JP2006183274A - Method and apparatus for predicting sewer pipe damage in sewer network - Google Patents

Abstract

[PROBLEMS] To provide a sewer pipe network that can efficiently and quantitatively evaluate the degree of damage, has a function of creating an appropriate repair plan based on the survey results, and supports the efficient operation of sewerage facilities. Provide an integrated management system.
SOLUTION: Environmental data is continuously collected from all manholes in the sewer network using a specific manhole as a monitoring point, and environmental data of an arbitrary sewer pipe is estimated, and each environmental data is estimated based on the estimated environmental data. Estimate the degree of damage and create information to support the ranking of repair works in the sewer network.
[Selection] Figure 1

Description

  The present invention relates to a method for predicting damage to pipelines in maintenance management of sewer facilities.

  Sewerage facilities for efficiently treating various types of wastewater such as domestic wastewater, factory wastewater, and rainwater have become indispensable for modern urban life. The number of sewer pipes exceeding 60% and over 50 years of construction is increasing, so it is said that the sewerage business is entering an era of maintenance. The total length of pipe laying is about 32km nationwide, and the usage rate by pipe material is 50% for hard vinyl chloride pipes, 30% for concrete pipes, 10% for ceramic pipes, and 10% for others. Yes.

  It is extremely important to efficiently maintain and manage such a huge amount of sewerage facilities, and further to extend its lifespan. Attempts have been made to utilize IT (information technology). For example, the construction of a sewer optical network system has been promoted as a national policy, and the digitization of a sewer ledger (sewage ledger system) has been promoted.

  The sewerage optical network system is intended to configure the network by connecting the sewerage facilities with optical fiber cables. The system aims to make up for the lack of human resources for maintenance and to improve the maintenance in the future. . The computerization of the sewer ledger is a document that lists the sewer ledger diagram, which is a drawing showing the layout of sewer facilities, and the type and number of manholes, the length of sewer extension, the type of sewage and rainwater, etc. Data), and is intended to automate maintenance in the future.

  As such prior art, for example, in Patent Document 1 (Sewer Optical Network System), cable information related to the specifications of optical fiber cables laid in the sewer facility, map information of the sewer facility such as the piping route of the sewer pipe, and the like A sewer optical network system is disclosed in which various information and measurement information obtained by measuring an optical fiber cable are collectively managed, and abnormality detection and periodic inspection of a sewer facility are performed by a computer.

  Further, in Patent Document 2 (3D buried pipe comprehensive system), the map data includes the graphic data of the top view of the terrain necessary for the design of the buried pipe and the pipe attribute data such as the numerical value accompanying the graphic data as map information. And calculate the flow rate to detect the appropriate cross section and gradient based on the input buried pipe route, create a pipe system diagram including graphic data of the longitudinal section, based on the pipe system diagram, Digital information such as investigation, inspection, and cleaning of buried pipes using digital cameras can be imported as maintenance management data, and the maintenance management data can be easily recognized visually using 3D CAD in combination with map information. A three-dimensional buried pipe dredging system that displays and outputs a stereoscopic image is disclosed.

  Patent Document 3 (Preventive Maintenance Method, Preventive Maintenance System, Structure Database, Structure Chart, Private Fund Introduction Method, and Private Fund Introduction System in Structure Maintenance) has various specialized knowledge or experience. With the support of product specialists, a preventive maintenance method is disclosed that quantitatively grasps the current state including the tendency of deterioration, and copes with maximizing the lifetime, durability, and asset value according to the present state, In Patent Document 4 (sewerage laying design support system and recording medium), drawing is made based on sewerage planning data for the purpose of improving the efficiency and labor saving of a series of data processing from planning design, construction work, and post-laying management. The plan drawing and plan calculation form are created according to the table conditions and the plan drawing is prepared into sewerage facility data that can be linked to GIS (geographic information system) after completion. Fixed by work with GIS and realizes the search and management of information map-based, comprehensive sewage management system was also available to various requirements, such as construction of Other utilities are disclosed.

  Patent Document 5 (Neural Network Application Rainwater Inflow Prediction Device) includes learning result information input means for the purpose of automatically and highly accurately predicting rainwater peak inflow for pump operation support, Predictive model construction means for learning a neural network weight coefficient from the result information, inflow quantity prediction means for predicting rainwater inflow quantity by the prediction model, and output means for outputting the predicted rainwater inflow quantity. A neural network applied rainwater inflow prediction apparatus is disclosed.

  Patent Document 6 (Ground Pipe Structure Design Method) discloses a technique that uses a genetic algorithm in designing the underground pipe structure, and in order to reduce the computation time, A technique that further employs local search in the process of searching for an optimal design proposal using a genetic algorithm is disclosed. In other words, the genetic algorithm is a method for finding the optimal solution by repeating the operations of determining an excellent gene under constraints and generating a next generation gene by storage, selection, selection, crossover, mutation, etc. This is a well-known technique as a suitable method for obtaining an optimal combination satisfying the constraint condition from a large number of combinations.

  Although not directly related to sewerage facilities, Patent Document 7 (Method for Determining Optimal Replacement Time of Boiler Components) discloses that a genetic algorithm is applied to a boiler preventive maintenance plan. In other words, the number of replacement parts is large, and the inspection cost increases if the parts become more sophisticated. Since there are many evaluation factors, such as reducing the replacement cost if multiple parts are replaced at the same time, all combinations are evaluated. A technique for calculating an optimal component replacement time in a life cycle by applying a genetic algorithm in a preventive maintenance plan for a boiler that cannot be disclosed is disclosed.

  As described above, a technique for efficiently maintaining and managing a sewerage facility by utilizing IT that has been developed in recent years, and further extending its life, etc. It is a technique that can be suitably used in

  On the other hand, in order to efficiently maintain and manage sewerage facilities, it is extremely important to conduct appropriate damage diagnosis and appropriate repair work based on the results of the investigation. Although it is necessary to ascertain the quantitative damage level for each element that makes up the sewer network and to rank the degree of damage, there is still disclosed a technology that can efficiently and quantitatively evaluate the degree of damage. Absent.

  That is, in general, a visual inspection or a TV camera is used to conduct an external appearance survey, and if necessary, a detailed survey is performed by conducting a physical property survey with the core removed. It is an inefficient method, and it is not possible to inspect the appearance of all sewage pipe networks with a very long total length when planning repair work within the fiscal year. The actual situation is that the appearance survey is performed by comprehensively evaluating the above and selecting the sewer pipe where the progress of damage is expected, and the appearance survey by visual inspection or the like cannot be quantitatively evaluated.

  In Patent Document 8 (Reinforced concrete pipe inspection method and inspection equipment), a shock elastic wave test by hitting a hammer or a steel ball is performed to measure a propagation wave of the target pipe, and a resonance frequency spectrum of the propagation wave is obtained. A technique for analyzing and quantitatively evaluating the degree of damage from the area ratio between the area of the high frequency component and the area of the low frequency component of the resonance frequency spectrum is disclosed. However, in this prior art, it is impossible to permanently install a device for generating such a shock wave or a device for measuring a propagation wave in an extremely long sewer network, and while carrying or moving them, Even if it must be measured and a quantitative evaluation can be made, it must be said that it is a very inefficient method, and it is not a satisfactory technique.

  Further, Patent Document 9 (embedded object management method and apparatus and wireless tag) embeds underground as a method for obtaining information on changes in the state of buried objects such as gas pipes and water and sewage pipes in real time from the ground with high accuracy. In the wireless tag attached to the object, the data (vibration, elongation, etc.) detected by the sensor provided in the wireless tag, along with the information at the time of embedding (type of pipe, depth at the time of embedding, date of embedding, direction of embedding, etc.) (Amount, internal pressure, etc.) are stored, and a response corresponding to the stored data is performed with the wireless tag for the electromagnetic wave indicating the data request from the ground wireless device, and the response is detected by the wireless device. An embedded object management method is disclosed. However, in this conventional technology, it is necessary to permanently install a large number of wireless tags equipped with such vibration sensors in an extremely long sewer network, and maintenance and management thereof may be necessary. It must be said that it is an inefficient method such as an increase in management costs, and it is not a satisfactory technique.

  The conventional technology for diagnosing the degree of damage to buried sewer pipes has a common feature in directly investigating the target sewer pipes in connection with the preventive maintenance system in the maintenance management of sewer facilities. In addition, by visual inspection such as visual inspection and using a suitable sensor, various damages such as pipe breakage, cracks, seam misalignment, pipe slack, pipe meandering, foreign matter adhesion, pipe corrosion, mounting pipe protrusion, etc. Although it is possible to conduct a diagnostic investigation, as described above, there are problems in that it requires a lot of manpower and inefficiency such as an increase in cost.

  On the other hand, among these damages, corrosion of sewer pipes, especially corrosion of concrete pipes caused by microorganisms such as sulfate-reducing bacteria, is strongly affected by the environmental conditions (in water or in the air) with which the sewer pipes come into contact. It is impossible to estimate the degree of damage based only on the number of years passed, and various preventive measures (for example, Patent Document 10 (antibacterial sewer pipe and manufacturing method thereof), Patent Document 11 (hydrogen sulfide removal device in wastewater)) Although proposed, it has become one of the major injuries that require proper diagnostic investigation.

  The mechanism of this corrosion is that after sulfate ions contained in wastewater become hydrogen sulfide by the activity of sulfate-reducing bacteria under anaerobic conditions, this hydrogen sulfide moves from the liquid phase to the gas phase, After dew condensation on the concrete wall exposed to the gas phase with water vapor etc. due to temperature difference etc., this hydrogen sulfide is oxidized to high concentration sulfuric acid by the action of sulfur oxidizing bacteria under aerobic condition, and the high concentration It is known that concrete is eroded by sulfuric acid.

  Relational expressions for estimating the rate of sulfide formation in sewage using sulfide concentration, BOD, etc. as parameters, relationship of molecular state ratio in sewage (equilibrium relationship between hydrogen sulfide and sulfide with pH as parameter), water temperature, etc. The solubility relationship of hydrogen sulfide in sewage as a parameter, the relational expression for estimating the depth of corrosion using the hydrogen sulfide concentration in the air and the service life as a parameter, etc. are known (for example, Non-Patent Document 1 (Guideline for sewerage maintenance management) EPA (United States Environmental Protection Agency) formula, etc.)

  Based on the diagnosis of the degree of damage to the sewage pipeline, select an appropriate repair method from the pre-registered repair methods based on the efficient maintenance and management of sewerage facilities, including the implementation of appropriate repair work, and the annual budget. Supporting the efficient operation of sewerage facilities, such as the creation of repair plans to be performed, and the prediction of future changes in the extent of damage, and the creation of repair plans to minimize LCC (life cycle cost) An integrated management system for the sewer network has not yet been developed.

JP 2003-234708 A JP 2002-324096 A JP 2002-201608 A JP 2001-325310 A JP 05-134715 A JP 2002-189769 A JP 2000-172663 A JP 2004-028976 A JP-A-11-287866 JP 2003-138634 A JP 09-141293 A Sewerage Maintenance Guidelines -2003, Japan Water Works Association

  The present invention effectively and quantitatively predicts the degree of damage to pipelines in order to effectively carry out preventive maintenance in sewerage facility maintenance, and creates an appropriate repair plan based on the prediction results. This will support the efficient operation of sewerage facilities.

  Select a specific point in the sewer network as a monitoring point, measure environmental data that affects the damage of the sewer pipe, and based on this environmental data and the map information of the sewer network, environmental data at any location in the sewer network Is estimated, and the damage of the sewer pipe is estimated based on the obtained environmental data, sewer pipe attribute information and the service life.

  The monitoring point for collecting environmental data is preferably a manhole having a sewage confluence, a bending point, or a stepped point from the viewpoint of installation and maintenance of the measuring device. The estimated accuracy is obtained by comparing the estimated value of the environmental data and the actually measured value at the estimated point. If the accuracy is low, the monitoring point is changed to increase the estimated accuracy.

  Environmental data uses DO (dissolved oxygen concentration), BOD (biochemical oxygen demand), water temperature, flow rate, pH, sulfide concentration, and hydrogen sulfide concentration in the air, and these parameters are used as parameters. This is to estimate the degree of damage.

The environmental data is collected discretely or continuously (continuously), and the data is collected using a complex sensor having measurement, storage and transmission functions.
The attribute information of the pipe line includes an inner diameter, a thickness, an outer diameter, a maximum outer diameter, an effective length, a type, and a hydraulic gradient of the sewer pipe.
As a method for estimating the environmental data of the sewer pipe, a neural network can be used. In order to display information for supporting the ranking of repair works on a monitor, it is possible to accurately display a sewer network on a map using a GIS (Geographic Information System).
The information that supports the ranking of repair work based on the estimated degree of damage is the information that supports the ranking of detailed surveys, and selects and selects multiple sewer pipes for detailed survey based on the support information. The degree of damage is measured for the measured sewer pipes, and based on the magnitude of the actually measured degree of damage, the repair work for the plurality of sewer pipes is ranked.

Determine the degree of urgency / risk from the estimated or measured damage level and the required performance of the estimated or measured location, and select the appropriate repair method d from the pre-registered repair methods based on the annual budget. Create a repair plan.
The future transition of the degree of damage is further predicted, and based on the annual budget, a repair plan is created using a genetic algorithm so as to minimize LCC (life cycle cost) from a repair method registered in advance.

  As described above, the corrosion of concrete pipes caused by microorganisms such as sulfate-reducing bacteria will be described as typical damage to sewer pipes. However, the present invention is based on the environmental conditions (water or air) of the place where the sewer pipes are installed. It is also appropriate to target damage that is strongly affected, for example, corrosion of rebars caused by the progress of neutralization due to carbon dioxide in the atmosphere or acid substances contained in rain, cracks in concrete due to expansion, etc. It becomes possible by measuring environmental data.

  The present invention has two major features. The first feature is that environmental data, which is a cause of sewer pipe damage, is collected using a specific manhole as a monitoring point, and environmental data at other locations is estimated based on the collected environmental data. The second feature is to estimate the degree of damage at the location based on the estimated environmental data. That is, the present invention estimates environmental data that is a cause of sewer pipe damage, and estimates the degree of damage based on the estimated environmental data. Furthermore, it can be used for ranking repair works based on the estimated degree of damage.

The first feature utilizes the fact that a long sewage network consists of a plurality of manholes and a plurality of sewage pipes connecting them to form a connected network system, and is regarded as a network system. This is to estimate environmental data at other locations.
The environmental data for the manhole on the downstream side can be estimated as the sum of the environmental data for the upstream manhole and the amount of change in the sewer pipe connecting the two, and the environmental data for the manhole at the junction where multiple sewer pipes are connected Can be estimated by weighting the respective environmental data to be merged with the respective inflow amounts.

  The amount of change in the sewage pipe can be estimated by, for example, an EPA (United States Environmental Protection Agency) equation as described above. The EPA formula is specifically shown in the examples described later.

  The second feature is to estimate the degree of damage at the location based on the estimated environmental data. The degree of damage based on the environmental data is estimated, for example, as described above. It can be performed using conventional techniques such as a relational expression for estimating the corrosion depth using the hydrogen concentration and the service life as parameters.

A separate ID is assigned to each manhole in the sewer pipe network and the sewer pipes connecting the manholes, and environmental data that cause sewer pipe damage is collected using specific manholes as monitoring posts. Estimate the environmental data of any sewer pipe based on the map information and attribute information of the sewer pipe network, and determine the degree of damage of the sewer pipe based on the estimated environmental data and the attribute information of the sewer pipe and the years of service. By estimating, the degree of damage to any sewer pipe can be estimated.
Based on the estimated degree of damage, it is possible to rank repair works for each sewer pipe in the sewer network.

  The “map information” in the present invention is information corresponding to a sewer ledger diagram, and is information on a drawing that shows the layout of sewer facilities in a plane. The “attribute information” in the present invention is This is information such as the type and number of manholes, the length of sewer, the type of sewage and rainwater.

  As mentioned above, corrosion of concrete pipes caused by microorganisms such as sulfate-reducing bacteria causes the sulfate ions contained in wastewater to become hydrogen sulfide due to the activity of sulfate-reducing bacteria under anaerobic conditions. After moving from the phase part to the gas phase part and condensing on the concrete wall exposed to the gas phase part with water vapor etc. due to temperature difference etc., this hydrogen sulfide is oxidized by the action of sulfur oxidizing bacteria under aerobic condition It is known that the concentration of sulfuric acid becomes high, and concrete is corroded by this high concentration sulfuric acid, and it is known that the degree of corrosion can be estimated by grasping the amount of hydrogen sulfide generated from sewage. .

  In addition, as described above, a relational expression for estimating the rate of sulfide formation in sewage using sulfide concentration, BOD, etc. as a parameter, a relationship between molecular state proportions in sewage (equilibration of hydrogen sulfide to sulfide using pH as a parameter) Relationship), the solubility relationship of hydrogen sulfide in sewage using the water temperature as a parameter, and the relational expression for estimating the corrosion depth using the hydrogen sulfide concentration in the air and the years of service as parameters.

  Specifically, the rate of sulfide formation in sewage is estimated from sewage DO (dissolved oxygen concentration), BOD (biochemical oxygen demand), water temperature, and flow rate, for example, using the EPA equation. The amount of sulfide produced can be estimated from the production rate and the residence time in the target sewer pipe. The residence time referred to here is an average time required for sewage to pass through the target sewage pipe, and can be calculated from the inner diameter, effective length, and flow rate of the sewage pipe.

  Specifically, the hydrogen sulfide concentration in the air is estimated based on, for example, the relationship between the molecular state ratio of sewage using pH as a parameter and the solubility relationship of hydrogen sulfide in sewage using water temperature as a parameter. be able to.

  If the hydrogen sulfide concentration in the air can be estimated, the damage rate can be estimated in relation to the service years, and the damage depth can be estimated from the damage rate and the service years. Furthermore, the urgency / risk can be determined from the estimated damage depth and the required performance of the sewer pipe, for example, the allowable minimum wall thickness or the allowable corrosion depth.

  The present invention greatly reduces the number of monitoring points for collecting environmental data that is a cause of sewage pipe damage when estimating the degree of damage at any point of the sewage pipe network without relying on subjective judgment such as visual inspection. It is possible to quantitatively estimate the degree of damage at an arbitrary location based on environmental data collected at a small number of measurement points.

  A monitoring point for collecting environmental data is suitable in the vicinity of a severely damaged part, for example, a manhole having a sewage confluence, a bending point, or a stepped point. This is because sewage is vigorously mixed at these locations, so that the amount of hydrogen sulfide generated is large and the corrosion of the concrete is likely to proceed.

  In particular, when estimating environmental data using a relational expression such as the EPA formula, the minimum required manhole for logically estimating the environmental data is selected from the network configuration of the target sewer network. .

  Although it is desirable to reduce the number of monitoring points, in general, the estimation accuracy decreases when the number of monitoring points is reduced. Therefore, when selecting monitoring points, an allowable estimation error is set and the number of monitoring points is reduced as much as possible within that condition, but long-term results data are required to determine the location and number of monitoring points. Yes, the estimated value of environmental data is compared with the actual measurement value, and the location and / or number of monitoring points are changed based on the estimation accuracy.

That is, after selecting a monitoring point for the first time, the estimated value and the actual measurement value are compared, the suitability of the monitoring point is determined based on the estimation accuracy, and the monitoring point is reviewed.
In determining whether or not a monitoring point is suitable, the location and number of monitoring points are determined on the condition that they are within an allowable estimation error. In addition, the number of monitoring points is fixed, and the estimation accuracy can be improved by optimizing the location. it can.

  Manholes are convenient because they can be easily installed and inspected and maintained by sensors for measuring environmental data. However, monitoring points are not limited to manholes, and are not limited to sewage pipes. The monitoring point can be in the middle or the entrance to the sewage treatment plant.

  The environmental data used for estimation varies depending on the estimation method, but when using the EPA formula, DO (dissolved oxygen concentration), BOD (biochemical oxygen demand), water temperature, flow rate, pH of sewage , Sulfide concentration, and hydrogen sulfide concentration in the air are required.

  It is preferable to collect environmental data continuously. Although these environmental data change daily and yearly, it is not always clear what values should be used, such as whether to use representative values or average values when estimating the degree of damage to sewer pipes. It is also different depending on the estimation method.

  It is desirable to use representative values to reduce the computational load, but to enable accurate estimation of the degree of damage and to reduce the computational burden, environmental data must be continuously Need to collect.

  In the case of continuous data collection, a complex sensor equipped with data measurement, storage and transmission functions is installed at the monitoring point, and environmental data is collected by receiving signals transmitted from the complex sensor.

  Since the sewer pipe is buried in the ground, it is time-consuming and dangerous work for human beings to enter the pipe line, and it is difficult in practice. For continuous data collection, it is realistic to install a complex sensor and transmit data wirelessly at a fixed time.

  The combined sensor is a source of sewage damage such as DO (dissolved oxygen concentration), BOD (biochemical oxygen demand), water temperature, flow rate, pH, sulfide concentration, hydrogen sulfide concentration in the air, etc. It consists of a sensor that measures certain environmental data, a memory such as a RAM that stores the measured data, a transmitter that transmits the stored data periodically and / or on demand, and a power supply and controller Is done.

  The attribute information relates to the type and number of manholes, the length of sewer extension, the type of sewage and rainwater, etc. When estimating environmental data using the EAP formula, the inner diameter of the sewer pipe, Includes thickness, outer diameter, maximum outer diameter, effective length, type, and hydraulic gradient. The inner diameter and hydrodynamic gradient are related to the flow velocity, the effective length is related to the residence time of the sewage, and the inner diameter and thickness are related to the allowable corrosion depth.

  This environmental data is estimated based on the relational expression for estimating the rate of sulfide formation in sewage using sulfide concentration and BOD as parameters, and the relationship of molecular state ratio in sewage (from hydrogen sulfide to sulfide using parameters such as pH). Equilibrium relationship), solubility of hydrogen sulfide in sewage using parameters such as water temperature as parameters, but not limited to this, estimation of environmental data of any sewer pipe can be performed using a neural network. Can be done.

  As is well known, a neural network is a calculation method based on a model of a brain or a neural network, and has a hierarchical structure of an input layer, an intermediate layer, and an output layer. Characterized by applying weights to external outputs. The intermediate element constituting the intermediate layer of the neural network is also called a basis function, and an arbitrary function can be used. For example, a radial basis function (RBF) is preferably used. A feature of radial basis functions is that the response of the function decreases monotonically (or increases) with distance from the center point, and the center, distance scale, and exact shape of the radial basis functions are parameters of the model. Examples of radial basis functions include Gaussian functions.

  The learning data used for learning of the neural network is a data set of factor index data and teacher data to be estimated based on the factor index, and in the present invention in which the degree of damage to the sewer pipe is to be estimated based on environmental data. The environmental data is the factor data, and the degree of damage is the teacher data.

  When using a neural network, as shown in Patent Document 5 described above, first, learning result information (learning data) is first collected, and the weight information of the neural network is determined by learning the result information. The decision is made, an estimation model is constructed, and the estimation model is estimated using the constructed estimation model. The neural network usually has an additional learning function, and updates the estimation model by performing additional learning.

  By estimating the environmental data using a neural network, even if the generation mechanism is not clear, or even if the generation mechanism is clear but the relational expression has not been established, it can be estimated from the environmental data collected at the monitoring point. Can estimate environmental data for any sewage pipe.

  When using a neural network, in order to collect the learning performance information necessary for constructing the estimation model, the amount of sulfide in the sewage and the air in the air, including the location to be estimated, for at least a certain period of time Needless to say, environmental data such as hydrogen sulfide concentration must be measured.

In order to display the ranking of repair works, a sewer pipe network is displayed on a map displayed on a monitor using a GIS (Geographic Information System).
GIS (Geographic Information System) is software that has the function to link various characters, numbers, images, etc. to a map, search, combine and analyze various information on a computer and express the results on a map. All the manholes in the sewer pipe network and all the sewer pipes connecting them are assigned individual IDs, the sewage pipe network including the individual IDs on the map, the urgency / risk to the sewer pipe network The color of the determination result can be displayed.

By using the GIS (Geographic Information System), it is possible to prevent erroneous input during the data input operation when collecting environmental data measured at the monitoring point, and to improve the input operation efficiency.
Obviously, the measured environmental data must be accurately input as the value at the monitoring point, but the sewer pipes are not only constructed in a complex network but also in underground structures. For this reason, it is very difficult to identify manholes. On the other hand, by using the GIS (geographic information system), by making it possible to identify each position of the manhole of the sewage pipe network on the map, it is possible to prevent erroneous input during the input operation of the measured environmental data, The input work can be made efficient.

  Estimate the environmental data of other locations based on the measured environmental data, estimate the extent of damage at that location based on the estimated environmental data, and rank the repair work based on the magnitude of the estimated extent of damage In addition to the form of creating information for supporting the date, the support information is used as information for supporting the ranking of detailed surveys. Further, a plurality of sewer pipes for detailed surveys are selected based on the support information, and the selected It is possible to measure the degree of damage on the water pipes, and to indicate the ranking of the repair work of a plurality of actually measured sewer pipes based on the magnitude of the actually measured degree of damage.

  If the estimated degree of damage is not sufficient to rank the sewage pipe repair work, further visual inspection using a TV camera, physical property inspection without a core, hammer, steel ball, etc. A ranking is made by conducting a detailed investigation such as an impact elastic wave test by hitting or an X-ray method, an electromagnetic wave method, an infrared method, an ultrasonic method, or the like.

    Determine the degree of urgency / risk from the degree of damage and the required performance of the sewer pipes estimated or measured, and select an appropriate repair method from pre-registered repair methods based on the annual budget. Create a plan. In addition to information that supports the ranking of repair works, a repair plan is also prepared, including the appropriate repair methods.

  The repair plan is usually determined based on the degree of urgency / risk and the annual repair budget, but in general, various repair methods are possible even with the same damage, including evaluation of cost and effectiveness. It is extremely difficult to select an appropriate repair method, and various repair methods are registered in advance and registered in accordance with predetermined procedures set based on urgency / risk and annual repair budget. Select an appropriate repair method from the repair methods.

  In the predetermined procedure set, the urgency / risk level is ranked, and the repair method that achieves the expected life set for the sewer network is selected in descending order of the rank, and the cost is the lowest among them. Select the appropriate repair method for the sewer pipe, and select the repair location and the appropriate repair method on the condition that the total cost is within the annual repair budget.

  The repair plan can also use well-known LCCA (life cycle cost analysis) and RM (risk management) techniques. Based on environmental data, etc., further predict the future transition of the extent of damage, and use a genetic algorithm to minimize LCC (life cycle cost) from pre-registered repair methods based on the annual budget Create a repair plan.

  FIG. 1 shows a schematic diagram showing a part of a sewer network on a screen of a damage prediction apparatus. Of these, 12 manholes were selected as monitoring posts, giving priority to sewage confluence, inflection point, and stepped point, DO (dissolved oxygen concentration), BOD (biochemical oxygen demand), water temperature Water depth, pH, sulfide concentration, and atmospheric hydrogen sulfide concentration were measured five times a day.

  Map information and attribute information of the sewage pipe network use the database that has been prepared in advance from the sewer ledger diagram at the time of laying the sewage pipe network and related records, and the attribute information includes the inner diameter, thickness, Includes outer diameter, maximum outer diameter, effective length, type, hydraulic gradient.

  The manhole of the sewer network shown in FIG. 1 is selected as a monitoring point, and as shown in FIG. 2, environmental data measured at the selected point is input on the input screen.

  Environmental data is read from the specifications of the sewer pipes and the database of environmental input data so far, and the estimated calculation of the degree of damage is executed. In addition, FIG. 3 is a data structure required for estimation to the extent of damage, such as the specification of a sewer pipe.

  The EPA formulas (1) and (2) were used to estimate the rate of sulfide formation that affects the corrosion of sewer pipes. Expression (1) is a case of a natural flow pipe, and Expression (2) is a case of a pressure feed pipe.

S _N is the sulfide concentration in the natural flow down pipe (mg / L), h is the time (h), BOD is the biochemical oxygen demand (mg / L), T is the temperature of sewage (° C.), R is the diameter Depth (m), which is the cross-sectional area of the water surface divided by the wet side length. S _P is the sulfide concentration in the pumping tube (mg / L), d is the tube diameter (m).

  When using this EPA formula, bacteria that produce sulfide are activated in an environment where DO is 1.0 mg / L or more. Therefore, when DO is 1.0 mg / L or more, DO is the minimum time. When the DO value was less than 1.0 mg / L, the BOD value at the time indicating the average DO value was used as the representative value for the day.

The sulfide concentration S _{E at} the location where damage is predicted is estimated by the formula (3) from the sulfide generation rate estimated from the measurement value of the monitoring point related to the network and the sulfide concentration S _S of the monitoring point. . In addition, as the average sulfide concentration S in the pipe rod, a simple average of S _E and S _S was used.

H = L / 3600v, v = 1 / n × R ^2/3 × I ^1/2 , H is tube retention time (h), L is tube extension (m), v is the average flow velocity in the tube (M / s), n: Coefficient of roughness (Fume tube is 0.013), and I is a hydraulic gradient.

  Not all sulfides generated in sewage are diffused into the atmosphere, but hydrogen sulfide is diffused into the atmosphere, and ionic sulfides and molecular sulfides of dissolved sulfides in sewage (ie hydrogen sulfide) ) And the solubility of hydrogen sulfide in sewage determine the amount of hydrogen sulfide diffused into the atmosphere. These relations generally use the pH and temperature of sewage as parameters, and detailed explanations are omitted. However, the hydrogen sulfide gas concentration in the air is estimated based on the estimated sulfide concentration and these relations.

  The degree of damage based on the concentration of hydrogen sulfide in the air is estimated based on the corrosion depth of the sewer pipe. The depth of corrosion was determined using equation (4). In the formula, D is the depth of corrosion (mm), C is the concentration of hydrogen sulfide in the atmosphere (ppm), and t is the years of service (years).

  The urgency / risk level judgment line based on the estimated depth of corrosion is a depth of corrosion that is 1/3 or more of the pipe thickness, which is attribute information. If this depth is exceeded, it is judged as dangerous, and this risk level is judged as dangerous. Sewage pipes were selected as candidates for repair.

  As described above, the degree of damage is estimated for the entire sewer pipe network, and the urgency / risk level for the degree of damage is determined, and the sewage pipe repair work is ranked based on the determination. FIG. 4 is an example of a display of information on ranking of repair works for the sewer pipe network.

The schematic diagram which shows a part of sewer network. It is an example of the monitor screen for inputting environmental data. It is an example of the data structure regarding estimation of a damage grade. It is an example of a determination result of estimating the degree of damage and determining the degree of urgency / risk.

Claims (12)

  All the manholes in the sewer network and all the sewer pipes connecting the sewer pipes are distinguished by assigning individual symbols, and environmental data related to the cause of sewer pipe damage is collected using specific manholes as monitoring points. Estimate the environmental data of any sewer pipe based on the collected environmental data and the map information and attribute information of the sewer pipe network, and based on the estimated environmental data, the attribute information of the sewer pipe and the years of service Estimate the degree of damage to any sewer pipe as if estimating the degree of damage to the water pipe, and rank the repair work for each sewer pipe within the sewer network based on the magnitude of the estimated degree of damage. An integrated management system for sewage pipe networks characterized by creating information that supports   The integrated management system for a sewage pipe network according to claim 1, wherein the specific manhole as the monitoring point includes a manhole having a sewage confluence, a bending point, or a stepped point.   The estimated value of the environmental data is compared with the actually measured value at the estimated point, and the location and / or number of the specific manhole as the monitoring point is changed based on the estimated accuracy. An integrated management system for a sewer network according to claim 2.   The environmental data includes DO (dissolved oxygen concentration), BOD (biochemical oxygen demand), water temperature, flow rate, pH, sulfide concentration, and atmospheric hydrogen sulfide concentration. The integrated management system of the sewer pipe network of Claim 1 thru | or 3.   5. The integrated sewer network management system according to claim 1, wherein the collection of environmental data is continuous collection of environmental data.   The environmental data is collected by installing a complex sensor having functions for measuring, storing and transmitting the environmental data in the specific manhole and receiving a signal transmitted from the complex sensor. The integrated management system of a sewage pipe network according to claim 5, wherein   7. The sewer network integration according to claim 1, wherein the attribute information includes an inner diameter, a thickness, an outer diameter, a maximum outer diameter, an effective length, a type, and a hydraulic gradient of the sewer pipe. Type management system.   The integrated sewer network management system according to any one of claims 1 to 7, wherein the estimation of the environmental data of the arbitrary sewer pipe is an estimation performed using a neural network.   9. The integrated sewer network management system according to claim 1, wherein the sewer network can be displayed on a map using a GIS (geographic information system).   The information that supports the ranking of repair work based on the estimated degree of damage is information that supports the ranking of detailed surveys, and selects a plurality of sewer pipes to be surveyed in detail based on the support information, Measure the degree of damage for the selected sewer pipes, and create information that supports the ranking of the repair works of the plurality of sewer pipes measured based on the magnitude of the measured degree of damage. The integrated management system of the sewer pipe network of Claim 1 thru | or 9.   Determine the degree of urgency and risk from the estimated or measured damage level and the required performance of the estimated or measured location, and select an appropriate repair method from pre-registered repair methods based on the annual budget. An integrated management system for a sewage pipe network according to claim 1, wherein a repair plan is created.   Based on the environmental data, etc., further predict the future transition of the extent of the damage, and based on the annual budget, a genetic algorithm that minimizes the LCC (life cycle cost) from a pre-registered repair method 11. An integrated management system for a sewage pipe network according to claim 1, wherein a repair plan is used to create a repair plan.

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