Method and apparatus for confirming finished state of underground wall

Abstract

To confirm the finished amount of an underground wall in a short time without pulling up an excavator, and to grasp not only the distance to the underground wall but also the strength of the underground wall.SOLUTION: When a transmitter and a receiver (sensor 40) of ultrasonic waves are inserted into an underground hole 10 filled with muddy water and a distance to an underground wall (12) is measured by the ultrasonic waves to confirm a finished shape of the underground wall (12), the transmitter and the receiver (sensor 40) of the ultrasonic waves are arranged on a side surface (frame 26) of an excavator 20 for excavating the underground hole 10. A pseudo random wave of a frequency selected according to the concentration of the muddy water is transmitted from the transmitter toward the underground wall (12), and a distance to the underground wall (12) and an intensity of the underground wall (12) are calculated from a propagation time and a reception amplitude of a reception wave (measurement signal 60) received by the receiver, propagated through the muddy water, and reflected and returned by the underground wall (12).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method and device for checking the completed form of an underground wall, and in particular to a method and device for checking the completed form of an underground diaphragm wall that is constructed underground with reinforced concrete for the purpose of waterproofing or reinforcing a structure. [Background technology]

[0002] For the purpose of watertightness and structural reinforcement, a diaphragm wall (also called a diaphragm wall) is known, in which a rectangular parallelepiped trench measuring, for example, 5 m wide x 10 m long x 70 m deep is dug underground and reinforced concrete is constructed inside it. In recent years, many such diaphragm walls have been constructed for purposes such as watertight walls at nuclear power plants and reinforcing deep station buildings for the Linear Shinkansen.

[0003] Specialized excavators are used for construction, but quality control of the excavated wall surface is important; if the side walls are not excavated sufficiently, the wall thickness will be insufficient, affecting its strength and water-stopping ability. Conversely, if the side walls are excavated too deeply, they may interfere with adjacent piles and other underground structures, and in some cases may even be damaged. Furthermore, if the wall surface is damaged, it will peel off and excavation mud will accumulate at the bottom of the diaphragm wall, reducing the quality of this area, so it is important to check the condition of the wall surface, especially its strength.

[0004] One example of a measurement technique for measuring the condition of underground hole walls is the technique described in Patent Document 1. As shown in Fig. 1(A), this technique involves drilling an underground hole 10 using an excavator 20 equipped with a bottom frame 22 and side frames 26, with, for example, a pair of drum cutters 24 mounted on the bottom frame 22, and then lifting the excavator 20 using wires 16 to fill the hole with muddy water, as shown in Fig. 1(B). Then, as shown in Fig. 1(C), a measuring device 30 equipped with a measuring sensor 32 that transmits and receives ultrasonic waves is suspended within the underground hole 10 using wires 36, and ultrasonic waves are transmitted and received by the measuring sensor 32 toward the underground hole wall (also simply referred to as the hole wall) 12, and the round-trip propagation time of the reflected waves is measured to calculate the distance to the hole wall 12. Since the speed of sound in muddy water changes depending on the concentration of the muddy water, the measuring device 30 is equipped with a pair of calibration sensors 34 in addition to the measurement sensor 32 to measure the speed of the direct wave, and the change in speed of sound due to the concentration of the muddy water is corrected by calculating the distance to the hole wall 12 = round-trip propagation time ÷ calibrated speed ÷ 2.

[0005] After the measurement is completed, the measuring device 30 is pulled up from the underground hole 10 by the wire 36, and as shown in FIG. 1(D), the excavator 20 is inserted into the underground hole 10 by the wire 16 again to perform excavation.

[0006] Patent document 2 also describes a method in which an ultrasonic transmitter / receiver is moved up and down in a hole filled with muddy water while transmitting and receiving ultrasonic pulses, and the amplitude of the reflected waves is automatically adjusted, increasing the gain when the muddy water concentration is high and decreasing the gain when the muddy water concentration is low, and recording the results on recording paper. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6618541 [Patent Document 2] Patent No. 3668690 Summary of the Invention [Problem to be solved by the invention]

[0008] However, as shown in FIG. 1, conventional methods require the removal of the excavator 20 to insert the measuring device 30 into the underground borehole 10. Furthermore, since highly concentrated mud cannot be used, the mud must be replaced with diluted mud or water. Therefore, the measurement work, including the removal of the excavator 20, the replacement of the mud, and the reinstallation of the excavator 20, takes half a day to a full day. Furthermore, due to this time constraint, measurements can usually only be taken at the end of the work day, making it difficult to timely identify insufficient / excessive excavation or the occurrence of borehole wall collapse. Furthermore, the lifting device for the measuring device 30 must be separate from the lifting device for the excavator 20. Furthermore, the technologies described in Patent Documents 1 and 2 cannot measure the amplitude of reflected waves, making it impossible to confirm the condition of the borehole wall 12, which is necessary to determine whether the borehole wall has collapsed. Furthermore, when an independent calibration sensor 34 is attached to the excavator 20, there is a high possibility of it being damaged during lifting.

[0009] The present invention has been made to solve the above-mentioned conventional problems, and aims to enable confirmation of the progress of underground wall construction in a short time without lifting up the excavator, and to enable not only the distance to the underground wall but also the strength of the underground wall to be grasped. [Means for solving the problem]

[0010] The present invention solves the above-mentioned problems by providing a method for checking the completed shape of a diaphragm wall, which comprises inserting an ultrasonic transmitter and receiver into a diaphragm hole filled with muddy water, measuring the distance to the diaphragm wall with ultrasonic waves, and checking the completed shape of the diaphragm wall. The method comprises arranging the ultrasonic transmitter and receiver on the side of an excavator used to excavate the diaphragm hole, transmitting pseudo-random waves of a frequency selected according to the concentration of the muddy water toward the diaphragm wall from the transmitter, and calculating the distance to the diaphragm wall and the strength of the diaphragm wall from the propagation time and received amplitude of the received waves received by the receiver, which propagate through the muddy water and are reflected by the diaphragm wall and return.

[0011] Here, the same sensor can be used as both the transmitter and the receiver by switching between them.

[0012] Furthermore, a plurality of the transmitters and receivers can be disposed on one side of the excavator.

[0013] Furthermore, by using multiple ultrasonic transmitters and receivers arranged on one side, it is possible to switch between measuring any reflected waves reflected by the underground wall and direct waves that propagate directly between the transmitter and receiver.

[0014] Furthermore, the measurement signal obtained by the arbitrary reflected wave can be calibrated using the calibration signal obtained by the direct wave.

[0015] Also, the transmitters and receivers can be disposed on all sides of the excavator.

[0016] Also, the frequency can be set low when the muddy water is thick, and high when the muddy water is thin.

[0017] The present invention also solves the above-mentioned problems by providing an apparatus for checking the completion of a diaphragm wall, which comprises an ultrasonic transmitter and receiver inserted into a diaphragm filled with muddy water, and which measures the distance to the diaphragm wall using ultrasonic waves to check the completion of the diaphragm wall, the apparatus comprising: a transmitter arranged on the side of a boring machine for excavating the diaphragm wall, which transmits pseudo-random waves of a frequency selected according to the concentration of the muddy water toward the diaphragm wall; a receiver arranged on the side of the boring machine for excavating the diaphragm wall, which receives the received waves that propagate through the muddy water and are reflected by the diaphragm wall, and means for calculating the distance to the diaphragm wall and the strength of the diaphragm wall from the propagation time and received amplitude of the received waves.

[0018] Here, the same sensor can be used as the transmitter and the receiver interchangeably.

[0019] Furthermore, a plurality of the transmitters and receivers can be disposed on one side of the excavator.

[0020] In addition, a means can be provided for switching between measuring any reflected waves reflected by the underground wall and direct waves that propagate directly between the transmitter and receiver using multiple ultrasonic transmitters and receivers arranged on one side.

[0021] The apparatus may also include means for calibrating the measurement signal obtained by the arbitrary reflected wave using the calibration signal obtained by the direct wave.

[0022] Also, the transmitters and receivers can be disposed on all sides of the excavator.

[0023] Also, a means for lowering the frequency when the muddy water is thick and for raising the frequency when the muddy water is thin can be provided. [Effects of the Invention]

[0024] According to the present invention, there is no need to remove the excavator, replace the mud, install a measuring instrument, or reinstall the excavator, so measurements can be made quickly and without waiting. Furthermore, since a pseudorandom wave is used as the emitted wave, the frequency of which can be controlled and the amplitude of the reflected wave can be measured, the influence of attenuation can be reduced by changing the frequency according to the muddy water concentration. Furthermore, by measuring the amplitude, not only the distance to the underground wall but also the strength of the underground wall can be determined. [Brief explanation of the drawings]

[0025] [Figure 1] Cross-sectional view for explaining the prior art [Figure 2] 1 is a cross-sectional view showing a first embodiment of the present invention; [Figure 3] Also floor plan [Figure 4] Schematic diagram showing the sensor configuration [Figure 5] FIG. 10 is a plan view showing the sensor attached to the frame. [Figure 6] A diagram showing the sensor switching circuit [Figure 7] A diagram showing an example of the sensor's transmission / reception status. [Figure 8] The same figure shows the results of measurements taken with different concentrations of muddy water. [Figure 9] 1 is a cross-sectional view showing a second embodiment of the present invention; [Figure 10] Also floor plan DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the contents described in the following embodiments. Furthermore, the components in the embodiments described below include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the embodiments described below may be combined as appropriate, or may be selected and used as appropriate.

[0027] In the first embodiment of the present invention, as shown in Figure 2 (cross-sectional view) and Figure 3 (plan view), a total of four sensors 40 that can function as transmitters and receivers are provided on each side, at the top, bottom, left, and right corners of both sides of the side frame 26 of the excavator 20. Since the measurement object in this embodiment is an underground diaphragm wall, it is not necessary to measure the side surfaces in the left and right directions in Figures 2 and 3.

[0028] 4 can be used as the sensor 40. By using, for example, a cylindrical piezoelectric element as the piezoelectric element 42, it is possible to obtain a small size and a large output. Note that the shape of the piezoelectric element 42 is not limited to a cylindrical shape, and it may be, for example, a columnar or disk shape.

[0029] In the figure, reference numeral 44 denotes a resin for fixing the piezoelectric element 42, and 46 denotes a holder made of, for example, hard plastic, for covering the piezoelectric element 42.

[0030] A holder 46 including the piezoelectric element 42 can be attached to the side frame 26 of the excavator 20 as shown in FIG.

[0031] The sensor 40 is provided with a movable, semi-cylindrical cover 48 made of, for example, steel, and by turning the cover 48 half a turn to close it during excavation, the sensor 40 can be prevented from being damaged.

[0032] As shown in FIG. 6, by switching the connection of the sensor 40 between a transmitting circuit 52 and a receiving circuit 54 using a changeover switch 50, it is possible to measure reflected waves and direct waves at any location with a small number of sensors, as shown in FIG. 7.

[0033] The transmitted wave is a pseudo-random wave. When the muddy water concentration is high, the frequency is lowered to about 10 kHz, and when the muddy water concentration is low, the frequency is raised to about 40 kHz, making it less susceptible to attenuation by the muddy water.

[0034] As shown in Figure 3, the distance from the borehole wall 12 and the strength of the borehole wall 12 can be measured by a measurement signal 60 transmitted toward the wall, and calibration can be performed by a calibration signal 62 that propagates directly between the sensors 40.

[0035] The distance to the borehole wall 12 can be calculated from the propagation time, and the strength of the borehole wall 12 can be calculated from the received amplitude. In this case, an appropriate frequency can be selected depending on the concentration of the muddy water, for example, a low frequency when the concentration of the muddy water is high, and a high frequency when the concentration of the muddy water is low.

[0036] Since the measurement signal 60 emitted toward the wall is calibrated using the calibration signal 62 that propagates directly between the sensors 40, there is no need to provide a separate calibration sensor, and it will not be damaged.

[0037] Because pseudorandom waves are used, investigations can be carried out even with highly concentrated muddy water, and there is no need to replace it with water. Furthermore, because there is no need to raise the excavator 20, there is no waiting time, the current process can be halved, and investigations can be carried out whenever necessary.

[0038] In this embodiment, the sensors 40 are attached to the top, bottom, left and right of the excavator 20, so that measurements can be taken at multiple locations at once.

[0039] The results of measurements taken in the above embodiment with varying muddy water concentrations are shown in Figure 8. It can be seen that the wall strength and amplitude are proportional, and that the higher the muddy water concentration, the lower the amplitude.

[0040] Next, a second embodiment of the present invention in which sensors 40 are arranged on all sides of the excavator 20 is shown in FIG. 9 (cross-sectional view) and FIG. 10 (plan view).

[0041] According to this embodiment, measurements can be made over the entire circumference of the excavator 20.

[0042] In the above-described embodiments, the sensor 40 is used as both a transmitter and a receiver, and is therefore simple in construction. However, it is also possible to provide a dedicated transmitter and receiver.

[0043] Furthermore, the sensor is not limited to one that uses a piezoelectric element.

[0044] In the above embodiment, the present invention is used to check the progress of underground diaphragm walls, but the application of the present invention is not limited to this, and it can also be applied to check the progress of underground walls other than diaphragm walls. [Explanation of symbols]

[0045] 10…Underground hole 12…Underground hole wall 16...Wire 20...Excavator 22...Bottom frame 24...Drum cutter 26...Side frame 40...Sensor 42...Piezoelectric element 50...Selector switch 52...Transmitting circuit 54...Receiver circuit 60...Measurement signal 62...Calibration signal

Claims

1. When inserting an ultrasonic transmitter and receiver into an underground hole filled with muddy water, measuring the distance to the underground wall with ultrasonic waves, and checking the completed shape of the underground wall, an ultrasonic transmitter and a receiver are disposed on a side of a drilling machine for drilling an underground hole; The transmitter transmits pseudo-random waves of a frequency selected according to the concentration of the muddy water toward the underground wall, This method for checking the completed form of an underground wall is characterized in that the distance to the underground wall and the strength of the underground wall are calculated from the propagation time and reception amplitude of the received wave received by the receiver, propagated through the muddy water, reflected by the underground wall and returned.

2. 2. The method for checking the completed shape of an underground wall according to claim 1, wherein the same sensor is used as both the transmitter and the receiver by switching between the two.

3. 2. The method for checking the finished shape of an underground wall according to claim 1, wherein a plurality of the transmitters and the receivers are arranged on one side of the excavator.

4. A method for checking the finished shape of an underground wall as described in claim 3, characterized in that a plurality of ultrasonic transmitters and receivers are arranged on one side, and measurements are made by switching between any reflected waves reflected by the underground wall and direct waves that propagate directly between the transmitter and receiver.

5. 5. The method for checking the finished shape of an underground wall according to claim 4, wherein the measurement signal obtained by the arbitrary reflected wave is calibrated using the calibration signal obtained by the direct wave.

6. 2. The method for checking the finished shape of an underground wall according to claim 1, wherein the transmitters and the receivers are disposed on all sides of the excavator.

7. 2. The method for checking the finished shape of an underground wall according to claim 1, wherein the frequency is set low when the concentration of the muddy water is high and set high when the concentration of the muddy water is low.

8. An underground wall completion confirmation device for confirming the completion of an underground wall by inserting an ultrasonic transmitter and receiver into an underground hole filled with muddy water and measuring the distance to the underground wall with ultrasonic waves, a transmitter disposed on a side of a drilling machine for drilling an underground hole, which transmits pseudo-random waves of a frequency selected according to the concentration of mud toward an underground wall; a receiver disposed on a side of a drilling machine for drilling an underground hole, for receiving a received wave that propagates through the mud water and is reflected by an underground wall and then returned; a means for calculating the distance to the underground wall and the strength of the underground wall from the propagation time and the received amplitude of the received wave; An underground wall completion confirmation device comprising:

9. 9. The underground wall completion confirmation device according to claim 8, wherein the same sensor is used as both the transmitter and the receiver, and is switchable.

10. 9. The underground wall completion confirmation device according to claim 8, wherein a plurality of the transmitters and the receivers are arranged on one side of the excavator.

11. The underground wall completion confirmation device described in claim 10, characterized in that it is equipped with a means for switching between measuring any reflected wave reflected by the underground wall and a direct wave that propagates directly between the transmitter and receiver using multiple ultrasonic transmitters and receivers arranged on one side.

12. The underground wall completion confirmation device according to claim 11, characterized in that it is provided with a means for calibrating the measurement signal obtained by the arbitrary reflected wave using the calibration signal obtained by the direct wave.

13. 9. The underground wall completion checking device according to claim 8, wherein the transmitters and the receivers are arranged on all sides of the excavator.

14. 9. The apparatus for checking the finished shape of underground walls according to claim 8, further comprising means for lowering the frequency when the concentration of the muddy water is high and for raising the frequency when the concentration of the muddy water is low.

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