JP2020186525A - Drilling method and drilling device - Google Patents

Abstract

To provide a drilling method capable of suppressing bending of a rod during drilling and maintaining vertical accuracy of drilling.SOLUTION: In a drilling method for drilling the ground 42 by rotating a rod 34 to which a bit 32 is attached, the steps of detecting the axial force generated in the rod 34 during the ground drilling, pulling up the rod 34 to separate the bit 32 from a hole bottom 44B of a hole 44 before the axial force reaches the preset limit axial force and then lowering the rod 34 to drill the ground 42 are repeated.SELECTED DRAWING: Figure 1

Description

The present invention relates to a drilling method and a drilling device.

There are a drilling method and a drilling device for drilling holes in the ground or the like by rotating a rod to which a bit is attached (see, for example, Patent Document 1).
In the drilling method described in Patent Document 1, the rotary drive device is moved downward by a lower feed amount shorter than the total stroke while rotating the bit together with the rod, and then the raise feed amount shorter than the lower feed amount. The hole is drilled while repeating the operation of moving upward.

Japanese Unexamined Patent Publication No. 9-217581

Further, in the past, in general, drilling is performed by controlling only the rotation speed of the bit and the drilling speed, and it may not be possible to suppress the bending of the rod during drilling, so that the vertical accuracy of drilling is maintained. It may not be possible.

In view of the above facts, an object of the present invention is to provide a drilling method and a drilling device capable of suppressing bending of a rod during drilling and maintaining vertical accuracy of drilling.

The invention according to claim 1 is a drilling method in which a rod to which a bit is attached is rotated to drill a hole in the ground, and an axial force generated in the rod is detected during the drilling of the ground, and the axial force is previously determined. Before reaching the set limit axial force, the rod is pulled up to separate the bit from the hole bottom, and then the rod is lowered to repeat the step of drilling the ground.

In the drilling method according to claim 1, the rod to which the bit is attached is rotated to drill the ground. Then, during ground drilling, the axial force generated in the rod is detected, and before the detected axial force reaches the preset limit axial force, the rod is pulled up to separate the bit from the hole bottom, and then the rod is lowered. The step of drilling the ground is repeated to proceed with drilling.

Here, the "marginal axial force" will be described.
When the rod is stood vertically, the weight of the rod acts as an axial force on the lower end of the rod. This axial force increases in proportion to the weight (length) of the rod.

The critical axial force is the axial force that acts on the lower end of the rod to bend the rod to the allowable gradient of the design.
By repeating the steps of pulling up the rod before the axial force reaches the limit axial force, separating the bit from the bottom of the hole, and then lowering the rod to drill the ground, bending of the rod is suppressed to the desired depth. Drilling can proceed while maintaining vertical accuracy.

The invention according to claim 2 pulls up the rod in the hole drilling method according to claim 1 when the axial force reaches 80 to 90% of the limit axial force.

In the drilling method of claim 2, since the upper limit of the axial force during drilling is suppressed to 90% of the limit axial force, bending of the rod can be suppressed even if an unexpected axial force acts on the rod.
When the lower limit of the axial force during drilling is set to less than 80% of the limit axial force, the number of repetitions of vertical movement increases and the drilling time becomes long.
Therefore, when the axial force during drilling reaches 80 to 90% of the critical axial force, the rod is pulled up so that the drilling can be performed efficiently while maintaining the vertical accuracy. ..

The drilling device according to claim 3 includes a rotary drive device that rotates a rod to which a bit is attached, a vertical drive device that moves the rotary drive device up and down in a suspended state, the bit, and the rod. The suspension load sensor that detects the suspension load of the rotational drive device and the axial force that acts on the rod when the ground is drilled with the bit from the detected suspension load are obtained, and the obtained axial force is obtained. Moves the rotary drive device upward to separate the bit from the hole bottom, and then moves the rotary drive device downward to drill a hole in the ground before reaching the preset limit axial force of the rod. It has a control device that controls the vertical drive device so as to repeat the above.

In the hole drilling device according to claim 3, the rod to which the bit is attached is rotated by the rotary drive device, and the rotary drive device is lowered by the vertical drive device, so that the ground can be drilled by the rotating bit.

The suspension load sensor detects the suspension load of the rotary drive device to which the bit and the rod are attached.

The control device obtains the axial force acting on the lower end of the rod when drilling the ground with a bit from the suspension load detected by the load sensor, and before the obtained axial force reaches the preset limit axial force of the rod. The rotary drive device is moved upward to separate the bit from the bottom of the hole, and then the rotary drive device is moved downward to repeat the step of drilling the ground, and the vertical drive device is controlled to advance the drilling.

As described above, in the drilling device according to claim 3, the drilling is advanced so as to pull up the rod before the axial force reaches the limit axial force, and after the bit is separated from the hole bottom, the rod is lowered to lower the ground. The step of drilling is repeated, the bending of the rod is suppressed, and the drilling can be advanced while maintaining the vertical accuracy to a desired depth.

According to the drilling method of the present invention, bending of the rod during drilling can be suppressed and vertical accuracy of drilling can be maintained.
Further, according to the drilling device of the present invention, bending of the rod during drilling can be suppressed and the vertical accuracy of drilling can be maintained.

It is a side view which shows the schematic structure of the drilling apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the control system. (A) is a side view showing the vicinity of the lower end of the rod bent by the weight of the rod, (B) is an explanatory view explaining the gradient of the lower end of the rod, and (C) is a bit attached to the bent rod. It is sectional drawing which shows the ground which was drilled. It is a graph which shows the relationship between the depth of drilling and the elapsed time when drilling by the conventional drilling method. It is a graph which showed the relationship between the depth of drilling and the axial force of a rod at the time of drilling by the conventional drilling method. It is a graph which shows the relationship between the depth of drilling and the displacement amount of the lower end of a rod at the time of drilling by the conventional drilling method. It is a graph which shows the relationship between the depth of drilling and the elapsed time at the time of performing the drilling method which concerns on Example of this invention. It is an enlarged view which enlarged a part of the graph shown in FIG. 7. It is a graph which showed the relationship between the axial force of a rod and the depth of drilling at the time of performing the drilling method which concerns on Example of this invention. It is a graph which shows the relationship between the depth of drilling and the displacement amount of the lower end of a rod at the time of performing the drilling method which concerns on Example of this invention.

Hereinafter, the drilling device 10 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 3.

As shown in FIG. 1, in the drilling device 10 of the present embodiment, the mast 14 is tiltably supported by the base heavy machine 12 (in FIG. 1, a state in which the mast 14 is vertically supported is illustrated. There is.).

A top sheave block 16 is attached to the upper end of the mast 14, and a sheave block 20 rotatably provided with a sheave (moving pulley) 20A is suspended from a wire 18 hanging from the top sheave block 16. The wire 18 can be wound around the winch 22 installed on the base heavy machine 12.

A rotary drive device 28 is suspended below the sheave block 20.
The rotary drive device 28 slides along a guide rail 24 supported along the mast 14.
The rotation drive device 28 includes a motor 30, and a rod 34 to which a bit 32 is attached to a tip (lower end) is attached to the rotation shaft of the motor 30. As an example, the rod 34 is made of a steel pipe or the like.

As shown in FIGS. 1 and 2, the winch 22 and the rotary drive device 28 are driven by a control device 36 provided on the base heavy machine 12. Further, the control device 36 is input by a load sensor 26, which will be described later, an input device 38 for inputting conditions related to drilling, an operation lever 39 for performing various operations of the drilling device 10, and an input device 38. A display device 40 or the like that displays conditions and various states of the drilling device 10 is connected.

As shown in FIG. 1, the sheave block 20 is provided with a load sensor 26, and the load sensor 26 can measure the combined load of the rotary drive device 28, the rod 34, and the bit 32. There is. The load measurement data measured by the load sensor 26 is transmitted to the control device 36.

(Preparation before drilling)
As shown in FIG. 3A, when the rod 34 is erected vertically on the ground 42, the lower end side bends slightly due to its own weight (Note that in FIG. 3A, the bending of the rod 34 is emphasized and shown. It has been.).

In this way, when the lower end side of the rod 34 is bent by the weight of the rod 34, the tangent TL of the axis CL of the rod 34 passing through the lower end of the rod 34 is inclined with respect to the vertical line VL, and the tangent line TL becomes the vertical line VL. On the other hand, it has a gradient (see FIG. 3B. B / A. A is a vertical distance and B is a horizontal distance).

As shown in FIG. 3C, when the ground 42 is drilled with the bit 32 attached to the rod 34 whose lower end side is bent, the bit 32 drills the ground 42 along the axis CL of the bent rod 34. .. Therefore, the drilled hole 44 is inclined with respect to the vertical straight line VL, and the vertical accuracy of the hole 44 deteriorates.

The gradient of the tangent TL at the lower end of the rod 34 during drilling and the gradient of the drilled hole 44 are in a corresponding relationship. Therefore, in order to maintain the vertical accuracy of the hole 44, it is first necessary to keep it within the maximum value of the gradient allowed for the hole 44 to be drilled (which can be said to be a design tolerance).

In order to make the gradient (maximum value) of the actually drilled hole 44 less than the maximum value of the gradient allowed for the hole 44, the value of the gradient of the tangent TL at the lower end of the rod 34 during drilling is set. , It is necessary to drill holes so that the maximum value of the gradient allowed in the holes 44 is not reached.

Since it is practically difficult to grasp the gradient of the tangent line TL at the lower end of the rod 34 during drilling inside the ground 42, in the present embodiment, the tangent line TL at the lower end of the rod 34 is as follows. Indirectly grasp the gradient.

First, as an example, using a method such as simulation, the lower end of the rod 34 when the rod 34 used for drilling is erected vertically reproduces the side bending (due to its own weight), and the axis line at the lower end of the rod 34 with respect to the vertical line. The gradient of the tangent TL of CL (see FIG. 3B) is obtained. When performing a simulation using a computer, various conditions such as the length, diameter, thickness, and material of the rod 34 are input to the computer (note that the length, diameter, thickness, and material of the rod 34 are determined. , The weight (own weight) of the rod 34 can be obtained by calculation).

Next, in the above simulation, the axial force AF (which can also be said to be the pressing force from the rod 34 acting on the ground 42) applied to the lower end of the rod 34 is gradually increased to obtain the axial line CL at the lower end of the rod 34 with respect to the vertical line VL. The gradient of the tangent line TL is obtained, and the axial force when the gradient value becomes the same as the maximum value of the gradient value allowed in the hole 44 described above (hereinafter referred to as the limit axial force AFmax) is obtained.

Next, an axial force having a value lower than the limit axial force AFmax (hereinafter referred to as an upper limit axial force AFU limit (Upper limit) at the time of drilling. The user decides in consideration of various conditions) is set. As an example, the upper limit axial force AFUlimit at the time of drilling is preferably an arbitrary axial force within the range of 80 to 90% of the limit axial force AFmax, but in some cases, 80 to 90% of the limit axial force AFmax. It may be out of the range.
Then, the set value of the upper limit axial force AFU limit at the time of drilling is stored in the control device 36.

When actually drilling the ground 42, the wire 18 suspends the sheave block 20, the rotation drive device 28, the rod 34, and the bit 32, and the load sensor 26 uses the rotation drive device 28 and the rod. The combined load of 34 and the bit 32 is measured. In a state where the bit 32 is in contact with the ground 42 and the member of the sheave block 20 or less is not suspended by the wire 18 (self-supporting state), the load of the rotary drive device 28 is applied to the lower end of the rod 34 by the weight of the rod 34. Then, the load of the sheave block 20 acts. Therefore, the control device 36 controls the winch 22 to control the lifting load so that the axial force AF acting on the lower end of the rod 34 does not reach the limit axial force AFmax.

(Drilling procedure)
Next, a procedure for actually excavating the ground 42 with the bit 32 will be described.
(1) A rod 34 to which the bit 32 is attached is placed above the planned drilling position of the ground 42, and then the bit 32 is rotationally driven together with the rod 34, and the wire 18 is sent out by the winch 22 to lower the sheave block 20. ..

When the bit 32 comes into contact with the ground 42, the combined weight of the sheave block 20, the rotary drive device 28, and the rod 34 acts on the tip of the bit 32. In other words, the ground 42 receives this weight from the bit 32 and is drilled.
Then, during drilling, the control device 36 constantly monitors the load measurement data from the load sensor 26, that is, the value of the axial force AF that actually acts on the lower end of the rod 34 during drilling of the ground 42. The feeding of the wire 18 by the winch 22 is controlled so as to be less than the limit axial force AFmax.

(2) Then, when the axial force AF acting on the lower end of the rod 34 reaches the upper limit axial force AFU limit at the time of drilling stored in the control device 36, the control device 36 reverses the winch 22 and winds the wire 18. The bit 32 is separated upward from the hole bottom 44B of the drilled hole 44. As a result, the axial force AF does not act on the rod 34 (strictly speaking, a tensile load acts on the rod 34 due to the weight of the rod 34 and the weight of the bit 32).

If the axial force AF acting on the rod 34 does not reach the upper limit axial force AFU limit at the time of drilling during drilling, drilling may be continued.

In this way, when the axial force AF acting on the rod 34 reaches the upper limit axial force AFU limit at the time of drilling, that is, by pulling up the rod 34 before reaching the limit axial force AFmax, the rod is drilled during drilling. It is suppressed that the value of the gradient of the tangent line of the axis at the lower end of 34 becomes larger than the preset allowable gradient.

Further, even if the rod 34 is drilled while causing a slight bend (however, it is smaller than a preset allowable gradient), the bit 32 is separated from the hole bottom 44B of the hole 44 by separating the bit 32 from the hole bottom 44B of the hole 44. The axial force AF acting on the rod 34 becomes zero, and the rod 34 is returned to a straight line along the vertical direction.

(4) After separating the bit 32 from the hole bottom 44B of the hole 44 in this way, the wire 18 is sent out again, the hole is drilled by the bit 32, and the axial force AF acting on the rod 34 is a control device. When the upper limit axial force at the time of drilling AFU limit stored in 36 is reached, the wire 18 is wound as described above, and the bit 32 is separated upward from the hole bottom 44B of the drilled hole 44 by a predetermined distance, and so on. Continue drilling to a preset depth.

In this way, in the drilling method of the present embodiment, the rod 34 is pulled up before the axial force AF acting on the rod 34 reaches the preset limit axial force AFmax, and the bit 32 is drilled from the hole bottom of 44. After releasing, the step of lowering the rod 34 and drilling the ground is repeated to advance the drilling to a desired depth.

By doing so, the gradient on the lower end side of the rod 34 is suppressed from reaching a preset allowable gradient, and the vertical accuracy of the drilling can be maintained.

(5) If the hole 44 to be drilled is deep, a rod 34 is added to drill the hole. When a new rod 34 is added to perform hole drilling, the weight of the entire rod changes. Therefore, the limit axial force AFmax is calculated again to obtain the hole, and the hole drilling is performed in the same manner as in the above-described step.

In the drilling method of the present embodiment, the upper limit of the axial force AF during drilling is suppressed to 90% or less of the limit axial force AFmax, so that the rod 34 bends even if an unexpected axial force acts on the rod 34. Can be suppressed. If the lower limit of the axial force AF during drilling is set to less than 80% of the limit axial force AFmax, the number of repetitions of vertical movement increases and the drilling time becomes longer. Therefore, when the axial force AF during drilling reaches 80 to 90% of the limit axial force AFmax, the rod 34 is pulled up to efficiently drill holes while maintaining vertical accuracy. be able to.

Further, there is no limit to the distance that the bit 32 is separated from the hole bottom 44B of the hole 44, but if the distance is too long, the winding time of the wire 18 becomes long, and as a result, the drilling is completed. Working time becomes longer.

(Test example)
The test results of the case where the hole is drilled by the conventional drilling method and the case where the hole is drilled by the drilling method according to the embodiment of the present invention are shown below.

(Conventional example)
In the drilling method according to the conventional example, the sheave block is continuously lowered until the bit reaches a depth of 20 m to drill a hole. The drilling device (construction machine) described in the above embodiment was used for drilling, but the drilling method is different from that of the embodiment as described above. In addition, since the length of the rod was insufficient during drilling, the sheave block was once pulled up at a depth of 20 m (1 hour before the start of drilling), the rod was replenished, and drilling was restarted. The holes were drilled to a depth of 40 m.

FIG. 4 shows a graph showing the relationship between the elapsed time and the depth when a hole having a depth of 40 m is drilled by the drilling method according to the conventional example.

FIG. 5 shows a graph showing the relationship between the axial force acting on the rod (denoted as the rod axial force in the graph) and the depth in the conventional example in which a hole of 40 m is drilled. As shown in the graph of FIG. 5, in the conventional drilling method, the axial force AF of the rod exceeds the limit axial force AFmax after the depth of 20 m.

Further, a hole with a depth of 20 m and a hole with a depth of 40 m were drilled, and the relationship between the depth and the displacement amount of the lower end of the rod was investigated. FIG. 6 shows a graph showing the relationship between the depth and the displacement amount of the lower end of the rod. Here, the displacement amount is described with the reference position value set on the ground surface as zero and the displacement amount (maximum value) in the horizontal direction from the reference value position as the displacement amount.
The displacement amount is obtained by installing a gyro sensor on the lower end side inside the rod and measuring the position on the lower end side of the rod. The lines "1/200" and "1/300" in the figure indicate the slope of the hole.
In this test example, as an example, the goal is to reduce the maximum value of the hole gradient (design tolerance) to 1/300 or less.
As shown in the graph of FIG. 6, according to the conventional drilling method, in the hole drilled 40 m, the gradient exceeds 1/300 after the depth of 30 m, and the vertical accuracy deteriorates as the depth increases, and the depth becomes deeper. It can be seen that the gradient reaches 1/200 at around 40 m.

(Example)
FIG. 7 shows a graph showing the relationship between the elapsed time and the depth when a hole having a depth of 40 m is drilled by the drilling method according to the embodiment of the present invention.

In the drilling method according to the embodiment, since the axial force AF acting on the rod did not reach the upper limit axial force AFU limit at the time of drilling up to a depth of 20 m, the sheave block was continuously lowered to drill holes.
In addition, since the length of the rod was insufficient during drilling, the sheave block was once pulled up at a depth of 20 m (1 hour before the start of drilling), the rod was replenished, and drilling was restarted. Immediately after resuming drilling, the axial force AF acting on the rod may reach the upper limit axial force AFU limit during drilling. Therefore, when the axial force AF reaches the upper limit axial force AFU limit during drilling, the drilling is performed. The step of stopping once, pulling up the sheave block by a predetermined distance, and then advancing the drilling was repeated a plurality of times to drill a hole to a depth of 40 m.

Note that FIG. 8 is an enlarged view of a part of the graph line showing the relationship between the depth after the depth of 20 m and the elapsed time in this embodiment. The graph line in FIG. 8 shows that the step of drilling 1 m and pulling up 50 cm is repeated a plurality of times.

FIG. 9 shows a graph showing the relationship between the axial force AF acting on the rod and the depth in this embodiment in which a hole of 40 m is drilled. As shown in the graph of FIG. 9, in the drilling method of this embodiment, it can be seen that the axial force AF of the rod does not reach the limit axial force AFmax until the drilling is completed.

Similar to the conventional example, a hole with a depth of 20 m and a hole with a depth of 40 m were drilled, and the relationship between the depth and the displacement amount of the lower end of the rod was investigated.
As shown in the graph of FIG. 10, according to the drilling direction of this embodiment, the gradient of the drilled hole is less than 1/300, and the maximum value is suppressed to about 1/200, which is compared with the conventional example. It can be seen that high vertical accuracy is obtained.

[Other Embodiments]
Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

In the above embodiment, the limit axial force AFmax is obtained by simulation, but the limit axial force AFmax can also be obtained by using the actual rod 34. Hereinafter, an example of a method for obtaining the limit axial force AFmax will be described.
(1) The bending of the rod 34 with respect to the vertical direction, and more specifically, the gradient of the axis (or the outer surface of the rod) CL of the rod 34 at the lower end of the rod 34 with respect to the vertical line VL can be measured (see FIG. 3B). The gradient measuring device is installed on the ground 42 or a flat plate placed on the ground 42.
(2) After bringing the tip (lower end) of the bit 32 of the rod 34 suspended by the drilling device 10 into contact with the ground 42 (or flat plate), the wire 18 is sent out, the load is measured by the load sensor 26, and the rod 34 is measured. Simultaneously measure the gradient on the lower end side of the (measurement by continuously changing the load or changing the load in steps with a predetermined value).
When the tip of the bit 32 is away from the ground 42 (or flat plate), the load measured by the load sensor 26 is the weight obtained by adding the weight of the rotary drive device 28, the weight of the rod 34, and the weight of the bit 32. It becomes. Then, when the tip of the bit 32 comes into contact with the ground 42 and then the wire 18 is continuously fed, these weights gradually act on the ground 42, and the load measured by the load sensor 26 decreases accordingly. When all of these weights act on the ground 42, tension does not act on the wire 18 (the wire 18 loosens), and the load measured by the load sensor 26 becomes zero.
(3) Next, the axial force AF is obtained by observing the suspended load with the load sensor 26, and the relationship between the axial force AF and the gradient is grasped by an experiment using an actual object to correspond to the maximum allowable gradient. The axial force to be applied, that is, the limit axial force AFmax can be obtained.

10 Drilling device 18 Wire (upper and lower drive device)
22 winch (vertical drive)
26 Suspended load sensor 28 Rotational drive device 32-bit 34 Rod 36 Control device 42 Ground 44 Hole 44B Hole bottom

Claims (3)

It is a drilling method that drills the ground by rotating the rod to which the bit is attached.
Axial force generated in the rod during ground drilling is detected, and the rod is pulled up to separate the bit from the bottom of the hole before the axial force reaches a preset limit axial force, and then the rod is lowered. A drilling method that repeats the steps of drilling the ground. The hole drilling method according to claim 1, wherein the rod is pulled up when the axial force reaches 80 to 90% of the limit axial force. A rotary drive that rotates the rod with the bit attached,
A vertical drive device that moves the rotary drive device up and down in a suspended state,
A suspension load sensor that detects the suspension load of the rotation drive device to which the bit and the rod are attached, and
From the detected suspension load, the axial force acting on the rod when the ground is drilled with the bit is obtained, and the rotational drive is performed before the obtained axial force reaches the preset limit axial force of the rod. A control device that controls the vertical drive device so as to repeat the steps of moving the device upward to separate the bit from the bottom of the hole, and then moving the rotary drive device downward to drill a hole in the ground.
Drilling device with.