JP2019190254A - Estimation columnar diagram creation method by microtremor measurement, and program - Google Patents

Abstract

To provide a ground investigation method which compensates or replaces a conventional ground investigation method, and can be implemented with space saving, low noise and low cost in short time.SOLUTION: An estimation columnar diagram creation method includes: an Hfi/Vfi ratio calculation step of calculating an Hfi/Vfi ratio obtained by dividing a Fourier amplitude Hfi corresponding to a period Ti (i=1,2,3,...n (the number of layers)) of a horizontal component of microtremor of a ground measured with one microtremor measurement sensor by a Fourier amplitude Vfi corresponding to the period Ti of a vertical component of microtremor, at an arbitrary measurement point of the ground surface; and an estimation columnar diagram creation step of determining an Ni value in a depth Hi from a relationship between the period Ti and the depth Hi from the ground surface and a relationship between the Hfi/Vfi ratio and the Ni value, and creating an estimation columnar diagram at the measurement point.SELECTED DRAWING: Figure 2

Description

      The present invention relates to a method and a program for creating a columnar diagram in a short time from space-saving, low-noise, low-cost and short-time measurement results of ground.

      With the revision of the Building Standards Act in 2000, the ultimate strength calculation method was introduced in the seismic design of buildings, making it possible to design seismic designs for buildings that are out of specification, such as traditional wooden houses. Since this critical strength calculation method uses the ground of the construction site and the natural period of the building, it is necessary to investigate the vibration characteristics of the ground by a standard penetration test. As a ground survey conducted at the detached house level, the Swedish penetration test is common, but it is difficult to grasp the vibration characteristics of the ground, and the standard penetration test has problems of labor and cost. Therefore, a method of estimating the ground structure by measuring the natural period of the construction site by microtremor measurement, which is an economical simple exploration method, determining the ground type necessary for the seismic design, and analyzing the data can be considered.

      Conventional ground survey methods are specified in the structural technical standard manual for buildings, and include boring surveys, standard penetration tests, static penetration tests, page tests, soil tests, and physical exploration. The microtremor measurement method belongs to physical exploration among these. In addition to these ground surveys, ground surveys for buildings can be carried out using the methods used to determine the type of ground specified in the table of Article 93 of the Ordinance and survey methods widely used in the international and civil engineering fields. If there is a proven track record, confirm that the conversion from the test results to the various coefficients and ground constants used in the notification is appropriate, based on a comparison between the conventional ground survey and the test method. And can be used. In particular, in the field of detached houses, survey methods such as surface wave exploration and dynamic penetration tests, which are types of geophysical exploration, have been adopted for the purpose of confirming the pile support layer and understanding the stratum structure of residential land (Platinum). 13 Country Notification No. 1113, Last Revised July 21, 2005 Ministry of Land, Infrastructure, Transport and Tourism Notification No. 690).

      As a technique related to the present invention, for example, the ground survey method described in Patent Document 1 collects boring survey data of a plurality of boring points in the vicinity of a building, and the ground surface of the plurality of boring points corresponding to the survey data. It is characterized in that the surface wave spectrum for design of a building is obtained by calculating the wave spectrum and connecting and synthesizing the data on the larger side of the surface wave spectrum of each place.

      In addition, the ground velocity structure estimation method described in Patent Document 2 includes an estimation system including a plurality of vibration sensors and an analysis device for analyzing the output of the vibration sensor at a survey site, and from the dispersion characteristics of Rayleigh waves. It is a method for estimating the velocity structure of the ground by an inversion method, using the data up to the depth at which the data of the ground database in the vicinity of the survey site exists, and between the depth and the desired base layer, A model in which the S wave velocity and the number of layers are divided into a plurality of parts is added, and the ground structure is estimated by obtaining dispersion characteristics from the model.

      In addition, the ground velocity structure estimation method described in Patent Document 3 uses a microtremor observation device having a plurality of vibration sensors at a survey destination, and sets a reference velocity model as an initial value from its dispersion characteristics. It is a method of estimating the ground velocity structure by inverse analysis, calculating a plurality of theoretical dominant periods from a plurality of ground data around the survey destination, and measuring the observation dominant periods measured at the survey destination and the plurality of theoretical superiority Select the ground data with the theoretical dominant period that is most approximated by comparing with the period, perform reverse analysis using the selected ground data as a reference speed model, and estimate the ground speed structure of the survey destination It is characterized by.

      Furthermore, the ground structure estimation method described in Patent Document 4 includes a first step of calculating observation dispersion characteristics from microtremor observation by Rayleigh waves at a survey target point, and a ground database from the ground database near the survey target point. The second step of calculating the S wave velocity to create the S wave velocity structure of the database model and calculating the theoretical dispersion characteristic, and the theoretical dispersion characteristic of the S wave velocity structure calculated in the second step is the observation. A reference model is created by converting the S wave velocity until the phase velocity of the dispersion characteristic is approximated, and a reference dispersion characteristic is calculated, and the S wave velocity structure of the reference model obtained in the third step is used. And a fourth step of estimating the ground structure of the survey target point based on the fourth step.

JP 2002-250027 A JP 2001-311781 A JP 2001-193046 A JP 2001-091657 A

      The method described in Patent Document 1 needs to collect boring data at a plurality of points in the vicinity of the building. In addition, the methods described in Patent Document 2 and Patent Document 3 require a plurality of vibration sensors to be installed at and around the survey destination. There was no description or suggestion regarding the characteristic configuration of the present invention in which boring data is not used and one point observation is sufficient.

      In addition, the methods described in Patent Document 1 to Patent Document 4 are merely for the purpose of estimating the velocity structure of the ground, and are not intended for estimating the columnar diagram.

      Patent Documents 1 to 4 describe the relationship between the period Ti and the depth Hi from the ground surface, and the relationship between the horizontal and vertical Fourier amplitude ratios Hfi / Vfi and the Ni value. There has been no description or suggestion regarding the characteristic configuration of the present invention to estimate the Ni value in Hi.

      Furthermore, Patent Document 1 discloses a characteristic configuration of the present invention in which the depth to the engineering base is obtained by comparing the natural period of the ground calculated using a theoretical formula with the dominant period obtained by continuous microtremor measurement. Was not described or suggested.

      Therefore, an object of the present invention is to provide a ground investigation method that can be carried out in a short time, in a space-saving manner, with low noise, at low cost, that complements or replaces a conventional ground investigation method.

      In order to solve the above-described problem, the estimated columnar diagram creation method according to claim 1 is the periodic component period Ti (i) of the ground microtremor measured by one microtremor measurement sensor at any measurement point on the ground surface. = 1, 2, 3,... N (number of layers)) is calculated by dividing the Hfi / Vfi ratio by dividing the Fourier amplitude Hfi corresponding to the period Ti of the vertical component of the fine movement by the Fourier amplitude Vfi. The Ni value at the depth Hi is obtained from the Hfi / Vfi ratio calculating step, the relationship between the period Ti and the depth Hi from the ground surface, and the relationship between the Hfi / Vfi ratio and the Ni value, and the measurement An estimated columnar diagram creating step of creating an estimated columnar diagram at the point.

      The natural period of the ground is affected by the depth and hardness of the formation up to the engineering base. The deeper the formation up to the base, the longer the natural period. The harder the formation, the shorter the natural period and the smaller the amplitude. Therefore, it is considered that the analysis figure of the spectrum ratio and natural period of microtremors shows the ground structure as a fractal, and the magnitude of the amplitude is estimated to be similar to the hardness of the ground and the natural period is similar to the depth of the formation. The Based on this idea, the prevailing period of the ground and the Ni value and depth Hi of the formation are read from the measured spectrum analysis map of microtremors, and an estimated columnar diagram is created.

      In the present invention, the depth Hi (m) of an arbitrary i layer is estimated from the period Ti (sec) by microtremor measurement, and Hfi = √ (Hfxi × Hfyi) from the Fourier amplitude of two components in the horizontal x and y directions in the period Ti. ) The Ni value of the depth Hi layer is estimated from the ratio Hfi / Vfi of Hfi (cm / sec) obtained by the equation (1) and the Fourier amplitude Vfi (cm / sec) of one component in the vertical direction.

      Next, the estimated columnar diagram creation method according to claim 2 is the estimated columnar diagram creation method according to claim 1, wherein the relationship between the period Ti and the depth Hi, or the relationship between the Hfi / Vfi ratio and the Ni value. However, it is characterized in that it is obtained in advance by identification using a microtremor measurement value at a point other than the measurement point and an existing boring column diagram. In addition, points other than the said measurement point can be made into the point 1 km or more away from the said measurement point.

In the present invention, a graph in which the horizontal axis is the period Ti and the vertical axis is Hfi / Vfi rotated 90 degrees clockwise corresponds to a columnar diagram in which the vertical axis is the depth Hi and the horizontal axis is the Ni value. Thus (Table 1), the relationship between the period Ti and the depth Hi from the ground surface, and the relationship between the Hfi / Vfi ratio and the Ni value are obtained. The figure below shows that when the H / V spectrum (relationship between H / V and period) is rotated 90 degrees, the period T resembles a boring columnar diagram with depth H and H / V N values. Yes.

      A method for obtaining the relationship between the period Ti and the depth Hi will be described. First, the ground period Tg (sec) is obtained from this equation based on actual boring data. Next, the tendency of the numerical value is read by comparing the Tg obtained by the depth of the boring data and the depth of each layer, the natural period of the actually measured value, the Ni value of the boring data and the numerical value of Hfi / Vfi. In addition, the calculated value for obtaining Tg from the used boring data also takes into account the soil coefficient. In order to further improve the accuracy, Hi (thickness of the i layer) is cut to a constant thickness, and it is assumed that there are n (number of layers) of the thickness and identification with the boring data is attempted.

      The depth often does not match. This is because the drilling does not necessarily penetrate to the base, but may stop at the plus alpha that is expected to hit the pile. In addition, old data is often dug up or filled afterwards, and the GL position where the fine movement measurement is always performed is often different. Alternatively, a mismatch at the horizontal distance may result in a data mismatch. The relationship between the natural period Ti, depth Hi, Hfi / Vfi, and Ni value determined through trial and error is shown below.

      Case 1 is the relationship when sandy soil is dominant, and Case 2 is the relationship when viscous soil is dominant. However, in the actual ground, these are mixed. Finally, either Case 1 or Case 2 is adopted after identification. A section is provided in the graph so that the correlation coefficient of the relational expression derived from the data is 1.0 as much as possible, and a curve expression or a linear expression that is most approximated for each section is adopted.

The following graph shows the natural period including H (m) when the average geology with respect to T (sec) based on results is sandy soil, and includes an excerpt value (Table 5) of T (sec.) Described later, It is a correlation function with H (m) corresponding to it, and a graph (case 1).

The following graph shows H (m) when the average geology with respect to T (sec) based on actual results is cohesive soil, and includes a natural period including an excerpt value (Table 6) of T (sec.) Described later, and It is a correlation function and graph (Case 2) with corresponding H (m).

      In areas where the soil quality is greatly different, it may be necessary to modify the relationship between the natural period Ti and the depth Hi, Hfi / Vfi and the Ni value. In such a case, identification is performed again.

The estimated columnar diagram creation method according to claim 3, wherein the estimated columnar diagram creation method according to claim 3 includes the relationship between the cycle Ti and the depth Hi obtained by the identification method described above, wherein the cycle Ti (sec) and the cycle The relationship of the depth Hi (m) is expressed by the following (Equation 1) or (Equation 2).

Next, how to obtain the relationship between the Hfi / Vfi ratio and the Ni value will be described. First, the graph with the horizontal axis as the period Ti and the vertical axis as Hfi / Vfi is rotated 90 degrees clockwise so that the vertical axis corresponds to the columnar diagram with the depth Hi and the horizontal axis as the Ni value. Then, the identification is repeated and the relationship between the Hfi / Vfi ratio and the Ni value is obtained.
The following graph shows the correlation function between the H / V value based on the actual results and the H / V value including the H / V excerpt value described later and the corresponding N value.

The estimated columnar drawing creation method according to claim 4, which includes the relationship between the Hfi / Vfi ratio obtained by the identification method and the Ni value, and the estimated columnar drawing creation method according to claim 1, wherein the Hfi / Vfi ratio is The relationship between the Ni values is expressed by the following equation.

Within each range corresponding to (Equation 1), the natural period value (Ti) extracted from the relationship in H (m) (Case 1) when the average geology with respect to T (sec) based on the results is sandy soil Table 5 shows the results of obtaining Hi corresponding to (). In the table below, T (sec.) Is an excerpt of the approximate expression (Equation 1).

In each range corresponding to (Equation 2), the natural period value (Ti) extracted from the relationship in H (m) (Case 2) when the average geology with respect to T (sec) based on actual results is cohesive soil The results of obtaining (Hi) corresponding to are shown in (Table 6). In the table below, T (sec.) Is an excerpt of the approximate expression (Equation 2).

Table 7 shows the results of obtaining the Ni value corresponding to the extracted Hfi / Vfi from the relationship in the N value with respect to H / V based on the results within each range corresponding to (Equation 3). In the table below, H / V is an excerpt value.

      Next, an estimated columnar diagram creation method according to claim 5 is the estimated columnar diagram creation method according to any one of claims 1 to 4, wherein the ground dominant period Tgc calculated from a theoretical formula is The depth Hg from the ground surface to the rock mass is obtained by comparing with the dominant period Tgm obtained by measurement.

      Next, the program according to claim 6 is a program for calculating the horizontal component period Ti (i = 1, 2, 3,...) Of the ground fine movement measured by one fine movement measurement sensor at an arbitrary ground surface measurement point. An Hfi / Vfi ratio calculation process for calculating an Hfi / Vfi ratio obtained by dividing the Fourier amplitude Hfi corresponding to n (number of layers) by the Fourier amplitude Vfi corresponding to the period Ti of the vertical component of the fine movement; Estimating the Ni value at the depth Hi from the relationship between the period Ti and the depth Hi from the ground surface, and the relationship between the Hfi / Vfi ratio and the Ni value, and creating an estimated column diagram at the measurement point This is a program for causing a computer to execute columnar diagram creation processing.

      There are no restrictions on the measurement location because it uses a small noise-free and vibration-free measuring instrument. In addition, the measurement is performed on the ground surface, but it can also be measured on a dirt floor or on pavement. Furthermore, liquefaction and acceleration gain can be estimated with reference to geological maps near the measurement site, borehole data, and the like.

FIG. 1 is a block diagram illustrating an example of a measurement system configuration according to an embodiment of the present invention. FIG. 2 is an explanatory diagram illustrating an example of an operation scene according to the embodiment of the present invention. FIG. 3 shows an example of a flowchart 1 for identification using a microtremor measurement value of a program for causing a computer to execute the invention according to claim 6 and an existing boring column diagram (when it is not different from the boring column diagram). It is explanatory drawing. FIG. 4 shows an example of a flow chart 2 for identification using a microtremor measurement value of a program for causing a computer to execute the invention according to claim 6 and an existing boring columnar diagram (when different from the boring columnar diagram). It is explanatory drawing. FIG. 5 is an explanatory diagram (part 1) illustrating an example of a result of comparing the estimated columnar diagram and the boring columnar diagram. FIG. 6 is an explanatory diagram (part 2) illustrating an example of a result of comparing the estimated columnar diagram and the boring columnar diagram. FIG. 7 is an explanatory diagram (part 3) illustrating an example of a result obtained by comparing the estimated columnar diagram and the boring columnar diagram. FIG. 8 is an explanatory diagram (part 4) illustrating an example of a result of comparing the estimated columnar diagram and the depth of the bridge column base. FIG. 9 is a calculation form (clay layer, Onaga River Boring No. 1) for calculating the natural period from the boring data when the strata type is new. Fig. 10 shows a calculation form for calculating a natural period from existing boring data in the vicinity when the strata type is new (clay layer, Toga River boring old No. 1 (existing), height difference from new No. 1). 8 + 1.37 = 4.17). Fig. 11 shows the engineering base of the columnar figure in which the depth to the rock was added by calculation from the boring data of (Figure 9) and (Figure 10) above, the engineering base of the rock depth and the microtremor measurement results, the rock base depth It is an estimated columnar diagram created by identifying the height.

      Hereinafter, the present embodiment will be described. The embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, all the configurations described in the embodiments are not necessarily essential in the present invention. In addition, the content which overlaps with the description in the means for solving a subject, and the content regarding the well-known technique which a person skilled in the art can understand naturally are omitted as much as possible.

      FIG. 1 shows an example of a measurement system configuration according to an embodiment of the present invention. For microtremor measurement, a ground surface receiver (2-second meter) with a built-in AD converter for microtremor measurement was used. In combination with a notebook personal computer, it is possible to always measure fine movement. Note that the present invention is not limited to a notebook personal computer, and any form may be used as long as it can execute the processing of the present invention, such as a smartphone, a tablet terminal, or a desktop personal computer. It is also conceivable that the microtremor measuring instrument is provided with a function for executing the processing of the present invention. Furthermore, the processing of the present invention may be executed in a server via a network.

      FIG. 2 shows an example of an operation scene according to the embodiment of the present invention. Since the present invention can be implemented simply by installing one microtremor measurement sensor at a measurement point on an arbitrary ground surface, there is almost no place restriction. Although the microtremor measurement sensor and the notebook personal computer are connected by a cable, they can be integrated or processed by a server via a network in the future.

      The ground survey was performed by measuring the dominant period of the ground with a microtremor meter (speed meter with a natural period of 1 sec), judging the ground type and estimating the Ni value. The measurement was carried out three times with one measurement interval at one point as 100 seconds. The sampling frequency is 100 Hz, the observed components are three components, two horizontal motion components and one vertical motion component. A Fourier spectrum (smoothing: Parzen Window with a bandwidth of 0.4 Hz) of each 100-second observation record is calculated, and a horizontal dynamic Fourier spectrum is obtained by synthesizing two horizontal motion spectra. What was divided by the spectrum was displayed as an Hfi / Vfi spectrum.

The specific implementation procedure is as follows.
First, a moving coil speedometer for fine movement measurement is installed at the target site so that appropriate fine movement recording can be obtained. The installation location shall be at least 5 points on the same site. The measurement interval for one point is 100 seconds or more, and the measurement is carried out three times or more.

      Next, the sampling frequency in the measurement is 100 Hz, the observation components are 3 components of 2 horizontal motion components and 1 vertical motion component, and the Fourier spectrum of the observation record for each 100 seconds or longer (smoothing: Parzen Window with a bandwidth of 0.4 Hz). ) Is calculated, and a horizontal motion Fourier spectrum is obtained by spectrally synthesizing two horizontal motion components, and an H / V spectrum is obtained by dividing the horizontal motion Fourier spectrum by a vertical motion Fourier spectrum.

      Finally, the depth H corresponding to the natural period T is read from the spreadsheet software data of the H / V spectrum (H / V-T relationship) using the approximate expression (Equation 1) or (Equation 2). The N value corresponding to H / V is read using the approximate expression (3). A columnar diagram is created using the read depth H and N value data.

FIG. 3 shows an example of a flowchart 1 for identification using a microtremor measurement value of a program for causing a computer to execute the invention according to claim 6 and an existing boring column diagram (when it is not different from the boring column diagram). It is explanatory drawing.
1. In this flowchart 1, data collection has already been carried out at least 10 locations (survey locations in different regions) with the same estimated geology.
2. From time to time, there should be no major contradiction with the boring column. In cases 1 and 2 above, measurement and analysis are possible with this flowchart.
3. In addition, if there is a major contradiction in the depth of the engineering base of the boring column diagram in a new survey, identify it as a boring column diagram in Flowchart 2.

FIG. 4 shows an example of a flowchart 2 (when different from a boring column diagram) for identification using a microtremor measurement value of a program for causing a computer to execute the invention according to claim 6 and an existing boring column diagram. It is explanatory drawing.
1. This flowchart 2 shows that the depth of the engineering base is almost the same when the result analyzed by the method of the flowchart 1 has a large contradiction compared with the depth of the engineering base of the boring column diagram at the same place. Is corrected based on the extracted value (Table 5) of the approximate expression (Equation 1) or the extracted value (Table 6) of the approximate expression (Equation 2), and the extracted value (corrected (Table 5) or corrected) (Table 6)) and an approximate expression (corrected (Equation 1) or corrected (Equation 2)). (Hereafter, the extracted value (correction (Table 5)) or the extracted value (correction (Table 6)) and the approximate expression (correction (Expression 1)) or approximate expression (correction (Expression 2)).)
2. Or this flowchart 2 is the same place when there is no data collection with the same estimated geology as the measurement point, or when the data collection is less than 10 points (research points in different regions). Based on the excerpt value (Table 5) of the approximate expression (Equation 1) or the excerpt value (Table 6) of the approximate expression (Formula 2) so that the depth of the engineering base is almost the same as the borehole data at To make an excerpt value (correction (Table 5)) or excerpt value (correction (Table 6)) and an approximate expression (correction (Expression 1)) or approximate expression (correction (Expression 2)) Is the method.
3. Excerpt value (correction (Table 5)) or excerpt value (correction (Table 6)) and approximate expression (correction (Equation 1) so that it does not differ greatly from the engineering base depth of the boring column diagram at each point in the same place. )) Or an approximate expression (correction (Equation 2)). In the above cases 1, 2, and 3, measurement and analysis are possible with this flowchart 2.
4). In addition, (Equation 1), (Equation 2), (Table 5), and (Table 6) are created based on data obtained by performing measurement at 10 or more locations in the flowchart 1.

FIG. 5 to FIG. 7 are explanatory diagrams showing an example of a result of comparing the estimated columnar diagram created by using the present invention, the microtremor measurement value at a point other than the microtremor measurement point, and the existing boring columnar diagram. FIG. 8 is an explanatory diagram showing an example of the result of comparing the estimated columnar diagram created using the present invention with the bridge column base. In addition, the part shown by T shape in FIG. 5, FIG. 6 represents the depth of the pile constructed to the support ground. The part shown by the I shape of FIG. 8 represents the depth of the steel sheet pile constructed to the bedrock.
Fig. 5 shows the results of examination of pile support ground in Iwakuni city public facilities. FIG. 5 compares the boring columnar diagram with the estimated columnar diagram according to the present invention. The numerical values up to the supporting ground are approximated, and the supporting layer depth of the pile in the entire site was determined by the estimated columnar diagram according to the present invention.
Fig. 6 shows the results of examination of pile foundation support ground at Yamaguchi City High School. FIG. 6 is a comparison between the boring columnar diagram and the estimated columnar diagram of the present invention. In contrast to the boring columnar diagram where obstacles such as boulders are large, variation is difficult, and it is difficult to specify the position of the support layer, Since the average value of the variation due to the obstacle is expressed and the depth of the support layer is easy to specify, the depth of the support layer is determined according to the present invention in the practical design. As a result of the pile construction, it was confirmed that a strong support ground was obtained with the support layer according to the present invention.
FIG. 7 shows the result of examination according to the ground type. FIG. 7 compares the present invention for each ground type and the columnar diagram by boring. It can be seen that both Type 1 (Ube City Temple), Type 2 (Yamaguchi City High School), and Type 3 Ground (Hiroshima City Elementary School) are similar to a boring column diagram.
Figure 8 compares the steel sheet pile depth (in this case, rock) that was constructed after excavation of the column base at the Ube city bridge site and the estimated columnar diagram of the present invention obtained by measuring near the ground. It was confirmed that the depth to the bedrock was the same.
From the above results, it can be seen that according to the present invention, it is possible to perform high-precision estimation that cannot be conventionally performed with only one microtremor measurement sensor.

An embodiment in the case where the present invention is used for determining a pile position will be described.
The following figure shows a case where there was an obstacle during construction of a pile in a public facility in Sanyo Onoda city, and the depth position and size of the obstacle were estimated by the method of the present invention. As a result, as shown in the note in the figure, the depth position and size of the obstacle were estimated, and the pile position was changed accordingly, and the construction was completed.

Next, an embodiment when the present invention is used for ancient cave exploration will be described. As a result of investigating the location where EVs for elderly people are installed in a five-story apartment house in Ube City, the depth and position of an old cave by coal mining was discovered. Exploration was conducted. As a result, we were able to promptly propose an EV installation location and a pile foundation construction method considering the old caves.

      As a reference, Fig. 9 shows a calculation sheet (clay layer, Togagawa Boring New No. 1) for generating a natural period from the boring data (the ground GL after the same embankment as in the case of microtremor measurement) when the strata type is new. 1). In addition, in Fig. 10, when the stratum type is new, the calculation sheet (clay layer, Onaga River boring old No. 1 and new No. 1) that calculates the natural period from the old boring data (boring data before embankment) The height difference is 2.8 + 1.37 = 1.17 and the drilling data start depth is 0.7 m).

Finally, Fig. 11 shows an estimated column diagram created by identifying the depth of the columnar figure calculated from the borehole data when the strata type is new and adding the depth to the rock, and the depth of the microtremor measurement result. .
Fig. 11 shows the engineering base of the columnar figure which added the depth to the rock mass calculated from the borehole data of the above (Fig. 9) and (Fig. 10), the engineering foundation of the rock mass depth and the microtremor measurement result, It is an estimated columnar diagram created by identifying Sato. The graph on the left side of FIG. 1 (after embankment) and at the same time, almost the same time, is an estimated columnar figure by microtremor measured at a place. The graph on the right side of FIG. 1 (before embankment) and after embankment, it is an estimated columnar figure by microtremor measured at a location about 2 m away.

1 Measurer 2 Notebook personal computer 3 Cable 4 Microtremor measurement sensor

Claims (6)

    Corresponds to the horizontal component period Ti (i = 1, 2, 3,... N (number of layers)) of the ground microtremor measured by one microtremor measurement sensor at an arbitrary ground surface measurement point. An Hfi / Vfi ratio calculating step of calculating an Hfi / Vfi ratio by dividing the Fourier amplitude Hfi by the Fourier amplitude Vfi corresponding to the period Ti of the normal fine movement vertical component; the period Ti and the depth from the ground surface An estimated column diagram creating step of obtaining the Ni value at the depth Hi from the relationship of Hi and the relationship between the Hfi / Vfi ratio and the Ni value and creating an estimated column diagram at the measurement point. Estimated columnar drawing creation method.     The relationship between the period Ti and the depth Hi, or the relationship between the Hfi / Vfi ratio and the Ni value was obtained in advance by identification using a microtremor measurement value at a point other than the measurement point and an existing boring column diagram. The estimated columnar drawing creation method according to claim 1, wherein the method is a thing. The estimated columnar drawing creation method according to claim 1, wherein the relationship between the period Ti (sec) and the depth Hi (m) is expressed by the following (Equation 1) or (Equation 2).

The estimated columnar drawing creation method according to claim 1, wherein the relationship between the Hfi / Vfi ratio and the Ni value is expressed by the following equation.

    The depth Hg from the ground surface to the rock is determined by comparing the ground dominant period Tgc calculated from the theoretical formula with the dominant period Tgm obtained by continuous microtremor measurement. The estimated columnar drawing creation method according to claim 4.     Corresponds to the horizontal component period Ti (i = 1, 2, 3,... N (number of layers)) of the ground microtremor measured by one microtremor measurement sensor at an arbitrary ground surface measurement point. Hfi / Vfi ratio calculation processing for calculating an Hfi / Vfi ratio obtained by dividing the Fourier amplitude Hfi by the Fourier amplitude Vfi corresponding to the period Ti of the vertical component of the fine movement, and the depth from the period Ti and the ground surface Based on the relationship between Hi and the relationship between the Hfi / Vfi ratio and the Ni value, the Ni value at the depth Hi is obtained, and an estimated column diagram creation process for creating an estimated column diagram at the measurement point is executed by a computer. Program for.

Images