JP7713487B2 - Self-drilled hole monitoring device and ground improvement method using same - Google Patents

Description

The present invention relates to a self-drilled hole monitoring device used in high-pressure jet mixing methods and the like, and a ground improvement method using the same. More specifically, the present invention relates to a self-drilled hole monitoring device that serves both as a drilling water flow path and a compressed air flow path, and a ground improvement method using the same.

Patent Document 1, previously filed by the present inventor, is a prior art example of a type of self-drilling monitoring device that serves both as a drilling water flow path and a compressed air flow path. In the self-drilling monitoring device described in this document, a porous surface with multiple holes is provided at the drilling water outlet, and when switching from the drilling process to the ground improvement process, multiple steel balls are inserted from the top of the rod to block each hole in the porous surface, thereby blocking the drilling water outlet.

JP 2021-147987 A

However, in the conventional technology described in Patent Document 1, multiple steel balls are injected from the top of the rod (i.e., the ground surface) through a common flow path for the drilling water flow path and the compressed air flow path, thereby blocking the drilling water outlet, so the rod diameter must be relatively large, which is unsuitable for small diameter rods.

The present invention was made in consideration of these problems, and aims to provide a self-drilled hole monitoring device that is not affected by the diameter of the rod and can be applied to small diameter rods, as well as a ground improvement method using the same.

The self-drilling type monitor device of the present invention comprises:
A self-drilling type monitor device comprising: a drilling water outlet, a hardener jet nozzle, a compressed air jet nozzle surrounding the hardener jet nozzle, a first flow path which is a common flow path for drilling water and compressed air, a second flow path for hardener, a third flow path connecting the first flow path and the drilling water outlet, a fourth flow path connecting the first flow path and the compressed air jet nozzle, and a valve for opening and closing the drilling water outlet,
The valve includes a valve body, a valve seat provided below the valve body, spring means for biasing the valve body downward, and restricting means for restricting downward movement of the valve body to prevent it from contacting the valve seat,
The regulating means is characterized in that it is configured such that the restriction is released when water pressure exceeding the water pressure during drilling acts on the valve body.

According to the self-drilling type monitoring device of the present invention, under the water pressure during drilling, the regulating means regulates the valve body from abutting (seating) on the valve seat, and the valve maintains an open state, allowing the drilling process to be carried out without hindrance. On the other hand, by applying water pressure exceeding the water pressure during drilling to the valve body, the regulation by the regulating means is released, the valve body abuts (seats) on the valve seat, and the valve is closed. Therefore, the water pressure acting on the valve body can be increased by increasing the flow rate of drilling water supplied to the first flow path, thereby blocking the drilling water outlet, so there is no need to insert steel balls from the ground surface through the rod as in the conventional technology of Patent Document 1, and it can be applied to rods with small diameters.

In one preferred embodiment of the self-drilled hole monitoring device of the present invention,
At least a part of the regulating means is configured as a fragile part that bends or breaks when water pressure exceeding the water pressure during drilling acts on the valve body,
The restriction by the restricting means may be released by bending or breaking the fragile portion.

In this case, one of the preferred embodiments is as follows:
The regulating means comprises a lateral member extending horizontally across the vertical flow path from the valve body to the drilling water outlet, and a vertical member extending upward from this lateral member toward the valve body, and the lateral member can be configured as the weak part.

Furthermore, in one preferred embodiment of the self-drilling type monitoring device of the present invention, the compressed air injection nozzle may be provided with a sealing member that is released when a pressure exceeding the water pressure during drilling is applied to the nozzle.

By sealing the compressed air injection nozzle with such a sealing member, it is possible to prevent drilling water from leaking out of the compressed air injection nozzle even when drilling water is supplied to the first flow path during drilling. After the drilling process is completed, the seal can be released by applying water pressure to the sealing member that exceeds the water pressure during drilling, and the nozzle can then perform its original function as a compressed air injection nozzle.

Next, the ground improvement method of the present invention is a ground improvement method using the above-mentioned self-drilled hole type monitoring device,
a drilling step of supplying drilling water into the first flow path and rotating the monitor device while discharging the drilling water from the drilling water discharge port to drill a hole to a predetermined depth;
a valve closing step of increasing the water pressure of the drilling water to release the restriction by the restriction means and close the valve;
a ground improvement process in which compressed air and a hardening material are supplied into the first and second flow paths, respectively, while the monitor device is rotated and raised, thereby injecting the compressed air and the hardening material from the compressed air injection nozzle and the hardening material injection nozzle, respectively, to improve the surrounding ground;
The present invention is characterized by comprising:

According to the ground improvement method of the present invention, during the drilling process, the regulating means regulates the valve body from abutting (seating) on the valve seat, and the valve maintains an open state, allowing the drilling process to be carried out without hindrance. On the other hand, by applying water pressure to the valve body that exceeds the water pressure during drilling, the regulation by the regulating means is released, the valve body abuts (seats) on the valve seat, and the valve is closed. Therefore, after the drilling process is completed, the water pressure acting on the valve body can be increased by increasing the flow rate of drilling water supplied to the first flow path, thereby blocking the drilling water outlet, so there is no need to introduce steel balls from the ground surface through a rod as in the conventional technology of Patent Document 1, and the method can also be applied to ground improvement using a small diameter rod.

The ground improvement method of the present invention is a ground improvement method using the above-mentioned self-drilled hole type monitoring device,
a drilling step of supplying drilling water into the first flow path and rotating the monitor device while discharging the drilling water from the drilling water discharge port to drill a hole to a predetermined depth;
a valve closing step of increasing the water pressure of the drilling water to release the restriction by the restriction means and close the valve;
a sealing release step of releasing the sealing of the compressed air jet nozzle by the sealing member using the increased water pressure of the drilling water;
a ground improvement process in which compressed air and a hardening material are supplied into the first and second flow paths, respectively, while the monitor device is rotated and raised, thereby injecting the compressed air and the hardening material from the compressed air injection nozzle and the hardening material injection nozzle, respectively, to improve the surrounding ground;
The present invention is characterized by comprising:

According to the ground improvement method of the present invention, by sealing the compressed air injection nozzle with a sealing member, it is possible to prevent drilling water from leaking from the compressed air injection nozzle even when drilling water is supplied to the first flow path during drilling. After the drilling process is completed, the seal can be released by applying water pressure to the sealing member that exceeds the water pressure during drilling, so that the nozzle can then perform its original function as a compressed air injection nozzle.

In one preferred embodiment of the ground improvement method of the present invention, in the unsealing step, drilling water may be supplied into the first flow path and compressed air may be supplied into the second flow path, and the sealing of the sealing member may be unsealed by the water pressure of the drilling water supplied into the first flow path while the compressed air is sprayed from the hardener spray nozzle.

In this way, by supplying drilling water into the first flow path and compressed air into the second flow path, and spraying compressed air from the hardener spray nozzle while releasing the seal on the compressed air spray nozzle with the water pressure of the drilling water, it is possible to prevent the drilling water from flowing back into the monitor device through the hardener spray nozzle.

According to the present invention, the water pressure acting on the valve body can be increased by, for example, increasing the flow rate of drilling water supplied to the first flow path, thereby closing the valve, so there is no need to insert steel balls from the ground surface through the rod to block the drilling water outlet as in the conventional technology of Patent Document 1, and the invention can be applied to rods with small diameters. Therefore, there is an advantage that it is not affected by the size of the rod diameter.

FIG. 3 is a cross-sectional view of the self-drilled hole monitoring device according to the embodiment (valve in open state). 1A and 1B are enlarged cross-sectional views of the vicinity of the drilling water outlet of the monitoring device, in which (A) shows the valve in an open state and (B) shows the valve in a closed state. 1A is a front view of a rod-shaped member, FIG. 1B is a plan view thereof, FIG. 1C is a front view of a rod receiving member, and FIG. FIG. 1 is a process diagram of a ground improvement method according to an embodiment, in which (A) shows an installation process, (B) shows a hole drilling process, (C) shows a test injection process, (D) shows a ground improvement process (construction process), and (E) shows a rod withdrawal and hole filling process. 1A and 1B are enlarged cross-sectional views of the vicinity of the compressed air injection nozzle of a ground improvement device according to a modified example, in which (A) shows the compressed air injection nozzle sealed by a sealing member 70, and (B) shows the state in which the sealing member 70 is unsealed. 10A is a front view of a sealing member 70 according to a modified example, and FIG. A cross-sectional view of a self-drilled hole monitoring device according to a reference example (valve closed). 1A and 1B are enlarged cross-sectional views of the vicinity of the drilling water outlet of the monitoring device, in which (A) shows the valve in a closed state and (B) shows the valve in an open state. 1A is a front cross-sectional view of the lower ball receiving member, and FIG. 1B is a plan view of the lower ball receiving member.

1. Embodiments of the Present Invention Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The ground improvement device according to the embodiment of the present invention is a ground improvement device equipped with a self-drilled hole type monitoring device 3 that can be used in both the drilling process and the ground improvement process, and as shown in FIG. 4(A), it is equipped with a boring machine M installed on the ground, a rod 1, a swivel 2 attached to the base end (the upper end in the illustrated example) of the rod 1, and a self-drilled hole type monitoring device 3 attached to the tip end (the lower end in the illustrated example) of the rod 1.

As shown diagrammatically in FIG. 1, the rod 1 is a double-tube rod in which a first passage 11, which serves both as a drilling water passage and a compressed air passage, and a second passage 12, which serves as a hardening material passage, are formed. In a cross-sectional view, the second passage 12 is located in the center of the rod 1, and the first passage 11 is arranged concentrically around it.

The swivel 2 is provided with a drilling water and compressed air supply port 2a and a hardening material supply port 2b, and the drilling water and compressed air supply port 2a is connected to the first flow path 11, and the hardening material supply port 2b is connected to the second flow path 12.

The configurations of the boring machine M, rod 1, and swivel 2 in this embodiment are almost the same as those used in conventional double-tube rod-type ground improvement devices, so the following mainly describes in detail the configuration of the self-drilling type monitor device 3.

As shown in Figures 1 and 2, the self-drilling type monitoring device 3 of this embodiment has a metal crown (drilling bit) 31 and a drilling water outlet 32 at its lower end. In addition, in the middle of the monitoring device 3, a hardener injection nozzle 33 and a compressed air injection nozzle 34 surrounding it are concentrically arranged facing to the side.

Inside the monitor device 3, a first flow path 11 and a second flow path 12 are formed, which extend from the inside of the rod 1. Of these, the second flow path 12 extends further inside the monitor device 3 and is connected to the hardener injection nozzle 33.

On the other hand, inside the monitor device 3, the first flow path 11 branches into a third flow path 13 and a fourth flow path 14, with the third flow path 13 connected to the drilling water outlet 32 and the fourth flow path 14 connected to the compressed air injection nozzle 34. In other words, the first flow path 11 is connected to the drilling water outlet 32 via the third flow path 13, and is connected to the compressed air injection nozzle 34 via the fourth flow path 14. Although not shown, multiple third flow paths 13 are formed inside the monitor device 3, and these multiple third flow paths 13 merge downstream and are connected to the drilling water outlet 32.

The monitor device 3 of this embodiment is provided with a valve 4 that opens and closes the drilling water outlet 32. As shown in FIG. 2, this valve 4 is provided with a valve body 4a made of a steel ball, a valve seat 4b provided below this valve body 4a, a compression coil spring 4c that biases the valve body (steel ball) 4a downward, and a restricting member 5 that restricts the downward movement of the valve body 4a.

The restricting member 5 comprises a rod-shaped member 6 arranged vertically within the drilling water outlet passage 32a that communicates with the drilling water outlet 32, and a rod receiving member 7 that is suspended horizontally across the drilling water outlet 32 at the bottom of the outlet passage 32a. The rod-shaped member 6 corresponds to the "vertical member" of the present invention, and the rod receiving member 7 corresponds to the "horizontal member" of the present invention.

As shown in Fig. 3(A)(B), the rod-shaped member 6 is provided with a round rod-shaped rod body 6a and a cross-shaped anti-sway portion 6b in a plan view provided in the vertical center of the rod body 6a. The upper end of the rod body 6a abuts against the valve body 4a and the lower end abuts against the rod receiving member 7, so that the valve body 4a functions as a "tension rod" so that the valve body 4a does not move further downward even if the spring pressure of the compression coil spring 4c or the water pressure of the drilling water during drilling acts on the valve body 4a. On the other hand, the anti-sway portion 6b is for supporting the rod-shaped member 6 straight in the outlet passage 32a so that it does not tilt left and right or fall over, and is formed with an outer shape that fits inside the outlet passage 32a. The anti-sway portion 6b is formed in a cross shape in a plan view in order to allow the passage of drilling water through the gap. In this embodiment, one anti-vibration portion 6b is provided in the center of the rod body 6a, but two or more may be provided along the longitudinal direction of the rod body 6a.

The rod receiving member 7 is configured as a fragile part that bends or breaks when water pressure exceeding the water pressure during drilling acts on the valve body 4a, and is fixed to the drilling water outlet 32 with a screw (not shown) (note that in Figures 3 (C) and (D) the symbol 7a is a screw hole for passing such a screw). As a result, when water pressure exceeding the water pressure during drilling acts on the valve body 4a, the rod receiving member 7 bends or breaks, which releases the restriction of the restricting member 5 and allows the valve body 4a to move downward. Note that "breaking" here includes not only cases where the rod receiving member 7 (horizontal member) itself breaks, but also cases where the screw that fixed it comes loose and the rod receiving member 7 (horizontal member) detaches from the drilling water outlet 32, or even if it does not detach, it is still engaged at only one end.

The compressed air injection nozzle 34 of the self-drilling type monitoring device 3 according to this embodiment is sealed by a sealing member 60. The sealing member 60 in this embodiment is made of an annular aluminum plate, which is fixed around the compressed air injection nozzle 34 by screws (not shown). This sealing member 60 is designed to be able to release the seal when pressure that exceeds the water pressure during drilling is applied to it. Specifically, while the seal is maintained under the water pressure during drilling, the aluminum plate is blown away when pressure that exceeds the water pressure during drilling is applied to it.

The configuration of the sealing member is not limited to the above configuration, and may be that shown in Figures 7 and 8 or Figures 9 and 10 of Patent Document 1. In any case, the hardener injection nozzle 33 is not sealed by the sealing member.

The ground improvement device of this embodiment configured as above is used as follows.
4 is a diagram illustrating the steps of a ground improvement method using the ground improvement device. The steps will be described below in order.

As shown in Fig. 4(A), a boring machine M is installed on the ground, and a rod 1 is attached to the boring machine M. A swivel 2 is attached to the upper end of the rod 1, and the above-mentioned self-drilling type monitor device 3 is attached to the lower end of the swivel 2.

4(B), water or bentonite mud is used as the drilling water W, and this drilling water W is supplied to the drilling water and compressed air supply port 2a of the swivel 2 connected to the first flow path 11, and the drilling water W is discharged from the drilling water outlet 32 at the lower end of the monitor device 3, and the rod 1 is rotated by the boring machine M to drill to a predetermined depth. As described above, the water pressure of the drilling water W during this drilling process does not release the restriction of the restricting member 5, and the sealing member 60 does not release the seal. Therefore, the drilling water W is discharged only from the drilling water outlet 32 at the lower end of the monitor device 3. The mud generated by drilling is sucked and discharged to the ground by the sand pump 50.

During the drilling process, drilling water W may be supplied into the first flow path 11 and compressed air may be supplied into the second flow path 12 to eject drilling water W from the drilling water outlet 32 and eject compressed air from the hardener injection nozzle 33. As described above, since the hardener injection nozzle 33 is not sealed by the sealing member 60, it is possible to eject compressed air from the hardener injection nozzle 33 during the drilling process. In this way, ejecting compressed air from the hardener injection nozzle 33 during the drilling process can promote the discharge of mud generated by drilling to the ground surface.

<3> Valve closing process and seal release process After the completion of the drilling process, when the flow rate (supply flow rate) of the drilling water W to be supplied is increased, the opening degree of the valve 4 is restricted by the regulating member 5, so that the water pressure (internal pressure) in the monitor device 3 rises. This increase in water pressure bends or breaks the rod receiving member 7 configured as a weak part, and the valve body 4a moves downward to close the valve 4. The seal of the sealing member 60 is also released by the increase in water pressure at this time. In addition, when releasing the seal of the sealing member 60, compressed air may be simultaneously supplied into the second flow path 12 and the compressed air may be sprayed from the hardener spray nozzle 33. In this way, by releasing the seal of the sealing member 60 with the drilling water W with increased water pressure while spraying compressed air from the hardener spray nozzle 33, it is possible to prevent the drilling water W from flowing back into the monitor device 3 from the hardener spray nozzle 33.

<4> Test injection process After the valve closing stroke and the sealing release stroke, water W0 for test injection is supplied to the hardener supply port 2b and compressed air A is supplied to the drilling water and compressed air supply port 2a to perform a test injection (Figure 4 (C)).

《5》Ground improvement process (preparation process)
If no abnormality is found, the water W0 for test injection is switched to the hardening material G, and compressed air A is injected from the compressed air injection nozzle 34, while the hardening material G is injected from the hardening material injection nozzle 33. Then, the rod 1 is pulled up while rotating according to a predetermined rotation angle, pulling speed, and rotation speed. As a result, a consolidated body (improved body) 40 is created around the rod 1, and ground improvement is performed (Fig. 4(D)).

<6> Rod Removal and Hole Filling Process After the ground improvement process (construction process) is completed, the rod 1 is removed and the holes are filled. This completes the series of processes (FIG. 4(E)).

As described above, according to the ground improvement device and ground improvement method of this embodiment, under the water pressure during drilling, the valve body 4a is restricted from abutting (seating) on the valve seat 4b by the restricting member 5, and the valve 4 is maintained in an open state, so that the drilling process can be performed without hindrance. On the other hand, by applying a water pressure exceeding the water pressure during drilling to the valve body 4a, the restriction by the restricting member 5 is released, the valve body 4a abuts (seats) on the valve seat 4b, and the valve 4 is closed. Therefore, the water pressure acting on the valve body 4a can be increased by increasing the flow rate of the drilling water W supplied to the first flow path 11, etc., and the drilling water discharge port 32 can be blocked, so that there is no need to insert a steel ball from the ground surface through the rod to block the drilling water discharge port 32 as in the conventional technology of Patent Document 1, and it can be applied to a rod with a small diameter.

In addition, in the ground improvement device and ground improvement method of this embodiment, the compressed air injection nozzle 34 is provided with a sealing member 60 that is unsealed when pressure exceeding the water pressure during drilling is applied thereto, so that even if drilling water W is supplied to the first flow path 11 during drilling, it is possible to prevent the drilling water W from leaking out of the compressed air injection nozzle 34. On the other hand, after the drilling process is completed, the sealing member 60 can be unsealed by applying water pressure exceeding the water pressure during drilling to the sealing member 60, so that the original function of the compressed air injection nozzle can be performed thereafter.

Furthermore, in the sealing removal process, if drilling water W is supplied into the first flow path 11 and compressed air is supplied into the second flow path 12, and the compressed air is sprayed from the hardener spray nozzle 33 while the drilling water W with increased water pressure removes the seal of the sealing member 60, it is possible to prevent the drilling water W from flowing back into the monitor device 3 through the hardener spray nozzle 33.

2. Modifications Next, a modification of the present invention will be described with reference to Figures 5 and 6. Figure 5 is an enlarged cross-sectional view of the vicinity of the compressed air injection nozzle of the ground improvement device according to the modification. This modification relates to a modification of the sealing member, in which the sealing member 60 in the above embodiment is replaced with a sealing member 70 made of a different material and structure.

Specifically, in the above embodiment, the compressed air injection nozzle 34 is sealed by a sealing member 60 made of an annular band-shaped aluminum plate, but in this modified example, the compressed air injection nozzle 34 is sealed by a sealing member 70 made of a rubber plug (rubber plug). This rubber plug 70 (sealing member 70) has a truncated cone shape and has a through hole in the center. This through hole in the center is for inserting the hardener injection nozzle 33. Note that the inner circumferential surface of the compressed air injection nozzle 34 in the above embodiment and this modified example is formed into a truncated cone shape that gradually decreases in diameter toward the tip, so the outer shape of the rubber plug 70 is formed accordingly.

The rubber plug 70 thus formed is attached to the inside of the compressed air injection nozzle 34 to seal the nozzle 34. The seal can be released when pressure exceeding the water pressure during drilling is applied to it. Specifically, the seal is maintained under the water pressure during drilling, but is blown away when pressure exceeding the water pressure during drilling is applied to it. The purpose and function of the sealing member are the same as the sealing member 60 described above.

In addition, the sealing member 60 made of the aforementioned annular aluminum plate may be attached to the tip of the compressed air injection nozzle 34 in addition to the rubber plug 70. In other words, the sealing members 60 and 70 may be used together. Furthermore, the material of the sealing member 70 is not limited to rubber, and it may be made of plastic or wood.

Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to these embodiments. In the above embodiments, the restricting means is configured by the restricting member 5 consisting of a rod-shaped member 6 (vertical member) and a rod receiving member 7 (horizontal member), but the restricting means is not limited to this configuration.

In the above embodiment, the rod receiving member 7 (horizontal member) is configured as the weak part, but the part configured as the weak part is not limited to the rod receiving member 7 (horizontal member). The rod-shaped member 6 (vertical member) may be configured as the weak part, or both the rod receiving member 7 (horizontal member) and the rod-shaped member 6 (vertical member) may be configured as the weak part.

In the above embodiment, the vertical member (rod-shaped member 6) and the horizontal member (rod-receiving member 7) are constructed separately, and the lower end of the vertical member (rod-shaped member 6) is configured to abut against the horizontal member (rod-receiving member 7), but the two may be constructed integrally. When the two are constructed integrally, for example, they can be integrated by connecting the lower end of the rod-shaped member 6 (vertical member) to the rod-receiving member 7 (horizontal member).

3. Reference Example Next, a reference example of the present invention will be described with reference to the drawings. Figures 7 to 9 show a ground improvement device according to the reference example. Note that the same reference symbols are used for members that are the same as or correspond to the members of the above embodiment, and descriptions thereof will be omitted.

The ground improvement device according to the reference example is a ground improvement device equipped with a self-drilled hole type monitor device 103 that can be used in both the drilling process and the ground improvement process, similar to the ground improvement device according to the embodiment described above. As shown in FIG. 4(A) (since the overall configuration of the ground improvement device according to the reference example and the outline of each process are the same as those of the ground improvement device according to the embodiment, FIG. 4 is also cited for the reference example. However, when quoting FIG. 4 for the reference example, the reference number 3 is to be read as the reference number 103), the ground improvement device is equipped with a boring machine M installed on the ground, a rod 1, a swivel 2 provided at the base end (the upper end in the illustrated example) of the rod 1, and a self-drilled hole type monitor device 103 provided at the tip end (the lower end in the illustrated example) of the rod 1. The configurations of the boring machine M, the rod 1, and the swivel 2 in the reference example are the same as those in the embodiment.

As shown in Figures 7 and 8, the reference example of the self-drilling type monitoring device 103 has a metal crown (drilling bit) 31 and a drilling water outlet 32 at its lower end. In addition, in the middle of the monitoring device 103, a hardener injection nozzle 33 and a compressed air injection nozzle 34 surrounding it are concentrically arranged facing to the side.

Inside the monitor device 103, a first flow path 11 and a second flow path 12 are formed, which extend from the inside of the rod 1. Of these, the second flow path 12 extends further inside the monitor device 3 and is connected to the hardener injection nozzle 33.

On the other hand, inside the monitor device 103, the first flow path 11 branches into a third flow path 13 and a fourth flow path 14, with the third flow path 13 connected to the drilling water outlet 32 and the fourth flow path 14 connected to the compressed air injection nozzle 34. In other words, the first flow path 11 is connected to the drilling water outlet 32 via the third flow path 13, and is connected to the compressed air injection nozzle 34 via the fourth flow path 14. Although not shown, multiple third flow paths 13 are formed inside the monitor device 103, and these multiple third flow paths 13 merge downstream and are connected to the drilling water outlet 32.

The monitoring device 103 of the reference example is provided with a valve 104 that opens and closes the drilling water discharge port 32. As shown in FIG. 8, this valve 104 is provided with a valve body 104a made of a steel ball, a valve seat 104b provided above this valve body 104a, a compression coil spring 104c that urges the valve body (steel ball) 104a upward, and a restricting member 105 that restricts the valve body 104a from moving downward beyond a predetermined amount. In this reference example, the valve 104 is opened when the valve body 104a moves downward against the spring force of the compression coil spring 104c in response to water pressure during drilling, while the valve body is maintained in a closed state by the pressure of compressed air during ground improvement work.

The restricting member 105 in the reference example is configured as a cylindrical lower ball bearing member arranged vertically in the drilling water outlet passage 32a that communicates with the drilling water discharge port 32, unlike the restricting member 5 in the embodiment. The upper end 105a of this lower ball bearing member 105 is inserted into the inside of the compression coil spring 104c, and the annular convex rib 105b (Figure 9) formed on the cylindrical outer wall is fixed by fitting into the annular concave rib 32b (Figure 8) formed on the inner wall of the drilling water outlet passage 32a.

However, under normal conditions (i.e. when neither drilling water nor compressed air is acting), the upper end 105a of the lower ball receiving member (regulating member) 105 does not protrude from the top of the compression coil spring 104c, but remains inside it. As a result, the valve body 104a, which is biased upward by the compression coil spring 104c, and the upper end 105a of the lower ball receiving member 105 do not come into contact with each other, and are separated from each other. As a result, within this separated range, the valve body 104a can move downward, and there is no hindrance to the valve 104 opening when it receives water pressure during drilling.

In this reference example, on the other hand, the valve body 104a comes into contact with the upper end 105a of the lower ball bearing member 105 due to the action of water pressure during drilling. As a result, the valve 104 in the reference example opens when the valve body 104a moves downward in response to water pressure during drilling, but the presence of the lower ball bearing member 105 limits the degree of opening so that the valve does not open beyond a predetermined degree.

In this reference example, the compressed air injection nozzle 34 is sealed by a sealing member 60, as in the embodiment. The sealing member 60 in the reference example is also made of an annular aluminum plate, which is fixed around the compressed air injection nozzle 34 by screws (not shown). As in the embodiment, the sealing member 60 maintains the seal under the water pressure during drilling, but can be released by the action of a pressure that exceeds the water pressure during drilling. Note that the configuration of the sealing member is not limited to the above configuration, and may be one shown in Figures 7, 8 or 9, 10 of Patent Document 1, or the rubber plug 70 (sealing member 70) according to the above-mentioned modified example, and the hardener injection nozzle 33 is not sealed by a sealing member, as in the embodiment.

The ground improvement device of this reference example configured as described above is used as follows. The steps are explained below with reference to Figure 4. As mentioned above, the reference numeral 3 in Figure 4 should be read as reference numeral 103.

As shown in Fig. 4(A), a boring machine M is installed on the ground, and a rod 1 is attached to the boring machine M. A swivel 2 is attached to the upper end of the rod 1, and the above-mentioned self-drilling type monitoring device 103 is attached to the lower end thereof.

4(B), water or bentonite mud water is used as the drilling water W, and this drilling water W is supplied to the drilling water and compressed air supply port 2a of the swivel 2 communicating with the first flow path 11, and the drilling water W is discharged from the drilling water outlet 32 at the lower end of the monitor device 103, and the rod 1 is rotated by the boring machine M to drill to a predetermined depth. As described above, the valve body 104a moves downward against the spring force of the compression coil spring 104c due to the water pressure of the drilling water W during the drilling process, and the valve 104 opens, and the valve body 104a abuts against the upper end 105a of the lower ball bearing member 105, restricting further downward movement. At this time, the sealing member 60 is not released from the sealing. Therefore, the drilling water W is discharged only from the drilling water outlet 32 at the lower end of the monitor device 3. The mud generated by drilling is sucked to the ground and discharged by a sand pump 50.

As in the embodiment, during the drilling process, drilling water W may be supplied into the first flow path 11 and compressed air may be supplied into the second flow path 12 to eject drilling water W from the drilling water outlet 32 and eject compressed air from the hardener injection nozzle 33. As described above, since the hardener injection nozzle 33 is not sealed by the sealing member 60, it is possible to eject compressed air from the hardener injection nozzle 33 during the drilling process. In this way, ejecting compressed air from the hardener injection nozzle 33 during the drilling process can promote the discharge of mud generated by drilling to the ground surface.

<3> Sealing release process After the completion of the drilling process, when the supply flow rate of the drilling water W is increased, the further downward movement of the valve body 104a is restricted by the lower ball bearing member 105 (i.e., the opening of the valve 104 is limited), so the water pressure (internal pressure) of the drilling water W increases. This increase in water pressure releases the sealing of the sealing member 60. As in the case of the embodiment, when releasing the sealing of the sealing member 60, compressed air may be simultaneously supplied into the second flow path 12 and the compressed air may be sprayed from the hardener spray nozzle 33. In this way, by releasing the sealing of the sealing member 60 with the drilling water W with increased water pressure while spraying compressed air from the hardener spray nozzle 33, it is possible to prevent the drilling water W from flowing back into the monitor device 103 from the hardener spray nozzle 33.

<4> Test injection process After the sealing release process, water W0 for test injection is supplied to the hardener supply port 2b and compressed air A is supplied to the drilling water and compressed air supply port 2a to perform a test injection (Figure 4 (C)).

《5》Ground improvement process (preparation process)
If no abnormality is found, the water W0 for test injection is switched to the hardening material G, and compressed air A is injected from the compressed air injection nozzle 34, while the hardening material G is injected from the hardening material injection nozzle 33. Then, the rod 1 is pulled up while rotating according to a predetermined rotation angle, pulling speed, and rotation speed. As a result, a solidified body (improved body) 40 is created around the rod 1, and ground improvement is performed (FIG. 4(D)). In this ground improvement process, the valve 104 is kept in a closed state.

<6> Rod Removal and Hole Filling Process After the ground improvement process (construction process) is completed, the rod 1 is removed and the holes are filled. This completes the series of processes (FIG. 4(E)).

As described above, according to the ground improvement device and ground improvement method of the reference example, the water pressure during drilling acts on the valve body 104a, opening the valve 104, allowing the drilling process to be carried out without hindrance, while in the ground improvement process, the valve 104 remains closed, eliminating the need to insert steel balls from the ground surface through the rod to block the drilling water outlet 32, as in the conventional technology of Patent Document 1. For this reason, it can also be applied to rods with small diameters.

In addition, in the ground improvement device and ground improvement method of the reference example, the compressed air injection nozzle 34 is provided with a sealing member 60 that is released when a pressure exceeding the water pressure during drilling is applied thereto. Therefore, even if drilling water W is supplied to the first flow path 11 during drilling, it is possible to prevent the drilling water W from leaking out of the compressed air injection nozzle 34. On the other hand, after the completion of the drilling process, the seal can be released by applying water pressure exceeding the water pressure during drilling to the sealing member 60 by increasing the supply flow rate of the drilling water W, etc., so that the nozzle can thereafter perform its original function as a compressed air injection nozzle.

Furthermore, in the sealing removal process, if drilling water W is supplied into the first flow path 11 and compressed air is supplied into the second flow path 12, and the compressed air is sprayed from the hardener spray nozzle 33 while the drilling water W with increased water pressure removes the seal of the sealing member 60, it is possible to prevent the drilling water W from flowing back into the monitor device 3 through the hardener spray nozzle 33.

The main points of the reference example are summarized below.

[1] A self-drilling type monitoring device comprising a drilling water outlet, a hardener jet nozzle, a compressed air jet nozzle surrounding the hardener jet nozzle, a first flow path which is a common flow path for drilling water and compressed air, a second flow path for hardener, a third flow path connecting the first flow path and the drilling water outlet, a fourth flow path connecting the first flow path and the compressed air jet nozzle, and a valve for opening and closing the drilling water outlet,
The valve includes a valve body, a valve seat provided above the valve body, and a spring means for biasing the valve body upward,
This self-drilling type monitoring device is characterized in that the valve is configured to open when water pressure is applied during drilling, and to remain closed when compressed air pressure is applied during ground improvement.

[2] The valve is provided with a restricting means that contacts the valve body and restricts the downward movement of the valve body when a water pressure equal to or greater than the water pressure during drilling acts on the valve, thereby restricting the opening of the valve so that it does not open beyond a predetermined opening degree.
The self-drilling type monitoring device described in [1] is characterized in that the compressed air jet nozzle is provided with a sealing member that is released when pressure exceeding the water pressure during drilling is applied to it.

[3] The spring means is configured as a compression coil spring,
The regulating means is configured as a cylindrical member disposed in a vertical flow path from the valve body to the drilling water discharge port,
The self-drilling type monitoring device described in [2] is characterized in that the upper end of this cylindrical member is inserted into the interior of the compression coil spring from below and remains therein.

[4] A ground improvement method using the self-drilled hole type monitoring device described in [1],
a drilling step of supplying drilling water into the first flow path and rotating the monitor device while discharging the drilling water from the drilling water discharge port to drill a hole to a predetermined depth;
a valve closing step of stopping the supply of the drilling water and closing the valve;
a ground improvement process in which compressed air and a hardening material are supplied into the first and second flow paths, respectively, while the monitor device is rotated and raised, thereby injecting the compressed air and the hardening material from the compressed air injection nozzle and the hardening material injection nozzle, respectively, to improve the surrounding ground;
A ground improvement method comprising the steps of:

[5] A ground improvement method using the self-drilled hole type monitoring device described in [2],
a drilling step of supplying drilling water into the first flow path and rotating the monitor device while discharging the drilling water from the drilling water discharge port to drill a hole to a predetermined depth;
a sealing release step of increasing the water pressure of the drilling water to release the sealing of the compressed air jet nozzle by the sealing member;
a ground improvement process in which compressed air and a hardening material are supplied into the first and second flow paths, respectively, while the monitor device is rotated and raised, thereby injecting the compressed air and the hardening material from the compressed air injection nozzle and the hardening material injection nozzle, respectively, to improve the surrounding ground;
A ground improvement method comprising the steps of:

[6] The ground improvement method described in [5], characterized in that in the unsealing step, drilling water is supplied into the first flow path and compressed air is supplied into the second flow path, and the sealing of the sealing member is unsealed by the water pressure of the drilling water supplied into the first flow path while the compressed air is sprayed from the hardener spray nozzle.

1...Rod, 2...Swivel, 2a...Drilling water and compressed air supply port, 2b...Hardening material supply port, 3...Self-drilling type monitor device (embodiment), 4...Valve, 4a...Steel ball (valve body), 4b...Valve seat, 4c...Compression coil spring, 5...Regulating member, 6...Rod-shaped member, 6a...Rod main body, 6b...Sway prevention portion, 7...Rod receiving member, 7a...Threaded hole, 11...First flow path, 12...Second flow path, 13...Third flow path, 14...Fourth flow path, 31...Metal crown (drilling bit), 32...Drilling water outlet, 32a...Outlet passage, 32b...Annular groove, 33...Hardening Material injection nozzle, 34... compressed air injection nozzle, 40... solidified body (improved body), 50... sand pump, 60... sealing member (aluminum plate), 70... sealing member (rubber plug), 103... self-drilling type monitor device (reference example), 104... valve, 104a... steel ball (valve body), 104b... valve seat, 104c... compression coil spring, 105... lower ball bearing member (regulating member), 105a... upper end (of the lower ball bearing member), 105b... ring-shaped ridge, A... compressed air, G... hardening material, M... boring machine, W... drilling water, W0... water for test injection

Claims (7)

A self-drilling type monitor device comprising: a drilling water outlet, a hardener jet nozzle, a compressed air jet nozzle surrounding the hardener jet nozzle, a first flow path which is a common flow path for drilling water and compressed air, a second flow path for hardener, a third flow path connecting the first flow path and the drilling water outlet, a fourth flow path connecting the first flow path and the compressed air jet nozzle, and a valve for opening and closing the drilling water outlet,
The valve includes a valve body, a valve seat provided below the valve body, spring means for biasing the valve body downward, and restricting means for restricting downward movement of the valve body to prevent it from contacting the valve seat,
A self-drilling type monitoring device characterized in that the regulating means is configured to release the restriction when water pressure exceeding the water pressure during drilling acts on the valve body. At least a part of the regulating means is configured as a fragile part that bends or breaks when water pressure exceeding the water pressure during drilling acts on the valve body,
2. The self-drilling type monitoring device according to claim 1, characterized in that the restriction by the restricting means is released when the weak portion is bent or broken. The self-drilling type monitoring device according to claim 2, characterized in that the regulating means comprises a horizontal member extending horizontally across the vertical flow path from the valve body to the drilling water outlet, and a vertical member extending upward from the horizontal member toward the valve body, the horizontal member being configured as the weak part. The self-drilling type monitoring device according to claim 1, characterized in that the compressed air injection nozzle is provided with a sealing member that is released when pressure exceeding the water pressure during drilling acts on the nozzle. A ground improvement method using the self-drilled hole type monitoring device according to claim 1,
a drilling step of supplying drilling water into the first flow path and rotating the monitor device while discharging the drilling water from the drilling water discharge port to drill a hole to a predetermined depth;
a valve closing step of increasing the water pressure of the drilling water to release the restriction by the restriction means and close the valve;
a ground improvement process in which compressed air and a hardening material are supplied into the first and second flow paths, respectively, while the monitor device is rotated and raised, thereby injecting the compressed air and the hardening material from the compressed air injection nozzle and the hardening material injection nozzle, respectively, to improve the surrounding ground;
A ground improvement method comprising the steps of: A ground improvement method using the self-drilled hole type monitoring device according to claim 4,
a drilling step of supplying drilling water into the first flow path and rotating the monitor device while discharging the drilling water from the drilling water discharge port to drill a hole to a predetermined depth;
a valve closing step of increasing the water pressure of the drilling water to release the restriction by the restriction means and close the valve;
a sealing release step of releasing the sealing of the compressed air jet nozzle by the sealing member using the increased water pressure of the drilling water;
a ground improvement process in which compressed air and a hardening material are supplied into the first and second flow paths, respectively, while the monitor device is rotated and raised, thereby injecting the compressed air and the hardening material from the compressed air injection nozzle and the hardening material injection nozzle, respectively, to improve the surrounding ground;
A ground improvement method comprising the steps of: The ground improvement method according to claim 6, characterized in that in the unsealing step, drilling water is supplied into the first flow path and compressed air is supplied into the second flow path, and the sealing of the sealing member is unsealed by the water pressure of the drilling water supplied into the first flow path while the compressed air is sprayed from the hardener spray nozzle.