Ground condition measurement method

Abstract

To provide a ground state measurement method capable of properly grasping an injection situation of a grout material in the ground.SOLUTION: A ground state measurement method includes: a grouting step of injecting a grout material G into a bore hole H formed in the ground B; an optical fiber sensor temperature measurement step of measuring a temperature of the ground B by an optical fiber cable 11 extending in the ground B; and a grout material injection determination step of determining whether or not the grout material G is permeated from the bore hole H to a point where the optical fiber cable 11 is arranged using the temperature measured by the optical fiber cable 11.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a ground condition measurement method for measuring the condition of the ground into which grout material is injected.

Background Art

[0002] Patent Document 1 describes an injection device for injecting grout material into a boring hole formed in a foundation ground. The injection device is used for grouting in dam construction. In grouting in dam construction, grout material is injected into a plurality of primary boring holes. Next, grout material is injected into secondary boring holes formed between the plurality of primary boring holes.

[0003] Before injecting the grout material into the primary boring holes and the secondary boring holes, the measurement of the radon value in the primary boring holes and the secondary boring holes is performed. The radon value is used for evaluating the water impermeability or strength in the foundation ground. When the radon value in the secondary boring hole does not satisfy the reference value, after injecting the grout material into the secondary boring hole, grout material is injected into the tertiary boring holes respectively formed between the primary boring hole and the secondary boring hole.

[0004] The injection device includes a pump for delivering the grout material to an injection pipe and a control valve for controlling the flow of the grout material in the injection pipe. Further, the injection device includes an optical fiber cable installed in the foundation ground, a strain measurement unit connected to one end of the optical fiber cable for measuring the strain of the optical fiber cable, and a controller to which a signal from the strain measurement unit is input.

[0005] The distortion measurement unit measures the distortion at a plurality of positions in the optical fiber cable installed in the foundation ground. The controller calculates the displacement amount of the foundation ground from the measured distortion, and controls the pump and the control valve according to the displacement amount. Since the optical fiber cable is partially distorted according to the displacement of the foundation ground, the grout material is injected according to the displacement of the foundation ground. Therefore, even when displacement occurs only inside the foundation ground, the grout is injected into the foundation ground at an appropriate pressure and amount. This makes it possible to prevent the destruction of the foundation ground and enhance the water barrier property and strength of the foundation ground.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the injection device described above, the distortion measurement unit measures the distortion of the optical fiber cable, and the controller controls the injection of the grout according to the displacement amount of the foundation ground calculated from the distortion. By the way, if the flow or injection range of the grout material inside the ground cannot be appropriately grasped, there is a concern that the effect of grouting will decrease. Therefore, in order to enhance the effect of grouting, it is required to be able to appropriately grasp the injection state of the grout material inside the ground.

[0008] An object of the present disclosure is to provide a ground state measurement method capable of appropriately grasping the injection state of the grout material inside the ground.

Means for Solving the Problems

[0009] The ground condition measurement method according to one aspect of the present disclosure includes: (1) a grouting step of injecting a grout material into a boring hole formed in the ground; an optical fiber sensor temperature measurement step of measuring the temperature of the ground by using an optical fiber cable extending inside the ground; and a grout material injection determination step of determining whether the grout material has penetrated from the boring hole to the location where the optical fiber cable is disposed, using the temperature measured by the optical fiber cable.

[0010] In this ground condition measurement method, in the grouting step, a grout material is injected into a boring hole formed in the ground. An optical fiber cable extends inside the ground, and in the optical fiber temperature measurement step, the temperature of the ground is measured by this optical fiber cable. The temperature measured by the optical fiber cable is used to determine whether the grout material has penetrated from the boring hole to the location where the optical fiber cable is disposed. That is, it is determined whether the grout material has penetrated to the location where the optical fiber cable is disposed, using the temperature measured by the optical fiber cable. Therefore, since the flow of the grout material inside the ground can be grasped from the measured temperature change inside the ground, the flow and position of the grout material inside the ground can be appropriately grasped. Thus, the effect of grouting can be enhanced.

[0011] (2) In the above (1), in the optical fiber sensor temperature measurement step, a plurality of optical fiber cables disposed at a plurality of positions in the ground may measure the respective temperatures of the plurality of positions. The ground condition measurement method may include a reach range determination step of determining the injection reach range of the grout material, using the respective temperatures of the plurality of positions. In this case, optical fiber cables are disposed at respective ones of a plurality of different positions inside the ground, and the plurality of optical fiber cables measure the temperatures of the respective positions. The injection reach range of the grout material is determined from the respective temperatures of the plurality of positions. Therefore, since the injection reach range of the grout material can be grasped from the temperatures measured by the plurality of optical fiber cables, the flow and position of the grout material inside the ground can be grasped more appropriately.

[0012] (3) In the above (1) or (2), in the grouting process, grout material that has been heated or cooled may be injected. In this case, when the heated or cooled grout material is injected, the internal temperature change of the ground when the grout material penetrates becomes more prominent. Therefore, by measuring this temperature change using an optical fiber cable, the flow and position of the grout material inside the ground can be grasped more appropriately. Thus, the effect of grouting can be further enhanced.

[0013] (4) In any of the above (1) to (3), the ground condition measurement method may include a water injection test step of performing a water injection test on a boring hole, and a water injection test temperature measurement step of measuring the temperature of the ground by an optical fiber cable while the water injection test is being performed. In the grout material injection determination step, it may be determined whether the grout material penetrates from the boring hole to the point where the optical fiber cable is arranged using the temperature measured by the optical fiber cable. In this case, it is possible to determine whether the grout material reaches the water path during grouting.

[0014] The ground condition measurement method according to another aspect of the present disclosure includes: (5) a water injection test step of performing a water injection test on a boring hole formed in the ground; a water injection test temperature measurement step of measuring the temperature of the ground by an optical fiber cable extending inside the ground while the water injection test is being performed; and a grout material injection determination step of determining whether the grout material penetrates from the boring hole to the point where the optical fiber cable is arranged using the temperature measured by the optical fiber cable.

[0015] In this ground condition measurement method, in the water injection test process, a water injection test is performed on a boring hole formed in the ground. An optical fiber cable extends inside the ground, and the temperature of the ground is measured by this optical fiber cable. The temperature measured by the optical fiber cable is used to determine whether the grout material penetrates from the boring hole to the point where the optical fiber cable is arranged. That is, it is determined whether the grout material penetrates to the point where the optical fiber cable is arranged by using the temperature measured by the optical fiber cable. Therefore, since the flow of the grout material inside the ground can be grasped from the measured temperature change inside the ground, the flow and position of the grout material inside the ground can be appropriately grasped.

Effect of the Invention

[0016] According to the present disclosure, the injection state of the grout material inside the ground can be appropriately grasped.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the ground condition measurement method according to the present disclosure will be described with reference to the drawings. The same or corresponding elements in the description of the drawings are denoted by the same reference numerals, and redundant descriptions are omitted as appropriate. In addition, the drawings may be drawn with some parts simplified or exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those described in the drawings.

[0019] FIG. 1 is a longitudinal sectional view showing the ground B of an exemplary site A1 to which the ground condition measurement method according to the present embodiment is applied. As an example, the site A1 is a dam construction site, and the ground B is a natural ground. In the ground B, a grouting hole H into which a grout material G is injected is formed. The grouting hole H extends in the vertical direction D1. By injecting the grout material G into the grouting hole H, grouting of the ground B at the site A1 is performed. In grouting, if the injection state of the grout material G inside the ground B is not appropriate, problems such as insufficient injection of the grout material G and inability to improve the water blocking property, insufficient strength, or uplift of the ground B may occur. Therefore, at the site A1, it is required to appropriately grasp the injection state of the grout material G.

[0020] The grout material G is injected into the grouting hole H from a position a predetermined distance C (for example, 0.2 m) below the ground S of the site A1. For example, the grout material G is heated or cooled. The temperature of the grout material G injected into the grouting hole H is, for example, about 25°C. For example, since the temperature of the groundwater in the ground B is about 15°C, the temperature of the grout material G to be injected is higher than the temperature of the ground B and the groundwater in the ground B before the grout material G is injected.

[0021] In the ground B, an observation hole K for observing the injection state of the grout material G is formed. The observation hole K is a vertical boring hole extending in the vertical direction D1 at a position separated from the boring hole H. An optical fiber cable 11 is passed through the observation hole K. The optical fiber cable 11 is an optical fiber sensor capable of measuring the temperature and strain of the ground B. The optical fiber cable 11 is, for example, an element of an injection state grasping system 1 for grasping the injection state of the grout material G. In the injection state grasping system 1, the injection state of the grout material G is grasped by the optical fiber cable 11 measuring the temperature (including temperature changes) of the ground B.

[0022] For example, the injection state grasping system 1 includes an injection pressure measuring unit 2 for measuring the injection pressure of the grout material G with respect to the boring hole H, and an injection flow rate measuring unit 3 for measuring the flow rate of the grout material G injected into the boring hole H. Further, the injection state grasping system 1 includes an optical fiber cable 11 and a measuring instrument 12 provided at the end of the optical fiber cable 11. The measuring instrument 12 measures the temperature of the ground B using the optical fiber cable 11. The measuring instrument 12 inputs measurement light to the optical fiber cable 11, and for example, the backward scattered light generated from the optical fiber cable 11 by the input of the measurement light is input to the measuring instrument 12. The measuring instrument 12 measures the change in the spectrum of the input backward scattered light to measure the temperature of the ground B around the optical fiber cable 11.

[0023] FIG. 2(a) is a plan view and a longitudinal sectional view schematically showing a specific example of the site A1. As an example, in the site A1, a main curtain which is a ground improvement area by the grout material G is constructed. As shown in FIG. 2(a), a plurality of boring holes (injection holes) H and a plurality of observation holes K are formed in the site A1. In this case, the injection state grasping system 1 includes a plurality of optical fiber cables 11 inserted into each of the plurality of observation holes K. The plurality of optical fiber cables 11 include a temperature measurement optical fiber cable 11b and a strain measurement optical fiber cable 11c inserted into the observation hole K.

[0024] The measuring instrument 12 measures the strain of the ground B by, for example, Rayleigh measurement using the strain measurement optical fiber cable 11c. However, the measuring instrument 12 may measure the strain by Brillouin measurement using the strain measurement optical fiber cable 11c. When the measuring instrument 12 inputs the measurement light into the strain measurement optical fiber cable 11c, backward scattered light is generated in the strain measurement optical fiber cable 11c. The spectrum (intensity for each frequency) of this backward scattered light changes due to the strain. The intensity of the backward scattered light is smaller than the intensity of the measurement light.

[0025] In Rayleigh measurement, the strain generated in the strain measurement optical fiber cable 11c is detected by measuring the change in the spectrum of the backward scattered light. Rayleigh measurement using the backward scattered light has the advantages of high accuracy and being resistant to light loss. In the strain measurement optical fiber cable 11c, for example, it is possible to detect the strain of the ground B with an accuracy of 1 μ strain. The temperature measurement optical fiber cable 11b can similarly detect the temperature of the ground B with high accuracy. Furthermore, the strain and temperature of the ground B can be continuously measured during grouting.

[0026] For example, the plurality of optical fiber cables 11 includes the conductor optical fiber cable 11d, and each of the temperature measurement optical fiber cable 11b and the strain measurement optical fiber cable 11c is connected to the measuring instrument 12 via the conductor optical fiber cable 11d. The measuring instrument 12 is provided, for example, inside a measurement hut installed on the ground S. The injection situation grasping system 1 includes, for example, a weight 13 attached to the end (lower end) of the optical fiber cable 11 opposite to the measuring instrument 12. With this weight 13, the installation of the optical fiber cable 11 into the observation hole K can be easily performed.

[0027] The plurality of boring holes H include, for example, a pilot hole H1, a primary hole H2, and a secondary hole H3. At the site A1, a plurality of pilot holes H1 are arranged in a predetermined direction D2, and a primary hole H2 is formed between two pilot holes H1 in a plan view. Then, a secondary hole H3 is formed between the pilot hole H1 and the primary hole H2. After the radon value of the pilot hole H1 is measured, the pilot hole H1 is filled with the grout material G, and after the radon value of the primary hole H2 is measured, the primary hole H2 is filled with the grout material G. And the radon value is measured before the grout material G is injected into the secondary hole H3.

[0028] The radon value is used for evaluating the water barrier property or strength in the ground B. The test for measuring the radon value is also called a water injection test. In the measurement of the radon value, for example, a water pressure of 1 MPa is applied to the boring hole, and the amount of water penetrating into the ground B in a 1 m region of the boring hole per minute is measured. When the radon value of the secondary hole H3 satisfies the reference value, the secondary hole H3 is filled with the grout material G. On the other hand, when the radon value of the secondary hole H3 does not satisfy the reference value, after the secondary hole H3 is filled with the grout material G, a tertiary hole H4 is drilled between the primary hole H2 (or the pilot hole H1) and the secondary hole H3, and the tertiary hole H4 is filled with the grout material G.

[0029] As an example, the number of observation holes K formed at the site A1 is 3 or more. For example, the observation hole K is formed at a position separated in the direction D3 with respect to a virtual reference line X connecting the primary hole H2 and the secondary hole H3. The direction D3 is a direction intersecting both the vertical direction D1 and the direction D2. As an example, the observation hole K is formed at a position separated in the direction D3 from the midpoint of the line segment connecting the primary hole H2 (or the pilot hole H1) and the secondary hole H3 (the position where the tertiary hole H4 is formed).

[0030] The above has described the specific example of Site A1. However, the sites to which the injection situation grasping system 1 and the ground condition measurement method according to the embodiment can be applied are not limited to Site A1. FIG. 2(b) is a plan view schematically showing Site A2 different from Site A1 in FIG. 2(a). As an example, an auxiliary curtain of a dam is constructed at Site A2. Site A2 is, for example, divided into a plurality of blocks R, and a plurality of primary holes H2, a plurality of secondary holes H3, and a plurality of observation holes K are formed in each block R.

[0031] For example, the primary holes H2 are formed to be arranged in a staggered pattern along each of the directions D2 and D3. And, as described above, after the measurement of the radon value is performed on the primary holes H2, the primary holes H2 are filled with the grout material G. Thereafter, secondary holes H3 are formed between two primary holes H2 arranged along the direction D2 and between two secondary holes H3 arranged along the direction D3, respectively, and the measurement of the radon value is performed on the secondary holes H3. And the secondary holes H3 are filled with the grout material G. Further, when the radon value of the secondary holes H3 does not satisfy the reference value, tertiary holes H4 are formed as described above.

[0032] The observation holes K are formed, for example, at each corner (for example, the four corners) of each block R and near the center of each block R. For example, the observation holes K are formed at the midpoint positions of virtual line segments connecting the primary holes H2 and the secondary holes H3. As described above, the optical fiber cable 11 is inserted into each observation hole K, and the injection situation grasping system 1 measures the injection situation of the grout material G in the ground B by measuring the temperature of the ground B with the optical fiber cable 11.

[0033] Next, the steps of the ground condition measurement method according to the present embodiment will be described with reference to the flowchart of FIG. 3. FIG. 3 is a flowchart showing an example of the steps of the ground condition measurement method according to the present embodiment. The ground condition measurement method according to the present embodiment is performed, for example, using the injection situation grasping system 1. First, the grout material G to be injected into the boring hole H is heated or cooled (step of heating or cooling the grout material). At this time, for example, the grout material G is heated (or cooled) to a predetermined temperature (for example, 25°C).

[0034] Also, as shown in FIG. 1, for example, a boring hole H is formed in the ground B, and an observation hole K is formed at a position separated from the boring hole H in the ground B (step of forming the observation hole). Then, an optical fiber cable 11 is inserted into the observation hole K to install the injection situation grasping system 1 (step of inserting the optical fiber cable).

[0035] Then, a water injection test is performed (water injection test step). Specifically, the radon value is measured for the boring hole H. At this time, the water path in the ground B is measured, and the temperature of the ground B is measured by the optical fiber cable 11 (water injection test temperature measurement step). FIG. 4(a) shows the time-series data of the injection pressure and injection flow rate during the water injection test. In the graph of FIG. 4(a), the injection pressure is indicated by a broken line and the injection flow rate is indicated by a solid line. FIG. 4(b) is a graph showing the temperature distribution of the ground B during the water injection test. As shown in FIGS. 4(a) and 4(b), the location of the water path in the ground B can be specified from the temperature measured by the optical fiber cable 11. In the example of FIG. 4(b), it can be seen that there is a water path at a location where the depth from the hole opening is 2.5 m to 4.5 m.

[0036] Next, grouting is performed by injecting the grout material G heated (or cooled) into the boring hole H (grouting step, step S1). As shown in Fig. 5(a), along with the grouting, the injection pressure measuring unit 2 measures the injection pressure of the grout material G into the boring hole H, and the injection flow rate measuring unit 3 measures the injection flow rate per unit time of the grout material G into the boring hole H. Fig. 5(a) is a graph showing the time-series data of the injection pressure and injection flow rate of the grout material G in one boring hole H. Actually, the injection pressure and injection flow rate are measured for each of the plurality of boring holes H.

[0037] As shown in Fig. 5(b), the optical fiber cable 11 extending inside the ground B measures the temperature of the ground B (optical fiber sensor temperature measurement step). Fig. 5(b) is the time-series data of the temperature of the ground B obtained by the optical fiber cable 11 inserted into the observation hole K.

[0038] As shown in Figs. 5(a) and 5(b), the temperature at the position (observation hole K) where the optical fiber cable 11 of the ground B is arranged gradually increases from the start of injection of the grout material G into the boring hole H. The injection flow rate per unit time of the grout material G significantly increases immediately after injection and then gradually decreases. The injection pressure of the grout material G increases immediately after injection and then becomes constant.

[0039] For example, when the injection flow rate per unit time of the grout material G becomes 0, the injection of the grout material G into the boring hole H becomes impossible and ends. The measuring instrument 12 calculates the difference (hereinafter referred to as the temperature change amount) between the temperature of the ground B at the end of injection of the grout material G measured by the optical fiber cable 11 and the temperature of the ground B at the start of injection of the grout material G measured by the optical fiber cable 11. Then, the measuring instrument 12 determines whether the grout material G has penetrated to the observation hole K (the point where the optical fiber cable 11 is arranged) from the temperature change amount (grout material injection determination step).

[0040] The grout material injection determination step may be executed based on the location of the water path specified during the water pressure test. Specifically, using the temperature distribution of the ground B obtained during the water pressure test, it may be determined whether the grout material G penetrates from the boring hole H to the point where the optical fiber cable 11 is disposed. For example, the temperature distribution measured by the optical fiber cable 11 during grouting may be compared with the temperature distribution measured by the optical fiber cable 11 during the water pressure test to determine whether the grout material G has penetrated. FIG. 6 shows an example of the temperature distribution measured by the optical fiber cable 11 during grouting. As shown in FIGS. 6 and 4(b), as an example, it may be determined that the grout material G has penetrated when the temperature distribution during grouting approximates the temperature distribution during the water pressure test.

[0041] FIG. 7 is a graph showing the relationship between the amount of temperature change observed by each of a plurality of observation holes K and the distance from the boring hole H to the observation hole K. As illustrated in FIGS. 2(b) and 7, the closer the observation hole K is to the boring hole H, the greater the amount of temperature change. As a specific example, the amount of temperature change is large at the observation holes K6 and K8 closest to the boring hole H, and the amount of temperature change is small at the observation holes K1 and K3 far from the boring hole H.

[0042] For example, the measuring instrument 12 determines the injection reach range of the grout material G using the amount of temperature change of each of the plurality of observation holes K measured by each optical fiber cable 11 (reach range determination step, step S2). As a specific example, the measuring instrument 12 has a threshold value V of the amount of temperature change (0.5°C as an example), and determines that the grout material G has reached up to the observation holes K6, K7, and K8 that exceed the threshold value V among the plurality of observation holes K. As an example, the measuring instrument 12 determines that the grout material G has reached within a range of 10 m from the boring hole H. The above reach determination step is executed, for example, for each of the boring holes H shown in FIG. 2(b).

[0043] After the injection reach range of the grout material G is determined, the amount of temperature change with respect to the distance from the boring hole H is arranged (step S3). Then, it is determined which of the current specification and the modified specification of the boring hole H has a higher injection effect of the grout material G (step S4). "Specification" indicates, for example, the number and arrangement of the boring holes H, the injection pressure of the grout material G, or the material of the grout material G. The current specification indicates at least any one of the current number and arrangement of the boring holes H, the current injection pressure of the grout material G, and the current material of the grout material G. The modified specification indicates the specification after changing at least any one of the number and arrangement of the boring holes H, the injection pressure of the grout material G, and the material of the grout material G.

[0044] In this embodiment, for example, the injection effect of the grout material G is determined while changing the specification. As an example, when the reach distance of the grout material G from the boring hole H in the modified specification is longer than the reach distance of the grout material G from the boring hole H in the current specification, it is determined that the modified specification has a higher injection effect. In this case, the specification is switched to the modified specification (step S5), and a series of steps are completed.

[0045] On the other hand, when the reach distance of the grout material G from the boring hole H in the modified specification is less than or equal to the reach distance of the grout material G from the boring hole H in the current specification, it is determined that the injection effect of the modified specification is less than or equal to that of the current specification. In this case, the specification is kept as the current specification (step S6), and a series of steps are completed. As described above, by repeating the drilling of the boring hole H, the injection of the grout material G, and the measurement by the optical fiber cable 11 while changing the specification, grouting can be carried out reasonably. In some cases, it is also possible to reduce the number of boring holes H.

[0046] Next, the effects obtained from the ground condition measurement method according to the present embodiment will be described in more detail. As shown in FIG. 1, in the ground condition measurement method according to the present embodiment, in the grouting step, a grout material G is injected into a boring hole H formed in the ground B. An optical fiber cable 11 extends inside the ground B, and in the optical fiber temperature measurement step, the temperature of the ground B is measured by the optical fiber cable 11. The temperature measured by the optical fiber cable 11 is used to determine whether the grout material G has penetrated from the boring hole H to the location where the optical fiber cable 11 is arranged (the location of the observation hole K). That is, it is determined whether the grout material G has penetrated to the location where the optical fiber cable 11 is arranged using the temperature measured by the optical fiber cable 11. Therefore, since the flow of the grout material G inside the ground B can be grasped from the measured temperature change inside the ground B, the flow and position of the grout material G inside the ground B can be appropriately grasped. Thus, the effect of grouting can be enhanced.

[0047] In the present embodiment, in the optical fiber sensor temperature measurement step, a plurality of optical fiber cables 11 arranged at a plurality of positions (for example, observation holes K1 to K8) of the ground B measure the temperature of each of the plurality of positions. The ground condition measurement method includes a reach range determination step of determining the injection reach range of the grout material G using the temperature of each of the plurality of positions. Therefore, the optical fiber cables 11 are arranged at different positions inside the ground B, and the plurality of optical fiber cables 11 measure the temperature of each position. The injection reach range of the grout material G is determined from the temperature of each of the plurality of positions. Therefore, since the injection reach range of the grout material G can be grasped from the temperatures measured by the plurality of optical fiber cables 11, the flow and position of the grout material G inside the ground B can be grasped more appropriately.

[0048] In the present embodiment, in the grouting process, grout material G that has been heated or cooled is injected. Therefore, when the heated or cooled grout material G is injected, the temperature change inside the ground B when the grout material G penetrates becomes even more prominent. Therefore, by measuring this temperature change using the optical fiber cable 11, the flow and position of the grout material G inside the ground B can be grasped more appropriately. Thus, the effect of grouting can be further enhanced.

[0049] In the present embodiment, the ground condition measurement method may include a water injection test step of performing a water injection test on the boring hole H, and a water injection test temperature measurement step of measuring the temperature of the ground B by the optical fiber cable 11 when the water injection test is being performed. In the grout material injection determination step, it may be determined whether the grout material G penetrates from the boring hole H to the point where the optical fiber cable 11 is disposed using the temperature measured by the optical fiber cable 11. In this case, it is possible to determine whether or not the grout material G reaches the water path during grouting.

[0050] The embodiments of the ground condition measurement method according to the present disclosure have been described above. However, the ground condition measurement method according to the present disclosure is not limited to the above-described embodiments, and can be appropriately changed within the scope of the gist described in the claims. That is, the content and order of the steps of the ground condition measurement method are not limited to the above-described embodiments and can be appropriately changed. Furthermore, the configuration and functions of each part of the injection situation grasping system are also not limited to the above-described embodiments and can be appropriately changed. For example, in the above-described embodiments, the ground condition measurement method applied to the sites A1 and A2, which are the dam construction sites, has been described. However, the ground condition measurement method according to the present disclosure can also be applied to sites other than the dam construction sites and can be adopted at various sites.

Explanation of Reference Numerals

[0051] 1…Injection condition monitoring system, 2…Injection pressure measurement unit, 3…Injection flow rate measurement unit, 11…Optical fiber cable, 11b…Thermometer optical fiber cable, 11c…Strain gauge optical fiber cable, 11d…Conductor optical fiber cable, 12…Measuring instrument, 13…Weight, A1, A2…Job site, B…Ground, C…Predetermined distance, D1…Vertical direction, D2, D3…Direction, G…Grout material, H…Boring hole, H1…Pilot hole, H2…Primary hole, H3…Secondary hole, H4…Tertiary hole, K, K1, K2, K3, K4, K5, K6, K7, K8…Observation hole, R…Block, S…Ground surface, V…Threshold value, X…Reference line.

Claims

1. A grouting step of injecting a grout material into a boring hole formed in the ground, an optical fiber sensor temperature measurement step of measuring the temperature of the ground by an optical fiber cable extending inside the ground, a grout material injection determination step of determining whether the grout material has penetrated from the boring hole to the point where the optical fiber cable is disposed using the temperature measured by the optical fiber cable, A ground condition measurement method comprising the above steps.

2. In the optical fiber sensor temperature measurement step, a plurality of the optical fiber cables disposed at a plurality of positions of the ground measure the temperature of each of the plurality of positions, The ground condition measurement method according to claim 1, further comprising a reach range determination step of determining the injection reach range of the grout material using the temperature of each of the plurality of positions. The ground condition measurement method according to claim 1.

3. In the grouting step, the grout material that has been heated or cooled is injected. The ground condition measurement method according to claim 1 or 2.

4. A water injection test step of performing a water injection test on the boring hole, a water injection test temperature measurement step of measuring the temperature of the ground by the optical fiber cable while the water injection test is being performed, Comprising: In the grout material injection determination step, it is determined whether the grout material has penetrated from the boring hole to the point where the optical fiber cable is disposed using the temperature measured by the optical fiber cable. The ground condition measurement method according to claim 1 or 2.

5. A water injection test step of performing a water injection test on a boring hole formed in the ground, a water injection test temperature measurement step of measuring the temperature of the ground by an optical fiber cable extending inside the ground while the water injection test is being performed, a grout material injection determination step of determining whether the grout material has penetrated from the boring hole to the point where the optical fiber cable is disposed using the temperature measured by the optical fiber cable, A ground condition measurement method comprising the above steps.

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