JP3536046B2 - Rock slope stability evaluation method and device by remote observation - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for evaluating the stability of a rock slope by remote observation.

[0002]

2. Description of the Related Art At a construction site such as a road or a dam, rock is exposed by excavation of rock and a rock slope is formed. These rock slopes have a high risk of collapsing over time, and safety management during construction and maintenance of slopes after construction are important issues. In order to carry out safety management and maintenance properly, it is necessary to continuously understand the stability of the exposed rock slope. In order to understand the stability of such rock slopes, various data have been measured for rock slopes.

Conventionally, rock mass data has been obtained by instruments such as a rock mass displacement meter and a ground surface inclinometer, but only data at each measurement point can be obtained, and these data can be obtained for the entire slope. There is no choice but to infer it from the data, and it is difficult to analyze rock characteristics such as the degree of weathering of the rock based on such data, so it is difficult to make an accurate evaluation. Therefore, in order to know the characteristics of the rock mass, the ultrasonic velocity V ₁ of the rock sample obtained from the rock slope is measured by an indoor test, and the elastic wave velocity V ₂ of the surface is measured on the rock slope to measure the Kiretsu coefficient Cr. It was calculated from the equation _{Cr = 1- (V 2 / V} 1) 2 below, "elastic wave velocity - slope gradient relationship diagram" (see FIG. 10; design and construction and engineering properties of Geotechnical Society ed., "rock Application "(April 19, 1974) The Geotechnical Society of Japan p.66
8) (refer to Figure-12.59) and "the relationship between the amount of ground fracture and the slope slope" (see Figure 11; refer to Figure-12.62 described on page 670 of the same document) to evaluate the stability. Has been done. With such an evaluation method, it is possible to obtain highly accurate data because an actual sample is taken from the rock mass or the characteristics are actually measured by an on-site test on the rock mass slope, but highly accurate data can be obtained. Since the work is required, it takes a lot of labor and time, and it is necessary to pay sufficient attention to safety in performing the work. In addition, it is necessary to increase the number of measurement lines in order to measure the entire slope in the field test, and in the room test, if the number of samples is increased to improve the accuracy, it takes time for shaping and measuring the samples. However, there are problems in terms of labor, cost and time when conducting regular evaluations.

Obtaining the measurement data directly from the rock slope in this way has the drawback that it is difficult to evaluate the entire slope only with points or lines, and the work on the slope is difficult. It takes effort and time. Then, the method of measuring the slope by remote observation and evaluating the rock slope based on the measured data is tried. For example, in Japanese Unexamined Patent Publication No. 10-105546, a thermal infrared imaging device is used to measure the surface of rock mass, and at the same time, weather observation in the vicinity is performed, and the temperature, wind speed, and solar radiation data obtained by the observation are input. A heat balance model of the rock mass surface is created, the thermal inertia value of this heat balance model is changed, the temperature change of the rock mass surface is calculated, and the thermal inertia value that matches the measured temperature change of the rock mass surface is obtained. The Young's modulus of rock mass is obtained from the relationship between the thermal inertia value and Young's modulus obtained from the created porous body model, and excavation analysis is performed from the obtained Young's modulus by the finite element method, etc., and local fracture and total fracture are examined. A method for determining the weathering degree of bedrock is described.
With this method, the surface temperature is less likely to change for substances with higher thermal inertia, but it is believed that the thermal inertia will decrease as the weathering of the bedrock progresses, and if the relationship between thermal inertia and elastic modulus can be quantitatively grasped, thermal inertia Is calculated from the change in surface temperature to calculate the elastic modulus, and the weathering degree of rock is determined by remote observation. In the case of this method, it is not necessary to perform the work for measurement on the rock slope, but there is a drawback that a lot of cost and time are required such as model calculation for obtaining the thermal inertia value and experiment using the porous body model. Attempts have been made in various places to measure the rate of temperature change on the rock surface using such a thermal infrared imaging device, and to investigate the weathering degree of the bedrock based on the degree of the temperature change rate. Survey on Weathering Degree of Great Sphinx of Egypt by Sensing "
September 996) Japan Federation of Geological Surveys Associations p.411-4
14, Hiroya Yamamoto "Slope investigation by thermal infrared rays" JSCE "Technical Forum '97" Lecture collection (September 1997) Japan Geotechnical Society Association p.569-572) Based on the correlation between the degree of voids and water content in the vicinity and the rate of temperature change, it is difficult to estimate the mechanical properties related to the strength decrease of rock mass, which is important for evaluating stability.

On the other hand, it is known that there is a correlation between the composition components of rock and the color of the rock surface. By identifying the components in the rock that increase as the weathering of the rock progresses, the color of the rock surface It has been considered to quantify the components from the measured data and use them as indicators of weathering of rocks (Satoru Nakajima, "Global Color Change: Geochemistry of Iron and Uranium") (August 3, 1994).
1st) Near Future Company p.185-191). Based on this idea, various tests have been conducted using actual rock samples. For example, Junji Mange has three different rock samples, granite, sandstone, and volcaniclastic rocks, and the color of the rock is measured using a Lab color system (JIS Z 8729).
Chromaticity L * value of (numerical value of lightness in the range of 0-100; 1
00 is perfect white, 0 is perfect black, a * value (red-green level is quantified; positive direction is red, negative direction is green) and b * value (yellow-blue level is quantified; positive direction) Is yellow and the negative direction is blue)
We analyze the relationship with the weathering degree of rocks (chlorite conversion of biotite, increase of cracks and voids) (applied geology, 38 [6]
(1998) p. 370-385). Also, Yasuga Fujiwara 3
The name is about the weathering degree of the granite, the rock sample and the face were photographed, and the photograph image was analyzed using the Lab color system.
The relationship between a * value and b * value and weathering degree is analyzed (Soil and Foundation, 49 [11] (2001) p.16-18).

[0006]

As described above, attempts have been made to determine the weathering degree of bedrock by remote observation, but in any case, the mechanical properties of the bedrock have a certain extent of broadness. It is difficult to evaluate. In addition, when performing evaluations using rock samples, promptness and simplicity are required from the viewpoints of labor for collecting samples, safety in performing work, and cost and time for conducting tests after sampling. Therefore, it is difficult to put it into practical use as a method for evaluating the actual safety of rock mass. Therefore,
The present invention provides a rock slope stability evaluation method and apparatus for quick and easy evaluation.

[0007]

The rock slope stability evaluation method according to the present invention is a rock slope stability evaluation for evaluating the rock slope stability based on the rock slope data, elastic wave velocity and ultrasonic velocity. In the method, (a) the temperature distribution of the rock slope surface and its change over time are measured, (b) the slope surface is divided into groups based on the data of the temperature distribution and its change over time, and (c) the average slope of each group is calculated. Measure
Obtaining the gradient data of each group, (d) measuring the reflection spectrum of each group, calculating the b * value related to the Lab color system of each group based on the measured data, and (e) changing the temperature of each group. Slope data is measured by analyzing the correlation between rate and b * value and calculating the approximate values of elastic wave velocity and ultrasonic velocity of the group from the b * value for a group having a negative correlation. In addition, the stability of rock slopes is evaluated by calculating approximate values of elastic wave velocity and ultrasonic velocity. Further, the rock slope stability evaluation apparatus according to the present invention, temperature data measuring means for measuring the temperature distribution of the rock slope surface and its change over time, optical data measuring means for measuring the reflection spectrum of the rock slope surface, rock slope What is claimed is: 1. A rock slope stability evaluating device comprising: a gradient data measuring means for measuring three-dimensional coordinates of a surface; and a data analyzing device, wherein the data analyzing device is a temperature distribution obtained from the temperature data measuring means and its time-lapse. Means for grouping slope surfaces based on change patterns, means for calculating average slope data for each group based on data obtained from slope data measuring means, and reflection spectrum data obtained from optical data measuring means Based on the method of calculating the b * value of the Lab color system of each group based on the temperature distribution obtained from the temperature data measuring means A means for calculating the temperature change rate of each group based on the pattern, a means for analyzing the correlation between the temperature change rate of each group and the b * value, and extracting a group having a negative correlation, * Means to calculate the approximate value of elastic wave velocity and ultrasonic velocity based on the value, and evaluate the stable state of the rock slope based on the average gradient data of the extracted group and the approximate value of elastic wave velocity and ultrasonic velocity It has a means to do.

Since the present invention has the above-mentioned structure, the stability can be evaluated by first measuring the rock mass slope itself, so that the labor, time and cost required for analyzing a rock sample can be reduced, and the rock mass can be reduced. Since there is no need to work on the slope, there is no problem in terms of safety. Further, by analyzing the data from each measuring means, the evaluation can be performed quickly, and the data analysis is automatically processed, so that the evaluation work can be easily carried out. As an evaluation method,
Assuming that the rock slopes are not uniform, the rock slopes are divided into groups for evaluation, and the grouping is performed based on the difference in the surface temperature of the slopes and the change over time. As described above, it has been found that the temperature change rate derived from the surface temperature distribution and its change over time has a correlation with the degree of voids in the rock mass and the water content ratio. By dividing the bedrock into
The rock slope can be divided into parts that are similar in area. Here, the temperature change rate represents the amount of temperature change per hour as conventionally used, and is a value obtained by dividing the temperature difference generated within a certain time by the time. However,
Since the rate of temperature change depends on the meteorological conditions at the time of observation-especially the sunshine conditions, the reliability of the parts grouped as having similar physical characteristics becomes a problem. Therefore, in the present invention, the reliability of the grouping is ensured by checking the correlation between the temperature change rate and the b * value for each group. That is, the present inventors have confirmed that there is a negative correlation between the temperature change rate and the b * value, as will be described later, and based on these findings, the temperature change rate and the b * value The groups with a negative correlation between are extracted for evaluation. For groups with a negative correlation between the rate of temperature change and the b * value, it was assumed that the reliability of the data was ensured, and based on the b * value, the elastic wave velocity and ultrasonic velocity It is possible to obtain an approximate value, and when the approximate value is obtained in this way, the Kretz coefficient Cr is derived, and the rock slope is calculated based on the relational diagrams of FIG. 10 and FIG. 11 from the approximate value of the elastic wave velocity, the Kirek coefficient and the gradient data. The stability of can be evaluated. As described above, by combining the rate of temperature change and the b * value, the reliability of the data is ensured from the physical and material viewpoints, and the rock slope is used as a surface for detailed evaluation of each part, A highly reliable evaluation can be obtained.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. FIG. 1 shows an embodiment of a rock slope stability evaluation apparatus according to the present invention. Reference numeral 1 is a control unit of the rock slope evaluation apparatus, which processes the measurement data from the optical distance measuring instrument 5, the spectroradiometer 6 and the thermal infrared imaging device 7 as described later, and processes them in the output unit 3. Output the result. The input unit 4 and the memory unit 2 are connected to the control unit 1. Here, the control unit 1 and the memory unit 2 correspond to an analysis device.

The memory unit 2 is composed of a RAM and a ROM, and stores a program for analyzing the measurement data by the control unit 1, storage of evaluation data and the like corresponding to the relationship diagrams of FIGS. 10 and 11, and processing data. Save temporarily. The output unit 3 is
The processing result and the evaluation result in the control unit 1 are appropriately displayed on a display such as a CRT. The input unit 4 inputs setting data and the like to the control unit 1 with an input device such as a keyboard. The input data is stored in the memory unit 2. Lightwave rangefinder 5
Is a slope distance between two points, which is obtained by reflecting a light wave on the rock slope S and calculating the phase difference between the emitted light wave and the reflected light wave.
By calculating the horizontal distance and the height difference, the three-dimensional coordinates of the surface of the rock slope S can be measured by remote observation. The spectroradiometer 6 measures the reflection spectrum of the light reflected from the surface of the rock slope S by sunlight, and measures the reflection spectrum for each wavelength (for example, 40
In the wavelength range of 0 to 1050 nm, the measurement wavelength is set in 17 steps.) The degree of reflection is measured, and the L * value, a * value and b * according to the Lab color system can be obtained. At the time of observation, by observing the standard white board at the same time and comparing it with the observed value of the object, it is possible to acquire data that does not depend on the illuminance of sunlight or the spectral characteristics. Thermal infrared imaging device 7
Can measure the amount of thermal infrared radiation radiated according to the surface temperature of the rock slope, and measure the temperature distribution over the rock slope and its change over time.

FIG. 2 shows an evaluation flow using the apparatus of FIG. An example of a rock slope as shown in FIG. 3 will be described.
The rock slope in FIG. 3 has a forest W and a grassland P in the upper shaded area, and the rock S is exposed below the forest W and the grassland P.
The bedrock S is leveled in a staircase, and a case where this part is evaluated will be considered. First, the surface temperature distribution of the rock slope S and its change with time are measured by the thermal infrared imaging device 7 (S101). FIG. 5 is a graph of the obtained data for each main measurement point. The vertical axis is the surface temperature and the horizontal axis is the time. Then, the obtained data is analyzed (S102). As an example of the analysis method, there is a method of acquiring difference image data from the surface temperature distribution before and after the time period when the surface temperature is rising and specifying the group area by edge processing. on the other hand,
The three-dimensional coordinates of each measurement point on the rock slope are measured as position data by the lightwave distance measuring device 5 (S103). The surface of the rock slope S is grouped into similar parts based on the analysis result and the position data of the rock surface S (S104). An example of grouping is shown in FIG. The part G surrounded by the dotted line is
The surface area grouped by similar portions is shown. The position data regarding the areas thus grouped is stored in the memory unit 2 and used for the subsequent processing. First, the average gradient data is calculated from the position data of the three-dimensional coordinates for each group (S105). The average gradient data may be calculated from position data of representative points in each group. The reflection spectrum of the rock slope S is measured by the spectroradiometer 6 (S106), and the b * value for each group is obtained (S107). The method of calculating the b * value can be calculated from the following formula, as is already known.

Spectral distribution P (λ) of illumination light, spectral reflectance R (λ) of object, color matching function x (λ) of stimulus value X, color matching function y (λ) of stimulus value Y, stimulus value Assuming that the color matching function of Z is z (λ), the tristimulus values X, Y, and Z are: X = k∫visR (λ) · P (λ) · x (λ) dλ Y = k∫visR (λ) · P (λ) · y (λ) dλ Z = k∫visR (λ) · P (λ) · z (λ) dλ. Here, the constant k is k = 100 / ∫visP (λ) ・ y (λ) d
Let be λ. From the tristimulus values X, Y, and Z obtained in this way
L * value, a * value and b * value are L * = 116f (Y / Yn) -16 a * = 500 {f (X / Xn) −f (Y / Yn)} b * = 200 {f ( Y / Yn) -f (Z / Zn)}. Where f (X / Xn), f (Y / Yn) and f (Z
/ Zn) is as follows. When X / Xn> 0.008856, f (X / Xn) = (X / Xn) ^1/3 Y / Yn> 0.008856, f (Y / Yn) = (Y / Yn) ^1/3 Z / Zn> When 0.008856, f (Z / Zn) = (Z / Zn) ^1/3 X / Xn ≦ 0.008856, when f (X / Xn) = 7.787 (X / Xn) +
When 16/116 Y / Yn ≤ 0.008856, f (Y / Yn) = 7.787 (Y / Yn) +
When 16/116 Z / Zn ≦ 0.008856, f (Z / Zn) = 7.787 (Z / Zn) +
16/116 Xn, Yn, and Zn are tristimulus values for the perfect diffusion surface, and Xn = 95.04, Yn = 100.00, and Zn = 108.89.

Further, the temperature change rate of each group is obtained from the data of the surface temperature distribution and its change over time (S10).
8). For example, in FIG. 5, in the temperature rise time zone from 10:00 to 14:00, which is the range indicated by the vertical solid line, 1
The rate of temperature change per hour can be obtained by dividing the amount of surface temperature change between 0 o'clock and 14:00 by the number of hours.
When calculating the temperature change rate, it is better to avoid the time period when the surface temperature drops as much as possible. And S107 and S
The correlation between the b * value and the temperature change rate of each group calculated in 108 is analyzed (S109). FIG. 6 shows the results of experiments conducted by the present inventors based on rock samples.
Uniaxial compressive strength, forced dry specific gravity, effective porosity and water absorption are plotted on the vertical axis. The graph on the left shows the b * value and the graph on the right shows the rate of temperature change on the horizontal axis. As is clear from these graphs, b * for each parameter
The value and the rate of temperature change have an inverse correlation. That is, the temperature change rate has a negative correlation in the parameter whose b * value has a positive correlation, and the temperature change rate has a positive correlation in the parameter whose b * value has a negative correlation. There is. Therefore, it is inferred that the negative correlation between the b * value and the temperature change rate is fairly universal. The reliability of the data can be secured by looking at the reliability of the b * value and the temperature change rate of each group based on such a correlation. FIG. 7 shows the measurement results of a group in which the vertical axis represents the temperature change rate and the horizontal axis represents the b * value. For groups having such a negative correlation, The process proceeds to the step (S110), and for the other groups, the data is reexamined such as the measurement is repeated. As shown in FIG. 7, the ultrasonic velocity V ₁ and the elastic wave velocity V ₂ are obtained based on the empirical formula using the b * value data for the group having a negative correlation (S11).
1). Regarding the empirical formula, the present inventors have accumulated field experiments on model slopes and laboratory experiments based on rock samples, and have obtained analysis results as shown in FIGS. 8 and 9. According to this analysis result, the elastic wave velocity V ₁ and the ultrasonic velocity V ₁
Both ₂ have a negative correlation with the b * value. The following empirical formula is derived from this correlation. V ₁ = -0.03b * + 1.03 V ₂ = -0.23b * + 6.54 Here, the b * value is based on the field experiment on the slope in case of elastic wave velocity. It is recommended to use the average of the b * values that represent the range, and in the case of ultrasonic velocity, the minimum b * value should be used because it is based on rock samples without cracks. Since the above empirical formula is due to the accumulation of the experimental results, it is naturally desirable to further improve the reliability of the empirical formula by further accumulation, but in the case of evaluation, strict ultrasonic velocity and elasticity It is also necessary to consider that the wave velocity is not indispensable and that results can be obtained quickly and simply with an accuracy that does not hinder the evaluation. In that sense, it is preferable from the viewpoint of practical application to utilize such empirical formulas to accumulate experiments and improve accuracy. Ultrasonic velocity V obtained from the above empirical formula
_{From 1} and the elastic wave velocity V ₂ , the Kiretsu coefficient Cr is calculated by the following formula (S112). Cr = 1− (V ₂ / V ₁ ) ² Then, based on the average gradient data of each group calculated in S105 and the Kiretsu coefficient Cr, the stability of each group is obtained from the evaluation data relating to the relationship diagrams shown in FIGS. 10 and 11. And the stability of the entire rock slope S is evaluated.

By performing the evaluation in the above flow,
The evaluation work that required at least 5 days for field surveys, sampling surveys, and its analysis, can now be evaluated in almost one day. In addition, with regard to the evaluation results, almost the same evaluation could be obtained as compared with the evaluation methods used so far.

[0015]

EFFECTS OF THE INVENTION By using the rock slope stability evaluation method according to the present invention, the rock slope itself is first measured, so the labor, time and cost required for analysis of a rock sample, etc. can be reduced. Since no work is required, there is no problem in terms of safety. Further, by analyzing the data from each measuring means by the analysis device, the evaluation can be performed quickly, and the data analysis is automatically processed, so that the evaluation work can be easily carried out. As an evaluation method, assuming that the rock slopes are not uniform, the rock slopes are divided into groups for evaluation, and the grouping is performed based on the difference in the surface temperature of the slopes and the change over time. By relatively dividing the rock mass into parts having similar physical characteristics, the rock slope can be divided into parts having similar surface characteristics. Then, the reliability of grouping is ensured by looking at the correlation between the temperature change rate and the b * value for each group. That is, regarding the group having a negative correlation between the temperature change rate and the b * value, assuming that the reliability of the data is ensured, the elastic wave velocity and the ultrasonic wave are calculated from the empirical formula based on the b * value. Figure out the approximate value of each group from the approximate value of each group and the slope data.
The rock slope stability can be evaluated based on the relationship diagrams shown in 10 and FIG. As described above, the temperature change rate and b *
By combining the values, the reliability of the data can be ensured from a physical and material standpoint, and more detailed evaluation can be obtained by performing detailed evaluation for each part with the rock slope as a surface.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a rock slope stability evaluation device according to the present invention.

FIG. 2 is a flowchart showing an embodiment of a rock slope stability evaluation method according to the present invention.

FIG. 3 is a schematic diagram showing an example of a rock slope to be evaluated.

FIG. 4 is a state diagram when the rock slopes shown in FIG. 3 are grouped.

FIG. 5 is a graph showing changes in surface temperature with time at a plurality of measurement points on a rock slope.

FIG. 6 is a graph showing the correlation between temperature change rate and various parameters of b * value.

FIG. 7 is a graph showing the correlation between the temperature change rate and the b * value.

FIG. 8 is a graph showing the correlation between ultrasonic velocity and b * value.

FIG. 9 is a graph showing the correlation between elastic wave velocity and b * value.

FIG. 10 is a relational diagram showing the stability of a rock slope based on gradient data and elastic wave velocity.

FIG. 11 is a relationship diagram showing the stability of rock slopes based on slope data and Kiretsu coefficient.

[Explanation of symbols]

1 control unit 2 memory section 3 Output section 4 Input section 5 Lightwave rangefinder 6 Spectroradiometer 7 Thermal infrared imaging device S rock slope W forest P grassland

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keiichi Sugimoto 2-12-1, Kitano, Kanazu-cho, Fukui Prefecture (72) Inventor Shoji Okajima 23-1, Maguri, Shimizu-cho, Nyu-gun, Fukui Prefecture (72) Inventor Yuko Domae 1-153 Matsukawa, Maruoka-machi, Sakai-gun, Fukui Prefecture (56) Reference JP-A-2003-35691 (JP, A) Patent 3474515 (JP, B2) Patent 2867333 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01D 21/00 G01N 33/24

Claims (2)

(57) [Claims] 1. A rock slope stability evaluation method for evaluating the stability of a rock slope based on the slope data of rock mass, elastic wave velocity and ultrasonic velocity, the slope according to the following steps (a) to (g): A rock slope stability evaluation method comprising measuring data and calculating approximate values of elastic wave velocity and ultrasonic wave velocity to evaluate the stability of the rock slope. (A) Measuring the temperature distribution of the rock slope surface and its change over time (b) Grouping the slope surface into groups based on the data of the temperature distribution and its change over time (c) Measuring the average slope of each group, Obtaining the slope data of the group (d) The reflection spectrum of each group is measured, and b * concerning the Lab color system of each group is measured based on the measured data.
Calculate the value (e) Analyze the correlation between the rate of temperature change and b * value of each group and approximate the elastic wave velocity and ultrasonic velocity of that group from the b * value for the group with a negative correlation Calculate the value 2. A temperature data measuring means for measuring the temperature distribution on the rock slope surface and its change over time, an optical data measuring means for measuring the reflection spectrum of the rock slope surface, and a gradient for measuring the three-dimensional coordinates of the rock slope surface. A rock slope stability evaluation device comprising a data measuring device and a data analyzing device, wherein the data analyzing device groups slope surfaces based on a temperature distribution obtained from the temperature data measuring device and a temporal change pattern thereof. A means for dividing, a means for calculating the average gradient data of each group based on the data obtained from the gradient data measuring means, and a Lab color system of each group based on the reflection spectrum data obtained from the optical data measuring means Based on the temperature distribution obtained from the means for calculating the b * value of the Means for calculating a degree change rate,
A means to analyze the correlation between the temperature change rate of each group and the b * value and extract a group with a negative correlation, and an approximate value of the elastic wave velocity and the ultrasonic velocity based on the b * value of the extracted group. A rock slope stability evaluation device comprising: a means for calculating and a means for evaluating the stable state of the rock slope based on the extracted average gradient data of the group, the elastic wave velocity, and the approximate value of the ultrasonic velocity.