Explosion particles, preparation method and repair method for repairing rock mass cracks by using water pressure

Abstract

The present invention discloses an explosive granule, a preparation method and a repair method for repairing rock mass cracks by using water pressure, which relates to the technical field of rock mass crack repair. The explosive granule comprises a shear-resistant gel film and a water-soluble film wrapped outside the shear-resistant gel film. The shear-resistant gel film is a calcium alginate gel film, and the water-soluble film is a polyvinyl alcohol film. Urea is wrapped inside the shear-resistant gel film, and nutrients and microorganisms with urease present in the body are provided between the shear-resistant gel film and the water-soluble film. When the external water pressure is greater than the shear strength of the shear-resistant gel film, the shear-resistant gel film ruptures to release the urea therein. The explosive granule, the preparation method and the repair method for repairing rock mass cracks by using water pressure provided by the present invention enable the calcification reaction to start from deep cracks and repair the cracks from deep to shallow, ensuring the crack repair effect.

Description

Technical Field

[0001] The present invention relates to the technical field of rock mass crack repair, and particularly to an explosive granule for repairing rock mass cracks by using water pressure. Background Art

[0002] In view of the "storing clear water and discharging turbid water" operation mode adopted by the Three Gorges Project, that is, the operation water level is 145 m in winter (dry season) and 175 m in summer (flood season), this will form a drawdown zone with a maximum water level drop of 30 m along the river in the reservoir area.

[0003] Due to the rise and fall of the water level in the basin and the complex geological conditions, the rock mass on both sides of the drawdown zone cracks and deteriorates, greatly reducing the mechanical and durability properties of the rock mass. Under the long-term erosion and seepage effects, serious water and soil separation occurs in the rock mass of the drawdown zone, exacerbating the risk of natural disasters. If not repaired in time, serious safety accidents may occur. Therefore, in order to maintain the coastal ecological environment, it is necessary to repair the rock mass cracks in time.

[0004] Traditional crack repairs generally use polymer ultra-fine cement, epoxy resin materials, polymer grouting materials, etc., which have disadvantages such as poor compatibility, high cost, and large pollution during use. For the Yangtze River Basin, such slurries will cause certain pollution to the water body. Therefore, it is urgent to develop a new type of green repair method. Microbial Induced Carbonate Precipitation (MICP) is an eco-friendly energy-saving technology with advantages such as low energy consumption, various types, and environmental friendliness, and has been widely used in the crack repair of geotechnical engineering. The products of microbial mineralization are mainly calcium carbonate, which has good stability and durability, good compatibility with the matrix material, and no pollution to the environment. Its mechanism of action is to add urea, calcium source, and nutrients to the microbial solution, and rely on the self-metabolism of microorganisms. Urease catalyzes the hydrolysis of urea to produce CO3 2- and NH4 + , and in an alkaline environment, CO3 2- can combine with the surrounding Ca 2+ to form CaCO3 crystal precipitation. However, since the existing technology injects microorganisms, urea, and calcium source successively for microbial-induced calcification, it will cause part of the calcification reaction to occur in the shallow cracks, and the generated crystals will hinder the subsequent added substances, resulting in poor crack repair effect in the deep part of the cracks and more difficult to control the repair effect in the natural environment. Summary of the Invention

[0005] The object of the present invention is to provide an explosive granule for repairing rock mass cracks by using water pressure, a preparation method and a repair method, so as to solve the problems existing in the above-mentioned prior art, and make the calcification reaction start from deep cracks by using water pressure, and repair the cracks from deep to shallow to ensure the crack repair effect.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides an explosive granule for repairing rock mass cracks by using water pressure, which includes a shear-resistant gel film and a water-soluble film wrapped outside the shear-resistant gel film. The shear-resistant gel film is a calcium alginate gel film, and the water-soluble film is a polyvinyl alcohol film; urea is wrapped inside the shear-resistant gel film, and nutrients and microorganisms with urease present in the body are provided between the shear-resistant gel film and the water-soluble film. When the external water pressure is greater than the shear strength of the shear-resistant gel film, the shear-resistant gel film ruptures to release the urea therein.

[0008] Preferably, the microorganisms include Bacillus sphaericus and Sarcina pasteurii.

[0009] Preferably, the nutrients include yeast extract.

[0010] The present invention also provides a preparation method of the above-mentioned explosive granule for repairing rock mass cracks by using water pressure, including the following steps:

[0011] (1) Take urea and add it to an aqueous sodium alginate solution, stir evenly, drop the obtained suspension into an aqueous calcium chloride solution, stir and then filter, wash with water to obtain a hydrogel, and naturally dry it at room temperature to obtain a calcium alginate dry gel wrapped with urea.

[0012] (2) Add the calcium alginate dry gel wrapped with urea and spore powder to yeast extract. The spore powder is the spore-state powder of microorganisms with urease present in the body. After degassing and mixing, inject it into a chamber composed of two glass plates, and the two glass plates are separated by a silica gel gasket; inject an aqueous polyvinyl alcohol solution to completely cover the mixed solution, then clamp the glass plates and perform ultraviolet irradiation to obtain an explosive granule for repairing rock mass cracks by using water pressure.

[0013] Preferably, the preparation method of the spore powder includes the following steps:

[0014] Sterilize the MBS medium, transfer mature spores as inoculum to the MBS medium, incubate the culture, harvest the spores by centrifuging the culture, remove the supernatant, vacuum-dry the spore paste at room temperature to obtain a dry paste of spores, and then grind the dry paste of spores to obtain spore powder for encapsulation.

[0015] The present invention also provides a method for repairing rock mass cracks, which uses the explosive particles for repairing rock mass cracks by utilizing water pressure as described above, and includes the following steps:

[0016] (1) Spraying water with explosive particles onto the rock wall, and the explosive particles flow into the cracks along with the water;

[0017] (2) As the explosive particles become saturated in the cracks, the outer water-soluble film gradually ruptures over time, releasing the microorganisms therein. The microorganisms combine with the calcium source in the crack wall and attach to the crack wall;

[0018] (3) As the water level rises, water flows into the cracks, the water pressure in the cracks gradually increases, and the shear-resistant gel films of the explosive particles in the cracks rupture successively from deep to shallow under the action of water pressure, releasing the internal urea. The urea produces carbonate ions under the action of microbial urease, and the carbonate ions react chemically with the calcium source on the crack wall to form calcium carbonate crystals, which attach to the crack wall, and the cracks are repaired from deep to shallow.

[0019] The present invention has achieved the following technical effects compared with the prior art:

[0020] For the explosive particles, preparation method and repair method for repairing rock mass cracks by utilizing water pressure provided by the present invention, after the explosive particles flow into the cracks along with the water, the outer water-soluble film gradually ruptures over time, releasing the microorganisms therein. The microorganisms combine with the calcium source in the crack wall and attach to the crack wall. As the water level rises, water flows into the cracks, the water pressure in the cracks gradually increases, and the shear-resistant gel films of the explosive particles in the cracks rupture successively from deep to shallow under the action of water pressure, releasing the internal urea. The urea produces carbonate ions under the action of microbial urease, and the carbonate ions react chemically with the calcium source on the crack wall to form calcium carbonate crystals, which attach to the crack wall, and the cracks are repaired from deep to shallow, ensuring the crack repair effect. The present invention is applicable to the repair of rock mass cracks in the water-level-fluctuation zone on both sides of the Yangtze River. It can utilize the characteristics of the water-level change in the water-level-fluctuation zone of the Yangtze River. When the water level is low, the repair material is sprayed, and as the water level rises, the pressure is used to rupture the explosive particles, and the released substances produce a solidification effect, which can ensure the effective repair of the deep part of the cracks, that is, the effect of "repairing rocks with water". BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1Schematic structural diagram of the explosive particles for repairing rock mass cracks provided by the present invention;

[0023] Figure 2 Schematic diagram of repairing cracks with explosive particles in the present invention;

[0024] Figure 3 SEM image of the interior of a sample crack without microbial treatment in the governance effect measurement test of the present invention;

[0025] Figure 4 SEM image of the interior of a sample crack after microbial treatment in the governance effect measurement test of the present invention;

[0026] In the figure: 1 - shear-resistant gel film, 2 - water-soluble film, 3 - urea, 4 - nutrient, 5 - microorganism, 6 - crack, 7 - crack wall, 8 - calcium carbonate crystal. Detailed implementation manners

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] The purpose of the present invention is to provide an explosive particle, a preparation method and a repair method for repairing rock mass cracks using water pressure, so as to solve the problems existing in the prior art. By using water pressure, the calcification reaction can start from deep cracks and repair the cracks from deep to shallow to ensure the crack repair effect.

[0029] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0030] As Figure 1 - Figure 2 shown, this embodiment provides an explosive particle for repairing rock mass cracks using water pressure, which includes a shear-resistant gel film 1 and a water-soluble film 2 wrapped outside the shear-resistant gel film 1. The shear-resistant gel film 1 is an alginate calcium gel film, and the water-soluble film 2 is a polyvinyl alcohol film; urea 3 is wrapped inside the shear-resistant gel film 1, and a nutrient 4 and a microorganism 5 with urease in vivo are provided between the shear-resistant gel film 1 and the water-soluble film 2. When the external water pressure is greater than the shear strength of the shear-resistant gel film 1, the shear-resistant gel film 1 ruptures to release the urea 3 therein.

[0031] Among them, the shear-resistant gel film 1 is an alginate calcium gel film, and the shear strength of the shear-resistant gel film 1 should be such that it will not be damaged when rainwater invades the cracks.

[0032] In this embodiment, the water-soluble film 2 is a polyvinyl alcohol film. After the explosive particles are immersed in water, the polyvinyl alcohol film can dissolve over time, thereby releasing the microorganisms 5 therein.

[0033] In this embodiment, the microorganisms 5 include Bacillus sphaericus and Sporosarcina pasteurii. Bacillus sphaericus and Sporosarcina pasteurii have a powerful self-healing function and are widely used in crack repair. The nutrient 4 includes yeast extract. During production, the microorganisms 5 are encapsulated in the form of spores. At this time, the spores are in a dormant state, and only yeast extract is required as the nutrient. When a large amount of water is replenished in the crack 6 during the flood season, the activity of the spores will be activated, and a urease hydrolysis reaction will occur to generate calcium carbonate precipitation, realizing the repair of the crack 6.

[0034] A preparation method of the explosive particles for repairing rock mass cracks using water pressure as described above includes the following steps:

[0035] (1) First, prepare the inner layer material of the explosive particles. Take an appropriate amount of urea 3 and add it to an aqueous sodium alginate solution. Stir evenly on a magnetic stirrer (rotation speed 160 r / min). While stirring, the obtained suspension is dropped into a 0.2% calcium chloride aqueous solution at a speed of 20 ml per hour using a syringe. After adding, continue to stir for 5 min, filter, wash with water to obtain a pale yellow hydrogel, and dry it naturally at room temperature to obtain a calcium alginate dry gel encapsulated with urea.

[0036] (2) First, cultivate the required microorganisms into a spore state. Bacillus sphaericus spores are produced in a liquid minimal basal salt (MBS) medium. Before use, the MBS medium is autoclaved at 120 °C for 20 minutes. Transfer the mature spores as an inoculum (1%) to the MBS medium, incubate the culture (28 °C, 100 rpm) for 28 days. Subsequently, subject them to pasteurization (80 °C for 20 minutes, then in ice-cold water for 5 minutes) to minimize the vegetative cells. Then, harvest the spores by centrifuging the culture (7000 rpm, 4 °C) for 7 min, remove the supernatant, and vacuum dry the spore paste at room temperature for 3 days. Then, grind the dry paste of the spores in a cement mill for 5 seconds to obtain spore powder for encapsulation.

[0037] (3) Prepare the outer wrapping material hydrogel. Add the calcium alginate dry gel wrapped with urea and spore powder into a certain amount of yeast extract (nutrients necessary for the survival of spores). Degas and mix the mixture (5 minutes, 500 rpm). Inject it into a chamber composed of two glass plates separated by a 1-mm-thick silicone gasket. After the substances are mixed, inject an aqueous solution of polyvinyl alcohol to completely cover the mixed solution. Then clamp the glass plates and perform ultraviolet irradiation for 1 hour. After the ultraviolet irradiation, explosive particles for repairing rock mass cracks by using water pressure are obtained.

[0038] A method for repairing rock mass cracks, which uses the explosive particles for repairing rock mass cracks by using water pressure described above for repair, and includes the following steps:

[0039] (1) Spray the water with explosive particles onto the rock wall, and the explosive particles flow into the crack 6 along with the water;

[0040] (2) As the explosive particles become saturated in the crack 6, the outer water-soluble film 2 gradually ruptures over time, releasing the microorganisms 5 therein. The microorganisms 5 combine with the calcium source in the crack wall 7 and adhere to the crack wall 7;

[0041] (3) As the water level rises, water flows into the crack 6, and the water pressure in the crack 6 gradually increases. The shear-resistant gel films 1 of the explosive particles in the crack 6 rupture successively from deep to shallow under the action of water pressure, releasing the internal urea 3. The urea 3 produces carbonate ions under the action of microbial urease. The carbonate ions react chemically with the calcium source on the crack wall 7 to generate calcium carbonate crystals 8, which adhere to the crack wall 7, and the crack 6 is repaired from deep to shallow.

[0042] In step (1), use a spraying device to spray the water with explosive particles onto the rock wall. Since the outermost water-soluble film of the explosive particles is not affected by pressure, the explosive particles will not be damaged, and the microorganisms 5 (bacteria) in the internal nutrient solution can survive.

[0043] In step (2), after the bacteria are released, the combination of the bacteria with the calcium source in the crack wall can play a role in fixing the bacteria. This is because the positively charged calcium ions can neutralize the negative charge of the bacterial cell wall, making it easier for the bacteria to adsorb on the surface of the negatively charged sand and gravel particles and preventing the microorganisms from being washed away.

[0044] In step (3), the carbonate ions react chemically with the calcium source on the crack wall 7 immediately to generate calcium carbonate crystals 8. Since the microorganisms 5 are originally attached to the crack wall 7, the generated calcium carbonate crystals 8 also adhere to the crack wall 7 and are difficult to be carried away by the water flow, having a certain stability and making the effect of repairing the crack better.

[0045] When repairing cracks in the rock mass in the drawdown zone on both sides of the Yangtze River, explosive particles are injected into the cracks. The seasonal rainy season in the Yangtze River basin and the flood discharge and water storage rules of the Three Gorges Reservoir are used to make the water level rise and provide different water pressures, so that the explosive particles deep in the cracks are crushed first, and the substances are released to react, achieving the purpose of generating calcium carbonate crystal precipitation to repair the cracks.

[0046] The present invention provides the following test scheme to simulate the process of microbial treatment of the drawdown zone, and conducts measurement tests to observe the treatment effect of the drawdown zone.

[0047] 1. Production of the drawdown zone model and simulation environment

[0048] A 3D contour laser scanner was used to scan the surface of the drawdown zone (including cracks) in a specific area of the Yangtze River basin. A mold was then made based on the scan results. Sand and soil from the site were mixed at a specific water-soil ratio and injected into the mold. The resulting drawdown zone model resembled the actual drawdown zone. Multiple models were created using the same method for comparison in subsequent experiments. A square box with a water pipe running through it was used to simulate the fluctuations in the Yangtze River's water level during drought and flood seasons by pumping and injecting water.

[0049] 2. Microbial control test

[0050] A liquid containing explosive particles was sprayed into the cracks of one of the models using a micro-spray nozzle. The model was then placed vertically (with the crack extending perpendicular to the tabletop) in a square box. Over time, the outer water-soluble film 2 dissipated, releasing the microorganisms, which first reacted with the calcium source in the crack wall to immobilize the bacteria. After a period of time, water was injected into the box, and the inner shear-resistant gel film 1 was sheared by the water pressure, releasing urea. The urease (urea amidohydrolase - EC 3.5.1.5) contained in the microorganisms catalyzed the hydrolysis of urea into ammonia and carbon dioxide. The hydrolysis of one urea molecule results in the release of two ammonia molecules and one carbon dioxide molecule. The enzymatic hydrolysis of urea is generally described as follows:

[0051]

[0052] The release of ammonia by urea hydrolysis leads to an increase in pH in the surrounding medium, where the replenished mineral ions (Ca 2+ and CO3 2- ) can precipitate CaCO3. White fine crystals can be observed forming within the cracks. Four microbial-treated model samples were prepared sequentially, and these, along with the remaining untreated models from the first step, formed four control test groups.

[0053] 3. Governance Effect Measurement Test

[0054] The first group of test samples were observed using SEM (scanning electron microscope) to observe the surface morphology and microstructure of the cracks. Figure 3The SEM image inside the crack of the sample without microbial treatment is shown as follows. Figure 4 The SEM image inside the crack of the sample after microbial treatment is shown as follows. It can be confirmed that there is a good crystallization effect inside the crack of the sample after microbial treatment.

[0055] For the second group of samples, the water permeability rate was measured by a water permeability test. The outer periphery of the sample was sealed with a rubber sleeve and placed horizontally in a container with a size smaller than that of the sample. Then, water was slowly injected, and the mass of the water passing through the sample in the container was measured. The permeability decreased from the original 115×10 -12 m -2 to 29×10 -12 m -2 , . It can be clearly observed that the water permeability rate of the sample after microbial treatment is lower than that of the untreated sample.

[0056] For the third group of samples, the shear strength was measured by a direct shear test. The control samples were successively placed in a direct shear tester and slowly loaded until the samples were damaged. The untreated samples and the repaired samples were respectively subjected to shear tests under normal stresses of 50 kPa, 100 kPa, and 150 kPa. The relationship between the peak shear stress and the normal stress was obtained. According to the relationship between the two, the changes in cohesion and internal friction angle before and after repair were obtained. The cohesion range was between 128.64 - 142.72 kPa, which was about 25 times that before repair. The average shear strength was 0.28 MPa, which was 4 - 5 times that before repair.

[0057] In the present invention, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, based on the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. An explosive particle for repairing rock mass cracks using water pressure, characterized in that: It includes a shear-resistant gel film and a water-soluble film wrapped outside the shear-resistant gel film. The shear-resistant gel film is a calcium alginate gel film, and the water-soluble film is a polyvinyl alcohol film. Urea is encapsulated in the shear-resistant gel film. Nutrients and microorganisms with urease present in the body are provided between the shear-resistant gel film and the water-soluble film. The nutrients include yeast extract, and the microorganisms include Bacillus sphaericus and Sarcina pasteurii. When the external water pressure is greater than the shear strength of the shear-resistant gel film, the shear-resistant gel film ruptures to release the urea therein.

2. The preparation method of the explosive particles for repairing rock mass cracks by using water pressure according to claim 1, characterized in that, It includes the following steps: (1) Take urea and add it to an aqueous sodium alginate solution, stir evenly, drop the obtained suspension into an aqueous calcium chloride solution, stir, filter, wash with water to obtain a hydrogel, and naturally dry it at room temperature to obtain a calcium alginate dry gel encapsulated with urea. (2) Add the calcium alginate dry gel encapsulated with urea and spore powder to yeast extract. The spore powder is the spore-state powder of microorganisms with urease present in the body. After degassing and mixing, inject it into a chamber composed of two glass plates, and the two glass plates are separated by a silicone gasket. Inject an aqueous polyvinyl alcohol solution to completely cover the mixed solution, then clamp the glass plates and perform ultraviolet irradiation to obtain explosion particles for repairing rock mass cracks using water pressure.

3. The preparation method according to claim 2, characterized in that, The preparation method of the spore powder includes the following steps: Sterilize the MBS medium, transfer mature spores as inoculum to the MBS medium, incubate the culture, harvest the spores by centrifuging the culture, remove the supernatant, vacuum dry the spore paste at room temperature to obtain a dry paste of spores, and then grind the dry paste of spores to obtain spore powder for encapsulation.

4. A method for repairing rock mass cracks, characterized in that: Use the explosion particles for repairing rock mass cracks described in claim 1 for repair, including the following steps: (1) Spray water with explosion particles onto the rock wall, and the explosion particles flow into the cracks with the water. (2) As the explosion particles saturate in the cracks, the outer water-soluble film gradually ruptures over time, releasing the microorganisms therein. The microorganisms combine with the calcium source in the crack wall and adhere to the crack wall. (3) As the water level rises, water flows into the cracks, the water pressure in the cracks gradually increases, and the shear-resistant gel films of the explosion particles in the cracks rupture successively from deep to shallow under the action of water pressure, releasing the internal urea. The urea produces carbonate ions under the action of microbial urease. The carbonate ions react with the calcium source on the crack wall to generate calcium carbonate crystals, which adhere to the crack wall, and the cracks are repaired from deep to shallow.

Images