Probe for measuring ground resistivity

Abstract

To provide a probe for measuring ground specific resistance capable of more surely measuring the specific resistance of the ground and improving durability against friction or the like.SOLUTION: This ground specific resistance measuring probe 1 has a probe body 20 having a cylinder part 201 and a columnar part 202, a push rod 30, a piston part 40 connected to the lower end of the push rod 30, and an electrode 60 fixed only to the piston part 40. When the push rod 30 is pushed downward, the piston portion 40 moves downward in the cylinder portion 201, and the tip of the electrode 60 protrudes outward from the side surface of the columnar portion 202.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a probe for measuring ground resistivity. [Background technology]

[0002] Conventionally, ground surveys have been conducted to measure electrical resistivity using boreholes excavated in the ground to determine the properties of the ground. To measure electrical resistivity, a ground resistivity measuring probe equipped with electrodes is used.

[0003] The ground resistivity measurement probe equipped with this electrode must be brought into contact with the wall of the borehole. For example, the invention described in Patent Document 1 has an outwardly protruding contact-promoting convex portion that brings the outer electrode into contact with the borehole wall. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-004473

[0005] However, when the electrode was moved inside the borehole while in contact with the wall, the protruding parts were worn away, posing a problem for the durability of the electrode.

[0006] In addition, the walls of the borehole are uneven because they are covered with soil and sand, etc. This sometimes prevents the electrodes from making contact with the wall, making it impossible to measure the resistivity of the ground. Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, the object of the present invention is to provide a probe for measuring ground resistivity that allows for more reliable measurement of ground resistivity and improves durability by allowing electrodes to protrude only when measuring ground resistivity. [Means for solving the problem]

[0008] The ground resistivity measurement probe described in claim 1 comprises a hollow rod extending in the vertical direction, a probe body connected to the lower end of the rod, a push rod that can move up and down within the hollow of the rod, a piston section connected to the lower end of the push rod, and a bendable rod-shaped electrode, a portion of which is fixed to the piston section, and is characterized in that the probe body has a cylinder section in which the piston section is housed so that it can move up and down, and a columnar section inside which an electrode guide section is formed to guide the movement of the electrode, and is configured so that when the push rod is pushed downward, the electrode of the desired length pops out from the side of the columnar section.

[0009] The ground resistivity measurement probe described in claim 2 comprises a hollow rod extending in the vertical direction, a probe body connected to the lower end of the rod, a push rod that can move up and down within the hollow of the rod, a piston section connected to the lower end of the push rod, and a bendable rod-shaped electrode with a portion fixed to the piston section, wherein the probe body has a cylinder section in which the piston section is housed so that it can move up and down, and a columnar section inside which an electrode guide section that guides the movement of the electrode is formed, and when the columnar section is divided into two in the left-right direction, the electrode guide section penetrates from the top surface of one of the halves to the side surface of the other halves, and when the piston section is located at the top of the range of its up and down movement within the cylinder section, the tip of the electrode is located in front of the side surface of the other halves.

[0010] The ground resistivity measurement probe described in claim 3 comprises a hollow rod extending in the vertical direction, a probe body connected to the lower end of the rod, a push rod that can move up and down within the hollow of the rod, a piston section connected to the lower end of the push rod, and a bendable rod-shaped electrode with a portion fixed to the piston section, wherein the probe body has a cylinder section in which the piston section is housed so that it can move up and down, and a columnar section inside which an electrode guide section that guides the movement of the electrode is formed, and when the columnar section is divided into two in the left-right direction, the electrode guide section penetrates from the top surface of one of the halves to the side surface of the other halves, and when the push rod is pushed downward, the electrode protrudes outward from the electrode guide section, and the cylinder section is provided with a regulating section that limits the movement of the piston section so that the length by which the electrode protrudes is the same as the distance by which the piston section can move up and down within the cylinder section.

[0011] The ground resistivity measurement probe described in claim 4 is a ground resistivity measurement probe described in claim 2 or 3, characterized in that the electrode guide portions are provided in multiple locations, each curved with a radius of curvature of 35 mm or more, and one end of each of the multiple electrode guide portions is arranged in a row on the side of the columnar portion in a direction diagonal to the vertical direction.

[0012] The ground resistivity measurement probe described in claim 5 is a ground resistivity measurement probe described in claim 2 or 3, characterized in that the electrode guide portions are provided in multiple locations, all curved with the same radius of curvature of 35 mm or more, and one end of each of the multiple electrode guide portions is arranged in a row on the side of the columnar portion in a diagonal direction relative to the vertical direction. [Effects of the Invention]

[0013] The ground resistivity measuring probe according to the present invention has electrodes that protrude only when measuring the ground resistivity, thereby enabling more reliable measurement of the ground resistivity and improving durability. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a front view showing an example of a ground resistivity measuring probe according to the present invention. [Figure 2] FIG. 2 is a perspective view showing an example of a probe main body. [Figure 3] FIG. 2 is a perspective view showing an example of the inside of a probe body. [Figure 4] FIG. 10 is a perspective view showing an example of the interior of a columnar portion. [Figure 5] FIG. 10 is a perspective view showing a state in which the electrodes are protruding. [Figure 6] FIG. 2 is a front view showing an example of the inside of a probe main body. [Figure 7] FIG. 2 is a perspective view showing an example of the inside of a probe body. [Figure 8] FIG. 2 is a perspective view showing an example of the inside of a probe body. [Figure 9] FIG. 2 is a perspective view showing an example of the inside of a probe body. DETAILED DESCRIPTION OF THE INVENTION

[0015] Detailed embodiments of the ground resistivity measuring probe according to the present invention will be described with reference to the drawings.

[0016] As shown in FIGS. 1 to 3 , the ground resistivity measurement probe 1 according to the present invention comprises: a plurality of hollow rods 10 detachably connected in the vertical direction (Y direction); a probe body 20 detachably connected in the vertical direction to the lower end of the lowest rod 10 among the plurality of vertically connected rods 10; a push rod 30 that penetrates the hollow interior of the rods 10 and is capable of reciprocating in the vertical direction (Y direction) within the hollow interior of the rods 10; a piston portion 40 connected to the lower end of the push rod 30; a cable 50 that passes through the hollow interior of the rod 10 so as to penetrate through the interior of the rod 10; and a bendable rod-shaped electrode 60 connected to the tip of the cable 50. The piston portion 40 is attached to the lower end of the push rod 30, and the piston portion 40 moves up and down (slides) in conjunction with the up and down movement of the push rod 30. The cable 50 is housed loosely within the hollow interior of the rod 10 along the push rod 30. The electrode 60 is fixedly attached only to the piston portion 40 and housed within the probe body 20.

[0017] The rod 10 is a hollow cylinder that extends in the vertical direction (Y direction), and multiple rods 10 can be connected in the vertical direction (Y direction). The rod 10 is open at both the top and bottom ends, allowing the push rod 30 and cable 50 to pass through the hollow interior of the cylinder.

[0018] The push rod 30 is made up of a plurality of rod-shaped bodies made of metal or resin, each having an outer diameter smaller than the hollow inner diameter of the rod 10. The push rod 30 is formed with connecting members for connecting the rod-shaped bodies to each other in the vertical direction (Y direction), and the rod-shaped bodies can be extended in the vertical direction (Y direction) via these connecting members. Furthermore, of the rod-shaped bodies extended in the vertical direction (Y direction), the lowest rod-shaped body is formed with a connecting member for connection to the piston part 40. The connection is achieved by fitting, screwing, or the like.

[0019] The piston portion 40 is made of an electrically insulating material such as polycarbonate resin, and is formed in the shape of a cube or a rectangular parallelepiped.

[0020] The push rod 30 and the piston portion 40 may be integrally formed. Alternatively, the push rod 30 and the piston portion 40 may be detachably connected. For example, as shown in Figures 8 and 9, a screw hole 40a formed in the center of the piston portion 40 is threadedly engaged with a screw portion 30a formed at the tip of the push rod 30, thereby detachably connecting the push rod 30 and the piston portion 40.

[0021] Furthermore, a plurality of through holes 40h penetrating from the upper surface to the lower surface are provided in the piston part 40 in an area excluding the vicinity of the center of the upper surface. One electrode 60 is inserted into each through hole 40h.

[0022] The cable 50 extends to the ground through the hollow of the rod 10, with one end on the ground side connected to a measuring device or a discriminator (not shown), and the other end (tip) connected to the electrode 60 via a coaxial connector or the like (not shown). It is preferable to use a coaxial cable as the cable 50.

[0023] The electrode 60 is made of a material such as piano wire or stainless steel spring wire that has high hardness (high strength) and a strong restoring force. When using piano wire for the electrode, it is desirable that the diameter be 0.7 mm or more. The electrode 60 has a predetermined length, and one end is fixedly attached near the upper part (upper surface side) of the through-hole 40h formed in the piston portion 40, and is housed within the probe body 20. The fixing method may be adhesive fixing or other general methods. Because the electrode 60 is fixedly attached to the piston portion 40, the electrode 60 moves in conjunction with the up and down movement of the piston portion 40.

[0024] The probe body 20 has a cylinder portion 201 having an internal space in which the piston portion 40 can slide up and down (Y direction), a columnar portion 202 that restricts downward movement of the piston portion 40 while allowing movement of the electrode 60, and a cone portion 203 that tapers in diameter toward the tip. The probe body 20 is made of an electrically insulating material such as polycarbonate resin or glass epoxy resin. The probe body 20 can also be made of a metal material such as stainless steel that is coated or surface-treated with an electrically insulating material. The cylinder portion 201 and the columnar portion 202 may be integrally formed, or they may be connected by screws, adhesive, or the like.

[0025] Cylinder portion 201 is open at the top, allowing piston portion 40 to be inserted from above. Cylinder portion 201 has an internal space that allows piston portion 40 to reciprocate in the up-down direction (Y direction) within cylinder portion 201. The depth within cylinder portion 201 is desirably 5 mm to 25 mm longer than the maximum distance that piston portion 40 reciprocates in the up-down direction (Y direction).

[0026] A waterproof packing 204 made of an insulating material is attached to the bottom of the cylinder portion 201. A plurality of through holes 201h are formed in the packing 204 so that the electrodes 60 can move in the vertical direction (Y direction). The diameter of the through holes 201h is preferably the same as that of the electrodes 60 or slightly smaller than the thickness of the electrodes 60 to prevent water and mud from entering the cylinder portion 201. Furthermore, the packing 204 may be provided between the cylinder portion 201 and the columnar portion 202, rather than at the bottom of the cylinder portion 201.

[0027] A plurality of electrode guide portions 205 corresponding to the number of electrodes 60 (four electrodes are used in FIG. 2 to use the four-electrode method) are formed inside the columnar portion 202. One electrode 60 can be inserted into each electrode guide portion 205, and the electrodes 60 can move freely inside the electrode guide portion 205.

[0028] 4, when columnar portion 202 is divided into two in the left-right direction (X direction) (hatching represents a cross section when divided into two), electrode guide portion 205 penetrates columnar portion 202 from top surface 202a on one side of the divided portion to side surface 202b on the other side of the divided portion. More specifically, when columnar portion 202 is divided into two along a straight line L passing through center O1 of the top surface and center O2 of the bottom surface of columnar portion 202 so that the two halves are not separated from each other, top surface-side hole 205c is provided in top surface 202a on one side of the divided columnar portion 202, and side surface-side hole 205d is provided in side surface 202b on the other side of the divided portion (the surface opposite to the cross section when divided into two), and electrode guide portion 205 penetrates columnar portion 202 from top surface-side hole 205c to side surface-side hole 205d. Electrode guide portion 205 is curved at a predetermined radius of curvature (curved portion 205b) within columnar portion 202, and the radius of curvature is preferably 35 mm or more. Also, the inner diameter of electrode guide portion 205 is preferably large enough to allow electrode 60 to move smoothly even when inserted, and to prevent soil and sand from entering.

[0029] The top surface-side holes 205c and the side surface-side holes 205d are provided in multiple numbers corresponding to the number of electrodes 60. The multiple top surface-side holes 205c are arranged in a row on the top surface 202a of one of the divided columnar portions 202. Meanwhile, the multiple side surface-side holes 205d (one end of the electrode guide portion 205) are arranged in a row at a predetermined interval along the side surface 202b of the other of the divided columnar portions 202, in a diagonal direction relative to the vertical direction (Y direction). This diagonal arrangement allows for a larger radius of curvature than when they are arranged in a row in the vertical direction (Y direction). As a result, the electrode 60 can be moved smoothly, reducing the risk of damage to the electrode 60 or the electrode guide portion 205. It is also more desirable for the curved portions 205b to all have the same radius of curvature. That is, it is more preferable that the multiple electrode guide portions 205 each have straight portions 205a of different lengths and curved portions 205b that are all curved with the same radius of curvature. This is because the smaller the radius of curvature, the more likely the electrode is to be distorted. Therefore, if even one of the multiple electrodes is distorted, the durability will be compromised. Therefore, by making all curved portions 205b have the same radius of curvature, the bending stress caused by bending acting on each electrode 60 can be equalized, thereby further improving durability. It is preferable that the side-side holes 205d are arranged in a row at an angle of 20 to 40 degrees with respect to the vertical direction (Y direction). Furthermore, the spacing between two adjacent side-side holes 205d (portions of the multiple electrode guide portions 205 located on the side of the columnar portion 202) is preferably in the range of 5 to 30 mm, more preferably 10 mm.

[0030] In this configuration, the electrode 60, one end of which is fixedly attached to the piston portion 40, passes through a through-hole formed in the packing 204, is inserted from the top surface of one of the two halves, and is guided by the electrode guide portion 205 so that the other end reaches just before the side surface of the columnar portion 202. At this time, the piston portion 40 is located at the top of its range of vertical movement within the cylinder portion 201, as shown in FIG. 3. When the push rod 30 is pressed downward, the piston portion 40 attached to the lower end of the push rod 30 moves (slides) downward within the cylinder portion 201. Then, as shown in FIG. 5, the electrode 60, which is fixedly attached to the piston portion 40, also moves downward in conjunction with the movement, and the tip of the electrode 60, which is located just before the side surface-side hole 205d (the side surface of the columnar portion 202), protrudes outward from the side surface-side hole 205d (the side surface of the columnar portion 202).

[0031] At this time, the electrode 60 needs to protrude so that its tip reaches the inner surface of the drilled hole. Therefore, a restricting member for restricting the movement of the piston 40 is provided inside the cylinder 201 so that the desired length by which the electrode 60 protrudes is the same as the distance the piston 40 can move within the internal space of the cylinder 201 (the distance between the top and bottom of the piston 40 moving up and down). For example, as shown in FIG. 6 , a threaded hole is provided through the wall of the cylinder 201, and after the piston 40 is inserted into the cylinder 201, a screw S is inserted from the outside of the wall of the cylinder 201, penetrates the wall of the cylinder 201, and the tip of the screw S protrudes from the inner wall of the cylinder 201 and is screwed in place. This allows the piston 40 to abut against the screw S, thereby limiting the movement of the piston 40 within the cylinder 201 to a predetermined range. The position of the screw hole is determined so that the range of vertical movement of the piston 40 is the same as the desired length by which the electrode 60 protrudes. 7 to 9, it is also possible to restrict the upward movement of the piston portion 40 by forming the cylinder portion 201 so that the upper side is surrounded by the inside. Alternatively, a protrusion extending radially outward may be provided on the side surface of the push rod 30, and a stopper that can come into contact with the protrusion may be provided inside the hollow of the rod 10, and the stopper may be provided protruding radially inward at a position corresponding to the desired length by which the electrode 60 is to be protruded, based on the initial position at which the push rod 30 is slid downward, so that the distance by which the push rod 30 can slide downward is the desired length by which the electrode 60 is to be protruded.

[0032] If the columnar portion 202 is hollow, the electrode guide portion 205 may be made of a flexible hose or the like. In this case, it is necessary to have a space in which the electrode 60 can be inserted, but to have a space in which the piston portion 40 cannot be inserted. For example, a stopper such as a protrusion protruding inward from the inner circumferential surface must be provided to prevent the piston portion 40 from moving downward from the top surface of the columnar portion 202, or a flexible hose or the like must be fixedly attached to the top surface of the columnar portion 202 to prevent it from slipping downward.

[0033] In this configuration, the ground resistivity measurement probe 1 according to the present invention is inserted into the borehole remaining after a screw weight penetration test (SWS test) with the cone pointing vertically downward from the ground. The plunger is slid downward at the depth at which the ground resistivity is to be measured. As the plunger slides, the electrode 60 protrudes from the probe body 20 and comes into contact with the wall of the borehole. With the electrode 60 in contact with the wall of the borehole, electricity is passed through it to measure the ground resistivity. This process is repeated at predetermined depths to determine the soil quality at each depth. [Explanation of symbols]

[0034] 1. Ground resistivity measurement probe 10 rods 20 Probe body 30 Push Stick 40 Piston section 60 electrodes 60 electrodes 201 Cylinder section 202 Columnar part 205 Electrode guide part

Claims

1. a hollow rod extending in the vertical direction; a probe body connected to the lower end of the rod; a push rod that can move up and down within the hollow of the rod; a piston portion connected to the lower end of the push rod; a bendable rod-shaped electrode, a portion of which is fixed to the piston portion; Equipped with the probe body has a cylinder portion in which the piston portion is housed so as to be movable up and down, and a columnar portion in which an electrode guide portion for guiding movement of the electrode is formed, A probe for measuring ground resistivity, characterized in that when the push rod is pushed downward, the electrode of a desired length protrudes outward from the side of the columnar portion.

2. a hollow rod extending in the vertical direction; a probe body connected to the lower end of the rod; a push rod that can move up and down within the hollow of the rod; a piston portion connected to the lower end of the push rod; a bendable rod-shaped electrode, a portion of which is fixed to the piston portion; Equipped with the probe body has a cylinder portion in which the piston portion is housed so as to be movable up and down, and a columnar portion in which an electrode guide portion for guiding movement of the electrode is formed, When the columnar portion is divided into two in the left-right direction, the electrode guide portion penetrates from an upper surface of one of the two halves to a side surface of the other halves, A probe for measuring ground resistivity, characterized in that when the piston portion is positioned at the top of the range of up and down movement within the cylinder portion, the tip of the electrode is positioned in front of the other side of the two divided parts.

3. a hollow rod extending in the vertical direction; a probe body connected to the lower end of the rod; a push rod that can move up and down within the hollow of the rod; a piston portion connected to the lower end of the push rod; a bendable rod-shaped electrode, a portion of which is fixed to the piston portion; Equipped with the probe body has a cylinder portion in which the piston portion is housed so as to be movable up and down, and a columnar portion in which an electrode guide portion for guiding movement of the electrode is formed, When the columnar portion is divided into two in the left-right direction, the electrode guide portion penetrates from an upper surface of one of the two halves to a side surface of the other halves, When the push rod is pushed downward, the electrode pops outward from the electrode guide portion. A probe for measuring ground resistivity, characterized in that the cylinder portion is provided with a regulating portion that limits the movement of the piston portion so that the length by which the electrode protrudes is the same as the distance the piston portion can move up and down within the cylinder portion.

4. The electrode guide portion is provided in plurality, and each of the electrode guide portions is curved with a curvature radius of 35 mm or more. A probe for measuring ground resistivity as described in claim 2 or 3, characterized in that one end of each of the multiple electrode guide portions is arranged in a row on the side of the columnar portion, diagonally relative to the vertical direction.

5. The electrode guide portion is provided in plurality, and all of the electrode guide portions are curved with the same curvature radius of 35 mm or more, A probe for measuring ground resistivity as described in claim 2 or 3, characterized in that one end of each of the multiple electrode guide portions is arranged in a row on the side of the columnar portion, diagonally relative to the vertical direction.

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