JPH02248837A - Soil discriminator - Google Patents

Abstract

PURPOSE:To achieve a higher accuracy by controlling an amplification factor of an output signal of a vibration sensor based on a penetration resistance value. CONSTITUTION:A processing rod 1 is penetrated into earth with a penetrator 7 to catch a vibration and a penetration resistance near the tip of the rod 1 with an acceleration sensor 2 and a load sensor 3. An arithmetic processor 11 discriminates a particle size of earth according to a relationship between a waveform characteristic value of an output signal of the sensor 2 and the penetration resistance based on an output signal of the sensor 3. Based on the penetration resistance value, an amplification factor of an amplifier 8 for the sensor 2 is controlled variably to turn a vibration output signal to be amplified with the amplifier 8 to a signal level optimum to a waveform signal processing. A particle size is judged according to a relationship between a mean of effective values of vibration output signals at the optimum signal level and the penetration resistance obtained from the load sensor. Thus, for example, an amplification factor of a vibration output in clay is made larger than that in gravel thereby enabling accurate detection of vibration information intrinsic to clay without being buried in noises.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a soil quality determination device that can determine soil quality, particularly soil particle size, etc. in real time. Jl! can detect soil changes in the ground in real time and provide feedback to the construction system! This invention relates to a soil quality determination device that can also be used as a listing monitoring device.

[Prior Art] Devices aimed at real-time soil investigation at the current location include +** penetration testing machines, Dutch-style or Swedish-style penetration testing machines, etc.

Since both testing machines measure the resistance of the soil when an exploration rod is penetrated into the soil or rotated in the soil, only the strength of the soil can be determined.

However, in stabilizing soft ground, controlling the injection of mud material according to the soil quality in shield construction methods, etc., problems often arise not only with the strength of the soil but also with the particle size of the soil.

On the other hand, conventional soil particle size determination methods generally involve taking a soil sample during a penetration test, and then testing and evaluating the sampled sample indoors. However, according to this method.

■Disturbing the sample during sampling (for example, when collecting samples from thin strata, soil from other strata gets mixed in); ■It takes time and effort from sampling to testing and evaluation.

There is a drawback.

For this reason, recently, among the phenomena that occur when rods penetrate,
In addition to measuring soil resistance, we also measured other phenomena.

A method is being adopted that determines soil properties, including soil strength and particle size, in real time at the current location.

FIG. 11 is a diagram showing the penetration part of one of the devices, a soil type determination device using vibration acceleration. In the same figure, 50
is an exploration rod, which includes a pipe-shaped main body 51 and a conical cone 52 disposed at the tip of the main body 51. 53 is an acceleration sensor disposed inside the cone 52; 54 is a load sensor (load cell) equipped with a strain gauge; one end of the load sensor 54 is located at the rear end of the cone 52;
The other ends are disposed in close contact with the step portions 51a of the main body portion 51, respectively. The penetrating portion thus formed is penetrated into the soil at a constant speed by a penetrating device 55 such as a hydraulic cylinder connected to the rear end of the exploration rod 50. At this time, if the penetration resistance applied to the cone 52 is detected by the load sensor 54, the strength of the soil can be evaluated in the same manner as in the conventional penetration test method. Furthermore, when the exploration rod 50 penetrates into the soil, vibrations (vibration acceleration, sound, etc.) that vary depending on the particle size of the soil are caused by friction between the cone 52 and the soil, or between the soil itself, and by the crushing of soil particles.

For example, in the case of clay, the sound is so weak that it is almost inaudible.

Sand makes a crunching sound, and gravel makes a rasping sound. Similar to this, vibration acceleration with a different waveform is generated depending on the particle size of the soil, and if this vibration acceleration is detected by the acceleration sensor 53 built in the cone 52 and the waveform is analyzed, it is possible to detect the vibration acceleration of the soil particles. It is possible to determine the diameter to some extent.

FIG. 12 shows an example of a device that processes the output signal from the acceleration sensor 53 described above. As shown in the figure, the output signal from the acceleration sensor 53 is transmitted to the processing device 5.
After being amplified by an amplifier 57 in 6, it is converted to an effective value by an effective value converter 58, and sent to a microcomputer 60 as a digital signal via an A/D converter 59. Further, the output signal from the load sensor 54 is also transmitted to the amplifier 61.
, microcomputer 60 via A/D converter 59
will be sent to. And the microcomputer 60
Based on the relationship between the waveform characteristic data (vibration characteristic data) of the output signal of the acceleration sensor 53 and the penetration resistance data based on the output signal of the load sensor 54, soil quality information such as the soil particle size or grain size is calculated.

This is displayed on the display 62.

Note that instead of the acceleration sensor 53, a vibration sensor such as a microphone that detects sound or an AE sensor that detects acoustic emissions (AE) may be provided.

FIG. 13 is a graph diagram for explaining the soil information calculation process executed by the microcomputer 60.

The vertical axis of the figure represents the effective value level Vmean of vibration acceleration,
The horizontal axis represents the penetration resistance F, respectively. As is clear from the figure, in any soil type, as the penetration resistance F increases, the effective value level Vmean of vibration acceleration increases approximately linearly, and the increment in the effective value level (the slope of the straight line in the figure) varies depending on the soil type. The difference is that the larger the soil particle size, the larger the slope.

Therefore, if the relationship between the effective value level Vmean of vibration acceleration determined for each soil particle size and the penetration resistance F is determined in advance through experiments (only a few examples are shown in Fig. 13, for example, ), the effective value level Viea
When n and penetration resistance F are given, the soil particle size Dso can be easily determined from the relationship shown in the diagram. In addition, on the intersection of the effective value level Vmean and the penetration resistance F, the grain size I)s
If o is not multiplied, the most approximate particle size is calculated.

This particle size calculation method is based on the fact that the larger the particle size, the larger the amplitude of vibration acceleration, and the relationship between the change in vibration due to particle size and the compactness (density, confining pressure) of the soil. This is based on the research results of the present inventors who found that there is a certain relationship (the relationship shown in Figure 13).
No. 2610.

Patent Application No. 112611/1982, Patent Application No. 84143/1983
The details are shown in Japanese Patent Application No. 63-84144, and the particle size of soil can be similarly determined by a method of accumulating the fluctuations in the effective value of vibration. Furthermore, as proposed in Japanese Patent Application No. 63-84144, the particle size of the soil, that is, the state of particle size distribution, can also be determined from the relationship between the determined particle size and the waveform characteristic value of the output signal of the vibration sensor. I can do it.

[Problems to be Solved by the Invention] According to the soil quality determination device as described above, the vibration output detected by the vibration sensor is detected by the penetration resistance that reflects the strength of the soil, such as the density and compactness of the soil. It is possible to correct the influence due to the strength of soil in a preferable manner, and it is possible to determine the grain size of soil with a certain degree of accuracy.

Incidentally, soil particles of various sizes exist in the soil of the original ground, and as the exploration rod penetrates, the soil at the tip of the rod changes, for example, from clay to gravel to sand. If such a change occurs suddenly (for example, from gravel to clay), the output level of the vibration sensor for large-grained gravel is about 102 to 101 times higher than for small-grained clay, so the vibration If the amplification factor of the amplifier that amplifies the sensor output is the optimum amplification factor for gravel, there is a problem that the vibration output signal for clay is too small and buried in noise, making it impossible to detect the effective vibration components unique to clay. . On the other hand, if the amplification factor of the amplifier that amplifies the output of the vibration sensor is optimal for clay, the vibration output signal from gravel will exceed the full scale of the amplifier, making it impossible to detect the signal from gravel. There was a problem. In other words, in the past, no consideration was given to amplifying the output signal of a vibration sensor with an optimal amplification factor depending on the particle size, and accuracy was not achieved over a wide range of particle sizes from clay to gravel. There was a problem in that it was difficult to perform accurate particle size discrimination.

Therefore, the technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art.

The purpose is to provide a soil type discrimination device that can accurately discriminate particle sizes over a wide particle size range from small soil to large particle size soil.

[Means for Solving the Problems] In order to achieve the above-mentioned objects, the present invention provides an exploration rod that penetrates into the soil, a penetration device for penetrating the exploration rod into the soil, and the exploration rod that penetrates the soil. at least one type of vibration sensor built into the exploration rod to detect vibration near the tip of the rod; a load sensor built into the exploration rod to detect penetration resistance applied to the tip of the exploration rod; A soil quality determination device comprising: a calculation processing device that determines at least the grain size of soil based on the relationship between the waveform characteristic value of the output signal of the vibration sensor generated during penetration and the penetration resistance based on the output signal of the load sensor; It is configured so that only the signal obtained by amplifying the output signal of the vibration sensor at an optimum amplification factor is used for soil particle size determination processing.

Further, in the present invention, preferably, an amplification factor control means is provided for controlling an amplification factor of the amplifier for the vibration sensor based on a penetration resistance value by the load sensor, and the amplification factor control means controls the amplification factor of the amplifier for the vibration sensor. The amplification factor is controlled to the optimum amplification factor for soil particle size discrimination processing.

Further, in the present invention, it is preferable that the output signal of the vibration sensor is branched into a plurality of parts and sent to amplifiers each having a different amplification factor for amplification, so that among the outputs of the plurality of amplifiers, the output signal exceeds the maximum output of the amplifier. Also, the signal that does not exceed the input range of the A/D converter and has the highest amplification factor is used for soil particle size discrimination processing.

[Function] The present invention is as described above. For example, the amplification factor of the vibration sensor amplifier is variably controlled based on the penetration resistance value, and
The level of the vibration output signal amplified by the amplifier is made to be the optimal signal level for the waveform signal processing performed at the subsequent stage. Then, the particle size representative of the soil is determined based on the relationship between, for example, the average effective value of the vibration output signal that has reached the optimum signal level and the penetration resistance obtained from the load sensor.

Alternatively, the output signal of the vibration sensor may be branched into multiple parts, each with a different amplification factor (for example, 1x, 10x, etc.).

100 times, 1000 times) to an amplifier for amplification, and among the outputs of the plurality of amplifiers, the one that does not exceed the maximum output of the amplifier or the input range of the A/D converter, and has the highest amplification factor. Extract large signals.

Then, the vibration output signal amplified with this optimum amplification factor,
For example, the particle size representative of soil is similarly determined based on the relationship between the average value of the effective values and the penetration resistance obtained from the load sensor.

By doing this, the amplification factor of the vibration output in clay, for example, is made relatively larger than that in gravel, and the vibration information specific to clay is reliably detected without being buried in noise. The amplification factor of the vibration output in gravel is relatively smaller than that in clay and does not exceed the full scale of the amplifier, making it possible to accurately determine particle size over a wide particle size range. .

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 10.

1 to 9 relate to a first embodiment of the present invention, and FIG. 1 is a block diagram of a soil quality determination device. In Figure 1, l
is an exploration rod, 2 is an acceleration sensor that is a vibration sensor, and 3 is an acceleration sensor that is a vibration sensor.
is a load sensor. As shown in FIG. 2, the exploration rod 1 includes an elongated metal main body 4 and a conical metal cone 5 attached to the tip of the main body 4. The diameter of the cone is approximately 35 to 40 mm.
The tip angle α is set to about 60°.

The acceleration sensor 2 is attached to the cone 5 via an insulating adapter 6 that satisfies the frequency response characteristics of the sensor, and detects the vibration acceleration of the cone 5 when it penetrates into the soil. There is. The load sensor (load cell) 3 is equipped with a strain gauge (not shown) and is attached to the rear end of the cone 5 and the stepped portion 4a on the tip side of the main body 4 so as to be in close contact with each other. The penetrating resistance applied to the cone 5 is detected at this point.

The probe rod 1 is pressed at its rear end by a penetrating device 7 (FIG. 1) consisting of a hydraulic cylinder or the like, and the cone 5 at the tip is pushed into the soil at a constant speed (for example, 1 cm/5ee).
) to be penetrated.

The output signal of the acceleration sensor 2 is input to an amplifier 8. The amplifier 8 is configured such that the amplification factor can be switched in a plurality of stages from 1 to about 1000 times, for example, by a control signal from the amplification factor control means 26, and the amplification factor can be switched as necessary. The output signal from the acceleration sensor 2 is amplified and sent to the effective value converter 9 at the subsequent stage. Further, a signal indicating the amplification factor selected in the amplifier 8 is sent to the effective value calculation processing means 13 of the calculation processing unit 11, which will be described later. The output signal of the load sensor 3 is amplified by an amplifier 12 and sent to a subsequent stage.

A signal level representing the penetration resistance is supplied to the amplification factor control means 26, and the amplification factor control means 26 thereby changes the amplification factor of the amplifier 8. In other words, for gravel with a large penetration resistance value.

The amplification factor of the amplifier 8 is selected and set to be relatively small, and when the penetration resistance is small, such as clay, the amplification factor of the amplifier 8 is set to be relatively large.

The acceleration signal amplified at a predetermined amplification factor by the amplifier 8 is taken into a data recorder (not shown) as required, and then converted into an effective value by an effective value converter 9.
Thereafter, it is converted into a digital signal by the A/D converter 10 and sent to the arithmetic processing unit HII. here,
A signal representing the amplification factor of the amplifier 8 is also not shown, but it can be taken into a data recorder if necessary. Also,
The output signal of the load sensor 3 is amplified by an amplifier 12,
Although not shown, the data is taken into a data recorder as necessary, converted into a digital signal by the A/D converter 10 at an appropriate sampling rate, and sent to the arithmetic processing unit 1W11.

The arithmetic processing device 11 includes an effective value arithmetic processing means 13, a particle size discrimination means 14, a particle size discrimination means 15. It is equipped with a soil classification determination means 16, etc., and uses the waveform characteristic value obtained by calculating the output signal of the acceleration sensor 2 converted into an effective value and the penetration resistance value detected by the load sensor 3 to refer to various tables. As described later, the particle size, grain size, and soil classification of the soil are determined.

The particle size determining means 14 is equipped with a first table 17, and in this embodiment, the first table 17 includes, as described later, predetermined values for each type of soil average particle size Dso that has been studied as a case study. The relationship between the average effective value of the output signal of the acceleration sensor 2 and the penetration resistance is stored. In addition, the first table 17 shows the relationship between the cumulative amplitude value of the above-mentioned effective value determined for each type of soil average particle diameter Dso and the penetration resistance, or the relationship between the effective value (maximum value - average value) and the penetration resistance. You may also store the relationship.

The particle size determining means 15 includes a uniformity coefficient determining means 18 and a particle size accumulation curve calculating means 19, and the uniformity coefficient determining means 18 is provided with a second table 20. The second table 20 includes the soil uniformity coefficient Cu, which is one of the indicators representing the distribution state of the size of soil particles, that is, the particle size DIo corresponding to a 1-pass mass percentage of 10%, and the particle size DIo corresponding to a 1-pass mass percentage of 60%.
The soil uniformity coefficient Cu = D bo / D to expressed as a ratio to the particle size D60 corresponding to % and the standard deviation/average value of the effective value of the output signal of the acceleration sensor 2, or - average value)/(average value - minimum value) is stored.

In addition, the soil quality determining means 16 is equipped with a third table 21, and the third table 21 includes a clay content (particle size of 0.005+++m or less) and a silt content (particle size of 0.005+++ m or less) constituting the soil.
5~0.074ma+), sand content (particle size 0.074mm
Data regarding the soil type classification as shown in FIG. 9, which is determined by the proportion of each of the above) in the total mass, is stored.

The above-mentioned effective value calculation processing means 13 performs calculation processing on the output signal of the acceleration sensor 2, which has been converted into an effective value, with reference to the signal representing the above-mentioned amplification factor sent from the amplifier 8, and calculates the output signal for a predetermined period of time ( For example, the average value of the effective values within 1 second is calculated and sent to the particle size determining means 14, and the standard deviation of the effective values/average value or (maximum value - average value)/(average value) of the effective values is calculated. value - minimum value) and sends it to the equality coefficient determining means 18. Here, the effective value arithmetic processing means 13 refers to the signal representing the above-mentioned amplification factor sent from the amplifier 8, and calculates each effective value level at the point in time when the acceleration sensor 2 detects each effective value level, regardless of the amplification factor. Computational processing is performed that can be evaluated at the output level of . Furthermore, for reference, the standard deviation indicating the variation from the above-mentioned average is expressed as follows.

However, X is the measured value, X is the average value, and n is the measured value (data).
The number of (n-1) is the degree of freedom.

The particle size determining means 14 calculates the average value of the effective value (effective value of vibration acceleration) given from the effective value calculation processing means 13 and the amplifier 12 from the load sensor 3. Based on the penetration resistance given through the A/D converter 10, the average particle diameter D of the soil is determined by referring to the contents of the first table 17.
Determine so.

Further, the equality coefficient determining means 18 calculates the standard deviation/average value of the effective value given from the effective value calculation processing means 13;
Alternatively, the uniformity coefficient Cu is determined by referring to the contents of the second table 20 based on (maximum value - average value)/(average value - minimum value) of the effective value. Further, the particle size cumulative curve calculation means 19 calculates the average particle size Dso and the uniformity coefficient C given by the particle size discrimination means 14 and the uniformity coefficient discrimination means 18.
The particle size cumulative curve is approximated by u. Furthermore, the soil classification determining means 16 calculates the mass ratio of clay, silt, and sand based on the calculation result given from the grain size integration curve calculation means 19, and refers to the third table 21. and determine the soil classification.

Note that the arithmetic processing unit 11 described above is actually composed of a microcomputer, and includes various ■/○ interfaces, a ROM that stores a main control program and various fixed data, a RAM that reads and writes various flags and data, etc. It is equipped with a μCPU (micro central processor unit), etc., which controls the entire system, and performs particle size 1 particle size and soil type classification processing based on predetermined programs and measurement information. Further, the calculation results of the calculation processing unit 11 are sent to an output device such as a CRT display type display 22 or a printer 23 as necessary, so that an operator or the like can visually check the soil information in real time. There is.

Furthermore, the arithmetic processing unit 11 is also connected to an external memory 24 such as a magnetic disk drive, so that necessary data can be stored or retrieved.

Furthermore, the arithmetic processing results of the arithmetic processing device 11 are transmitted to a construction management system 2 that manages and controls the shield construction method, etc.
5 is also supplied in real time, and the construction management system 25 controls and instructs the next construction stage to be the most suitable based on this site soil information.

The explanation will be continued below with reference to FIGS. 3 to 9.

Figure 3 (a), (b), and (c) show clay of different soil types,
The output signals obtained from the acceleration sensor 2 when the exploration rod 1 penetrates into sand and gravel soil are each amplified by different amplification factors in the amplifier 8, and are converted into effective values by an effective value converter 9. This shows the waveform data after converting it to a value. (In addition, all of these data are shown for 1 second.) As is clear from the figure, the effective value of vibration acceleration (hereinafter simply referred to as vibration acceleration) in the order of clay, sand, and gravel.
The fluctuation amplitude of is increasing, and the larger the soil particle size, the larger the amplitude of the vibration acceleration. Also, what is the waveform of vibration acceleration when it penetrates gravel?

The fluctuations are more severe than those of clay and sand, and especially sudden large accelerations are generated. This sudden large acceleration is a phenomenon that occurs when the gravel is disengaged or crushed, and as the gravel becomes larger, the time interval between occurrences of the sudden large acceleration becomes longer. Therefore, when sampling the analog data after effective value conversion with the A/D converter 10, a sufficiently long sampling time 1, for example, about 0.5 seconds or more is required.

As described above, the amplitude of vibration acceleration varies greatly depending on the particle size of the soil, and the larger the particle size, the larger the amplitude. However, even if the soil is the same, if the degree of compaction is different, the level of vibration acceleration will be different, and the amplitude will also be different. Fourth
In order to verify this point, Figures (a), (b), and (C) show the exploration rod 1 using the same sand and changing the density or confining pressure.
This shows the waveform of the vibration acceleration (effective value) when the material is penetrated. As is clear from the figure, it can be seen that as the density or confining pressure increases, the amplitude increases.

In addition, the penetration resistance detected by the load sensor 3 is also increasing accordingly. Therefore, if the influence of soil compaction and the like is corrected by the penetration resistance for a change in amplitude due to one particle size, it becomes possible to determine the particle size with high accuracy.

This correction method is based on a certain correlation determined by the particle size (average particle size D so ) between the average value of the penetration resistance and the vibration acceleration, as shown in FIG. 5 and stated in the earlier application mentioned above. This is done based on the fact that there is a relationship.

Note that in FIG. 5, both the vertical and horizontal axes are expressed on a logarithmic scale. What should be noted in Figure 5 is that as the penetration resistance increases for any soil type (grain size), the average value of vibration acceleration also increases linearly, and the increment (the slope of the straight line in the figure) varies depending on the grain size. The difference is that the slope increases as the soil particle size increases.

Therefore, the relationship between the average value of vibration acceleration and penetration resistance for each average soil particle size OSO should be understood through experimental case studies (only three representative examples are shown in Figure 5, but for example, Every 0.1III of particle size or 0.05+
If you store this in the first table 17 described above, then if the average value of vibration acceleration (output of the effective value calculation processing means 13) and penetration resistance are given, The particle size determining means 14 can immediately determine the accurate particle size and output it. Namely.

The slope of the straight line, which is different for each particle size as shown in FIG.
will be required in real time. It is obvious that when a value that does not fit the slope is calculated, the most approximate average particle size Dso is assigned.

Here, the number determined for each average grain size D so is determined by the relationship between the cumulative amplitude value of the vibration acceleration and the penetration resistance, or by the relationship between the (maximum value - average value) of the vibration acceleration and the penetration resistance. There is a correlation almost similar to that shown in FIG. The cumulative amplitude value or (maximum value - average value) of the vibration acceleration is calculated and supplied to the particle size determining means 14.

Here, the usefulness of changing the amplification factor of the amplifier 8 depending on the output level of the load sensor 3 as described above will be explained. According to FIG. 5, the average value of vibration acceleration increases as the penetration resistance increases for any soil quality (particle size). Therefore, in this embodiment, for example, when the penetration resistance is about 50 Kgf, the full scale of the amplifier 8 is not exceeded, and the input range of the A/D converter 10 is not exceeded.
The amplification factor of amplifier 8 is set so that approximately IG equivalent is maximized, and if the penetration resistance is approximately 500Kgf, it is also approximately 1
By setting the amplification factor of amplifier 8 so that 0G is the maximum, the vibration acceleration signal amplified with the optimum amplification factor can be used for waveform processing even in soil of unknown soil quality (particle size). . On the other hand, while the level of vibration acceleration changes rapidly due to rapid changes in soil quality associated with penetration, changes in penetration resistance are gradual. Therefore, even if the amplification factor of the amplifier 8 is variably set every second, for example, by the value of the penetration resistance for the immediately preceding second, a sufficient effect can be obtained.

Next, we will explain the method for determining soil particle size.

To express the particle size of soil, a semi-logarithmic graph as shown in Figure 6 is generally used, and the particle size is plotted on a logarithmic scale, and the mass percentage of the amount of particles of each particle size relative to the total is plotted on an arithmetic scale. , this relationship is expressed by a curve called a particle size accumulation curve. In addition, as a method of expressing how various particle sizes are mixed according to the slope of this particle size accumulation curve, generally, the particle size D + o corresponding to a passing mass percentage of 10% is used.
and the particle diameter D6o corresponding to a passing mass percentage of 60%.
1o) is used. Therefore, if the average particle size OSO of the soil and the above-mentioned uniformity coefficient Cu are known, an approximate particle size accumulation curve can be obtained based on this, and the soil can be identified by the particle size and grain size. In addition, in FIG. 6, (a).

The particle size accumulation curves shown in (b) and (C), respectively, are for sand (uniformity coefficient Cu = 2.1) and clay (uniformity coefficient Cu = 2.1) used in the experiment.
u=16.2) and sand and gravel (uniformity coefficient Cu=20.0).

Figures 7(a), (b), and (c) show the particle size accumulation curves (a), (b), and (c) shown in Figure 6 for each soil consisting of sand, clay, and gravel. 2 shows a waveform after converting the output signal of the acceleration sensor 2 into an effective value level when the exploration rod 1 penetrates. As is clear from the figure, unlike the waveforms in sand, sudden large accelerations considerably larger than the average level occur randomly in clay and gravel where the uniformity coefficient Cu is larger than that in sand. . Therefore, the uniformity coefficient Cu can be predicted by paying attention to the magnitude and frequency of sudden large accelerations that occur when the exploration rod 1 penetrates soil with a large uniformity coefficient Cu, such as clay or gravel. That is, if we focus on the standard deviation/average value of vibration acceleration or (maximum value - average value)/(average value - minimum value) of vibration acceleration, the uniformity coefficient Cu can be calculated as described later.
can be calculated.

The following explanation will be made using the standard deviation/average value of vibration acceleration as an example, but (maximum value - average value) of vibration acceleration
The case of /(average value−minimum value) is also a road difference.

In FIG. 8, the vertical axis shows the standard deviation/average value of vibration acceleration converted to an effective value, and the horizontal axis shows the uniformity coefficient Cu, and both the vertical and horizontal axes are shown on a logarithmic scale. As is clear from the figure, compared to sand where the level of vibration acceleration is steady and the uniformity coefficient Cu is small, sudden large accelerations occur, and the waveform level of the vibration acceleration fluctuates greatly and the uniformity coefficient C
It can be seen that in clay and gravel with a large u, the standard deviation/average value mentioned above becomes large. Also, in the same figure, sand and clay.

The length of the solid line shown on the gravel indicates the range of data variation, the 0 mark shows the average of multiple data, and each plot of O marks almost converges on a straight line with a constant slope shown by the dotted line in the figure. ing. Therefore, as the uniformity coefficient Cu becomes larger, the standard deviation/average value of the vibration acceleration becomes larger, and this almost lies on a straight line with a constant slope, so if this relationship is stored in the second table 20, The uniformity coefficient determination means 18 can determine the uniformity coefficient Cu by being given the standard deviation/average value of vibration acceleration. At this time, it is desirable that the standard deviation/average value data is obtained by averaging a plurality of pieces of data, and it is obvious to those skilled in the art that this process can be easily performed by the effective value calculation processing means 13. be. Further, although only three representative examples are shown in FIG. 8, for example, a case study is made in advance of experimental values each time the uniformity coefficient Cu increases by 1, and this known data is stored in the second table 20. . In addition, in this series of processing, the standard deviation is divided by the average value of vibration acceleration that reflects the particle size, so the relationship shown in FIG. 8 does not differ depending on the particle size or compactness of the soil.

Then, as described above, the average particle diameter D s of the soil
o and the uniformity coefficient Cu are calculated and determined, the average particle diameter D s
Plot o at the corresponding position (see the 0 mark in Figure 6), and draw a straight line passing through the 0 mark (see the two-dot chain line in Figure 6) with a slope based on the obtained uniformity coefficient Cu. This results in a particle size shipping curve of . Therefore, the particle size shipping curve calculating means 19 calculates the given average particle size D so
Based on the uniformity coefficient Cu, the particle size shipping curve is approximately calculated using the method described above. In this way, the approximate particle size shipping curve indicating the particle size and the particle size information obtained by processing this as appropriate are sent to the arithmetic processing device 1 along with the determined average particle size Dso.
1 to the display device 22, printer 23 . External memory 24. It is output to the construction management system 25 or the like.

In addition, when linearly approximating the particle size shipping curve from the relationship between particle size and uniformity coefficient CU, the given particle size does not necessarily have to be the average particle size nso, for example, by calculating D3o,
It can also be determined from this and the estimated value of the calculated uniformity coefficient Cu.

When the approximate particle size shipping curve is determined as above,
Mass percentage of clay, silt, and sand in the total mass of soil
can be calculated, and the soil classification determining means 16 refers to the contents of the third table 21 described above to determine the soil classification based on triangular coordinates, which are often used for soil classification as shown in FIG.

FIG. 10 is a block diagram of a soil quality determination device according to a second embodiment of the present invention. In the figure, the same reference numerals are given to the same components as in the first embodiment, and the explanation thereof will be omitted to avoid duplication. In the same figure, 30 is an amplifier group for amplifying the output of the acceleration sensor 2, and the output signal from the acceleration sensor 2 is branched and input to amplifiers in the amplifier group 30, each having a different amplification factor. Ru. In this embodiment, the amplifier group 30 includes four amplifiers 30a, 30b, 30c, and 30d, each having an amplification factor of 1, 10, 100, and 1000, respectively. The vibration acceleration signals amplified by different amplification factors at ~30d are each independently converted into effective values by the effective value converter 31. Thereafter, each effective value signal sent from the effective value converter 31 is converted into a digital signal at an appropriate sampling rate by the A/D converter 32 and sent to the optimum signal selection means 33. The optimal signal selection means 33 compares and examines each of the sent signals, and selects a signal that does not exceed the maximum output of each amplifier 30a to 30d, does not exceed the input range of the A/D converter 32, and has the highest amplification factor. selects only the effective value signal with a large vibration acceleration and supplies it to the effective value calculation processing means 13 of the calculation processing bag rIll. Furthermore, the optimal signal selection means 33 also sends a signal representing the amplification factor of the signal selected as described above to the effective value calculation processing means 13. Then, the effective value arithmetic processing means 13 converts the selected and sent effective value signal to a signal representing the amplification factor of the signal. Grain size and soil classification are determined.

First mentioned above. In the second embodiment, the acceleration sensor 2
The detected vibration acceleration is amplified at the optimum amplification factor according to the level of each vibration acceleration within a range that does not exceed the full scale of the amplifier and the input range of the A/D converter, and is used for processing such as particle size determination. Even in soils such as clay with low penetration resistance and small particle size, acceleration vibrations with small signal levels can be detected and identified without being buried in noise, and particle size can be reliably determined. I can do it. Also, even if the gravel has a large penetration resistance and a large particle size, the signal level will exceed the amplifier's maximum output and A.
It is possible to avoid the situation where the input range of the /D converter is exceeded and the measurement becomes impossible, and it is possible to determine the particle size with high accuracy over a generally wide particle size range6. An example of converting the output signal of the sensor 2 into an effective value was shown. The reason for this is that using the effective value allows us to accurately capture the fluctuations in vibration amplitude over time.

This is to convert the output signal of the acceleration sensor 2 into a smooth waveform that follows the main waveform as much as possible, lower the frequency, and reduce the number of samplings to increase the data processing speed.

However, the same processing can be performed even if the output signal main waveform of the acceleration sensor 2 is directly A/D converted. In addition, although the acceleration sensor 2 is used as the vibration sensor, even if other vibration sensors such as a microphone or AE (acoustic emission) sensor are used,
Using the same principle, soil particle size, grain size, and soil type classification can be determined.

Furthermore, it is also possible to use a combination of a plurality of different types of sensors, such as an acceleration sensor and an AE sensor.

[Effects of the Invention] As detailed above, according to the present invention, in a soil type determination device that can determine soil quality information such as soil particle size in real time, it is possible to determine soil quality information such as soil particle size over a wide range of particle sizes from clay to gravel. We can provide a device that is capable of highly accurate particle size discrimination, and can be used in construction management of civil engineering works, etc., to quickly set optimal construction conditions.

Its industrial value is enormous.

[Brief explanation of drawings]

1 to 9 relate to the first embodiment of the present invention, in which FIG. 1 is a block diagram of the soil quality determination device, FIG. 2 is a sectional view of the tip of the exploration rod, FIG. 3(a), (b) and (c) are effective value waveform diagrams of vibration acceleration for various soil types, and Figure 4 (a)
, (b) and (c) are effective value waveform diagrams of vibration acceleration to explain waveform changes due to soil compaction, etc. in the same soil type, and Figure 5 shows the average value of the effective value of vibration acceleration and penetration by soil type. Graph showing the relationship with resistance, Figure 6 is a graph showing the particle size shipping curve, Figure 7 (a), (b), Cc,)
are graphs showing waveforms of vibration acceleration converted to effective values when penetrating soils with different uniformity coefficients, FIG. 8 is a graph showing the relationship between standard deviation/average value of vibration acceleration and uniformity coefficients, FIG. 9 is a graph diagram showing soil quality classification using triangular coordinates, FIG. 10 is a block diagram of a soil quality discrimination device according to a second embodiment of the present invention, FIGS. 11 to 13 are related to a conventional example, and FIG. is a cross-sectional view of the tip of the exploration rod, No. 12
The figure is a block diagram of the processing device, and FIG. 13 is a graph showing the relationship between the effective value level of vibration acceleration and penetration resistance for each soil type. 1...Exploration rod, 2...Acceleration sensor (vibration sensor), 3...Load sensor, 4...
...Body part. 5... Cone, 6... Insulation adapter,
7...Penetration device, 8...Amplifier, 9.
... Effective value converter, 10 ... A/D converter, 11 ... Arithmetic processing unit, 12 ...
...Amplifier, I3...Effective value calculation processing means, 1
4... Particle size discrimination means, 15... Particle size discrimination means, 16... Soil classification discrimination means, 17...
. . . 1st table, 18 . . . Uniformity coefficient determination means, 19 .
...Second table, 21...Third table, 22...Display unit, 23...Printer, 24...External memory, 25 ...Construction management system, 26...Amplification factor control means, 3
0...Amplifier group, 30a to 30d...
Amplifier, 31... Effective value converter, 32...
...A/D converter, 33...optimum signal selection means. Figure M (seconds) Formula (seconds) Time (seconds) rd: Dry density p: Confining pressure (G) Figure Penetration resistance (kgf) Figure Uniformity coefficient Cu Figure Silt minute (Z> Figure 1i Figure 1 Figure 13 Gravel large penetration resistance F

Claims (3)

[Claims] (1) An exploration rod that penetrates into the soil, a penetration device for penetrating the exploration rod into the soil, and at least one device built into the exploration rod to capture vibrations near the tip of the exploration rod. one type of vibration sensor, a load sensor built into the exploration rod to detect penetration resistance applied to the tip of the exploration rod, a waveform characteristic value of an output signal of the vibration sensor generated when the rod penetrates, and the load sensor. In the soil quality determination device, which is equipped with at least a calculation processing device that determines the particle size of soil based on the relationship with the penetration resistance based on the output signal of the vibration sensor, only a signal obtained by amplifying the output signal of the vibration sensor with an optimal amplification factor is used. A soil quality determination device characterized in that it is used for soil particle size determination processing. (2) In claim 1, further comprising: an amplification factor control means for controlling an amplification factor of an amplifier for the vibration sensor based on a penetration resistance value by the load sensor; A soil type discrimination device characterized in that the amplification factor of the amplifier is controlled to an optimum amplification factor for soil particle size discrimination processing. (3) In claim 1, the output signal of the vibration sensor is branched into a plurality of parts and sent to amplifiers with different amplification factors for amplification, and the output signal exceeds the maximum output of the amplifier among the outputs of the plurality of amplifiers. A soil type discriminating device characterized in that a signal having the highest amplification factor without exceeding the input range of an A/D converter is used for soil particle size discriminating processing.