NL2031188B1

NL2031188B1 - Microbial reinforcement method of fractured rock masses

Info

Publication number: NL2031188B1
Application number: NL2031188A
Authority: NL
Inventors: Chen Hongjie
Original assignee: Huaneng Lancang River Hydropower Inc
Priority date: 2021-05-10
Filing date: 2022-03-08
Publication date: 2023-01-23
Also published as: CN113216979A; NL2031188A; CN113216979B

Abstract

The invention discloses a microbial reinforcement method of fractured rock masses. First, microbial concentrated liquid is injected into a fractured rock mass, and then a DSMZ nutrient solution and a consolidation nutrient solution are sequentially added. Herein, a microbial strain is Bacillus, and the consolidation nutrient solution can enhance the absorption effect on calcium ions by Bacillus and promote calcif1cation, thus achieving excellent cementing effect of the fractured rock mass.

Description

MICROBIAL REINFORCEMENT METHOD OF FRACTURED ROCK MASSES BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The invention relates to the technical field of fractured rock mass reinforcement, in particular to a microbial reinforcement method of fractured rock masses.

[0003] 2.Description of Related Art

[0004] Fractured rock masses develop on valley slope in plateau area, and the development depth increases with the increase of elevation. In case of natural conditions and construction interference, local rock blocks of a fractured rock mass may collapse at any time. On high and steep mountains, rockfall poses a great threat to the safety of engineering construction roads, personnel and equipment. Such a danger happens at any time and commonly exists in the whole mountains on both sides. Therefore, it is necessary to reinforce and treat the fractured rock masses.

[0005] When a traditional method is used to reinforce and treat the fractured rock masses all over the mountains on both sides, the project amount is huge, the construction period is extremely long, the cost is unacceptable, and the reinforcement effect is not ideal. In view of this situation, some researchers have used a microbial reinforcement technology to reinforce the fractured rock masses. Compared with a traditional reinforcement method of the fractured rock masses, the adoption of microbial mineralization to cement the fractured rock masses can not only enhance the integrity and strength of rock masses, but also has the characteristics of being strong in operability and environmental friendly, and has extremely high application value.

[0006] Although the microbial reinforcement of the fractured rock masses has a good application prospect, the cementing effect of the current microbial reinforcement method on the fractured rock masses is still not ideal.

BRIEF SUMMARY OF THE INVENTION

[0007] The invention aims to provide a microbial reinforcement method of fractured rock masses, for solving above problems in the prior art, thereby significantly improving the cementing effect of microbial reinforcement on the fractured rock masses.

[0008] In order to achieve the above object, the invention provides a scheme as 1 follows:

[0009] A consolidation nutrient solution includes the following components and contents: 9-11 g/L of tryptone, 2-3 g/L of soybean peptone, 48-50 g/L of anhydrous calcium chloride, 33-35 g/L of urea, 8-10 g/L of methyl -a-D- glucopyranoside, 0.4-0.5 g/L of tea saponin and the balance of water.

[0010] A microbial reinforcement method of fractured rock masses includes the following steps:

[0011] Injecting microbial concentrated liquid into a fractured rock mass, and then adding a DSMZ nutrient solution and a consolidation nutrient solution sequentially;

[0012] The microbial concentrated liquid is any concentrated liquid of Bacillus pasteurii, Alkaline Bacillus, Bacillus licheniformis or Bacillus subtilis; the density of the microbial concentrated liquid is 2.0-2.6 x 10”cells/ml;

[0013] the consolidation nutrient solution is above-mentioned consolidation nutrient solution.

[0014] Furthermore, the volumetric ratio of the microbial concentrated liquid, the DSMZ nutrient solution and the consolidation nutrient solution is 1:8-10:5-6.

[0015] Furthermore, the microbial concentrated liquid is a Bacillus pasteurii concentrated liquid.

[0016] Furthermore, an injection pipe is adopted for auxiliary injection into the fractured rock mass.

[0017] The invention further proposes an application of the above consolidation nutrient solution to fractured rock mass reinforcement.

[0018] The invention discloses the following technical effects:

[0019] Since tea saponin has affinity to cell membrane, the bactericidal and antibacterial effects of tea saponin are usually used in the prior art. According to the invention, methyl -a-D- glucopyranoside and tea saponin are added into the nutrient solution, and it 1s found that in the presence of methyl -a-D- glucopyranoside, a control over the addition of tea saponin in a minor amount can promote the absorption on the calcium ions by Bacillus and enhance the calcification, thus significantly enhancing the cementing effect.

[0020] The invention makes full use of the natural mineralization of microorganisms to achieve restoration without the release of toxic and harmful gases, meets the requirements of ecological balance and environmental friendliness, avoids massive cement grouting materials or chemical grouting materials, and has important guiding significance 2 for the green treatment and protection of dangerous rock masses.

[0021] Aiming at the reinforcement of the fractured rock masses, the invention can be applied to the fields of reinforcement and treatment of engineering slopes such as hydropower engineering slopes, road engineering slopes and railway slopes; reinforcement and treatment of surrounding rocks of diversion tunnels, traffic tunnels and oil reserve caverns, treatment of dangerous rock masses in scenic spots; and port and waterway engineering construction, coastal reclamation, island reef development, desert control, sandstorm control and the like.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0022] FIG. 1 is a schematic diagram of an application in engineering of a bio-reinforcement mode in the present invention;

[0023] FIG. 2 is a schematic diagram ofprinciple of bio-reinforcement calcification in the present invention;

[0024] FIG. 3 is a fractured rock sample before microbial reinforcement in embodiment 1; and

[0025] FIG. 4 is a cemented rock sample after microbial reinforcement in embodiment 1.

DETAILED DESCRIPTION OF THE INVENTION

[0026] Now, a detailed description is made to various exemplary embodiments of the present invention. This detailed description should not be considered as a limitation to the present invention, but should be understood as a more detailed description of some aspects, characteristics and implementation plans of the present invention.

[0027] It should be understood that the terms used in the present invention are only for describing specific embodiments, rather than limiting the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Any stated value or intermediate value within a stated range and any other stated value or every smaller range between intermediate values within the stated range are also included in the present invention. The upper and lower limits of these smaller ranges can be independently included in or excluded from the range.

[0028] Unless otherwise defined, all technological and scientific terms used herein 3 have meanings the same as those usually understood by those of conventional skill in the art of the present invention. Although the present invention only describes the preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in the present specification are incorporated by reference so as to disclose and describe the methods and/or materials related to the documents. In case of conflict with any incorporated documents, the contents of the present specification shall prevail.

[0029] It is apparent to those skilled in the art that many modifications and variations can be made to the specific embodiments of the specification of the present invention without departing from the scope or spirit of the present invention. Other embodiments obtained from the specification of the present invention are apparent to the skilled persons. The specification and embodiments of the present invention are only exemplary.

[0030] “Comprising”, “including”, “having”, “containing” and other words used herein are all open terms, that is, they mean including but not limited to.

[0031] The microbial reinforcement method of fractured rock masses in the present invention includes the following steps in engineering implementation:

[0032] 1. Select, according to the influence of engineering importance and structural stability of slope rock masses, the range of fractured rock masses to be reinforced.

[0033] 2. Within the selected range, insert grouting steel floral tubes (25mm, 32mm, 48mm, 60mm, etc. in diameter according to the fracture size) according to the row spacing of about 2m, and then fill fractures in the fractured rock mass by sandy soil and other materials.

[0034] 3. Prepare the microbial concentrated liquid: perform resuscitation culture on a frozen strain, then prepare the microbial concentrated liquid with the bacterial density of

2.0-2.6 x 10° cellsml by a DSMZ cultured fluid, and refrigerate the microbial concentrated liquid at 4 °C for later use;

[0035] the strain used is one of Bacillus pasteuri, Alkaline Bacillus, Bacillus licheniformis or Bacillus subtilis;

[0036] Herein, Bacillus pasteurii concentrated liquid is prepared by the following steps: firstly, perform resuscitation culture on a Bacillus pasteurii strain adsorbed by ceramic beads and frozen in a refrigerator at -80 °C, then inject the strain into a container containing the DSMZ cultured fluid, which has been sterilized at a high temperature in 4 advance, place the container in an incubator shaker, keep oscillation at a constant temperature of 30 °C for 10 hours and then take the container out. Transfer the container to a high-speed centrifuge for separation (the rotating speed is about 6000 rpm/min), pour out excess liquid, and blow it evenly with a pipettor to finally obtain the Bacillus pasteurii concentrated liquid with the bacterial density of 2.0-2.6 x 10° cells/ml, and refrigerate same in a 4 °C environment for later use.

[0037] 4. Prepare consolidation nutrient solution:the consolidation nutrient solution has a formula: 9-11g/L of tryptone, 2-39/L of soybean peptone, 48-509/L of anhydrous calcium chloride, 33-35g/L of urea, 8-10g/L of methyl -a-D- glucopyranoside, 0.4-0.5g/L of tea saponin and the balance of water. In order to reduce the application cost and facilitate site construction, the site water source is used as preparation water, and the selected water source should be as clean as possible and filtered for use. Ordinary tap water should not be used as the water source as residual hypochlorous acid therein can inhibit microorganisms.

[0038] 5. Firstly, inject the microbial concentrated liquid prepared in step 3 into the steel floral tube, and then inject the DSMZ nutrient solution which is 8-10 times the volume of the microbial concentrated liquid. This step mainly aims at activating the biological activity of Bacillus pasteurii and sandy soil indigenous microorganisms as soon as possible, and introducing the Bacillus pasteurti into the sandy soil and fractures of rock masses by the pressure difference produced by injection of the nutrient solution. During nutrient solution injection, the adoption of the principle of small amount and multiple times ensures certain injection pressure, and the amount of the DSMZ nutrient solution added each time is gradually reduced until the injection is completed. If the Bacillus pasteurii concentrated liquid is insufficient, it can be supplemented at any time in the later stage.

[0039] 6. Inject the prepared consolidation nutrient solution: after the DSMZ nutrient solution is injected, continue to inject the consolidation nutrient solution which is 5-6 times the volume of the microbial concentrated liquid. During the injection, the principle of small amount and multiple times is also adopted, and the amount of the consolidation nutrient solution added each time is gradually reduced until the injection is completed. The prepared consolidation nutrient solution should be used as soon as possible, so as to avoid the deterioration of components from affecting the effect.

[0040] 7. Perform sampling inspection on filling of microbial mineralization products to the gap of an accumulation slope, and in case of non-ideal filling, (for example, 5 sandstone and the fractured rock mass are not bonded together, or the cementing amount of the fractured rock mass is less than half of the area), arrange new holes around for re-filling.

[0041] 8. When the solution injected in the steel floral tube dries up, inject concrete mortar, and seal the grouting steel floral tube.

[0042] 9. If all sampling inspection qualified, end the reinforcement of the fractured rock masses.

[0043] Fig. 1 is a schematic diagram of an application in engineering of a bio-reinforcement mode in the present invention and Fig. 2 is a schematic diagram of bio-reinforcement calcification principle in the present invention.

[0044] Taking American dacite as an example, the microbial fractured rock mass reinforcement effect in the present invention is compared.

[0045] In the following embodiments, an American dacite fractured rock sample is processed into a cylindrical fractured rock sample with a height of SOmm and a diameter of 50mm.

[0046] Embodiment 1:

[0047] Inthe embodiment, the consolidation nutrient solution includes the following components:

[0048] 9g/L of tryptone, 29/L of soybean peptone, 50g/L of anhydrous calcium chloride, 34g/L of urea, 8g/L of methyl -a-D- glucopyranoside, 0.5g/L of tea saponin and the balance of water.

[0049] Microbial reinforcement of fractured rock masses:

[0050] (1) the fractured rock sample was soaked in distilled water for 24h to remove impurities on the surface of the sample;

[0051] (2) two petals of the fractured rock sample were aligned and then pushed into a sleeve with an inner diameter of 50mm; the bottom of the sample was padded with permeable stone and flush with the bottom of the sleeve; and the top of the sleeve was provided with a hanging needle dropper;

[0052] (3) 15mL of Bacillus pasteurii concentrated liquid (the concentration of the bacterial solution is 2.6x10° cells/ml) was added into the sleeve at a rate of 0.50mL/min;

[0053] (4) after adding the Bacillus pasteurii concentrated liquid dropwise, 150mL of DSMZ nutrient solution was added into the sleeve at a rate of 2mL/min, and then stood for 0.5h after adding;

[0054] (5) after standing, 90mL of consolidation nutrient solution was added into the 6 sleeve at a rate of lmL/min, and stood for 0.5h after dropping dropwise,thus completing microbial reinforcement of the fractured rock masses.

[0055] Fig. 3 is a fractured rock sample before microbial reinforcement in the embodiment, and Fig. 4 is a cemented rock sample after microbial reinforcement.

[0056] Embodiment 2:

[0057] Inthe embodiment, the consolidation nutrient solution includes the following components:

[0058] 11g/L of tryptone, 3g/L of soybean peptone, 48g/L of anhydrous calcium chloride, 35g/L of urea, 9g/L of methyl -a-D- glucopyranoside, 0.4g/L of tea saponin and the balance of water.

[0059] Microbial reinforcement of fractured rock masses:

[0060] (1)the fractured rock sample was soaked in distilled water for 24h to remove impurities on the surface of the sample;

[0061] (2)two petals of the fractured rock sample were aligned and then pushed into a sleeve with an inner diameter of 50mm; the bottom of the sample was padded with permeable stone and flush with the bottom of the sleeve; and the top of the sleeve was provided with a hanging needle dropper;

[0062] (3)15mL of Bacillus pasteuri concentrated liquid (the concentration of the bacterial solution is 2.0x10° cells/ml) was added into the sleeve at a rate of 0.50mL/min;

[0063] (4) after adding the Bacillus pasteurii concentrated liquid dropwise, 120mL of DSMZ nutrient solution was added into the sleeve at a rate of 2mL/min, and then stood for

0.5h after adding;

[0064] (5) after standing, 75mL of consolidation nutrient solution was added into the sleeve at a rate of mL/min, and stood for 0.5h after dropping dropwise,thus completing microbial reinforcement of the fractured rock masses.

[0065] Embodiment 3:

[0066] Inthe embodiment, the consolidation nutrient solution includes the following components:

[0067] 10g/L of tryptone, 2g/L of soybean peptone, 499/L of anhydrous calcium chloride, 33g/L of urea, 10g/L of methyl -a-D- glucopyranoside, 0.5g/L of tea saponin and the balance of water.

[0068] Microbial reinforcement of fractured rock masses:

[0069] (1)the fractured rock sample was soaked in distilled water for 24h to remove impurities on the surface of the sample; 7

[0070] (2)two petals of the fractured rock sample were aligned and then pushed into a sleeve with an inner diameter of 50mm; the bottom of the sample was padded with permeable stone and flush with the bottom of the sleeve; and the top of the sleeve was provided with a hanging needle dropper;

[0071] (3)15mL of Bacillus subtilis concentrated liquid (the concentration of the bacterial solution is 2.4x10° cells/ml) was added into the sleeve at a rate of 0.50mL/min;

[0072] (4) after adding the Bacillus pasteurii concentrated liquid dropwise, 140mL of DSMZ nutrient solution was added into the sleeve at a rate of 2mL/min, and then stood for

0.5h after adding;

[0073] (5) after standing, 80mL of consolidation nutrient solution was added into the sleeve at a rate of mL/min, and stood for 0.5h after dropping dropwise thus completing microbial reinforcement of the fractured rock masses.

[0074] Comparative example 1

[0075] The only difference from embodiment 1 is that no methyl -a-D- glucopyranoside is added.

[0076] Comparative example 2

[0077] The only difference from embodiment 1 is that no tea saponin is added.

[0078] Comparative example 3

[0079] The only difference from embodiment 1 is that the content of tea saponin is lg.

[0080] Related performance data of the fractured rock masses reinforced by embodiments 1-3 and comparative examples 1-3 are shown in Table 1: 8

Table 1 Calcium Uniaxial compressive carbonate Permeability coefficient strength/MPa content/% Embodiment .

34.29 (3.2-4.5)x 105 cm/s I: Embodiment <

6.7 33.56 (3.6-4.6)<10 cm/s 2: Embodiment 5

33.45 (3.7-4.7)x10% cm/s 3: Comparative |

2.1 9.21 (0.3-2.1)~10™ cm/s example 1 Comparative 4

3.2 12.36 (0.3-1.9)x10™ cm/s example 2 Comparative 4

2.9 10.42 (0.2-1.8)x10% cm/s example 3 The above embodiments only describe the preferred mode of the present invention, rather than limiting the scope of the present invention. Various modifications and improvements made for the technical solutions of the present invention by those of ordinary skill in the art shall all fall within the scope of protection determined by claims of the present invention without departing from the design spirit of the present invention. 9

Claims

Conclusions:

1. A fortifying nutrient solution containing the following components and composition: Tryptone 9-11 g/L, soybean peptone 2-3 g/L, anhydrous calcium chloride 48-50 g/L, urea 33-35 g/L, methyl-a-D- glucopyranoside 8-10 g/L and tea saponin 0.4-0.5 g/L, the rest is water.

2. A microbial strengthening method of a fractured rock mass, characterized in that it comprises the following steps: injecting a concentrated solution of microbial strains into the fractured rock mass, and then adding a DSMZ nutrient solution and a strengthening nutrient solution; the concentrated solution of microbial is any concentrated solution of Bacillus pastorianus, Bacillus alcalis, Bacillus licheniformis or Bacillus subtilis; the density of the concentrated microbial solution is 2.0-2.6 » 10° cells/ml; the fortifying nutrient solution is the fortifying nutrient solution according to claim 1.

The microbial reinforcement method of a fractured rock mass according to claim 2, characterized in that the volume ratio of the concentrated solution of microbial, the DSMZ nutrient solution and the consolidated nutrient solution is 1:8-10:5-61s.

The microbial reinforcement method of a fractured rock mass according to claim 2, characterized in that the concentrated solution of microbial strains is a concentrated solution of Bacillus pastorianus.

The microbial reinforcement method of a fractured rock mass according to claim 2, characterized in that an injection pipe is adapted for auxiliary injection into the fractured rock mass.

Use of the consolidated nutrient solution according to claim 1 in the reinforcement of a fractured rock massif.

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