JP3307840B2 - Measurement method of seismic motion with seismograph - 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 for measuring seismic motion in a seismometer such as a control seismometer.

[0002]

2. Description of the Related Art In the event of an earthquake, there is a control seismometer as a device for controlling various systems according to the intensity of the earthquake to prevent the spread of damage and the occurrence of secondary disasters.
2. Description of the Related Art A control seismometer is used in various facilities such as transportation, city gas, electric power, and water supply by being incorporated in an automatic emergency stop device at the time of a large earthquake.

In such a control seismometer, a method of measuring the SI value as a measure of the intensity of earthquake motion has been proposed and implemented in order to perform control having a high correlation with the degree of damage to the structure. (For example, Japanese Patent Application Laid-Open No. 62-12884
JP, JP-A-62-12884, JP-A-62-12884
No. 12884, Japanese Patent Application Laid-Open No. Sho 62-12885, Japanese Patent Application Laid-Open No. Sho 62-12886, Japanese Patent Application Laid-Open No. 6-214040
See JP-A-8-36062 and JP-A-8-36062. )

In such a method, the SI value is obtained by inputting an acceleration waveform of a seismic motion measured by a seismograph into an arithmetic unit that satisfies the equation of motion of a one-degree-of-freedom vibration system, and obtaining a speed response every moment. Spectrum of the maximum value of
It is obtained by performing a predetermined calculation from the speed response spectrum Sv.

Usually, a seismometer has two orthogonal horizontal components,
For example, it is installed so as to measure the acceleration of the components in the north-south direction and the east-west direction, and is configured to calculate the SI value from the measured acceleration waveforms of the components in these directions.

[0006]

However, in an actual earthquake, the above-mentioned specific direction does not always vibrate so as to maximize the SI value. That is,
Since the SI value has a large angle dependency due to its nature, and the value differs greatly depending on the direction of the acceleration component measured by the seismometer, the SI value in that direction is calculated simply by using the acceleration waveform of the component in a specific direction. However, it cannot always be said that the maximum SI value can be calculated, and there is a possibility that an error may increase when evaluating damage due to an earthquake.

[0007] For example, FIG. 5 shows seismograph data from an actual earthquake (Nipponkai Chubu Earthquake (Tsugaru Ohashi)).
It shows an example of SI values calculated for all directions.
In the figure, the angle 0 ° corresponds to the north-south direction and 90 ° corresponds to the east-west direction, and the SI value output by the acceleration waveform measured in these directions is 43.2 [kine]. However, as shown in the figure, the SI value actually becomes the largest in the direction at an angle of about 45 °, and the SI value in this direction is 6 °.
7.1 [kine], which is about 1.5 from the above SI value output.
Five times larger.

[0008] Damage to the facility due to the earthquake does not depend on the direction of the vibration. Therefore, the SI value output of the north-south direction and the east-west direction vibration described above may underestimate the damage.

By the way, the magnitude and the direction of the instantaneous value of the maximum acceleration at each time point after the occurrence of the earthquake are determined by a simple vector synthesis of the north-south direction and the east-west direction acceleration as shown in FIG. The direction of the maximum acceleration changes momentarily depending on the ratio of the measured values in the x-axis direction (east-west direction) and the y-axis direction (north-south direction) in the figure, It is not always determined in one direction.

Therefore, even if the velocity response is obtained from the maximum acceleration sequentially obtained by such a simple vector synthesis and the SI value is obtained therefrom, integration for a discontinuous surface is performed. Makes no sense, after all,
Even with this method, the maximum SI value cannot be obtained.

The present invention has been made in view of the above points, and an object of the present invention is to make it possible to measure a ground motion component in a predetermined desired direction from a plurality of directional components of a ground motion measured by a seismometer. It is in.

[0012]

In order to solve the above-mentioned problems, according to the present invention, first, a detection signal of each of these multi-directional components of a seismometer installed to detect the multi-directional components of the seismic motion is provided. It is proposed to calculate a seismic motion component in a desired direction by performing vector synthesis in a desired direction set in advance , and to continuously measure the seismic motion component in the desired direction.

According to the present invention, in the above-described configuration, a desired horizontal seismic motion component can be continuously measured as two components in the horizontal direction to be detected.

According to the present invention, in the above configuration, the detected multi-directional components include two components in the horizontal direction and a component in the vertical direction, so that a three-dimensional earthquake motion component in a desired direction can be continuously measured.

According to the present invention, in the above configuration, the direction of the seismic motion component calculated by vector synthesis and continuously measured can be one direction or a plurality of directions.

According to the present invention described above, the detection signals of the plurality of components of the seismic motion are vector-synthesized,
Seismic motion components in desired directions other than the direction detected by the seismometer can be calculated and continuously measured.

Therefore, by comparing the seismic ground motion components in a plurality of directions continuously measured as described above, the component having the maximum ground motion intensity can be selected. Therefore, if the magnitude of the seismic intensity is the SI value, the maximum value of the SI value can be obtained regardless of the installation direction of the seismometer.

[0018]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram conceptually showing an example of a configuration for implementing a method of measuring an earthquake motion according to the present invention. First, the configuration of the solid line in the figure will be described. Reference numeral 1 denotes a seismometer, and reference numerals 2a and 2b denote detection units for detecting two orthogonal horizontal components. These detectors 2a, 2b
For example, they are installed so as to measure the acceleration of the components in the north-south direction and the east-west direction, respectively, as in the conventional case.

Reference numeral 3 denotes an arithmetic processing means. The arithmetic processing means 3 sets the acceleration signals of the north-south and east-west vibrations output from the detection sections 2a and 2b by vector synthesis as described later . This is a configuration for calculating an acceleration component in a desired direction. Then, the acceleration component in the desired direction obtained by the vector synthesis by the arithmetic processing means 3 is stored in the storage means 4 and used for the subsequent arithmetic processing and the like. In the illustrated example, the direction in which the acceleration component is calculated by vector synthesis is a direction obtained by dividing all directions into eight, that is, as shown in FIG.
2.5 ゜, 45 ゜, 67.5 ゜, 90 ゜, 112.5
{135, 157.5} in eight directions,
-5h indicate respective storage units. Note that θ = 0 ° and 9
Since the direction of 0 ° is the direction detected by the detection units 2a and 2b, vector synthesis is unnecessary.

FIG. 2 illustrates the principle of vector synthesis according to the present invention with respect to the directions of θ (= 22.5 °) and θ ′ (= 135 °). The x-axis is the east-west direction, and the y-axis is the north-south direction. It corresponds to the direction. In the figure, X and Y indicate accelerations detected by the detection units 2b and 2a at a certain time, respectively.
By projecting and adding these acceleration vectors in the θ direction, the acceleration of the component in the θ direction can be calculated. That is, assuming that the acceleration of the component in the θ direction is αθ, this αθ is calculated by an arithmetic expression of αθ = Xcosθ + Ysinθ. Similarly, the acceleration αθ of the component in the θ ′ direction is αθ ′
= Xcosθ '+ Ysinθ'. In this way, by performing the above-described calculation on the acceleration detected by the detection units 2b and 2a at a certain point in time in each of the preset directions, the acceleration of the component in each direction can be calculated. Is performed continuously at appropriate time intervals, thereby enabling continuous measurement of acceleration waveforms in desired directions, in this example, eight horizontal directions (including two directions requiring no calculation).

As described above, the acceleration components in the eight directions continuously measured as described above are supplied to the subsequent arithmetic processing and the like via the storage units 5a to 5h of the storage unit 4. This calculation processing includes processing for obtaining the maximum acceleration, processing for calculating the SI value in each direction to obtain the maximum SI value as described later, and the like.

Next, an example of the latter process, that is, the process of calculating the SI value in each direction and obtaining the maximum SI value, will be described with reference to the flowchart of FIG. I will explain. First, in step S1, the acceleration projection angle θ is initialized, that is, θ = 0. Next, in step S2, the time of the acceleration signal detected over time by the detector of the seismometer is initialized, that is, measurement is started with t = 0. Next, at step S3, at time t, each axis,
That is, the x-axis and y-axis accelerations are input. These acceleration signals are referred to as α _xt and α _yt , respectively. Next, in step S4, the above equation is calculated in the θ direction, and the time t,
to calculate the θ direction of the acceleration αθ _t. Next, step S5
In the acceleration Arufashita _t calculated in step S4, performs an operation that satisfies the equation of motion of one degree of freedom vibration system having a natural period omega, time t, theta direction, velocity response Sv natural period omega
Calculate θ _t ω. Next, in step S6, a velocity response spectrum is calculated, and in step S7,
If the current response is larger than the speed response calculated in the processing loop up to that time and stored as the maximum value, the current response is stored as the maximum value in step S7, that is, the maximum value is updated. If the previous one is larger, the next step S8 is performed without updating the maximum value.
Move to In step S8, the time is advanced by a predetermined time interval Δt, and as time t = t + Δt, step S8 is performed.
Then, in step S9, it is determined whether or not the earthquake has ended. If it is determined in step S9 that the earthquake has not ended, the process returns to step S3, and thereafter, the acceleration signal at time t (= t + Δt) is returned to step S3.
Steps S7 to S7 are repeatedly performed, and the maximum value of the speed response spectrum is updated. If it is determined in step S9 that the earthquake has ended, the process proceeds to step S10, where the SI value in the θ direction is calculated by the operation formula in the figure. After calculating the SI value in step S10 in this manner, the process proceeds to step S11,
In this step S11, the projection angle θ is set to a predetermined angle width Δ
The following step S12 is performed by adding θ only and setting θ = θ + Δθ.
Move to In step S12, the maximum SI value is calculated. That is, in step S13, the current SI value,
That is, if the current value is larger than SIθ and SImax calculated in the processing loop up to that time and stored as the maximum value, the maximum value is stored in step S13, that is, the maximum value is stored. In addition to the updating, if the previous one is larger, the process moves to the next step S14 without updating the maximum value. In step S14,
It is determined whether or not the above process has been completed for all directions. If it is determined that θ <180 °, that is, if it has been determined that the process has not been completed for all directions, the process returns to step S2 and returns to step S11. The above processing is repeatedly performed for the set projection angle θ. When the projection angle is set to θ = 180 ° in step S11, step S1
In step 4, it is determined that the above processes in all directions have been completed, and the series of processes ends. Then, at this end point, the maximum SI value stored in the processing of step S13, that is, SImax, can be obtained.

In the processing described above, the processing described above with reference to the configuration of FIG. 1, ie, after the acceleration components in each direction are calculated in advance by the arithmetic processing means 3, the subsequent processing is performed on these acceleration components. Unlike the ones, for each of the directions, following the calculation of the acceleration component,
The difference is that the subsequent processing such as SI value calculation is performed.
Specific procedures of these processes can be appropriately set in addition to the above.

Next, in addition to the above-described embodiments, the present invention can take the following forms, for example. a. The multi-directional component for detecting ground motion can be made into three components by adding a vertical component in addition to two horizontal components, and in this case, it is necessary to continuously measure three-dimensional ground motion components in a desired direction. Can be. The detection unit for detecting the component in the vertical direction is a detection unit 2c indicated by a two-dot chain line in FIG.
It is. b. The direction of the seismic motion component that is calculated and continuously measured by the vector synthesis is the above-described eight horizontal directions, and the number thereof can be appropriately increased or decreased. However, in this case, the calculated maximum value of the SI value has an advantage that the error from the SI value obtained as defined decreases, and conversely, if the maximum value of the SI value decreases, the error of the SI value becomes a certain value. Has the advantage that the resources and the time required for calculating the SI value can be reduced, while permitting. FIG. 4 shows 95% of the SI value obtained as defined when the number of directions to be measured is changed.
It shows the% confidence interval. c. The calculation of the seismic motion component in each direction can be performed by a single arithmetic processing unit or by performing a plurality of arithmetic processing units in parallel.

[0025]

As described above, according to the present invention, a seismic wave component in a desired direction set in advance can be measured from a plurality of directional components of a seismic wave measured by a seismometer. a. The minimum number of seismometer detectors can continuously measure ground motion in many directions. b. Therefore, it is possible to easily and reliably obtain the direction of the seismic intensity, for example, the maximum value of the SI value. Therefore, underestimation of the damage caused by the earthquake can be prevented.

[Brief description of the drawings]

FIG. 1 is a system diagram conceptually showing an example of a configuration for implementing a method for measuring a seismic motion according to the present invention.

FIG. 2 shows the principle of vector synthesis according to the present invention as θ (=
FIG. 2 is a vector diagram illustrating directions of 22.5 °) and θ ′ (= 135 °).

FIG. 3 is a flowchart showing an example of an overall processing flow of the present invention including processing of calculating an SI value in each direction and obtaining a maximum SI value.

FIG. 4 is an explanatory diagram showing 95% confidence intervals for SI values obtained as defined when the number of directions to be measured is changed.

FIG. 5 is an explanatory diagram showing an example of SI values calculated in all directions from seismograph data of an actually occurred earthquake (Chubu-Japan Sea Earthquake (Tsugaru Ohashi)).

FIG. 6 is a vector diagram showing simple vector synthesis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Seismometer 2a, 2b detection part 3 Operation processing means 4 Storage means 5a-5h storage part

Continuation of the front page (72) Inventor Hikaru Takubo 2-12-19 Shibuya, Shibuya-ku, Tokyo Yamatake Honeywell Co., Ltd. Head Office (56) References JP-A-62-128484 (JP, A) JP-A-62-1886 (JP, A) JP-A-6-214040 (JP, A) JP-A-8-36062 (JP, A) JP-A-63-121718 (JP, A) JP-A-6-313729 (JP, A) Kaihei 2-302687 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01V 1/28 G01H 1/00 G01V 1/16

Claims (4)

(57) [Claims] 1. A seismometer installed so as to detect a plurality of directional components of a seismic motion, and a detection signal of each of the plurality of directional components is vector-synthesized in a predetermined desired direction to calculate a seismic motion component in a desired direction. And measuring the seismic motion component in the desired direction continuously. 2. The method for measuring seismic motion in a seismometer according to claim 1, wherein the detected multi-directional components are two horizontal components, and a desired horizontal seismic motion component is continuously measured. 3. The seismometer according to claim 1, wherein the detected multi-directional components are two horizontal components and a vertical component, and a three-dimensional seismic motion component in a desired direction is continuously measured. Measurement method. 4. The seismometer according to claim 1, wherein the direction of the seismic motion component calculated by vector synthesis and continuously measured is a plurality of directions. Measurement method.