Method for suppressing shear slippage at fault

Abstract

This earthquake suppression method involves injecting a shear thickening fluid into a crack that has been formed in underground bedrock. The shear thickening fluid contains a dispersion medium and a filler. Silica nanoparticles or cornstarch can be used as the filler.

Description

Methods for suppressing shear slip on faults

[0001] This application claims priority to Japanese Patent Application No. 2024-147766, filed on August 29, 2024, the contents of which are incorporated herein by reference.

[0002] In the development of underground resources for energy resources such as oil, shale gas, and geothermal energy, or mineral resources such as gold, platinum, and diamonds, the depths at which development is carried out are increasing year by year, and in recent years, development has been carried out at depths of up to 5 km underground.

[0003] For example, in the development of shale gas, a method is adopted in which a well is drilled vertically, then drilled horizontally, and then a fracturing fluid is injected into the drilled well at high pressure to hydraulically fracture the rock mass (see Patent Documents 1 and 2).

[0004] Japanese Patent Publication No. 2018-43221 Japanese Patent No. 2957293

[0005] However, as underground development depth increases, the force of the rock mass acting on existing fractures and faults underground increases, reducing the friction between the fractures and faults, which can lead to induced earthquakes. In shale gas development, induced earthquakes occur due to hydraulic fracturing, and in areas where shale gas is developed, there has been an increase in earthquakes that are thought to be induced earthquakes in recent years, calling for measures to prevent induced earthquakes.

[0006] The present invention has been proposed in view of the above-mentioned problems, and aims to provide a method for suppressing shear slip on faults up to about 5 km underground, which is caused by underground resource development.

[0007] In order to solve the above problems, the present invention proposes the following means for suppressing shear slip of a fault: (1) The present invention is characterized by injecting a shear-thickening fluid into a crack formed in an underground bedrock.

[0008] In the method of suppressing fault shear slip of the present invention, a shear-thickening fluid is injected into cracks formed in underground bedrock, and it is expected that the shear slip that induces earthquakes will be suppressed.

[0009] (2) In the method for suppressing shear slip of a fault described in (1), it is preferable to inject the shear-thickening fluid every 4 to 7 days.

[0010] In the method of suppressing shear slip on a fault of the present invention, the shear-thickening fluid is injected every 4 to 7 days, which is expected to maintain the shear-thickening properties of the shear-thickening fluid filled in the cracks and suppress shear slip that induces earthquakes.

[0011] (3) In the method for suppressing shear slip of a fault according to (1) or (2), the shear thickening fluid is SiO ２ It is preferred to use a composition comprising nanowires.

[0012] In the method for suppressing shear slip of a fault according to the present invention, the shear thickening fluid is SiO ２ The use of nanowire-containing materials is expected to enhance shear thickening properties and suppress shear slip that triggers earthquakes.

[0013] (4) In the method for suppressing shear slip of a fault described in any one of (1) to (3), it is preferable that the filling rate of the crack portion with the injected shear-thickening fluid is 90 volume % or more and 100 volume % or less.

[0014] In the method of the present invention for suppressing shear slip on a fault, the filling rate of the crack portion with the injected shear-thickening fluid is 90 volume % or more and 100 volume % or less, so it is expected that shear slip that induces earthquakes will be suppressed.

[0015] (5) In the method for suppressing shear slip of a fault described in any one of (1) to (4), it is preferable to inject the shear-thickening fluid through a crack that connects the ground to the crack portion or through a communication hole formed to connect the ground to the crack portion.

[0016] In the method for suppressing shear slip of a fault of the present invention, the shear-thickening fluid is injected through a crack that connects the ground to the crack portion, or through a communication hole that is formed to connect the ground to the crack portion.Therefore, boreholes that are constructed during underground resource development can be used directly to inject the shear-thickening fluid, which is expected to reduce the costs of suppressing shear slip that induces earthquakes.

[0017] (6) In the method for suppressing shear slip of a fault described in any one of (1) to (5), it is preferable to inject the shear-thickening fluid into the crack formed directly below a mine or an artificial structure.

[0018] In the method for suppressing shear slip on a fault of the present invention, the shear-thickening fluid is injected into the crack formed directly below a mine or artificial structure, and it is expected that shear slip that induces earthquakes occurring directly below the mine or artificial structure will be suppressed.

[0019] According to the present invention, it is possible to provide a method for suppressing shear slip on faults up to about 5 km underground, which is caused by underground resource development.

[0020] 1 is a schematic cross-sectional view of an underground fracture showing the process of injecting a shear-thickening fluid of the present embodiment into the underground fracture. FIG. 2 is a schematic cross-sectional view of an underground fracture showing the occurrence of shear slip in the underground fracture into which the shear-thickening fluid of the present embodiment has been introduced. FIG. 3 is a perspective view of a low-speed rotation friction tester used to test the behavior of the shear-thickening fluid of the present embodiment. FIG. 4 is a side view of a test section within the low-speed rotation friction tester used to test the behavior of the shear-thickening fluid of the present embodiment. FIG. 5 is a top view of a Teflon ring within the low-speed rotation friction tester used to test the behavior of the shear-thickening fluid of the present embodiment. FIG. 6 is a top view of a Teflon ring provided on a lower holder and a top view of an upper holder within the low-speed rotation friction tester used to test the behavior of the shear-thickening fluid of the present embodiment. FIG. 7 is a side view of a test section within the low-speed rotation friction tester including a shear-thickening fluid-applied surface after testing the behavior of the shear-thickening fluid of the present embodiment. 1 is a graph showing the relationship between the displacement of the load point and the displacement of the velocity and friction coefficient based on the theoretical law of velocity-state dependence of friction shown in Equation (1). FIG. 2 is a graph showing the relationship between the displacement of the load point and the displacement of the velocity and friction coefficient for the shear-thickening fluid of Example 1, with the velocity step changed. FIG. 3 is a graph showing the relationship between the velocity displacement of the load point and (a-b) for the shear-thickening fluid of Example 1. FIG. 4 is a graph showing the relationship between the velocity displacement of the load point and D for the shear-thickening fluid of Example 1. ｃ 1 is a graph showing the relationship between the velocity displacement of the load point and k (μm) for the shear thickening fluid of Example 1. ｃ 1 is a graph showing the relationship between the velocity displacement of the load point and (a-b), D (GPa / μm) in the test of Comparative Example 1 in which no shear-thickening fluid was used. ｃ 1 is a graph showing the relationship between shear displacement (μm) and friction coefficient (μm). 2 is a graph comparing the shear displacement dependence of friction coefficient between a test using the shear thickening fluid of Example 1 and a test not using the shear thickening fluid of Comparative Example 1. 3 is a graph comparing the behavior of the test using the shear thickening fluid of Example 1 and the behavior of the test not using the shear thickening fluid of Comparative Example 1 when a stick-slip test is performed.

[0021] Hereinafter, a shear slip suppression method according to one embodiment of the present invention will be described with reference to the drawings. Note that the embodiment shown below is specifically described to provide a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified. Furthermore, the drawings used in the following description may show essential parts enlarged for convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as those in reality.

[0022] (Shear-Thickening Fluid) In the method for suppressing shear slip of a fault according to this embodiment, a shear-thickening fluid (STF) is injected into a crack formed in an underground rock mass. A shear-thickening fluid is a fluid that exhibits shear thickening (dilatancy) properties, and its viscosity increases in response to an increase in shear rate. More specifically, a shear-thickening fluid behaves like a liquid when the shear stimulus acting on the fluid is slow and small, but solidifies and exerts solid-like resistance when the shear stimulus acting on the fluid is fast and large. Furthermore, a shear-thickening fluid has the property of returning to its original low-viscosity state when the external force acting on the fluid is removed.

[0023] The shear-thickening fluid of this embodiment may be a shear-thickening fluid composition containing a dispersion medium and a filler. The shear-thickening fluid composition may optionally contain a dispersant.

[0024] The dispersion medium may be one or more selected from water, oil, and alcohols. However, from the viewpoint of environmental protection in underground resource development, water is preferred. Ethylene glycol may also be used as the dispersion medium. The dispersion medium is preferably contained in the shear-thickening fluid composition in a range of 40% by mass to 80% by mass, more preferably 50% by mass to 75% by mass.

[0025] The filler (solid component) can be one selected from inorganic fine particles and organic fine particles. Examples of inorganic fine particles include silica nanoparticles, and examples of organic fine particles include cornstarch. As the silica nanoparticles, silica nanoparticles with an average particle size of about 12 nm can be used. Here, the average particle size is the number average particle size. As the cornstarch, commercially available cornstarch can be used.

[0026] The filler is preferably contained in the shear-thickening fluid composition in an amount of from 20% to 60% by mass, more preferably from 25% to 50% by mass. When the filler content in the shear-thickening fluid composition is from 20% to 60% by mass, the viscosity of the shear-thickening fluid composition increases when the shear rate is from 1 μm / s to 100 μm / s, and the shear-thickening fluid composition exhibits solid-like resistance, which is expected to suppress shear slip of faults up to about 5 km underground.

[0027] When the filler is silica nanoparticles, the filler contains SiO ２ Nanowires can also be used in combination. ２ The nanowires are made of SiO2 having an outer diameter of 1.0 nm to 2.0 μm and a length of 1.0 μm to 100 μm. ２ Nanowires can be used. SiO ２ When nanowires are mixed, SiO in the shear-thickening fluid composition ２ The nanowire content is preferably 0.625 mass % or more and 1.250 mass % or less. ２ The inclusion of nanowires can improve viscosity at shear rates of 1 μm / sec or more and 100 μm / sec or less.

[0028] The shear-thickening fluid composition can be obtained by adding a filler to a dispersion medium and mixing the mixture uniformly using a mixer or the like.

[0029] (Method for suppressing shear slip of a fault) A shear-thickening fluid composed of a shear-thickening fluid composition can be introduced into a crack formed in an underground rock mass by a conventional method. That is, the shear-thickening fluid is preferably injected through a crack that connects the ground to the crack, or through a communication hole formed to connect the ground to the crack. Specifically, methods that can be considered include injecting the shear-thickening fluid directly into a well bore created for drilling shale gas or the like, thereby introducing the shear-thickening fluid into the crack that connects to the well bore, or using equipment that is used to inject a fracturing fluid to hydraulically fracture rock to form a well bore. Alternatively, the shear-thickening fluid may be filled into the crack each time the rock mass is fractured.

[0030] Examples of fractures into which shear-thickening fluids can be introduced include fractures formed beneath mines or artificial structures, such as facilities for drilling for energy resources such as shale gas.

[0031] When introducing the shear-thickening fluid into the crack, it is desirable to check the volume of the crack in advance. The volume of the crack is not particularly limited, but is preferably 0.10 m ３ More than 5000m ３ Preferably, the volume is 0.10 m or less. ３ More than 5000m ３ It is expected that filling cracks with shear-thickening fluid will suppress the shear slip that triggers earthquakes.

[0032] The volume of a crack can be determined by acoustic or elastic wave detection. Examples of methods that can be used for detecting an elastic wave include refraction detection, reflection detection, surface wave detection, and elastic wave tomography. Specifically, refracted waves or reflected waves generated by an excitation device such as gunpowder or a hammer, or surface waves generated by an excitation device, are acquired by multiple receivers, recorded by a measuring device, and analyzed to calculate the volume of the crack.

[0033] Furthermore, if the well penetrates a fault, the opening of the fault can be predicted from the penetrated portion using the scaling law, and the volume of the crack can be calculated. Here, the scaling law is an empirical law that shows the relationship between the magnitude of the induced earthquake, the length of the fault, the width of the fault displacement, and the fault area.

[0034] When introducing the shear-thickening fluid into the crack, the filling rate of the crack with the shear-thickening fluid is preferably 90% by volume or more and 100% by volume or less, and more preferably 95% by volume or more and 100% by volume or less. If the filling rate of the shear-thickening fluid in the crack is 90% by volume or more and 100% by volume or less, it is expected that shear slip that induces earthquakes will be suppressed.

[0035] The cracks into which shear-thickening fluids are introduced are usually cracks in the rock mass, and the filled shear-thickening fluid tends to remain within the cracks. Therefore, it is preferable to inject shear-thickening fluids every 4 to 7 days. Injecting shear-thickening fluids every 4 to 7 days is expected to maintain the shear-thickening properties of the shear-thickening fluid and suppress shear slip that induces earthquakes.

[0036] The method of injecting the shear-thickening fluid into underground fractures according to this embodiment and the mechanism by which the shear-thickening fluid suppresses shear slip that induces earthquakes will be described with reference to FIGS. 1A and 1B.

[0037] First, as shown in Figure 1A, in a rock mass 10 having an underground crack 12, shear stress S and normal stress N are generated in the rock mass 10 across the crack 12. By injecting a shear-thickening fluid 11 into this crack 12, pore water pressure P is generated in the rock mass 10.

[0038] The shear-thickening fluid 11 of this embodiment has fluidity and the ability to move over a wide range as long as the shear rate of shear sliding does not increase. On the other hand, when the shear rate of shear sliding accelerates and shear sliding occurs, shear stress S is applied to the shear-thickening fluid 11 filled in the cracks 12 of the rock mass 10. The shear-thickening fluid 11 of this embodiment has the property that, when the shear stimulus acting on the fluid is rapid and large, it solidifies and exhibits solid-like resistance. In particular, if shear sliding occurs in a rock mass 10 where underground resource development is being carried out up to approximately 5 km underground, it is expected that the shear-thickening fluid 11 in the cracks 12 will thicken and almost solidify.

[0039] In this way, when the shear-thickening fluid 11 in the crack 12 thickens and becomes almost solidified, the energy of shear slip is consumed in the destruction of the shear-thickening fluid 11, and it is thought that shear slip of the fault is suppressed.

[0040] As described above, according to the method for suppressing shear slip of a fault using a shear-thickening fluid of this embodiment, it is expected that the shear slip of the fault will be suppressed by the solidification action of the shear-thickening fluid.

[0041] Although one embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as the inventions described in the claims and their equivalents.

[0042] Using the low-speed rotation friction tester 20 shown in FIG. 2A, a shear slip test was conducted in the laboratory to test the effectiveness of the method of suppressing shear slip of a fault according to the present invention.

[0043] The low-speed rotation friction tester 20 used in the examples includes an axial load sensor 21, a bearing 22, a torque load sensor 23, a test section 30, a rotating disk 24, and a rotation position sensor 25. As shown in FIG. 2B , the test section 30 includes an upper fixed block 31, a lower fixed block 33, and a Teflon (registered trademark) ring 32 disposed between the upper fixed block 31 and the lower fixed block 33.

[0044] An upper holder 35 is fixed to the upper fixed block 31, and a lower holder 34 is fixed to the lower fixed block 33. As shown in Figures 2C and 3, the upper holder 35 is provided with a ring-shaped test specimen holder 35a with an uneven surface, and the lower holder 34 is provided with a Teflon ring 32 and a ring-shaped test specimen holder 34a with an uneven surface. The Teflon ring 32 is composed of a disk-shaped first Teflon ring 32a located in the center and a ring-shaped second Teflon ring 32b located on the outer periphery of the first Teflon ring 32a, and the test specimen holder 34a is located between the first Teflon ring 32a and the second Teflon ring 32b.

[0045] Example 1: 75% by mass of ethylene glycol and 25% by mass of silica nanoparticles (AEROSIL, manufactured by EVONIK, average particle size 12 nm) were uniformly mixed in a mixer to obtain a shear-thickening fluid. The resulting shear-thickening fluid was applied to the upper holder 35 and the lower holder 34 until the grooves on the surface of the specimen holder 35a were completely covered. A rock gouge (powder) (quartz powder, average particle size 106 μm / s) was then placed on the shear-thickening fluid-applied surface as a simulated rock substrate. The vertical pressure was increased to 5 MPa to compress the rock gouge, and the pressure was maintained for approximately one hour to uniformly compress the grooves on the specimen holders 34a and 35a. A low-speed rotational friction test was then conducted under the following conditions, and a speed-step test was performed while measuring the friction response (torque).

[0046] In Example 1, the speed step test was performed under the following conditions: Indoor humidity: approximately 43% Indoor temperature: 23°C Normal stress: 5 MPa Load point speed: Initially set to 10 μm / s, followed by four cycles of varying the rotational friction speed in the order of 0.3 μm / s, 1 μm / s, 3 μm / s, 10 μm / s, 30 μm / s, and 100 μm / s Load point displacement: Initially set to 10 mm, followed by four cycles of varying the sliding distance in the order of 0.36 mm, 0.5 mm, 0.51 mm, 0.5 mm, 0.6 mm, and 1.5 mm.

[0047] In the speed step test of Example 1, the relationship between the displacement of the load point and the displacement of the speed / friction coefficient shown in FIG. 6 was obtained.

[0048] Comparative Example 1 In Comparative Example 1, a velocity step test was carried out in the same manner as in Example 1, but without using a shear-thickening fluid.

[0049] (Evaluation) The theoretical law of speed- and state-dependence of friction indicates the behavior of friction expressed by the following general formula (1).

[0050]

[0051] Equation (1) shows that the shear stress τ depends on the normal stress σn, the slip ratio V, and the state variable θ. ０ is the reference friction coefficient (when the sliding speed is V ０ where a is the direct effect of friction, b is the enhanced effect of friction, and D is the steady-state friction coefficient when ｃ is the distance (critical sliding distance) required for the friction coefficient to decrease to the kinetic friction coefficient, and θ is the average lifespan of particle contact.

[0052] The relationship between the displacement of the load point and the displacement of the speed / friction coefficient, based on the theoretical law of the speed / state dependency of friction when the speed step change, i.e., when the additional point speed of low speed rotation is changed, obtained by Equation (1), is shown in Figure 5. The curve of the experimental data shown in Figure 6 obtained in Example 1 is fitted to the theoretical law shown in Figure 5, and the parameters a, b, D ｃ In Comparative Example 1, the parameters a, b, and D were calculated in the same manner. ｃ was calculated.

[0053] The parameters a, b, and D obtained in Example 1 ｃ The relationship between the speed displacement of the load point and (a-b) is shown in FIG. 7. ｃ The relationship between the speed displacement of the load point and K ｃ The relationship between the K and the tensile strength (GPa / μm) is shown in FIG. ｃ (GPa / μm) is the parameter a, b, D ｃ and is calculated by the following general formula (2).

[0054] K ｃ (GPa / μm)=(σ n (b-a) / Dc) (2) In equation (2), σ n indicates the normal stress during the experiment.

[0055] Parameters a, b, and D obtained in Comparative Example 1 ｃ Using the speed displacement of the load point, (a-b), and D ｃ The relationship between these values ​​is shown in FIG.

[0056] Regarding the obtained parameters a and b, if (a - b) > 0, the shear slip is stabilized and earthquakes are unlikely to occur, whereas if (a - b) < 0, the shear slip becomes unstable and there is a possibility that the shear slip may develop into an earthquake. Faults are constantly moving, but if the shear slip velocity is slow, or if the shear slip stops while sliding slowly, earthquakes tend not to occur. On the other hand, if shear slip occurs suddenly with a large force, there is a concern that the shear slip may develop into an earthquake. In this example, the state of shear slip was measured using (a - b), calculated from the parameters a and b.

[0057] 7 shows that (a-b) increases with each change in velocity step, i.e., with each increase in the load-point velocity, and satisfies (a-b) > 0 when the load-point velocity is 100 μm / s. Therefore, with the shear-thickening fluid of Example 1, the viscosity of the shear-thickening fluid composition increases when the shear rate is 100 μm / s, and it is expected to exert solid-like resistance and suppress shear slip of the fault.

[0058] According to FIG. 8, the distance D required for the friction coefficient to decrease to the dynamic friction coefficient is ｃ It is shown that the shear shear rate (μm) tends to increase with each change in velocity step, i.e., with an increase in the load point velocity. In other words, the distance required for the shear shear rate to accelerate increases with increasing velocity, suggesting that even if the shear shear rate accelerates, the acceleration is not sudden but gradual. Therefore, from the results of Figure 8, it can be seen that the shear thickening fluid of Example 1 does not cause a sudden increase in shear rate, and is expected to have the effect of suppressing shear slip of the fault. Furthermore, when shear slip changes into an earthquake, when the velocity step is changed, D ｃ (μm) shows a nearly constant value.

[0059] According to FIG. 9, the critical stiffness K ｃ It is shown that the critical stiffness K (GPa / μm) tends to decrease with each speed step change, i.e., with each increase in the load point speed. ｃ (GPa / μm) shows a tendency to decrease when the velocity step is changed. In this case, from equation (2) that defines the parameter Kc (GPa / μm), the shear thickening fluid of Example 1 is expected to have the effect of suppressing shear slip of the fault without causing a sudden increase in shear rate. In addition, when shear slip changes into an earthquake, when the velocity step is changed, K ｃ (GPa / μm) shows an almost constant value.

[0060] 10 shows that (a-b) remains almost constant even when the velocity step is changed, i.e., when the load point velocity is increased, (a-b) < 0. Therefore, it was shown that when the shear thickening fluid of Comparative Example 1 is not used, the effect of suppressing shear slip of the fault cannot be expected.

[0061] According to FIG. 10, the distance D required for the friction coefficient to decrease to the dynamic friction coefficient is ｃThe shear slip (μm) remained almost constant even when the velocity step was changed, i.e., the load point velocity was increased. In other words, the distance required for the shear rate to accelerate did not increase as the velocity increased, which raised concerns that the acceleration of the shear rate would become too rapid and that shear slip could turn into an earthquake. In other words, it was shown that if the shear thickening fluid of Comparative Example 1 is not used, the effect of suppressing shear slip on the fault cannot be expected.

[0062] FIG. 11 compares the shear displacement dependence of the friction coefficient (μ) between the test using the shear-thickening fluid (STF) of Example 1 and the test (pure gouge) without the shear-thickening fluid of Comparative Example 1. As shown in the graph of FIG. 11, at the start of the shear-sliding test, the friction coefficient under the condition with the shear-thickening fluid (STF) of Example 1 is lower than the friction coefficient under the test (pure gouge) without the shear-thickening fluid of Comparative Example 1. This indicates that the shear-thickening fluid functions like a lubricant. On the other hand, as the shear-sliding test continues, the friction coefficient under the condition with the shear-thickening fluid (STF) of Example 1 becomes higher than the friction coefficient under the test (pure gouge) without the shear-thickening fluid of Comparative Example 1, confirming that the shear-thickening fluid exerts solid-like resistance under the conditions using the shear-thickening fluid of Example 1.

[0063] Figure 12 compares the results of stick-slip tests conducted using the shear-thickening fluid (STF) of Example 1 and the test (pure gouge) of Comparative Example 1 without the shear-thickening fluid. A stick-slip test involves continuously increasing displacement to intermittently excite stick-slip. Acoustic emission (AE) waves measured in the stick-slip test are emitted when stick-slip occurs, and AEs are counted. As shown in Figure 12, in the test using the shear-thickening fluid (STF) of Example 1, no AE waves were generated and no AEs were counted. However, in the test (pure gouge) without the shear-thickening fluid of Comparative Example 1, stick-slip occurred, and AE waves were generated and AEs were counted. This test demonstrated that the test using the shear-thickening fluid (STF) of Example 1 is expected to be effective in suppressing shear slip on faults.

[0064] The earthquake suppression method of the present invention is expected to suppress shear slip of faults up to about 5 km underground, which is caused by underground resource development. This method can be applied to underground resource development for energy resources such as oil, shale gas, and geothermal energy, or mineral resources such as gold, platinum, and diamonds.

[0065] 10 Rock mass 11 Shear thickening fluid 12 Crack S Shear stress N Normal stress P Pore water pressure 20 Low speed rotation friction testing machine

Claims

1. A method for suppressing earthquakes, characterized by injecting shear-thickening fluid into cracks formed in underground bedrock.

2. The earthquake suppression method according to claim 1, characterized in that the injection of the shear-thickening fluid is carried out every 4 to 7 days.

3. The shear thickening fluid is SiO ２ 3. The method for suppressing earthquakes according to claim 1, wherein a composition containing nanowires is used.

4. A method for suppressing earthquakes as described in either claim 1 or 2, characterized in that the filling rate of the cracked portion with the injected shear-thickening fluid is 90 volume % or more and 100 volume % or less.

5. A method for suppressing earthquakes as described in either 1 or 2, characterized in that the shear-thickening fluid is injected through a crack that connects the ground to the crack portion, or through a communication hole formed to connect the crack portion.

6. A method for suppressing earthquakes as described in either claim 1 or claim 2, characterized in that the shear-thickening fluid is injected into the crack formed directly beneath a mine or an artificial structure.

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