JP7500399B2 - Grout injection method and injection support device - Google Patents

Description

The present invention relates to a grout injection method and injection support device.

In dam construction, reinforcement (also called "grouting improvement") is carried out by injecting grout into the foundation ground to increase the water impermeability of the foundation ground. In the grout injection method disclosed in Patent Document 1, the Lugeon value of the foundation ground is first measured, and multiple injection positions for the grout material are determined based on the Lugeon value. Next, boreholes are formed at the multiple injection positions determined, and the grout material is injected into the boreholes.

JP 2016-117996 A

If boreholes are drilled only at injection positions determined based on the Lugeon value and grout is injected only at these positions, permeable cracks that can serve as water paths will remain between adjacent boreholes, and the water-tightness of the foundation ground may be insufficient. For this reason, when necessary, secondary boreholes are drilled between injection positions determined based on the Lugeon value and grout is injected into these secondary boreholes. However, there is no established method for determining whether additional grout injection is necessary, and the current situation is that more secondary boreholes are drilled and grout is injected into them than necessary.

The purpose of the present invention is to properly inject grout material into foundation ground.

The present invention provides a method for injecting grout material into foundation ground, comprising: a crack information acquisition step of acquiring information about cracks in inner walls of first and second primary boreholes formed at a distance from each other in the foundation ground; an evaluation step of evaluating the continuity of the cracks between the first and second primary boreholes based on the information about the cracks acquired in the crack information acquisition step; a permeability information acquisition step of acquiring Lugeon values in the first and second primary boreholes; a judgment step of judging whether or not grout material needs to be injected between the first and second primary boreholes based on the continuity of the cracks evaluated in the evaluation step and the Lugeon values acquired in the permeability information acquisition step; and an injection step of forming a secondary borehole between the first and second primary boreholes and injecting grout material into the secondary borehole when it is judged that injection of grout material is necessary in the judgment step. In the crack information acquisition step, the depths of the cracks in the first and second primary boreholes are respectively estimated as a first and a second depth, and in the permeability information acquisition process, a Lugeon value in the first primary borehole at the first depth and a Lugeon value in the second primary borehole at the second depth are acquired, and in the judgment process, if the evaluation process evaluates that the cracks in the first and second primary boreholes are continuous and at least one of the Lugeon value in the first primary borehole at the first depth and the Lugeon value in the second primary borehole at the second depth is equal to or greater than a predetermined threshold, it is judged that injection of grout material between the first and second primary boreholes is necessary, and if the evaluation process evaluates that the cracks in the first and second primary boreholes are not continuous or both the Lugeon value in the first primary borehole at the first depth and the Lugeon value in the second primary borehole at the second depth are less than a threshold, it is judged that injection of grout material between the first and second primary boreholes is not necessary .

The present invention also provides an injection support device for supporting the injection of grout material into foundation ground, comprising: a crack information acquisition unit for acquiring information about cracks in inner walls of first and second primary boreholes formed at a distance from each other in the foundation ground; an evaluation unit for evaluating the continuity of the cracks between the first and second primary boreholes based on the information about the cracks acquired by the crack information acquisition unit; a permeability information acquisition unit for acquiring Lugeon values in the first and second primary boreholes; and a judgment unit for judging whether or not grout material needs to be injected between the first and second primary boreholes based on the continuity of the cracks evaluated by the evaluation unit and the Lugeon values acquired by the permeability information acquisition unit, wherein the crack information acquisition unit acquires at least the depths of the cracks in the first and second primary boreholes as first and second depths, respectively, and the permeability information acquisition unit acquires the permeability of the first primary borehole at the first depth. The judgment unit obtains a Lugeon value for the first and second primary boreholes at the second depth and a Lugeon value for the second primary borehole at the second depth, and judges that injection of grout material between the first and second primary boreholes is necessary if the evaluation unit evaluates that the cracks in the first and second primary boreholes are continuous and at least one of the Lugeon value for the first primary borehole at the first depth and the Lugeon value for the second primary borehole at the second depth is equal to or greater than a predetermined threshold, and judges that injection of grout material between the first and second primary boreholes is not necessary if the evaluation unit evaluates that the cracks in the first and second primary boreholes are not continuous or both the Lugeon value for the first primary borehole at the first depth and the Lugeon value for the second primary borehole at the second depth are less than a threshold.

According to the present invention, grout material can be properly injected into the foundation ground.

FIG. 2 is a diagram for explaining an outline of a grout injection method according to an embodiment of the present invention. 1 is a block diagram showing a configuration of a grout injection support device according to an embodiment of the present invention. FIG. 3(a) is an oblique view showing an example of a primary borehole, (b) is a schematic diagram of the inner wall of the primary borehole shown in FIG. 3(a) when expanded, and (c) is a schematic diagram of a crack detection device. (a) is a diagram for explaining a method for evaluating the continuity of cracks between adjacent primary boreholes, and (b) is a flowchart showing the processing in the evaluation section. FIG. 1 is a schematic diagram of a permeability measuring device. 13 is a flowchart showing a process in a determination unit. 1 is an example of an image displayed on a display unit. 1A is a block diagram showing the configuration of a grout injection support device according to a modified example of an embodiment of the present invention, and FIG. 1B is an example of an image displayed on a display unit.

Below, a grout injection method and a grout injection support device according to an embodiment of the present invention will be described with reference to the drawings. In dam construction, grout is injected into the foundation ground to plug cracks in the foundation ground and increase water impermeability.

First, referring to Figure 1, an outline of the procedure for injecting grout material 2 into foundation ground 1 will be described. Here, as shown in Figure 1, a case will be described in which grout material 2 is injected into foundation ground 1 in which four cracks 3a, 3b, 3c, and 3d exist. In the following, when the cracks 3a, 3b, 3c, and 3d are collectively referred to, they will simply be referred to as "cracks 3."

In the method of injecting the grout material 2, first, as shown in FIG. 1(a), a number of primary boreholes 10 are formed at intervals in the foundation ground 1, and the grout material 2 is injected into the primary boreholes 10. FIG. 1(a) shows an example in which four primary boreholes 10 are formed in the foundation ground 1. In the following, the four primary boreholes 10 are also referred to as primary boreholes 11, 12, 13, and 14, in that order from the left in FIG. 1(a).

Next, as shown in FIG. 1(b), a secondary borehole 20 is formed between adjacent primary boreholes 10, and additional grout material 2 is injected into the secondary borehole 20. FIG. 1(b) shows an example in which a secondary borehole 20 is formed between primary boreholes 11 and 12, and additional grout material 2 is injected.

If secondary boreholes 20 are formed in areas where water-proofing is sufficient and additional grout material 2 is injected, more grout material 2 than necessary will be injected into the foundation ground 1, increasing the cost of constructing the dam. For this reason, it is preferable to inject additional grout material 2 into areas where water-proofing is insufficient when grout material 2 is simply injected into the primary boreholes 10.

A lack of water impermeability can occur when the grout material 2 is not distributed throughout the crack 3 simply by injecting it into the primary borehole 10, leaving part of the crack 3 unsealed in the foundation ground 1, and the degree of water permeability in the remaining crack 3 is unacceptably high.

When the crack 3 is continuous between adjacent primary boreholes 10, the grout material 2 is unlikely to penetrate the entire crack 3. Therefore, when the crack 3 is continuous between adjacent primary boreholes 10 and is a water-permeable crack, there may be a lack of water-proofing between the adjacent primary boreholes 10.

For example, in the foundation ground 1 illustrated in FIG. 1(a), crack 3a is continuous between primary boreholes 11 and 12, and crack 3d is continuous between primary boreholes 13 and 14. Therefore, if cracks 3a and 3d are highly permeable, there may be insufficient water-proofing between primary boreholes 11 and 12 and between primary boreholes 13 and 14. Since there are no continuous cracks 3 between primary boreholes 12 and 13, water-proofing is sufficient between primary boreholes 12 and 13.

As such, whether or not the injection of grout material 2 into the primary borehole 10 alone is sufficient to provide sufficient water-proofing depends on the continuity of the cracks 3 and the permeability of the cracks 3. The continuity of the cracks 3 can be evaluated from information about the cracks 3 on the inner wall of the primary borehole 10. Furthermore, the higher the permeability of the cracks 3, the higher the permeability of the primary borehole 10 that crosses the cracks 3.

Therefore, in this embodiment, information about the cracks 3 in the inner walls of adjacent primary boreholes 10 is acquired (crack information acquisition process), the continuity of the cracks 3 between adjacent primary boreholes 10 is evaluated based on the information about the cracks 3 (evaluation process), information about the permeability of adjacent primary boreholes 10 is acquired (permeability information acquisition process), and based on the continuity of the cracks 3 and the information about the permeability, the need for injection of grout material 2 between adjacent primary boreholes 10 is determined (determination process). If it is determined that injection of grout material 2 is necessary, a secondary borehole 20 is formed between adjacent primary boreholes 10 and grout material 2 is injected into the secondary borehole 20 (injection process). Therefore, if the cracks 3 remain between adjacent primary boreholes 10 and are permeable cracks, additional grout material 2 is injected between adjacent primary boreholes 10. Therefore, the grout material 2 can be appropriately injected into the foundation ground 1.

Figure 2 is a block diagram showing the configuration of an injection support device 100 for grout material 2. As shown in Figure 2, the injection support device 100 includes a controller 30 that analyzes information related to cracks 3 and information related to the permeability of the foundation ground 1, and a display unit 40 that displays the results of the analysis by the controller 30. A crack detection device 50 that detects cracks 3 and a permeability measurement device 60 that measures the permeability in the primary borehole 10 are connected to the controller 30.

The crack information acquisition process and the permeability information acquisition process are performed using a crack detection device 50 and a permeability measurement device 60, respectively. The evaluation process and the judgment process are performed using an injection support device 100. The injection process is performed by an operator who checks the results of the judgment process performed using the injection support device 100 and operates a drilling machine and an injection machine (not shown).

The controller 30 is a microcomputer that includes a CPU (Central Processing Unit) that executes a control program, a ROM (Read-Only Memory) that stores the control program executed by the CPU, and a RAM (Random Access Memory) that stores the results of CPU calculations, etc. The controller 30 may be composed of one microcomputer or multiple microcomputers.

The controller 30 functionally comprises a crack information acquisition unit 31 that acquires information about the cracks 3 in the inner wall of the primary borehole 10, an evaluation unit 32 that evaluates the continuity of the cracks 3 between adjacent primary boreholes 10 based on the information about the cracks 3, a permeability information acquisition unit 33 that acquires information about the permeability in the primary borehole 10, and a judgment unit 34 that judges whether or not to inject grout material 2 between adjacent primary boreholes 10 based on the information about the continuity and permeability of the cracks 3. The crack information acquisition unit 31, the evaluation unit 32, the permeability information acquisition unit 33, and the judgment unit 34 are virtual units that implement the functions of the controller 30.

In the following, a case will be described in which the information on the crack 3 is the strike, inclination, and depth of the crack 3, and the information on the permeability is the Lugeon value. The strike of the crack 3 is the direction in which the intersection line formed by the intersection of the crack 3 with a virtual horizontal plane extends, and the inclination of the crack 3 is the degree of inclination of the crack 3 with respect to the virtual horizontal plane. The depth of the crack 3 in the primary borehole 10 is the distance from the intersection of the central axis of the primary borehole 10 and the crack 3 to the ground surface. The Lugeon value is a value calculated based on the injection pressure and injection flow rate when water is injected into the primary borehole 10, and a higher Lugeon value means a higher permeability of the primary borehole 10.

First, the acquisition of the strike, dip, and depth of the crack 3 by the crack information acquisition unit 31 will be described with reference to Figures 2 and 3. Figure 3(a) is an oblique view showing an example of a primary borehole 10, and Figure 3(b) is a schematic diagram of the inner wall of the primary borehole 10 shown in Figure 3(a) when unfolded. In Figures 3(a) and (b), E, W, S, and N are directions (east, west, south, and north).

As shown in FIG. 3(a), the color of the inner wall of the primary borehole 10 is different between the area with the crack 3 and the area without the crack 3, and the crack 3 forms an approximately elliptical shape on the inner wall of the primary borehole 10. As shown in FIG. 3(b), in the development of the inner wall of the primary borehole 10, the crack 3 forms a shape similar to a sine curve. The shape (amplitude and phase of the sine curve) and position of the crack 3 in the development are determined based on the strike, dip and depth of the crack 3.

In this embodiment, the crack detection device 50 shown in FIG. 3(c) is used to generate an unfolded image of the inner wall of the primary borehole 10 and extract a sine curve to detect the strike, inclination, and depth of the crack 3 in the inner wall of the primary borehole 10. The detection of the strike, inclination, and depth of the crack 3 by the crack detection device 50 is performed before the grout material 2 is injected into the primary borehole 10.

Figure 3(c) is a schematic diagram of the crack detection device 50. In Figure 3(c), the crack 3 is not shown.

As shown in FIG. 3(c), the crack detection device 50 includes a camera 51 that takes 360-degree images of the inner wall of the primary borehole 10 in the circumferential direction and generates an expanded image, a winch 52 that lifts the camera 51, and a microcomputer 53 that analyzes the expanded image generated by the camera 51. By using the winch 52 to move the camera 51 up and down in the primary borehole 10, an expanded image of the inner wall over the entire depth of the primary borehole 10 can be obtained. The microcomputer 53 performs image processing on the expanded image generated by the camera 51 to extract the crack 3 as a sine curve, and derives the amplitude, phase, and position of the sine curve as the run, inclination, and depth of the crack 3. The crack detection device 50 detects the run, inclination, and depth of the crack 3 for multiple primary boreholes 10.

As shown in FIG. 2, the crack detection device 50 inputs the strike, dip, and depth of the detected crack 3 to the controller 30. The strike, dip, and depth of the crack 3 detected using the crack detection device 50 may be input by an operator to the controller 30. The crack information acquisition unit 31 stores the input strike, dip, and depth of the crack 3. This completes the acquisition of the strike, dip, and depth of the crack 3 by the crack information acquisition unit 31.

Next, the evaluation of the continuity of the crack 3 by the evaluation unit 32 will be described with reference to Figures 2 and 4. The evaluation unit 32 evaluates the continuity of the crack 3 between adjacent primary boreholes 10 based on the strike, inclination, and depth of the crack 3 acquired by the crack information acquisition unit 31.

Figure 4(a) is a schematic diagram for explaining a method for evaluating the continuity of the crack 3 between the primary boreholes 11 and 12 illustrated in Figure 1(a) based on the strike, inclination, and depth of the crack 3. In Figure 4(a), the cracks 3b and 3c illustrated in Figure 1(a) are omitted. Here, the cracks 3a in the inner walls of the primary boreholes 11 and 12 are respectively referred to as the first and second cracks 3a1 and 3a2. In addition, the crack information acquisition unit 31 (see Figure 2) is assumed to have acquired the depths of the first and second cracks 3a1 and 3a2 as the first and second depths D1 and D2, respectively.

The crack 3a is considered to extend substantially planarly in the foundation ground 1. Therefore, when the first crack 3a1 and the second crack 3a2 are continuous, the strike and inclination of the first crack 3a1 and the strike and inclination of the second crack 3a2 are substantially the same. Also, when the first crack 3a1 and the second crack 3a2 are continuous, the depth D1' of the virtual crack 3a1' that appears on the inner wall of the primary borehole 12 when the first crack 3a1 is virtually extended as shown by the two-dot chain line in FIG. 4(a) is substantially the same as the second depth D2 of the second crack 3a2. The evaluation unit 32 evaluates the continuity of the first and second cracks 3a1 and 3a2 between the primary boreholes 11 and 12 by comparing the strike, inclination and depth D1' of the first crack 3a1 with the strike, inclination and depth D2 of the second crack 3a2.

Figure 4(b) is a flowchart showing the processing in the evaluation unit 32. As shown in Figure 4(b), in step S401, it is determined whether the difference between the strike of the first crack 3a1 and the strike of the second crack 3a2 is equal to or less than a predetermined first threshold. If the strike difference between the first crack 3a1 and the second crack 3a2 is equal to or less than the first threshold, the process proceeds to step S402, and if the strike difference between the first crack 3a1 and the second crack 3a2 exceeds the first threshold, the process proceeds to step S405.

In step S402, it is determined whether the difference between the inclination of the first crack 3a1 and the inclination of the second crack 3a2 is equal to or less than a predetermined second threshold. If the difference in inclination between the first crack 3a1 and the second crack 3a2 is equal to or less than the second threshold, the process proceeds to step S403. If the difference in inclination between the first crack 3a1 and the second crack 3a2 exceeds the second threshold, the process proceeds to step S405.

In step S403, it is determined whether the difference between the depth D1' of the virtual crack 3a1' that appears on the inner wall of the primary borehole 12 when the first crack 3a1 is virtually extended and the second depth D2 of the second crack 3a2 is equal to or less than a predetermined third threshold. If the depth difference between the virtual crack 3a1' and the second crack 3a2 is equal to or less than the third threshold, the process proceeds to step S404, and if the depth difference between the virtual crack 3a1' and the second crack 3a2 exceeds the third threshold, the process proceeds to step S405.

The process proceeds to step S404 when the strike, dip, and depths D1', D2 of the first crack 3a1 and the second crack 3a2 are all approximately the same. Therefore, in step S404, it is evaluated that the first crack 3a1 and the second crack 3a2 are continuous.

The process proceeds to step S405 if at least one of the strike, dip, and depth D1', D2 between the first crack 3a1 and the second crack 3a2 does not substantially match. Therefore, in step S405, it is evaluated that the first crack 3a1 and the second crack 3a2 are not continuous.

This completes the processing in the evaluation unit 32.

Next, the acquisition of the Lugeon value by the permeability information acquisition unit 33 will be described with reference to Figures 2 and 5. The Lugeon value acquired by the permeability information acquisition unit 33 is measured using a permeability measurement device 60 shown in Figure 5. Figure 5 is a schematic diagram of the permeability measurement device 60. In Figure 5, the cracks 3 are not shown. The measurement of the Lugeon value by the permeability measurement device 60 is performed before the grout material 2 is injected into the primary borehole 10.

As shown in FIG. 5, the permeability measuring device 60 includes a water injection pipe 61 that is formed so as to be insertable into the primary borehole 10, an upper packer 62 and a lower packer 63 that are spaced apart in the axial direction of the water injection pipe 61 on the outer periphery of the water injection pipe 61, an expansion/contraction section 64 that expands and contracts the upper packer 62 and the lower packer 63, a pump 65 that supplies water from a water tank 66 to the water injection pipe 61, and a microcomputer 67 that calculates the Lugeon value based on the water injection pressure and the water injection flow rate.

When the upper packer 62 and the lower packer 63 are expanded with the water injection pipe 61 inserted into the primary borehole 10, the upper packer 62 and the lower packer 63 define a test section L in the primary borehole 10. The test section L corresponds to the distance between the upper packer 62 and the lower packer 63.

The end of the water injection pipe 61 is closed, and a hole 61a is formed on the outer periphery of the water injection pipe 61 for injecting water into the test section L. The water injection pipe 61 is also provided with a pressure gauge 68 for measuring the water pressure in the test section L, and a flowmeter 69 for measuring the flow rate of water injected from the water injection pipe 61 into the test section L.

When the pump 65 is driven to inject water from the water injection pipe 61 into the test section L, the water injected into the test section L seeps into the foundation ground 1 from the inner wall of the primary borehole 10. When water is injected into the test section L so that the water pressure in the test section L is constant, the higher the permeability in the test section L, the greater the flow rate of water that seeps into the foundation ground 1, and the greater the flow rate injected into the test section L from the water injection pipe 61. The microcomputer 67 calculates the Lugeon value based on the water pressure measured by the pressure gauge 68 and the flow rate measured by the flowmeter 69.

The Lugeon values at multiple depths can be measured by moving the water injection pipe 61 up and down within the primary borehole 10 to change the depth of the test section L. Measurement of the Lugeon values at multiple depths using the permeability measuring device 60 is performed for multiple primary boreholes 10.

As shown in FIG. 2, the permeability measuring device 60 inputs the measured Lugeon value to the controller 30. The Lugeon value measured using the permeability measuring device 60 may be input to the controller 30 by an operator. The permeability information acquiring unit 33 stores the input Lugeon value. This completes the acquisition of the Lugeon value by the permeability information acquiring unit 33.

Next, the determination of whether or not additional injection of grout material 2 is required by the determination unit 34 will be described with reference to FIG. 6. Here, a case will be described in which it is determined whether or not additional injection of grout material 2 is required between the primary borehole 11 and the primary borehole 12 illustrated in FIG. 4(a). FIG. 6 is a flowchart showing the processing in the determination unit 34.

Additional injection of grout material 2 is necessary when the crack 3 is continuous between the primary boreholes 11, 12, it is difficult for the grout material 2 to reach the entire crack 3, and the crack 3 is a permeable crack. Therefore, the judgment unit 34 judges whether or not additional injection of grout material 2 is necessary based on the continuity of the crack 3 evaluated by the evaluation unit 32 and the Lugeon value acquired by the permeability information acquisition unit 33. Here, it is assumed that the permeability information acquisition unit 33 has acquired the Lugeon value in the primary borehole 11 at the first depth D1 and the Lugeon value in the primary borehole 12 at the second depth D2.

As shown in FIG. 6, in step S601, it is determined whether the first crack 3a1 and the second crack 3a2 are evaluated to be continuous. If the first and second cracks 3a1, 3a2 are evaluated to be continuous, the process proceeds to step S602, and if the first and second cracks 3a1, 3a2 are evaluated to be not continuous, the process proceeds to step S604.

In step S602, it is determined whether at least one of the Lugeon value of the primary borehole 11 at the first depth D1 and the Lugeon value of the primary borehole 12 at the second depth D2 is equal to or greater than a predetermined fourth threshold. The fourth threshold is a Lugeon value that is the boundary between whether the degree of permeability is acceptable or not. If at least one of the Lugeon values is equal to or greater than the fourth threshold, proceed to step S603, and if both Lugeon values are less than the fourth threshold, proceed to step S604.

The process proceeds to step S603 if the first and second cracks 3a1, 3a2 are continuous and permeable. Therefore, in step S603, it is determined that additional injection of grout material 2 between the primary boreholes 11, 12 is necessary.

The process proceeds to step S604 if the first and second cracks 3a1, 3a2 are not continuous, or if the first and second cracks 3a1, 3a2 are not permeable cracks. Therefore, in step S604, it is determined that there is no need to inject additional grout material 2 between the primary boreholes 11, 12.

This completes the processing in the judgment unit 34.

As shown in FIG. 2, the results of the processing in the judgment unit 34 are output and displayed on the display unit 40. FIG. 7 is an example of an image displayed on the display unit 40, showing the result of judging the need for additional injection of grout material 2 into the foundation ground 1 illustrated in FIG. 1 using the injection support device 100.

As shown in FIG. 7, the display unit 40 displays the primary borehole 10 with a solid line, and displays the secondary borehole 20 with a dashed line in the location where additional injection of grout material 2 is required (between primary boreholes 11 and 12 in the example shown in FIG. 7). This allows the worker to easily visually identify the location where additional injection of grout material 2 is required. Therefore, in the injection process, the secondary borehole 20 (see FIG. 1) can be formed in the location where additional injection of grout material 2 is required, and additional grout material 2 can be injected, allowing the grout material 2 to be appropriately injected into the foundation ground 1.

The display unit 40 also displays the continuity of the crack 3 evaluated by the evaluation unit 32 and the Lugeon value acquired by the permeability information acquisition unit 33. Specifically, to display the continuity of the cracks 3a and 3d, a disk 4a intersecting with the solid line indicating the primary boreholes 11 and 12 and a disk 4d intersecting with the solid line indicating the primary boreholes 13 and 14 are displayed. To display the continuity of the cracks 3b and 3c, a disk 4b intersecting only with the solid line indicating the primary borehole 11 and a disk 4c intersecting only with the solid line indicating the primary borehole 12 are displayed. To display the Lugeon value in the primary borehole 10, a circle 5 colored in a color corresponding to the Lugeon value and having a size is displayed on the solid line indicating the primary borehole 10. Therefore, by checking the display unit 40, the worker can grasp at a glance the continuity and Lugeon value of the crack 3 in addition to the location where additional injection of the grout material 2 is required.

In this manner, in this embodiment, the need to inject grout material 2 between adjacent primary boreholes 10 is determined based on the continuity of the crack 3 between adjacent primary boreholes 10 and the Lugeon value in the primary borehole 10. Therefore, if a crack 3 remains between adjacent primary boreholes 10 and is a permeable crack, the worker will form a secondary borehole 20 between the adjacent primary boreholes 10 and inject additional grout material 2 into the secondary borehole 20. Therefore, the grout material 2 can be appropriately injected into the foundation ground 1.

In the foundation ground 1 illustrated in FIG. 1, there are no continuous permeable cracks below the crack 3a between the primary boreholes 11 and 12. Therefore, when injecting additional grout material 2, it is sufficient to form a secondary borehole 20 up to the crack 3a.

In this embodiment, the depth of the crack 3a between the primary boreholes 11, 12 is estimated based on the depth of the crack 3a acquired by the crack information acquisition unit 31 (estimation process), and in the injection process, the secondary borehole 20 is formed to the depth estimated in the estimation process. Therefore, the secondary borehole 20 is formed to the depth required to reach the crack 3a. Therefore, the grout material 2 can be more appropriately injected into the foundation ground 1.

The estimation process is performed using the injection support device 100 shown in Figure 2. As shown in Figure 2, the controller 30 of the injection support device 100 further includes an estimation unit 35 that estimates the depth of the crack 3a between the primary boreholes 11 and 12 based on the first and second depths D1 and D2 (see Figure 4) acquired by the crack information acquisition unit 31 when the judgment unit 34 judges that the injection of the grout material 2 is necessary.

The estimation unit 35 assumes that the crack 3a extends in a plane between the primary boreholes 11, 12, and estimates the depth of the crack 3a between the primary boreholes 11, 12 by proportional allocation. Specifically, when estimating the depth Dc of the crack 3a at the center between the primary boreholes 11, 12 (see FIG. 4(a)), the following formula (1) is used.
Dc=(D2+D1)/2 (1)

The results of the processing by the estimation unit 35 are output to the display unit 40. As shown in FIG. 7, the display unit 40 displays a dashed line indicating the secondary borehole 20 with a length corresponding to the depth Dc estimated by the estimation unit 35. Therefore, the worker can easily visually confirm the length required for the secondary borehole 20 to reach the crack 3a. Therefore, the grout material 2 can be more appropriately injected into the foundation ground 1.

The above embodiment provides the following effects:

In this embodiment, the need to inject grout material 2 between adjacent primary boreholes 10 is determined based on the continuity of the crack 3 between adjacent primary boreholes 10 and the Lugeon value at the primary borehole 10. Therefore, if a crack 3 remains between adjacent primary boreholes 10 and is a permeable crack, additional grout material 2 is injected between adjacent primary boreholes 10. Therefore, the grout material 2 can be appropriately injected into the foundation ground 1.

In addition, in this embodiment, when it is determined that injection of grout material 2 is necessary between the primary boreholes 11, 12, the depth Dc of the crack 3 between the primary boreholes 11, 12 is estimated based on the first and second depths D1, D2 in the primary boreholes 11, 12, and the secondary borehole 20 is formed to the estimated depth Dc. Therefore, the secondary borehole 20 is formed to the depth required to reach the crack 3. Therefore, the grout material 2 can be more appropriately injected into the foundation ground 1.

Although the embodiments of the present invention have been described above, the above embodiments merely show some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

In the above embodiment, the permeability information acquisition unit 33 acquires the Lugeon values at the first and second depths D1 and D2, and the judgment unit 34 uses the Lugeon values at the first and second depths D1 and D2, but the present invention is not limited to this form. For example, in measuring the Lugeon values, the test section L may be set across the entire depth of the primary borehole 10, the Lugeon values at all depths in the primary borehole 10 may be measured, and the judgment unit 34 may use the Lugeon values at all depths.

When the judgment unit 34 judges whether or not additional injection of grout material 2 is required using the Lugeon values at the first and second depths D1 and D2 as in the above embodiment, it is possible to judge with higher accuracy whether or not the crack 3 is a permeable crack, and it is possible to more accurately judge whether or not additional injection of grout material 2 is required. Therefore, it is possible to more appropriately inject the grout material 2 into the foundation ground 1.

In the above embodiment, the evaluation unit 32 evaluates the continuity of the crack 3 using the strike, inclination, and depth of the crack 3, but the present invention is not limited to this form. The evaluation unit 32 may evaluate the continuity of the crack 3 based on, for example, the size of the gap in the crack 3, the color of the crack 3, etc.

In the above embodiment, the grout material 2 is injected into the primary borehole 10, but the primary borehole 10 may be an investigation hole into which the grout material 2 is not injected.

In the above embodiment, the display unit 40 displays the results of the processing by the determination unit 34 and the estimation unit 35, but as shown in FIG. 8, the display unit 40 does not have to display the results of the processing by the determination unit 34 and the estimation unit 35. The injection support device 101 for the grout material 2 according to a modified example of this embodiment will be described with reference to FIG. 8.

Figure 8(a) is a block diagram showing the configuration of the injection support device 101, and Figure 8(b) is an example of an image displayed on the display unit 40, showing the result of using the injection support device 101 on the foundation ground 1 illustrated in Figure 1. As shown in Figure 8(a), the injection support device 101 differs from the injection support device 100 in that the controller 130 does not include the judgment unit 34 and the estimation unit 35 shown in Figure 2. Also, as shown in Figure 8(b), the injection support device 101 differs from the injection support device 100 in that the display unit 40 does not display the secondary borehole 20 shown by the dashed line in Figure 7.

In the injection support device 101, the worker visually checks the continuity of the crack 3 and the Lugeon value displayed on the display unit 40 to determine whether or not grout material 2 needs to be injected between the primary boreholes 10. If it is determined that injection of grout material 2 is necessary, the depth of the crack 3 between the primary boreholes 10 is estimated, secondary boreholes 20 are formed between the primary boreholes 10 to the estimated depth, and grout material 2 is injected into the secondary boreholes 20. In other words, when using the injection support device 101, the worker makes the judgment using the judgment unit 34 and estimation unit 35 in the injection support device 100.

The injection support device 101 also allows the operator to simultaneously visually check the continuity of the cracks 3 and information regarding permeability, allowing the operator to appropriately determine whether or not to inject grout material 2 between the primary boreholes 10. Therefore, the grout material 2 can be appropriately injected into the foundation ground 1.

100, 101... injection support device 1... foundation ground 2... grout material 3, 3a, 3b, 3c, 3d... crack 3a1... first crack 3a2... second crack 10, 11, 12, 13, 14... primary borehole 31... crack information acquisition unit 32... evaluation unit 33... permeability information acquisition unit 34... judgment unit 40... display unit D1... first depth D2... second depth Dc... depth

Claims (3)

A method for injecting grout material into foundation ground, comprising:
a crack information acquisition process for acquiring information about cracks on inner walls of first and second primary boreholes formed at an interval in the foundation ground;
an evaluation process for evaluating the continuity of the crack between the first and second primary boreholes based on the information about the crack acquired in the crack information acquisition process;
A permeability information acquisition step of acquiring Lugeon values in the first and second primary boreholes;
A judgment process for judging whether or not it is necessary to inject the grout material between the first and second primary boreholes based on the continuity of the cracks evaluated in the evaluation process and the Lugeon value acquired in the permeability information acquisition process;
and an injection step of forming a secondary borehole between the first and second primary boreholes and injecting the grout material into the secondary borehole when it is determined in the determination step that injection of the grout material is necessary .
In the crack information acquisition step, at least the depths of the crack in the first and second primary boreholes are acquired as first and second depths, respectively;
In the permeability information acquisition step, the Lugeon value in the first primary borehole at the first depth and the Lugeon value in the second primary borehole at the second depth are acquired,
In the determination step,
When the cracks in the first and second primary boreholes are evaluated as being continuous in the evaluation process, and at least one of the Lugeon value in the first primary borehole at the first depth and the Lugeon value in the second primary borehole at the second depth is equal to or greater than a predetermined threshold, it is determined that injection of the grout material between the first and second primary boreholes is necessary;
If the evaluation step evaluates that the cracks in the first and second primary boreholes are not continuous, or if both the Lugeon value in the first primary borehole at the first depth and the Lugeon value in the second primary borehole at the second depth are less than the threshold value, it is determined that injection of the grout material between the first and second primary boreholes is unnecessary.
How to inject grout. When it is determined in the determination step that the injection of the grout material is necessary, the method further includes an estimation step of estimating the depth of the crack between the first and second primary boreholes based on the first and second depths acquired in the crack information acquisition step,
In the injection step, the secondary borehole is formed to the depth estimated in the estimation step.
A method for injecting grout material according to claim 1 . An injection support device that supports the injection of grout material into foundation ground,
a crack information acquisition unit that acquires information about cracks in inner walls of first and second primary boreholes formed at an interval in the foundation ground;
an evaluation unit that evaluates the continuity of the crack between the first and second primary boreholes based on information about the crack acquired by the crack information acquisition unit;
A permeability information acquisition unit that acquires Lugeon values in the first and second primary boreholes;
A judgment unit that judges whether or not it is necessary to inject the grout material between the first and second primary boreholes based on the continuity of the crack evaluated by the evaluation unit and the Lugeon value acquired by the water permeability information acquisition unit ,
The crack information acquisition unit acquires at least the depths of the crack in the first and second primary boreholes as first and second depths, respectively;
The permeability information acquisition unit acquires the Lugeon value in the first primary borehole at the first depth and the Lugeon value in the second primary borehole at the second depth,
The determination unit is
When the evaluation unit evaluates that the cracks in the first and second primary boreholes are continuous, and at least one of the Lugeon value in the first primary borehole at the first depth and the Lugeon value in the second primary borehole at the second depth is equal to or greater than a predetermined threshold, it is determined that injection of the grout material between the first and second primary boreholes is necessary;
When the evaluation unit evaluates that the cracks in the first and second primary boreholes are not continuous, or when both the Lugeon value in the first primary borehole at the first depth and the Lugeon value in the second primary borehole at the second depth are less than the threshold value, it is determined that injection of the grout material between the first and second primary boreholes is unnecessary.
A device to assist in the injection of grout materials.