A kind of microbial mineralized bamboo soil nail for slope reinforcement and its preparation method and application

Abstract

The invention discloses a microbial mineralized bamboo soil nail for slope reinforcement and a preparation method and application thereof, and belongs to the technical field of slope reinforcement. The preparation method comprises the following steps: firstly, a soil nail hole is dug in the soil body of the slope to be reinforced, and bamboo is placed therein; then, microbial bacterial solution I, magnesium oxide, quartz sand and urea are evenly mixed to obtain microbial mortar; then, the microbial mortar is injected into the soil nail hole; finally, microbial bacterial solution II and a cementing liquid are sprayed on the surface of the soil body for maintenance to obtain the soil nail. The invention combines urease-producing microorganisms with bamboo, and has the advantages of being green, environmentally friendly, stable, reliable, and having low cost; the bamboo soil nails are arranged in a plum blossom shape, which effectively enhances the stability of the soil slope, solidifies the soil surface by surface microbial culture solution, combines bamboo soil nails and microbial grouting, and reduces environmental pollution while improving the stability of the slope, effectively preventing the slope from landslides when it rains, and not only effectively stabilizing the slope, but also achieving harmonious coexistence with the natural ecology.

Description

Technical Field

[0001] The invention relates to the technical field of slope reinforcement, and in particular to a slope reinforcement microbial mineralized bamboo soil nail and a preparation method and application thereof. Background Art

[0002] The harmonious coexistence of civil engineering and ecological nature has become an important topic in recent years. Bio-construction is an emerging direction proposed in recent years. Its concept focuses on the harmonious coexistence of civil engineering and natural ecology, and advocates low-carbon, efficient and innovative construction methods. Microbial construction and plant construction are popular directions in the field of bio-construction. Compared with traditional construction methods, they can effectively reduce energy consumption and resource waste, and realize the concept of harmonious coexistence with ecological nature.

[0003] The technology based on microbial induced calcium carbonate deposition (MICP) has set off a research boom in the field of geotechnical engineering. This technology is a cross-application of geotechnical engineering and microbiology, and is considered to be effectively applied in biological construction. The principle of this technology is mainly to use urease produced by urease-producing microorganisms to catalyze the hydrolysis of urea to produce carbonate ions, while combining with abundant calcium ions in the environment to form calcium carbonate precipitation; the generated calcium carbonate precipitation has good mechanical properties and can quickly cement soil particles.

[0004] In slope engineering, the most widely used slope reinforcement form is soil nail wall. Traditional soil nail wall has the characteristics of high material cost, high construction condition requirements and great pollution to the surrounding area. In the field of plant construction, bamboo is a natural composite material with high multi-layer gradient structure. The vascular bundles and fibers in the bamboo structure also make bamboo have excellent mechanical properties. Among them, bamboo's good tensile properties and corrosion resistance make it possible to be used as a soil nail force structure.

[0005] The prior art with the publication number CN105862887B discloses an ionic rare earth mine ecological slope protection structure, which includes: (1) arranging bamboo piles or bamboo rafts into a bamboo frame and pressing them into the soil; (2) arranging ecological planting bags in the bamboo piles above the first bamboo node and setting water seepage holes on the bamboo pile wall, and the grass seed substrate composition and weight ratio in the biological planting bag are: clay 40%-50%, 20-30%, plant ash 10%-30%, sawdust 10%-20%, water 5%-15%, grass seed 0.01%-1%. This method only reinforces and solidifies the soil at a depth of 2-10 cm on the surface, and the depth is shallow. The prevention and control method is single and limited to rare earth mines. For slopes of other soils, this method does not propose a solution.

[0006] The prior art with publication number CN113882407A discloses a landslide prevention method based on microbial mineralization, which includes: (1) spraying microbial liquid and cementing liquid on the soil surface in sequence; (2) injecting microbial liquid and cementing liquid into the potential sliding surface of the soil in sequence; (3) making a pile hole in the soil, pouring sand into the pile hole, and then injecting microbial liquid and cementing liquid into the pile hole in sequence to obtain a sand anti-slide pile; (4) setting a lattice on the soil surface, and then spraying microbial liquid and cementing liquid on the lattice in sequence to obtain a sand lattice; and (5) setting a sand drainage ditch and a sand intercepting ditch in the soil, and spraying microbial liquid and cementing liquid on the sand drainage ditch and the sand intercepting ditch in sequence. This method uses sand anti-slide piles, which still have some problems in strength and rainwater erosion resistance, and the cultivation of microbial liquid has the problem of poor microbial survival.

[0007] In summary, a slope reinforcement method that combines microbial mortar and bamboo with high strength, environmental protection and strong stability needs to be developed urgently. Summary of the invention

[0008] In order to solve the above technical problems, the purpose of the present invention is to provide a slope reinforcement microbial mineralized bamboo soil nail and its preparation method and application, so as to solve the problems of poor applicability, weak reinforcement strength and poor erosion resistance of existing slope reinforcement methods.

[0009] The technical solution of the present invention to solve the above technical problems is as follows:

[0010] A method for preparing microbial mineralized bamboo soil nails for slope reinforcement comprises the following steps:

[0011] First, soil nail holes are dug in the soil of the slope to be reinforced and bamboo is placed in them; then, microbial solution I, magnesium oxide, quartz sand and urea are evenly mixed to obtain microbial mortar; then, the microbial mortar is injected into the soil nail holes; finally, microbial solution II and a binder are sprayed on the soil surface for curing to obtain the product.

[0012] The present invention combines urease-producing microorganisms with bamboo to obtain a bamboo soil nail based on microbial mineralization. Compared with conventional traditional soil nails, the bamboo soil nails prepared by the present invention have the advantages of being green, environmentally friendly, stable, reliable, and low in cost.

[0013] Furthermore, when the diameter of the bamboo material is greater than 100 mm, grouting holes are arranged on the wall of the bamboo tube within a range of 1 / 4-1 / 2 of the length from the bottom of the bamboo tube, with a diameter of 10-15 mm and a spacing of 400-500 mm.

[0014] Furthermore, both microbial culture liquid I and microbial culture liquid II are culture liquids of Bacillus sporosarcina, and the enzyme activity level is 0.8-1.2 mS / min, OD 600 0.5-5.0Abs.

[0015] Furthermore, the quartz sand is obtained by mixing primary sand with a particle size of 0.25-0.35 mm, secondary sand with a particle size of 0.35-0.5 mm and tertiary sand with a particle size of 0.5-1 mm; the mass ratio of the primary sand, the secondary sand and the tertiary sand is 1-3:0.5-2:0.5-2.

[0016] Preferably, the mass ratio of primary sand, secondary sand and tertiary sand is 2:1:1.

[0017] Furthermore, the addition amount of magnesium oxide is 5%-10% of the mass of quartz sand; the addition amount of microbial solution I is 30-50% of the total volume of microbial mortar; the concentration of urea is 0.5-2 mol / L, and the addition amount is equal to the addition amount of microbial solution I.

[0018] Preferably, the addition amount of magnesium oxide is 8% of the mass of quartz sand; the addition amount of microbial solution I is 40% of the total volume of microbial mortar; the concentration of urea is 1 mol / L, and the addition amount is equal to the addition amount of microbial solution I.

[0019] Furthermore, the binder liquid is a mixed solution of urea and calcium chloride, the concentration of urea is 1 mol / L, and the concentration of calcium chloride is 1 mol / L.

[0020] Furthermore, the spraying conditions of the microbial liquid II and the cementing liquid are as follows: first spray the microbial liquid II at a rate of 40-60 mL / min, let it stand for 1-3 hours after spraying, then spray the cementing liquid at a rate of 40-60 mL / min, react for 10-12 hours, and finally spray the cementing liquid again at a rate of 40-60 mL / min; repeat the spraying of the microbial liquid II and the cementing liquid 1-3 times.

[0021] Preferably, the spraying conditions of microbial liquid II and the binder are: first spray the microbial liquid II at a rate of 50 mL / min, let it stand for 2 hours after spraying, then spray the binder at a rate of 50 mL / min, react for 11 hours, and finally spray the binder again at a rate of 50 mL / min; repeat the spraying of microbial liquid II and the binder twice.

[0022] Furthermore, the curing temperature is 5-40°C and the curing time is 10-20 days.

[0023] Preferably, the curing time is 14 days.

[0024] A microbial mineralized bamboo soil nail for slope reinforcement is prepared by adopting the preparation method.

[0025] The above-mentioned slope reinforcement microbial mineralized bamboo soil nails are used in slope reinforcement.

[0026] Furthermore, the horizontal and vertical spacings between the bamboo soil nails used for slope reinforcement are both 1.2-2 m.

[0027] Furthermore, the bamboo soil nails used for slope reinforcement are arranged in a plum blossom shape.

[0028] The beneficial effect of adopting the above-mentioned further technical solution is as follows: the present invention arranges bamboo soil nails in a plum blossom shape and adopts a combination of microbial mortar and microbial liquid spraying, thereby reducing environmental pollution while improving slope stability and effectively preventing slope landslides when it rains.

[0029] The present invention has the following beneficial effects:

[0030] (1) The present invention provides a bamboo soil nail based on microbial mineralization. By combining urease-producing microorganisms with bamboo, the present invention has the advantages of being green, environmentally friendly, stable, reliable, and low in cost compared to traditional soil nails.

[0031] (2) The present invention provides a method for slope reinforcement using bamboo soil nails based on microbial grouting. The bamboo soil nails are arranged in a plum blossom shape, which effectively enhances the stability of the soil slope. At the same time, the soil surface is solidified by spraying the surface microbial culture solution. The combination of bamboo soil nails and microbial grouting can reduce environmental pollution while improving the stability of the slope, effectively preventing the slope from sliding when it rains, and making the soil solidified completely, which not only achieves the purpose of stabilizing the slope, but also realizes harmonious coexistence with the natural ecology. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of plum blossom-shaped distribution of bamboo soil nails during slope reinforcement in the embodiment;

[0033] Figure 2 Schematic diagram of the structure of reinforcing a sandy soil slope by bamboo soil nails in Example 1, wherein 1 is the main body of the bamboo soil nail, 2 is the microbial liquid reinforcement layer on the slope surface, 3 is the soil nail hole, and 4 is the soil slope sliding surface;

[0034] Figure 3 Schematic diagram of the structure of reinforcing a clay slope by bamboo soil nails in Example 2, wherein 1 is the main body of the bamboo soil nail, 2 is the microbial liquid reinforcement layer on the slope surface, 3 is the soil nail hole, and 4 is the sliding surface of the soil slope. DETAILED DESCRIPTION

[0035] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0036] Embodiment 1:

[0037] A method for slope reinforcement based on microbial mineralized bamboo soil nails, comprising the following steps:

[0038] The soil for slope reinforcement in this embodiment is a 30° slope, sandy soil, and the soil permeability coefficient is 6.0×10 -4 cm / s, the engineering environment temperature is 25℃, and the slope stability is relatively poor.

[0039] (1) A grouting hole with a diameter of 10 cm is first opened in the soil. The potential sliding surface of the soil is calculated according to the limit equilibrium method of on-site investigation. The soil to be treated is sampled from the sliding surface. The porosity of the soil is measured to be 60%. Then, a bamboo soil nail with a diameter of 5 cm is obliquely inserted into the grouting hole. Since the diameter of the bamboo used in this embodiment is less than 10 cm, there is no need to open a grouting hole.

[0040] (2) The culture medium (1 L) consisted of the following components: 20 g yeast extract, 15 g ammonium chloride, 1 × 10 nickel chloride -3 mol, the balance is water, after stirring evenly, adjust the pH value of the medium to 9.12, and then sterilize at high temperature, and cool to room temperature after sterilization. Inoculate pasteurian spore Sarcina in the medium, culture at 30℃ and 200rpm, and obtain bacterial liquid after 18h, the enzyme activity level is 1mS / min, OD 600 It is 2.5Abs.

[0041] (3) 10 kg of first-grade quartz sand (particle size of 0.25-0.35 mm), 5 kg of second-grade sand (particle size of 0.35-0.5 mm) and 5 kg of third-grade sand (particle size of 0.5-1 mm) are added into a mixer, and then 1.6 kg of magnesium oxide is added. Finally, equal volumes of the bacterial solution obtained in step (3) and 1 mol / L urea solution (the bacterial solution and urea solution each account for 40% of the volume of the total microbial slurry) are added, and the mixture is stirred and mixed to obtain a microbial mortar.

[0042] (4) First, inject the microbial mortar into the inside and outside of the bamboo soil nails using a pouring machine, then use an electric sprayer to manually spray the bacterial solution obtained in step (3) at a speed of 50 mL / min, and let it stand for 2 hours. Then, spray the binder (a mixed solution of 1 mol / L urea and 1 mol / L calcium chloride) at the same speed. After reacting for 11 hours, spray the binder again (a mixed solution of 1 mol / L urea and 1 mol / L calcium chloride). Repeat the spraying of the microbial solution and the binder once, and then cure in an environment of 25°C for 14 days.

[0043] (5) Repeat the above steps with a spacing of 2m and a plum blossom pattern (e.g. Figure 1 As shown in the figure, multiple bamboo soil nails are arranged to reinforce the slope. Figure 2shown.

[0044] Embodiment 2:

[0045] A method for slope reinforcement based on microbial mineralized bamboo soil nails, comprising the following steps:

[0046] The soil for slope reinforcement in this embodiment is a 45° slope, sandy soil, and the soil permeability coefficient is 1×10 -6 cm / s, the engineering environment temperature is 25℃, and the slope stability is relatively poor.

[0047] (1) A grouting hole with a diameter of 15 cm was first opened in the soil. The potential sliding surface of the soil was calculated according to the limit equilibrium method based on the on-site investigation. The soil to be treated was sampled from the sliding surface. The porosity of the soil was measured to be 60%. Then, a bamboo soil nail with a diameter of 11 cm was obliquely inserted into the grouting hole. Since the diameter of the bamboo used in this embodiment was greater than 10 cm, a grouting hole was made at a distance of 1 / 3 from the bottom of the bamboo tube. The diameter of the grouting hole was 10 mm and the spacing was 400 mm.

[0048] (2) The culture medium (1 L) consisted of the following components: 20 g yeast extract, 15 g ammonium chloride, 1 × 10 nickel chloride -3 mol, the balance is water, after stirring evenly, adjust the pH value of the medium to 9.12, and then sterilize at high temperature, and cool to room temperature after sterilization. Inoculate pasteurian spore Sarcina in the medium, culture at 30℃ and 200rpm, and obtain bacterial liquid after 18h, the enzyme activity level is 1mS / min, OD 600 It is 2.5Abs.

[0049] (3) 20 kg of first-grade quartz sand (particle size of 0.25-0.35 mm), 10 kg of second-grade sand (particle size of 0.35-0.5 mm) and 10 kg of third-grade sand (particle size of 0.5-1 mm) are added into a mixer, followed by 3.2 kg of magnesium oxide, and finally, equal volumes of the bacterial solution obtained in step (3) and 1 mol / L urea solution (the bacterial solution and urea solution each account for 40% of the total volume of the microbial slurry) are added, and the mixture is stirred and mixed to obtain a microbial mortar.

[0050] (4) First, inject the microbial mortar into the inside and outside of the bamboo soil nails using a pouring machine, then use an electric sprayer to manually spray the bacterial solution obtained in step (3) at a speed of 50 mL / min, and let it stand for 2 hours. Then, spray the binder (a mixed solution of 1 mol / L urea and 1 mol / L calcium chloride) at the same speed. After reacting for 11 hours, spray the binder again (a mixed solution of 1 mol / L urea and 1 mol / L calcium chloride). Repeat the spraying of the microbial solution and the binder once, and then cure in an environment of 25°C for 14 days.

[0051] (5) Repeat the above steps and arrange multiple bamboo soil nails in a plum blossom shape with a spacing of 2m to reinforce the slope. Figure 3 shown.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing microbial mineralized bamboo soil nails for slope reinforcement, characterized in that: The following steps are involved: First, soil nail holes are dug in the soil of the slope to be reinforced and bamboo is placed in them; then, microbial solution I, magnesium oxide, quartz sand and urea are evenly mixed to obtain microbial mortar; then, the microbial mortar is injected into the soil nail holes; finally, microbial solution II and a binder are sprayed on the soil surface for curing to obtain the product.

2. The method for preparing the slope reinforcement microbial mineralized bamboo soil nails according to claim 1, characterized in that: When the diameter of the bamboo material is greater than 100 mm, grouting holes are arranged on the wall of the bamboo tube within the range of 1 / 4-1 / 2 of the length from the bottom of the bamboo tube, the diameter of the grouting holes is 10-15 mm, and the spacing is 400-500 mm.

3. The method for preparing the slope reinforcement microbial mineralized bamboo soil nails according to claim 1, characterized in that: The microbial culture liquid I and the microbial culture liquid II are both culture liquids of Bacillus pasteurianus, and the enzyme activity level is 0.8-1.2 mS / min, OD 600 0.5-5.0Abs.

4. The method for preparing the slope reinforcement microbial mineralized bamboo soil nails according to claim 1, characterized in that: The quartz sand is obtained by mixing first-grade sand with a particle size of 0.25-0.35 mm, second-grade sand with a particle size of 0.35-0.5 mm and third-grade sand with a particle size of 0.5-1 mm; the mass ratio of the first-grade sand, the second-grade sand and the third-grade sand is 1-3:0.5-2:0.5-2.

5. The method for preparing the slope reinforcement microbial mineralized bamboo soil nails according to claim 1, characterized in that: The addition amount of the magnesium oxide is 5%-10% of the mass of the quartz sand; the addition amount of the microbial solution I is 30-50% of the total volume of the microbial mortar; the concentration of the urea is 0.5-2 mol / L, and the addition amount is equal to the addition amount of the microbial solution I.

6. The method for preparing the microbial mineralized bamboo soil nails for slope reinforcement according to claim 1, characterized in that: The spraying conditions of microbial liquid II and cementing liquid are as follows: first spray microbial liquid II at a rate of 40-60 mL / min, let stand for 1-3 hours after spraying, then spray the cementing liquid at a rate of 40-60 mL / min, react for 10-12 hours, and finally spray the cementing liquid again at a rate of 40-60 mL / min; repeat the spraying of microbial liquid II and cementing liquid 1-3 times.

7. The method for preparing the slope reinforcement microbial mineralized bamboo soil nails according to claim 1, characterized in that: The curing temperature is 5-40° C. and the curing time is 10-20 days.

8. A microbial mineralized bamboo soil nail for slope reinforcement, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the slope reinforcement microbial mineralized bamboo soil nails according to claim 8 in slope reinforcement.

10. The use according to claim 9, characterized in that: The horizontal and vertical spacing between bamboo soil nails used for slope reinforcement are both 1.2-2m.

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