JP5698467B2 - Measuring method, measuring apparatus and measuring program for specific heat resistance of soil - Google Patents

Description

  The present invention relates to a measurement method, a measurement apparatus, and a measurement program for the inherent thermal resistance of soil. More particularly, the present invention relates to a soil specific heat resistance measurement method, a measurement device, and a measurement program for obtaining soil specific heat resistance based on soil specific resistance that can be easily measured at a survey site. It is.

  The specific heat resistance of the soil is one of the parameters that determine the size of the transmission line embedded in the ground. Especially in the place where the embedded cables such as cable outlets of substations are concentrated, the specific heat resistance of the soil Understanding is very important. The specific thermal resistance of the soil is determined based on how the temperature of the soil heated by the heater is measured by burying a sensor such as a thermocouple and a heater in the ground, and the temperature is increased by the sensor. In general, a method of filling a micro-heater and a thermocouple in a bored hole dug in the ground is used. Although a measuring instrument that embeds a probe body with a built-in heater and thermocouple in the soil has been proposed (Japanese Patent Laid-Open No. 11-23503), it is not widely used as a commercial product and has not yet been used in general. . In addition, although what has a needle-type probe is marketed as a thermal conductivity measuring sensor (for example, Climatec Co., Ltd., CHF-TP08), it is difficult to pierce the probe into a hard ground, and at the investigation site It cannot be adopted for use.

Japanese Patent Laid-Open No. 11-23503

  However, in the above-described method of digging a boring hole and embedding a sensor and a heater, it is necessary to dig a boring hole in the ground for each measurement, and the sensor and the heater are embedded and after the measurement is completed. Since these have to be backfilled, the measurement takes time and costs increase.

  The present invention provides a method for measuring a specific heat resistance of soil, a measuring apparatus, and a program for measurement, which can be measured by a generally widespread technique and can easily determine the specific heat resistance of soil at low cost. The purpose is to provide.

  As a result of intensive studies on the relationship between physical quantities such as the specific resistance, saturation, and specific heat resistance of the soil, the present inventors have found that there is a correlation between the saturation and the specific resistance, and the saturation and the specific resistance. It was found that there is also a correlation with thermal resistance. And by further advancing research based on such knowledge, it has been found that a correlation is established between the specific resistance of soil and the specific thermal resistance, and the present invention has been completed.

  In other words, the soil specific heat resistance measuring method according to claim 1 determines in advance the relationship between the specific resistance of the soil and the specific heat resistance for each type of soil, and actually measures the specific resistance of the soil at the survey site. By applying the measurement results to the relationship where the soil types match, the specific thermal resistance at the survey site is obtained.

  In addition, the soil specific heat resistance measuring apparatus according to claim 2 is a storage means for storing the relationship between specific resistance and specific heat resistance obtained in advance for each type of soil, and the type of soil at the survey site. Input means for reading the measured value of the specific resistance of the soil at the investigation site, and calculation means for obtaining the specific thermal resistance by applying the measured value to the relationship in which the types of soil match.

  Further, the program for measuring the specific heat resistance of soil according to claim 3 is a means for reading at least the means for reading the relationship between the specific resistance and the specific heat resistance obtained for each kind of soil stored in advance in the storage means, A computer that functions as a means to read the measured soil resistivity and the newly measured resistivity value of the soil at the survey site, and to determine the specific thermal resistance by applying the measured value to the matching soil type relationship It is.

  In addition, as a result of intensive studies on the elastic wave velocity of the soil, the present inventors have found that a correlation is established between the type of soil and the S wave velocity, and to complete the present invention. It has come.

  That is, in the method for measuring the specific heat resistance of soil according to claim 4, the relationship between the specific resistance of the soil and the specific heat resistance is obtained in advance for each type of soil as the first relationship, and the type of soil and S The relationship with the wave velocity is obtained in advance for each type of geology and is used as the second relationship. The soil resistivity and the S wave velocity are actually measured at the survey site, and the measured value of the S wave velocity matches the type of geology. The soil type is estimated by applying to the second relationship, and the specific thermal resistance at the investigation site is obtained by applying the measured value of the specific resistance to the first relationship that matches the estimated soil type.

  Moreover, the soil specific heat resistance measuring apparatus according to claim 5 is the first relationship between the specific resistance and the specific heat resistance determined in advance for each type of soil and the type of soil determined in advance for each type of geology. The storage means storing the second relationship between the S wave velocity and the S wave velocity, the type of geology at the survey site, the measured value of the S wave velocity of the soil at the survey site, and the measured value of the specific resistance of the soil at the survey site The input means and the measured value of the S wave velocity are applied to the second relationship in which the geological type matches, and the soil type is estimated, and the specific resistance is measured in the first relationship that matches the estimated soil type. And calculating means for obtaining the specific thermal resistance.

  Furthermore, the soil specific heat resistance measurement program according to claim 6 is at least a first relationship which is a relationship between the specific resistance and the specific heat resistance obtained for each kind of soil stored in advance in the storage means. And means for reading the second relationship which is the relationship between the soil type and the S wave velocity obtained in advance for each type of geology, the geological type of the survey site, and the S wave velocity of the soil newly measured at the survey site Means for reading the measured value of the soil and the measured value of the specific resistance of the soil newly measured at the survey site, and applying the measured value of the S wave velocity to the second relation in which the geological type matches, estimating the type of soil The computer is caused to function as means for obtaining the specific thermal resistance by applying the measured value of the specific resistance of the soil to the first relation that matches the estimated kind of soil.

  According to the soil specific heat resistance measurement method according to claim 1, the soil specific heat resistance measurement device according to claim 2, and the soil specific heat resistance measurement program according to claim 3, the specific resistance at the survey site is measured. By doing so, the specific heat resistance of the soil can be obtained. Since the specific resistance is measured by inserting a plurality of electrodes into the ground, there is no troublesome work of digging back a borehole and refilling it, and the measurement is performed with a simple work. In addition, since the specific resistance can be measured simply by passing a current between the electrodes inserted into the ground and measuring the potential difference between the electrodes, it can be measured quickly. Furthermore, the measurement of specific resistance is widely and generally prevalent, and it is easy to obtain a measuring instrument. For these reasons, the inherent thermal resistance of the soil can be obtained at low cost by using a widely spread method.

  According to the soil specific heat resistance measurement method according to claim 4, the soil specific heat resistance measurement device according to claim 5, and the soil specific heat resistance measurement program according to claim 6, in addition to the above effects, As a result, it is possible to measure the inherent thermal resistance of the soil without examining the type of soil without drilling the borehole at the survey site.

It is a block diagram which shows 1st Embodiment of the specific heat resistance measuring apparatus of the soil of this invention. It is a flowchart which shows 1st Embodiment of the measuring method of the thermal resistance of the soil of this invention. It is a figure which shows the relationship between the specific resistance of soil, and intrinsic heat resistance. The sample holder used for experiment is shown, (A) is sectional drawing which follows the AA line (horizontal plane) of (B), (B) is sectional drawing which follows the BB line (vertical surface) of (A). is there. It is a figure which shows the relationship between saturation and specific resistance. It is a figure which shows the relationship between saturation and intrinsic heat resistance. It is a block diagram which shows 2nd Embodiment of the specific heat resistance measuring apparatus of the soil of this invention. It is a flowchart which shows 2nd Embodiment of the measuring method of the thermal resistance of the soil of this invention. It is a figure which shows the relationship between S wave velocity and 50% particle size. It is a figure which shows the relationship between S wave velocity and a porosity. It is a figure which shows the relationship between P wave velocity and S wave velocity.

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

  First, a first embodiment of the soil specific heat resistance measuring apparatus of the present invention will be described. FIG. 1 shows a soil specific heat resistance measuring apparatus according to the present invention. A soil specific heat resistance measuring device (hereinafter simply referred to as a heat resistance measuring device) includes a storage means 2 for storing a relationship 1 between a specific resistance and a specific heat resistance obtained in advance for each type of soil, and a survey site. The input means 3 for reading the soil type and the measured resistivity value of the soil at the survey site, and the calculating means 4 for obtaining the specific thermal resistance by applying the measured value to the relation 1 in which the soil type matches. is there. This thermal resistance measuring device can also be realized by executing the soil specific thermal resistance measuring program 5 of the present invention on a computer. In the present embodiment, a case where a soil specific thermal resistance measurement program (hereinafter simply referred to as a measurement program) 5 is executed on a computer will be described as an example.

  FIG. 1 shows the overall configuration of a thermal resistance measurement apparatus according to this embodiment for executing the thermal resistance measurement program 5 for soil. This thermal resistance measuring device includes a control unit 6, a storage unit (storage unit) 2, an input unit (input unit) 3, and a display unit 7, and is connected to each other by a signal line 12 such as a bus.

  The control unit 6 performs a calculation related to the control of the entire thermal resistance measurement device and the calculation of the specific thermal resistance by the measurement program 5 stored in the storage unit 2, and is, for example, a CPU (Central Processing Unit). . The storage unit 2 is a device capable of storing at least data and programs, and is, for example, a hard disk.

  The input unit 3 is an interface for giving at least an operator command or the like to the control unit 6 or the like, and is, for example, a keyboard. The display unit 7 draws and displays characters and graphics under the control of the control unit 6, and is a display, for example.

  The control unit 6 of the thermal resistance measuring device includes a relation 1 between the specific resistance and the specific thermal resistance obtained for each kind of soil stored in the storage means 2 in advance by executing the measurement program 5. The relationship reading unit 8 as a means for reading, the measurement data reading unit 9 as a means for reading the soil type at the survey site and the measured value of the specific resistance of the soil newly measured at the survey site, A calculation unit (calculation unit) 4 is configured as a unit for obtaining the specific thermal resistance by applying the matching relation 1.

  A receiving device 10 is connected to the thermal resistance measuring device by a signal line such as a bus. For example, a measured value of specific resistance newly measured at a survey site is transmitted to the thermal resistance measuring device via the receiving device 10. Supplied and stored in the storage unit 2. Here, for example, the resistivity measuring instrument 11 installed at the investigation site and the receiving device 10 may be connected by the communication line 13 so that the measured value of the resistivity measuring instrument 11 is automatically supplied to the receiving device 10. Then, the measurement value of the specific resistance measuring instrument 11 may be supplied to the receiving device 10 by an operator's transmission operation. Alternatively, the operator may directly input the measurement value of the specific resistance measuring instrument 11 by operating the input unit 3 and store it in the storage unit 2.

  The type of soil at the survey site is directly input by, for example, the operator operating the input unit 3 and stored in the storage unit 2. The soil type can be identified at the survey site.

  The relationship 1 between the specific resistance and the specific thermal resistance is obtained by conducting an experiment, for example, and is stored in the storage unit 2 in advance. The operator obtains a relationship 1 between the specific resistance and the specific heat resistance at least for the same kind of soil as the soil at the survey site. FIG. 3 shows the relationship 1 between the specific resistance and the specific thermal resistance. In this embodiment, the relationship 1 of specific resistance and specific heat resistance is calculated | required about the kind of soil, for example, Toyoura sand (standard sand), quartz sand No. 5, quartz sand No. 3, silt, clay. The empirical formula of this relation 1 is shown in Formula 1, and the constants a and n of each empirical formula are shown in Table 1, respectively. Here, g is a specific thermal resistance, ρ is a specific resistance, and a and n are constants based on soil.

<Equation 1> g = aρ ⁿ

  Next, the soil specific heat resistance measurement method of the present invention will be described. In this soil specific heat resistance measurement method (hereinafter simply referred to as heat resistance measurement method), for example, as shown in FIG. 2, relationship 1 between specific resistance and specific heat resistance is obtained in advance for each soil type (step S21), the specific resistance of the soil is actually measured at the survey site (step S22), and the measurement result is applied to the relation 1 where the soil types match to determine the specific thermal resistance at the survey site (step S23). .

  First, an experiment is performed in advance to obtain the relationship 1 between the specific resistance and the specific thermal resistance for each soil and store it in the storage unit 2 (step S21). In the present embodiment, a graph (FIG. 3) is created with the horizontal axis representing the specific resistance (Ωm) and the vertical axis representing the specific thermal resistance (° C. cm / W) based on the experimental results. An empirical formula that is relationship 1 with the intrinsic thermal resistance is obtained, and this empirical formula and its constant are stored in the storage unit 2. For example, the operator inputs the relation 1 using the input unit 3 and stores it in the storage unit 2. In FIG. 3, the solid line indicates a power approximation formula for each soil.

  Next, the measurement data reading part 9 of the control part 6 reads the measured value of the specific resistance newly measured in the investigation field, and the kind of soil from the memory | storage part 2 (step S22). Here, when the measured value of specific resistance and the kind of soil are already stored in the storage unit 2, the measurement data reading unit 9 immediately executes step S22. On the other hand, when the measured value of the specific resistance and the type of soil are not stored in the storage unit 2, the process waits for input, and after both the measured value of the specific resistance and the type of soil are stored in the storage unit 2, the step is started. S22 is executed. Then, the measurement data reading unit 9 supplies the read measurement value and soil type to the calculation unit 4.

  The calculation unit 4 reads the relationship 1 with the same soil type from the storage unit 2, applies the measurement value supplied from the measurement data reading unit 9 to the relationship 1, and obtains the specific thermal resistance (step S23). Specifically, the specific thermal resistance g is calculated by reading the constants a and n with the same soil type from the storage unit 2 and substituting the measured values of the constants a and n and the specific resistance ρ into Equation 1.

  And the calculated intrinsic thermal resistance g is memorize | stored in the memory | storage part 2, and is displayed on the display part 7 (step S24). Thereafter, the measurement program 5 ends.

  In the second and subsequent measurements, since the relationship 1 between the specific resistance and the specific thermal resistance is already stored in the storage unit 2, the process is executed from step S22 by skipping step S21.

  The present invention is, for example, a place where buried cables such as cable outlets of substations are densely packed, a route from a substation to a substation that requires high power, a route from a substation to a customer, a sewer pipe, etc. It is used to measure the specific heat resistance of soil in the section where a buried object that generates heat is nearby.

  In this invention, since the specific heat resistance of the soil can be calculated | required by measuring the specific resistance of the soil of an investigation field, the specific heat resistance of the soil can be calculated | required quickly by a simple operation | work. Therefore, the specific heat resistance of the soil can be obtained at low cost. In addition, the specific resistance measuring instrument 11 is widely and generally widespread, and is easily available. Therefore, it is possible to determine the inherent thermal resistance of the soil by using devices that are generally widely used.

  Next, a second embodiment of the soil specific heat resistance measuring apparatus of the present invention will be described. In addition, the same code | symbol is attached | subjected to the member and component same as the above-mentioned embodiment. FIG. 7 shows a soil specific heat resistance measuring apparatus (heat resistance measuring apparatus) according to the present invention. The thermal resistance measuring device includes a relationship (first relationship) 1 between the specific resistance and the specific thermal resistance obtained in advance for each soil type, and the soil type and the S wave velocity obtained in advance for each geological type. Storage means 2 storing relation (second relation) 31 and input for reading the geological type of the survey site, the measured value of S wave velocity of the soil at the survey site, and the measured value of the specific resistance of the soil at the survey site The measurement value of the S wave velocity is applied to the second relation 31 in which the geological type is matched with the means 3, and the soil type is estimated, and the specific relation in the first relation 1 that matches the estimated soil type is estimated. The calculation means 4 which calculates | requires a measured value and calculates | requires intrinsic | native thermal resistance is provided. This thermal resistance measuring device can also be realized by executing the soil specific thermal resistance measuring program 5 of the present invention on a computer. In the present embodiment, a case where a soil specific thermal resistance measurement program (hereinafter simply referred to as a measurement program) 5 is executed on a computer will be described as an example.

  FIG. 7 shows the overall configuration of the thermal resistance measurement apparatus according to the present embodiment for executing the thermal resistance measurement program 5 for soil. This thermal resistance measuring device includes a control unit 6, a storage unit (storage unit) 2, an input unit (input unit) 3, and a display unit 7, and is connected to each other by a signal line 12 such as a bus.

  The control unit 6 performs a calculation related to the control of the entire thermal resistance measurement device and the calculation of the specific thermal resistance by the measurement program 5 stored in the storage unit 2, and is, for example, a CPU (Central Processing Unit). . The storage unit 2 is a device capable of storing at least data and programs, and is, for example, a hard disk.

  The input unit 3 is an interface for giving at least an operator command or the like to the control unit 6 or the like, and is, for example, a keyboard. The display unit 7 draws and displays characters and graphics under the control of the control unit 6, and is a display, for example.

  The control unit 6 of the thermal resistance measuring device has a relationship between the specific resistance and the specific thermal resistance obtained for each kind of soil stored in advance in the storage means 2 by executing the measurement program 5. 1. Relation reading unit 8 as means for reading the second relation 31 which is the relation between the soil type and the S wave velocity obtained in advance for each relation 1 and each kind of geology, the type of geology and the investigation site The measurement data reading unit 9 as a means for reading the measured value of the S wave velocity of the soil newly measured and the measured value of the specific resistance of the soil newly measured at the investigation site, the measured value of the S wave velocity Means for obtaining the specific thermal resistance by applying the measured value of the specific resistance of the soil to the first relation 1 that matches the estimated soil type while estimating the soil type by applying to the second relation 31 having the same type As a calculation (Calculating means) 4 is formed.

  A receiver 10 is connected to the thermal resistance measuring device by a signal line such as a bus. For example, the measured value of the specific resistance of the soil and the measured value of the S wave velocity newly measured at the survey site are the received device. 10 is supplied to the thermal resistance measurement device via 10 and stored in the storage unit 2. Here, for example, the specific resistance measuring instrument 11 and the elastic wave exploration measuring instrument 32 installed at the investigation site are connected to the receiving device 10 by the communication line 13, and the measured value of the specific resistance measuring instrument 11 and the elastic wave exploration measuring instrument are connected. The measurement value of the S wave velocity by 32 (hereinafter simply referred to as the measurement value of the elastic wave exploration measuring instrument 32) may be automatically supplied to the receiving device 10, or the specific resistance measurement is performed by the transmission operation of the operator. The measurement value of the instrument 11 and the measurement value of the elastic wave exploration measuring instrument 32 may be supplied to the receiving device 10. Alternatively, the operator may directly input the measurement value of the specific resistance measuring instrument 11 and the measurement value of the elastic wave exploration measuring instrument 32 by operating the input unit 3 and store them in the storage unit 2.

  Here, as the elastic wave, there is a P wave in addition to the S wave. The reason why the S wave is used in the present embodiment is as follows. That is, the P wave velocity strongly depends on the moisture content (moisture content) contained in the soil, and when it becomes slightly unsaturated (air enters), it becomes a value close to the sound velocity (340 m / s) regardless of the type of soil. Therefore, it is not suitable for discrimination of soil type. In particular, there are many cases where the specific heat resistance of the soil at the survey site is the unsaturated ground above the groundwater surface, and the P wave is not suitable for determining the soil type. However, in the case where soil saturated with water is used as a target, use of P waves is also possible.

  In contrast, the S wave velocity is less dependent on the moisture content of the soil and depends on the particle size and porosity of the soil. FIG. 9 shows the relationship between the S wave velocity propagating through the soil and the soil particle size (50% particle size (mm)). It is the result of having experimented about a dry state and a saturation 20% state. As is clear from FIG. 9, the S wave velocity depends on the particle size of the soil, and this tendency is not significantly different between the dry state and the saturation 20% state. FIG. 10 shows the relationship between the S wave velocity propagating through the soil and the porosity (%) of the soil. It is the result of having experimented about a dry state and a saturation 20% state. As is apparent from FIG. 10, the S wave velocity depends on the porosity of the soil, and this tendency is not significantly different between the dry state and the saturation 20% state.

  From the above, it is possible to determine the type of soil based on the S wave velocity. That is, even if the porosity and particle size of the soil are the same type of soil (for example, viscous soil, sandy soil, gravel soil, etc.), the geology to which the soil belongs (for example, Yurakucho Formation, No. 7 Formation, Tokyo Formation, Edogawa) Layer, Kazusa layer, etc.) will vary, but the soil porosity and particle size relationship will not change even if the geology is different. For example, the Kanto Plain is composed of the Yurakucho Formation, the No. 7 Formation, the Tokyo Formation, the Edogawa Formation, and the Kazusa Formation. The Yurakucho Formation → the No. 7 Formation → the Tokyo Formation → the Edogawa Formation → the Kazusa Formation are older and tightened. It has become a stratum. And the porosity and particle size of soil (viscous soil, sandy soil, gravel soil) vary depending on the geology (Yurakucho Formation, No. 7 Formation, Tokyo Formation, Edogawa Formation, Kazusa Formation). The size relationship (viscous soil <sandy soil <gravelly soil) does not change even if the geology is different. The S wave velocity depends on the porosity and particle size of the soil. Therefore, the S-wave velocity of the soil changes even if the soil is the same type, if the geology is different, but the magnitude relationship of the S-wave velocity (viscous soil <sandy soil <gravelly soil) does not change even if the geology is different. . Therefore, if the relationship between the soil type and S wave velocity (second relationship 31) is obtained in advance for each quality, the type of soil is known, and the type of soil is determined by knowing the S wave velocity. be able to. The present embodiment uses this principle to estimate the soil type at the survey site.

  The type of geology at the survey site is directly input by, for example, the operator operating the input unit 3 and stored in the storage unit 2.

  The first relationship 1 that is the relationship between the specific resistance and the specific thermal resistance is obtained by conducting an experiment, for example, and is stored in the storage unit 2 in advance. The operator obtains the first relationship 1 between the specific resistance and the specific heat resistance for at least the same kind of soil as that constituting the geology of the survey site. A first relationship 1 between the specific resistance and the specific thermal resistance is shown in FIG. In the present embodiment, the first relation 1 between the specific resistance and the specific thermal resistance is obtained for, for example, Toyoura sand (standard sand), silica sand No. 5, silica sand No. 3, silt, and clay as the types of soil. Further, the empirical formula of the first relation 1 is shown in Formula 2, and the constants a and n of each empirical formula are shown in Table 2, respectively. Here, g is a specific thermal resistance, ρ is a specific resistance, and a and n are constants based on soil.

<Equation 2> g = aρ ⁿ

  The second relationship 31 that is the relationship between the type of soil and the S wave velocity is obtained, for example, through an experiment and is stored in the storage unit 2 in advance. The operator obtains the second relationship 31 between the soil type and the S wave velocity for at least the same geology as the survey site.

  Here, the relationship between the kind of soil and the S wave velocity is shown in FIG. FIG. 11 and Table 3 show the relationship between the P wave velocity and the S wave velocity for each type of soil constituting the geology. From these, it can be seen that there is a correlation between the soil type and the S wave velocity. . For example, in the Yurakucho layer, the S wave velocity (m / S) is: viscous soil: 135, sandy soil: 190, gravelly soil: 308. These values are compared with the measured values of the S wave velocity at the survey site, and the same or the closest one in the allowable range is estimated as the soil at the survey site.

  11 and Table 3 are all experiments conducted on saturated ground below the groundwater surface. In this case, the P wave velocity is between the soil types as well as the S wave velocity. There is a correlation.

  Next, a method for measuring the specific thermal resistance of soil will be described. In this thermal resistance measurement method, for example, as shown in FIG. 8, the relationship between the specific resistance of soil and the specific thermal resistance is obtained in advance for each type of soil to be the first relationship 1, and the type of soil and the S wave The relationship with the velocity is obtained in advance for each type of geology to obtain the second relationship 31 (step S41), and the soil resistivity and S wave velocity are actually measured at the survey site (step S42), and the S wave velocity is measured. The value is applied to the second relation 31 having the same geological type to estimate the type of soil, and the measured value of the specific resistance is applied to the first relation 1 matching the estimated type of soil to determine the peculiarity of the survey site The thermal resistance is obtained (step S43).

  First, an experiment is performed in advance to obtain the first relationship 1 between the specific resistance and the specific thermal resistance for each soil, and is stored in the storage unit 2. Similarly, an experiment is performed in advance to obtain the second relationship 31 between the soil type and the S wave velocity for each geological type, and the result is stored in the storage unit 2 (step S41).

  Next, the measurement data reading unit 9 of the control unit 6 reads, from the storage unit 2, the measured value of resistivity, the measured value of S wave velocity, and the type of geology at the survey site newly measured at the survey site (step S42). ). Here, when the measured value of resistivity, the measured value of S wave velocity, and the type of geology are already stored in the storage unit 2, the measurement data reading unit 9 immediately executes Step S <b> 42. On the other hand, when the measured value of specific resistance, the measured value of S wave velocity, and the type of geology are not stored in the storage unit 2, it enters a state of waiting for input, and the measured value of specific resistance, the measured value of S wave velocity, and the geological feature. Step S42 is executed after all the types are stored in the storage unit 2. Then, the measurement data reading unit 9 supplies the read measurement values and geological types to the calculation unit 4.

  The calculation unit 4 reads the second relation 31 having the same geological type from the storage unit 2, applies the measured value of the S wave velocity supplied from the measurement data reading unit 9 to the second relation 31, and the type of soil. And the first relationship 1 of the soil type that matches the estimated soil type is read from the storage unit 2, and the measured value of the specific resistance supplied from the measurement data reading unit 9 is changed to the first relationship 1. The specific thermal resistance is obtained by applying (Step S43). Specifically, the specific thermal resistance g is calculated by reading the constants a and n having the same soil type from the storage unit 2 and substituting the measured values of the constants a and n and the specific resistance ρ into Equation 2.

  The calculated intrinsic thermal resistance g is stored in the storage unit 2 and displayed on the display unit 7 (step S44). Thereafter, the measurement program 5 ends.

  In the second and subsequent measurements, since the first relationship 1 between the specific resistance and the specific thermal resistance and the second relationship 31 between the soil type and the S wave velocity are already stored in the storage unit 2, the step S41 is skipped and the process is executed from step S42.

  In the present invention, since the specific heat resistance of the soil can be obtained by measuring the specific resistance and S wave velocity of the soil at the investigation site, the specific heat resistance of the soil can be obtained quickly with a simple operation. Therefore, the specific heat resistance of the soil can be obtained at low cost. In addition, the specific resistance measuring instrument 11 and the elastic wave exploration measuring instrument 32 are widely spread and generally available. Therefore, it is possible to determine the inherent thermal resistance of the soil by using devices that are generally widely used.

  Moreover, in this embodiment, since the kind of soil can be estimated based on the 2nd relationship 31, it is peculiar of soil even if an operator does not dig a boring hole and does not investigate the kind of soil in an investigation site. Thermal resistance can be measured.

  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.

Laboratory tests were conducted to investigate the correlation among specific resistance, saturation, and specific thermal resistance as physical properties of soil. The following five types of artificial soil samples were used as soil samples.
・ Toyoura standard sand (average particle size: about 0.2mm)
・ No. 5 silica sand (average particle size: about 0.5mm)
・ No.3 silica sand (average particle size: about 1.2mm)
・ Silt (average particle size: about 0.01 mm)
-Kibushi clay (average particle size: about 0.001mm)

  The test was performed by placing an artificial soil sample in a sample holder. The sample holder used for the test is shown in FIG. The sample holder is, for example, an acrylic plate assembled in a box shape, and the dimensions are, for example, length: 12 cm, width: 12 cm, and height: 5 cm.

  A pair of left and right current electrodes 14a and 14b and a pair of left and right potential electrodes 15a and 15b for measuring the specific resistance are attached to the sample holder. A hole 18 for inserting a thermal resistance measurement probe is provided on the side surface of the sample holder in order to measure the thermal resistance.

  The specific resistance is measured as follows. A pair of left and right current electrodes 14a and 14b are attached to both side surfaces of the sample holder. A pair of left and right potential electrodes 15a and 15b are attached in the vicinity of both sides of the bottom plate. The specific resistance of the soil sample is measured by passing a rectangular wave current between the current electrodes 14a and 14b and measuring the potential difference generated at that time using the potential electrodes 15a and 15b. For the measurement, for example, a mini-ohm manufactured by Applied Geological Co., Ltd. can be used.

  The specific thermal resistance is measured as follows. A probe for thermal resistance measurement is inserted from a probe insertion hole 18 provided on the side surface of the sample holder, a sample is heated by applying a certain amount of heat to the probe, and the temperature change is observed by observing the temperature change. The specific thermal resistance of the sample is obtained from the way (temperature gradient). For the measurement, it is possible to use a soil thermal conductivity measuring device (TP08) manufactured by Klimatec Co., Ltd.

(Measurement of sample holder weight)
The weight m _h0 (unit: g) of the sample holder itself was measured. At this time, nothing was put in the sample holder, and the thermal resistance measurement probe was attached.

(Dry sample preparation)
(1) A procedure for preparing a dry sample will be described. First, a dry sample is put in a sample holder. From the viewpoint of measuring the porosity, etc., the sample should be filled up to the sample holder.

  The sample was made while compacting so that there was no gap or void. Therefore, the sample was placed in a sample holder by about 1 to 1.5 cm and sufficiently filled with a lead weight and a metal spatula. This filling operation is repeated 4 to 5 times, and after filling the sample to a slightly larger amount than the sample holder, the upper end of the sample holder and the thickness of the sample are 5 cm. The top surface of the sample was adjusted to be flat with a spatula.

(2) Next, the weight m _h (unit: g) in the state of (1) was measured. Then, using the obtained value, the porosity φ of the sample was calculated using Equation 3. Here, V is the volume of the sample holder (unit: cm ³ ), and ρ _s is the density of the soil particles (unit: g / cm ³ ).

(Making water-containing sample)
(1) The preparation of a moisture-containing sample will be described. First, a sample slightly larger than the amount that can sufficiently fill the sample holder was put in a bowl in which the dry weight had been measured in advance. The weight of the sample was measured along with the bowl, and the weight of the sample minus the weight of the bowl was recorded. A fixed amount of _mw (unit: g) of distilled water was added to the sample. The amount of water added to the sample was added in such an amount that the set saturation level was reached according to the size of the porosity, and the weight was recorded.

(2) Next, the sample and distilled water were mixed in a bowl so as to be uniform. Here, the weight of the mixed sample was measured again and recorded.

(3) Then, the mixed sample was put in the sample holder. As with the dried sample, about 1 to 1.5 cm was put and sufficiently filled with a lead weight and a metal spatula. The workability of this pressure filling operation varied greatly depending on the moisture content of the sample. Therefore, the thickness and the number of times were adjusted as necessary, and the process was repeated about 4 to 5 times. After filling the sample to a slightly larger amount than the sample holder, the upper end of the sample holder and the thickness of the sample were adjusted with a plastic spatula so as to be 5 cm, and the upper surface of the sample was made flat.

(4) Next, the weight m _hs is measured together with the sample holder, and the sand and distilled water contained in the sample holder are calculated from the weight ratio of the sand and distilled water measured in (2) above. The amount of each was determined. Then, to calculate the water content ratio w and the saturation S _r of the sample using equations 4 and 5. Here, _Vw is the volume of water added to the sample (unit: cm ³ ).

(Preparation of fully saturated sample)
(1) A procedure for preparing a fully saturated sample will be described. First, about 2 cm of distilled water was put into the sample holder. The sample was deposited about 1 to 1.5 cm while dropping the sample in water.

(2) Next, the sample of (1) was put in a desiccator and vacuum deaeration was performed (about 7 minutes). By this work, unnecessary bubbles and the like were removed, and a completely saturated sample was prepared. The sample of the sample holder taken out from the desiccator was sufficiently filled with a lead weight and a metal spatula.

(3) Thereafter, (1) and (2) were repeated as many times as necessary (about 3 to 4 times).

(4) After the sample reached about 80% of the height of the sample holder, it was placed in a desiccator for about one night and vacuum deaeration was performed. At this time, a sample filled with distilled water in another container (beaker or the like) was simultaneously degassed.

(5) The sample holder which had been deaerated for about one night was taken out of the desiccator, and sufficiently filled with a lead weight and a metal spatula. Furthermore, add the sample deaerated in another container until the sample holder is fully filled, fill with pressure until it exceeds the upper end of the sample holder, adjust with a plastic spatula so that it becomes 5 cm, and Flattened.

(6) The weight m _hs was measured together with the sample holder and recorded as the weight of the fully saturated sample.

(7) After completing various measurements, the sample was transferred from the sample holder into a bowl in which the dry weight had been measured in advance. At that time, everything was poured into a bowl while pouring distilled water so that no sample remained. Thereafter, the sample was placed in a drying oven at 110 ° C. together with the bowl and dried. The weight of the dried sample is measured, completely from the difference between the weight of the sample saturated to calculate the water content ratio w and the saturation S _r of the sample recorded.

(Making mixed sample)
A procedure for preparing a mixed sample will be described. In order to see changes in physical properties due to porosity, a sample was prepared by mixing No. 3 silica sand with a large particle size and Toyoura standard sand with a small particle size. As for the preparation method, before filling the sample holder or preparing the sample in the bowl, the respective weights were measured so as to obtain the set mixing ratio, and the ratios were adjusted. Subsequent preparation methods were performed in accordance with the preparation of the dry sample and the preparation of the water-containing sample. No. 3 silica sand with a large particle size and Toyoura standard sand with a small particle size are easy to separate, so we tried to pack them in the sample holder as much as possible.

Next, the measurement procedure will be described.
(Measurement of correlation between saturation and physical properties)
Using the five types of artificial soil samples described above, samples with different soil moisture saturation levels were prepared by changing the water content in each sample, and the tests were performed. Six types of saturation were prepared: dry state (0%), about 20%, about 40%, about 60%, about 80%, and saturated state (100%).

  First, measurement is performed in a dry state, and then the water is added to the dry sample in the manner described in the measurement of the moisture-containing sample to prepare a sample having a saturation level of about 20%. By returning to the bowl and adding water, a sample with a degree of saturation of about 40% was created and measured in this manner, and measurements were sequentially made up to a degree of saturation of about 80%. Finally, the sample was saturated using a desiccator (approximately overnight), and the sample was measured in a fully saturated state. In addition, measurement was performed by adding a set saturation according to the sample.

(Examination method for data reproducibility)
When performing measurement under each condition, a sample that had undergone a series of measurements was taken out and put back in to perform a series of measurements. Measurement was performed while confirming whether reproducible data was obtained by repeating three times for each sample.

  For a fully saturated sample, vacuum degassing was involved and a lot of time was required, so only one measurement was performed.

(Measurement method of specific resistance)
The electric wires of the electrodes 14a, 14b, 15a, 15b in the sample holder were connected to a specific resistance measuring device (Mini-OHM, manufactured by Applied Geology), and the specific resistance of the sample was measured. The measurement was performed about three times, and the average value was adopted as the value. However, measurement was not performed when electricity did not flow through the sample due to drying of the sample. Table 4 shows the specifications of the measurement equipment.

(Measurement method of thermal resistance)
The probe inserted from the hole 18 of the sample holder was connected to a thermal conductivity meter, and the thermal conductivity was measured. The measurement was performed about 3 times, and the average value was adopted. Note that the measurement conditions (heating time, intensity of heating) were measured after setting them appropriately according to the type of sample, the degree of saturation, and the like. Table 5 shows the specifications of the measurement equipment.

Next, measurement results of various physical property values using saturation as a parameter will be described.
(Relationship between saturation and specific resistance)
Tables 6 to 14 show the measured specific resistance values at the respective saturation levels set. Table 6 shows measured values for recycled sand (RC-10), Table 7 shows measured values for washed sand, Table 8 shows measured values for No. 3 silica sand, Table 9 shows measured values for No. 5 silica sand, Table 10 shows Measurement values for Toyoura standard sand, Table 11 shows measurement values for No. 8 silica sand, Table 12 shows measurement values for loam, Table 13 shows measurement values for silt, and Table 14 shows measurement values for Kibushi clay. Vs is the S wave velocity, ρ is the specific resistance, k is the thermal conductivity, and g is the thermal resistance. FIG. 5 shows the relationship between saturation and specific resistance. In all samples, a clear negative correlation between the degree of saturation and the specific resistance was observed on the logarithm.

  Compared with all samples, the degree of saturation and specific resistance shift lower as the particle size becomes smaller on both logarithms. No. 3 quartz sand has the highest resistivity under the same saturation conditions, No. 5 quartz sand, Toyoura standard sand, It is lower in the order of silt and clay.

(Relationship between saturation and specific thermal resistance)
Tables 6 to 14 show the thermal conductivity measured at each set saturation and the specific thermal resistance derived from the values. FIG. 6 shows the relationship between saturation and intrinsic thermal resistance. In each sample, there was a negative correlation between the saturation and the specific thermal resistance, and the specific thermal resistance decreased sharply until the saturation was 0 to 20%, but when the saturation was higher than that, The decline will be gradual.

  When all samples are compared, a difference depending on the sample is seen when the degree of saturation is 0 to 20%.

  Next, the correlation between specific resistance and thermal resistance will be examined. Tables 6 to 14 and FIG. 3 show the correlation between specific resistance and thermal resistance. As is clear from Tables 6 to 14 and FIG. 3, a clear positive correlation is observed between the specific thermal resistance and the specific resistance. shift. There is a large difference between sand samples and silt / clay samples.

As a result of the above laboratory test, the first relationship 1 between the physical property value (specific resistance) obtained by the geophysical exploration method and the specific thermal resistance can be summarized as follows.
(1) The specific resistance shows a good correlation with the specific thermal resistance, and the thermal resistance tends to increase as the specific resistance decreases.
(2) The correlation between the specific resistance and the specific thermal resistance differs depending on the sample.
(3) The specific resistance of the sand sample is one order or more higher than the silt / clay sample for the same specific thermal resistance value.

  From the above, it was confirmed that if the type of soil can be specified, the thermal resistance distribution can be calculated from the specific resistance distribution by the electric exploration method.

  Next, from the relationship between the specific resistance ρ and the specific thermal resistance g, the horizontal axis is plotted on a logarithmic graph of the specific resistance and the vertical axis is plotted on the logarithmic graph of the specific thermal resistance to obtain a power approximation formula for each sample (FIG. 3). 6 empirical formulas were obtained. Here, a and n are constants depending on the soil.

<Equation 6> g = aρ ⁿ

  Both samples have a positive correlation on both logarithms, and there is a tendency to shift to the upper left as the soil constituent particles become smaller. The constant a is 1.65 to 6.05 for sand samples and 11.9 to 12.5 for clays and silts, and there is a large difference between them. On the other hand, the constant n is 0.313 to 0.451 for sand samples and 0.477 to 0.562 for silt / clay, and the difference is small with respect to the constant a. By identifying the type of soil, Equation 6 can be used to determine the specific thermal resistance.

1 Relationship between specific resistance and specific thermal resistance (first relationship)
2 Storage means 3 Input means 4 Calculation means 5 Program for measuring specific thermal resistance 8 Relation reading section 9 Measurement data reading section 31 Second relation

Claims (6)

  The relationship between the specific resistance of the soil and the specific heat resistance is determined in advance for each type of soil, the specific resistance of the soil is actually measured at the survey site, and the measurement result is applied to the above-mentioned relationship where the types of soil match. A method for measuring the specific heat resistance of soil, wherein the specific heat resistance at the survey site is obtained.   Storage means for storing the relationship between specific resistance and specific thermal resistance obtained in advance for each type of soil, and input means for reading the soil type at the survey site and the measured value of the specific resistance of the soil at the survey site And a calculation means for obtaining the specific thermal resistance by applying the measured value to the relationship in which the types of soil coincide with each other.   At least means for reading the relationship between the specific resistance and the specific thermal resistance obtained for each kind of soil pre-stored in the storage means, the ratio of the soil type at the survey site and the newly measured soil ratio at the survey site A program for measuring the specific thermal resistance of soil for reading the measured value of resistance and applying the measured value to the relationship in which the types of soil match to determine the specific thermal resistance.   The relationship between the specific resistance of the soil and the specific heat resistance is determined in advance for each type of soil and is set as the first relationship, and the relationship between the type of soil and the S wave velocity is determined in advance for each type of geology As a relation, the soil resistivity and S wave velocity are actually measured at the investigation site, and the measured value of the S wave velocity is applied to the second relationship with the same geological type to estimate the type of soil, A specific heat resistance measurement method for soil, wherein the specific heat resistance at the investigation site is obtained by applying the measured value of the specific resistance to the first relationship that matches the estimated kind of soil.   A memory storing a first relationship between specific resistance and specific thermal resistance obtained in advance for each soil type and a second relationship between soil type and S wave velocity obtained in advance for each geological type Means, input means for reading the measured geological type of the survey site, the measured value of the S wave velocity of the soil at the survey site and the measured value of the specific resistance of the soil at the survey site, and the measured value of the S wave velocity A calculating means for estimating the specific thermal resistance by applying the second relation of matching type to estimate the kind of soil and applying the measured value of the specific resistance to the first relation of matching the estimated kind of soil. An apparatus for measuring the specific thermal resistance of soil, comprising: At least the first relationship that is the relationship between the specific resistance and the specific thermal resistance obtained for each type of soil stored in advance in the storage means, and the soil type and S wave velocity that are determined in advance for each type of geology Means for reading the second relationship which is the relationship between the soil, the type of geology at the survey site, the measured value of the S wave velocity of the soil newly measured at the survey site, and the ratio of the soil newly measured at the survey site Means for reading the measured value of the resistance, applying the measured value of the S wave velocity to the second relationship in which the geological type matches, estimating the soil type, and matching the estimated first soil type A program for measuring the specific heat resistance of soil for causing the computer to function as a means for obtaining the specific heat resistance by applying the measured value of the specific resistance of the soil to the relationship.