JP2010271130A - Soil sample holder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soil sample holder enabling the measurement of the specific resistance, thermal conductivity and elastic wave velocity of a soil sample and suitable for the measurement of the soil sample. <P>SOLUTION: The soil sample holder includes a non-conductive container 1, the thermal conductivity measuring probe 3 inserted in the soil sample, the vibrator 6 on an oscillation side coming into contact with the soil sample, the vibrator 7 on an oscillation receiving side attached toward the soil sample, a pair of current electrodes 8 and a pair of potential electrodes 9. The container 1 has an internal space 19 allowing at least the soil sample having a thickness necessary for measuring the thermal conductivity of the soil sample to be present around the thermal conductivity measuring probe 3 and also has a shape that the elastic wave propagated through the soil sample from the vibrator 6 on the oscillation side to arrive at the vibrator 7 on the oscillation receiving side arrives at the vibrator 7 on the oscillation receiving side prior to the elastic wave propagated through the wall plate of the container 1 at least in a part of a route to arrive at the vibrator 7 on the oscillation receiving side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a soil sample holder. More specifically, the present invention relates to a soil sample holder capable of measuring soil resistivity, thermal conductivity, and elastic wave velocity.

  As a sample holder used for measuring the specific resistance of a rock sample, for example, as shown in FIG. 7, there is a sample holder in which both ends of a rock sample 101 are supported by a cap 104 via a current electrode 102 and a potential electrode 103 (not shown). Patent Document 1). A copper net is used as the current electrode 102 and the potential electrode 103, and a filter paper 105 containing an electrolyte solution for ensuring conductivity is placed between the rock sample 101 and the current electrode 102, and between the current electrode 102 and the potential electrode 103. In the meantime, it is sandwiched between the potential electrode 103 and the cap 104.

Akihiko Chiba and Masahiro Kumada, “Resistivity Measurement of Granite and Tuff Samples: Influence of Resistivity of Pore Water on Rock Resistivity”, Geophysical Exploration, Vol. 47, No. 3, p. 161-172

  However, in the above sample holder, since both ends of the rock sample are sandwiched and supported by the cap 104, the soil sample cannot be used. Moreover, only specific resistance can be measured as a physical property value.

  An object of this invention is to provide the soil sample holder suitable for the measurement about a soil sample. Another object of the present invention is to provide a soil sample holder capable of measuring thermal conductivity and elastic wave velocity in addition to the specific resistance of soil.

  In order to achieve this object, a soil sample holder according to claim 1 is a non-conductive container for storing a soil sample, an insertion opening provided in a wall plate of the container, and a soil sample inserted from the insertion opening. The thermal conductivity measuring probe, the first and second vibrator mounting portions provided on the pair of opposing wall plates of the container, and the oscillation attached to the first vibrator mounting portion and in contact with the soil sample A pair of side vibrators, a vibration-receiving-side vibrator attached to the second vibrator attachment portion toward the soil sample, and a pair of wall plates that are attached to a pair of opposing wall plates of the container and allow a specific resistance measurement current to flow through the soil sample. And a pair of potential electrodes for measuring a potential difference between two locations of a soil sample in a state where a specific resistance measurement current is flowing, and the container has at least heat conductivity of the soil sample around the thermal conductivity measurement probe. Rate total The container has an internal space in which a soil sample having a thickness necessary for the presence of the elastic wave, and the container has at least an elastic wave that propagates through the soil sample from the oscillation-side vibrator and reaches the receiving-side vibrator. A part of the path has a shape that reaches the receiving-side vibrator earlier than the elastic wave that propagates through the wall plate of the container and reaches the receiving-side vibrator.

  Therefore, the soil sample is filled in the container and measurement is performed. By filling the soil sample, the current and potential electrodes are in contact with the soil sample. The measurement of the specific resistance of soil is performed by flowing a specific resistance measurement current through a soil sample using a pair of current electrodes and measuring a potential difference between the pair of potential electrodes. Moreover, the measurement of the thermal conductivity of soil is performed by using the probe for thermal conductivity measurement inserted into the soil sample from the insertion port. By filling the soil sample, there is a soil sample having a sufficient thickness for measuring the thermal conductivity around the thermal conductivity measuring probe. Therefore, it is possible to measure the thermal conductivity without the influence of the surrounding air. Furthermore, the elastic wave velocity of the soil is measured by measuring the time until the elastic wave oscillated from the oscillation-side oscillator first reaches the receiving-side oscillator. The elastic wave oscillated from the oscillator on the oscillation side is the one that propagates only the soil sample due to the shape of the container, so it reaches the receiving oscillator first. By measuring the time, the elastic wave velocity of the soil can be measured.

  In the soil sample holder according to claim 2, the oscillation-side vibrator and the receiving-side vibrator are super magnetostrictive vibrators. Therefore, a strong elastic wave can be generated, and the elastic wave that is attenuated while propagating through the soil sample can easily reach the receiving-side vibrator.

  Furthermore, in the soil sample holder according to claim 3, the vibration receiving portion of the vibration receiving side vibrator is brought into contact with the soil sample. Therefore, the elastic wave that has propagated through the soil sample can be directly received.

  In the soil sample holder of the present invention, since the soil sample is filled in the container and the measurement is performed, it is easy to measure the soil that tends to collapse. Moreover, even if soil contains water, it can be measured in a state containing water, and measurement can be performed while preventing evaporation of water. Furthermore, using one soil sample holder, the specific resistance, thermal conductivity and elastic wave velocity of the soil sample can be measured respectively. Therefore, measurement can be performed efficiently and three physical property values under the same conditions can be measured. Moreover, it is not necessary to prepare a dedicated sample holder separately for each measurement, which is convenient.

It is a longitudinal section showing a 1st embodiment of a soil sample holder of the present invention. It is sectional drawing of the soil sample holder which follows the II-II line of FIG. It is a top view of the soil sample holder. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the soil sample holder of this invention. It is a longitudinal cross-sectional view which shows 3rd Embodiment of the soil sample holder of this invention. It is a conceptual diagram of the soil sample holder for examining condition 3. It is a schematic block diagram of the conventional sample holder.

  Hereinafter, the configuration of the present invention will be described in detail based on the best mode shown in the drawings.

  1 to 3 show an example of an embodiment of a soil sample holder of the present invention. 1 and 2 show the state before putting the soil sample (the same applies to FIGS. 4 and 5). The soil sample holder includes a non-conductive container 1 for storing the soil sample, an insertion port 2 provided on the wall plate of the container 1, and a thermal conductivity measurement probe 3 inserted into the soil sample from the insertion port 2. The first and second vibrator mounting portions 4 and 5 provided on a pair of opposing wall plates of the container 1 and the oscillation-side vibrator that is attached to the first vibrator mounting portion 4 and contacts the soil sample 6, a vibration-receiving-side vibrator 7 attached to the second vibrator attachment portion 5 toward the soil sample, and a pair of opposing wall plates of the container 1, and a specific resistance measurement current is passed through the soil sample. A pair of current electrodes 8 and a pair of potential electrodes 9 for measuring a potential difference between two locations of the soil sample in a state where a specific resistance measurement current flows are provided.

  The shape of the container 1 is, for example, a rectangular parallelepiped, and has a structure in which a cover plate 11 is placed on a container body 10 including a bottom plate 10a and four side plates 10b, 10c, 10d, and 10e. The lid plate 11 is fixed to the container body 10 by using fixing means such as screws 20. However, the shape of the container 1 is not limited to a rectangular parallelepiped. In the present embodiment, the container 1 is made nonconductive by being formed of an acrylic plate. However, you may form the container 1 using nonelectroconductive board | plate materials other than an acrylic board, for example, a polypropylene board, a polyethylene board, etc. Moreover, the container 1 can be made transparent by forming the container 1 with an acrylic board, and the filled soil sample can be visually confirmed from the outside. For example, four legs 12 are attached to the container main body 10 to secure a space for placing the vibration-receiving vibrator 7.

  In the present embodiment, the insertion port 2 for inserting the thermal conductivity measurement probe 3 into the side plate (wall plate) 10 b and the first vibrator mounting portion 4 for attaching the oscillation-side vibrator 6 to the lid plate (wall plate) 11. Are provided with second vibrator attachment portions 5 for attaching the vibration-receiving-side vibrator 7 to the bottom plate (wall plate) 10a. Further, current electrodes 8 are attached to side plates (wall plates) 10c and 10d on both sides of the side plate 10b provided with the insertion port 2. That is, the cover plate 11 and the bottom plate 10a are a pair of opposing wall plates provided with the first and second vibrator mounting portions 4 and 5, and the side plate 10c and the side plate 10d are a pair of current electrodes 8 attached thereto. It is an opposing wall board. As described above, in this embodiment, the thermal conductivity measurement probe 3, the oscillation-side vibrator 6, the vibration-receiving-side vibrator 7, and the pair of current electrodes 8 and 8 are attached to separate wall plates.

  The insertion port 2 is a hole that penetrates the side plate 10b and is provided at the center of the side plate 10b. The thermal conductivity measurement probe 3 is inserted into the container 1 from the insertion port 2. For example, a rubber sleeve 13 is attached to the insertion port 2. The sleeve 13 firmly holds the thermal conductivity measurement probe 3 so that it does not wobble, and closes and seals the gap between the side plate 10b and the thermal conductivity measurement probe 3. As a measuring instrument having the probe 3 for measuring thermal conductivity, for example, a soil thermal conductivity measuring instrument (TP08) manufactured by Klimatec Co., Ltd. can be used. The thermal conductivity measuring probe 3 can be detached from the side plate 10b.

  The first vibrator mounting portion 4 is provided at the center of the upper surface of the lid plate 11. The first vibrator mounting portion 4 is provided with a hole 14 that penetrates the lid plate 11. The inner diameter of the hole 14 is substantially the same as the outer diameter of the oscillating portion 6a of the oscillation-side vibrator 6, and the hole 14 can be closed by the oscillating portion 6a. A pair of support pieces 15, 15 that sandwich the shaft portion 6 b of the oscillation-side vibrator 6 is attached to the first vibrator mounting portion 4. That is, the shaft 6 b of the oscillation-side vibrator 6 is sandwiched between the pair of support pieces 15, 15, the oscillation part 6 a is inserted into the hole 14, and the pair of support pieces 15, 15 is attached to the first vibrator attachment part 4. By attaching, the oscillation-side vibrator 6 is attached to the first vibrator attachment portion 4. The oscillation-side vibrator 6 can be detached from the first vibrator mounting portion 4.

  Each support piece 15, 15 is provided with a semicircular recess 15 a corresponding to the shape of the shaft portion 6 b, and the shaft portion 6 b is firmly sandwiched between the recesses 15 a, 15 a of the two support pieces 15, 15. . The size of the recesses 15a and 15a is such that a slight gap is generated between the two support pieces 15 and 15 with the shaft portion 6b interposed therebetween. The shaft portion 6b can be firmly clamped and held. The two support pieces 15 and 15 are coupled together by, for example, bolts 16 with the shaft portion 6b sandwiched therebetween. The two support pieces 15 and 15 joined together are fixed to the first vibrator mounting portion 4 by, for example, screws 17. The tip end surface of the oscillating portion 6a of the oscillation-side vibrator 6 is flush with the back surface of the cover plate 11, and can contact the soil sample.

  The second vibrator mounting portion 5 is provided at the center of the lower surface of the bottom plate 10a. The second vibrator mounting portion 5 is provided with a hole 18 that penetrates the bottom plate 10a. The inner diameter of the hole 18 is substantially the same as the outer diameter of the vibration receiving portion 7a of the vibration receiving side vibrator 7, and the hole 18 can be closed by the vibration receiving portion 7a. The vibration receiving side vibrator 7 is attached to the second vibrator attaching portion 5 using a pair of support pieces 15 and 15. The mounting structure of the vibration receiving side vibrator 7 is the same as the mounting structure of the oscillation side vibrator 6 described above, and the description thereof is omitted.

  In the present embodiment, the second vibrator mounting portion 5 is provided with a through hole 18 and the tip surface of the vibration receiving portion 7a of the vibration receiving side vibrator 7 inserted into the through hole 18 is flush with the inner surface of the bottom plate 10a. Thus, the vibration receiving part 7a is brought into contact with the soil sample without protruding. By bringing the vibration receiving part 7a into contact with the soil sample, the elastic wave propagating through the soil sample can be directly received.

  The oscillation-side vibrator 6 and the receiving-side vibrator 7 are giant magnetostrictive vibrators. By using the giant magnetostrictive element, it becomes easy to generate a strong elastic wave that can propagate only the soil sample and reach the receiving-side vibrator 7.

  The current electrode 8 is, for example, a plate-like electrode, and is provided over the entire inner surface of the side plates 10c and 10d. A lead wire (not shown) is connected to the current electrode 8. The lead wire is drawn out from between the container body 10 and the cover plate 11. The current electrode 8 is in contact with the soil sample. However, the position of the current electrode 8 is not limited to this, and is not particularly limited as long as it is a position where a specific resistance measurement current can be passed through the soil sample.

  The potential electrode 9 is, for example, an elongated plate-like electrode, and is provided, for example, on the inner surfaces of the side plate 10b, the bottom plate 10a, and the side plate 10e with a slight gap between the current electrode 8. A lead wire (not shown) is connected to the potential electrode 9. The lead wire is drawn out from between the container body 10 and the cover plate 11. The potential electrode 9 is in contact with the soil sample. However, the position of the potential electrode 9 is not limited to this, and is not particularly limited as long as it is a position where the potential difference between two locations of the soil sample can be measured.

  The container 1 has an internal space 19 in which at least a soil sample having a thickness necessary for measuring the thermal conductivity of the soil sample exists around the thermal conductivity measurement probe 3 (outside and in the radial direction). That is, in order to accurately measure the thermal conductivity, it is necessary that there is a soil sample in which heat is transmitted around the thermal conductivity measurement probe 3. If a soil sample having a thickness t is required around the thermal conductivity measurement probe 3, the container 1 can have a soil sample having a thickness t at least around the thermal conductivity measurement probe 3. It has an internal space 19 (condition 1). Moreover, the internal space 19 in the container 1 needs to be large enough to accommodate the thermal conductivity measurement probe 3 (condition 2).

  In the container 1, the elastic wave (P wave) that propagates from the oscillation-side vibrator 6 through the soil sample and reaches the receiving-side vibrator 7 propagates through the wall plate of the container 1 at least in part of the path. It has a shape that reaches the receiving-side vibrator 7 earlier than the elastic wave (P wave) that reaches the receiving-side vibrator 7 (condition 3). That is, in order to measure the elastic wave velocity of the soil sample, an elastic wave that has propagated through the soil sample from the oscillation-side vibrator 6 and reached the receiving-side vibrator 7 (hereinafter referred to as an elastic wave that has propagated only the soil sample). ) And an elastic wave that propagates through the wall plate of the container 1 in at least a part of the path and reaches the vibration-receiving-side vibrator 7, that is, propagates through the wall plate of the container 1 in a partial section or only the wall plate of the container 1. And the elastic wave that has reached the vibration-receiving-side vibrator 7 (hereinafter referred to as the elastic wave that has propagated through the wall plate of the container 1), and the time until the former reaches the vibration-receiving-side vibrator 7 is measured. There is a need. In order to measure the former in distinction from the latter, it is only necessary to detect the rise time of the detection signal of the receiving-side vibrator 7 by causing the former to reach the receiving-side vibrator 7 first. The velocity V1 at which the elastic wave propagates through the soil sample is slower than the velocity V2 at which the elastic wave propagates through the wall plate of the container 1 (V1 <V2). Therefore, the condition 3 cannot be satisfied simply by making the former propagation distance shorter than the latter propagation distance. The container 1 has a shape that allows the former to reach the vibration-receiving-side vibrator 7 before the latter, that is, a height H, a width W, and a depth D in consideration of the propagation speed and the propagation distance.

  The container 1 is formed so as to satisfy the above three conditions 1-3. Hereinafter, the distance between the cover plate 11 and the bottom plate 10a is H, the distance between the side plates 10c and 10d to which the current electrodes 8 are attached is the width W, and the side plate 10b to which the thermal conductivity measuring probe 3 is attached and the side plate. The container 1 satisfying the conditions 1 to 3 is examined with the distance D from the side plate 10e facing 10b as the depth D. Here, the height H, the width W, and the depth D are the dimensions inside the container 1.

First, condition 1 is examined. Since a soil sample of at least thickness t is required around the thermal conductivity measurement probe 3, if the diameter of the thermal conductivity measurement probe 3 is 2r, the height H and the width W are [t + 2r + t] = [2t + 2r. ] Must be larger than When a slight margin is α1, the height H and the width W are expressed by Equations 1 and 2.
<Equation 1> H ≧ 2t + 2r + α1
<Equation 2> W ≧ 2t + 2r + α1

Next, condition 2 will be examined. When the length of the insertion portion of the thermal conductivity measurement probe 3 into the container 1 is L4, the depth D needs to be larger than L4. Depth D is given by Equation 3 where α2 is a slight margin. However, when Condition 1 is considered, α2 ≧ t.
<Equation 3> D ≧ L4 + α2

  Next, Condition 3 will be examined based on FIG. Here, the velocity of the elastic wave propagating through the soil sample is V1, and the velocity of the elastic wave propagating through the wall plate of the container 1 is V2. Further, the oscillation-side vibrator 6 and the receiving-side vibrator 7 are provided at the center of the width W.

(1) The case where the elastic wave propagating through the wall plate of the container 1 propagates according to Snell's law. Snell's law (if total reflection holds): sinθ = V1 / V2.
The length L1 of the section a propagating through the soil sample in FIG. 6 is expressed by Equation 4 from cos θ = (W / 2) / L1.
<Equation 4> L1 = W / 2 cos θ

Further, the length L3 of the section c propagating through the soil sample is expressed by Equation 5 from L3 = L1.
<Equation 5> L3 = W / 2 cos θ

The length L2 of the section b propagating through the wall plate of the container 1 is expressed by Equation 6.
<Equation 6> L2 = H−L1sinθ × 2
= H- (W / 2cosθ) × sinθ × 2
= H-Wtanθ

Therefore, the propagation time T2 of the elastic wave propagating through the wall plate of the container 1 is expressed by Equation 7.
<Equation 7> T2 = (L1 + L3) / V1 + L2 / V2
= W / V1cosθ + (H−Wtanθ) / V2

On the other hand, the propagation time T1 of the elastic wave propagating only through the soil sample is expressed by Equation 8.
<Equation 8> T1 = H / V1

  If T1> T2, the elastic wave propagating through the wall plate of the container 1 reaches the vibration-receiving-side vibrator 7 first.

Here, when the width W when T1 = T2 is obtained, Expression 9 is obtained from H / V1 = W / V1 cos θ + (H−Wtan θ) / V2.
<Equation 9> W = H cos θ (V2−V1) / (V2−V1sin θ)

Further, by substituting Equations 10 and 11 into Equation 9 according to Snell's law, Equation 12 is obtained.
<Equation 10> sinθ = V1 / V2

In order for the elastic wave propagating only in the soil sample to reach the receiving-side vibrator 7 before the elastic wave propagating through the wall plate of the container 1, it is sufficient that the width W is larger than W in Expression 12. It becomes.

(2) When the elastic wave propagating through the wall plate of the container 1 propagates only through the wall plate The propagation time T3 of the elastic wave propagating through the wall plate of the container 1 is expressed by Equation 14.
<Equation 14> T3 = (W / 2 + H + W / 2) / V2

W when T1 = T3 is expressed by Formulas 15 and 15 from H / V1 = (W / 2 + H + W / 2) / V2.
<Equation 15> W = (V2 / V1-1) × H

In order for the elastic wave propagating only the soil sample to reach the receiving-side vibrator 7 before the elastic wave propagating through the wall plate of the container 1, it is sufficient that the width W is larger than W in the formula 15. It becomes.
<Equation 16>W> (V2 / V1-1) × H

＜数１８＞ Ｄ＞（Ｖ２／Ｖ１−１）×Ｈ
(3) When the oscillation-side vibrator 6 and the receiving-side vibrator 7 are taken as a reference, the width W and the depth D are different directions in which the container 1 is viewed, and are equivalent as elastic wave propagation paths. Therefore, when W ≦ D, Formulas 13 and 16 are adopted, and it is not necessary to consider the depth D for Condition 3. However, when W> D, W in Formulas 13 and 16 is replaced with D. Formula 17 (in the case of (1)) and Formula 18 (in the case of (2)) are adopted, and the width W does not need to be considered for the condition 3. This relationship is shown in Table 1.

<Equation 18>D> (V2 / V1-1) × H

  When the conditions 1 to 3 are summarized, the height H needs to satisfy the expression 1 of the condition 1. The width W needs to satisfy Expression 2 of Condition 1 and Expressions 13 and 16 corresponding to Condition 3. The depth D needs to satisfy Equation 3 of Condition 2 and Equations 17 and 18 corresponding to Condition 3.

  In addition, if the width W is determined in consideration of a value considered as the elastic wave velocity V1 propagating through the soil sample, the width W = depth D (or width W≈depth D) can be obtained. Then, a practical numerical value (for example, thickness t = 2 cm) considering the thickness t is applied to the height H (condition 1), and a practical numerical value (for example, considering the length L4 to the depth D (condition 2)). By applying the length L4 = 8 cm and α2 = 4 cm) and further setting the width W = depth D (or width W≈depth D), it is considered that the condition 3 is also satisfied. Therefore, considering the conditions 1 and 2, it is practical to form the container 1 so that the width W = the depth D (or the width W≈the depth D).

  When the soil sample holder is manufactured from such a viewpoint, the container 1 becomes a flat rectangular parallelepiped having a small height H compared to the width W and the depth D. For example, the height H is 5 cm, the width W is 12 cm, and the depth D is 12 cm. However, it is not limited to these values, and can be changed as long as the conditions 1, 2, and 3 are satisfied. Moreover, it is preferable to make the container 1 as small as possible from the viewpoint of reducing the filling amount of the soil sample holder.

  Next, measurement using a soil sample holder will be described.

  After the thermal conductivity measurement probe 3 and the vibration-receiving vibrator 7 are attached to the container body 10, the container body 10 is filled with a soil sample. The insertion port 2 of the side plate 10b is closed by the attachment of the thermal conductivity measurement probe 3, and the hole 18 of the bottom plate 10a is closed by the attachment of the vibration receiving side vibrator 7, so that even if the soil sample contains moisture. There is no leakage. When the soil sample is filled, the vibration receiving portion 7a of the vibration receiving side vibrator 7 comes into contact with the soil sample. In addition, a soil sample having a thickness sufficient for measurement is filled around the thermal conductivity measurement probe 3. Then, after filling the soil sample to a predetermined height, the cover plate 11 to which the oscillation-side vibrator 6 is attached is put on the container body 10 and fixed. By covering the cover plate 11, the oscillation part 6a of the oscillation-side vibrator 6 comes into contact with the soil sample.

  Next, measurement of the specific resistance of the soil sample will be described. This soil sample holder is used in a quadrupole method using two current electrodes 8 and two potential electrodes 9. The lead wire of the current electrode 8 and the lead wire of the potential electrode 9 are connected to a specific resistance measuring instrument (not shown). Then, a rectangular wave current is passed between the current electrodes 8, and the potential difference between two locations of the soil sample generated at that time is measured using the potential electrode 9. Since container 1 is non-conductive, current flows through the soil sample. As the measuring instrument, for example, a mini-ohm manufactured by Applied Geological Co., Ltd. can be used.

  Next, measurement of the elastic wave velocity of the soil sample will be described. The oscillation-side vibrator 6 is connected to a vibrator oscillation driver amplifier (not shown) (for example, a vibrator oscillation driver amplifier manufactured by Japan Underground Exploration), and the oscillation-side vibrator 6 and the receiving-side vibrator 7 are connected to an oscilloscope (not shown). To do. By oscillating an elastic wave (pulse wave) from the oscillating unit 6a of the oscillation-side vibrator 6 and receiving the elastic wave propagated through the soil sample by the vibration-receiving unit 7a of the receiving-side vibrator 7, the initial arrival of the P wave Time is measured and the P wave velocity of the soil sample is measured. The oscilloscope also reads the vibration waveform and the oscillation waveform, and measures the elastic wave velocity by reading the time difference between the oscillation time and the vibration reception time.

  Next, measurement of the thermal conductivity of the soil sample will be described. The surrounding soil sample is heated by applying a certain amount of heat to the probe 3 for measuring thermal conductivity, and the thermal conductivity is obtained from the manner of temperature rise (temperature gradient) by observing the temperature change. Moreover, the specific thermal resistance which is the reciprocal number can also be calculated | required by calculating | requiring thermal conductivity.

  Thus, three physical property values, such as specific resistance, elastic wave velocity, and thermal conductivity, can be measured using one soil sample holder. Since three physical property values can be measured continuously without refilling the soil sample, it is very efficient. Moreover, it is not necessary to individually manufacture a dedicated soil sample holder in order to measure each physical property value.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention.

  For example, in the above description, the oscillation-side vibrator 6 and the vibration-receiving-side vibrator 7 are attached to the lid plate 11 and the bottom plate 10a, the thermal conductivity measurement probe 3 is attached to the side plate 10b, and the current electrode 8 is attached to the side plate 10c and the side plate 10d. However, the present invention is not limited to this. For example, as shown in FIG. 4, the oscillation-side vibrator 6 and the vibration-receiving vibrator 7 are attached to the side plate 10d and the side plate 10c, and the thermal conductivity measurement is applied to the side plate 10b. The probe 3 may be attached, and the current electrode 8 may be attached to the cover plate 11 and the bottom plate 10a. For example, as shown in FIG. 5, the oscillation-side vibrator 6 and the vibration-side vibrator 7 are attached to the side plate 10b and the side plate 10e. 10e and the oscillation-side vibrator 7 are omitted), the thermal conductivity measuring probe 3 is attached to the lid plate 11 or the bottom plate 10a (the lid plate 11 in FIG. 5), and the current electrode 8 is attached to the side plate 10c and the side plate 10d. Also good, the other also good.

  In the above description, the vibration receiving portion 7a of the vibration receiving side vibrator 7 is brought into contact with the soil sample. However, when the elastic wave propagating only the soil sample can be received, the vibration receiving portion 7a is not necessarily used as the soil sample. It is not necessary to make it contact, and you may attach to the outer side of the baseplate 10a. In this case, it is not necessary to make holes 18 in the bottom plate 10a of the container body 10, and water leakage can be completely prevented. However, it is preferable to reduce the thickness of the bottom plate 10a at the portion where the vibration receiving portion 7a of the vibration receiving side vibrator 7 is attached to make it easier to receive the elastic wave.

  The container 1 that satisfies the conditions 1 to 3 was designed.

  As for the height H, about 2 cm is required as the thickness t. When the diameter 2r of the thermal conductivity measurement probe 3 and the margin α1 are combined to be about 1 cm, for example, the height H is 5 cm from Equation 1 in Condition 1. That's it. Since it is preferable that the height H is small from the viewpoint of reducing the filling amount of the soil sample, the height H is set to 5 cm. In condition 1, the width W is also 5 cm, which is the same as the height H (Formula 2).

  Regarding the depth D, the length L4 of the portion where the thermal conductivity measurement probe 3 is inserted into the container 1 is 8 cm, for example, and the depth D is 8 cm + α2 or more from Equation 3 in Condition 2. From the viewpoint of reducing the filling amount of the soil sample, the depth D is preferably smaller, so the depth D is set to 8 cm + α2. Further, when the width W is determined in consideration of the value considered as the elastic wave velocity V1 propagating through the soil sample, the width W can be set to the depth D, and therefore the width W is also set to 8 cm + α2.

  Next, Condition 3 will be examined. For example, when V1: 1000 m / s and V2: 2730 m / s, as described above, the height H is 5 cm (0.05 m) and W = D, so the width W is (1) In the case of 0.034 m (Formula 13) and (2), it becomes 0.087 m (Formula 16).

  That is, when the elastic wave propagates through the wall plate of the container 1 in accordance with Snell's law of (1), the width W = 0.034 m (= 3.4 cm), which is smaller than 5 cm according to Equation 2 of Condition 1. Considering condition 1, it becomes unnecessary to consider condition 3.

  In addition, when the elastic wave of (2) propagates only through the wall plate of the container 1, the width W = 0.087 m (= 8.7 cm), which is larger than 5 cm according to Equation 2 of Condition 1, 2 is almost the same as 8cm + α2 (in the case of Equation 3, W = D), it is not necessary to consider the condition 3 by appropriately setting the condition 2.

Here, when the width W in the case of (1): 5 cm and the width W in the case of (2): 8 cm + α2, since “(1) width W” <“(2) width W”, By considering the case of (2), it is not necessary to consider the case of (1). Therefore, when the width W is determined in consideration of the case of (2), it is not necessary to consider the conditions 1 and 3 by appropriately setting the condition 2 for the width W. Here, α2 in condition 2 is, for example, 4 cm, and W ≧ 12 cm (= 8 cm + 4 cm) from Equation 3 (in the case of W = D). And from the viewpoint of reducing the filling amount of the soil sample, the width W was set to 12 cm.
Moreover, since W = D, the depth D was also set to 12 cm.

  In condition 3, especially in the case of (2), the velocity V1 of the elastic wave propagating through the soil sample is slowed down, so that the elastic wave propagating only through the wall plate of the container 1 is applied to the receiving-side vibrator 7. It may be possible to reach first. However, if the soil sample is to be measured as in the present invention, α2 is set to 4 cm and the propagation path when the elastic wave propagates only through the wall plate of the container 1 is made sufficiently long. It is possible to prevent a situation in which the elastic wave propagating only through the wall plate of the container 1 reaches the receiving-side vibrator 7 earlier than the elastic wave propagating through only the sample. However, from the actual measurement data, it is presumed that the elastic wave in the case (2) does not reach the vibration receiving side vibrator 7.

  From the above, the shape of the container 1 was set to height H: 5 cm, width W: 12 cm, and depth D: 12 cm.

DESCRIPTION OF SYMBOLS 1 Container 2 Insertion port 3 Thermal conductivity measurement probe 4 1st vibrator attachment part 5 2nd vibrator attachment part 6 Oscillation side vibrator 7 Vibration receiving side vibrator 7a Vibration receiving part 8 of vibration receiving side vibrator Current electrode 9 Potential electrode 10a Bottom plate (wall plate)
10b, 10c, 10d Side plate (wall plate)
11 Cover plate (wall plate)
19 Internal space

Claims (3)

  A non-conductive container for storing a soil sample, an insertion opening provided in a wall plate of the container, a thermal conductivity measurement probe inserted into the soil sample from the insertion opening, and a pair of opposing containers First and second vibrator mounting portions provided on the wall plate, an oscillation-side vibrator that is attached to the first vibrator mounting portion and contacts the soil sample, and the second vibrator mounting A receiving-side vibrator attached to the soil sample toward the soil sample; a pair of current electrodes attached to a pair of opposing wall plates of the container; and a specific resistance measurement current flowing through the soil sample; and the specific resistance A pair of potential electrodes for measuring a potential difference between two locations of the soil sample in a state where a current for measurement flows is provided, and the container measures at least the thermal conductivity of the soil sample around the thermal conductivity measurement probe. In The container has an internal space in which the soil sample of a necessary thickness exists, and the container propagates the soil sample from the oscillation-side vibrator and reaches the receiving-side vibrator. The soil sample is characterized in that it has a shape that reaches the receiving-side vibrator earlier than an elastic wave that propagates through the wall plate of the container and reaches the receiving-side vibrator in at least a part of the path. holder.   The soil sample holder according to claim 1, wherein the oscillation-side vibrator and the receiving-side vibrator are giant magnetostrictive vibrators.   The soil sample holder according to claim 1, wherein the vibration receiving portion of the vibration receiving side vibrator is in contact with the soil sample.

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