Soil quality measurement method and soil quality measurement device

Abstract

To provide a soil property measuring method and a soil property measuring device allowing improvement of efficiency.SOLUTION: Electric resistance of a ground material S is measured in an electric resistance measuring process. Dry density of a soil part of the ground material S is derived, in a soil part dry density derivation process, through the electric resistance of the ground material S measured in the electric resistance measuring process and a predetermined relation between an electric resistance of the soil part where gravel fractions / stones G are removed from the ground material S and dry density. Dry density of the ground material S is derived, in a total dry density derivation process, based on the dry density of the soil part of the ground material S derived in the soil part dry density derivation process, density of the gravel fractions / stones G of the ground material S, and content percentage of the gravel fractions / stones as a mass ratio of the gravel fractions / stones G in the mass of the ground material S. This allows labor saving in an indoor test and improvement of efficiency because of no need for acquiring electrical conductance per grain size and content percentage of the gravel fractions / stones G in the ground material S during the indoor test.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a soil measurement method and a soil measurement device. [Background technology]

[0002] A technique has been proposed for measuring the soil quality of a ground material by measuring its electrical resistance using electrodes in contact with the ground material. For example, Patent Document 1 discloses a technique in which the lower ends of multiple vertically extending rod-shaped electrodes are pressed against ground material that has been compacted with a roller to measure the electrical resistance of the ground material, thereby obtaining the degree of compaction of the ground material based on a predetermined relationship between the measured electrical resistance of the ground material and its dry density. The relationship between the electrical resistance of the ground material and its dry density is shown by a graph curve (calibration curve) with electrical resistance and dry density as parameters. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-062362 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned technology, when gravel and stone are present in the ground material, the influence of the gravel and stone is too great in the laboratory tests to obtain the calibration curve, resulting in variations in the calibration curve. Furthermore, the calibration curve must be obtained for each ground material at each site. However, as mentioned above, the calibration curve varies depending on the particle size and content of the gravel and stone in the ground material. Therefore, in order to obtain the calibration curve, it is necessary to perform laboratory tests for each particle size and content of the gravel and stone, which differ depending on the ground material. This results in low efficiency of laboratory tests.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a soil quality measurement method and a soil quality measurement device that can improve efficiency. [Means for solving the problem]

[0006] The present invention comprises an electrical resistance measurement step of measuring the electrical resistance of a ground material, a soil portion dry density derivation step of deriving the dry density of the soil portion of the ground material based on the electrical resistance of the ground material measured in the electrical resistance measurement step and a predetermined relationship between the electrical resistance and dry density of the soil portion from which gravel and stone components have been removed from the ground material, and an overall dry density derivation step of deriving the dry density of the ground material based on the dry density of the soil portion of the ground material derived in the soil portion dry density derivation step, the densities of the gravel and stone components of the ground material, and the gravel and stone content, which is the ratio of the mass of the gravel and stone components to the mass of the ground material. In a preliminary laboratory test, a specimen in which gravel and stone have been removed from the on-site ground material is used, and a predetermined relationship between the electrical resistivity and dry density of the soil portion from which gravel and stone have been removed is obtained as a single calibration curve.The dry density of the on-site ground material is obtained by applying the resistivity of the ground material measured on-site in the electrical resistivity measurement process to the single calibration curve obtained. This is a soil quality measurement method.

[0007] According to this configuration, the electrical resistance of the ground material is measured in the electrical resistance measurement step. Based on the inventor's knowledge, in ground materials containing gravel and stone, the electrical resistance of the ground material is believed to depend only on the electrical resistance of the soil portion from which the gravel and stone have been removed, and not on the state of the gravel and stone. Therefore, in the soil portion dry density derivation step, the dry density of the soil portion of the ground material is derived based on the electrical resistance of the ground material measured in the electrical resistance measurement step and a predetermined relationship between the electrical resistance and dry density of the soil portion from which the gravel and stone have been removed. In the overall dry density derivation step, the dry density of the ground material is derived based on the dry density of the soil portion of the ground material derived in the soil portion dry density derivation step, the density of the gravel and stone content of the ground material, and the ratio of the mass of the gravel and stone content to the mass of the ground material. This eliminates the need to obtain calibration curves for each particle size and content of gravel and stone in ground materials during indoor testing, thereby reducing the labor required for indoor testing and improving efficiency.

[0008] In this case, in the whole dry density derivation step, the dry density ρ of the soil part of the ground material derived in the soil part dry density derivation step is ds and the bone-dry density ρ of the gravel and stone components of the ground materialdg and the gravel fraction content P, ρ d =ρ ds ρ dg / {P·ρ ds +(1-P)·ρ dg The dry density ρ of the ground material satisfies d It is preferable to derive

[0009] According to this configuration, in the whole dry density deriving step, the dry density ρ of the soil part of the ground material derived in the soil part dry density deriving step is ds and the bone-dry density ρ of the gravel and stone components of the ground material dg and the gravel content P, the Walker-Holtz grain size correction formula ρ d =ρ ds ρ dg / {P·ρ ds +(1-P)·ρ dg}, the dry density ρ of the ground material d is derived, the dry density ρ of the ground material can be calculated by simple calculation. d can be derived.

[0010] In addition, in the electrical resistance measuring step, it is preferable to measure the electrical resistance of the ground material by using electrodes that move over the ground material and come into contact with the ground material.

[0011] According to this configuration, in the electrical resistance measurement process, the electrical resistance of the ground material is measured using electrodes that move over the ground material and contact the ground material, so that the dry density of a wider range of ground material can be derived within the same amount of time.

[0012] Preferably, gravel is soil particles contained in the ground material with a particle size of 2 mm or more and less than 75 mm, and stone is soil particles contained in the ground material with a particle size of 75 mm or more.

[0013] According to this configuration, gravel is soil particles with a particle size of 2 mm or more but less than 75 mm contained in the ground material, and stone is soil particles with a particle size of 75 mm or more contained in the ground material. Based on the inventor's knowledge, in ground materials containing gravel and stone, the electrical resistance of the ground material is believed to depend only on the electrical resistance of the soil portion from which the gravel and stone have been removed. Furthermore, since both gravel and stone are specified in the Japanese Industrial Standard (JIS A 0207), efficiency can be further improved by using a soil quality measurement method that complies with the Japanese Industrial Standard.

[0014] The present invention also provides a ground material measuring device comprising: an electrical resistance measuring unit that measures the electrical resistance of a ground material; a soil portion dry density deriving unit that derives the dry density of the soil portion of the ground material based on the electrical resistance of the ground material measured by the electrical resistance measuring unit and a predetermined relationship between the electrical resistance and dry density of a soil portion from which gravel and stone components have been removed from the ground material; and an overall dry density deriving unit that derives the dry density of the ground material based on the dry density of the soil portion of the ground material derived by the soil portion dry density deriving unit, the density of the gravel and stone components of the ground material, and the gravel and stone content, which is the ratio of the mass of the gravel and stone components to the mass of the ground material. In a preliminary laboratory test, a specimen in which gravel and stone have been removed from the on-site ground material is used, and a predetermined relationship between the electrical resistivity and dry density of the soil portion from which gravel and stone have been removed is obtained as a single calibration curve.The electrical resistivity measurement unit then applies the resistivity of the ground material measured on-site to the single calibration curve obtained to obtain the dry density of the on-site ground material. This is a soil quality measurement device.

[0015] In this case, the whole dry density calculation unit calculates the dry density ρ of the soil part of the ground material calculated by the soil part dry density calculation unit. ds and the bone-dry density ρ of the gravel and stone components of the ground material dg and the gravel fraction content P, ρ d =ρ ds ρ dg / {P·ρ ds +(1-P)·ρ dg}, the dry density ρ of the ground material d It is preferable to derive

[0016] It is also preferable that the electrical resistance measuring unit measures the electrical resistance of the ground material by using electrodes that move over the ground material and come into contact with the ground material. [Effects of the Invention]

[0017] The soil quality measurement method and soil quality measurement device of the present invention can improve efficiency. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1A is a plan view showing the configuration of a soil property measuring device according to an embodiment, and FIG. 1B is a side view showing the configuration of the soil property measuring device according to an embodiment. [Figure 2] 2 is a block diagram showing the functional configuration of a central frame section in FIG. 1. FIG. [Figure 3] 1 is a flowchart showing the steps of soil measurement according to an embodiment. [Figure 4] 1 is a graph showing the relationship between dry density and electrical resistivity of ground materials. [Figure 5] FIG. 1 is a diagram showing the current flowing through the ground material. [Figure 6] (A) is a graph showing the relationship between the dry density of the soil and electrical resistivity, (B) is a diagram showing ground material with a high gravel and stone content, (C) is a diagram showing ground material with a lower gravel and stone content than (B), and (D) is a diagram showing ground material with the same gravel and stone content as (C) but with smaller particle size of the gravel and stone. [Figure 7] FIG. 1 shows the composition of ground materials containing gravel and stone. [Figure 8] (A) is a graph showing the relationship between the dry density and electrical resistivity of the entire ground material for each particle size and content of gravel and stone, and (B) is a graph showing the relationship between the dry density and electrical resistivity of the soil part of the ground material for each particle size and content of gravel and stone. [Figure 9] (A) is a graph showing the relationship between the dry density and electrical resistivity of the entire ground material for each particle size and content of gravel and stone, and (B) is a graph showing the relationship between the dry density and electrical resistivity of the soil part of the ground material for each particle size and content of gravel and stone. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention relates to a soil measurement method and a soil measurement device, and more particularly to a soil measurement device for measuring the electrical resistance of a soil material after compaction by a compaction machine such as a road roller, and to a soil measurement method for measuring the dry density of the soil material, which is correlated with the electrical resistance, in order to confirm the effectiveness of compaction by the compaction machine.

[0020] As shown in Figures 1(A) and 1(B), the soil measurement device 1 of the first embodiment of the present invention includes a central frame unit 4 and an electrode unit 5 towed by the central frame unit 4. The central frame unit 4 has drive wheels 6 for moving the soil measurement device 1 over the ground material S. The drive wheels 6 are driven to rotate by an electric motor, an internal combustion engine, or the like. This allows the soil measurement device 1 of this embodiment to move on its own in direction X over the ground material S.

[0021] The electrode unit 5 contacts the surface of the ground material S. The electrode unit 5 has auxiliary wheels 7 and a towing body 8 that is towed by the central frame unit 4. The electrode unit 5 has four wheel-shaped electrodes 9 at the rear of the towing body 8. The outer peripheral surfaces of the wheel-shaped electrodes 9 contact the surface of the ground material S. As a result, the wheel-shaped electrodes 9 of the electrode unit 5 contact the ground material S while moving over it. The diameter of the wheel-shaped electrodes 9 is, for example, 100 mm to 200 mm. The width in the direction Y perpendicular to the direction X in which the electrode unit 5 of the wheel-shaped electrode 9 moves over the ground material S is, for example, 10 mm to 30 mm. The ground contact length in the direction X in which the electrode unit 5 of the wheel-shaped electrode 9 moves over the ground material S is, for example, 20 mm to 30 mm.

[0022] The spacing between the electrode units 5 of the wheel-shaped electrode 9 in the direction Y perpendicular to the direction X in which they move through the ground material S can be freely changed, for example, to 200 mm, 300 mm, or 750 mm. The four wheel-shaped electrodes 9, each with an electrode unit 5 as described above, are arranged in parallel in the direction Y perpendicular to the direction X in which the electrode unit 5 of the soil measuring device 1 moves through the ground, along the surface of the ground material S, and the electrical resistance of the ground material S is measured, for example, by the Wenner method.

[0023] The contact area and contact time between the wheel-shaped electrode 9 and the surface of the ground material S, which can reduce measurement error, are thought to vary depending on the soil at each work site. Therefore, the central frame 4 with the drive wheels 6 can adjust the speed at which the wheel-shaped electrode 9 moves, allowing it to be set to a speed appropriate for each work site. A faster speed for the wheel-shaped electrode 9 is preferable, as this shortens the time required for measurement. The wheel-shaped electrode 9 may be moved by towing the soil measurement device 1 with a self-propelled compaction machine such as a road roller, an electric stand-on two-wheeler, or by human power. The wheel-shaped electrode 9 may also be moved by integrating the soil measurement device 1 with a self-propelled compaction machine such as a road roller.

[0024] As shown in Fig. 2, the central frame section 4 has an ECU 10, a positioning section 14, a communication section 15, and a drive section 16. The ECU (Electronic Control Unit) 10 is an electronic control unit having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive), etc. The ECU 10 includes an electrical resistance measurement section 11, a soil dry density calculation section 12, and an overall dry density calculation section 13. The ECU 10 loads a program stored in the ROM into the RAM and executes it on the CPU, thereby controlling each section, such as the electrical resistance measurement section 11.

[0025] The electrical resistance measurement unit 11 measures the electrical resistance of the ground material S using the four wheel-shaped electrodes 9 of the electrode unit 5. Therefore, the electrical resistance measurement unit 11 measures the electrical resistance of the ground material S using the wheel-shaped electrodes 9 that move over the ground material S and come into contact with the ground material S. When the electrical resistance measurement unit 11 measures the electrical resistance of the ground material S, it means, for example, calculating the resistivity of the ground material S. Note that when the electrical resistance measurement unit 11 measures the electrical resistance of the ground material S, it does not necessarily mean only calculating the numerical value of the electrical resistance or resistivity of the ground material S, but also includes, for example, outputting information regarding the current value and voltage value detected by the electrode unit 5.

[0026] The soil dry density deriving unit 12 derives the dry density of the soil portion of the ground material S from the electrical resistivity of the ground material S measured by the electrical resistivity measuring unit 11 and a predetermined relationship between the electrical resistivity and dry density of the soil portion from which gravel and stone have been removed from the ground material S. Here, gravel refers to soil particles contained in the ground material S with a particle size of 2 mm or more and less than 75 mm. Stone refers to soil particles contained in the ground material S with a particle size of 75 mm or more. These gravel and stone components are both specified in the Japanese Industrial Standard (JIS A 0207). The predetermined relationship between the electrical resistivity and dry density of the soil portion will be described later.

[0027] The overall dry density deriving unit 13 derives the overall dry density of the ground material S based on the dry density of the soil portion of the ground material S derived by the soil portion dry density deriving unit 12, the density of the gravel and stone portions of the ground material, and the gravel and stone content, which is the ratio of the mass of the gravel and stone portions to the mass of the ground material S. Details of the method for deriving the overall dry density of the ground material S will be described later.

[0028] The positioning unit 14 measures the position of the wheel-shaped electrode 9, for example, by GNSS (Global Navigation Satellite System) measurement. In GNSS measurement, the position of the wheel-shaped electrode 9 (for example, the latitude and longitude of the wheel-shaped electrode 9) is measured by receiving signals from three or more satellites. Instead of GNSS measurement, the position of the wheel-shaped electrode 9 may be measured by an automatic tracking Total Station (TS) using an optical measurement function.

[0029] The communication unit 15 is a receiving unit that receives command signals to the ECU 10 and the drive unit 16 from outside the soil measurement device 1. As a result, the operations of the ECU 10 and the drive unit 16 are remotely controlled. The communication unit 15 transmits information about the overall dry density of the ground material S derived by the overall dry density derivation unit 13 of the ECU 10 and information about the position of the wheel-shaped electrode 9 measured by the positioning unit 14. The information about the overall dry density of the ground material S derived by the overall dry density derivation unit 13 and information about the position of the wheel-shaped electrode 9 measured by the positioning unit 14 may be recorded in a recording device mounted on the soil measurement device 1 in association with each other.

[0030] The driving unit 16 drives the driving wheels 6 based on the command signal received by the communication unit 15, and moves the soil measuring device 1 to any location on the ground material S. The driving unit 16 may also move the soil measuring device 1 to any location on the ground material S based on a preset route.

[0031] The soil measurement method of this embodiment will be described below. As shown in Fig. 3, an electrical resistance measurement step of measuring the electrical resistance of a ground material S is carried out by the electrical resistance measurement unit 11 of the soil measurement device 1 (S1). In the electrical resistance measurement step, as the soil measurement device 1 moves, the electrical resistance of the ground material S is measured by the wheel-shaped electrode 9 that moves over the ground material S and comes into contact with the ground material S.

[0032] The soil portion dry density derivation unit 12 of the soil measuring device 1 executes a soil portion dry density derivation step in which the dry density of the soil portion of the ground material S is derived from the electrical resistivity of the ground material S measured in the electrical resistivity measurement step and a predetermined relationship between the electrical resistivity and dry density of the soil portion from which gravel and stone have been removed from the ground material S (S2). The entire dry density derivation unit 13 of the soil measuring device 1 executes an entire dry density derivation step in which the dry density of the ground material S is derived based on the dry density of the soil portion of the ground material S derived in the soil portion dry density derivation step, the densities of the gravel and stone components of the ground material S, and the gravel and stone content, which is the ratio of the mass of the gravel and stone components to the mass of the ground material S (S3). The soil portion dry density derivation step and the entire dry density derivation step will be described in detail below.

[0033] The development of automation for heavy machinery construction in earthworks is accelerating. However, quality control after construction is still performed using conventional methods, such as the sand replacement method and the RI method, with manual measurement and discrete data. Aiming to automate the entire earthworks process, the automation of quality control is also urgently needed. As an automatic and total quantitative quality evaluation method to replace conventional methods, a technology for measuring the soil quality of ground materials by measuring their electrical resistivity, as in Patent Document 1, is promising. With this technology, the resistivity of the ground material is obtained by passing an electric current through the ground material after construction and measuring the difference between the current and the potential. The density of the constructed ground is obtained by converting the resistivity of the ground material to the dry density of the ground material.

[0034] In order to convert the resistivity of a geomaterial into its dry density, it is necessary to obtain a resistivity-dry density relationship (calibration curve) for the on-site geomaterial through prior laboratory testing, such as that shown in Figure 4. In this laboratory test, a test specimen is prepared using, for example, a cylindrical calibration curve acquisition device, with the dry density as a parameter, and the resistivity of the test specimen is calculated by passing an electric current through the test specimen and measuring the current and potential difference. However, in the conventional method, obtaining a calibration curve requires laboratory testing for each particle size and content of gravel and stone, which differ depending on the geomaterial, and as mentioned above, the efficiency of laboratory testing is low.

[0035] Meanwhile, as shown in Figure 5, when measuring the electrical resistance of ground material S containing gravel and stone G using electrode 19 and electrical resistance measuring device 21, it has been revealed by the inventor's research that current C does not flow through the gravel and stone G, which has a relatively high electrical resistance, as shown by the dashed line, but bypasses the gravel and stone G, which has a relatively high electrical resistance, as shown by the solid line, and selectively flows through the sand and clay parts, which have lower electrical resistance. In ground material S, the sand and clay parts are soil particles with a particle size of less than 2 mm contained in the ground material, and will be referred to as the soil parts hereinafter.

[0036] Therefore, for ground material S containing gravel and stone G, the resistivity of ground material S is considered to depend only on the resistivity of the soil portion. In other words, for ground material S containing gravel and stone G, the resistivity of ground material S is considered to depend only on the dry density of the soil portion. Therefore, it can be organized by the resistivity-dry density relationship of the soil portion as shown in Figure 6(A), and this resistivity-dry density relationship of the soil portion is independent of the particle size and content of the gravel and stone portions.

[0037] For example, the particle size of the gravel and stone components G in the geomaterial S shown in Figure 6(B) is the same as that of the geomaterial S shown in Figure 6(C), but the content of the gravel and stone components G is higher. In this case, if the overall dry density of the geomaterial S in Figure 6(B) and the overall dry density of the geomaterial S in Figure 6(C) are equal, the content of the gravel and stone components G in the geomaterial S in Figure 6(B) is larger than that in the geomaterial S in Figure 6(C), and the density of the gravel and stone components G is higher than that in the geomaterial S in Figure 6(C). Therefore, the dry density of the soil part of the geomaterial S in Figure 6(B) is lower than that of the soil part of the geomaterial S in Figure 6(C). In this case, due to the resistivity-dry density relationship of the soil part in Figure 6(A), the overall resistivity of the geomaterial S in Figure 6(B) is higher than that of the geomaterial S in Figure 6(C).

[0038] Furthermore, if the dry density of the soil portion of geomaterial S in Figure 6(B) is equal to the dry density of the soil portion of geomaterial S in Figure 6(C), the overall resistivity of geomaterial S in Figure 6(B) will be equal to the overall resistivity of geomaterial S in Figure 6(C). Geomaterial S in Figure 6(B) has a higher content of gravel and stone G than geomaterial S in Figure 6(C), and the density of gravel and stone G is considered to be higher than that of geomaterial S in Figure 6(C). Therefore, the overall dry density of geomaterial S in Figure 6(B) is considered to be higher than the overall dry density of geomaterial S in Figure 6(C).

[0039] On the other hand, the particle size of the gravel and stone components G in the geomaterial S shown in Figure 6(D) is smaller than that of the geomaterial S shown in Figures 6(B) and 6(C), and the content of the gravel and stone components G in the geomaterial S shown in Figure 6(C) is equal to that of the geomaterial S shown in Figure 6(C). In this case, when the overall resistivity of the geomaterial S in Figure 6(C) is equal to that of the geomaterial S in Figure 6(C), the dry density of the soil part of the geomaterial S in Figure 6(C) is considered to be equal to that of the geomaterial S in Figure 6(D). Since the content of the gravel and stone components G in the geomaterial S shown in Figure 6(C) is equal to that of the geomaterial S shown in Figure 6(D), the density of the gravel and stone components G in the geomaterial S shown in Figure 6(D) is also considered to be equal to that of the geomaterial S in Figure 6(D). Therefore, the overall dry density of the geomaterial S in Figure 6(C) is considered to be equal to that of the geomaterial S in Figure 6(D). As described above, the relationship between resistivity and dry density of the soil can be organized.

[0040] In the ground material containing gravel and stone as shown in Figure 7, the mass of soil in the soil part m s , mass of water m ws and the mass of air m a The mass of air m a can be ignored as 0. The dry density of the soil ρ ds In this case, the volume of the soil part is V s is V s =m s / ρ ds In the gravel and stone portion, the mass of the gravel and stone m g and the mass of water m wg The bone dry density of the gravel and stone components is ρ dgIn this case, the volume of gravel and stone V g is V g =m g / ρ dg The total dry density of the geomaterial is ρ d and the dry density of the soil part of the ground material ρ ds and are calculated by the following formulas (1) and (2), respectively. ρ d =(m s +m g ) / (V s +V g ) …(1) ρ ds =m s / V s …(2)

[0041] When laboratory tests are conducted on various specimens using the gravel and stone content and particle size as parameters, and the resistivity-overall dry density relationship of the ground material is obtained using equation (1), the result is, for example, as shown in Figure 8(A). In other words, various curves are drawn depending on the gravel and stone content and particle size. On the other hand, when the horizontal axis of Figure 8(A) is converted using equation (2) and the graph is rearranged according to the dry density of the soil portion, the result is as shown in Figure 8(B). It can be confirmed that the values ​​of various specimens are distributed along roughly the same curve, regardless of the gravel and stone content and particle size.

[0042] By using this relationship, even for actual ground materials containing gravel and stone, it is possible to organize them into a single resistivity-dry density relationship, i.e., a single calibration curve, regardless of the content and particle size of the gravel and stone. Therefore, in this embodiment, specifically, in a preliminary laboratory test, a test specimen is used in which the gravel and stone G have been removed from the on-site ground material S using a sieve or the like, and a predetermined relationship between the electrical resistivity and dry density of the soil portion from which the gravel and stone G have been removed from the ground material S, i.e., only a single calibration curve, is obtained.

[0043] That is, as shown in Figure 9(A), in the past, for example, for a ground material S having three different gravel and stone contents and three different gravel and stone particle sizes, a total of nine calibration curves would be required. On the other hand, in this embodiment, as shown in Figure 9(B), it is sufficient to obtain only one calibration curve.

[0044] As described above, an electrical resistance measurement step is performed on the on-site ground material S by the electrical resistance measurement unit 11 of the soil measurement device 1 to measure the resistivity of the ground material S. As described above, a soil portion dry density derivation step is performed to derive the dry density of the soil portion of the ground material S from the resistivity of the ground material S measured in the electrical resistance measurement step and the predetermined relationship between the resistivity and dry density of the soil portion from which gravel and stone have been removed from the ground material S. In other words, by applying the resistivity of the ground material S measured on-site to only one calibration curve obtained, the dry density ρ of the on-site ground material S can be calculated. ds is obtained.

[0045] Furthermore, as described above, the dry density ρ of the soil part of the ground material S derived in the soil part dry density derivation process ds and the bone-dry density ρ of the gravel and stone components of the ground material S dg The ratio of the mass of gravel and stone to the mass of the ground material S is the gravel and stone content P = m g / (m s +m g ) and the overall dry density ρ of the geomaterial S based on d The whole dry density deriving step is performed to derive the bone dry density ρ of the gravel and stone components. dg The gravel and stone content P is generally always measured at the construction site.

[0046] In the whole dry density derivation step, the whole dry density derivation unit 13 of the soil quality measuring device 1 calculates the dry density ρ of the soil part of the ground material S calculated in the soil part dry density derivation step. ds and the bone-dry density ρ of the gravel and stone content G of the ground material S dg and the gravel content P, the dry density ρ of the ground material that satisfies the following equation (3) dEquation (3) is known as the Walker-Holtz grain size correction formula (Walker and Holtz, 1951). ρ d =ρ ds ρ dg / {P·ρ ds +(1-P)·ρ dg} …(3)

[0047] As described above, according to this embodiment, the electrical resistance of the ground material S is measured in the electrical resistance measurement step. As described above, in the ground material S containing gravel and stone G, the electrical resistance of the ground material S is considered to depend only on the electrical resistance of the soil portion from which the gravel and stone G has been removed, and not on the state of the gravel and stone G. Therefore, in the soil portion dry density derivation step, the dry density of the soil portion of the ground material S is derived based on the electrical resistance of the ground material S measured in the electrical resistance measurement step and a predetermined relationship between the electrical resistance and dry density of the soil portion from which the gravel and stone G has been removed. In the overall dry density derivation step, the dry density of the ground material S is derived based on the dry density of the soil portion of the ground material S derived in the soil portion dry density derivation step, the density of the gravel and stone G of the ground material S, and the gravel and stone content, which is the ratio of the mass of the gravel and stone G to the mass of the ground material S. This eliminates the need to obtain calibration curves for each particle size and content of gravel and stone components G in ground material S during indoor testing, thereby reducing the labor required for indoor testing and improving efficiency.

[0048] In other words, when obtaining a single calibration curve through preliminary laboratory testing, even if the on-site ground material S contains gravel and stone G, the laboratory test can be performed on specimens from which the gravel and stone G has been removed using a sieve or other method. Then, at the site, it is sufficient to correct the measured resistivity of the ground material S and the dry density of the soil portion of the ground material obtained from a single calibration curve by using the density of the gravel and stone G of the ground material S, which is always known at the site, and the gravel and stone content, which is the ratio of the mass of the gravel and stone G to the mass of the ground material S. In other words, there is no need to obtain a calibration curve by changing the content and particle size of the gravel and stone G in the laboratory test. Furthermore, there is no need to perform laboratory tests on specimens of ground material S containing gravel and stone G. This reduces the labor required for laboratory testing.

[0049] According to the present embodiment, in the whole dry density derivation step, the dry density ρ of the soil part of the ground material S derived in the soil part dry density derivation step is ds and the bone-dry density ρ of the gravel and stone content G of the ground material S dg and the gravel content P, the Walker-Holtz grain size correction formula ρ d =ρ ds ρ dg / {P·ρ ds +(1-P)·ρ dg}, the total dry density ρ of the ground material S that satisfies d is derived, the overall dry density ρ of the ground material S can be calculated by simple calculation. d can be derived.

[0050] In addition, according to this embodiment, in the electrical resistance measurement process, the electrical resistance of the ground material S is measured by an electrode that moves over the ground material S and contacts the ground material S, so that the dry density of a wider range of ground material S can be derived within the same period of time.

[0051] Furthermore, according to this embodiment, gravel is soil particles contained in the ground material S with a particle size of 2 mm or more and less than 75 mm, and stone is soil particles contained in the ground material S with a particle size of 75 mm or more. Based on the knowledge of the inventors, in the ground material S containing these gravel and stone components G, the electrical resistance of the ground material S is considered to depend only on the electrical resistance of the soil portion from which these gravel and stone components G have been removed from the ground material S. Furthermore, since these gravel and stone components are both specified in the Japanese Industrial Standard (JIS A 0207), efficiency can be further improved by using a soil quality measurement method that conforms to the Japanese Industrial Standard.

[0052] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be embodied in various forms. For example, in the above embodiments, in the overall dry density derivation step, the overall dry density of the ground material S is derived using the Walker-Holtz granularity correction formula. However, the overall dry density of the ground material S may be derived from the dry density of the soil portion of the ground material S, the bone dry density of the gravel and stone components G of the ground material S, and the gravel and stone content ratios based on a relationship other than the Walker-Holtz granularity correction formula, such as a granularity correction formula that modifies the Walker-Holtz granularity correction formula.

[0053] In addition, the soil portion dry density derivation unit 12 and the overall dry density derivation unit 13 of the soil measuring device 1 may be arranged outside the soil measuring device 1, and the soil portion dry density derivation process and the overall dry density derivation process may be performed by the soil portion dry density derivation unit 12 and the overall dry density derivation unit 13 arranged outside the soil measuring device 1 based on the electrical resistance of the ground material S transmitted from the soil measuring device 1 by wireless communication via the communication unit 15.

[0054] Furthermore, the soil measurement device 1 does not necessarily have to move over the ground material S, but may be fixed on the ground material S. Furthermore, the electrical resistance of the ground material S may be measured using a probe-type electrode instead of the wheel-shaped electrode 9. Furthermore, the soil measurement method of this embodiment does not necessarily have to be performed by the soil measurement device 1, but may be performed manually. Furthermore, the soil measurement method of this embodiment may be performed regardless of whether or not the soil is compacted. [Explanation of symbols]

[0055] 1...soil quality measuring device, 4...central frame section, 5...electrode section, 6...drive wheel, 7...auxiliary wheel, 8...traction body, 9...wheel-shaped electrode, 10...ECU, 11...electrical resistance measuring section, 12...soil dry density deriving section, 13...total dry density deriving section, 14...positioning section, 15...communication section, 16...drive section, 19...electrode, 21...electrical resistance measuring device, S...ground material, G...gravel / stone content, C...current, X, Y...direction.

Claims

1. an electrical resistance measurement step of measuring the electrical resistance of the ground material; A soil portion dry density deriving step of deriving the dry density of the soil portion of the ground material based on the electrical resistance of the ground material measured in the electrical resistance measuring step and a predetermined relationship between the electrical resistance and dry density of the soil portion from which gravel and stone have been removed from the ground material; an overall dry density deriving step of deriving the dry density of the ground material based on the dry density of the soil portion of the ground material derived in the soil portion dry density deriving step, the density of the gravel and stone portions of the ground material, and the gravel and stone content, which is the ratio of the mass of the gravel and stone portions to the mass of the ground material; Equipped with In a preliminary laboratory test, a specimen in which gravel and stone have been removed from the ground material at the site is used, and a predetermined relationship between the electrical resistivity and dry density of the soil portion from which gravel and stone have been removed is obtained as a single calibration curve; The dry density of the ground material at the site is obtained by applying the resistivity of the ground material measured at the site in the electrical resistance measurement step to the calibration curve obtained alone. Soil measurement method.

2. In the whole dry density derivation step, the dry density ρ of the soil part of the ground material derived in the soil part dry density derivation step is calculated. ｄｓ and the bone dry density ρ of the gravel and stone components of the ground material ｄｇ and the gravel content P, r ｄ =ρ ｄｓ ・r ｄｇ / {P・r ｄｓ + (1-P)・p ｄｇ } The dry density ρ of the ground material satisfies ｄ The soil quality measuring method according to claim 1 , further comprising the step of:

3. 3. The soil measuring method according to claim 1, wherein the electrical resistance measuring step measures the electrical resistance of the ground material by using an electrode that moves over the ground material and comes into contact with the ground material.

4. A soil quality measurement method described in any one of claims 1 to 3, wherein the gravel component is soil particles contained in the ground material with a particle size of 2 mm or more and less than 75 mm, and the stone component is soil particles contained in the ground material with a particle size of 75 mm or more.

5. an electrical resistance measuring unit for measuring the electrical resistance of the ground material; a soil portion dry density deriving unit that derives the dry density of the soil portion of the ground material based on the electrical resistance of the ground material measured by the electrical resistance measuring unit and a predetermined relationship between the electrical resistance and dry density of the soil portion from which gravel and stone have been removed from the ground material; an overall dry density deriving unit that derives the dry density of the ground material based on the dry density of the soil portion of the ground material derived by the soil portion dry density deriving unit, the density of the gravel and stone portions of the ground material, and the gravel and stone content, which is the ratio of the mass of the gravel and stone portions to the mass of the ground material; Equipped with In a preliminary laboratory test, a specimen in which gravel and stone have been removed from the ground material at the site is used, and a predetermined relationship between the electrical resistivity and dry density of the soil portion from which gravel and stone have been removed is obtained as a single calibration curve; The electrical resistance measurement unit applies the resistivity of the ground material measured at the site to the single calibration curve obtained, thereby obtaining the dry density of the ground material at the site. Soil quality measuring device.

6. The whole dry density deriving unit calculates the dry density ρ of the soil part of the ground material derived by the soil part dry density deriving unit. ｄｓ and the bone dry density ρ of the gravel and stone components of the ground material ｄｇ and the gravel content P, r ｄ =ρ ｄｓ ・r ｄｇ / {P・P ｄｓ + (1-P)・p ｄｇ } The dry density ρ of the ground material satisfies ｄ The soil quality measuring device according to claim 5, wherein the following is derived:

7. The soil measuring device according to claim 5 or 6, wherein the electrical resistance measuring unit measures the electrical resistance of the ground material by an electrode that moves over the ground material and comes into contact with the ground material.

Images