JP6926743B2 - How to check concrete filling - Google Patents

Description

The present invention relates to a method for confirming the filling of concrete in order to grasp the filling status of the cast concrete when the concrete is cast into the underground hole to construct a cast-in-place concrete underground structure.

Conventionally, when constructing an underground structure such as a cast-in-place concrete pile in the ground, the shape of the hole wall of the underground hole provided by excavating the ground is the outer shape of the underground structure to be constructed. It is confirmed by using various measuring means that they match. As a result, after considering that the finished shape of the underground structure to be constructed satisfies the management standard, concrete is placed in the underground hole thereafter to construct the underground structure.

However, it is assumed that the hole wall of the underground hole may collapse during the concrete placing work, or the concrete filling failure may occur. Therefore, even if the hole wall shape before the concrete placing work is managed. , The finished shape of the underground structure after construction does not always meet the standard.

Therefore, for example, in Patent Document 1, a hole is provided near the center of a concrete pile constructed in the ground, and an electromagnetic wave or ultrasonic wave transmitter and receiver are installed in the hole, and electromagnetic waves or electromagnetic waves are provided in the radial direction of the pile. A method of starting ultrasonic waves and grasping the outer shape of a concrete pile from the reflected waves is disclosed. This method can be adopted when confirming the finished shape of a hardened concrete pile after construction or when grasping the finished shape of an existing pile buried in the ground. However, it is not possible to estimate the finished shape of the concrete pile to be constructed from the filling status of uncured concrete during construction.

Under such circumstances, as a method of confirming the filling state of concrete placed in the formwork before hardening, for example, Patent Document 2 discloses a concrete construction management method using an optical fiber. Specifically, an optical fiber capable of detecting the temperature is installed in a portion of the formwork where poor concrete filling is likely to occur. Then, while placing concrete in the formwork, the detected temperature of the optical fiber is monitored, and when the detected temperature shows a value different from the air temperature, it is determined that the part where the optical fiber is installed is filled with concrete. ..

Japanese Unexamined Patent Publication No. 2003-337015 Japanese Unexamined Patent Publication No. 2002-327535

Since the method of Patent Document 2 is a method of confirming the filling state of concrete by comparing the air temperature with the detected temperature detected by the optical fiber, it can be adopted when constructing a concrete skeleton in an aerial environment, and also. This method is suitable when the position where the concrete filling defect is likely to occur is specified in advance.

However, in the mode of placing underwater concrete in the stabilizer, such as when constructing a concrete underground structure in an underground hole filled with a stabilizer, the method of confirming the concrete filling status is Not revealed. In addition, a method of estimating the position where the concrete filling defect occurs when the part where the concrete filling defect may occur cannot be specified has not been clarified.

The present invention has been made in view of such a problem, and its main purpose is to accurately grasp the filling state of concrete placed in an underground hole filled with a stabilizer before the concrete hardens. It is to provide a possible method for confirming the filling of concrete.

In order to achieve such an object, in the method for confirming the filling of concrete of the present invention, a plurality of optical fiber sensors are placed in an underground hole filled with a stabilizer while ensuring a predetermined distance from the hole wall in the circumferential direction of the hole wall. the rewritable installed spaced in a first step of setting the temperature of the stabilizing liquid in contact with the optical fiber sensor to an initial temperature, after Da設concrete, the concrete for the time of setting the initial temperature A second step of detecting the amount of expansion and contraction of the optical fiber sensor after casting and measuring the temperature change from the initial temperature based on the amount of expansion and contraction at at least one place or more on the optical fiber sensor. At the measurement position of the optical fiber sensor in which the temperature rise is confirmed based on the temperature change, it is determined that the concrete has come into contact with the optical fiber sensor, and the underground hole is formed based on the determined measurement position. It is characterized by comprising a third step of estimating the finished shape of the underground structure to be constructed.

According to the concrete filling confirmation method of the present invention described above, the amount of expansion and contraction of the optical fiber sensor after concrete placement is measured with reference to the optical fiber sensor in contact with the stabilizer, and the temperature change is measured. Therefore, it is possible to accurately grasp how the contact material in contact with the optical fiber sensor in the underground hole is replaced with concrete having a temperature different from that of the stabilizer, and to confirm the filling status of the concrete.

If the optical fiber sensor has a measurement position where contact with concrete is not confirmed, the underground hole is based on the measurement position on the optical fiber sensor and the installation position of the optical fiber sensor in the underground hole. It is possible to identify the position where the concrete filling failure occurs in. This makes it possible to take measures suitable for the situation, such as adding concrete or using a concrete vibrator, depending on the position and scale of the poor filling, and it is not possible to visually check the filling status of concrete. Even so, it is possible to construct a high-quality concrete underground structure.

Further, the finished shape of the underground structure to be constructed is estimated based on the measurement position determined to be in contact with the concrete in each of the plurality of optical fiber sensors installed in the underground hole. As a result, it is possible to evaluate whether or not the estimated finished shape meets the management standard at the stage where the concrete placed in the underground hole is uncured. Therefore, even if it is determined that the control standard is not satisfied, it is possible to implement countermeasures to satisfy the standard at an early stage. Further, when re-construction is required, complicated labor such as removing the underground structure after hardening becomes unnecessary, and the work process can be significantly shortened.

In the concrete filling confirmation method of the present invention, in the first step, the optical fiber sensor is attached to the reinforcing bar cage to be built in the underground hole while securing a predetermined distance from the reinforcing bar cage via a connecting member. It is characterized by arranging.

According to the concrete filling confirmation method of the present invention described above, since the optical fiber sensor is supported by the reinforcing bar cage, the optical fiber sensor is installed even if the lateral pressure generated when the concrete is placed or the water pressure of the stabilizer acts. The position can be held at a fixed position, and the position or range in which the concrete filling status is determined can be accurately specified.

According to the present invention, utilizing the fact that concrete and the stabilizing liquid have different temperatures, the amount of expansion and contraction of the optical fiber sensor after concrete placement is measured with reference to the optical fiber sensor in contact with the stabilizing liquid. However, by measuring the temperature change, it is possible to accurately grasp the filling status of the concrete placed in the underground hole filled with the stabilizer before the concrete hardens.

It is a figure which shows the optical fiber sensing system in embodiment of this invention. It is a figure which shows the filling confirmation apparatus in embodiment of this invention. It is a figure which shows the state which installed the optical fiber sensor in embodiment of this invention. It is a figure which shows the procedure of the concrete filling confirmation method in embodiment of this invention. It is a figure which shows the state of the verification experiment of the concrete filling confirmation method in embodiment of this invention. It is a figure which shows the verification result in the verification experiment of the concrete filling confirmation method in embodiment of this invention.

In the present invention, in order to construct a concrete underground structure, when placing concrete in an underground hole filled with a stabilizer, a concrete filling state that cannot be visually confirmed can be checked by using an optical fiber sensor. This is a method of confirming and estimating the finished shape of the underground structure to be constructed from the filling status of the concrete before hardening.

In the present embodiment, a case where a cast-in-place pile made of reinforced concrete is constructed as an underground structure is taken as an example, and a concrete filling confirmation method will be described with reference to FIGS. 1 to 6. The underground structure is not limited to cast-in-place piles, and may be an underground continuous wall, a water blocking wall, or the like, and the underground structure may be an SC structure or a concrete structure. ..

Prior to explaining the concrete filling confirmation method, first, the outline of the optical fiber sensing system mounted on the filling confirmation device used in the concrete filling confirmation method will be described.

As shown in FIG. 1A, the optical fiber sensing system 7 is a system for calculating the temperature change of the contact object 9 in contact with the optical fiber sensor 71, and is attached to the optical fiber sensor 71 and one end of the optical fiber sensor 71. It includes a measuring device 72 to be connected and an output device 73 that displays an output result output by the measuring device 72.

The optical fiber sensor 71 is a material that expands and contracts in response to a temperature change of the contact object 9, and as shown in FIG. 1 (b), has a thermal conductivity so that heat is conducted while external pressure does not act. It is covered with a protective tube 74 made of high stainless steel, and is brought into contact with the contact object 9 through the protective tube 74.

The measuring device 72 oscillates a pulse laser and causes it to enter the optical fiber sensor 71, and at the same time, the optical fiber sensor 71 undergoes expansion and contraction change from minute reflected light (for example, Rayleigh scattered light) generated in the optical fiber sensor 71. The amount of change when it occurs (hereinafter referred to as the amount of expansion and contraction) is measured. Further, based on this expansion / contraction amount, the temperature change of the contact object 9 before and after the expansion / contraction change occurs in the optical fiber sensor 71 is calculated.

The output device 73 is a device that displays the output result of the measuring device 72, and in the present embodiment, a personal computer is adopted. The output device 73 may be any device such as a printing device such as a printer or a display device such as a monitor as long as it can display the output result of the measuring device 72 so that it can be visually confirmed.

As a method of calculating the temperature change of the contact object 9 using the optical fiber sensing system 7 having such a configuration, first, the temperature of the contact object 9 (hereinafter, hereinafter, in the state where the optical fiber sensor 71 is in contact with the contact object 9). The initial temperature) is measured. Alternatively, the temperature of the contact object 9 is measured in advance before the optical fiber sensor 71 is brought into contact with the optical fiber sensor 71.

Next, the pulse laser was incident on the optical fiber sensor 71 from the measuring device 72, and the minute reflected light generated in the optical fiber sensor 71 was constantly detected by the measuring device 72, causing the optical fiber sensor 71 to expand and contract. Measure the amount of expansion and contraction. Based on this amount of expansion and contraction, the temperature difference between the contact object 9 and the initial temperature immediately after the change in expansion and contraction of the optical fiber sensor 71 occurs (hereinafter referred to as temperature change) is calculated.

The optical fiber sensor 71 can continuously calculate the temperature change of the contact object 9 along the optical fiber sensor 71 with a position resolution of millimeter level. Therefore, when the contact object 9 is a long object, as shown in FIG. 1A, the optical fiber sensor 71 is extended along the length direction of the contact object 9 to bring them into contact with each other. Therefore, the temperature change of the contact object 9 can be calculated over the entire length.

As described above, according to the optical fiber sensing system 7, when the contact material 9 in contact with the optical fiber sensor 71 is always the same substance, the output device 73 shows how the temperature of the contact material 9 changes with time. Can be monitored via. On the other hand, when the contact object 9 in contact with the optical fiber sensor 71 is replaced with the passage of time, if the contact objects 9 before and after the replacement have different temperatures, the optical fiber sensor 71 is replaced with the passage of time. It can be confirmed that the contact object 9 that comes into contact with the light fiber has been replaced.

Therefore, in the present embodiment, when constructing a cast-in-place pile made of reinforced concrete, as shown in FIG. 4 (a), the stabilizer 2 that fills the underground hole 1 after drilling and FIG. 4 (b) are used. As shown, in view of the fact that the temperature is different from that of the concrete 3 that replaces the stabilizer 2 in the underground hole 1, the filling confirmation device 6 as shown in FIG. 2 is equipped with the optical fiber sensing system 7 and the filling confirmation device 6 is installed. It was decided to confirm the filling status of the concrete 3 in the underground hole 1 by grasping how the underground hole 2 filled with the stabilizer 2 is replaced with the concrete 3.

As shown in FIG. 2, the filling confirmation device 6 has a plurality of optical fiber sensors 71 provided in the optical fiber sensing system 7, and also includes a connector box 8 for connecting the plurality of optical fiber sensors 71 and the measuring device 72. It has.

Further, each of the plurality of optical fiber sensors 71 extends in the depth direction of the underground hole 1, the upper end is located above the underground hole 1, and the lower end is located near the bottom of the underground hole 1. As shown in FIG. 3, the holes are arranged at regular intervals in the circumferential direction of the hole wall 11 while ensuring a certain distance from the hole wall 11 of the underground hole 1. In the present embodiment, the optical fiber sensor 71 is installed in advance on the ground work for the reinforcing bar cage 4 before being built in the underground hole 1.

Specifically, a synthetic resin connecting member is provided on the outer peripheral surface of the reinforcing bar cage 4 facing the hole wall 11 so that the optical fiber sensor 71 is arranged at a certain distance from both the reinforcing bar cage 4 and the hole wall 11. It is installed via 5. As a result, when the reinforcing bar cage 4 is built in the underground hole 1, a three-dimensional shape similar to the hole wall 11 formed by the plurality of optical fiber sensors 71 is formed in the ground inside the underground hole 1. It is formed at a position coaxial with the hole 1 and close to the hole wall 11.

Since the optical fiber sensor 71 does not come into contact with either the reinforcing bar cage 4 or the hole wall 11, it is not affected by geothermal heat and can be prevented from being affected by heat conduction from the reinforcing bar cage 4. .. Further, since it is supported by the reinforcing bar cage 4 via the connecting member 5, the optical fiber sensor 71 for the underground hole 2 is affected by the lateral pressure when the concrete 3 is placed or the water pressure of the stabilizing liquid 2. Can be held in place.

As shown in FIG. 2, the plurality of optical fiber sensors 71 connect the upper ends to the measuring device 72 via the connector box 8. Then, the pulse laser oscillated from the measuring device 72 is incident on each of the plurality of optical fiber sensors 71 via the connector box 8. Further, the minute reflected light generated inside each of the plurality of optical fiber sensors 71 is collected via the connector box 8 and transmitted to the measuring device 72.

The concrete filling confirmation method to be carried out when constructing a cast-in-place pile made of reinforced concrete using the filling confirmation device 6 described above is shown below.

<First step>
First, in the first step, as shown in FIG. 4A, the reinforcing bar cage 4 in which the optical fiber sensor 71 is attached is built in the underground hole 1 filled with the stabilizer 2. As a result, the optical fiber sensor 71 is arranged in a state where it is not affected by the temperature from each of the ground and the reinforcing bar cage 4 by maintaining a predetermined distance from the hole wall 11 and the reinforcing bar cage 4, and the optical fiber 71 is arranged. The whole is in contact with the stabilizer 2.

Next, as shown in FIG. 2, the upper ends of each of the plurality of optical fiber sensors 71 are connected to the connector box 8 and connected to the measuring device 72 via the connector box 8. At the same time as or before and after these operations, the temperature of the stabilizer 2, that is, the initial temperature is grasped.

<Second step>
Next, as shown in FIG. 4B, the stabilizer 2 is discharged while the concrete 3 is cast using the tremie tube 10 while the pulse laser is incident on the optical fiber sensor 71 via the measuring device 72. do. Then, as the casting work of the concrete 3 progresses, the inside of the underground hole 1 gradually changes from the state filled with the stabilizing liquid 2 to the state filled with the concrete 3.

After the work of placing the concrete 3 in the underground hole 1 as described above, the concrete 3 was placed in the optical fiber sensor 71 at the time when the initial temperature was set, that is, in the state where the entire length was in contact with the stabilizer 2. The amount of expansion and contraction of the optical fiber sensor 71 after that is measured by the measuring device 72. Then, from the measured expansion and contraction amount, the temperature change from the initial temperature is continuously calculated along the length direction of the optical fiber sensor 71.

The measurement position for measuring the temperature change on the optical fiber sensor 71 can be set to a minimum pitch of 1 mm, but in the filling confirmation device 6, the measurement position on the optical fiber sensor 71 is set to the pile length. It is preferable to set an arbitrary pitch of 1 cm or more and 5 cm or less accordingly.

<Third step>
As described above, it is known that the stabilizer 2 and the concrete 3 have different temperatures, and the concrete 3 generally exhibits a higher temperature than the stabilizer 2. Therefore, when a temperature rise above a certain level is confirmed from the temperature change calculated by the measuring device 72, the temperature rise of the optical fiber sensor 71 extending in the depth direction of the underground hole 1 is confirmed. At the measurement position, it is determined that the state in which the stabilizer 2 is in contact is replaced with the state in which the concrete 3 is in contact, that is, the concrete 3 is filled.

On the other hand, if the temperature does not reach a certain level even if the temperature rises, there is no temperature change, or a temperature drop is confirmed, the measurement position is not filled with concrete 3 and the optical fiber. It is possible to determine that the stabilizer 2 is still in contact with the sensor 71, or that the optical fiber sensor 71 has a problem. The temperature rise above a certain level, which can be determined to be filled with concrete 3, may be appropriately set according to the outside air temperature, the temperature of the stabilizing liquid 2, the temperature of the concrete 3, and the like.

Therefore, in each of the plurality of optical fiber sensors 71, when there is a measurement position where contact with the concrete 3 is not confirmed, the position in the plan view of the optical fiber sensor 71 in the underground hole 1 and the position on the optical fiber sensor 71 Based on the depth of the underground hole 1 corresponding to the measurement position of, the position where the filling defect of the concrete 3 occurs in the underground hole 1 and the range thereof can be specified. As a result, the work manager can implement countermeasures suitable for the situation, such as adding concrete 3 or using a concrete vibrator, depending on the position and scale of the poor filling.

Further, as described above, the underground hole 1 has a three-dimensional shape similar to the hole wall 11 formed by the plurality of optical fiber sensors 71, coaxial with the underground hole 1, and the hole wall 11 and the reinforcing bar cage 4. Is formed between and. Therefore, before the concrete 3 is hardened by aggregating the measurement positions where the temperature rise is confirmed in each of the plurality of optical fiber sensors 71, that is, the measurement positions determined to be in contact with the concrete 3 on the optical fiber sensor 71. At this stage, it is also possible to grasp the rough shape of the cast-in-place pile to be constructed.

As a result, it is possible to evaluate whether or not the estimated finished shape satisfies the management standard at the stage where the concrete 3 placed in the underground hole 1 is uncured. Therefore, even if it is determined that the control standard is not satisfied, it is possible to implement countermeasures to satisfy the standard at an early stage. Further, when re-construction is required, complicated labor such as removing the underground structure after hardening becomes unnecessary, and the work process can be significantly shortened.

The following experiment was conducted in order to verify the concrete filling confirmation method using the filling confirmation device 6 having the above-described configuration.

Specifically, as shown in FIG. 5, the reinforcing bar cage 4 has a first region 41 in which the main reinforcing bars are sparsely arranged (in this experiment, a single reinforcing bar is adopted) and the main reinforcing bars are densely arranged (in this experiment, a single reinforcing bar is adopted). In this experiment, it was manufactured so as to have a second region 42 in which double reinforcing bars were adopted). Then, one optical fiber sensor 711 extends in the depth direction of the underground hole 1 via the connecting member 5 in the first region 41 which is the outer peripheral surface of the reinforcing bar cage 4 and has sparse reinforcement arrangement. To install. Similarly, one optical fiber sensor 712 is installed via the connecting member 5 in the second region 42 where the reinforcement is densely arranged.

As described above, the reinforcing bar cage 4 in which the two optical fiber sensors 711 and 712 are arranged is built in the underground hole 1 filled with the stabilizer 2, and then the filling status of the concrete 3 is confirmed according to the above-mentioned procedure. .. In the present embodiment, concrete is placed in the underground hole 1 in four steps, and each time the concrete is placed, the initial temperature is continuously used as a reference along the length direction of the optical fiber sensor 71. The temperature change was measured.

In this verification experiment, the pile dimensions were 2.3 m in diameter and 3.5 m in length, the optical fiber sensors 711 and 712 had a diameter of 0.25 mm, and the protective tube 74 of the optical fiber sensors 711 and 712 had a diameter of 2.0 mm. The temperature change was measured at a pitch of 2 cm along the length direction of the optical fiber sensor 71 with reference to the initial temperature.

Further, when confirming the filling status of the concrete 3, when the optical fiber sensors 711 and 712 confirmed a temperature rise of 1 ° C. or higher, it was determined that the concrete 3 was in contact with the stabilizing liquid 2 at the measurement position.

Further, as shown in FIG. 5, the concrete 3 is placed to a depth of about 1.9 m in the first time, to a depth of about -1.2 m in the second time, and to a depth of about -1.2 m in the third time. Concrete 3 with a capacity sufficient for casting up to about −0.3 m and extra filling until it reached a position higher than the ground surface in the 4th time was cast.

FIG. 6A shows the underground hole 1 after each of the first to fourth concrete placing operations in the optical fiber sensor 712 installed in the second region 42 in which the main bars are densely arranged. Shows the temperature change in the depth direction. Looking at the temperature change after the first placement, there is a temperature rise of about 1.5 ° C at a depth of about -2.5 m, and the reinforcing bar cage 4 and the hole wall 11 are from the bottom of the hole to the point of about -2.5 m. It can be seen that the concrete 3 is filled between the two.

Next, after the second casting, there is a temperature rise of about 1 ° C to 1.6 ° C at a depth of about -1.5 m or deeper, and the reinforcing bar cage 4 and the hole wall 11 reach a point about -1.5 m from the bottom of the hole. It can be seen that the concrete 3 is filled between the two. In addition, after the 3rd and 4th casting, there is a temperature rise of about 1 ° C to 2 ° C to a depth of about -0.5 m or deeper, and the reinforcing bar cage 4 and the hole wall are reached from the bottom of the hole to a point of about -0.5 m. It can be seen that the concrete 3 is filled between the 11 and 11.

In this way, as the number of castings increases, the temperature rise can be confirmed from the bottom of the hole toward the ground surface in the underground hole 1, and the space between the reinforcing bar cage 4 and the hole wall 11 gradually changes from the stabilizing liquid 2 to concrete. You can see how it is being replaced by 3.

Similarly, in FIG. 6B, in the optical fiber sensor 711 installed in the first region 41 in which the main bars are sparsely arranged, in the ground after the first to fourth concrete placing operations. The temperature change in the depth direction of the hole 1 is shown. Looking at the temperature change after the first placement, there was a temperature rise of about 1.5 ° C to a depth of about -2.3 m or deeper, and the reinforcing bar cage 4 and the hole wall 11 were found from the bottom of the hole to a point of about -2.3 m. It can be seen that the concrete 3 is filled between the two.

Next, after the second casting, there was a temperature rise of about 1 to 1.5 ° C at a depth of about -1.3 m or deeper, and the reinforcing bar cage 4 and the hole wall 11 reached a point about -1.3 m from the bottom of the hole. It can be seen that the concrete 3 is filled between the two. In addition, after the third casting, there is a temperature rise of about 1 ° C to 2 ° C at a depth of about -0.4 m or deeper, and between the reinforcing bar cage 4 and the hole wall 11 from the bottom of the hole to a point of about -0.4 m. It can be seen that the concrete 3 is filled in.

Furthermore, in the optical fiber sensor 711, when looking at the temperature change after the fourth casting, that is, after the extra filling, there is a temperature rise of about 1.5 ° C to 2.4 ° C at a depth of about −0.3 m or more. It can be seen that the concrete 3 is filled between the reinforcing bar cage 4 and the hole wall 11 from the bottom of the hole to a point of about −0.3 m.

As described above, according to the concrete filling confirmation method using the filling confirmation device 6, the concrete 3 placed in the underground hole 1 is an optical fiber arranged in the second region 42 in which the main reinforcing bars are densely arranged. In the vicinity of the sensor 712, at least to a height of about -0.5 m from the bottom of the hole, and in the vicinity of the optical fiber sensor 711 arranged in the first region 41 with sparsely arranged main bars, at least -0. It can be confirmed that the concrete 3 is filled between the reinforcing bar cage 4 and the hole wall 11 up to a height of about 3 m.

By the way, looking at the graph of the temperature change after the 4th casting from FIGS. 6 (a) and 6 (b), the temperature rise with respect to the initial temperature progresses at almost all depths as compared with the case after the 3rd casting. You can see how it is.

This is because the top edge of the concrete 3 in the underground hole 1 becomes higher as the number of times the concrete 3 is cast increases, so that the concrete 3 makes the hole wall 11 by its own weight at each depth of the underground hole 1. The filling range is expanded in the pushing direction, that is, on the outer peripheral surface side of the hole wall 11 side of the optical fiber sensor 712. As a result, the cover thickness of the concrete 3 with respect to the optical fiber sensors 711 and 712 is increased. Therefore, it can be assumed that the optical fiber sensors 711 and 712 capture the temperature of the concrete 3 more efficiently than when the cover thickness is small. ..

Then, the graph showing the temperature change after the fourth casting, which is the final casting of the concrete 3, not only shows whether or not the concrete 3 has come into contact with the optical fiber sensors 711 and 712. It can be said that the thickness of the concrete 3 in the optical fiber sensors 711 and 712 is reflected, that is, the outer shape of the concrete 3 filled in the underground hole 11 in the depth direction is reflected in more detail.

As described above, in the concrete filling confirmation method in the present embodiment, the optical fiber sensor 71 extending in the depth direction is secured at a certain distance from each of the hole wall 11 of the underground hole 1 and the reinforcing bar cage 4. Cast-in-place piles to be constructed by arranging a plurality of holes at regular intervals in the circumferential direction of the hole wall 11 and plotting the temperature change for each measurement position on the optical fiber sensor 71 obtained from each of these optical fiber sensors 71. It is also possible to estimate the finished shape of the concrete with higher accuracy.

The concrete vibrator 1 of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the present embodiment, the filling confirmation device 6 is configured to use a plurality of optical fiber sensors 71, but the present invention is not necessarily limited to this. Only one optical fiber sensor 71 may be used, and the optical fiber sensor 71 may be provided only at a position where the filling status of the concrete 3 in the underground hole 1 is desired to be confirmed.

Further, the installation position of the optical fiber sensor 71 in the underground hole 1 is not limited at all. For example, one optical fiber sensor 71 may be arranged so as to cover the entire surface of the hole wall 11 while being folded back in the height direction. Further, in order to confirm the filling status of the concrete 3 inside and outside the reinforcing bar cage 4, the optical fiber sensors 71 may be installed in both the vicinity of the outer peripheral surface and the vicinity of the inner peripheral surface of the reinforcing bar cage 4.

Further, in the present embodiment, the optical fiber sensor 71 is covered with a protective tube 74 made of stainless steel and then arranged in the underground hole 1. However, the present invention is not necessarily limited to this, and any material such as an aluminum tube or a metal tube having thermal conductivity capable of transferring the heat of the contact material 9 while protecting the optical fiber sensor 71 will be used. A protective tube 74 made of the above material may be adopted. Further, the shape of the protective tube 74 is not limited at all, and any shape such as a straight tube or a spiral tube is adopted as long as it can protect the optical fiber sensor 71 to the extent that external pressure does not act on it. May be good.

Further, the optical fiber sensor 71 is connected to the reinforcing bar cage 4 by the connecting member 5 made of synthetic resin, but the present invention is not necessarily limited to this, and heat is transferred from the reinforcing bar cage 4 to the optical fiber sensor 71. As long as the distance between the reinforcing bar cage 4 and the hole wall 11 and the optical fiber sensor 71 can be kept constant even if the lateral pressure of the concrete 3 or the water pressure of the stabilizer 2 is applied. The material and shape of the above may be adopted.

1 Underground hole 11 Hole wall 2 Stabilizer 3 Concrete 4 Reinforcing bar cage 41 First area 42 Second area 5 Connecting member 6 Filling confirmation device 7 Optical fiber sensing system 71 Optical fiber sensor 711 Optical fiber sensor (first area) Placed at 41)
712 Fiber Optic Sensor (Located in Second Region 42)
711 Protective tube 72 Measuring device 73 Output device 74 Protective tube 8 Connector 9 Contact 10 Tremy tube

Claims (2)

The filled with stabilizing solution ground hole, stable in contact while ensuring a predetermined distance from the hole wall a plurality of optical fiber sensors The rewritable installed spaced in a circumferential direction of the bore wall, the optical fiber sensor The first step of setting the temperature of the liquid to the initial temperature and
After placing the concrete, the amount of expansion and contraction of the optical fiber sensor after the concrete is placed with respect to the time when the initial temperature is set is detected, and the temperature change from the initial temperature is measured based on the amount of expansion and contraction. The second step of measuring at least one point on the fiber sensor, and
At the measurement position of the optical fiber sensor in which the temperature rise is confirmed based on the temperature change, it is determined that the concrete has come into contact with the optical fiber sensor, and the underground hole is formed based on the determined measurement position. The third step of estimating the finished shape of the underground structure to be constructed, and
A method for confirming the filling of concrete, which comprises. In the concrete filling confirmation method according to claim 1,
In the first step, filling concrete is provided in a reinforcing bar cage to be built in the underground hole by arranging the optical fiber sensor while securing a predetermined distance from the reinforcing bar cage via a connecting member. Confirmation method.

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