JP2006348570A - Filling detecting method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a filling state to a filling object space such as a form and a sheath pipe of a fluid body such as concrete and grout in civil engineering construction or building construction, by saving electric power. <P>SOLUTION: This filling detecting method includes at least a step of impressing voltage on a pair of electrodes of inserting a resistance element between the electrodes over a predetermined specific voltage impression time, a step of detecting the voltage between the electrodes when the voltage impression time passes, a step of outputting its comparing result by comparing detected detecting voltage with preset threshold value voltage, a step of determining the voltage between the electrodes after performing the respective steps in a plurality of times, and a step of determining whether or not the determined voltage is included in any numeric value range among a plurality of voltage numeric value ranges predetermined in response to a kind of fluid body; and detects a state of filling the fluid body in the filling object space by specifying a kind of fluid body corresponding to the numeric value range of including specified voltage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a filling detection method for detecting a state in which a fluid used in civil engineering construction or building construction is filled in a filling target space, and a computer program used for filling detection.

  Conventionally, when constructing a concrete structure, a fluid such as fresh concrete is placed in a closed space surrounded by a formwork. At this time, depending on the shape of the enclosed space, the flowability of the fresh concrete, the construction method, etc., it was not possible to fill the corner of the enclosed space with fresh concrete, and the mold was removed after the fresh concrete was cured. Sometimes it becomes clear for the first time that the placement was insufficient. In such a case, the fresh concrete will be added again to the part where the fresh concrete has not reached after curing, but when fresh concrete is placed on the concrete after curing, These are not integrated, and a newly added portion is peeled off. Therefore, when placing fresh concrete in the formwork, investigate whether the fresh concrete has spread to every corner of the formwork with the formwork installed before the fresh concrete hardens. is required. For this reason, conventionally, a skilled person hits a formwork with a wooden mallet or the like, and a judgment is made based on experience and intuition by the hitting sound. However, in the conventional placement confirmation method based on experience and intuition by an expert, there is a problem that the difference between the confirmers is large, and even if it is determined that it is filled, it may not actually be filled. there were.

  Recently, a technique for measuring the electrical characteristics using various filling sensors and confirming the filling state has been studied. In Patent Document 1, a sensor composed of one electrode and a pair of thermocouples is used. In addition, a technique for confirming the filling state of the cement kneaded material by measuring electric resistance and temperature has been proposed.

  Prestressed concrete is made of steel that can withstand high tension and gives compressive stress to the concrete, resulting in significantly improved bending strength compared to conventional reinforced concrete. Bridges, building structures, various tanks, disaster prevention equipment It is used for such as.

  The prestressed concrete can be produced by applying a tension to the steel material in advance and placing the concrete in advance. After the concrete has hardened, the tension is released and compressive stress is introduced into the concrete. There is a post-tension system in which concrete is placed after the sheath pipe is placed, and the steel material passed through the sheath pipe is tensioned after the concrete is hardened to introduce compressive stress into the concrete.

  In the post-stressed prestressed concrete, the grout material is filled in the sheath tube for the purpose of integrating the steel material with the concrete and for preventing the steel material from being damaged by corrosion or the like. However, if there is an unfilled portion of the grout material in the sheath tube, chloride ions will enter the case of water and oxygen, as well as the case of structures near the coast and the case where antifreeze is used, and the steel material will corrode for a long period of time. The load-bearing performance of prestressed concrete may be greatly reduced. Therefore, in this construction method, it is necessary to distribute the grout material throughout the sheath tube.

  Conventionally, as a method for confirming the filling of the grout material, it has been estimated from a method of directly confirming the discharge of the grout material from the air discharge port installed on the opposite side of the grout material inlet, and a void ratio in the sheath tube. There are a method for estimating the filling rate from a comparison between the amount of voids to be injected and the amount of grout material actually injected, and a method for visually checking the filling by providing inspection holes. Among them, the non-destructive inspection methods include a method in which an elastic wave is incident and a reflected wave is received and detected, a method in which an unfilled portion of a grout material is detected by an X-ray transmission method, and an ultrasonic wave is input and a reflected wave There are a method for detecting neutrons, a method for detecting absorption of neutrons, and the like (for example, Patent Documents 2 and 3).

As a method using a sensor, there is a method of checking the filling of a grout material by embedding a sensor connected with a conductive cord extending to the outside of concrete (for example, Patent Document 4). There is also a method of reading information sensed by a sensor externally by using a cordless communication technique (for example, Patent Document 5 and Patent Document 6). This method is a method in which internal information of a concrete structure is sensed by a sensor embedded therein, the sensed information is read by a reader by wireless communication, and an internal state is measured.
Japanese Patent No. 2995559 JP-A-10-54140 JP 2001-241187 A JP-A-10-231520 JP 2001-201373 A JP 2003-107030 A

  However, any of the methods of detecting the inside of concrete using elastic waves, ultrasonic waves, X-rays or neutrons has low accuracy and it is difficult to determine whether the grout material is filled or not. Moreover, these methods are complicated.

  Also, in the method of extending the conductive cord from the sensor embedded inside to the outside of the concrete, the conductive cord or the contact surface between the conductive cord and the concrete can be a path for corrosion factors of steel materials such as oxygen, water or chloride ions. There is sex. In particular, when a concrete structure is used over a long period of time, a large difference in the durability of the concrete can occur. When considering the durability of concrete over a long period of time exceeding 100 years, it should not be actively adopted.

  In addition, a method for measuring the internal state of a concrete structure with a reader by wireless means is known, but a specific method for detecting the filling of a grout material into a sheath tube for grout construction of a prestressed concrete structure is as follows. Not proposed.

  In addition, when an electrode is inserted into a fluid such as concrete or grout and a voltage is applied between the electrodes, the filling state of the fluid into the formwork or sheath tube is determined from the change in the voltage between the electrodes. As the voltage application time between the electrodes increases, the voltage value between the electrodes gradually increases, and when voltage is applied to the electrodes, electricity is accumulated in concrete, grout, and water. It was confirmed that a stable voltage value could not be obtained because the voltage value between the electrodes gradually increased each time it was repeated. In the former phenomenon, concrete, grout, water, and the like contain various ions regardless of the amount, and the presence of these ions forms an electrostatic double layer on the electrode surface when a voltage is applied to the electrode. As a result, the interelectrode voltage value gradually increases with respect to the voltage application time. The latter phenomenon is caused by the fact that the current flowing between the electrodes is stored in concrete, grout, water or the like.

  Furthermore, in grout filling detection in grout construction with a prestressed concrete structure, there is a problem that when the sensor is embedded in the concrete together with the antenna, the concrete itself absorbs radio waves, so that satisfactory communication sensitivity cannot be obtained. In addition, when the detector that detects the internal state is placed inside the concrete and only the transmitting antenna is installed on the concrete surface, it is necessary to use conductive cords for the detector and the antenna. There is a possibility that it may enter into the concrete and impair the durability of the concrete.

  The present invention has been made in view of such circumstances, and solves the above-described problems, and is applied to a filling target space such as a formwork of a fluid such as concrete or grout in civil engineering construction or construction construction, or a sheath tube. An object of the present invention is to provide a filling detection method and program capable of accurately detecting a filling state by wireless communication without impairing the durability of concrete.

  (1) In order to achieve the above object, the present invention has taken the following measures. That is, the filling detection method according to the present invention is a filling detection method for detecting a state in which a fluid used in civil engineering construction or construction construction is filled in a filling target space using a filling sensor that performs wireless communication with a reader. In step 1 for setting a threshold voltage in the filling sensor, a voltage is applied to a pair of electrodes of the filling sensor in which a resistance element is inserted between the electrodes for a predetermined voltage application time. Comparing the detected voltage with the threshold voltage set in step 1, and comparing the detected result with step 2 for detecting the voltage between the electrodes when the voltage application time has elapsed. Step 4 for outputting, Step 5 for estimating the voltage between the electrodes after performing each step from Step 1 to Step 4 a plurality of times, and the estimated voltage Step 6 for determining which voltage range is included in a plurality of voltage ranges predetermined according to the filling state of the fluid, and corresponding to the voltage range including the estimated voltage The filling state of the fluid to be filled is detected by specifying the filling state of the fluid to be detected.

  Thus, since a voltage is applied to a pair of electrodes in which a resistance element is inserted between the electrodes, it is possible to accurately detect the electrical characteristics between the electrodes. That is, if a voltage is applied between the electrodes, charge accumulates in the fluid that is in contact with the electrodes, that is, the fluid that is filled in the space to be filled, which affects the detection result. By inserting the element, the charge accumulated in the measurement object (fluid) in the resistance element is consumed as Joule heat, and the charge can be removed. As a result, it is possible to accurately detect the electrical characteristics between the electrodes. In addition, since the detection voltage is compared with a preset threshold voltage, the circuit configuration can be simplified, and the power consumption of the filling sensor can be kept low. Even if the circuit configuration is simplified by applying a voltage between the electrodes, detecting the voltage between the electrodes, and comparing the detected voltage with a preset threshold voltage multiple times. It becomes possible to improve detection accuracy. In addition, since the reader and the filling sensor communicate wirelessly, the invasion of corrosion factors caused by pulling out the lead wires to the outside of the structure as in the past can be avoided, improving the durability of the structure. It becomes possible to make it.

  (2) Further, in the filling detection method according to the present invention, in the second and subsequent steps 1, when the threshold voltage is set again, the threshold voltage is reset based on the previously set threshold voltage and the result of the detection voltage. It is set, and each step from the step 2 to the step 4 is executed based on the threshold voltage after the resetting.

  Thus, after the threshold voltage is initially set, the threshold voltage is reset based on the previously set threshold voltage and the result of the detection voltage when the threshold voltage is set again in Step 1 after the second time. Thus, the detection accuracy can be increased. For example, if the detected voltage detected last time is larger than the previously set threshold voltage as a result of comparison with the previously set threshold voltage, it is reset to a value larger than the previously set threshold voltage, and the previously set threshold voltage is set. Is smaller than the previously set threshold voltage, the detection voltage converges to a constant voltage value each time the number of detections is increased. As a result, since the detection voltage approaches the actual voltage value, it is possible to specify what kind of fluid is in contact with the electrodes, and it is possible to accurately estimate the voltage between the electrodes. .

  (3) Further, in the filling detection method according to the present invention, in the second and subsequent steps 2, the voltage application time is changed to a voltage application time different from the previous voltage application time, and the pair of electrodes is applied. A voltage is applied over a constant voltage application time after the change, and each of the steps 3 and 4 is executed based on the constant voltage application time after the change.

  As described above, since the voltage application time is changed, it is possible to make a determination in consideration of the effect of charge accumulation in the fluid in contact with the electrode. For example, when the fluid in contact with the electrode is air, the detection voltage takes a value very close to the applied voltage regardless of the voltage application time because air is close to insulation. When the fluid in contact with the electrode is a grout to be filled, the detected voltage is always relatively lower than that of tap water regardless of the voltage application time because the conductivity is higher than that of tap water. When the fluid in contact with the electrode is tap water, the detection voltage takes a relatively lower value than air but takes a relatively higher value than grout. Since tap water and grout contain various electrolytes regardless of the amount, an electrostatic double layer is formed on the electrode surface, so that the detection voltage gradually increases as the voltage application time to the electrode is long. is there. From such characteristics, it is possible to specify what the fluid is in contact with the electrode.

  (4) Further, when the program according to the present invention is loaded into a computer provided in the reading device, the reading device performs wireless communication with the filling sensor, and the fluid used in civil engineering or construction work is filled. A program for detecting a state in which a target space is filled, wherein a process A for setting a threshold voltage for a comparison circuit of the filling sensor and a resistance element between electrodes for a voltage application circuit of the filling sensor The voltage application time for the pair of electrodes of the filling sensor into which the voltage is inserted is applied to the voltage detection circuit of the filling sensor and the processing B for applying a voltage over a predetermined constant voltage application time. The process C for detecting the voltage between the electrodes when it has elapsed, the detected voltage detected by the comparison circuit of the filling sensor, and the threshold voltage set in the process A And a process D for outputting the comparison result to the reading device, and a plurality of processes from the processing A to the processing D are executed a plurality of times, and then the determination circuit provided in the reading device is used. The voltage between the electrodes is estimated, and the estimated voltage is determined to be included in a voltage range among a plurality of voltage ranges predetermined according to the filling state of the fluid, The computer executes a series of processes including a process E for detecting a filling state of the fluid into the space to be filled by specifying a filling state of the fluid corresponding to a range including the estimated voltage. It is characterized by being configured as an instruction group to obtain.

  Thus, since a voltage is applied to a pair of electrodes in which a resistance element is inserted between the electrodes, it is possible to accurately detect the electrical characteristics between the electrodes. That is, if a voltage is applied between the electrodes, charge accumulates in the fluid that is in contact with the electrodes, that is, the fluid that is filled in the space to be filled, which affects the detection result. By inserting the element, the charge accumulated in the measurement object (fluid) in the resistance element is consumed as Joule heat, and the charge can be removed. As a result, it is possible to accurately detect the electrical characteristics between the electrodes. In addition, since the detection voltage is compared with a preset threshold voltage, the circuit configuration can be simplified, and the power consumption of the filling sensor can be kept low. Even if the circuit configuration is simplified by applying a voltage between the electrodes, detecting the voltage between the electrodes, and comparing the detected voltage with a preset threshold voltage multiple times. It becomes possible to improve detection accuracy. In addition, since the reader and the filling sensor communicate wirelessly, the invasion of corrosion factors caused by pulling out the lead wires to the outside of the structure as in the past can be avoided, improving the durability of the structure. It becomes possible to make it.

  (5) In the program according to the present invention, the second and subsequent processing A is performed based on the previously set threshold voltage and the result of the detection voltage when the threshold voltage is set again for the comparison circuit. The threshold voltage is reset, and each process from the process B to the process D is executed based on the threshold voltage after the reset.

  Thus, after the threshold voltage is initially set, the threshold voltage is reset based on the previously set threshold voltage and the detection voltage when setting the threshold voltage again in the second and subsequent processing A. Thus, the detection accuracy can be increased. For example, if the detected voltage detected last time is larger than the previously set threshold voltage as a result of comparison with the previously set threshold voltage, it is reset to a value larger than the previously set threshold voltage, and the previously set threshold voltage is set. Is smaller than the previously set threshold voltage, the detection voltage converges to a constant voltage value each time the number of detections is increased. As a result, since the detection voltage approaches the actual voltage value, it is possible to specify what kind of fluid is in contact with the electrodes, and it is possible to accurately estimate the voltage between the electrodes. .

(6) Further, in the program according to the present invention, the process B for the second and subsequent times changes the voltage application time in the voltage application circuit to a voltage application time different from the previous voltage application time, and A voltage is applied to the electrode over a fixed voltage application time after the change,
The processes C and D are performed based on the constant voltage application time after the change.

  As described above, since the voltage application time is changed, it is possible to make a determination in consideration of the effect of charge accumulation in the fluid in contact with the electrode. For example, when the fluid in contact with the electrode is air, the detection voltage takes a value very close to the applied voltage regardless of the voltage application time because air is close to insulation. When the fluid in contact with the electrode is a grout to be filled, the detected voltage is always relatively lower than that of tap water regardless of the voltage application time because the conductivity is higher than that of tap water. When the fluid in contact with the electrode is tap water, the detection voltage takes a relatively lower value than air but takes a relatively higher value than grout. Since tap water and grout contain various electrolytes regardless of the amount, an electrostatic double layer is formed on the electrode surface, so that the detection voltage gradually increases as the voltage application time to the electrode is long. is there. From such characteristics, it is possible to specify what the fluid is in contact with the electrode.

  According to the present invention, since a voltage is applied to a pair of electrodes in which a resistance element is inserted between the electrodes, it is possible to accurately detect electrical characteristics between the electrodes. That is, if a voltage is applied between the electrodes, charge accumulates in the fluid that is in contact with the electrodes, that is, the fluid that is filled in the space to be filled, which affects the detection result. By inserting the element, the charge accumulated in the measurement object (fluid) in the resistance element is consumed as Joule heat, and the charge can be removed. As a result, it is possible to accurately detect the electrical characteristics between the electrodes. In addition, since the detection voltage is compared with a preset threshold voltage, the circuit configuration can be simplified, and the power consumption of the filling sensor can be kept low. Even if the circuit configuration is simplified by applying a voltage between the electrodes, detecting the voltage between the electrodes, and comparing the detected voltage with a preset threshold voltage multiple times. It becomes possible to improve detection accuracy. In addition, since the reader and the filling sensor communicate wirelessly, the invasion of corrosion factors caused by pulling out the lead wires to the outside of the structure as in the past can be avoided, improving the durability of the structure. It becomes possible to make it.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a filling sensor according to the present embodiment. In the filling sensor 1, the pair of electrodes 10a and 10b are in contact with the fluid in the filling target space. A resistance element 11 is provided in parallel between the electrodes 10a and 10b. Thus, since the resistance element 11 is inserted between the electrodes 10a and 10b, it is possible to accurately detect the electrical characteristics. That is, when a voltage is applied between the electrodes 10a and 10b, charge accumulates in the sample in contact with the electrodes, that is, the fluid filled in the filling target space, which affects the detection result. By inserting the resistance element into the resistor, the charge accumulated in the measurement object in the resistance element is consumed as Joule heat, and the charge can be removed. As a result, it is possible to accurately detect the electrical characteristics between the electrodes. Here, since the resistance element 11 is inserted in parallel with the measurement object with respect to the circuit formed by the electrodes 10a and 10b, the measurement object, and the resistance element 11, the charge accumulated in the measurement object is converted into Joule heat. In order to effectively consume, it is preferable that the resistance value is small. However, if the resistance value of the resistance element 11 is too small, there will be no difference from the resistance of concrete or grout, and the difference between the voltage values between the electrodes shown in air, water, concrete or grout will be small and can be identified. It becomes difficult. On the other hand, when the resistance value of the resistance element 11 is too large, it takes a long time to consume the charge accumulated in the measurement object as Joule heat, and it cannot be accurately detected. Therefore, for example, considering that the resistivity of the saturated calcium hydroxide aqueous solution is 50 to 300 Ωcm and the resistivity of water is 2 to 25 kΩcm, the resistance value of the resistance element 11 is 1 kΩ to 1 MΩ. Is preferred.

  The interface circuit 12 is a circuit that connects the electrodes 10 a and 10 b and the RFID IC 13. The RFID IC 13 includes a detection circuit 13a and a wireless communication circuit 13b. The detection circuit 13a applies a voltage to the electrodes 10a and 10b to detect electrical characteristics between the electrodes 10a and 10b. The electrical characteristics include voltage (potential difference) between the electrodes 10a and 10b, electrical resistance, impedance, capacitance, and the like, and these can be detected. In the present embodiment, the voltage between the electrodes 10a and 10b is detected. The wireless communication circuit 13b wirelessly transmits the detection result of the detection circuit 13a to the reading device via the antenna 14.

  FIGS. 2A and 2B are diagrams showing the two-dimensional shape of the electrode. As shown in FIG. 2, the electrodes 10a and 10b have a two-dimensional uneven portion. In FIG. 2A, electrodes 10a and 10b each having a rectangular wave-shaped uneven portion 15 are arranged so as to mesh with each other, and a lead wire 16 is added to each. In FIG. 2B, the electrodes 10a and 10b having the rectangular wave-shaped concavo-convex portions 17 are arranged so as to face each other, and a lead wire 16 is added to each of them. The shape of the concavo-convex portion of the electrode can be a sawtooth shape, a staggered shape, a spiral shape, or the like, as well as a rectangular wave shape as illustrated. By making the concave and convex portions of the electrode into such a shape, even if the area of the electrode itself in contact with the fluid is the same, the entire area where the electrodes are arranged as shown in FIG. 2 is increased. Therefore, there is less concern about air remaining in the electrode part. In addition, since the entire electrode portion is larger than the case where the two electrodes are formed in a flat shape or a rod shape, it is possible to detect the filling state sensitively even if the electrode portion is slightly contacted with concrete or grout. It becomes possible. In addition, as an outer dimension of the electrode, for example, a square or rectangular shape within a range of about 5 mm to 25 mm such as about 5 mm × 5 mm, 10 mm × 10 mm, 15 mm × 15 mm, 20 mm × 20 mm, 25 mm × 25 mm can be used. .

  In addition, by arranging the rectangular or sawtooth two-dimensional concavo-convex portions to mesh with each other, it is possible to accurately detect the filling status even when concrete or grout flows from any direction of the electrode portion. it can. Further, it is possible to reduce the size of the electrode and to detect a weak change in electric resistance value. As described above, each electrode may be formed by connecting a plurality of metal plates with metal wires or the like in addition to the end portions of the electrodes having a rectangular wave shape or a sawtooth wave shape. By configuring the electrode in this way, the measurement object (fluid) such as grout is more likely to come into contact with another metal plate even if it does not come into contact with one of the metal plates. It becomes possible to improve.

As for the size of the electrode, as the electrode area increases, the liquid resistance between the electrodes decreases, and conversely, the capacitance increases, and the polarization resistance of the electrode varies depending on the environmental conditions where the electrodes are placed. It is known. For this reason, in order to detect the filling state of concrete or grout more accurately, the examination of the electrode size is important. In the case of FIG. 1, the region occupied by the pair of electrodes 10a and 10b is, for example, about 400 mm ² .

  In addition, the pair of electrodes 10a and 10b may be formed of the same metal or may be formed of different metals. When different metals are used for the electrodes, the potential difference generated between the electrodes varies depending on the combination of the different metals and the difference in the substances existing between the electrodes. When different metals are used, a so-called “galvanic battery” is formed, so that a potential difference occurs as a natural phenomenon without applying a voltage between the electrodes. As a result, no power is consumed during detection, so that power can be used for wireless communication between the sensor and the reading device, and the communication distance can be relatively increased.

  When using dissimilar metals, it is better to combine metals that increase the potential difference between the electrodes as much as possible.For example, in gold and aluminum, gold and zinc, aluminum and zinc are very strong in strong alkali. Since it is easy to dissolve, it can be used to detect the filling status immediately after filling concrete and grout. However, in the completion inspection conducted several months after the completion of construction, the electrode dissolves and disappears to check the filling status. May not be possible. Moreover, since hydrogen gas is generated when dissolved in alkali, this hydrogen gas may weaken the PC steel (hydrogen embrittlement). On the other hand, the combination of metals with a relatively small potential difference has the advantage that the difference in potential difference between water and concrete or water and grout is small, but the measurement error is also small.

  As described above, when the pair of electrodes 10a and 10b is formed of different kinds of metals, it is necessary to determine the combination of the metals by sufficiently considering the above-described problems. Specific examples of combinations of different metals are as follows. That is, the electrode material combination may be anything as long as the difference between the electromotive force in the alkaline substance and the electromotive force in the water is slight, such as iron and aluminum, iron and stainless steel, iron and zinc, iron and gold, iron And niobium, alloys of iron and various metals, carbon and silver, carbon and titanium, carbon and copper, carbon and tungsten, carbon and molybdenum, carbon and stainless steel, carbon and gold, carbon and brass, carbon and tin, carbon and various metals Alloys of titanium, gold, titanium and various metals, silver and copper, silver and molybdenum, silver and stainless steel, silver and tin, silver and various metal alloys, aluminum and carbon, aluminum and silver, aluminum and nickel, aluminum And tungsten, aluminum and molybdenum, aluminum and stainless steel, copper and various metal alloys, nickel and brass, nickel and various metals , Tungsten and niobium, tungsten and various alloys of metals, molybdenum and various alloys of metals, stainless steel and brass, such as gold and tin and the like.

  Next, the detection circuit 13a in the RFID IC 13 shown in FIG. 1 will be described. FIG. 3 is a block diagram showing a schematic configuration of the detection circuit 13a. In the detection circuit 13a, the voltage application circuit 30a applies a voltage between the pair of electrodes 10a and 10b over a predetermined voltage application time. This voltage application time can be changed by control from an external reader. The voltage detection circuit 30b detects the voltage between the pair of electrodes 10a and 10b when the voltage application time in the voltage application circuit 30a has elapsed.

The comparison circuit 30c compares a preset threshold voltage with a detection voltage to determine whether the input voltage to the comparison circuit 30c is small or large. An operation of determining whether the voltage value between the electrodes is larger or smaller than a preset threshold voltage when a predetermined voltage is applied to the pair of electrodes 10a and 10b by the voltage application circuit 30a, using the comparison circuit 30c, Measure multiple times by changing the threshold voltage. This makes it possible to accurately determine the voltage value between the electrodes. Note that the resolution of the comparison circuit 30c can be increased by increasing the number of measurements of the comparison circuit 30c. For example, the applied voltage Vin, when the number of measurements 8 times the resolution of the comparison circuit 30c becomes Vin / ^{2 8.}

  These voltage application circuit 30a, voltage detection circuit 30b, and comparison circuit 30c are connected to a control line 30d, and can transmit and receive data to and from each other.

  The voltage application circuit 30a, the voltage detection circuit 30b, and the comparison circuit 30c apply various voltages necessary for applying a predetermined voltage between the electrodes 10a and 10b and measuring electrical characteristics (voltage) between the electrodes 10a and 10b. A high output current circuit, an inverting amplifier circuit, an in-phase amplifier circuit, a voltage follow circuit, an integral amplifier circuit, a comparison operation circuit, a comparison operation circuit with hysteresis characteristics, a multivibrator circuit, a current-voltage conversion circuit, and the like. Various resistance elements, capacitors, coils, and the like are incorporated so as to constitute these.

  In FIG. 1, the radio communication circuit 13b of the RFID IC 13 constituting the radio communication unit 3 includes a modulation circuit, a charging / power supply unit, a memory, and the like. This power supply unit may be of a type equipped with a battery, or may be of a so-called battery-less type, that is, having a power storage function and temporarily storing an induced voltage due to electromagnetic waves supplied from the outside. good. A memory included in the wireless communication circuit 13b includes a ROM that stores an operating system that performs overall control, an EEPROM that stores programs for detecting data rewriting and the state of structures, and a RAM that records detected information. Etc. An ID number of the sensor may be mounted on the memory, or information on the position where the structure is embedded is written in the RAM from the reading device, and the information may be read by the reading device together with the information detected by the sensor.

  The antenna 14 constituting the wireless communication unit 3 in FIG. 1 is made of metal, carbon fiber, ferrite, or the like, and is formed on a hollow winding, a magnetic winding, or a substrate using a printing technique. It is desirable to use these materials, and these materials may be sandwiched between films such as PET, and the shape may be molded into an appropriate shape such as a ring shape, a rod shape, or a disk shape.

  The filling sensor according to the present embodiment configured as described above is installed inside a concrete structure or the like. For example, when looking at the filling state of the cast concrete, it is desirable that the mounting position of the filling sensor is in the cover concrete. When attached inside the cover concrete, the electromagnetic wave emitted from the reading device is absorbed by the reinforcing bar, and the communication distance between the filling sensor and the reading device is greatly reduced or communication is not possible. However, when the filling sensor is arranged inside the reinforcing bar, communication between the filling sensor and the reading device can be performed by using the reinforcing bar itself as an antenna.

  The following cases are also conceivable as methods for attaching the filling sensor. Only the electrode part is attached to the place where the filling state is to be detected, the detection part 2 and the wireless communication part 3 integrated (hereinafter referred to as a tag) are attached outside the reinforcing bar, and the electrode part and the tag are connected with lead wires. It is also possible to adopt an attachment method for connection. With this attachment method, there is no restriction on the location where the electrode portion is attached.

  FIG. 4 is a block diagram showing a schematic configuration of the reading apparatus according to the present embodiment. The reading device 40 performs wireless communication with the filling sensor by the antenna 41. The controller 42 modulates and demodulates data in the wireless communication circuit 42a. In the sensor control circuit 42b, the threshold voltage in the comparison circuit 30c of the filling sensor 1 is reset, and the voltage application time in the voltage application circuit 30a is changed. Further, in the determination circuit 42c, the voltage between the electrodes in the filling sensor 1 is estimated, and the estimated voltage falls in any numerical value range among a plurality of voltage numerical ranges determined in advance according to the type of fluid. Determine whether it is included. And the condition where the fluid was filled in the filling object space is detected by specifying the type of the fluid corresponding to the numerical range including the specified voltage. The control unit 42 includes a memory, a CPU, and a power supply unit for supplying power. Further, if necessary, information from the filling sensor 1 may be output directly to other devices via the interface circuit 43 by performing data processing. In this case, the reading device 40 does not need to include the determination circuit 42c in the control unit 42, and may operate the determination circuit in another device.

  Next, the sheath tube to which the filling sensor according to this embodiment is attached will be described. FIG. 5 is a diagram showing the appearance of the sheath tube. The sheath tube 50 is used for grout construction of a prestressed concrete structure, and is not limited to a metal one but may be a commercially available one made of resin. When a hole for attaching a sensor is made in a steel sheath tube, the hole cannot be made cleanly depending on the state of the tool used. Moreover, since a burr | flash remains inside the hole after drilling, it is preferable that the sheath tube 50 is made of resin. The resin sheath tube has an advantage that it is easy to process because there is no problem that burrs remain inside the hole opened with a tool or the like. In FIG. 5, the sheath tube 50 is provided with a sensor attachment portion 51 for attaching a filling sensor. The sensor mounting portion 51 protrudes in a rectangular shape from the inner surface of the sheath tube 50 toward the outer surface, and a rectangular recess is formed when viewed from the inner surface side. When the electrode is attached to the sheath tube 50, it is necessary to keep the electrode and the PC steel material at a certain distance, for example, an interval of 1 to 10 mm so that the PC steel material and the electrode do not contact each other. At least the distance between the electrode and the PC steel must be greater than the electrode spacing. This is because when the distance between the electrode and the PC steel material is narrower than the electrode interval, a current that should flow between the electrodes may flow into the PC steel material.

  FIG. 6 is a view showing an appearance of a sheath tube joint member to which the filling sensor according to the present embodiment is attached. The sheath pipe joint member 60 is for connecting sheath pipes used for grout construction of a prestressed concrete structure. The sheath pipe joint member is not limited to a metal but may be a commercially available product made of resin. It is necessary to secure at least 1 cm to 10 cm at the connection portion between the sheath tube joint member and the sheath tube. This is because when the overlapping length of the connecting portions is short, the joint member and the sheath tube may be separated. In FIG. 6, the sheath pipe joint member 60 is provided with a sensor attachment portion 61 for attaching a filling sensor. Similar to the sensor attachment portion 51 of the sheath tube 50 shown in FIG. 5, the sensor attachment portion 61 protrudes in a rectangular shape from the inner surface of the sheath tube joint member 60, and has a rectangular depression when viewed from the inner surface side. Is formed.

  In the sheath tube shown in FIG. 5 and the sheath tube joint member shown in FIG. 6, the filling sensor is attached to the sensor attachment portions 51 and 61 as shown in FIG. In FIG. 7A, in the sensor attachment portions 51 and 61, for example, a pair of electrodes obtained by gold-plating nickel on a material having an electrode width of 10 mm, a length of 10 mm, and an electrode interval of 10 mm are attached. In FIG. 7B, in the sensor attachment portions 51 and 61, for example, a pair of electrodes 10a and 10b having a rectangular wave-shaped uneven portion 15 are arranged so as to mesh with each other. And parts other than the electrode of a filling sensor are attached so that the sensor attaching parts 51 and 61 may be covered.

  Next, the operation of the filling detection method according to the present embodiment configured as described above will be described. FIG. 8 is a sequence chart showing an outline of the filling detection method according to the present embodiment. Here, a method for determining whether or not a fluid such as concrete, grout, water, or air exists between a pair of electrodes will be described. In FIG. 8, in the reading device 40, the program loaded from the memory is executed by the CPU. Then, an instruction is given to set a threshold voltage in the comparison circuit 30c of the filling sensor 1 (step S1). This command is transmitted from the reading device 40 to the filling sensor 1 as a radio signal. The filling sensor 1 sets a threshold voltage instructed by the reading device to the comparison circuit 30c based on the received wireless signal (step S2). In this case, since the threshold voltage is set first, the threshold voltage set at this time becomes an initial set value. Next, in the reading device 40, the voltage application circuit 30a in the filling sensor 1 instructs the voltage to be applied to the pair of electrodes 10a and 10b (step S3).

  In the filling sensor 1, the voltage application circuit 30a applies a voltage to the pair of electrodes 10a and 10b over a voltage application time (step S4). The voltage application time is determined in advance. For example, the voltage is applied in the range of 0.1 ms to 15.0 ms. In the filling sensor 1, the voltage detection circuit 30b detects the voltage between the pair of electrodes 10a and 10b after the end of the voltage application time (step S5). Then, the comparison circuit 30c compares the threshold voltage set in step S2 with the detection voltage detected in step S5, and wirelessly transmits the comparison result to the reading device (step S6).

  In the present embodiment, the operations from step S1 to step S6 are performed a plurality of times, for example, eight times. In the reading device 40, after step S6, 1 is added to N (N is a natural number and indicates the number of times the operation from step S1 to step S6 has been performed) (step S7), and N is a predetermined number M ( Here, it is determined whether or not it has reached 8 times (step S8). If N = M is not satisfied, the process proceeds to step S1. In Step 1, since the threshold value is set again after the initial setting, if the previously set threshold voltage is compared with the previously detected threshold voltage, if it is larger than the previously set threshold voltage, the previous setting is performed. If the threshold voltage is reset to a value larger than the previously set threshold voltage, and smaller than the previously set threshold voltage, it is reset to a value smaller than the previously set threshold voltage (step S1). And based on the threshold voltage reset in step S1, each step to step S1 step S8 is performed again.

  As described above, when the threshold voltage is initialized and then the threshold voltage is set again, as a result of comparing the detected voltage detected last time with the previously set threshold voltage, If the threshold voltage is reset to a value larger than the previously set threshold voltage and is smaller than the previously set threshold voltage, the threshold voltage is reset to a value smaller than the previously set threshold voltage. It converges to a constant voltage value. As a result, since the detection voltage approaches the actual voltage value, it is possible to specify what kind of fluid is in contact with the electrode, and it is possible to increase detection accuracy.

  In step S8, if N = M, the voltage between the electrodes is estimated (step S9). That is, since the comparison circuit 30c performs the comparison operation eight times, it is possible to estimate the voltage between the pair of electrodes 10a and 10b.

  FIG. 9 is a diagram illustrating a relationship between time and a voltage between the pair of electrodes 10a and 10b in each fluid of air, tap water, and grout. As shown in FIG. 9, when the fluid is air, since the air is close to insulation, the detection voltage takes a value very close to the applied voltage. When the fluid is grout, the detected voltage is always relatively lower than tap water because the grout has higher conductivity than tap water. When the fluid is tap water, as shown in FIG. 9, it shows a voltage within the range of air and grout. Thereby, what kind of fluid is in contact with the pair of electrodes 10a, 10b can be specified. As a result, it is possible to detect the filling state of the fluid in the space to be filled.

(Modification)
Next, a modification of this embodiment will be described. Here, detection is performed by setting a plurality of threshold voltages in the comparison circuit 30c of the filling sensor 1 and changing the voltage application time in the voltage application circuit 30a. That is, in step S1 shown in FIG. 8, when outputting a threshold voltage setting command, a command for setting a threshold voltage different from the previous threshold voltage is output according to the length of voltage application time. Here, as shown in FIG. 10, two threshold voltages A and B are set. In step S3, the voltage application command is output. For example, the voltage application command is output so that the voltage application time becomes longer as the number of detections increases, so as to change the voltage application time.

  FIG. 10 is a diagram illustrating the relationship between time and the voltage between the pair of electrodes 10a and 10b in each fluid of air, tap water, and grout. Two threshold values, A and B, are set. Based on these threshold values, the detection is performed with the shortest voltage application time in the first detection. In the second, third and fourth times, the voltage application time is gradually increased, and the voltage between the electrodes at the end of the voltage application time is detected.

  According to this modified example, as shown in FIG. 10, when the fluid is air, the air is close to insulation, so that the detected voltage is determined to be higher than the threshold voltages A and B regardless of the voltage application time. Is done. Further, when the fluid is grout, the grout has higher conductivity than tap water, so that the detected voltage is determined to be lower than the threshold voltages A and B regardless of the voltage application time. When the fluid is tap water, the detection voltage is lower than the threshold voltage A when the voltage application time is short, as shown in FIG. However, as the voltage application time is gradually increased, the detection voltage becomes larger than the threshold voltage A and takes a value between the threshold voltages A and B. As the voltage application time is further increased, the detection voltage gradually increases and finally becomes larger than the threshold voltage B. Thereby, what kind of fluid is in contact with the pair of electrodes 10a, 10b can be specified. As a result, it is possible to detect the filling state of the fluid in the space to be filled.

  It has been confirmed that the voltage value between the electrodes after voltage application gradually increases as the application time increases in the course of various studies using the determination method. In addition, when voltage is applied to the electrodes, electricity is accumulated in concrete, grout, and water. Therefore, when the voltage value is determined using the comparison circuit 30c, the voltage value between the electrodes gradually increases. It was confirmed. In the former phenomenon, concrete, grout, water, and the like contain various ions regardless of the amount, and the presence of these ions forms an electrostatic double layer on the electrode surface when a voltage is applied to the electrode. As a result, the interelectrode voltage value gradually increases with respect to the voltage application time. The latter phenomenon is caused by the fact that the current flowing between the electrodes is stored in concrete, grout, water or the like.

  By sufficiently grasping the above two phenomena, it became possible to accurately determine air, water (tap water, mud water, etc.), concrete and grout.

  A specific discrimination method is shown below, but is not limited to this method. That is, the voltage value between the electrodes after a lapse of a certain time after the voltage application to the electrodes is compared with a preset comparison voltage value. Since air is in a state close to insulation, the voltage value between the electrodes shows a value close to the applied voltage.Concrete and grout contain a large amount of various water-soluble salts and show conductivity. Becomes a value close to 0V. Water (tap water, muddy water, etc.) indicates a voltage value within the range of air and concrete or grout. Therefore, when the threshold voltage is set to be an intermediate value between the voltage value shown in the case of concrete or grout and the voltage value shown in the case of water (tap water, muddy water, etc.), the obtained interelectrode voltage is the threshold voltage. When it is smaller than the voltage, it is determined as concrete or grout. If the voltage is higher than the threshold voltage, the threshold voltage is reset so that it is an intermediate value between the voltages of water (tap water, muddy water, etc.) and air, and the resulting interelectrode voltage is reset. When it is smaller than the threshold voltage, it is determined that the water is used. If the obtained interelectrode voltage is higher than the reset threshold voltage, it is determined that the air is air. The determination method is used to determine what the measurement object is. Next, an embodiment showing the result of actually using such a filling sensor will be described.

  4 steel plates (tensile material) of 12S12.7B are arranged in the girders as the length of the girders is 32m, and the sheath tube is a post-tension type T-type prestressed concrete (hereinafter referred to as PC concrete) with a steel outer diameter of 68mm. ) Is an example of detecting grout filling in construction. In the pre-PC concrete designed according to the road bridge specifications, girder reinforcement was performed, followed by the sheath tube. As shown in FIG. 7A, the filling sensor has an electrode width of 10 mm, a length of 10 mm, and an electrode interval of 10 mm, and the material is nickel plated with gold. Five filling sensors of the present invention were attached to each of the four sheath tubes arranged in the beam. The attachment was made by making a hole in the sheath tube so that the electrode was inside the sheath. The detection unit and the wireless communication unit include an RFID chip including a sensor, modulation / demodulation, CPU, memory, sensor control unit, an antenna, and a power storage function. For communication between the sensor and the reader, 13.56 MHz Frequency was used.

  After installing the filling sensor, concrete was cast and steam curing was performed to remove the mold, and curing was performed for 2 weeks, and PC steel was inserted and strained. The grout used for filling is manufactured using commercially available grout admixtures with water cement ratios of 28%, 35%, 45%, and 55%. The grout of each water cement ratio is placed on four sheath tubes. Injected. Injection is performed from one side of the sheath tube using a grout pump, the injection rate is 10 liters / minute, and the grout design quantity calculated from the porosity of the sheath tube and the PC steel material and the length of the sheath tube is 2 / 3. After the injection, grout filling was detected using a reader, and after grout hardening, the grout filling condition near the sensor was confirmed by drilling.

  As a result, in the filling detection method of the present invention, in any sheath tube, the grout was filled at three sensor positions from the injection port, and the grout was not filled at the remaining two positions. This result coincides with the presence or absence of grout filling confirmed by drilling, and it was found that the presence or absence of grout filling of PC concrete can be detected by the system of the present invention.

  The characteristic operation of the present invention as described above is performed by executing a program. That is, when this program is loaded into a computer provided in the reading device 40, the reading device 40 performs wireless communication with the filling sensor 1, and a fluid used in civil engineering or building construction fills the space to be filled. A process A for setting a threshold voltage for the comparison circuit 30 c of the filling sensor 1 and a resistance element inserted between the electrodes for the voltage application circuit 30 a of the filling sensor 1. When the voltage application time has elapsed for the process B for applying a voltage to the pair of electrodes of the filling sensor 1 over a preset constant voltage application time and the voltage detection circuit 30b of the filling sensor 1 A ratio between the detected voltage detected by the process C for detecting the voltage between the electrodes of the charging sensor 1 and the comparison circuit 30c of the filling sensor 1 and the threshold voltage set in the process A Then, after the processing D for outputting the comparison result to the reading device 40 and each processing from the processing A to the processing D are executed a plurality of times, the determination circuit 42c included in the reading device 40 has an electrode The voltage between the two is estimated, and the estimated voltage is included in a plurality of voltage ranges determined in advance according to the filling state of the fluid, and the estimated voltage is included. It is configured as a group of instructions that allow the computer to execute a series of processes including a process E for detecting the filling state of the fluid filling target space by specifying the filling state of the fluid corresponding to the range. . Further, in the process A, when the threshold voltage is initialized for the sensor control circuit 42b of the reading device 40 and then the threshold voltage is set again, the previously detected voltage is compared with the previously set threshold voltage. As a result, if it is larger than the previously set threshold voltage, it is reset to a value larger than the previously set threshold voltage, and if smaller than the previously set threshold voltage, it is set to a value smaller than the previously set threshold voltage. A process of resetting may be further included, and the filling sensor 1 may be caused to execute each process from the process B to the process D again based on the reset threshold voltage. The process B may further include a process of changing the voltage application time in the voltage application circuit 30a with respect to the sensor control circuit 42b of the reading device 40. Based on this, each process from process B to process D may be executed again.

  This program can be obtained in a state of being recorded on a recording medium such as a CD-ROM or a DVD. In addition, such a program is transmitted by a computer as a transmission device via a transmission medium such as a communication network including a public telephone line, a dedicated telephone line, a cable TV line, a wireless communication line, etc. constituting the network. It can also be obtained by receiving the received signal. This signal is a computer data signal embodied in a predetermined carrier wave including a program. At the time of this transmission, it is only necessary to transmit at least a part of the program in the transmission medium. That is, it is not necessary for all data constituting the program to exist on the transmission medium at a time. Further, the transmission method for transmitting a program from the computer includes a case where data constituting the program is transmitted continuously and a case where it is transmitted intermittently.

It is a block diagram which shows schematic structure of the filling sensor which concerns on this embodiment. (A) and (b) are figures which show the two-dimensional shape of an electrode. It is a block diagram which shows schematic structure of a detection circuit. It is a block diagram which shows schematic structure of a reader. It is a figure which shows the external appearance of the sheath pipe | tube with which the filling sensor which concerns on this embodiment was attached. It is a figure which shows the external appearance of the sheath pipe joint member to which the filling sensor which concerns on this embodiment was attached. It is a figure which shows the electrode attached to the sensor attachment part. It is a sequence chart which shows operation | movement of a reader and a filling sensor. It is a figure which shows the relationship between time and the voltage between a pair of electrodes in each fluid of air, tap water, and grout. It is a figure which shows the relationship between time and the voltage between a pair of electrodes in each fluid of air, tap water, and grout.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Filling sensor 2 Detection part 3 Radio | wireless communication part 10a, 10b Electrode 11 Resistance element 12 Interface circuit 13a Detection circuit 13b Wireless communication circuit 14 Antenna 15 Irregularity part 16 Lead wire 17 Irregularity part 30a Voltage application circuit 30b Voltage detection circuit 30c Comparison circuit 30d Control line 40 Reading device 41 Antenna 42 Control unit 42a Wireless communication circuit 42b Sensor control circuit 42c Determination circuit 43 Interface circuit 50 Sheath tube 51 Sensor attachment portion 60 Sheath tube joint member 61 Sensor attachment portion

Claims (6)

A filling detection method for detecting a state in which a fluid used in civil engineering construction or building construction is filled in a filling target space using a filling sensor that performs wireless communication with a reader,
Setting a threshold voltage for the filling sensor;
Applying a voltage over a predetermined voltage application time to a pair of electrodes of the filling sensor in which a resistance element is inserted between the electrodes; and
Detecting a voltage between the electrodes when the voltage application time has elapsed; and
Step 4 for comparing the detected detection voltage with the threshold voltage set in Step 1 and outputting the comparison result;
Step 5 for estimating the voltage between the electrodes after performing each step from Step 1 to Step 4 a plurality of times;
And at least a step 6 for determining which voltage range is included in a plurality of voltage ranges that are determined in advance according to the filling state of the fluid.
A filling detection method comprising: detecting a filling state of the fluid in the filling target space by specifying a filling state of the fluid corresponding to a voltage range including the estimated voltage. In Step 1 after the second time, when setting the threshold voltage again, the threshold voltage is reset based on the previously set threshold voltage and the result of the detection voltage,
The filling detection method according to claim 1, wherein the steps from Step 2 to Step 4 are executed based on the reset threshold voltage. In step 2 after the second time, the voltage application time is changed to a voltage application time different from the previous voltage application time, and the voltage is applied to the pair of electrodes over the constant voltage application time after the change. Apply
3. The filling detection method according to claim 1, wherein the steps 3 and 4 are executed based on the constant voltage application time after the change. A program for detecting a situation in which a fluid used in civil engineering or building construction is filled in a filling target space by being loaded into a computer provided in the reading device so that the reading device performs wireless communication with a filling sensor. There,
Processing A for setting a threshold voltage for the comparison circuit of the filling sensor;
A process B for applying a voltage over a predetermined voltage application time to a pair of electrodes of the filling sensor in which a resistance element is inserted between the electrodes, with respect to the voltage application circuit of the filling sensor;
A process C for detecting a voltage between the electrodes when the voltage application time has elapsed with respect to the voltage detection circuit of the filling sensor;
A process D for comparing the detected detection voltage with the threshold voltage set in the process A to the comparison circuit of the filling sensor and outputting the comparison result to the reading device;
After each processing from the processing A to the processing D is executed a plurality of times, the voltage between the electrodes is estimated with respect to the determination circuit provided in the reading device, and the estimated voltage is filled with the fluid. By determining which voltage range is included in a plurality of voltage ranges predetermined according to the situation, by specifying the filling state of the fluid corresponding to the range that includes the estimated voltage, A program comprising a series of processes including a process E for detecting a filling state of the fluid into the space to be filled as an instruction group that can be executed by a computer. In the second and subsequent processing A, when the threshold voltage is set again for the comparison circuit, the threshold voltage is reset based on the previously set threshold voltage and the result of the detection voltage,
5. The program according to claim 4, wherein each process from the process B to the process D is executed based on the threshold voltage after the resetting. In the second and subsequent processing B, the voltage application time in the voltage application circuit is changed to a voltage application time different from the previous voltage application time, and a constant voltage application after the change is applied to the pair of electrodes. Applying voltage over time,
6. The program according to claim 4, wherein the processes C and D are executed based on the fixed voltage application time after the change.

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