Ground anchor with sensor and grout filling method using the same

Abstract

To easily and accurately fill a filling space between a drilled hole and a ground anchor with a sensor with a planned amount of grout by inserting the ground anchor with the sensor into the drilled hole bored in a slope face.SOLUTION: A ground anchor 300 with a sensor uses a PC steel material as an example of a tensioning material, fills a part between a filling space 310 provided in a tension force application object with grout and the PC steel material in a sheath pipe 304, and tensions and fixes the PC steel material after grout curing to reinforce the tension force application object. The ground anchor 300 with the sensor is provide with at least one light intensity detection sensor (joined part 230 thereof) which uses a change made in light intensity in accordance with a contact medium. Thus, a grout filling state of the filling space 310 can be determined irrespective of the presence / absence of water in the filling space 310.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a sensor-equipped ground anchor structure and a grout filling method using the same, and more particularly, to a sensor-equipped ground anchor and a grout filling method using the same that can easily and accurately grasp the amount of grout to be filled when, for example, inserting the sensor-equipped ground anchor into a drilled hole in a slope (an object to be tensioned) and filling the filling space between the drilled hole and the sensor-equipped ground anchor (tensioning member) with grout. In this invention, the tensioning members used in the sensor-equipped ground anchor include prestressing steel, FRP (fiber reinforced plastic), synthetic fiber, etc. Furthermore, the prestressing steel includes prestressing steel wires, prestressing steel rods, prestressing steel strands, and prestressing steel members the outer surface of which is coated with a resin (such as epoxy). [Background technology]

[0002] Slopes, bridge abutments, retaining walls, quay structures, and other buildings (tensioned objects) may need to be reinforced due to disasters (earthquakes, wind and flood damage, etc.) or deterioration over time. For example, a ground anchor method is known for preventing surface collapse or bedrock collapse by providing the tensile force applied to tensioning members made of prestressing steel strands through the adhesion resistance between the tensioning members (prestressing steel strands) and grout. In such cases, after inserting the ground anchor into the drilled hole, grout is filled into the space between the drilled hole in the object to be tensioned and the tensioning member (e.g., prestressing steel). After the grout hardens, it tensions the prestressing steel strands, securing them in place and reinforcing the object to be tensioned. The amount of grout must be sufficient to fill the required amount.

[0003] A technique for filling a filling space with grout without any shortages in this way is disclosed in Japanese Patent Laid-Open No. 7-317215 (Patent Document 1). Patent Document 1 discloses a method for checking the status of grout injection into a PC member in real time, and this grout injection status checking method is characterized by disposing a linear temperature sensor in a grout hole, making the temperature of the grout material filled in this hole slightly different from the temperature inside the hole when it is not filled, and observing the change in measurement by the linear temperature sensor on a monitor, and characterized in that the linear temperature sensor is an optical fiber temperature radar.

[0004] According to this method for checking the status of grout injection, when grout material is injected into a grout hole, the temperature of the filled area changes, causing a change in the measurement value of the linear temperature sensor. Therefore, by observing this change in measurement on a monitor, the flow rate and current position of the grout can be confirmed, and it is also possible to issue a warning if the flow rate falls below a certain value. In addition, since the linear temperature sensor uses optical fiber temperature radar, it is easy to set up, as it only requires placing an optical fiber inside the grout hole, and it does not interfere with the adhesion between the grout and the prestressing steel. Furthermore, after measurement, the optical fiber can be removed and reused, which reduces costs. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-317215 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the grout injection status confirmation method disclosed in the above-mentioned Patent Document 1, the grout hole into which the grout is filled is merely a sheath. On the other hand, in the present invention, the grout hole (grout filling space) into which the grout is filled is, for example, a drilled hole opened in the slope face, and since there is a possibility that groundwater (sometimes simply referred to as water) may be present in the grout filling space, even if the grout is temperature-controlled, there is a possibility that groundwater that comes into contact with the grout will be erroneously detected as grout. Furthermore, the grout injection status confirmation method disclosed in the above-mentioned Patent Document 1 cannot confirm the hardening status of the grout.

[0007] The present invention was developed in consideration of the above-mentioned problems of the prior art, and its purpose is to provide a sensor-equipped ground anchor and a grout filling method using the same that can easily and accurately grasp the amount of grout to be filled when inserting the sensor-equipped ground anchor into a hole opened in an object to be tensioned (for example, a slope) and filling grout into the filling space between the hole and the sensor-equipped ground anchor (a prestressing steel member, which is an example of a tendon).A further purpose of the present invention is to provide a sensor-equipped ground anchor and a grout filling method using the same that can easily check the hardening state of the grout after filling. [Means for solving the problem]

[0008] In order to achieve the above object, the sensor-equipped ground anchor and the grout filling method using the same according to the present invention employ the following technical measures. In other words, the ground anchor with a sensor according to the present invention is a ground anchor with a sensor that fills the space between a filling space provided in an object to be tensioned and a tensioning member with grout, and then tensions and fixes the tensioning member after the grout has hardened, thereby reinforcing the object to be tensioned.It is characterized by having at least one light intensity detection sensor that utilizes the fact that light intensity changes depending on the contact medium, and by being equipped with at least one light intensity detection sensor that utilizes the fact that light intensity changes depending on the contact medium, it is possible to determine the grout filling state in the filling space regardless of whether water is present in the filling space.

[0009] Preferably, the light intensity detection sensor can be configured to be able to distinguish between air, water, and grout.

[0010] More preferably, the light intensity detection sensor can be configured to distinguish between air, water, and grout, as well as between grout at the time of filling and grout after hardening.

[0011] More preferably, the light intensity detection sensor may be integrated with the ground anchor with sensor.

[0012] More preferably, the light intensity of the plurality of light intensity detection sensors is measured with the contact medium being air, water, and grout, and the ratio of the light intensity measured when the contact medium is water to the light intensity measured when the contact medium is air (light intensity ratio (W) = light intensity when in contact with water / light intensity when in contact with air) is taken as the horizontal axis, and the ratio of the light intensity measured when the contact medium is air to the light intensity measured when the contact medium is grout (light intensity ratio (G) = light intensity when in contact with grout / light intensity when in contact with air) is taken as the vertical axis. Based on this, the light intensity ratio (W) when one of the light intensity detection sensors is attached to water can be used as a threshold value, and if the light intensity ratio is equal to or less than the threshold value, the contact medium is determined to be water, and if the light intensity ratio is greater than the threshold value, the contact medium is determined to be grout.

[0013] More preferably, the threshold value can be corrected to a corrected threshold value, and if the value is equal to or less than the corrected threshold value, the contact medium is determined to be water, and if the value is greater than the corrected threshold value, the contact medium is determined to be grout.

[0014] Furthermore, a grout filling method according to another aspect of the present invention is a grout filling method using the above-mentioned sensor-equipped ground anchor, and includes an inserting step of determining the position of the light intensity detection sensor corresponding to the position where grout and / or water is desired to be detected and inserting the sensor-equipped ground anchor together with at least one of the light intensity detection sensors into the drilled hole, and a filling step of filling grout between the filling space and the tendon, wherein in the filling step, grout is filled up to a predetermined position while detecting grout and / or water at the position based on a change in the light intensity detected by the light intensity detection sensor.

[0015] Furthermore, a grout filling method according to yet another aspect of the present invention is a grout filling method using the above-mentioned sensor-equipped ground anchor, and includes an inserting step of determining the position of the light intensity detection sensor corresponding to the position where grout and / or water is to be detected and inserting the sensor-equipped ground anchor together with at least one of the light intensity detection sensors into the drilled hole, and a filling step of filling grout between the filling space and the tendon, wherein in the filling step, grout is filled up to a predetermined position while detecting grout and / or water at the position based on a change in the light intensity ratio based on the light intensity detected by the light intensity detection sensor.

[0016] Preferably, the above-mentioned grout filling method can be configured to further include a determination step of determining, after the filling step, that the grout filled into the filling space has hardened based on a change in the light intensity detected by the light intensity detection sensor, using the light intensity detection sensor that can distinguish between air, water, and grout, as well as between grout at the time of filling and grout after hardening. [Effects of the Invention]

[0017] The sensor-equipped ground anchor and grout filling method using it according to the present invention can provide a sensor-equipped ground anchor and grout filling method using it that can easily and accurately grasp the amount of grout to be filled when inserting the sensor-equipped ground anchor into a drilled hole opened in an object to be tensioned (for example, a slope) and filling grout into the filling space between the drilled hole and the sensor-equipped ground anchor (PC steel, which is an example of a tendon) with grout.Furthermore, the sensor-equipped ground anchor and grout filling method using it according to the present invention can provide a sensor-equipped ground anchor and grout filling method using it that can easily check the hardened state of the grout after filling. [Brief explanation of the drawings]

[0018] [Figure 1] 1A is an overall configuration diagram of a test device for a basic performance test of a light intensity sensor provided in a ground anchor with a sensor according to an embodiment of the present invention, and FIG. 1B is an enlarged view of a portion 1B. [Figure 2] FIG. 2 is a diagram for explaining the test results (time change of light intensity when the contact medium is changed) of the basic performance test of FIG. 1. [Figure 3] This figure plots the measurement results, with the horizontal axis representing the light intensity ratio (W) of (light intensity when in contact with water / light intensity when in contact with air) and the vertical axis representing the light intensity ratio (G) of (light intensity when in contact with grout / light intensity when in contact with air). [Figure 4] 1 is a diagram for explaining a grout filling method using a ground anchor with a sensor according to an embodiment of the present invention. FIG. [Figure 5] FIG. 1 is a diagram (first flowchart) for explaining a grout filling method using a ground anchor with a sensor according to an embodiment of the present invention. [Figure 6] FIG. 2 is a diagram (flowchart 2) for explaining a grout filling method using a ground anchor with a sensor according to an embodiment of the present invention. [Figure 7]1 is a diagram for explaining a judgment step in a grout filling method using a ground anchor with a sensor according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] The ground anchor with a sensor according to an embodiment of the present invention and the grout filling method using the same will be described in detail below. In the following description, the ground anchor with a sensor may be simply referred to as the ground anchor. In the drawings referenced below, for ease of understanding, some drawings may depict parts that should be depicted as external shapes rather than internal shapes, as if they were internally seen through; some drawings may depict parts that should be depicted as cross sections rather than external shapes, some drawings may depict parts that should be depicted as external shapes rather than cross sections, some drawings may not be hatched even when they are cross sections, some drawings may be hatched even when they are not cross sections, some drawings may omit detailed structures, and some drawings may not show the same components due to the omission of detailed structures. Furthermore, some drawings may not clearly distinguish between "determination" and "judgment," and some drawings may not clearly distinguish between "detection" and "detection." While tension members used in ground anchors include PC steel, FRP (Fiber Reinforced Plastic), and synthetic fibers, the following description will be given assuming that the tension members used in ground anchors are PC steel.

[0020] <Basic performance test of light intensity sensor> First, with reference to FIGS. 1 to 3, a basic performance test of the light intensity detection sensor 200 provided in the sensor-equipped ground anchor according to the embodiment of the present invention (sensor-equipped ground anchor 300 shown in FIG. 4) will be described.

[0021] This light intensity detection sensor 200 is a sensor that utilizes the fact that light intensity changes depending on the contact medium, and by providing at least one light intensity detection sensor 200 in the sensor-equipped ground anchor 300, the sensor-equipped ground anchor 300 can determine the grout filling state in the grout filling space regardless of the presence or absence of water in the grout filling space. The sensor-equipped ground anchor 300 is a sensor-equipped ground anchor that uses PC steel, and is a component that fills grout between a filling space provided in an object to be tensioned and the PC steel, and tensions and fixes the PC steel after the grout has hardened, thereby reinforcing the object to be tensioned.

[0022] 1(B), the light intensity detection sensor 200 is configured such that the light source is, for example, an LED (light-emitting diode) (the light source can be an incandescent bulb, a mercury lamp, or the like, but the following description will assume the light source is an LED), the light transmission path from the light source is two optical fibers (light-transmitting optical fiber 210 and light-receiving optical fiber 220) bonded in parallel to each other as light-transmitting path 212 and light-receiving path 222, the tips of the optical fibers are cut at a predetermined angle (here, 45°) relative to the optical axis, and the cut surfaces (light-transmitting path-side cut surface 214 and light-receiving path-side cut surface 224) are joined back-to-back at the tip of the sensor to form joint 230 so that they face outward, and the sensor can distinguish between air, water, and grout that come into contact with joint 230 (as contact media). Note that the light intensity detection sensor itself may be a known device.

[0023] Although not shown, a monitoring device (computer) including, for example, a monitoring unit that monitors the received light intensity in real time, a memory unit that stores threshold values, etc., a calculation unit that calculates the light intensity ratio, corrects the threshold value, and determines the contact medium based on the threshold value, and a display unit that displays the monitoring status and the determination result, is connected to the light receiving unit side of this light intensity detection sensor 200, and monitors changes in the light intensity received from the tip of the joint 230 that contacts the contact medium (detection target). Furthermore, in the flowchart described below, the calculation unit makes various determinations based on the changes in light intensity, thereby realizing a grout filling method that simply and accurately determines the grout filling amount and fills the grout filling space with a planned amount of grout. More specifically, the monitoring method involves light emitted from a light source (LED), passing through the light-transmitting optical fiber 210, refracting at the light-transmitting path cut surface 214, exiting the optical fiber, and projecting onto the contact medium (detection target). The light reflected by the contact medium (detection target) is received by the light-receiving path cut surface 224 and transmitted to the light-receiving unit through the light-receiving optical fiber 220. The monitoring unit analyzes the received light and displays the change in light intensity over time on a display unit, as shown in FIG. 2. The intensity of the received light depends on the difference between the refractive index of the medium surrounding the fiber and the refractive index of the optical fiber itself. Note that the closer the refractive index of the optical fiber core is to the refractive index of the contact medium (detection target) in contact with the splice 230, the smaller the amount of light reaching the light-receiving unit. Conversely, the greater the difference between the refractive index of the optical fiber core and the refractive index of the contact medium (detection target) in contact with the splice 230, the greater the amount of light reaching the light-receiving unit. Therefore, by monitoring the light intensity with the light receiving unit, it may be possible to determine whether the contact medium (detection target) in contact with the joint 230 is air, water, or grout, due to the different differences between the refractive index of the optical fiber and the refractive index of air, water, and grout. As will be explained next, this possibility was confirmed by conducting a basic performance test using the test device 100 shown in Figure 1(A).

[0024] Next, a basic performance test was carried out using a test device 100 to confirm that this light intensity detection sensor 200 can be used to determine whether the contact medium (detection target) in contact with the joint 230 is air, water, or grout. As shown in Fig. 1(A), this test device 100 has a transparent hollow cylinder 102 made of, for example, acrylic resin, sealed at the top and bottom with rubber stoppers 104, and is provided with a water and grout injection port 108 below the transparent hollow cylinder 102, the lower cylindrical rubber stopper 104 supports a prestressing steel member 106 that is a substitute for the sensor-equipped ground anchor 300, the light intensity detection sensor 200 is arranged along the prestressing steel member 106, the upper cylindrical rubber stopper 104 supports the prestressing steel member 106 and the light intensity detection sensor 200, and the optical fiber that is the light intensity detection sensor 200 extends to the outside of the transparent hollow cylinder 102. Here, with regard to the transparent hollow cylinder 102, the lower side may be bottomed to begin with or may be bottomed by a rubber stopper 104 (or may have any other form), but the upper rubber stopper 104 has at least a through-hole for extending the light intensity detection sensor 200 to the outside of the transparent hollow cylinder 102 in order to connect it to a monitoring device (computer). Note that if the lower side of the transparent hollow cylinder 102 does not have a bottom, the lower rubber stopper 104 has a support hole (not a through-hole) for the PC steel 106 (to prevent water leakage from the bottom of the transparent hollow cylinder 102). However, in FIG. 1(A), one side (the lower side) of the transparent hollow cylinder 102 has a bottom, so the lower rubber stopper 104 supports the PC steel 106 with a through-hole (just like the upper rubber stopper 104). The joint 230, which is the tip of the light intensity detection sensor 200, is placed at the position indicated by 1B in Figure 1(A), and this is the measurement point for light intensity. The space between the PC steel 106 and the transparent hollow cylinder 102 (corresponding to the drilled hole in the case of slope reinforcement) is the grout filling space 110. Note that, although not limited to these, L(1) = 800 mm and L(2) = 200 mm.

[0025] Using such a test device 100, a test was conducted by injecting water and then grout from the injection port 108, so that the joint 230 of the light intensity detection sensor 200, which is the measurement point, came into contact with air, water, and grout in this order. The results of measuring light intensity using four different light intensity detection sensors 200 are shown in Figures 2(A) to 2(D). Based on these four figures, it was revealed that the tendency for the order of increasing light intensity to be air, grout, and water was common to the four different light intensity sensors.

[0026] For this reason, for example, in the case of a slope reinforcement site where grout filling is actually performed, while grout is being filled into a drilled hole opened in a slope, the following judgment is made with respect to the measurement value (change in the absolute value of light intensity) of the light intensity detection sensor 200. As a calibration process immediately before (or before) the grout filling, the light intensity when water comes into contact with each light intensity detection sensor 200 used at the site is stored as a light intensity threshold (TH). If the light intensity changes during grout filling (if the contact medium changes from air to another object (here, water or grout)), if the light intensity is below this light intensity threshold (TH), it can be determined that water is in contact with the joint 230, which is the tip of the light intensity detection sensor 200. If the light intensity is above this light intensity threshold (TH), it can be determined that grout is in contact with the joint 230, which is the tip of the light intensity detection sensor 200. This is the basic judgment method using light intensity (absolute value) (rather than light intensity ratio).

[0027] Next, a determination method using a light intensity ratio (relative value to air) (rather than light intensity) will be described. Fig. 3 shows a graph based on the measurement results of Fig. 2. Fig. 3 is a graph in which the light intensity is measured for a plurality of (for example, four as shown in Fig. 2) light intensity detection sensors 200 using air, water, and grout as contact media, and the measurement results are plotted on the horizontal axis, where the ratio of the light intensity measured when the contact medium is water to the light intensity measured when the contact medium is air (light intensity ratio (W) = light intensity when in contact with water / light intensity when in contact with air) is taken, and the ratio of the light intensity measured when the contact medium is grout to the light intensity measured when the contact medium is air (light intensity ratio (G) = light intensity when in contact with grout / light intensity when in contact with air) is taken on the vertical axis. As shown in Figure 3, when the measurement results are plotted on the horizontal axis (light intensity ratio (W) = (light intensity when in contact with water / light intensity when in contact with air)) and the vertical axis (light intensity ratio (G) = (light intensity when in contact with grout / light intensity when in contact with air), the regression equation can be expressed as a monotonically increasing line (here, y = 0.9148x + 0.2973). Based on this, the light intensity ratio (W) when one light intensity detection sensor is attached to water is used as a threshold value. If it is below the threshold, the contact medium is determined to be water, and if it is above the threshold, the contact medium is determined to be grout. This is because, as shown in Figure 3, the light intensity ratio (W) = (light intensity when in contact with water / light intensity when in contact with air) is always less than the light intensity ratio (G) = (light intensity when in contact with grout / light intensity when in contact with air). This is the basic discrimination method using the light intensity ratio (relative to air) (rather than light intensity).

[0028] For this reason, for example, in the case of a slope reinforcement site where grout filling is actually performed, while grout is being filled into a drilled hole opened in a slope, a judgment is made as follows with respect to a change in the light intensity ratio based on the measurement value of the light intensity detection sensor 200. As a calibration process immediately before (or before), the light intensity ratio (W) (=light intensity when in contact with water / light intensity when in contact with air) based on the respective light intensities when each light intensity detection sensor 200 used at the site is brought into contact with air and water is stored as a light intensity ratio threshold value (TH) (together with the light intensity when the contact medium is air). If the light intensity changes during grout filling, and the light intensity ratio calculated by dividing the changed light intensity (the contact medium is assumed to be other than air) by the light intensity measured in the calibration process when the contact medium is air) is less than or equal to the light intensity ratio threshold (TH), it can be determined that water is in contact with the joint 230, which is the tip of the light intensity detection sensor 200. If the light intensity ratio is greater than the light intensity ratio threshold (TH), it can be determined that grout is in contact with the joint 230, which is the tip of the light intensity detection sensor 200. This is the basic method of determination using the light intensity ratio (relative value to air) (rather than light intensity). This determination method using the light intensity ratio is particularly effective when the light intensity changes during grout filling and the contact medium changes from air to another object (here, water or grout) and it determines whether the contact medium has changed from air to water or from air to grout.

[0029] Whether the discrimination method uses light intensity or the discrimination method uses a light intensity ratio, it is also preferable to correct the threshold value (based on the weather, temperature, humidity, water temperature, etc. at the site) to set a corrected threshold value, and to determine that the contact medium is water when the value is below the corrected threshold value, and that the contact medium is grout when the value is above the corrected threshold value. Furthermore, it is also preferable to provide a numerical range for the threshold value for accurate discrimination.

[0030] <Grout filling method> The grout filling method according to this embodiment, which was established through the above-mentioned <Basic performance test of the light intensity sensor>, will be described below. The discrimination method using light intensity and the discrimination method using the light intensity ratio have the following insertion step and filling step in common. Insertion step: The position of the joint 230 of the light intensity detection sensor 200 is determined so as to correspond to the position where grout and / or water is to be detected (more specifically, without being limited to, for example, the position of (sensor (1)) and the position of (sensor (2)) shown in FIG. 4 together with the symbol of the joint 230 which is the tip of the light intensity detection sensor 200), and the sensor-equipped ground anchor 300 is inserted into the drilled hole 400 together with at least one (here, two) light intensity detection sensor. Filling step: Filling grout between the filling space 310 and the PC steel. When a discrimination method using light intensity is used, in the filling step, grout and / or water are detected at the desired position based on the change in light intensity detected by the light intensity detection sensor 200 (when the contact medium is changed from air), and grout is filled up to a predetermined position (planned amount). When the discrimination method using the light intensity ratio is used, in the filling step, grout and / or water are detected at the desired detection position based on the change in the light intensity ratio (when the contact medium is from air) calculated based on the light intensity detected by the light intensity detection sensor 200, and grout is filled up to a predetermined position (planned amount).

[0031] Figure 4 shows a schematic diagram of a construction site for slope reinforcement work using this grout filling method. At this construction site, the above-mentioned grout filling method is carried out, in which a sensor-equipped ground anchor 300 is inserted into a drilled hole 400 opened in the slope, and grout is filled into the filling space 310 between the drilled hole 400 and the sensor-equipped ground anchor 300 (prestressing steel). Joints 230, which are the tips of the light intensity detection sensors 200, are provided at two locations (one or more) shown as sensors (1) and (2). In addition, a grout hole 302 is provided near the tip of the sensor-equipped ground anchor 300 to pressurize and inject grout into the filling space 310. Note that a sheath pipe 304 contains at least an optical fiber (light intensity detection sensor 200), prestressing steel (typically a prestressing steel strand), and a grout supply pipe.

[0032] Here, it is also preferable that the light intensity detection sensor 200 is integrated with the ground anchor 300 with the sensor, as this makes it easier to handle the ground anchor 300 with the sensor.

[0033] <Grout filling method: Flowchart> The grout filling method described above will be described in detail with reference to the flowcharts shown in Figures 5 and 6. In the following flowcharts and in Figures 5 and 6, the light intensity sensor may be referred to simply as the sensor, and the sensor-equipped ground anchor may be referred to simply as the anchor. In the following, the terms grout injection, pressurized grout injection, and grout filling are used interchangeably. In the following, the determination step will be described using both a determination method using light intensity (absolute value) and a determination method using a light intensity ratio (relative value to air) (rather than light intensity). However, determination may be performed using only one of the determination methods. The flowcharts do not include a grout injection stop process after the start of the grout injection process, and instead include the grout injection process again. This is likely due to the assumption that the grout injection may be temporarily stopped during various determinations using the light intensity detection sensor 200 to ensure stable measurement of the light intensity by the light intensity detection sensor 200.

[0034] In step (hereinafter sometimes referred to as S) 100, a monitoring device is used to input light to the sensors, detect the light intensity, and calculate and store the light intensity ratio. This means that, as a calibration immediately before (or before) grout filling, the monitoring device is used to measure the light intensity when water is brought into contact with each (individual) light intensity detection sensor 200 used on-site. The light intensity is then stored in a memory unit as a light intensity threshold (TH) used in the light intensity determination method. The light intensity ratio (W) calculated by the calculation unit as the "light intensity when water is brought into contact / light intensity when air is brought into contact" when air and water are brought into contact is then stored in the memory unit as a light intensity ratio threshold (TH) used in the light intensity ratio determination method (together with the light intensity measured in the calibration process when the contact medium is air). These are used as thresholds in the judgment step. For convenience of explanation, the light intensity threshold (TH) and light intensity ratio threshold (TH) of the light intensity detection sensors 200 installed at two (one or more) locations, sensor (1) and sensor (2), are assumed to be the same value. In reality, since it is expected that the characteristics of each individual sensor will differ, the memory unit will store as many light intensity thresholds (TH) and / or light intensity ratio thresholds (TH) as there are sensors. Also, if the light intensity changes during grout filling, the light intensity ratio is calculated based on the light intensity after the change (the contact medium is assumed to be other than air) / the light intensity measured in the calibration process when the contact medium is air), and the magnitude relationship with the light intensity ratio threshold (TH) is compared to determine the contact medium (this will not be explained repeatedly in each judgment step shown below).

[0035] In S102, the sensor-equipped ground anchor 300 is inserted into the drilled hole 400 manually or by machine (peripheral device). In S104, the monitoring device determines whether the light intensity of sensors (1) and (2) changes immediately after insertion. More specifically, it determines whether the light intensity or light intensity ratio of sensors (1) and (2) is equal to or less than a threshold value (light intensity threshold (TH) or light intensity ratio threshold (TH)) (whether the contact medium of the junction 230 of the light intensity detection sensor 200, which is sensor (1) and sensor (2), has changed from air to water). If it is determined that the light intensity of sensors (1) and (2) changed immediately after insertion (YES in S104), the process proceeds to S106. If not (NO in S104), the process proceeds to S200.

[0036] In S106, the monitoring device determines that groundwater is present up to the position of sensor (2) (groundwater has reached the position of sensor (2), which is the sensor at the entrance side of the drilling hole 400 out of the two sensors). Then, the process proceeds to S108.

[0037] In S108, grout is injected (pressurized injection) into the filling space 310 using the sensor-equipped ground anchor 300 (and its peripheral devices). In S110, the monitoring device determines whether the light intensity of the sensor (1) changes during grout filling. More specifically, it determines whether the light intensity or light intensity ratio of the sensor (1) is greater than a threshold value (light intensity threshold (TH) or light intensity ratio threshold (TH)) (whether the contact medium of the joint 230 of the light intensity detection sensor 200, which is the sensor (1), has changed from water to grout). If it is determined that the light intensity of the sensor (1) has changed during grout filling (YES in S110), the process proceeds to S112. If not (NO in S110), the process returns to S108, and grout filling continues.

[0038] In S112, the monitoring device determines that the grout has reached the position of sensor (1) (grout has filled up to the position of sensor (1), which is the farthest of the two sensors in the drilled hole 400). Then, the process proceeds to S114.

[0039] In S114, grout is injected (pressurized injection) into the filling space 310 using the sensor-equipped ground anchor 300 (and its peripheral devices). In S116, the monitoring device determines whether the light intensity of sensor (2) changes during grout filling. More specifically, it determines whether the light intensity or light intensity ratio of sensor (2) is greater than a threshold value (light intensity threshold (TH) or light intensity ratio threshold (TH)) (whether the contact medium of the joint 230 of the light intensity detection sensor 200, which is sensor (2), has changed from water to grout). If it is determined that the light intensity of sensor (2) has changed during grout filling (YES in S116), the grout filling process is completed. If not (NO in S116), the process returns to S114, and grout filling continues.

[0040] In S200, the monitoring device determines whether the light intensity of sensor 1 changes immediately after insertion. More specifically, it determines whether the light intensity or light intensity ratio of sensor 1 is equal to or less than a threshold (light intensity threshold (TH) or light intensity ratio threshold (TH)) (whether the contact medium of joint 230 of light intensity detection sensor 200, which is sensor 1, has changed from air to water). If it is determined that the light intensity of sensor 1 changed immediately after insertion (YES in S200), the process proceeds to S206. If not (NO in S200), the process proceeds to S300.

[0041] In S206, the monitoring device determines that groundwater is present up to the position of sensor (1) (groundwater has reached the position of sensor (1), which is the farthest of the two sensors in the drilled hole 400). Then, the process proceeds to S208.

[0042] In S208, grout is injected (pressurized injection) into the filling space 310 using the sensor-equipped ground anchor 300 (and its peripheral devices). In S210, the monitoring device determines whether the light intensity of the sensor (1) changes during grout filling. More specifically, it determines whether the light intensity or light intensity ratio of the sensor (1) is greater than a threshold value (light intensity threshold (TH) or light intensity ratio threshold (TH)) (whether the contact medium of the joint 230 of the light intensity detection sensor 200, which is the sensor (1), has changed from water to grout). If it is determined that the light intensity of the sensor (1) has changed during grout filling (YES in S210), the process proceeds to S212. If not (NO in S210), the process returns to S208, and grout filling continues.

[0043] In S212, the monitoring device determines that the grout has reached the position of sensor (1) (grout has filled up to the position of sensor (1), which is the innermost of the two sensors in the drilled hole 400). Then, the process proceeds to S214.

[0044] In S214, grout is injected (pressurized injection) into the filling space 310 using the sensor-equipped ground anchor 300 (and its peripheral devices). In S216, the monitoring device determines whether the light intensity of sensor (2) changes during grout filling. More specifically, it determines whether the light intensity or light intensity ratio of sensor (2) is equal to or less than a threshold value (light intensity threshold (TH) or light intensity ratio threshold (TH)) (whether the contact medium of the joint 230 of the light intensity detection sensor 200, which is sensor (2), has changed from air to water). If it is determined that the light intensity of sensor (2) has changed during grout filling (YES in S216), the process proceeds to S218. If not (NO in S216), the process returns to S214, and grout filling continues.

[0045] In S218, the monitoring device determines that groundwater has reached the position of sensor (2) (groundwater has been pushed up by the grout and has risen to the position of sensor (2), one of the two sensors, which is located on the entrance side of drilling 400). Then, the process proceeds to S220.

[0046] In S220, grout is injected (pressurized injection) into the filling space 310 using the sensor-equipped ground anchor 300 (and its peripheral devices). In S222, the monitoring device determines whether the light intensity of sensor (2) changes further during grout filling. More specifically, it determines whether the light intensity or light intensity ratio of sensor (2) is greater than a threshold value (light intensity threshold (TH) or light intensity ratio threshold (TH)) (whether the contact medium of the joint 230 of the light intensity detection sensor 200, which is sensor (2), has changed from water to grout). If it is determined that the light intensity of sensor (2) has changed during grout filling (YES in S222), the grout filling process is completed. If not (NO in S222), the process returns to S220, and grout filling continues.

[0047] In S300, grout is injected (pressurized injection) into the filling space 310 using the sensor-equipped ground anchor 300 (and its peripheral devices). In S302, the monitoring device determines whether a change in the light intensity of the sensor (1) during grout filling is a change due to contact with water. More specifically, it determines whether the light intensity or light intensity ratio of the sensor (1) is equal to or less than a threshold value (light intensity threshold (TH) or light intensity ratio threshold (TH)) (whether the contact medium of the joint 230 of the light intensity detection sensor 200, which is the sensor (1), has changed from air to water). If it is determined that the change in the light intensity of the sensor (1) during grout filling is a change due to contact with water (YES in S302), the process proceeds to S304. If not (NO in S302), the process proceeds to S400. If the result of S302 is NO (if the light intensity or light intensity ratio of the sensor (1) is greater than the threshold value (light intensity threshold value (TH) or light intensity ratio threshold value (TH))), it means that the contact medium of the joint 230 of the light intensity detection sensor 200, which is the sensor (1), has changed from air to grout.

[0048] The determination in S302 differs from other determination (judgment) steps in that it selectively determines whether air is replaced by water or air is replaced by grout, which can make the determination more difficult than other determination (judgment) steps, and therefore a determination using a light intensity ratio may be preferable to a determination using light intensity. For example, the state before the determination process in S302 is either that groundwater is accumulating at a position further back than the back sensor (1) of the drilled hole 400 (YES determination will be made in S302) (NO determination will be made in S200, which is a process before the processing of S302, and no water is present at the back sensor (1) immediately after the sensor-equipped ground anchor 300 is inserted into the drilled hole 400 (before grout is filled in)), or that there is no groundwater present in the drilled hole 400 at all (NO determination will be made in S302). Even if groundwater is accumulating further back than the sensor (1) at the back of the drilling hole 400, if the amount of water is small, the small amount of water will rise along with the grout, making it difficult to make a judgment in S302. Note that, since the specific gravity of grout, when water is used as the standard substance, exceeds 1 (grout density (mass per unit volume) > water density (mass per unit volume)), in the filling space, the grout will be located at the bottom and the water at the top. If the amount of groundwater is large (although this depends on the grout filling speed), this positional relationship will be clearly distinguishable, but if the amount of groundwater is small, it is expected that this positional relationship will be difficult to clearly distinguish.

[0049] In S304, the monitoring device determines that groundwater has reached the position of sensor (1) (groundwater has been pushed up by the grout and has risen to the position of sensor (1), which is the sensor at the back of the drilled hole 400, out of the two sensors). Then, the process proceeds to S306.

[0050] In S306, grout is injected (pressurized injection) into the filling space 310 using the sensor-equipped ground anchor 300 (and its peripheral devices). In S308, the monitoring device determines whether the light intensity of the sensor (1) changes during grout filling. More specifically, it determines whether the light intensity or light intensity ratio of the sensor (1) is greater than a threshold value (light intensity threshold (TH) or light intensity ratio threshold (TH)) (whether the contact medium of the joint 230 of the light intensity detection sensor 200, which is the sensor (1), has changed from water to grout). If it is determined that the light intensity of the sensor (1) has changed during grout filling (YES in S308), the process proceeds to S310. If not (NO in S308), the process returns to S306, and grout filling continues.

[0051] In S310, the monitoring device determines that the grout has reached the position of sensor (1) (grout has filled up to the position of sensor (1), which is the farthest of the two sensors in the drilled hole 400). Then, the process proceeds to S312.

[0052] In S312, grout is injected (pressurized injection) into the filling space 310 using the sensor-equipped ground anchor 300 (and its peripheral devices). In S314, the monitoring device determines whether the light intensity of sensor (2) changes during grout filling. More specifically, it determines whether the light intensity or light intensity ratio of sensor (2) is equal to or less than a threshold value (light intensity threshold (TH) or light intensity ratio threshold (TH)) (whether the contact medium of the joint 230 of the light intensity detection sensor 200, which is sensor (2), has changed from air to water). If it is determined that the light intensity of sensor (2) has changed during grout filling (YES in S314), the process proceeds to S316. If not (NO in S314), the process returns to S312, and grout filling continues.

[0053] In S316, the monitoring device determines that groundwater has reached the position of sensor (2) (groundwater has been pushed up by the grout and has risen to the position of sensor (2), one of the two sensors, which is located on the entrance side of drilling 400). Then, the process proceeds to S318.

[0054] In S318, grout is injected (pressurized injection) into the filling space 310 using the sensor-equipped ground anchor 300 (and its peripheral devices). In S320, the monitoring device determines whether the light intensity of sensor (2) changes further during grout filling. More specifically, it determines whether the light intensity or light intensity ratio of sensor (2) is greater than a threshold value (light intensity threshold (TH) or light intensity ratio threshold (TH)) (whether the contact medium of the joint 230 of the light intensity detection sensor 200, which is sensor (2), has changed from water to grout). If it is determined that the light intensity of sensor (2) has changed during grout filling (YES in S320), the grout filling process is completed. If not (NO in S320), the process returns to S318, and grout filling continues.

[0055] In S400, the monitoring device determines that the grout has reached the position of sensor (1) (there is no groundwater in the drilled hole 400, and the grout has risen up to the position of sensor (1), which is the farthest of the two sensors in the drilled hole 400). Then, the process proceeds to S402.

[0056] In S402, grout is injected (pressurized injection) into the filling space 310 using the sensor-equipped ground anchor 300 (and its peripheral devices). In S404, the monitoring device determines whether the light intensity of the sensor (2) changes during grout filling. More specifically, it determines whether the light intensity or light intensity ratio of the sensor (2) is greater than a threshold value (light intensity threshold value (TH) or light intensity ratio threshold value (TH)) (whether the contact medium of the joint 230 of the light intensity detection sensor 200, which is the sensor (2), has changed from air to grout). If it is determined that the light intensity of the sensor (2) has changed during grout filling (YES in S404), the grout filling process is completed. If not (NO in S404), the process returns to S402, and grout filling continues.

[0057] The grout filling method according to this embodiment can be realized by executing the flowcharts described with reference to FIGS. 5 and 6 (by a monitoring device, manually, or machine (peripheral device)).

[0058] As described above, with the sensor-equipped ground anchor of this embodiment and the grout filling method using it, when the sensor-equipped ground anchor is inserted into a drilled hole opened in an object to be tensioned (for example, a slope), and the filling space between the drilled hole and the sensor-equipped ground anchor (PC steel) is filled with grout, the amount of grout filled can be easily and accurately determined.

[0059] <Modification> A modification of this embodiment will be described below with reference to FIG.

[0060] Figure 7 is a diagram showing the light intensity of air, water, grout at the time of filling, and grout after hardening, and it is clear from Figure 7 that the light intensity changes between the grout at the time of filling and the grout after hardening. Using this, the light intensity detection sensor 200 provided in the sensor-equipped ground anchor according to this embodiment is configured to be able to distinguish between air, water, and grout, as well as to distinguish between grout at the time of filling and grout after hardening.

[0061] The grout filling method using the sensor-equipped ground anchor according to this embodiment further includes, after the above-described filling step, a determination step of determining that the grout filled in the filling space has hardened based on a change in the light intensity detected by the light intensity detection sensor 200.

[0062] As described above, the sensor-equipped ground anchor and grout filling method using the same according to this modified example can provide a sensor-equipped ground anchor and grout filling method using the same that can easily check the hardened state of grout after filling.

[0063] It should be noted that the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Industrial Applicability]

[0064] The present invention is preferred for a sensor-equipped ground anchor and a grout filling method using the same when inserting the sensor-equipped ground anchor into a drilled hole opened in an object to be tensioned (for example, a slope) and filling the filling space between the drilled hole and the sensor-equipped ground anchor (a prestressing steel member as an example of a tendon) with grout, and is particularly preferred in that it allows the amount of grout filled to be grasped easily and accurately.Furthermore, the present invention is particularly preferred in that it allows the hardened state of the grout after filling to be easily confirmed. [Explanation of symbols]

[0065] 100 Test Equipment 200 Light intensity detection sensor (sensor) 300 Ground anchor with sensor (ground anchor, anchor) 400 Drilling

Claims

1. A ground anchor with a sensor that fills grout between a filling space provided in an object to be tensioned and a tendon, and tensions and fixes the tendon after the grout hardens to reinforce the object to be tensioned, A ground anchor with a sensor, characterized in that it is equipped with at least one light intensity detection sensor that utilizes the fact that light intensity changes depending on the contact medium, and is therefore capable of determining the grout filling state in the filling space regardless of whether water is present in the filling space.

2. 2. The ground anchor with a sensor according to claim 1, wherein the light intensity detection sensor is capable of distinguishing between air, water, and grout.

3. 3. The ground anchor with a sensor according to claim 2, wherein the light intensity detection sensor can distinguish between air, water, and grout, as well as between grout at the time of filling and grout after hardening.

4. 3. The ground anchor with sensor according to claim 2, wherein the light intensity detection sensor is integrated with the ground anchor with sensor.

5. For the plurality of light intensity detection sensors, light intensity is measured using air, water, and grout as the contact medium; The ratio of the light intensity measured when the contact medium was water to the light intensity measured when the contact medium was air (light intensity ratio (W) = light intensity when in contact with water / light intensity when in contact with air) is plotted on the horizontal axis. The ratio of the light intensity measured when the contact medium is grout to the light intensity measured when the contact medium is air (light intensity ratio (G) = light intensity when in contact with grout / light intensity when in contact with air) is plotted on the vertical axis.

3. The ground anchor with sensor according to claim 2, characterized in that, based on the fact that a regression equation when measurement results are plotted can be expressed as a monotonically ascending straight line, the light intensity ratio (W) when one of the light intensity detection sensors is attached to water is set as a threshold value, and if the light intensity ratio is equal to or less than the threshold value, the contact medium is determined to be water, and if the light intensity ratio is greater than the threshold value, the contact medium is determined to be grout.

6. 6. The ground anchor with sensor according to claim 5, wherein the threshold value is corrected to set a corrected threshold value, and when the threshold value is equal to or less than the corrected threshold value, the contact medium is determined to be water, and when the threshold value is greater than the corrected threshold value, the contact medium is determined to be grout.

7. A grout filling method using the sensor-equipped ground anchor according to claim 2, an insertion step of determining a position of the light intensity detection sensor corresponding to a position where grout and / or water is to be detected, and inserting the sensor-equipped ground anchor together with at least one light intensity detection sensor into a drilled hole; a filling step of filling grout between the filling space and the tendon, A grout filling method characterized in that in the filling step, grout is filled to a predetermined position while detecting grout and / or water at the position based on a change in light intensity detected by the light intensity detection sensor.

8. A grout filling method using the sensor-equipped ground anchor according to claim 5, an insertion step of determining a position of the light intensity detection sensor corresponding to a position where grout and / or water is to be detected, and inserting the sensor-equipped ground anchor together with at least one light intensity detection sensor into a drilled hole; a filling step of filling grout between the filling space and the tendon, A grout filling method characterized in that in the filling step, grout is filled to a predetermined position while detecting grout and / or water at the position based on a change in the light intensity ratio based on the light intensity detected by the light intensity detection sensor.

9. Using the light intensity detection sensor that can distinguish between air, water, and grout, as well as between grout at the time of filling and grout after hardening, 9. The grout filling method according to claim 7, further comprising a determination step of determining, after the filling step, that the grout filled in the filling space has hardened based on a change in the light intensity detected by the light intensity detection sensor.

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