JP2867333B2 - Determination method of weathering degree of rock - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measurement and analysis method for determining the degree of weathering of rock mass.

[0002]

2. Description of the Related Art Various scales of rock excavation slopes have appeared in the construction of dams and expressways, open pit mines, and the like, and safety management during construction and maintenance after construction have become important issues.

Conventionally, various in-situ measurements (rock displacement meter, ground surface inclinometer, underground strain meter, borehole inclinometer, etc.) have been performed as measurement items for evaluating the stability of rock slopes. .

[0004]

These measured values give information on the location where the instrument is installed, and cannot be said to be representative of the entire slope. In addition, it is necessary for a person to approach a slope even if the slope is dangerous during measurement. Further, the judgment result may differ depending on the engineer.

On the other hand, there is a method in which the elastic wave velocity is measured by an elastic wave exploration device or the like, and the degree of weathering is evaluated by comparing it with the elastic wave velocity of the rock specimen. It is necessary to work on a slope such as installing a shaker and hitting the surface, and the obtained elastic wave velocity information is
Limited to the survey line and its depth direction.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for determining the degree of weathering of a rock, which can solve the disadvantages of the conventional example and can safely and efficiently evaluate the elastic modulus and stability of a rock slope.

[0007]

In order to achieve the above object, the present invention measures a rock surface using a thermal infrared imaging device, further performs a meteorological measurement in the vicinity, and after the measurement, a heat balance model of a rock surface layer. Input the temperature, wind speed, and solar radiation data to calculate the temperature change of the rock surface by changing the thermal inertia value of the rock, calculate the thermal inertia suitable for the actually measured surface temperature, and calculate the thermal inertia using the porous material model. The purpose is to determine the Young's modulus of the rock mass from the drilling and to use the obtained Young's modulus to perform excavation analysis by a numerical analysis method such as the finite element method and to examine local and total failures It is.

[0008] The thermal inertia and the rock surface temperature are as follows. As the rocks weather, the porosity increases and the density decreases. Along with this, the Young's modulus and rigidity of the rock mass decrease continuously. On the other hand, under conditions where the temperature changes periodically, such as on the ground, the magnitude of the temperature change on the rock surface is governed by its thermal inertia (Formula 1 below).
Here, ρ is density, c is specific heat, and λ is thermal conductivity.

[0009]

[Formula 1]

The surface temperature of a substance having a large thermal inertia is less likely to change. This thermal inertia also causes the weathering of the rock to progress,
It is thought to decrease continuously. Weathered bedrock has a smaller thermal inertia than intact bedrock, so the surface temperature change is relatively large. If the relationship between the thermal inertia and the elastic modulus is given quantitatively, it is possible to know the elastic modulus by measuring the thermal inertia of the rock.

According to the present invention, the surface temperature of the rock slope can be measured in a non-contact manner by the thermal infrared imaging device, so that it is not necessary for a human to approach the dangerous slope, and the weathering can be safely judged. It is also possible to investigate at night.

Further, since the surface temperature of the rock can be recorded as an image by the thermal infrared imaging device, the degree of surface weathering can be determined. In addition to this, the thermal inertia of the rock can be inversely analyzed from the change in the surface temperature of the rock, and further converted to the Young's modulus by the porous body model.

The items to be investigated are only the temperature measurement of the rock surface using the thermal infrared imaging device, and the meteorological measurement such as temperature, wind speed, solar radiation, etc., and require less labor than conventional methods based on elastic wave exploration.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a flowchart of the method for determining the degree of weathering of a rock according to the present invention.

First, the surface temperature of the slope to be analyzed and the weather near the slope are measured. Two-dimensional temperature information can be obtained from the surface temperature change of the rock by using a thermal infrared imaging device.
In the case where the target slope is rich in irregularities and local shading occurs, nighttime measurement is performed. The measurement period is about six hours to one day.

After the measurement, the temperature, wind speed, and solar radiation data, which are the results of meteorological measurements near the slope, are input to the heat balance model of the slope surface layer, and the temperature change of the rock surface is calculated by changing the thermal inertia value of the rock. . Then, the thermal inertia that matches the actually measured surface temperature is calculated back.

Next, the elastic modulus (Young's modulus, Poisson's ratio, etc.) is converted based on the porous body model. This analysis takes only a few hours on a personal computer.

Next, the rock mass is modeled by a porous body, and the relationship between the thermal inertia and the elastic modulus is examined. Several theoretical approximations for the thermal conductivity and the elastic modulus of a homogeneous porous body composed of spherical pores have been individually proposed. First, the following Eucken equation is known as a theoretical equation of the thermal conductivity λ of a porous body.

[0019]

[Formula 2] Where ε: porosity (0 ≦ ε ≦ 1), K = λ _s / λ _a ,
λ _{s is} the thermal conductivity of the substrate portion, and λ _a is the thermal conductivity of the gas phase in the gap.

The thermal inertia I of the porous body is given by ignoring the thermal inertia of air.

[Equation 3] Here, I _s is the thermal inertia of the solid phase.

The following equation is a theoretical equation for the elastic modulus of a dilute dispersion porous body composed of spherical pores.

(Equation 4)

(Equation 5)

Here, ε is the porosity, Ks and K are the bulk modulus of the solid and the porous body, respectively, and Gs and G are the rigidity of the solid and the porous body, respectively. As the porosity increases, mutual interference between pores occurs. Yamamoto et al. Have proposed an NSC (new self-consistent) scheme as a method of calculating the elastic modulus in this case. This is because K and G of the porous material are obtained from the theoretical formula of the dilute dispersion porous material with respect to the minute porosity increment, and these values are again substituted into Ks and Gs in [Equation 4] and [Equation 5] to repeatedly calculate. This is a method of calculating the elastic modulus for an arbitrary porosity.

The relationship between the thermal inertia and the Young's modulus of the porous body is given as shown in FIG. 2 by linking the equation of [Equation 3] with the elastic modulus obtained by the NSC scheme using the porosity as a parameter. However, this is the case when the Poisson's ratio of the solid phase is 0.25. According to FIG. 2, in order to know the Young's modulus from the thermal inertia of the rock, the thermal inertia Is and the Young's modulus Es of the solid phase are required. These values should be obtained by laboratory tests when near-unweathered rock samples can be obtained at the site. If sampling is difficult, use the values in the literature.

In this way, the Young's modulus of the bedrock is obtained from the thermal inertia by the porous body model, and after the Young's modulus of the target slope is obtained, the obtained Young's modulus is used to perform finite element method (FEM) or the like. It is possible to perform slope stability analysis, study local and total failures, and evaluate slope stability in about a few days.

[0025]

EXAMPLES As a test to test the effect of the present invention, the relationship between the thermal inertia and the elastic modulus of cellular mortar having various porosity was experimentally determined as an examination by a laboratory experiment.
The result of comparison with the theoretical formula will be described.

(Experimental Method) In the experimental method, the temperature in the constant temperature chamber was periodically changed, and the change in the surface temperature of the cell mortar specimen was examined. Then, the thermal inertia was determined by fitting the surface temperature of each specimen to the theoretical solution of the one-dimensional heat conduction equation. Further, a uniaxial compression test was performed using a test piece having the same composition as the specimen used for the heat transfer experiment, and the Young's modulus was measured.

The cell mortar was prepared by a mix foam method. The mortar was mixed for all specimens.
/ C = 70% and S / C = 3. A thermocouple was embedded in each specimen in advance. After kneading, the mixture was air-dried at a temperature of 20 ° C. for 5 weeks. Table 1 below shows the density and porosity of each specimen.

[0028]

[Table 1]

After curing, heat transfer test models shown in FIGS. 3 and 4 were prepared. As shown in the figure, the side and bottom surfaces of the specimen were covered with a heat insulating material 3 (hard urethane foam) having a thickness of 10 cm so that heat could be transferred one-dimensionally. In the figure, 1 indicates a thermocouple and 2 indicates a bubble mortar.

In the heat transfer experiment, the temperature in the constant temperature chamber was changed in a sinusoidal waveform at a constant period, and the temperature change on the surface of the test specimen was measured. Air was forced to circulate in the constant temperature chamber by a fan. The cycle of the temperature change is one day, and the half amplitude is about 9
° C. The average wind speed in the constant temperature room is 0.25 m / s,
The relative humidity in the room was about 60%.

(Experimental Results) The above Table 1 shows the temperature amplitude and Young's modulus of the 28-year-old material when the surface temperature of the test sample was periodically in a steady state. In addition, FIG. 1 and No.
7 shows an example of the surface temperature change.

From these experimental results, the thermal inertia of the specimen was estimated. In this method, the measured value of the surface temperature change of each specimen was matched by the simplex method to the theoretical solution of the surface temperature of the semi-infinite medium when the outside air temperature fluctuated periodically, and the thermal inertia value was obtained. In this case, the heat transfer coefficient is Rowley
Based on Algren experimental ^{results, 11kcal / (m 2 · h} ·
° C) [12.8 W / (m ² · K)]. Table 1 shows the thermal inertia determined by this method. FIG. 2 also shows the theoretical curves of the thermal inertia and Young's modulus of the porous body and the test results. Although the test results vary, the test values are distributed almost along the theoretical curve.

Next, the test results for the in-situ rock will be described. In the survey, a thermal image was taken for about one day to investigate the surface temperature change of the rock slope, and at the same time, the temperature, wind speed, and solar radiation were measured. In order to investigate the mechanical properties of rocks, dolomite rock blocks were collected from the site and subjected to indoor rock tests. In the analysis, based on these data, the thermal inertia value of the dolomite constituting the survey slope was calculated backward, and the elastic modulus was calculated from the thermal inertia based on the porous body model. Then, the stability of the slope was evaluated by the finite element method (FEM) using the obtained Young's modulus.

As a numerical analysis method in civil engineering,
The finite element method (FEM), boundary element method (BEM), discrete element method (BEM), discretized limit analysis method (RBSM),
Key block theory and the like can be mentioned. Finite element method (FE
M) was developed in the field of aeronautical engineering in the 1950s, and has since spread to the fields of geotechnical engineering and rock engineering, where modeling of ground and structures with complex structures and conditions is possible. This is a technique that can be applied in a wide range.

The excellent features of the FEM as a numerical analysis technique are as follows. 1) Even if the geometric shape of the region (ground, tunnel) to be analyzed is complicated, modeling can be performed by combining various finite elements, and boundary conditions can be set according to the actual shape. 2) Analysis is possible even when elements having various properties are mixed and used, both geometrically and materially. Therefore, it is possible to model complicated ground conditions and structures made of various materials in a form close to reality. 3) Generally, the discretization and formulation of the basic equations are relatively easy. Therefore, it is easy to consider geometric non-linearity and material non-linearity. 4) In the formulation for structural analysis, Ritz-Galer
Since it is based on a direct analysis method such as the kin method, it satisfies the principle of virtual work and has physical consistency. 5) Extensibility is high because the discretization method is unified. For example, it can be extended to a coupling problem between a structural system and a fluid system.

The procedure of stress / deformation analysis by FEM is as follows. 1) The analysis target is divided into a finite number of elements by a certain virtual boundary line (each element is connected to each other only at a finite number of nodes on the boundary). Based on the relationship between the force acting on the node of the element and the displacement caused by that, and the condition of continuity between the elements, a condition for balancing the force at each node is created. 3) The equilibrium condition equation is a multi-element simultaneous equation in which the nodal displacement is an unknown number, and the nodal displacement can be obtained by solving this equation under given boundary conditions and load conditions. 4) The strain of each element is obtained from the nodal displacement, and the stress is further obtained. Therefore, if you enter the information (structure data, material property data, load data, boundary conditions, etc.) necessary for these operations,
Information (displacement, stress, etc.) that the user wants to know is output.

The following are the basic ground constants (physical property values) used for stress deformation analysis (linear elasticity analysis) by FEM. Deformation coefficient, adhesive strength, Poisson's ratio, internal friction angle,
Unit volume weight

The test contents of the field experiment are as follows. [Test Items] 1. Thermal imaging 2. Solar radiation, wind speed, temperature measurement Indoor rock test [Experimental site] The experiment was performed using the remaining wall of an open pit at a mine. The mining pit is almost a square depression,
The survey site is the remaining northwest slope. The slope height of this remaining wall is about 150 m, the slope width is about 200 m, and the slope is about 45 °
It is. There are small steps every few meters to several dozen meters in height. Geology is composed of Paleozoic dolomite and limestone.

The thermal infrared image was taken from 5:00 pm to 11:00 am the next day. An infrared camera, which is a thermal infrared imaging device, was fixed at one place, and images were taken at 30-minute intervals during the day when slope surface temperature changes were large, and at hourly intervals at night. The infrared camera was installed at a point about 200 m away from the slope to be photographed. Temperature, wind speed, and solar radiation were observed during the thermal imaging period. The measurement of solar radiation was performed on a horizontal plane by a thermocouple type pyranometer. The output of the pyranometer is
It was output as an integrated value every 10 minutes by an analog integrator.
Temperature and wind speed were measured at 5 minute intervals. Air temperature was measured with a platinum resistor. The sensor was housed in a stainless steel container to reduce the effects of solar radiation. The survey results are shown below.

(Slope Surface Temperature) FIG. 6 shows a visible image of the thermal image capturing range, and FIGS. 7 and 8 show examples of thermal image capturing. Photograph FIG. 7 is a thermal image at 5:00 pm when photographing was started. Photo 8
Is a thermal image of the next day at 5:00 am, which is a time zone in which the air temperature shows the lowest temperature before sunrise.

Next, the average value and the standard deviation of the slope surface temperature in the region indicated by the thick frame α in FIG. 6 were examined. The result is shown in FIG. FIG. 10 shows an example of the temperature distribution histogram of this area (5:00 pm).

Although the actual slope shape is rich in irregularities due to the presence of small steps, its temperature distribution is almost normal as shown in the histogram of FIG. Therefore, a slope having an average gradient including this small step is considered, and the surface temperature is represented by the average temperature of the area. Also, since the target slope faces northwest, it is difficult to receive solar radiation, and it is considered that the temperature of the slope surface is mainly controlled by heat transfer with the outside air.

(Temperature, wind speed, solar radiation) As a measurement of weather conditions such as temperature, wind speed, solar radiation, etc.
Temperature fluctuation range during the measurement period is about 9 ° C, wind speed is 3-6m /
s. FIG. 11 shows temporal changes in temperature and wind speed moving averaged over a 30-minute width. FIG. 12 shows the time change of the amount of solar radiation (integrated value for 10 minutes).

(Rock test results) In order to estimate the rock strength of dolomite constituting the slope, tests shown in Table 2 below were performed.

[0045]

[Table 2]

(Sampling and Preparation of Test Specimen) A rock block as a sample was collected from a boulder in the test site. The rock type is dolomite. Specimens for rock testing were prepared by performing core boring of φ50 mm on these rock blocks and shaping the obtained cores. A summary of the test results is shown in Table 3 below.

[0047]

[Table 3]

Using the data obtained from thermal images and meteorological measurements as the analysis results, the thermal inertia value of the dolomite constituting the remaining wall of the mine was inversely calculated. FIG. 13 shows the calculated values of the slope surface temperature for several types of thermal inertia and the average values of the surface temperatures in the region indicated by the thick rectangular frame α in FIG.

The thermal inertia value that best satisfies the measured surface temperature was determined as a value that minimizes the error represented by the following equation (6). As a result, 36 kcal / (m ² · ° C. · h ^0.5 ) [2
The value of ^{500J / (m 2 · s 0.5} · K)] was obtained.

[0050]

(Equation 6) Where θ _t ^cal : the calculated surface temperature at time t,
θ _t ^obs : measured surface temperature at time t

Comparing the graph of the optimum calculated value and the measured value by the thermal image, the temperature change patterns of the night data from the start of measurement to 5:00 am of the next day are almost the same. However, after 5 o'clock, the error in the calculated value has increased. This is probably because the effects of solar radiation are not well represented in the calculation model.

From the thermal inertia value thus obtained, the elastic modulus was calculated using a porous material model. At this time, the elastic modulus was determined by a dry porous material model ignoring the effect of water content. No spring water was observed on the rock surface in the analysis area, and this assumption is considered to be almost valid. As the thermal inertia Is of the solid phase of unweathered dolomite, the value in the literature was used because the thermophysical property test of the rock was not performed. The values obtained from the rock test results were used for the density and Young's modulus of the solid phase. These values are summarized in Table 4.

[0053]

[Table 4]

Limestone and dolomite have a greater degree of heterogeneity in the rock texture than granite and the like, and the physical property values in the table are distributed with a certain width as shown in parentheses. The Young's modulus of the dolomite constituting the remaining wall is converted in consideration of the thermal inertia value and the Young's modulus of the solid phase of the unweathered dolomite.

FIG. 14 shows the relationship between the thermal inertia of the dry porous body and the Young's modulus. The horizontal axis represents the ratio of the thermal inertia Is of the solid phase to the thermal inertia I of the porous body. The vertical axis represents the ratio of the Young's modulus Es of the solid phase to the Young's modulus E of the porous body.

As described above, the thermal inertia of the dolomite distributed on the slope is 36 kcal / (m ² · ° C. · h ^0.5 ) [250
^{0J / (m 2 · s 0.5} · K)] and so are sought,
I / Is = 0.74 (0.69 to 0.86). From FIG. 14, the ratio of the Young's modulus E / Es of the porous body to this thermal inertia ratio is obtained.
0.61 (0.53 to 0.77). When this E / Es value was multiplied by Es in Table 4, a value of 48 GPa (31 to 80) was obtained as the Young's modulus of the dolomite constituting the remaining wall.

The stability of the slope is evaluated. (Analysis method) Using the Young's modulus obtained by the thermal inertia method, the stability of the slope to be investigated was evaluated by FEM. For the analysis, excavation analysis was performed on the cross section of the slope by two-dimensional linear elastic analysis (plane strain problem). Basically, it is a continuum analysis and does not consider the effect of macroscopic discontinuities on slope stability. The initial stress was determined by a weight analysis. That is, the stress distribution was calculated by applying only its own weight to the ground before excavation. However, at this time, the lateral pressure coefficient was set to 0.99. In the excavation step, displacement and stress distribution on the slope were calculated by applying external force equivalent to excavation to nodes on the excavated surface as collective excavation.

(Analysis Model) FIG. 15 shows an analysis model and boundary conditions.

(Destruction Criteria) As a destruction criterion, Mohr-Coulomb's criterion was used. However, the following assumptions were made for the strength constant. Internal friction angle φ regardless of rock mass deterioration
Is assumed to be constant, and the adhesive force c changes from the value of the fresh rock piece to zero in proportion to the reduction ratio E / Es of the Young's modulus of the rock. Although this assumption does not oversimplify the actual weathering phenomenon, it was adopted as a first approximation.
The local safety factor was defined as the ratio between the distance from the center of the molding circle to the fracture line and the maximum shear stress, as shown in FIG.

(Input Physical Property Values) Table 4 below shows the ground constants used in the analysis. The minimum value obtained by the thermal inertia method was used as the Young's modulus of the ground. In addition, as described in the previous section, the adhesive strength of a fresh rock piece was determined to be 400 tf based on Reference 8.
/ M ² [3.92 MPa], which was obtained by multiplying this by the minimum value 0.53 of E / Es obtained by the thermal inertia method.

[0061]

[Table 5]

(Analysis Results) FIGS. 17 to 19 show the analysis results. FIG. 17 is a displacement diagram of the remaining wall. The maximum value of the change is 12.5 mm at the tip and the maximum shear strain is about 0.02%. FIG. 18 is a main stress distribution diagram. Fig. 19 is a contour diagram of the local safety factor.
Met.

The Young's modulus obtained by the thermal inertia method was applied to the entire slope, and the rock slope at the test site was treated as a continuum, and two-dimensional excavation analysis was performed by FEM. As a result, the result that the stability was maintained as a whole slope was obtained.

When the Young's modulus of a slope is determined by the thermal inertia method, the Young's modulus Es of intact rock is required, and the value directly affects the estimation accuracy of the Young's modulus of the rock.
This time, the value was determined from a small number of rock test results,
It is conceivable that the actual ground Es is lower than the test value. When the strength constants c and φ are determined by the thermal inertia method as described in the section on fracture criteria, φ is constant and c is E /
It was assumed that it decreased in proportion to Es. It is also considered possible to introduce a fracture criterion other than the Mohr-Coulomb standard, for example, a fracture criterion based on the maximum shear strain.

As a result of conducting an on-site application experiment of the thermal inertia method of the present invention on the remaining wall of a limestone open pit mine, the following was found. 1. As a result of analyzing the thermal inertia value of the rock mass by the slope heat balance model, I was 36 kcal / (m ² ° C · h ^0.5 ) [2500 J / (
m ² · s ^0.5 · K)]. This value is 69 to 86% of the thermal inertia Is of intact rock. This I
The / Is value can be a relative index for evaluating the degree of rock degradation. 2. The imaging time zone of the rock surface temperature is advantageous for thermal inertia measurement because it is not necessary to consider the influence of solar radiation during the night than during the day. The Young's modulus of the rock mass was converted from the thermal inertia value by the porous material model, and values of 0.53 to 0.77 were obtained as E / Es. Therefore, the Young's modulus is reduced to a maximum of 53% for intact rock. The Young's modulus obtained from the rock test was 31 to 80 GPa. 4. Two-dimensional elastic FE considering slope of test site as continuum
As a result of M analysis, the minimum value of the local safety factor was 1.51 at the tip.

[0066]

As described above, the method for determining the degree of weathering of a rock according to the present invention is capable of safely and efficiently evaluating the elastic modulus and stability of a rock slope, and has the following effects.

Since the surface temperature of the rock slope can be measured in a non-contact manner by the thermal infrared imaging device, it is not necessary for a person to approach the dangerous slope, and the weathering can be safely judged. It is also possible to investigate at night.

Further, since the surface temperature of the bedrock can be recorded as an image by the thermal infrared imaging device, the degree of weathering can be determined. In addition to this, the thermal inertia of the rock can be inversely analyzed from the change in the surface temperature of the rock, and further converted to the Young's modulus by the porous body model.

The survey items are only the temperature measurement of the rock surface using the thermal infrared imaging device, and the meteorological measurement such as temperature, wind speed, solar radiation, etc., and are less troublesome than the conventional method using elastic wave exploration.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of a rock weathering degree determination method according to the present invention.

FIG. 2 is a graph showing a relationship between thermal inertia and a Young's modulus of a porous body.

FIG. 3 is a side view of a heat transfer test model.

FIG. 4 is a plan view of a heat transfer experiment model.

FIG. 5 is a graph showing changes in surface temperature of specimens No. 1 and No. 7.

FIG. 6 is a front view showing a visible image in a thermal imaging range.

FIG. 7 is a front view showing an example of capturing a thermal image at 5:00 pm.

FIG. 8 is a front view showing an example of capturing a thermal image at 5:00 am the next day.

9 is a graph in which the average value and the standard deviation of the slope surface temperature in a region indicated by a thick frame α in FIG. 6 are examined.

FIG. 10 is a graph showing an example of a temperature distribution histogram (at 5:00 pm) of a region indicated by a thick frame α in FIG. 6;

FIG. 11 is a graph showing changes in temperature and wind speed.

FIG. 12 is a graph showing a temporal change in the amount of solar radiation.

FIG. 13 is a graph showing the inverse calculation of thermal inertia.

FIG. 14 is a graph showing thermal inertia and Young's modulus of a porous body.

FIG. 15 is an explanatory diagram showing an analysis model and boundary conditions.

FIG. 16 is an explanatory diagram for defining a local safety factor.

FIG. 17 is a displacement diagram of a remaining wall as a result of analysis.

FIG. 18 is a main stress distribution diagram as a result of analysis.

FIG. 19 is a contour diagram of a local safety factor as an analysis result.

[Explanation of symbols]

 1. Thermocouple 2. Bubble mortar 3. Thermal insulation

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G06F 17/18 G06F 15/36 Z (73) Patent holder 000213909 Asahi Kohyo Co., Ltd. 3-1-1 Higashiikebukuro, Toshima-ku, Tokyo (73) Patent holder 596118600 NEC Sanei Co., Ltd. 1-57, Tenjin-cho, Kodaira-shi, Tokyo (73) Patent holder 391007747 Kowa Corporation 6-1, Shinkocho, Niigata-shi, Niigata (73) Patent holder 596139993 Ken Consultants 11-27, Wakita Honcho, Kawagoe-shi, Saitama Prefecture (73) Patent owner 592059736 Daito Construction Industry Co., Ltd. 1050, Hieda, Akie, Oaza, Miyazaki-shi, Miyazaki (72) Inventor Hirofumi Miki 1-1-1, Asahi, Tsukuba-shi, Ibaraki (72) Inventor: Shinhiro Mihara Tsukuba, Ibaraki 1-chome, Asahi 1-chome Construction (72) Inventor: Mitsuhiro Furuta, 1-1, Asahi, Oaza, Tsukuba, Ibaraki Pref.Construction: (72) Inventor: Morihiro Ishibashi 2304 Takasaki, Kashizaki-cho, Inashiki-gun, Ibaraki Japan Nippon Koei Co., Ltd. Central Research Laboratory (72) Inventor Noriyuki Arai 2570-4 Shimotsuruma, Yamato-shi, Kanagawa Nishimatsu Construction Engineering Research Laboratory Co., Ltd. 5-11-3, Shinbashi, Minato-ku Toko Construction Corporation (72) Inventor Kazunori Takada 1-3-3-203 Hikarigaoka, Nerima-ku, Tokyo (72) Inventor Tetsushi Matsunaga 1-57, Tenjincho, Kodaira-shi, Tokyo NAC Sanei Co., Ltd. (72) Inventor Yuzo Kobayashi 5295 No.2, Komachicho, Niigata City, Niigata Prefecture Kowanai Co., Ltd. (72) Inventor Hiroya Ichikawa 11-27 Wakita Honcho, Kawagoe-shi, Saitama 27 Stock Company (72) Inventor Koichi Shishido 11-27 Wakita Honcho, Kawagoe-shi, Saitama In-house Research Institute Consultants (72) Inventor Hideto Hasegawa 11-27 Wakita Honcho, Kawagoe-shi, Saitama Prefecture In-house Research Institute Consultants (72) Inventor Tatsuro Kawasaki 1050 Hieda, Akae, Oe, Oaza, Miyazaki-shi, Miyazaki Prefecture Daito Co., Ltd. Within the construction industry (58) Field surveyed (Int. Cl. ⁶ , DB name) G01N 33/24

Claims (1)

(57) [Claims] 1. The surface of a rock mass is measured using a thermal infrared imaging device, and weather measurement of the surrounding area is further performed. After the measurement, temperature, wind speed, and solar radiation data are input to a heat balance model of the rock surface layer, and the rock mass is measured. Calculate the temperature change of the rock surface by changing the thermal inertia value, calculate the thermal inertia suitable for the actually measured surface temperature, calculate the Young's modulus of the rock from the thermal inertia using the porous material model, and calculate the obtained Young's modulus. Numerical solution using finite element method etc.
A method for determining the degree of weathering of rock mass, characterized by conducting excavation analysis using analysis techniques and examining local and total failures .