JP4293453B2 - Dam disaster prevention method and equipment by earthquake early warning - Google Patents

Description

  It relates to dam earthquake prevention technology based on observation data from the national seismic network.

  Summarizing the damage modes of existing dams during earthquakes, the phenomenon of cracking occurs in concrete dams, and the phenomenon of subsidence and residual deformation occurs in fill dams. In order to accurately evaluate the seismic performance of dams in the past, analysis of earthquake damage that occurred in the past clarifies the dam damage process and damage mode when subjected to extremely strong ground motions, such as cracks and residual deformation. It is necessary to quantitatively evaluate the amount of damage. If earthquake damage is expected, it is important to check that the water storage function of the dam is maintained safely and there is no risk of a secondary disaster even if earthquake damage occurs. It suggests.

JP 2003-114281 A Japan Society of Civil Engineers Real-time disaster information detection and its use symposium (June 2004), pp125-130

  As for dam disaster prevention methods and equipment based on observation data from the national seismic observation network, an immediate evaluation method for dam earthquake damage has been proposed, and verification tests have been conducted.

Japanese Patent Application No. 2001-308218 Japan Society of Civil Engineers Real-time disaster information detection and its use symposium (June 2004), pp125-130

The problems to be solved by the invention are summarized below.
1． Seismic disaster prevention for dams Hydroelectric energy is purely domestic non-polluting natural energy, and is a valuable base power source in Japan from the viewpoint of global environmental conservation. There is a dam as one of the large structures that make up a hydroelectric power plant. The dam is a highly social facility, and it is a very important technical matter to confirm and ensure safety during an earthquake. The dam is a structure with excellent earthquake resistance. However, looking at examples of earthquake experiences in the world so far, there have been several reports of cases of damage caused by major earthquakes, and there are residents living in the vicinity. The damage caused by the damage in the area is serious. Therefore, it is important to be prepared for earthquake disaster prevention with special attention.

  When an earthquake occurs, the current situation is that the first occurrence of an earthquake is known to occur, and the degree of seismic intensity has been confirmed after the shaking has stopped. It is common to check the safety by implementing it. With the advancement of earthquake disaster prevention technology, it will be possible to know the occurrence of earthquakes before the arrival of earthquake motion, and to understand the necessity of temporary inspection and the parts that should be preferentially checked before the arrival of earthquake motion. .

  In recent years, high-sensitivity seismic networks (Hi-net), strong-motion seismic networks (K-NET, KiK-net), etc. have been developed with high density so that earthquake information can be collected, analyzed, and utilized quickly. It is becoming. Technology has been developed to identify hypocenter information in about 3-4 seconds after detecting the initial tremor (P wave) of the earthquake. It is becoming possible to deliver an emergency earthquake warning that “the number of seismic intensity will reach later”.

  In addition, in existing dams, seismic observations are carried out in major existing dams in order to use them for dam safety management and higher accuracy of seismic design technology, and effective use of seismic observation data obtained from existing dams is also possible. Has been done.

  The social demand for dam safety during earthquakes is thought to change according to national conditions such as natural conditions and social conditions, but it is located in the Pacific Rim earthquake zone where the four plates collide in a complicated manner, and the land area is small. In Japan, where the area of inhabitable land is small and land use in river basins has advanced at a high density, social demands regarding the seismic performance and disaster prevention performance of dams are high. The use of emergency earthquake bulletins is considered to be very effective in improving the earthquake disaster prevention performance of dams and the surrounding areas of dams. It is necessary to examine the device for this and the applicability to electric power facilities.

2. 3D dynamic analysis technology On the other hand, along with the improvement in performance of computer equipment, 3D dynamic analysis technology for dam-foundation bedrock-reservoir coupled system has been put into practical use. A review of seismic performance is becoming possible.

  Based on this background, it is desirable to have a method for immediately evaluating and judging the safety of existing dams during earthquakes by organically linking emergency earthquake warnings, earthquake observation information at existing dams, and 3D dynamic analysis technology. It is. In addition, by using a high-performance supercomputer, it is possible to perform a three-dimensional dynamic analysis of a dam in real time after receiving an earthquake early warning.

  However, when using an ordinary computer at present, a long time is required for the three-dimensional dynamic analysis of the dam. In practice, it is difficult to immediately respond to the response, so a preliminary analysis is performed.

  Therefore, as usual preparations, 3D dynamic analysis with various analysis conditions related to input ground motion, foundation rock, reservoir, etc. is performed in advance, and global earthquake damage cases and 3D dynamic analysis results are consolidated. By systematizing it, it is possible to immediately predict dam damage in the event of a major earthquake and to respond in real time in an emergency.

3. Regarding damage analysis of dams Dams are considered to have high seismic resistance against earthquake motions, so they are very rarely damaged structurally, although they may suffer minor damage during an earthquake. It is believed that there is. However, there have been reports of cases of severe earthquake damage in existing dams around the world. For this reason, it is important to check the safety of dams during earthquakes so that they can be confirmed smoothly and quickly in the event of a major earthquake. In dams, it is stipulated that extraordinary inspections are carried out when the seismic intensity is 4 or higher. Therefore, it is effective to use emergency earthquake warnings as temporary inspection information when seismic intensity 4 or higher is assumed.
(1) In the previous studies using arch-type concrete dams, there is an analysis to predict damage due to tensile failure.
(2) In the case of Malpassedam (France) in December 1959, the dam collapse was caused by the collapse of the foundation rock. In the damage analysis, in order to consider the collapse of the surrounding rock mass, it is necessary to study with a wider range of models.
(3) It is necessary to pay attention to the expression of the calculation results, such as the distribution of stress generated in the concrete calculated by the continuum model is not necessarily the dam damage form itself.

(4) About application to fill dam
(4-1) Regarding the concrete dam, the ground is good and there is very little earthquake damage. Based on past earthquake damage, the fill dam (especially the earth dam) is considered to be an important target. If the ground is bad, the risk of earthquake damage will increase. There have been reports of significant earthquake damages such as liquefaction in ponds. In addition, with the progress of urbanization in recent years, the area that has been urbanized to just below the dam is also increasing.

(5) Applicability of earthquake damage prediction for dam facilities
(5-1) Modern dams in Japan are extremely strong, and damage to the dam itself during an earthquake is unlikely. However, there are many old dams built before 1958, and the effects on surrounding facilities were examined. It is necessary to consider expanding the application to
(5-2) Safety measures by using early earthquake warnings are effective because of the activity of faults that are not on the surface of the earth, such as the major damage of dams caused by the Taiwan earthquake (September 21, 1999). is important.
(5-3) With regard to the stability of incidental facilities during earthquakes, not only the immediate vicinity of the dam, but also the surrounding rock masses and the possibility of damage due to slope failure around the reservoir, the scope of risk assessment will be expanded. It will be necessary.

4). Issues such as standardization to promote dissemination
(1) Since dams have different shapes, surrounding topography, and geology, analysis according to each point is required. Since the safety of the dam depends greatly on the geology of the site, analysis in consideration of the characteristics of each point is necessary.
(2) Standardization is necessary from the viewpoint of cost reduction and diffusion of the entire system. It is conceivable to consider patterning that focuses on the dam type, shape, and dynamic characteristics of the ground (main S wave velocity).
(3) It is important to use software measures to confirm the safety of the dam when an earthquake that greatly exceeds the assumptions made at the time of design occurs and to improve the earthquake disaster prevention at the dam site. Even if the structure is designed for strong ground motion, there are technical and cost limitations, and software measures are necessary to compensate for the limitations of such hardware measures.
In addition, it is necessary to study a method for immediately predicting and evaluating the damage of existing dams during earthquakes immediately before or after the arrival of earthquake motion using the emergency earthquake bulletin delivered by the Japan Meteorological Agency. As for dams, it is stipulated that a temporary inspection should be carried out if an earthquake with a seismic intensity of 4 or more occurs, so it is very close to making daily inspections more efficient, useful for disaster drills and education. It becomes the purpose.

5. Information transmission
(1) In Japan, there are about 2800 large dams with a height of 15m or more nationwide. There are 250,000 to 300,000 earth fill dams with a height of 15m or less, and it is possible to effectively use emergency earthquake warnings. However, dissemination is difficult if the cost of data usage fees is high. Although it is appropriate that some usage fee is charged from the viewpoint of burden on the receiver, an explanation that understands the significance is necessary.
(2) The means for transmitting the earthquake early warning is based on the premise that information distributed from the Japan Meteorological Agency, etc. is transmitted from the Real-time Earthquake Information Utilization Council (hereinafter referred to as REIC) via a dedicated line, satellite line, or the like.
(3) At dams, seismic observations have been carried out continuously since the Showa 30s. Since the Hyogoken-Nanbu Earthquake, the number of dams for which seismic observations have been carried out has increased. There is a possibility of mutual use with data.
(4) The provision of information to the outside is required to be highly accurate information because of its great influence. For this reason, it is effective not to use a probabilistic method, but to identify the source and site and predict damage individually by seismic response analysis.
(5) It is necessary to establish a management system that uses earthquake early warning in order to prevent the entire system including related facilities, not just the dam body.
(6) When distributing information, it is necessary to make the information more reliable by improving the accuracy of earthquake motion estimation and damage prediction analysis.

The present invention, as a dam disaster prevention method based on the earthquake early warning, estimates the earthquake motion assumed at the dam site from the location and magnitude of the earthquake early warning distributed before the arrival of the earthquake motion, and is assumed at the estimated dam site. Dam site damage is predicted by three-dimensional dynamic analysis based on physical properties related to seismic ground motion, foundation bedrock, and reservoir, and the risk of secondary disaster is predicted from the predicted dam site damage. The dam site damage and the risk of secondary disaster are delivered together with the earthquake early warning.
In addition, as a dam disaster prevention device based on the earthquake early warning, the dam site ground motion estimation means for estimating the ground motion assumed at the dam site from the location and magnitude of the earthquake early warning distributed before the arrival of the ground motion, and the dam site ground motion estimation Damage prediction means for predicting damage to the dam site by three-dimensional dynamic analysis based on the physical properties of the dam site estimated by the means based on the ground motion, foundation rock mass and reservoir, and the dam predicted by the damage prediction means Secondary disaster prediction means for predicting the risk of secondary disaster from site damage, damage to the dam site predicted by the damage prediction means, and risk of secondary disaster predicted by the secondary disaster prediction means Disaster prevention information distribution means for distributing information together with the earthquake early warning is provided.

Hereinafter, the effect by the dam disaster prevention method and apparatus by the earthquake early warning concerning this invention is demonstrated for every item of a subject, and a claim.
2. Three-dimensional dynamic analysis technology By integrating the system of global earthquake damage cases and the results of three-dimensional dynamic analysis, dam damage in the event of a large earthquake can be predicted immediately and real-time response is possible I made it.
3. About dam damage analysis In order to predict the damage mode of an existing dam at the time of earthquake, the dam damage analysis is incorporated into the system by incorporating an evaluation process called seismic damage analysis of the ground-structure system necessary for damage prediction during an earthquake. Earthquake disaster prevention is possible.

5. Regarding the information transmission, before the shaking caused by the earthquake arrives, the person in charge of the control center can operate the appropriate control measures and provide immediate earthquake disaster prevention information to citizens, electric utilities, river managers, etc. in the surrounding area. By making a transmission, it is possible to notify related parties and prevent human and property damage.
(1) Features of the system of the present invention One of the features of the dam disaster prevention system is that it incorporates the combined use technology of geosphere information (GIS, satellite images, etc.) into the system in order to visualize earthquake disaster prevention information. It is. These functions can be applied not only to dam sites, but also to a wide variety of facilities and structures, and widely throughout the country regardless of mountainous or urban areas.
(2) Personnel application Earthquake early warning is highly effective for human resources such as education, and it can be used more effectively by providing education on the premise of transmitting safety information and overflow information to neighboring residents. Become.
(3) Regarding the form of dissemination of results regarding the applicability of the dissemination system to the field, the case of distributing only earthquake information according to the situation of human resources and physical resources on the user side (mobile phone, personal computer, alarm, Broadcasting, etc.), cases of providing as a system including hardware and software, cases of consulting for analysis evaluation such as damage prediction, etc., there are individual and multiple combinations.

And the effect obtained by the dam disaster prevention method and apparatus by the earthquake early warning according to the present invention is provided with the disaster prevention information distribution means as the means for transmitting the emergency earthquake early warning, so that the personnel concerned and physical damage are reported. It becomes possible to prevent it in advance. In addition, dam site seismic motion estimation means, damage prediction means, and secondary disaster prediction means enable accurate earthquake disaster prevention of dams. Real time response is possible.

  The following Examples 1-4 will explain a dam disaster prevention method and apparatus based on the earthquake early warning according to the present invention.

  First, the basic concept of the dam disaster prevention method and apparatus based on the earthquake early warning according to the present invention will be described.

  FIG. 1 is a diagram showing a basic procedure for immediate evaluation of a dam disaster prevention method and apparatus based on an earthquake early warning according to the present invention. As shown in FIG. 1, the basic procedure for immediate evaluation is largely divided into (a) a preliminary evaluation stage for performing an immediate evaluation, and (b) an immediate evaluation stage at the time of occurrence of an earthquake. Comprised of two stages. The former (a) is an analysis of earthquake experience cases of existing dams in the world (Step S1), three-dimensional dynamic analysis with various conditions (Step S2), and preparation of earthquake damage charts for assumed earthquake motion (Step S3) ). The latter (b) is the estimation of the ground motion of the dam site to be evaluated based on the earthquake early warning (Step S5), the immediate evaluation based on the earthquake damage chart that summarizes the 3D dynamic analysis results (Step S6), and the maintenance site It is comprised by the information transmission to (step S7).

Hereinafter, Example 1 of the present invention will be described for each elemental technology.
(1) Utilization of Earthquake Early Warning FIG. 2 is a diagram showing a basic procedure for immediate evaluation of the dam disaster prevention method and apparatus by the earthquake early warning according to the present invention. As shown in FIG. 2, the immediate safety evaluation method 12 for earthquake safety greatly utilizes the emergency earthquake bulletin 11 delivered before the arrival of earthquake motion for the immediate evaluation of earthquake safety of existing dams. It is assumed. When a big earthquake occurs when you forget it, it will be placed in an environment where there is little psychological time, so it will immediately and automatically predict whether or not the dam will be damaged during an earthquake and predict damage If present, it is necessary to present the situation in order to respond in an emergency.

Since the basic information of the earthquake early warning is the location and magnitude of the earthquake, the dominant frequency and maximum acceleration of the earthquake motion assumed at the dam site are estimated from this basic information using empirical formulas. For existing dam sites where seismic observation is carried out, if there is seismic observation data observed at the dam (step S22), these data will be used to amplify the seismic motion and frequency characteristics of the target dam site. Can be estimated more empirically.
(2) Earthquake Damage Evaluation Judgment Chart The earthquake damage judgment chart 14 used for immediate evaluation is a three-dimensional dynamic conducted by assuming various conditions related to the ground motion, foundation rock, reservoir etc. assumed at the dam site. Created based on the analysis result (step S23). The earthquake damage evaluation judgment chart is basically created as a relationship chart between the magnitude and epicenter distance or the maximum acceleration of seismic motion and the dominant frequency.

By the above-described immediate safety safety evaluation method 12, the information transmission 13 to the maintenance site and the safety management / efficiency / rationalization of the dam are realized (step S21).
Next, regarding the implementation of the three-dimensional dynamic analysis, as shown in the concept of FIG. 3, earthquake motion such as the maximum amplitude and dominant frequency of the earthquake motion is assumed (step S25). In addition, several conditions are set for dynamic physical properties such as foundation rock and reservoir water level (step S26), and the earthquake damage pattern of free ground 15 is classified and set.

(3) Pre-evaluation of earthquake damage by three-dimensional dynamic analysis Pre-evaluation of earthquake damage of the target dam is performed based on the result of three-dimensional dynamic analysis of the dam-foundation bedrock-reservoir coupled system. It is expected that the margin time from receiving the earthquake early warning until the main motion (S wave) reaches the dam site is from several seconds to several tens of seconds. It is currently difficult to perform a three-dimensional dynamic analysis in real time within such a short time. In addition, since there are not always engineers who are well-versed in earthquake engineering at the maintenance site of the dam, a method is required to automatically present the prediction evaluation results almost simultaneously with the reception of the earthquake early warning. Therefore, the present invention focuses on the use as a decision support system for emergency response, summarizes the results of earthquake damage analysis by three-dimensional dynamic analysis, and prepares the earthquake damage evaluation judgment chart 16. Based on the above, the dam earthquake damage prediction evaluation result is immediately presented (step S27).

  Next, an example of earthquake damage prediction by three-dimensional dynamic analysis will be described. First, there are very few examples of earthquake experiences of existing dams in the world that have a very high level of ground motion, for example, a case that experienced a shake exceeding seismic intensity 7. Regarding concrete gravity dams, arch dams, and rockfill dams, there have been no reports of cases of significant damage caused by ground motions. As to what kind of damage is assumed when it occurs, there are still areas that have been sufficiently elucidated in past earthquake damage cases alone. Therefore, in order to estimate the damage of the dam when a very strong earthquake motion is applied, a three-dimensional dynamic analysis was performed under various conditions, and the damage during the earthquake of the existing dam was examined. Dam damage is greatly affected by dam shape, structural characteristics, foundation rock characteristics, water storage conditions, ground motion characteristics, etc., and these effects were grasped and considered by three-dimensional dynamic analysis.

The following is an example of a three-dimensional analysis model of the existing dam-foundation rock-reservoir coupled system created as one of the case studies.
There are three types of reservoir depths: 75m, 90m and 104m.
The boundary condition of the foundation rock was a viscous boundary at the side boundary and a fixed boundary at the lower boundary.
The values in Table 1 were used as the physical property values used in the dynamic analysis, as a result of identification from the reproduction analysis of the actual dam behavior of the existing dam that was the subject of the case study.

  The input ground motion was input from the lower basement of the bedrock using the waves (see Fig. 4) observed at the Ichikura Dam during the Hyogo-ken Nanbu Earthquake. As shown in Table 2, the maximum acceleration amplitude is a combination of magnitude and epicenter distance, and a numerical value in the range of 100 gal to 1000 gal is set.

  With the system described above, the immediate evaluation in the event of a large earthquake can be carried out in about 1 second from the reception of the earthquake early warning to the transmission of information to the maintenance site.

  FIG. 5 is a diagram showing a flow of dam damage mode prediction by analysis according to the present invention. As shown in FIG. 5, first, dam site earthquake records are analyzed (spectrum, distance attenuation characteristics, etc.) (step S31). Next, assuming an earthquake, a ground motion taking into account the bedrock characteristics is created (step S32), and an input ground motion is created (retraction calculation) (step S33).

  Next, a three-dimensional dam-reservoir-foundation bedrock coupled model is created (step S35), and the stress is constantly analyzed (step S36). Then, the seismic response analysis is executed by using the input seismic motion analyzed in step S33 and the result of constant stress analysis in step S36 as inputs (step S37). Next, a damage form is estimated from the seismic response analysis result (step S38), and a damage form quick reference table can be created.

Details of the processing of FIG. 5 will be described below.
First, the analysis conditions of the damage form of the dam are as follows.
* Example model: 3D dam-reservoir-foundation bedrock coupled system model shown in Fig. 5 (step S35)
* For physical properties, use the values identified by inverse analysis of actual earthquake behavior.
* Seismic motion: Tokai earthquake assumed wave, Hitokura dam earthquake observation wave shown in FIG. 4 (step S31).

  The determination of damage assumes that the concrete tensile strength of 3.5 Mpa is the critical stress for crack generation, and estimates the crack generation status and the damage form of the dam (step S38).

1) Regarding dam damage analysis
(1) In the previous studies using arch-type concrete dams, analysis was performed to predict damage due to tensile failure. The damage prediction is important whether it is tensile fracture or compression fracture, but in this analysis, damage due to tensile fracture is predicted.
In fact, there is stress diffusion due to joints and cracks, so it can be said that the analysis is on the safe side.
(2) The mesh range of the reservoir area in 3D FEM analysis is important, but if the analysis target is a range that is more than three times the depth of the water, it is considered that the influence of the boundary conditions on the analysis results is small. Therefore, this time, it was set as the scope of analysis. In this analysis, the dissipation of wave energy from the reservoir bottom and upstream end is taken into account.
(3) It is necessary to pay attention to the expression of the calculation results so that the stress distribution of the concrete calculated by the continuum model is not necessarily the dam damage form itself.

2) Regarding external force
(1) Input seismic motion is used by changing the scaling of the seismic motion observed at the Ichigo (Hitokura) dam during the Hyogoken-Nanbu Earthquake. The prevailing frequency at the site was estimated and evaluated.

(2) At the stage of practical application of the prototype in the future, it is necessary to give consideration to the damage prediction by taking into account the actual earthquake type, etc. and performing analysis using appropriate observed waveforms.

(3) Although it is theoretically possible to perform dynamic analysis immediately after observing earthquake motion at a dam, the server currently in use requires more than ten hours for three-dimensional dynamic analysis. Therefore, at present, real-time correspondence of 3D dynamic analysis itself is difficult. However, if a supercomputer is used, it will be possible in the future to process 3D dynamic analysis in a short time immediately after observation of earthquake motion.

(4) If there is fault model information, it is possible to assume a seismic wave from the position information. In the case of a tsunami, the Meteorological Agency currently handles about 100,000 calculations in advance, but the assumption of seismic motion at the four target sites is at a technical stage that can be realized considerably. is there. Appropriate considering the fact that the response of the dam varies greatly depending on the relationship between the frequency characteristics of ground motion, which depends on the type of earthquake, ground conditions, etc., and the dynamic response characteristics of the dam determined according to the dam type, structure, etc. Can be set.

(5) For example, an analysis that models damage based on severe assumptions that the Nankai and Tonankai earthquakes are linked can be considered.

  FIG. 6 is a diagram showing a basic flow of dam site earthquake motion prediction based on the earthquake early warning. As shown in FIG. 6, it is necessary to select an optimum distance attenuation formula in consideration of the rock mass characteristics of the evaluation target point (step S41) (step S42). If there is seismic observation data at the point to be evaluated, the seismic motion prediction accuracy of the dam site is improved based on the information (step S43).

Then, based on the above processing results, a dam site earthquake ground motion table is created (step S44), and further, the ground table is corrected based on the earthquake observation to improve the earthquake motion prediction accuracy of the dam site (step S45).
A distance attenuation formula is used to predict the seismic motion level at the dam site based on the earthquake early warning (magnitude, epicenter position, etc.) received by the REIC from the Japan Meteorological Agency or the like. Currently, various distance attenuation formulas have been proposed, and the distance attenuation formula to be applied is selected according to the rock conditions at the dam site, such as arch dam, gravity dam, rock fill dam, earth fill dam, etc.

  Regarding the conditions of secondary disaster prediction in the dam disaster prevention method and apparatus based on the emergency earthquake bulletin according to the present invention, there is a concern about secondary disaster due to damage of the dam, not analysis of the earthquake motion actually predicted at this stage. This is done after virtually setting such earthquake motion.

  As a secondary disaster prediction method, DAMBRK, a flood prediction model due to dam breakage, developed by the US Hydrology Research Laboratory Office of Hydrology (National Weather Service (NWS), NOAA) has been published.

  The flood prediction model for dam destruction (DAMBRK) can predict flood curves in time and space in downstream areas using simple parameters. In the calculation of reservoir water storage due to runoff, inflow from upstream is also taken into account. The DAMBRK model basically consists of the time tracking technology for flood time and water level passing through the downstream area. The dynamic water level tracking technology is based on the difference calculation of weighted four-point nonlinear one-dimensional irregular fluid (Aaint-Venant Equations), and has the following analysis functions.

(1) Supercritical flow (2) Subcritical flow (3) Mixing of the above two types of flow (4) Various factors of influence can be considered in the calculation of the above three types of flow. Obstacles in the downstream area (eg road bridges, embankments, other dams, debris flow, pressure flow, reservoir waves caused by mountain slip, volume loss, invalid water storage, floodplains, etc.

  When conducting predictive analysis, it is necessary to pay close attention to the uncertainty of parameters required for modeling and parameter settings. There is a certain flexibility in entering parameters. In other words, when the parameters are not available, it is possible to set the minimum conditions, and when there are detailed parameters, very fine settings are possible.

  Examples of applications of this analysis method have been published on Teton dams and Buffalo Creek (coal-waste) dams. The calculated downstream flow rate coincides with the actual measurement value in scale and time. When the flood wave flows downstream, it attenuates suddenly, but the observed peak flow in the downstream is well reproduced.

  FIG. 7 shows a relationship curve between the water depth-water storage amount and the water depth-area of the reservoir. As shown in FIG. 7, the effective capacity curve, the total capacity curve, and the area curve are as shown in FIG. 7, where the horizontal axis represents the water storage amount and the water storage area, and the vertical axis represents the reservoir area. And as shown in FIG. 7, the relationship curve of the water depth-storage amount and water depth-area of a reservoir becomes basic conditions of secondary disaster prediction.

  Further, regarding the damage form of the dam, as schematically shown in FIG. 8, it is necessary to simulate the damaged portion 52 of the dam 51 as a trapezoid and use the opening size of the dam as an input parameter. In Japan, the prediction of secondary disasters after a dam break has never been carried out so far, but from the viewpoint of confirming the earthquake disaster prevention at the dam site, it is important to confirm the safety during an earthquake. Necessary.

  FIG. 9 is an example of a result obtained by analyzing with the condition setting illustrated in FIGS. 7 and 8. The flood process curve in FIG. 9A shows the flood process of water depth and discharge in the downstream area of the dam, and the maximum water depth distribution diagram in FIG. 9B shows the distribution of the maximum water depth.

  Next, FIG. 10 shows a standardization description image when attention is paid to the transmission of emergency earthquake warning and dam disaster prevention related information. As shown in FIG. 10, the prototype system realizes earthquake damage analysis, earthquake information utilization, and immediate information provision (step S61). And about the dam itself, the dam and earth fill dam which adjoin an urban area are made into the important object (step S62).

  In addition, in maintaining the dam facility function, automatic control of equipment (power generation, flood control, water utilization facilities, etc.) is utilized (step S63). Furthermore, as safety and security information, there is an efficiency of temporary inspection and accountability (step S64). Then, the dam equipped with the dam disaster prevention method and apparatus based on the emergency earthquake warning according to the present invention transmits the disaster information to the residents around the dam and the local government as the earthquake information transmission base (step S65). Furthermore, the utilization of the prototype system includes earthquake disaster prevention education (step S66). Earthquake disaster prevention education includes (1) prediction of earthquake damage in the ground-structure system, (2) combined use of earthquake disaster prevention information, (3) enlightenment and management of maintenance workers, and (4) neighboring residents and local governments. There is disaster prevention cooperation.

  FIG. 11 shows a description image when attention is paid to structures and facilities. As shown in FIG. 11, the emergency earthquake bulletin transmits the magnitude M of the epicenter, the epicenter distance, and the arrival time to the dam (step S71). If the seismic intensity is not 4 or more, no information is transmitted (not subject) (step S73). When the seismic intensity is 4 or more, (1) transmission of information immediately before the earthquake (step S74), (2) transmission of temporary inspection information (step S75), and (3) possibility of earthquake damage (step S76) Proceed to

  Next, if there is no possibility of earthquake damage, safety / safety information is transmitted (step S77). If there is a possibility of earthquake damage to the dam, (1) feedback to seismic reinforcement (step S78) and (2) the possibility of a secondary disaster is examined and executed (step S79). If there is no possibility of a secondary disaster, safe / safety information is transmitted (step S80).

  Furthermore, when there is a possibility of a secondary disaster, a feedback to regional disaster prevention (step S81) and warning information are transmitted (step S82).

  The dam disaster prevention method and apparatus based on the above-mentioned emergency earthquake bulletin enables real-time disaster reduction (at the time of a large earthquake) and improvement in earthquake disaster prevention (ordinary) (step S83).

  In order to effectively use emergency earthquake warnings for earthquake disaster prevention to reduce physical damage to dam facilities and various structures, it is not enough to have only the information “How many seismic intensity will come after several seconds”. , "Information on how many seismic intensity shakes, what will happen, and how to deal with it and how to deal with it" is very important. It is important to collect support / response decision support information and introduce it into an emergency earthquake bulletin utilization system.

  FIG. 12 is a diagram showing an immediate earthquake damage prediction and a secondary disaster warning system for an existing dam. As shown in FIG. 12, the system includes a real-time earthquake information utilization system 93, an immediate earthquake damage evaluation determination system 95, and a secondary disaster warning system 96. The real-time earthquake information utilization system 93 receives the real-time earthquake information provided from the earthquake observation network 91 and the Japan Meteorological Agency, etc. 94 via the real-time earthquake information utilization council 92 (hereinafter REIC), and immediately Earthquake information is transmitted to the earthquake damage determination system 95.

The immediate earthquake damage determination system 95 includes a dam earthquake damage prediction function and a secondary disaster prediction function. The function for predicting dam earthquake damage is created by consolidating the results of three-dimensional dynamic analysis conducted separately, taking into account various conditions related to dam-foundation-reservoir. Based on the dam earthquake quick reference table, the earthquake damage form of the dam is predicted (step S94). The secondary disaster prediction function predicts the risk of a secondary disaster based on a secondary disaster quick reference table created in consideration of the predicted dam damage form, water storage status, river status, and building distribution.
Then, when there is a risk of a secondary disaster, the secondary disaster warning system 96 promptly sends a warning to related parties via a plurality of warning terminals 97a and 97b. It is also used as a secondary disaster warning 98 for hydroelectric power stations.

Hereinafter, the immediate earthquake damage prediction and the secondary disaster warning system of FIG. 12 will be described in detail for each element technology.
1) Information transmission (1) The emergency earthquake bulletin transmission means transmits information distributed from the Japan Meteorological Agency from the REIC via a dedicated line, satellite line, or the like.
(2) The content of the emergency earthquake warning is only the epicenter information, but fault information etc. will be added sequentially.
(3) In dams, seismic observation has been carried out continuously since the Showa 30s, and since the Hyogoken-Nanbu Earthquake, the number of dams for which seismic observation is carried out has increased. The possibility of mutual use with seismic observation data at the dam site is also conceivable.

2) Data transmission time
(1) The average time required to receive an earthquake early warning from REIC and receive, calculate, and display at client machines installed in Tokyo and Sakuma Dam (Kanda-gun, Shizuoka Prefecture) is about 0.3 seconds (maximum) 1.0 seconds). This value has no problem in actual operation.
(2) The distribution of secondary disaster warnings was conducted in Tokyo in a simulated manner, and a demonstration test was conducted at the Sakuma Dam site using satellite packet communications.
(3) Enables simultaneous distribution to many dams in the event of a large-scale earthquake with strong shaking over a wide area.
(4) Since the number of dams where seismic observations are carried out, the mutual use with seismic observation data at dam sites will be considered in the future.
(5) Potential as a base for transmitting earthquake disaster prevention information.

Local local governments and local residents are highly interested in the safety of dams during earthquakes, and the dam location can be used as a transmission base for real-time earthquake disaster prevention information. At dam sites, it has been practiced to transmit discharge warnings using sirens, broadcasts, electric bulletin boards, etc. at the time of dam discharges, and it is possible to contribute to earthquake disaster prevention in the area around the dams.
(6) Secondary disaster mitigation / use of information after the disaster It is important to take action after the disaster, including the recovery from the secondary disaster, and it will be possible to use emergency earthquake warnings.

3) Display contents The prototype shown in Fig. 12 was installed in an actual Sakuma Dam and a demonstration experiment was conducted. The displayed contents confirmed that the damage pattern and the secondary disaster area were output normally. Real-time earthquake information transmission is possible by displaying emergency earthquake alerts in parallel with the weather condition display on the monitoring panel in the Sakuma Power Station, and by sending mail to operators who are away from the station.

4) Applicability to automatic control of dam facilities The prototype system shown in Fig. 12 has a process of immediate earthquake damage prediction and secondary disaster prediction as a method for obtaining decision support information necessary for automatic control. However, for dam facilities, automatic control of hydroelectric generators (emergency stop of power generation), spillway facilities (gate opening and closing), water intake facilities (gate opening and closing), traffic restrictions (dam top entry approach restrictions), etc. Possibility is assumed. However, for example, the gate opening / closing speed of the intake facility is about 5-8m / min even if there is a steep descent device, and the spillway gate is restricted by laws and operational regulations, but there is an There is a possibility of applying breaking news.

  If there is no possibility of damage during an earthquake, it can be used as “safety / safety information” for reporting to government agencies and responding to the area surrounding the dam. If a seismic intensity of 6 or less is assumed, and there is a risk of damage during an earthquake, temporary inspection should be performed on the terminal screen by displaying the parts that should be prioritized and prioritized. It is possible to make a smooth and efficient transition to the initial response, and for the site responsible for maintenance management, earthquake disaster prevention information that is very useful in practice can be provided. If the seismic intensity is assumed to be less than 6 and damage to the dam is predicted, it is important to prevent human damage, and to ensure earthquake disaster prevention in the downstream area of the dam, together with emergency earthquake bulletins The forecast information on damage during earthquake will be distributed to the concerned parties.

  The dam disaster prevention method and apparatus according to the earthquake early warning according to the present invention can be used to refine the quantitative evaluation of safety at the time of earthquake related to important social infrastructure facilities. Can be used to prevent secondary damage and improve local disaster prevention.

  As explained above, the disaster prevention information transmission and disaster prevention with new added value are achieved by organically linking the 3D dynamic analysis technology of the ground-structure system and the earthquake early warning, and also the disaster prevention information transmission technology. Technology can be provided. It can be applied not only to dams, but also to power transmission facilities, substation facilities, thermal / nuclear power generation facilities, and various social infrastructure facilities and urban disaster prevention.

It is a figure which shows the basic procedure about immediate evaluation of the dam disaster prevention method and apparatus by the earthquake early warning concerning this invention. It is a figure which shows the basic procedure about immediate evaluation of the dam disaster prevention method and apparatus by the earthquake early warning concerning this invention. It is a figure which shows the damage evaluation judgment chart at the time of an earthquake. It is a figure which shows the wave observed in the Ichigo dam in the case of the Hyogo-ken Nanbu earthquake. It is a figure which shows the flow of the damage form prediction of the dam by the analysis which concerns on this invention. It is a figure which shows the basic flow of the seismic ground motion prediction of a dam site based on an earthquake early warning. It is a figure which shows the relationship curve of the water depth-water storage amount and water depth-area of a reservoir. It is a figure which shows the schematic diagram of a dam damage form. It is a figure which shows an example of the result at the time of analyzing by the condition setting illustrated to FIG. 7 and FIG. It is a figure which shows the description image of the standardization at the time of paying attention to emergency earthquake bulletin and transmission of dam disaster prevention related information. It is a figure which shows the description image at the time of paying attention to a structure and a facility. It is a figure which shows the immediate earthquake damage prediction of an existing dam, and a secondary disaster warning system.

Explanation of symbols

11 Earthquake Early Warning 12 Immediate Evaluation Method for Safety during Earthquakes 13 Information Transmission to Maintenance Site 14 Earthquake Damage Judgment Chart 15 Free Ground 16 Earthquake Damage Evaluation Judgment Chart 51 Dam 52 Damaged Location 91 Earthquake Observation Network 92 Real-time Earthquake Information Usage Council (REIC)
93 Real-time earthquake information utilization system 94 Japan Meteorological Agency etc. 95 Immediate earthquake damage determination system 96 Secondary disaster warning system 97a Alarm terminal 97b Alarm terminal 98 Secondary disaster warning

Claims (7)

Estimate the ground motion expected at the dam site from the location and magnitude of the earthquake early warnings delivered before the arrival of the ground motion,
Predict the damage of the dam site by three-dimensional dynamic analysis based on the physical properties of the estimated ground motion, foundation rock, and reservoir,
Predict the risk of secondary disaster from the predicted damage of the dam site,
A dam disaster prevention method using an earthquake early warning, wherein the predicted damage to the dam site and the risk of a secondary disaster are distributed together with the earthquake early warning. A dam-site ground motion estimation means for estimating the ground motion assumed at the dam site from the location and magnitude of the emergency earthquake bulletin delivered before the arrival of the ground motion;
Damage prediction means for predicting damage to the dam site by three-dimensional dynamic analysis based on physical properties related to the ground motion, foundation rock, and reservoir assumed at the dam site estimated by the dam site earthquake motion estimation means;
Secondary disaster prediction means for predicting the risk of secondary disaster from damage of the dam site predicted by the damage prediction means;
Disaster prevention information distribution means for distributing information on damage of the dam site predicted by the damage prediction means and risk of secondary disaster predicted by the secondary disaster prediction means together with the emergency earthquake warning. A dam disaster prevention device based on the earthquake early warning. In the three-dimensional dynamic analysis, a stress analysis is performed using a three-dimensional dam-reservoir-foundation bedrock coupled model, and the damage form is estimated from the ground motion considering the rock characteristics and the analysis result of the stress. A dam disaster prevention device according to the earthquake early warning according to claim 2. 4. The damage prediction unit includes a damage quickness table created by the three-dimensional dynamic analysis, and predicts damage of a dam site based on the damage quickness table. Dam disaster prevention equipment by early earthquake early warning. The dam site seismic motion estimation means has a dam site seismic motion preparatory table created by selecting the optimum distance attenuation formula in consideration of the rock mass characteristics of the evaluation target site and estimating the maximum acceleration and dominant frequency of the seismic motion, 5. The dam disaster prevention device according to any one of claims 2 to 4, wherein the earthquake motion is estimated based on a site earthquake motion quick-view table. The secondary disaster prediction means has a secondary disaster quick reference table created in consideration of the predicted damage of the dam site, water storage status, river status, building distribution, and 2 based on the secondary disaster quick reference table. The dam disaster prevention device according to any one of claims 2 to 5, wherein the risk of a next disaster is predicted. The disaster prevention information distribution means distributes information on seismic reinforcement when there is a possibility of dam site damage as predicted by the damage prediction means, and there is a possibility of secondary disaster as prediction by the secondary disaster prediction means 7. In the case, regional disaster prevention information and warning information are distributed, and when there is no possibility of the damage or secondary disaster, reliable / safety information is distributed. A dam disaster prevention device based on the earthquake early warning.

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