Resistivity measurement system

Abstract

To provide a specific resistance measurement system which can efficiently perform works for measuring a ground.SOLUTION: A specific resistance measurement system 1 according to an embodiment includes: a holding body 10; a pair of potential electrodes 21 placed on a ground B while being held by the holding body 10; a pair of current electrodes 22; and a controller 30 for controlling the holding body 10, the pair of potentia electrodes 21, and the pair of current electrodes 22. The pair of potential electrodes 21 and the pair of current electrodes 22 measure the specific resistance of the ground B while facing the ground B. The control unit 30 rotates the holding body 10 on the basis of an axial line L extending to a vertical direction D2 to the holding body 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a resistivity measurement system for managing the quality of ground. [Background technology]

[0002] Japanese Patent Publication No. 3200778 describes a measurement method and device for measuring soil density and moisture content. This measurement method includes a measurement device that is a vehicle capable of traveling on the ground, a central cylinder extending vertically downward from the measurement device, and multiple external cylinders extending vertically downward from the measurement device outside the central cylinder in a plan view. Each of the central cylinder and the external cylinders is movable in the vertical direction. A drilling bit is provided at the tip of the external cylinder, and two radiation sources are attached to the outer periphery of each external cylinder. The measurement device further includes a detector and a drilling machine built into the central cylinder.

[0003] The radioisotope measurement (RI) method is described as the measurement method. In the RI method, the amount of gamma rays propagating through the soil is measured with a detector, and the density can be determined from this amount. Similarly, the moisture content of the soil can be determined by detecting the amount of neutron rays with a detector. In the measurement device described above, a hole 3 to 5 cm in diameter and 30 to 40 cm deep is drilled using a drilling machine. A central cylinder is inserted into the drilled hole, and the outer cylinder is lowered while excavating and rotating in the ground. The radiation source rotates accordingly. Furthermore, the outer cylinder is rotated and raised, and the radiation dose is detected by a detector.

[0004] Japanese Patent No. 3561816 describes a device for measuring soil density and moisture content. The device includes support legs, a level-adjustable table that can be moved up and down on the support legs, a rotating base that is rotatably supported on the level-adjustable table via a fixed base, and a measuring device attached to the rotating base. A radiation source rod containing a radiation source is provided on the bottom of the measuring device.

[0005] The measurement method using the above-mentioned measuring device involves first leveling the measurement location, excavating the ground using an excavator, and drilling a radiation source insertion hole.Then, a radiation source rod is inserted into the radiation source insertion hole, and the radiation source rod is rotated so that the measuring device begins measuring.Specifically, the measuring device detects the radiation dose from the radiation source and finishes measuring after rotating for about one minute.

[0006] Japanese Patent Publication No. 2787408 describes a measuring device for measuring the density and moisture content of ground. This measuring device is mounted in the bed of a light vehicle. The measuring device includes a measuring unit that moves up and down vertically, a boring drill that extends downward from the measuring unit, an RI radiation source attached to the tip of the boring drill, and a control unit that controls the boring drill and the RI radiation source.

[0007] The operation of the measurement device is as follows: under the control of the control unit, the measuring device penetrates into the ground and the measuring unit descends and touches the ground surface. RI is then emitted from the RI radiation source in the ground, and the measuring unit receives the emitted RI. The measuring unit measures the density and moisture content of the ground from the received RI.

[0008] JP 2019-206865 A describes a measuring device for measuring the density and moisture content of ground. The measuring device includes a shaft inserted into the ground, a circular rotating plate perpendicular to the shaft, a measuring unit disposed on the rotating plate and receiving radiation from an RI radiation source, and a radiation source rod supported by the measuring unit and having an RI radiation source.

[0009] The method for measuring ground using this measuring device involves first inserting a shaft into the ground and fixing it there. Next, a drill is lowered into the ground to create a measurement hole 30 cm deep. The radiation source rod is then lowered into the measurement hole, emitting radiation from the RI radiation source, which is then received by the measuring unit. The measuring unit then calculates the density and moisture content of the ground from the received radiation. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 3200778 [Patent Document 2] Patent No. 3561816 [Patent Document 3] Patent No. 2787408 [Patent Document 4] Japanese Patent Application Publication No. 2019-206865 Summary of the Invention [Problem to be solved by the invention]

[0011] As mentioned above, the RI method uses radiation to measure ground, and requires the insertion of a radiation source rod into the ground. This necessitates prior excavation of the ground. Excavation work can be easily performed if the ground is soft. However, if the ground is hard, it is not easy and may require a long time. Furthermore, in the case of samples that have solidified with cement, such as CSG (cemented sand and gravel), manual drilling is difficult, so holes must be drilled using a drill or other tool. Drilling often requires multiple workers. Therefore, there is room for improvement in the ease of work involved in ground measurement.

[0012] An object of the present disclosure is to provide a resistivity measurement system that can efficiently perform ground measurement work. [Means for solving the problem]

[0013] The resistivity measurement system according to the present disclosure includes (1) a holder, a pair of potential electrodes and a pair of current electrodes that are placed on the ground while being held by the holder, and a controller that controls the holder, the pair of potential electrodes, and the pair of current electrodes. The pair of potential electrodes and the pair of current electrodes measure the resistivity of the ground while facing the ground, and the controller rotates the holder around an axis that extends vertically in the holder.

[0014] In this resistivity measurement system, a holder holds a pair of potential electrodes and a pair of current electrodes. The pair of potential electrodes and the pair of current electrodes are placed on the ground. The pair of potential electrodes and the pair of current electrodes measure the resistivity of the ground while facing the ground. Therefore, the work can be easily performed by measuring the resistivity with the pair of potential electrodes and the pair of current electrodes placed on the ground without inserting a radiation source rod into the ground or excavating the ground in advance. The resistivity measurement system includes a control unit, which controls the holder, the pair of potential electrodes, and the pair of current electrodes. The control unit rotates the holder about an axis extending vertically in the holder. Therefore, the pair of potential electrodes and the pair of current electrodes measure the resistivity while rotating about the axis, allowing the resistivity measurement to be performed highly accurately and efficiently. This allows the quality of the ground to be evaluated highly accurately and efficiently.

[0015] (2) In the above (1), the resistivity measurement system may include a variable mechanism for changing the spacing between the pair of potential electrodes and the pair of current electrodes. In this case, the spacing between the pair of potential electrodes and the pair of current electrodes is changed by the variable mechanism. When resistivity is measured using a pair of potential electrodes and a pair of current electrodes, the measurement depth depends on the electrode spacing. Therefore, by changing the spacing between the pair of potential electrodes and the pair of current electrodes using the variable mechanism, it becomes possible to change the depth at which resistivity is measured in the ground. Therefore, since the depth at which resistivity is measured can be easily changed, ground quality evaluation can be performed more efficiently and with higher accuracy.

[0016] (3) In the above (1) or (2), the resistivity measurement system may include a handle connected to the holder. In this case, the holder holding the pair of potential electrodes and the pair of current electrodes can be easily carried by holding the handle. This improves the portability of the resistivity measurement system and allows resistivity measurements to be easily performed over a wide range, further improving the workability of quality evaluation.

[0017] (4) In any of the above (1) to (3), the control unit may measure the resistivity multiple times while rotating the holder and calculate the average value of the multiple resistivities. In this case, the resistivity of the ground can be measured more easily and with higher accuracy.

[0018] (5) In any of (1) to (4) above, the holder may have a plurality of electrode holders that hold the pair of potential electrodes and the pair of current electrodes facing the ground. The resistivity measurement system may include a plurality of spring mechanisms that are provided corresponding to the plurality of electrode holders and bias each electrode holder toward the ground. In this case, the electrode holders that hold the pair of potential electrodes and the pair of current electrodes facing the ground are biased toward the ground by the spring mechanisms. Therefore, the pair of potential electrodes and the pair of current electrodes are biased by the spring mechanisms so as to be pressed against the ground, so that each potential electrode and each current electrode can follow the ground even if there is unevenness. This makes it possible to measure the resistivity of the ground more easily and with higher accuracy.

[0019] (6) In any of the above (1) to (5), the resistivity measurement system may include a moisture meter that measures the moisture content of the ground, and the moisture meter may be attached to the holder. In this case, the moisture content of the ground can be measured by the moisture meter, allowing for more accurate evaluation of the quality of the ground. Furthermore, the moisture meter is attached to the holder. Therefore, the resistivity measurement system equipped with the moisture meter can be made compact and easy to carry.

[0020] (7) In the above (6), the moisture meter may be a scattering type RI moisture meter. In this case, the moisture meter can be placed on the ground to measure the moisture in the ground, making it easy to measure the moisture in the ground.

[0021] (8) In the above (6), the moisture meter may be a dielectric constant measurement unit that measures the dielectric constant of the ground, and the control unit may calculate the volumetric water content from the dielectric constant measured by the dielectric constant measurement unit. In this case, the dielectric constant is measured, and the volumetric water content of the ground is calculated from the measured dielectric constant. Therefore, the quality of the ground can be evaluated with higher accuracy. [Effects of the Invention]

[0022] According to the present disclosure, ground measurement work can be carried out efficiently. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a side view schematically showing a resistivity measurement system according to an embodiment. [Figure 2] FIG. 2 is a diagram schematically showing a pair of potential electrodes and a pair of current electrodes in the resistivity measurement system of FIG. [Figure 3] FIG. 10 is a perspective view showing a resistivity measurement system according to a modified example. [Figure 4] FIG. 4 is a plan view showing the resistivity measurement system of FIG. 3. [Figure 5] FIG. 5 is a perspective view showing the resistivity measurement system of FIG. 4 being towed. [Figure 6] 4 is a perspective view showing an electrode holding portion and a spring mechanism of the resistivity measurement system of FIG. 3. FIG. [Figure 7] 1 is a diagram schematically illustrating a resistivity measurement system including a relative dielectric constant measurement unit according to an embodiment. [Figure 8] FIG. 10 is a side view schematically showing a resistivity measurement system including a relative dielectric constant measurement unit according to a modified example. [Figure 9] FIG. 10 is a side view schematically showing a resistivity measurement system including a relative dielectric constant measurement unit according to a further modified example. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, an embodiment of a resistivity measurement system according to the present disclosure will be described with reference to the drawings. In the description of the drawings, identical or corresponding elements are designated by the same reference numerals, and duplicate explanations will be omitted as appropriate. In addition, the drawings may be partially simplified or exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those shown in the drawings.

[0025] The resistivity measurement system 1 according to this embodiment is used, for example, at a site A where a dam is being constructed. At the site A, as an example, earth and sand is transported by a dump truck, the transported earth and sand is spread and leveled by a bulldozer, and the spread and leveled earth and sand is compacted by a vibrating roller. The vibrating roller compacts the earth and sand by going back and forth multiple times at the site A, and performs rolling compaction of the embankment at the site A.

[0026] The resistivity measurement system 1 measures the resistivity of ground B (soil) at site A while moving over ground S after it has been compacted by a compaction machine such as a vibratory roller. Ground S is a construction surface formed by compaction. The resistivity measurement system 1 evaluates the quality of ground B by deriving the dry density or wet density (ground density), which is correlated with resistivity, and measures, for example, the effectiveness of compaction by the compaction machine. Ground B may be composed of, for example, CSG material or cover soil for a radioactive disposal project.

[0027] As shown in FIGS. 1 and 2, the resistivity measurement system 1 includes a holder 10 including a dielectric and four electrodes 20. The four electrodes 20 are a pair of potential electrodes 21, which are capacitor electrodes held by the holder 10, and a pair of current electrodes 22. The resistivity measurement system 1 measures the resistivity of the ground B using a four-electrode method. The holder 10 is, for example, box-shaped. The holder 10 moves, for example, above the ground S. The potential electrodes 21 and the current electrodes 22 are each located close to the ground S and measure the resistivity of the ground B.

[0028] For example, the holder 10 has an elongated shape. In the resistivity measurement system 1, the pair of current electrodes 22 are positioned closer to both ends of the pair of potential electrodes 21 in the longitudinal direction D1 of the holder 10. As an example, the pair of potential electrodes 21 and the pair of current electrodes 22 are arranged in a Wenner configuration. However, the arrangement of the potential electrodes 21 and the current electrodes 22 may be an arrangement other than the Wenner configuration.

[0029] 1 and 2, the pair of potential electrodes 21 and the pair of current electrodes 22 may be arranged in a facing configuration that forms a square shape in a plan view. In the case of this facing configuration, the arrangement of the potential electrodes 21 and the current electrodes 22 can be made more compact, which can further increase the portability of the holder 10. However, the arrangement of the potential electrodes 21 and the current electrodes 22 is not particularly limited.

[0030] The potential electrode 21 and the current electrode 22 are dragged, for example, on the ground surface S. Each of the potential electrode 21 and the current electrode 22 has a dielectric 23 facing the ground surface S and a conductor 24 electrically connected to the dielectric 23. The dielectric 23 is, for example, a plate-like member made of synthetic resin.

[0031] Since the dielectric 23 is dragged over the ground S while in contact with the ground S, it is preferable that the dielectric 23 be made of a material that can withstand contact with the ground S. The dielectric 23 includes, for example, at least one of high-density polyethylene, hard polyurethane, and ABS (Acrylonitrile Butadiene Styrene) resin.

[0032] The conductor 24 is a flat plate containing a conductive metal. The resistivity measurement system 1 further includes an AC power supply 25 and an electrometer 26. The AC power supply 25 is electrically connected to the conductor 24 of each current electrode 22. The electrometer 26 is electrically connected to the conductor 24 of each potential electrode 21.

[0033] AC power supply 25 applies an AC voltage between the pair of current electrodes 22, causing an AC current to flow through ground B. For example, when a voltage is applied to conductor 24 of a pair of current electrodes 22 that is not in contact with the ground S, charge accumulates between conductor 24 and ground B, causing current electrode 22 to become a capacitor. If AC power supply 25 switches the polarity of the voltage before current electrode 22, which has become a capacitor, is completely charged or discharged, AC current will flow continuously through ground B, which has a resistance value. Electrometer 26 measures the potential of pair of potential electrodes 21, which have become capacitors in the same way as current electrode 22.

[0034] The resistivity measurement system 1 is a portable electrical resistance measurement device. In other words, the resistivity measurement system 1 is a portable resistivity measurement device. The resistivity measurement system 1 has, for example, a handle portion 11 connected to a holder 10. For example, the handle portion 11 is provided at the center of the holder 10 in a plan view. As an example, the handle portion 11 has a rod-shaped portion 11b extending upward from the holder 10 and a grip portion 11c provided at the upper end of the rod-shaped portion 11b. The grip portion 11c has, for example, a ring shape. An operator performing quality measurement of the ground B can carry the resistivity measurement system 1 (holder 10) by gripping the grip portion 11c. Although an example of the configuration of the handle portion 11 has been described above, the configuration of the handle portion is not limited to the above example and can be modified as appropriate.

[0035] The resistivity measurement system 1 has a control unit 30 that controls the holder 10, a pair of potential electrodes 21, a pair of current electrodes 22, an AC power supply 25, and an electrometer 26. The control unit 30 calculates the density of the ground B from the potential measured by the electrometer 26, for example. In this case, the control unit 30 outputs or stores the calculated density of the ground B.

[0036] For example, the resistivity measurement system 1 includes an operation unit 31 for performing an operation to measure the quality of the ground B. As an example, the operation unit 31 is a measurement button. For example, the operation unit 31 is provided on the holder 10. However, the operation unit 31 may also be provided on the handle 11, and the location where the operation unit 31 is provided is not particularly limited.

[0037] In the resistivity measurement system 1, the resistivity of the ground B is measured by operating the operation unit 31 with the holder 10 positioned so that the pair of potential electrodes 21 and the pair of current electrodes 22 face the ground S. If the operation unit 31 is a measurement button, the resistivity of the ground B can be measured by pressing the operation unit 31.

[0038] Therefore, drilling holes in ground B, which is required for the RI method, is not necessary, and the quality of ground B can be quickly evaluated. For example, the frequency of the AC power supply 25 is 1 kHz or more and 10 kHz or less. In this case, measurement data of resistivity of 1,000 or more and 10,000 or less can be obtained per second. Therefore, a very large amount of measurement data can be obtained in a short time, and measurements can be performed quickly and with high precision.

[0039] For example, the resistivity measurement system 1 has a rotation mechanism 32 that rotates the holder 10. The rotation mechanism 32 rotates the holder 10 about an axis L that extends in the vertical direction D2 in the holder 10. As an example, the rotation mechanism 32 has a motor and a gear, and the motor of the rotation mechanism 32 is driven to rotate the holder 10 about the axis L.

[0040] The control unit 30 controls the rotation mechanism 32 to rotate the holder 10 around the axis L. As a specific example, when the operation unit 31 is operated, the control unit 30 outputs a control signal to the AC power supply 25 to measure the resistivity of the ground B, and outputs a control signal to the rotation mechanism 32 to rotate the holder 10. Then, the control unit 30 measures the resistivity multiple times while rotating the holder 10, and calculates the average value of the multiple resistivities.

[0041] The rotation time for one rotation of the holder 10 is, for example, 10 seconds. When the average value of a plurality of resistivities is calculated by rotating the holder 10 in this way, the average resistivity can be obtained, statistical processing of error values ​​can be easily performed, and variation in the measurement results can be reduced.

[0042] For example, the position of the axis L is eccentric with respect to the center of the holder 10 in a plan view. When the position of the axis L is eccentric with respect to the center of the holder 10, variations in the sensitivity of the electrodes can be more reliably smoothed out by rotation. As a result, it is possible to measure the resistivity with higher accuracy. As an example, the position of the axis L coincides with the position of one of the pair of potential electrodes 21. That is, the position of the axis L coincides with the position of the capacitor electrode that is located on the inner side (center side) in the longitudinal direction D1 among the four capacitor electrodes lined up along the longitudinal direction D1. However, the position of the axis L may coincide with, for example, the center of the holder 10 in a plan view (for example, the position of the handle portion 11), and is not limited to the above examples.

[0043] Next, we will explain the effects obtained from the resistivity measurement system 1 according to this embodiment. In the resistivity measurement system 1, a holder 10 holds a pair of potential electrodes 21 and a pair of current electrodes 22. The pair of potential electrodes 21 and the pair of current electrodes 22 are placed on the ground B. Then, while facing the ground B, the pair of potential electrodes 21 and the pair of current electrodes 22 measure the resistivity of the ground B.

[0044] Therefore, the measurement of ground B can be easily performed by measuring the resistivity with a pair of potential electrodes 21 and a pair of current electrodes 22 placed on ground B, without the need to insert a radiation source rod into the ground or excavate ground B in advance. The resistivity measurement system 1 includes a control unit 30, which controls the holder 10, the pair of potential electrodes 21, and the pair of current electrodes 22. The control unit 30 rotates the holder 10 about an axis L extending in the vertical direction D2. Therefore, the pair of potential electrodes 21 and the pair of current electrodes 22 measure the resistivity while rotating, so the resistivity measurement can be performed with high precision and efficiency. Therefore, the quality of ground B can be evaluated with high precision and efficiency.

[0045] In this embodiment, the resistivity measurement system 1 includes a handle 11 connected to the holder 10. Therefore, by holding the handle 11, the holder 10 holding the pair of potential electrodes 21 and the pair of current electrodes 22 can be easily carried. This improves the portability of the resistivity measurement system 1 and enables resistivity measurements to be easily performed over a wide range at the site A, further improving the workability of quality evaluation.

[0046] In this embodiment, the control unit 30 measures the resistivity multiple times while rotating the holder 10, and calculates the average value of the multiple resistivities. Therefore, the resistivity of the ground B can be measured more easily and with higher accuracy.

[0047] Next, a resistivity measurement system 1A according to a modified example will be described with reference to Figures 3, 4, and 5. Note that Figures 3, 4, and 5 merely show one example of the resistivity measurement system 1A. Therefore, the configuration of the resistivity measurement system is not limited to the configuration shown in Figures 3 to 5 and can be modified as appropriate. Since part of the configuration of the resistivity measurement system 1A is the same as part of the configuration of the resistivity measurement system 1 described above, the same reference numerals will be used and the same description as for the resistivity measurement system 1 will be omitted as appropriate.

[0048] 3 to 5, the resistivity measurement system 1A includes a holder 41 extending in a first direction A1 that is a direction along the ground surface S, and a second direction A2 that is a direction along the ground surface S and intersects with the first direction A1, a plurality of casters 42 that support the holder 41 so that the holder 41 can move while being spaced apart from the ground surface S, and a plurality of electrodes 20 located below the holder 41. For example, the first direction A1 is the direction in which the holder 41 moves, and the second direction A2 is a direction perpendicular to the first direction A1.

[0049] The holder 41 has a plate shape extending in the first direction A1 and the second direction A2. As an example, the holder 41 has a rectangular plate shape. The casters 42 are provided, for example, at each of the four corners of the holder 41 in a plan view. The resistivity measurement system 1A further includes a handle 44 that is gripped when lifting the holder 41.

[0050] The handle portion 44 is fixed to, for example, the upper surface 41b of the holder 41. As an example, the handle portion 44 has a pair of fixing portions 44b fixed to the upper surface 41b and a grip portion 44c connecting the upper portions of the pair of fixing portions 44b. For example, the pair of fixing portions 44b are aligned in the first direction A1, and the grip portion 44c extends in the first direction A1. The holder 41 has, for example, two handle portions 44, which are aligned in the second direction A2. Therefore, the worker can easily lift the holder 41 by holding the handle portions 44 with both hands.

[0051] For example, the multiple electrodes 20 are arranged side by side along the first direction A1 in a plan view. The resistivity measurement system 1A has, for example, two holders 41 and a linear body 48 extending in the first direction A1 between the two holders 41. The linear body 48 is, for example, detachable from the holders 41. When this linear body 48 is provided, when one of the two holders 41 is pulled in the first direction A1, one and the other of the two holders 41 can be moved in the first direction A1.

[0052] For example, two electrodes 20 are held on one of the two holders 41, and the remaining two electrodes 20 are held on the other of the two holders 41. However, the arrangement of the electrodes 20 is not limited to the above example and can be changed as appropriate. The resistivity measurement system 1A includes a variable mechanism 45 that changes the distance between the pair of potential electrodes 21 and the pair of current electrodes 22. The resistivity measurement system 1A includes, for example, a plurality of variable mechanisms 45, and each of the plurality of variable mechanisms 45 changes the distance Y between the pair of electrodes 20.

[0053] The variable mechanism 45 has, for example, a slit 45b penetrating the holder 41, a rod-shaped portion 45c inserted into the slit 45b and movable along the slit 45b, and a stopper 45d that stops the rod-shaped portion 45c above the slit 45b. Each of the multiple slits 45b extends, for example, in the first direction A1.

[0054] The potential electrode 21 and the current electrode 22 are each provided below the rod-shaped portion 45c. Therefore, the distance Y can be changed by moving the rod-shaped portion 45c along the slit 45b. The configuration of the variable mechanism is not limited to the variable mechanism 45 described above, and for example, the distance Y may be automatically changed by operating the operation unit 31 described above. Furthermore, the resistivity measurement system 1 described above may be provided with a variable mechanism that changes the distance between the pair of potential electrodes 21 and the pair of current electrodes 22.

[0055] The holder 41 includes a plurality of electrode holders 43 that hold the pair of potential electrodes 21 and the pair of current electrodes 22 facing the ground B. For example, the electrode holder 43 includes a plate-shaped portion 43c connected to the lower end of the rod-shaped portion 45c, a rod-shaped portion 43d inserted through the plate-shaped portion 43c in the vertical direction D2, and an electrode attachment portion 43f connected to the lower end of the rod-shaped portion 43d.

[0056] Fig. 6 is an enlarged perspective view of the electrode holder 43. As shown in Fig. 6, the plate-shaped portion 43c extends in the first direction A1 and the second direction A2 at the lower ends of the multiple rod-shaped portions 45c. The electrode holder 43 has multiple rod-shaped portions 43d. Each of the multiple rod-shaped portions 43d is movable in the vertical direction D2 in each of the multiple holes 43g formed in the plate-shaped portion 43c.

[0057] The electrode mounting portion 43f is connected to the lower ends of the rod-shaped portions 43d and moves in the vertical direction D2 as each rod-shaped portion 43d moves in the vertical direction D2. The electrode mounting portion 43f is, for example, frame-shaped and extends in the first direction A1 and the second direction A2, and the electrode 20 is mounted to the frame-shaped portion of the electrode mounting portion 43f. For example, the upper surface 20b and the lower surface of the electrode 20 are exposed from the electrode mounting portion 43f.

[0058] For example, the electrode attachment portion 43f has a rectangular shape extending in the first direction A1 and the second direction A2. The electrode holder 43 has, for example, a climbing portion 43h that climbs over a convex portion of the ground surface S. The climbing portion 43h has a triangular prism shape that extends in the second direction A2 at one end of the electrode attachment portion 43f in the first direction A1. By providing this climbing portion 43h, even if a convex portion of the ground surface S exists in the first direction A1, the holder 41 can climb over the convex portion.

[0059] The resistivity measurement system 1A has a plurality of spring mechanisms 46 that are provided corresponding to the plurality of electrode holders 43 and urge each electrode holder 43 toward (downward from) the ground B. The spring mechanism 46 has, for example, the aforementioned hole 43g, a rod-shaped portion 43d inserted into the hole 43g, and a spring 47 that surrounds the rod-shaped portion 43d.

[0060] One end (upper end) of the spring 47 abuts against the plate-shaped portion 43c, and the other end (lower end) of the spring 47 abuts against the electrode mounting portion 43f. The spring 47 urges the electrode mounting portion 43f toward the ground B. If the ground surface S is uneven as the holder 41 travels, the climbing portion 43h overcomes the unevenness, and the electrode mounting portion 43f and the electrode 20 come into contact with the unevenness, and the electrode mounting portion 43f and the rod-shaped portion 43d move in the vertical direction D2 relative to the plate-shaped portion 43c. At this time, because the spring 47 urges the electrode mounting portion 43f and the electrode 20 toward the ground B, even if the ground surface S is uneven, the electrode mounting portion 43f and the electrode 20 can overcome the unevenness and follow the unevenness.

[0061] As described above, the resistivity measurement system 1A, as shown in FIGS. 4 to 6, includes a variable mechanism 45 that changes the distance Y between the pair of potential electrodes 21 and the pair of current electrodes 22. Therefore, the distance Y between the pair of potential electrodes 21 and the pair of current electrodes 22 is changed by the variable mechanism 45. When resistivity is measured using the pair of potential electrodes 21 and the pair of current electrodes 22, the measurement depth depends on the distance Y between the electrodes 20. Therefore, by using the variable mechanism 45 to change the distance Y between the pair of potential electrodes 21 and the pair of current electrodes 22, it becomes possible to change the depth at which resistivity is measured in the ground B. Therefore, because the depth at which resistivity is measured can be easily changed, the quality evaluation of the ground B can be performed more efficiently and with higher accuracy.

[0062] In the resistivity measurement system 1A, the holder 41 has a plurality of electrode holders 43 that hold the pair of potential electrodes 21 and the pair of current electrodes 22 in a state where each of them faces the ground B. The resistivity measurement system 1A also has a plurality of spring mechanisms 46 that are provided corresponding to each of the plurality of electrode holders 43 and that urge each electrode holder 43 toward the ground B. Thus, the electrode holders 43 that hold the pair of potential electrodes 21 and the pair of current electrodes 22 in a state where each of them faces the ground B are urged toward the ground B by the spring mechanisms 46. Therefore, because the pair of potential electrodes 21 and the pair of current electrodes 22 are urged by the spring mechanisms 46 to be pressed against the ground B, each of the potential electrodes 21 and the current electrodes 22 can be made to follow the ground S even if the ground is uneven.

[0063] When using the electrode 20, which is a capacitor electrode, measurement is possible simply by placing the resistivity measurement system 1A on the ground S, but if there is a gap between the electrode 20 and the ground S, contact resistance may occur, which could result in a measurement error. Therefore, the resistivity measurement system 1A is structured so that a gap is less likely to occur between the ground S and the electrode 20 by providing a spring mechanism 46 in the electrode holding part 43 to which the electrode 20 is attached. Therefore, the resistivity of the ground B can be measured more easily and with higher accuracy.

[0064] Next, a resistivity measurement system 1B according to a further modified example will be described with reference to Fig. 7. In order to grasp the ground density of ground B with higher accuracy, it is desirable to measure the resistivity and moisture content of ground B. Therefore, the resistivity measurement system 1B comprises the above-mentioned holder 10, a moisture meter 51 that measures the moisture content of ground B, and a control unit 55. The moisture meter 51 is arranged next to the holder 10 that is equipped with an electrode 20 that measures the resistivity.

[0065] For example, the resistivity measurement system 1B has a first linear member 52 that connects the moisture meter 51 and the holder 10 to each other, and a second linear member 53 that extends from either the holder 10 or the moisture meter 51. In this case, the moisture meter 51 and the holder 10 can be towed over the ground S by pulling the second linear member 53. The moisture meter 51 is, for example, a relative dielectric constant measurement unit 60 that measures the relative dielectric constant of the ground B. The resistivity measurement system 1B measures the density and water content of the ground B from the resistivity measured by the electrode 20 held by the holder 10 and the relative dielectric constant measured by the relative dielectric constant measurement unit 60.

[0066] The dielectric constant measuring unit 60 is, for example, an underground radar. In this case, the dielectric constant measuring unit 60 has a transmitting unit 61 that transmits electromagnetic waves W downward to the ground B, and a receiving unit 62 that receives the electromagnetic waves W. The transmitting unit 61 irradiates the electromagnetic waves W to the layer boundary T with the construction surface K of the previous layer, and the receiving unit 62 receives the electromagnetic waves W reflected from the layer boundary T. The dielectric constant measuring unit 60 measures the time t from when the electromagnetic waves W are irradiated until the electromagnetic waves W return from the layer boundary T to the dielectric constant measuring unit 60.

[0067] The thickness C of the construction layer of the ground B is measured in advance, and the relative permittivity measurement unit 60 calculates the speed of the electromagnetic wave W from the time t and the thickness C. The thickness C may be manually input into the relative permittivity measurement unit 60, or layer thickness data measured by a GNSS (Global Navigation Satellite System) may be automatically input into the relative permittivity measurement unit 60.

[0068] There is a one-to-one relationship between the velocity of the electromagnetic wave W and the relative dielectric constant. Therefore, using this relationship, the relative dielectric constant measurement unit 60 calculates the relative dielectric constant from the velocity of the electromagnetic wave W. Then, by acquiring the relationship between the relative dielectric constant and the volumetric water content of ground B in advance through a laboratory test, the control unit 55 calculates the volumetric water content of ground B from the relative dielectric constant using this relationship. For example, the resistivity measurement system 1B estimates the density and water content of ground B from the volumetric water content and resistivity of ground B.

[0069] As described above, resistivity measurement system 1B includes moisture meter 51 that measures the moisture content of ground B, and moisture meter 51 is attached to holder 10. Therefore, moisture meter 51 can measure the moisture content of ground B, allowing for more accurate quality evaluation of ground B. Furthermore, moisture meter 51 is attached to holder 10. Therefore, resistivity measurement system 1B equipped with moisture meter 51 can be made compact and easy to carry.

[0070] As described above, the moisture meter 51 may be a relative dielectric constant measuring unit 60 that measures the relative dielectric constant of the ground B. In this case, the control unit 55 calculates the volumetric water content from the relative dielectric constant measured by the relative dielectric constant measuring unit 60. Thus, the relative dielectric constant is measured, and the volumetric content of the ground B is calculated from the measured relative dielectric constant. Therefore, the quality evaluation of the ground B can be performed with higher accuracy.

[0071] In resistivity measurement system 1B, moisture meter 51 may be a scattering-type RI moisture meter. In this case, moisture meter 51 measures the density and moisture content of ground B by irradiating radiation V downward from ground S and measuring the returned radiation V. In the case of moisture meter 51, which is a scattering-type RI moisture meter, the moisture content (volumetric moisture content) of ground B can be measured simply by placing it on ground S. In other words, since the moisture meter 51 can measure the moisture in ground B by placing it on ground S, the moisture in ground B can be measured easily and with high accuracy.

[0072] Next, a resistivity measurement system 1C according to yet another modified example will be described with reference to Fig. 8. The resistivity measurement system 1C includes a dielectric constant measurement unit 60C that has a means for measuring the dielectric constant different from that of the dielectric constant measurement unit 60. The dielectric constant measurement unit 60 measures the dielectric constant of the ground B by wide-angle measurement.

[0073] The relative permittivity measuring unit 60C has a transmitting unit 63 that transmits electromagnetic waves W, a receiving unit 64 that receives the electromagnetic waves W, and a holder 67 that movably holds the transmitting unit 63 and the receiving unit 64. The position of the transmitting unit 63 in a plan view and the position of the receiving unit 64 in a plan view are different from each other. The transmitting unit 63 and the receiving unit 64 are movable in a certain direction E on the holder 67. Here, the distance M between the transmitting unit 63 and the receiving unit 64 and the round-trip time N of the electromagnetic waves W are expressed as MN 2 Since this is a linear relationship on a plane, by finding the slope and intercept, it is possible to calculate both the propagation velocity of the electromagnetic wave W and the depth (thickness C) of the layer boundary T.

[0074] 9 shows a resistivity measurement system 1D that is a further modification of the resistivity measurement system 1C. Instead of the mobile transmitter 63 and receiver 64 of the resistivity measurement system 1C, the resistivity measurement system 1D has a plurality of transmitters 65 arranged in a fixed direction E and a plurality of receivers 66 arranged in a fixed direction E. As with the resistivity measurement system 1D described above, it is also possible to calculate both the propagation velocity of the electromagnetic wave W and the depth (thickness C) of the layer boundary T.

[0075] The above describes embodiments and various modifications of the resistivity measurement system according to the present disclosure. However, the resistivity measurement system according to the present disclosure is not limited to the above-described embodiments or modifications, and can be modified as appropriate within the scope of the gist described in the claims. In other words, the shape, size, material, number, and arrangement of each part of the resistivity measurement system are not limited to the above-described embodiments, and can be modified as appropriate.

[0076] For example, in the above-described embodiment, the resistivity measurement system 1 was described as including a rotation mechanism 32 that rotates the holder 10. However, the resistivity measurement system 1A may also be provided with a rotation mechanism that rotates the holder 41 (for example, two holders 41). In this way, the resistivity measurement system may be a combination of some of the above-described embodiments and various modified examples as appropriate.

[0077] The objects whose resistivity can be measured by the resistivity measurement system according to the present disclosure include soil, and specific examples include soil obtained at a construction site in the CSG (Cemented Sand and Gravel) method, to which cement has been added and mixed, and soil obtained in the RCD (Roller Compacted Dam-Concrete) method, in which ultra-hard concrete with a reduced amount of cement is spread and compacted with a vibrating roller or the like. [Explanation of symbols]

[0078] 1, 1A, 1B, 1C, 1D... resistivity measurement system, 10... holder, 11... handle portion, 11b... rod-shaped portion, 11c... grip portion, 20... electrode, 20b... upper surface, 21... potential electrode, 22... current electrode, 23... dielectric, 24... conductor, 25... AC power supply, 26... electrometer, 30... control unit, 31... operation unit, 32... rotation mechanism, 41... holder, 41b... upper surface, 42... caster, 43... electrode holding portion, 43c... plate-shaped portion, 43d... rod-shaped portion, 43f... electrode mounting portion, 43g... hole, 43h... climbing portion, 44... handle portion, 44b... fixed portion, 44c... grip portion, 45... variable mechanism, 45b... Slit, 45c...rod-shaped portion, 45d...stopping portion, 46...spring mechanism, 47...spring, 48...linear body, 51...moisture meter, 52...first linear body, 53...second linear body, 55...control portion, 60, 60C...dielectric constant measuring portion, 61...transmitting portion, 62...receiving portion, 63...transmitting portion, 64...receiving portion, 65...transmitting portion, 66...receiving portion, 67...holding body, A...site, A1...first direction, A2...second direction, B...ground, D1...longitudinal direction, D2...vertical direction, E...fixed direction, K...construction surface, L...axis, M...distance, N...round trip time, S...ground, T...layer boundary, t...time, V...radiation, W...electromagnetic waves, Y...spacing.

Claims

1. A holder; a pair of potential electrodes and a pair of current electrodes that are placed on the ground while being held by the holder; a control unit that controls the holder, the pair of potential electrodes, and the pair of current electrodes; Equipped with the pair of potential electrodes and the pair of current electrodes measure the resistivity of the ground while facing the ground; the control unit rotates the holder about an axis extending in a vertical direction in the holder, the holder is elongated, and the pair of current electrodes are located on both ends of the holder in the longitudinal direction relative to the pair of potential electrodes; The pair of potential electrodes and the pair of current electrodes are rotated while measuring the resistivity. Resistivity measurement system.

2. A holder; a pair of potential electrodes and a pair of current electrodes that are placed on the ground while being held by the holder; a control unit that controls the holder, the pair of potential electrodes, and the pair of current electrodes; Equipped with the pair of potential electrodes and the pair of current electrodes measure the resistivity of the ground while facing the ground; the control unit rotates the holder about an axis extending in a vertical direction in the holder, The position of the axis is eccentric with respect to the center of the holder in a plan view. Resistivity measurement system.

3. A holder; a pair of potential electrodes and a pair of current electrodes that are placed on the ground while being held by the holder; a control unit that controls the holder, the pair of potential electrodes, and the pair of current electrodes; Equipped with the pair of potential electrodes and the pair of current electrodes measure the resistivity of the ground while facing the ground; the control unit rotates the holder about an axis extending in a vertical direction in the holder, The measuring device includes an AC power source electrically connected to the conductors of each of the current electrodes, an operation unit for performing an operation to measure the quality of the ground, and a rotation mechanism for rotating the holder, When the operation unit is operated, the control unit outputs a control signal to the AC power supply to measure the resistivity of the ground, and outputs a control signal to the rotation mechanism to rotate the holder. Resistivity measurement system.

4. a variable mechanism for changing the distance between the pair of potential electrodes and the pair of current electrodes; The resistivity measurement system according to any one of claims 1 to 3.

5. A handle portion connected to the holder is provided. The resistivity measurement system according to any one of claims 1 to 3.

6. the control unit measures the resistivity a plurality of times while rotating the holder, and calculates an average value of the plurality of resistivities. The resistivity measurement system according to any one of claims 1 to 3.

7. the holder has a plurality of electrode holders that hold the pair of potential electrodes and the pair of current electrodes in a state where they are respectively facing the ground, a plurality of spring mechanisms provided corresponding to the plurality of electrode holding portions, each spring mechanism biasing the electrode holding portion toward the ground; The resistivity measurement system according to any one of claims 1 to 3.

8. a moisture meter for measuring the moisture content of the ground; The moisture meter is provided alongside the holder. The resistivity measurement system according to any one of claims 1 to 3.

9. The moisture meter is a scattering type RI moisture meter. The resistivity measurement system according to claim 8 .

10. The moisture meter is a relative dielectric constant measuring unit that measures the relative dielectric constant of the ground, the control unit calculates the volumetric water content from the relative dielectric constant measured by the relative dielectric constant measuring unit. The resistivity measurement system according to claim 8 .

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