JPH0886092A - Concrete detector and top-end position sensor using concrete detector - Google Patents

Abstract

PURPOSE: To sense the position of the top end of concrete in a labor saving manner. CONSTITUTION: Two electrodes 11a, 11a are mounted at the tip end of a vertically movable cable 10 through a winch 12, and a resistance-change measuring circuit 13 with an AC bridge is connected for detecting the change of electric impedance Z between the two electrodes 11a, 11a. A comparison decision circuit 25 capable of outputting a concrete detecting signal S2 when concrete 3 is brought into contact with the electrodes 11a, 11a and voltage (e) between two terminals alters is installed, and an encoder 17 and an electrode-place sensing section 24 are set up so as to be able to obtain the places of the two electrodes 11a, 11a at the time of the output of the signal S2 in a type that the quantity of driving of the winch 12 is detected. A top-end height arithmetic section 23 for arithmetically operating the place of a top end 3a on the basis of the positions of the two electrodes 11a, 11a is fitted previously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete detector suitable for casting concrete for constructing cast-in-place piles, continuous underground walls, etc. and a crown position detecting device using the concrete detector. .

[0002]

2. Description of the Related Art FIG. 6 is a view showing a state where concrete placing work is performed while detecting the top position of concrete by a conventional method. Generally, when constructing a cast-in-place pile or an underground continuous wall from cast-in-place concrete, first, as shown in FIG.
While holding at, dig the vertical hole 30. And stabilizing liquid 31
Reinforcing bars are built in the vertical holes 30 held by, and concrete 33 is placed therein using a tremie pipe 32. By the way, when pouring concrete 33, if the length by which the tremie pipe 32 is inserted into the concrete 33, that is, the rooting length D1 is too long, the flow of the concrete 33 deteriorates, and conversely if it is too short, the concrete 33 stabilizes. The liquid 31 may be mixed. Furthermore, when the tremie pipe 32 is separated from the top end 33a of the concrete 33 and the rooting is lost, the concrete 33 is cast into the stabilizing solution 31 and a good concrete structure can be constructed. Absent. Therefore, conventionally, at the time of pouring concrete, a weight 36 is attached to the tip of the tape-shaped measure 35, and a feeling of hitting the top end 33a of the concrete 33 on which the weight 36 is placed is detected, and the top end 33a is detected. The position D is detected and the distance D2 to the top 33a is sequentially detected by reading the scale of the measure 35 at this time. Then, by continuously recording the detected value and making it correspond to the pulling speed of the tremie pipe 32, the concrete pouring was managed so as to keep the rooting length D1 at a predetermined proper value. .

[0003]

However, since the position of the top end 33a of the concrete 33 is detected by the human touch, the work is always occupied by one worker. become. Further, a recorder is required to write down the detected position of the top end 33a. Therefore, detecting the position of the top end 33a of the concrete 33 during casting is a work that cannot be omitted, but it requires a great deal of labor, and labor saving has been demanded. Therefore, the present invention, in view of the above circumstances,
The present invention provides a concrete detector capable of easily detecting the presence or absence of concrete to detect the top end position at any time in a labor-saving manner, and a top end position detecting device using the same.

[0004]

That is, the invention according to claim 1 of the present invention has two electrodes (11a, 11a) that can be installed in a concrete placing space (2), and
To the two electrodes (11a, 11a)
a, 11a), a detection circuit (13) for detecting a change in electrical impedance (Z) is connected, and the detection circuit (1) is connected.
Based on the output signal (S1) output from 3), it is determined whether or not the two electrodes (11a, 11a) are in the cast concrete (3), and the concrete detection signal (S2) The concrete detector (9) is constructed by connecting the determination means (25) for outputting The invention according to claim 2 of the present invention is the concrete detector (9) according to claim 1, wherein the detection circuit (13) has an electrical resistance (R4) between the two electrodes (11a, 11a). ) Is one of the resistors, and an output terminal (13) for outputting the output signal to the judging means (25) based on the voltage (e) between the two terminals of the AC bridge (13a). 13d). Further, the invention according to claim 3 of the present invention is the concrete detector (9) according to claim 1, wherein the two electrodes (11a, 11a) are provided at the tip of a cable (10) which can be wound and wound. Put on the above two electrodes (11a, 1
1a) is provided with a drive means (12) for moving up and down through the cable (10), and the two electrodes (11)
a, 11a) is provided and position detecting means (17, 24) capable of outputting as an electrode position signal (S4) is provided,
Composed. Further, among the present inventions, the invention according to claim 4 is the concrete detector (9) according to claim 3, when the concrete detection signal (S2) output from the judging means (25) is changed. A ceiling for calculating the position of the top end (3a) of the cast concrete (3) in the concrete placing space (2) from the electrode position signal (S4) output from the position detecting means (17, 24). The top position detecting device (7) is configured by providing the end position calculating means (23). The numbers in parentheses () indicate the corresponding elements in the drawings for convenience, and therefore the present description is not limited to the description in the drawings. The same applies to the following action columns.

[0005]

With the above construction, the invention according to claim 1 of the present invention is such that when two electrodes (11a, 11a) come into contact with concrete (3), the two electrodes (11a, 11a)
Since the electrical impedance (Z) between a) changes and the output signal (S1) output from the detection circuit (13) changes, the determination means (25) at this time makes the determination means (25) the two electrodes (1).
It is determined that concrete (3) is present between 1a and 11a), and the concrete detection signal (S2) is output. The invention according to claim 2 of the present invention is
The judging means (25) is provided with 2 of the AC bridge (13a).
It acts to determine whether or not there is concrete (3) based on the change in voltage (e) generated between the terminals. In the invention according to claim 3 of the present invention, the driving means (1
While the two electrodes (11a, 11a) are driven to move up and down by 2), the determination means (25) has two electrodes (1
1a, 11a) between the two electrodes (11a, 1a)
The position detecting means (17, 24) detects the position of 1a). In the invention according to claim 4 of the present invention, the two electrodes (11a, 11a) attached to the tip of the cable (10) are installed in the concrete pouring space (2).
While moving up and down, the determination means (25) moves the concrete (3) between the two electrodes (11a, 11a).
When it is determined that there is, the top end position calculation means (23) operates to detect the top end (3a) position of the concrete (3).

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a state in which an embodiment of a top end position detecting device using a concrete detector according to the present invention is applied to the construction of a pile, and FIG. 2 is a concrete detection in the concrete detector shown in FIG. FIG. 3 is a diagram showing the principle, FIG. 3 is a diagram showing an example of a display state of the display unit in the top position detecting device shown in FIG. 1, and FIGS. 4 to 5 are concrete detectors shown in FIG. 1 for construction of an underground continuous wall. It is a figure which shows the applied state.

The construction site 1 for cast-in-place piles is shown in FIG.
As shown in FIG. 2, the vertical hole 2 dug down into the ground from the ground 39 a is formed as a concrete pouring space to a predetermined depth, and the concrete 3 is provided below the vertical hole 2 from the bottom 2 a of the vertical hole 2. It is being launched up to the height L1 and is placed and placed in an amount corresponding to the input amount. The vertical hole 2 above the concrete 3 is filled with a stabilizing solution 5 such as bentonite liquid or fresh water up to the vicinity of the mouth of the vertical hole 2, and the vertical hole 2 is provided with a tremie pipe 6 and a concrete supply port 6a thereof. Is placed on the ground, and the concrete discharge port 6b is provided by being submerged from the top end 3a by a predetermined rooting depth L2 into the concrete 3 being placed.

As shown in FIG. 1, the construction point 1 is provided with a top position detecting device 7, and the top position detecting device 7 has a concrete detector 9. The concrete detector 9 has a cable 10 which is drawn out into the vertical hole 2 so as to be freely wound and wound. In the cable 10, two-core conductive wires 11 and 11 are provided. Electrodes 11a and 11a are attached to the tip of the cable 10 such that the lower ends of the conductors 11 and 11 are exposed to the outside of the cable 10 by gold plating or the like, and the electrodes 11a and 11a are vertically movable through the cable 10. While the cable 1
The base end side of 0 is wound around and supported by the drum 12a of the winch 12. In addition, the two electrodes 11a of the cable 10,
A resistance fluctuation measuring circuit 13 is connected to 11a as a detection circuit for detecting a change in the electrical impedance Z between the two electrodes 11a, 11a.
A detection control device 15 is connected to 3.

The resistance fluctuation measuring circuit 13 has an AC bridge 13a as shown in FIG.
3a is a shape in which a diagonal line of a bridge formed by three resistors R1, R2, and R3 that do not change and a resistor R4 that is variable by a change in the electrical impedance Z between the two electrodes 11a and 11a of the cable 10 is connected. The alternating current 13c is incorporated in the configuration. Then, the resistance fluctuation measuring circuit 13 measures and detects the value of the voltage e between the two opposing terminals via the amplifier 13b, and thereby the two electrodes 1
The electrical resistance R of the medium X between 1a and 11a, that is, the electrical impedance Z is measured, and this can be output from the output terminal 13d in the form of an electrical signal S1 to the determination means. Accordingly, the resistance change measuring circuit 13 is connected to the comparison / determination circuit 25 as the determination means, and the comparison / determination circuit 25 compares and determines the material of the medium X based on the electric signal S1. It is possible to determine whether or not the two electrodes 11a, 11a are present in the cast concrete 3 and output a concrete detection signal S2, and also to move the two electrodes 11a, 11a up and down, that is, the cable 10
The two electrodes 11a, 1 in a form that can control the winding operation of the
It is connected to 1a.

The detection control device 15 is, as shown in FIG.
The main control unit 21 is provided, and the main control unit 21 is connected to a storage unit 22, a crown height calculation unit 23, an electrode position detection unit 24, an input / output unit 26, etc. via a bus line. . Input / output unit 2
A computer terminal 27 is connected to the computer 6, and the computer terminal 27 displays the output screen 2 as shown in FIG.
Have nine. Further, a comparison / determination circuit 25 is connected to the main control unit 21 of the detection control device 15. Further, as shown in FIG. 1, a drive circuit 16 connected to the drum 12a of the winch 12 is connected to the detection controller 15, and the winch 12 is provided with an encoder 17. The encoder 17 is adapted to detect the drive amount of the winch 12 by the drive circuit 16 and transmit the detection result to the detection control device 15 in the form of the winch drive signal S3. Position detector 24
Is the two electrodes 11 based on the winch drive signal S3.
The positions of a and 11a can be detected. Therefore, the encoder 17 and the electrode position detection unit 24 detect the positions of the two electrodes 11a and 11a, and output the electrode position signal S4 as a signal indicating the positions so that the position detection in the concrete detector 9 is possible. Constitutes a means. Further, the crown height calculating section 23 is the position detecting means (encoder 17, electrode position detecting section 24) when the concrete detection signal S2 output from the comparison / determination circuit 25 changes.
It is a top end position calculating means for calculating the position of the top end 3a of the concrete 3 that has been placed in the vertical hole 2 from the electrode position signal S4 output from the above.

Since the construction site 1 and the top end position detection device 7 and the like have the above-mentioned structure, when constructing a cast-in-place concrete pile in the vertical hole 2 formed in the construction site 1, , When the vertical hole 2 is excavated and formed, the winch 12
Is driven appropriately to settle the cable 10 in the stabilizing liquid 5, and the lower end, that is, the two electrodes 11a, 11a are positioned at a position having a predetermined height h from the bottom 2a. Then, between the two electrodes 11a, 11a, as the medium X, the stabilizing solution 5
To place. At this time, when a current is applied to the AC bridge 13a of the resistance fluctuation measuring circuit 13 via the AC power supply 13c, the three resistors R1, R2, R3 and the resistance R4 corresponding to the value of the electric resistance R of the stabilizing solution 5 are applied. The voltage e between the two terminals is held at a predetermined value in the form of a potential difference between the two terminals of the bridge. Therefore, the resistance variation measuring circuit 13 can output a value corresponding to the voltage e as the electric signal S1 from the output terminal 13d.

In this state, when the concrete discharge port 6b of the tremie pipe 6 is positioned near the bottom 2a and the concrete 3 is supplied to the concrete supply port 6a, the concrete 3 discharged from the concrete discharge port 6b becomes a vertical hole 2
It is launched from the bottom 2a in the form of being replaced with the stabilizing solution 5. By the way, when the top 3a of the washed-up concrete 3 reaches the height h, the electrodes 11a, 1
The medium X existing between 1a is replaced with concrete 3 from the stabilizing liquid 5. Then, since the stabilizing liquid 5 made of bentonite or the like and the concrete 3 obviously have different values of the electric resistance R, the electric impedance Z between the two electrodes 11a and 11a also changes. As a result, the voltage e generated in the AC bridge 13a changes in the form in which one resistance R4 among the four resistances R forming the AC bridge 13a changes. At this time, the resistance fluctuation measuring circuit 13
The output terminal 13d can output the changed new voltage e in the form of the corresponding electric signal S1 via the amplifier 13b. Therefore, when the value of the voltage e changes at a predetermined time, the two electrodes 11a,
This means that the electric impedance Z between the electrodes 11a has changed, that is, the electric resistance R of the medium X between the two electrodes 11a, 11a has changed. Therefore, as shown in FIG. 2, if the electric signal S1 corresponding to the bridge voltage e is continuously monitored, the change in the output state of the electric signal S1 is detected and determined to detect the two electrodes 11a. , 11a between media X
It is detected that the stable liquid 5 turned into concrete 3.

Therefore, at the time of pouring concrete, the concrete detector 9 is used, and first the computer terminal 27 is used.
For example, the measurement start command P1 is input to the input / output unit 26 of the detection control device 15. Then, the main control unit 21 causes the comparison / determination circuit 25 to read the electric signal S1 output by the resistance variation measurement circuit 13, thereby continuously monitoring the value of the voltage e. Then, the comparison / determination circuit 25 picks up the electric signal S1 output from the resistance variation measurement circuit 13, and stores it in the storage unit in the comparison / determination circuit 25. In this state, when the top end 3a of the cast concrete 3 reaches the two electrodes 11a, 11a, as described above, the impedance Z between the two electrodes 11a, 11a changes, The electric signal S1 corresponding to the value of the voltage e changes.
Therefore, the comparison / determination circuit 25 continuously compares and determines the electric signal S1 and when the electric signal S1 changes, changes the concrete detection signal S2 from the "concrete non-detection state 9" to the "concrete detection state". Output in a changed form. By the output of the signal S2, the two electrodes 11
It is determined and detected that a and 11a are (that is, have entered) in the concrete 3.

When the concrete detection signal S2 is output in this manner, the main control unit 2 of the detection control device 15 which receives the signal is received.
1 transmits a winch drive command P2 to the drive circuit 16. In response to this, the drive circuit 16 winds up the cable 10 and winds up the drum 12a of the winch 12. Then, only the height corresponding to the winding drive amount is 2
The electrodes 11a, 11a are pulled upward.
As a result, the electrodes 11a, 11a, which were previously placed at the position of the top 3a of the concrete 3, are again placed in the stabilizing liquid 5, and as a result, the medium X is transferred from the concrete 3 to the stabilizing liquid 5 again. Return to. Then AC bridge 13
The voltage e generated between the two terminals of a changes again. Therefore,
As described above, the electric signal S1 indicating the value of the voltage e detected by the resistance variation measuring circuit 13 returns to a predetermined value in a form in which the electric resistance R of the stabilizing solution 5 is one of the resistances. Therefore,
Comparison determination circuit 25 that continuously monitors the electrical signal S1
Determines that the electrodes 11a, 11a are again placed in the stabilizing solution 5 and changes the signal S2 from "concrete detection state" to "concrete non-detection state".
In response to this, the main controller 21 receives the winch drive stop command P3.
Is output to the drive circuit 16 to stop the operation of the winch 12.

When the winch 12 is driven, the encoder 17 connected to the winch 12 is
The rotation amount of the drum 12a is detected, and the winch drive signal S3 is output by the amount corresponding to the rotation amount. The main control unit 21 of the detection control device 15 which receives this, the electrode position detection unit 24
Of the two electrodes 11a, 11a in the form of calculating the winding amount of the cable based on the winch drive signal S3.
A relative position (that is, height h) with respect to the bottom 2a is detected, and an electrode position signal S4 is output as a signal representing the position. In this state, when the concrete detection signal S2 changes from the "concrete non-detection state" to the "concrete detection state" as described above, the main control unit 21 causes the crown height calculation unit 23 to detect the concrete detection signal S2. The electrode position signal S4 output from the electrode position detector 24 at the time of change is read. Then, the crown height calculation unit 23
Picks up the electrode position signal S4 at the time when the concrete detection signal S2 changes to the “concrete detection state”, and the two electrodes 11 represented by the electrode position signal S4
The positions of a and 11a are calculated and calculated as the current position of the top end 3a of the concrete 3 cast in the vertical hole 2, and the top end position signal S5 is output. In response to this, the main control section 21 transmits the top end position signal S5 to the storage section 22,
The current position of the top 3a is stored. Therefore, the position information of the crown 3a (that corresponds to the concrete pouring height L1) stored in the storage unit 22 raises the two electrodes 11a, 11a, and this is the concrete 3
It is updated each time it comes into contact with (that is, every time the concrete detection signal S2 is output).

Therefore, the two electrodes 11a, 11a are placed in the stabilizing solution 5, and the concrete 3 is poured into the stabilizing solution 5.
When the top end 3a of the concrete 3 rises and the concrete detection signal S2 changes to the "concrete detection state", the two electrodes 11a, 11a are raised and returned to the stabilizing solution 5 again, By repeating the operation of sequentially detecting the positions of the electrodes 11a, 11a, the positions of the two electrodes 11a, 11a when the concrete detection signal S2 changes to the "concrete detection state" are determined. It is possible to proceed with the concrete placing work while constantly detecting and grasping the position of the top end 3a. At this time, the output screen 2 of the computer terminal 27 connected to the input / output unit 26 of the detection control device 15
At 9, the position of the top end 3a is displayed in real time, as shown in FIG. Therefore, if the input amount of the concrete 3 is input to the computer terminal 27 and is displayed on the output screen 29 together with the position of the top end 3a, the input amount and the setting amount of the poured concrete 3 are set. Height 2
You can grasp the original. As a result, the concrete pouring work can be accurately managed without trouble by adjusting the pulling speed and the position of the tremie pipe 6.

In the above-mentioned embodiment, the concrete detector 9 is used as the top position detecting device 7 and applied to the construction of cast-in-place concrete piles. Alternatively, as shown in FIG. 5, it can be applied to the construction of the underground continuous wall 19 and can be used for monitoring so that concrete does not flow to a place where it should not be. That is, when constructing the underground continuous wall 19, the pit 2 is dug down leaving the ground 39 at each pitch, and the concrete 3 is put in the pit 2 at each pitch.
After pouring, the pits 2 in which the concrete 3 is laid for each pitch 2 and the ground 39 between them are dug to form a new pit 2 '.
And the concrete 3 is connected to the vertical hole 2 ′, and the concrete 3 of the adjacent vertical holes 2 and 2 is connected. Therefore, as shown in FIG. 4, the partition plates 20, 20 are set in the vertical hole 2 to be constructed first in such a manner that the left and right end portions of each rebar 41 are projected to the outside of the partition plate 20. . As a result, the non-casting space 2s in which the concrete 3 is not cast is formed in the vertical hole 2, and the left and right ends of each rebar 41 are arranged in the non-casting space 2s.

In this state, the vertical hole 2 between the partition plates 20, 20
As shown in FIG. 5, when concrete 3 is placed,
The concrete 3 does not adhere to the left and right end portions of the reinforcing bars 41 arranged in the non-casting space 2s, and the reinforcing bars 41 can be bound with the reinforcing bars built in the vertical hole 2'which will be dug later. However, at the time of pouring the concrete, it is troublesome that the concrete 3 leaks to the non-casting space 2s through the partition plate 20. Then, the concrete detector 9 according to the present invention is shown in FIG.
If the electrodes 11a and 11a are set so as to be arranged in the non-casting space 2s as shown in Fig. 3, when the concrete 3 leaks into the non-casting space 2s during the concrete pouring work, this can be detected immediately. You can do it. As a result, it becomes possible to perform a thorough concrete pouring by taking measures such as repairing the leaked portion of the partition plate 20. In addition, in FIG. 5, two electrodes 11a at the tip,
A concrete detector 9 having a cable 10 to which 11a is attached is installed in the space 2s for placing the cable 10 in the vertical hole 2.
It was used by installing it in the form of hanging. However, the two electrodes 11a, 11a of the concrete detector 9 need not necessarily be attached to the tip of the cable 10. For example, in the case of the application example shown in FIGS. 4 to 5, two electrodes 11a, 11a may be attached to the outer wall of the partition plate 20 in a form of being lined up in the vertical direction. Of course, the method of installing the two electrodes 11a, 11a in the concrete placing space is not limited to this, but is arbitrary.

In the above-mentioned embodiment, the concrete placing space in which the two electrodes 11a, 11a are installed is the vertical hole 2. However, the concrete placing space is not necessarily formed in the ground. It does not have to be the pit 2 that was created. Also, in the embodiment, two electrodes 11a, 1
The example in which the detection circuit for detecting the change in the electrical impedance Z between 1a is the resistance fluctuation measurement circuit 13 that measures the voltage e of the AC bridge 13a has been described, but the detection circuit has another configuration. It does not matter if you In addition, in the embodiment, in order to detect the positions of the two electrodes 11a, 11a, the electrode position detection unit 24 is caused to detect based on the winch drive signal S3 indicating the drive amount of the winch 12 detected by the encoder 17. I did it,
Although the example using the position detecting means including the encoder 17 and the electrode position detecting section 24 has been described, the configuration of the position detecting means, that is, the method for detecting the electrode position is not limited to this.

[0020]

As described above, according to the invention of claim 1 of the present invention, the two electrodes 11a, 11a which can be installed in the concrete pouring space such as the vertical hole 2 are provided, and the two electrodes are provided. Electrodes 11a, 11a of the two electrodes 11a,
A detection circuit such as a resistance fluctuation measuring circuit 13 for detecting a change in the electrical impedance Z between the electrodes 11a is connected, and based on an output signal such as an electrical signal S1 output from the detection circuit, the two electrodes 11a, Since the concrete detector 9 is configured by connecting the determination means such as the comparison / determination circuit 25 that determines whether 11a is present in the cast concrete 3 and outputs the concrete detection signal S2, the two When the electrodes 11a, 11a contact the concrete 3, the
Since the electrical impedance Z between the two electrodes 11a, 11a changes and the output signal output from the detection circuit changes, the determination means at this time determines the two electrodes 11a, 11a.
The concrete detection signal S2 can be output by determining that there is concrete in between. Therefore, if two electrodes 11a and 11a are installed at predetermined positions in the concrete placing space when performing the placing work of the concrete 3, the concrete 3 is placed at the place where the two electrodes 11a and 11a are placed. It is possible to easily detect whether or not the has been placed. At this time, whether or not the concrete 3 is present between the two electrodes 11a is electrically determined without depending on the human touch. Thereby, when performing the concrete placing work for constructing the cast-in-place pile or the like, it is possible to save the labor to carry out the placing work while accurately grasping to which position the concrete 3 has been placed. Further, by obtaining the positions of the two electrodes 11a, 11a, the position of the top end 3a of the concrete 3 can be easily detected. Furthermore, when constructing underground continuous walls, concrete 3
If two electrodes are installed in the non-casting space 2s that should not be cast, when the concrete 3 flows into this space, the situation is judged based on the concrete detection signal S2 of the determination means. It can be detected immediately. Therefore, it is possible to detect a concrete pouring defect early and take countermeasures immediately.

According to a second aspect of the present invention, in the concrete detector 9 according to the first aspect, the detection circuit detects an electric resistance R4 between the two electrodes 11a and 11a. It is configured to have one AC bridge 13a and an output terminal 13d for outputting an output signal such as the electric signal S1 to the judging means based on the voltage e between the two terminals of the AC bridge 13a. Therefore, the determining means can determine whether or not the concrete 3 is present based on the change in the voltage e generated between the two terminals of the AC bridge 13a. Then, output terminal 1
When the electric resistance R4 of the medium X arranged between the two electrodes 11a and 11a changes, 3d is an output signal based on the voltage e that accurately reflects the change via the AC bridge 13a. Is output, the determination means can accurately determine whether or not the concrete 3 is present. Therefore, if the concrete detector 9 is used, two electrodes 1
Even if the difference in the electrical impedance Z of the medium X that can be arranged between 1a and 11a is small, it is highly reliable to accurately detect the alteration of the medium X and detect the presence or absence of the concrete 3. It will be possible.

According to the third aspect of the present invention, in the concrete detector 9 according to the first aspect, the two electrodes 11a and 11a are attached to the tip of the cable 10 which can be wound and wound. The above two electrodes 11
An encoder 17 capable of detecting a position of the two electrodes 11a, 11a by providing a driving means such as a winch 12 for moving the a and 11a up and down through the cable 10 and outputting the electrode position signal S4. , Electrode position detector 24
Since the position detecting means such as the above is provided, the driving means moves the two electrodes 11a, 11a up and down, and the judging means judges that there is concrete 3 between the two electrodes 11a, 11a. Then, the position detecting means can detect the positions of the two electrodes 11a, 11a at that time. Therefore, at the time of concrete placing work, the two electrodes 11a, 1
If the concrete detector 9 is set such that 1a hangs down in the concrete pouring space, the two electrodes 11a, 11 which are determined by the determination means to have concrete 3
By detecting the position of a by the position detecting means, the position of the top end 3a of the cast concrete 3 can be easily and accurately obtained.

Further, according to the invention of claim 4 of the present invention, in the concrete detector 9 of claim 3, the position detection is performed when the concrete detection signal S2 output from the determination means changes. A top end position calculating unit such as a top end height calculating unit 23 for calculating the position of the top end 3a of the cast concrete 3 in the concrete placing space from the electrode position signal S4 output from the means is provided. Since the top end position detecting device 7 is configured, the two electrodes 11a, 11a attached to the tip of the cable 10 are moved up and down in the concrete placing space, and the determination means is provided with the two electrodes 11a, 11a. The top end position calculating means can detect the position of the top end 3a of the concrete 3 only by determining whether or not there is the concrete 3 in between. Therefore, at the time of concrete pouring work for constructing cast-in-place piles or the like, it is possible to labor-savingly detect the position of the top end 3a without requiring human power while pouring concrete. Then, because it is possible to perform concrete pouring while always accurately grasping the top position, it is possible to properly adjust the rooting depth of the tremie pipe, the pulling speed, etc. As a result, a good concrete structure can be obtained. It is possible to build.

[Brief description of drawings]

FIG. 1 is a diagram showing a state in which an embodiment of a top position detecting device using a concrete detector according to the present invention is applied to construction of a pile.

FIG. 2 is a diagram showing a concrete detection principle in the concrete detector shown in FIG.

FIG. 3 is a diagram showing an example of a display state of a display unit in the crown position detecting device shown in FIG.

FIG. 4 is a diagram showing a state in which the concrete detector shown in FIG. 1 is applied to construction of an underground continuous wall.

FIG. 5 is a diagram showing a state in which the concrete detector shown in FIG. 1 is applied to the construction of a continuous underground wall.

FIG. 6 is a diagram showing a state where concrete placing work is performed while detecting the top end position of concrete by a conventional method.

[Explanation of symbols]

7 ... Top end position detection device 9 ... Concrete detector 2 ... Concrete placing space (vertical hole) 3 ... Concrete 3a ... Top end 10 ... Cable 11a ... Electrode 12 ... Driving means (winch) 13 ...... Detection circuit (resistance fluctuation measurement circuit) 13a ...... AC bridge 13d ...... Output terminals 17, 24 ...... Position detection means (encoder, electrode position detection section) 23 ...... Top end position calculation means (top end height calculation) Part) 25 ... Judgment means (comparison judgment circuit) S1 ... Output signal (electrical signal) S2 ... Concrete detection signal S4 ... Electrode position signal

Claims (4)

[Claims] 1. A method comprising: two electrodes that can be installed in a concrete pouring space, wherein a detection circuit for detecting a change in electrical impedance between the two electrodes is connected to the two electrodes; Based on the output signal output from the detection circuit, the concrete detection is configured by connecting a determination means for determining whether or not the two electrodes are present in the cast concrete and outputting a concrete detection signal. vessel. 2. The detection circuit has an AC bridge whose electric resistance between the two electrodes is one of the resistances, and outputs the output signal to the judging means based on a voltage between two terminals of the AC bridge. The concrete detector according to claim 1, further comprising an output terminal for outputting. 3. The two electrodes are attached to the ends of a cable that can be reeled out and taken up, and drive means for moving the two electrodes up and down through the cable is provided. The concrete detector according to claim 1, further comprising position detecting means capable of detecting the position of the electrode and outputting it as an electrode position signal. 4. The concrete detector according to claim 3, wherein in the concrete placing space, from the electrode position signal output from the position detecting unit when the concrete detection signal output from the determining unit changes. The top end position detecting device configured by providing a top end position calculating means for calculating the top end position of the cast concrete in.