JP3405207B2 - Judgment method of ground supported by excavator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining a supporting ground by an excavator, and more particularly, it obtains vibration data of an excavator, analyzes its frequency, and determines the position of the supporting ground based on this frequency analysis. The present invention relates to a determination method.

[0002]

2. Description of the Related Art Among the construction works, it is necessary to grasp the position of the supporting ground in the ground in order to secure the bearing capacity and water impermeability of foundation piles and impermeable walls constructed in the ground. As a method of grasping such supporting ground, a boring survey is carried out in advance at a predetermined position within the construction range, and an assumed geological map within the construction range is created based on the soil column diagram created from this survey result. , The change of the stratum and the location of the foundation were decided.

However, in such a method of grasping the supporting ground, since the range of the boring survey is limited, a problem occurs when the depth of the supporting ground is rapidly changed.

Therefore, for example, when excavation work is carried out with an auger type excavator, the magnitude of vibration in the frequency range of 5 to 10 Hz is measured, and the change in the magnitude of this vibration is prepared in advance. A method for grasping the position of the supporting ground by comparing it with the existing soil column diagram is disclosed in Japanese Patent Publication No. 2-43846.

However, the method of grasping or confirming the supporting ground disclosed in this publication has the technical problems described below.

[0006]

That is, in the method of confirming the supporting ground disclosed in the above-mentioned official gazette, it is 5 to 10
The magnitude of the vibration within the frequency range of Hz is measured, and the position of the supporting ground is grasped by comparing the change in the magnitude of the vibration with the soil column diagram prepared in advance.

However, for example, when gravel or the like exists in the ground, and when excavating such a place, the magnitude of vibration becomes very large, and it is mistakenly recognized as a supporting ground. It is difficult to find the position.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a support ground of an excavator capable of more accurately confirming the position of the support ground. It is to provide a determination method.

[0009]

To achieve the above object, the present invention converts the vibration data corresponding to the excavation depth of a vibration sensor attached to an excavator into frequency spectrum data to determine the position of the supporting ground. In the method, the average value of the maximum value for each frequency band of the frequency spectrum data is obtained, and the position of the supporting ground is obtained from the change of the average value, wherein the average value is for each frequency band.
After finding multiple maximum values of
Remove the old maximum and order the average of multiple front and rear measurements.
The moving average value is calculated next . According to the supporting ground determination method configured in this way, the average value of the maximum values for each frequency band of the frequency spectrum data is calculated, and the position of the supporting ground is calculated from the change in this average value. As in the case where the support ground is measured by measuring, the influence of a peculiar measurement value such as when encountering a large gravel is reduced, and a more accurate judgment can be performed. In this case, the average value is
After obtaining multiple maximum values for each wave number band, set a new maximum value.
Remove the old maximum value each time you want to
Since the average value is used as the moving average value,
Excavation and judgment and confirmation of supporting ground in real time
You can The vibration sensor may be any one of an acceleration sensor attached to a rod of the excavator, an acceleration sensor attached to a reader supporting the rod, and an acoustic sensor installed on the ground surface near the excavator. You can choose. In the case of this configuration, the configuration of the device is simplified by selecting an acceleration sensor attached to a leader supporting the rod or an acoustic sensor installed on the ground surface in the vicinity of the excavator. The frequency band may be set to a low frequency band equal to or lower than the natural frequency of the rod and equal to or lower than 200 Hz. By setting such frequency band, it is possible to eliminate the influence of the natural frequency of the excavator and determine the support ground in multiple frequency bands, so it is possible to more reliably confirm the position of the support ground. it can.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. 1 to 3 show an embodiment of a method for determining a supporting ground by an excavator according to the present invention.

The excavator 10 shown in FIG. 1 is used for a so-called soil cement continuous wall construction method (SMW construction method) and has an auger rod 12. The auger rod 12 has a drill bit at the tip,
On the outer peripheral surface, auger screws 14 are intermittently projected at intervals in the vertical direction.

A plurality of auger rods 12 are arranged in series in a direction perpendicular to the plane of the drawing of FIG. 1, and between adjacent auger rods 12, the auger screw 14 has a uniform radius of rotation when seen in a plan view. It is arranged so as to overlap.

A supply passage for a hardening material (cement milk or the like) is formed along the axial direction of each auger rod 12, and an injection port for the hardening material is formed on the side surface (not shown). ).

The upper end side of the auger rod 12 is supported by the rotary drive unit 16. Rotation drive unit 16
Is vertically movably supported by the reader 18, and the rotation drive unit 16 is vertically moved along the reader 18 by an up / down moving device (not shown).

The leader 18 is a crawler type traveling vehicle 20.
Is supported at one end thereof via a telescopic jack 22 in a vertically extending state.

A depth sensor 24 for detecting the penetration depth at the tip position of the auger rod 12 is provided on the upper side of the rotary drive unit 16.
Are arranged. The depth sensor 24 is, for example, of a rotary encoder type, and its installation location is not limited to the illustrated location.

A vibration sensor 26 is installed on the upper end side of the auger rod 12. This vibration sensor 26
Is composed of an acceleration sensor capable of measuring vibration in three-dimensional directions (vertical, horizontal, circumferential), and is fitted and fixed in a recess provided on the side surface of the auger rod 12, as shown in FIG.

The location where the vibration sensor 26 is installed is
Not limited to the upper end side of the auger rod 12, for example,
It can also be installed on the bottom of the reader 18, as shown in FIG.

Further, the acoustic sensor 2 having high sensitivity in the low frequency region
8. For example, when a microphone is used, it may be installed near the excavation hole of the auger rod 12, as shown in FIG.

In this case, an acceleration sensor is attached to the bottom of the leader 18 that supports the rod 12, or the excavator 1
If the acoustic sensor 28 is installed on the surface of the ground near 0, the radio equipment required when the vibration sensor 26 is provided at the upper end of the auger rod 12 is not required, and there is an advantage that the structure of the device is simplified.

A transmitter 30 is connected to the vibration sensor 26 installed on the auger rod 12. On the other hand, a wireless repeater 32 that receives a detection signal of the vibration sensor 26 and amplifies and outputs the received detection signal is installed on the traveling vehicle 20 side. Further, an arithmetic controller 34 is installed at a place away from the traveling vehicle 20.

The wireless repeater 32 has a receiving antenna 32a and a transmitting antenna 3 as shown in the block diagram of FIG.
2b and an amplifier circuit and the like built in the device main body 32c are provided so as to more reliably transmit the signal detected by the vibration sensor 26 to a long distance. If it can be directly transmitted to 34, it is not always necessary.

The arithmetic and control unit 34 has a so-called microcomputer as a main component, and is provided with a receiving antenna 34a and an apparatus main body 34b. Device body 3
The receiving portion 3 connected to the receiving antenna 34a is provided in 4b.
4c and the A / D converter 34d connected to the receiver 34c
A CPU 34e, a memory 34f, and a display 34g are provided.

The receiving section 34c receives the vibration signal detected by the vibration sensor 26 and transmitted from the wireless repeater 32 via the receiving antenna 34a. A / D converter 34d
Converts the vibration signal received by the receiving unit 34c and the depth signal sent from the depth sensor 24 into a digital signal and sends the digital signal to the CPU 34e.

The CPU 34e determines the supported ground position in the ground based on the vibration signal and the depth signal sent from the A / D converter 34d according to the procedure stored in the memory 34f in advance. The display 34g is the CPU 34
The result determined by e is displayed.

FIG. 4 shows an example of an execution procedure when the CPU 34e determines the support ground. When the procedure shown in the figure starts, first, in step s1, initialization is performed.

For the initial setting, a geological column diagram is created by a boring survey conducted in advance, and the geological depths H _{1 to} H _n corresponding to the layers _{1 to n} are set from the geological column diagram, or The sampling period for vibration measurement by the vibration sensor 26 is input.

FIG. 5 shows the ground conditions input, that is, the relationship between the formations _{1 to} n and the formation depths H _{1 to} H _n .

When the initial setting is completed, the rotation driving unit 16 rotates the auger rod 12 to penetrate into the ground, and while continuing this operation, the vibration and depth sensor 2
The measured values of 6, 24 are fetched and stored in the memory 34g (step s2).

In the following step s4, it is judged whether or not the measured value of the depth sensor 24 has reached the set formation depths H _{1 to} H _n , and if it is judged that the depth has not been reached, the step is carried out. Returning to s1, the same processing is continued.

The geological depth H ₁ set in step s4
_If it is determined that Hn has been reached, step s5 is executed. In step s5, the set formation depth H ₁ to H _n
The measurement values of the vibration sensor 26 obtained inside are averaged, and n time-series data obtained by the averaging process are stored in the memory 34f as vibration data f (t1) to f (tn). To be done.

The averaging process performed here is, for example, a process of subtracting dark vibration data previously measured in the idling state of the auger rod 12 from each measurement value, or a process which is apparently erroneous data. Such as removing.

The vibration data f (t1) to f (tn)
Is determined from the set sampling period, the formation depths H _{1 to} H _n of the formations _{1 to n,} and the penetration speed of the auger rod 12.

The vibration data f (t obtained in this way
Waveform diagrams of 1) to f (tn) are shown in FIG. In each of the obtained vibration data f (t1) to f (tn), the horizontal axis represents time and the vertical axis represents the magnitude of vibration.

In the subsequent step s5, a process of Fourier transforming each of the n pieces of vibration data f (t1) to f (tn) is performed, and n pieces of frequency spectrum data F1 (w) to Fn obtained by the Fourier transform. (W) is stored in the memory 34f, and the process proceeds to step s7.

FIG. 7 shows a waveform diagram of the frequency spectrum data F1 (w) to Fn (w) after the Fourier transform. Obtained frequency spectrum data F1 (w) to F
In n (w), the horizontal axis represents frequency and the vertical axis corresponds to the magnitude of vibration.

At step s7, a plurality of frequency bands b1 to b1 of the frequency spectrum data F1 (w) to Fn (w).
The maximum value F _{max for} each bn is calculated, and each frequency band b1
The average value F _maxav of the maximum values F _max is calculated and stored for each bn.

In this case, a plurality of frequency bands b1 to bn
Is, for example, 2 to 5 Hz, 5 to 20 Hz, 20 to 40 H
z is set to a low frequency lower than the natural frequency of the auger rod 12.

At the subsequent step s8, the average value F of the maximum values F _max for each frequency band is set between the set formation depths H _{1 to} H _n.
It is determined whether _maxav has changed significantly. If it has not changed significantly, the process returns to step s2 to continue the measurement.

On the other hand, if it is determined in step s8 that the average value F _maxav has changed significantly, it is determined that there is a supporting ground layer in the vicinity of the changed ground layer, and the procedure ends.

FIG. 8 shows the measurement results when the method for determining the supporting ground, which is carried out by the above procedure, is applied to the actual work. In this execution work, in the geological columnar diagram shown in FIG. 9 created by the boring survey performed in advance, the supporting ground is determined from the bottom for Chinen sandstone, sandy limestone, lime algae limestone, and foraminiferal limestone, Measurements were made at each of the three drill holes.

The vibration sensor 26 was installed at the bottom of the reader 18, and the vibration sensor 26 was directly connected to the A / D converter 34D without using a wireless system. The graph shown in Fig. 8 shows the frequency band (2-5Hz, 5-20H) in each layer.
z, 20 to 40 Hz) average value F _maxav of maximum values F _max
Is.

From the measurement results shown in the figure, the maximum value F _max
The mean value F _maxav of F _varies significantly between sandy limestone and Chinen sandstone in any frequency band, and the frequency band in each layer (2 to 5 Hz, 5 to 20 Hz, 20 to 4)
It is understood that the support ground can be determined by _obtaining the average value F _maxav change of the maximum value F _max for each 0 Hz). The Chinen sandstone is known as a hard ground by those skilled in the art.

By the way, according to the supporting ground judging method performed as described above, the frequency spectrum data F1 (w)
~ Fn (w) average value F of maximum values F _max for each frequency band
_{Since maxav} is _calculated and the position of the supporting ground is _{calculated from} the change in this average value F _maxav , it is peculiar to the case where a large gravel is encountered, such as when simply measuring the magnitude of vibration to confirm the supporting ground. Accurate judgment can be made because the influence of various measurement values is very small.

FIG. 10 is a graph of the measurement results when another determination method is performed at the same working point as in the case described above. In this determination method, step s7 for _obtaining the average value F _maxav in the procedure shown in FIG. 4 is changed as follows.

That is, in the above-mentioned procedure, the maximum value F _{max of} each frequency band of the frequency spectrum data F1 (w) to Fn (w) is calculated, and then the average value F _{maxav is} obtained. Maximum value F _{max for} each frequency band
After a plurality of values are obtained, an average value of a plurality of front and rear maximum values F _max is sequentially set as a moving average value, and the moving average values are compared, and a portion having a large change is determined to be a support ground.

More specifically, referring now to FIG.
In the frequency band b1, three maximum values F _max 1-3
When the maximum value F _max 4 is calculated, the oldest maximum value F _max 1 is removed and the average of the remaining maximum values F _max 2 to 4 is calculated. The value is obtained, and thereafter, each time a new maximum value is obtained, the old data is removed and new data is added to obtain an average value.

Then, by sequentially comparing the average values thus obtained, it is determined that a portion having a large change is the support ground. In FIG. 10, the moving average value greatly changes between sandy limestone and Chinen sandstone in any frequency band, as in FIG. 8, and it can be seen that the support ground can be determined.

In this way, the maximum value F for each frequency band
_{After obtaining} a plurality of _max values, the old maximum value is removed each time a new maximum value is obtained, the average value of a plurality of front and rear maximum values F _max is sequentially obtained, and the moving average value is obtained. If the support ground is reversed, the support ground can be determined and confirmed in real time as the excavator 10 excavates.

The maximum value F _{max for obtaining} this moving average
Is not limited to 3, and any number may be used as long as it is plural.

[0051]

As described above in detail in the embodiments,
According to the method for determining the supporting ground by the excavator according to the present invention, the position of the supporting ground can be confirmed more accurately than the conventional determination method.

[Brief description of drawings]

FIG. 1 is an overall view of an excavator to which a supporting ground determination method according to the present invention is applied.

2 is a front view and a side view of a vibration sensor attached to the excavator of FIG. 1. FIG.

FIG. 3 is a block diagram of a control system used in the method for determining a supporting ground according to the present invention.

FIG. 4 is a flowchart showing an example of a processing procedure of the arithmetic controller shown in FIG.

FIG. 5 is an explanatory diagram showing an example of a ground condition to be determined by the present invention.

FIG. 6 is a waveform chart of vibration data used in the determination method of the present invention.

FIG. 7 is a waveform diagram after Fourier transform of vibration data used in the determination method of the present invention.

FIG. 8 is a graph of measurement results when the determination method of the present invention is applied to a working process.

FIG. 9 is a geological column diagram of the same construction work.

FIG. 10 is a graph of a measurement result when another example of the determination method of the present invention is applied to a working process.

[Explanation of symbols]

10 excavator 12 Auger rod 14 Auger screw 16 rotary drive 18 leader 24 depth sensor 26 Vibration sensor 34 Arithmetic controller

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-158244 (JP, A) JP-A-62-291392 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01V 9/00 E02D 1/02 G01B 17/00

Claims (3)

(57) [Claims] 1. A method for determining the position of a supporting ground by converting vibration data corresponding to an excavation depth of a vibration sensor attached to an excavator to determine the position of a supporting ground, the maximum value of each frequency band of the frequency spectrum data A method of obtaining an average value and obtaining the position of the supporting ground from the change of the average value , wherein the average value is a plurality of maximum values for each frequency band.
Later, each time a new maximum value is obtained, the old maximum value is removed.
The moving average value that sequentially obtains the average value of multiple front and rear measurement values.
The method for determining the support ground by an excavator is characterized by: 2. The vibration sensor is a rod of the excavator.
Acceleration sensor mounted on the
Accelerometer mounted on the feeder, near the excavator
Select from one of the acoustic sensors installed on the ground surface
The excavator according to claim 1, characterized in that
Judgment method of supporting ground. 3. The frequency band is the natural circumference of the rod.
Multiple in the low frequency band below 200Hz, which is less than the wave number
The excavator according to claim 2, wherein the setting is performed.
Judgment method of supporting ground.