rod 11 by the slide cylinder 33 is intermittently stopped. For example, when the pulling up of 25 mm is performed, the rising operation is stopped for a certain time and the stirring operation is repeated at the same place. Of course, during this time, a prescribed amount of cement milk is supplied and mixed with the excavated soil. By performing the operation of rotating the blade type bit at the same place for a certain period of time, the stirring / mixing and consolidation functions are performed simultaneously, and the pressure density at the mixing part is increased, and the underground pile creation operation is performed. .
[0036]
In this way, the operation of sequentially raising and mixing the excavation agitation bit 10 by the required dimension P is repeated, and when reaching the ground part, as shown in FIG. Middle pile F will be created.
[0037]
When building the underground pile described above, for example, when creating an underground pile having a diameter of about 1600 mm larger than the diameter of 1000 mm of the excavation stirring bit 10, the increased diameter pile is formed by jet stirring with the supply pressure of cement milk being 20 to 30 Mpa. Can be created.
[0038]
II) drilling and Construction of underground pile (not less than N value 10)
[0039]
c) Drilling Step As in the case described above, the excavation stirring bit 10 is rotated in the forward direction and is gradually pushed into the ground by the slide cylinder 33. At this time, low-pressure air is jetted from the jet nozzle 21 at the lower end of the front conduit 11 ′, high-pressure air is jetted from the jet nozzle 17a at the tip of the main bit 14A, and further, N value from the jet nozzle 17b at the tip of the main bit 14A. And high pressure water of 20-30 Mpa is sprayed according to soil quality. At this time, high-pressure water to which a small amount of a chemical solution (for example, a surfactant aqueous solution) having a function of dissolving clay is added is used. By doing so, it is possible to prevent the clay type soil from adhering to the blade-type bit 14 during excavation of the ground by the blade-type bit 14 and to increase the resistance, and at the same time, increase the stirring diameter increasing effect. In this excavation operation, excavation is performed up to the required depth in the same procedure as in the previous embodiment.
[0040]
d) Formation process of underground pile This operation is the same as b) of Example I.
[0041]
In this way, regardless of the N value, the underground pile is created by changing the excavation position by the excavation agitation bit 10 to the underground pile formation position sequentially at the required interval with respect to the target ground as described above. To do. The excavation and agitation operation and the creation of underground piles are carried out based on data obtained by conducting a survey of the soil in advance for the injection of the pressure fluid described above.
[0042]
As described above, according to the present invention, by using the excavation stirring bit provided with the twisted blade type bit in multiple stages, the excavated earth and sand and cement milk can be effectively stirred and mixed. Can be implemented efficiently. In addition, the soil can cope with soil with N ≧ 10 in both sandy soil and viscous soil (C = 0.5 or more). In addition,
In the case of N <10, there is almost no mud (drainage) by excavation and creation.
In the case of N> 10, a little mud (sewage) is generated by excavation and creation, but the amount of mud is very small as compared with the high-pressure jet stirring method that has been conventionally carried out.
Therefore, it can be said that a very small amount of industrial waste generated as an improvement method for this kind of soft ground has a great effect on environmental improvement.
[0043]
The above-described excavation agitation bit has been described based on an embodiment in which two blade members are opposed to each other and arranged in multiple stages, but is not limited to this, and two or more, for example, three as necessary. You may make it arrange | position equally. Further, the number of arrangement stages may be three or more.
[Brief description of the drawings]
FIG. 1 is a side view in which a working machine equipped with an excavation stirring bit according to the present embodiment is attached to the front of a track-type construction machine, and is a view in which an aspect during excavation is also shown.
FIG. 2 is a plan view of FIG. 1;
FIG. 3 is a front view (a) and a side view (b) showing a cross section of a part of the excavation stirring bit of the present embodiment.
4 is a plan view of FIG. 3 (a). FIG.
FIG. 5 is an enlarged detail view of a partial cross section of a main bit.
6 is a diagram (a) showing a part of the main bit in a plane cross section, an AA view (b) in FIG. 5 and an end view (C) in BB in FIG. 5;
FIGS. 7A to 7D are schematic views for explaining the point of construction work for underground piles according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tracked construction machine vehicle 3 Upper turning body 4 Boom 10 Excavation stirring bit 11 Tubular rod 11 'End pipe 12 End bit 13 Bit body 14 Twist blade type bit 14A Main bit (uppermost blade type bit)
14B Middle stage blade type bit 14C Bottom stage blade type bit 15, 15a Air pipe 16, 16a Water / cement milk pipe 17, 20 Spray nozzle 18 Protective member 19 Distributing piece 21 Bottom spray nozzle 30 Excavator 32 Leader 33 Slide Cylinder 34 Slide frame 35 Drill head 38 Fixing means for tubular rod

Claims (5)

A tubular rod that is provided with an air pipe and a high-pressure water pipe inside and can be sequentially connected, and a rotational force is applied to the upper part ;
A bulging-shaped bit body provided on the outer side of the tip conduit disposed at the distal end of the tubular rod, the upper and lower portions being welded by a tapered portion,
Twist blade type bit arranged in a plurality of stages on the outer periphery of the bit body, each having two blade members arranged radially and having a downward twist inclination angle with respect to the excavation side;
A tip bit provided at the tip of the leading conduit,
The envelope drawn by the outer ends of the multi-stage twisted blade type bit is formed in a tapered shape with a tapered shape toward the tip, and the lower one is provided with a phase shifted from the uppermost one. ,
The blade member of the uppermost twisted blade type bit is provided with an air pipe and a high-pressure water pipe branched from the air pipe and the high-pressure water pipe in the leading pipe, respectively, and at the tips of the air pipe and the high-pressure water pipe. An air injection nozzle and a fluid injection nozzle are provided,
An excavation stirring bit for underground pile formation, wherein an air injection nozzle is provided at a tip of an air pipe in the tip conduit at a lower end portion of the tip conduit . The air pipe and the high-pressure water pipe from the tubular rod to the air injection nozzle and the fluid injection nozzle to the air injection nozzle of the lower end portion and the twist vane bit tip of the destination conduit, that is to be guided by the independent passages drilling stirring bit of ground stakes Construction according to 請 Motomeko 1. The twist vane air pipe and the high-pressure water pipe is provided to the bit is provided with a double-pipe structure through the center of the blade member, the tip air injection nozzle and the fluid injection nozzle of the blade member is vertically The excavation stirring bit for underground pile formation according to claim 1 or 2 , wherein a double injection nozzle is enclosed. The tubular rod in the excavation stirring bit for underground pile formation according to any one of claims 1 to 3 is sequentially connected to a drill head attached to a work machine support structure attached to a crawler traveling vehicle. Let the insertion support,
a) At the time of drilling work, the ground is excavated and propelled by a tip bit that rotates the tubular rod forward and is attached to the leading portion and a twisted blade type bit arranged in multiple stages,
b) In a state where the N value of the ground is low, excavation is performed while injecting pressurized air into the ground from the air injection nozzle at the lower end of the leading conduit and the air injection nozzle at the tip of the twisted blade type bit,
In N values of c) soil is high, is injected from the air injection nozzle tip of the air injection nozzle and twisting vane bit at the lower end of the lead pipe pressurized air into the ground, yet their twisting vane bit Drilling while jetting high pressure water from the fluid jet nozzle at the tip ,
d) After excavation to the required depth, pressurize air from the air jet nozzle at the lower end of the leading conduit and the tip of the twisted blade type bit while reversing the tubular rod, and from the fluid jet nozzle at the tip of the twisted blade type bit. Cement milk is spouted and pulled up gradually.
e) A ground improvement method characterized in that an underground pile is created by mixing excavated soil and its cement milk by rotating a twisted blade type bit, jetting pressurized air, and jetting cement milk. When creating underground piles after drilling, each time the drilling agitation bit is lifted by an appropriate amount by pumping a specified amount of cement milk, the rotation operation is performed without raising the required time, and the cement milk at that position The ground improvement construction method according to claim 4 , wherein agitation and mixing of the soil and the excavated soil are performed, and this is repeated.

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