A construction method for protecting a siltstone slope based on a biomineralization technology

Abstract

The application provides a construction method for protecting a sinter slope based on a biological mineralization technology, comprising the following steps: S1, sinter treatment; S2, laying a plant fiber felt cloth on the sinter slope treated in the step S1; S3, spraying an A liquid of a biological curing agent with a mineralization function on the plant fiber felt cloth laid in the step S2; S4, laying a flexible geotextile cloth on the plant fiber felt cloth after the spraying in the step S3 and fixing the flexible geotextile cloth; and S5, spraying a B liquid of the biological curing agent on the flexible geotextile cloth laid in the step S4. Compared with a traditional consolidation method of inducing calcium carbonate precipitation by using microorganisms, the construction method for protecting the sinter slope based on the biological mineralization technology uses the plant fiber felt cloth to release the biological curing agent, and uses the flexible geotextile cloth to keep warm and moist, so that a better mineralization environment is created for the continuous biological mineralization, the mineralization effect and the protection function are improved, and on the other hand, the rock surface of the sinter slope is prevented from collapsing and dispersing due to the water invasion during the construction.

Description

TECHNICAL FIELD

[0001] The present application relates to a construction method for protecting a sintered sandstone slope, in particular to a construction method for protecting a sintered sandstone slope based on a biological mineralization technology. BACKGROUND

[0002] Sintered sandstone contains a large amount of montmorillonite mineral that expands significantly after absorbing water, has a significant disintegration property when encountering water, and is easily weathered under environmental erosion, exhibiting the undesirable engineering properties of "turning into sand when encountering wind and turning into mud when encountering water". In particular, sintered sandstone slopes formed by natural formation and artificial excavation are more susceptible to erosion by rainwater, resulting in a large amount of mudslides. Research on sintered sandstone slope protection technology has been ongoing, and the more mature methods currently available include cement slurry and chemical slurry. Previous research has improved chemical slurry to reduce environmental pollution in the original soil area after the application of slurry. For example, Patent No. CN112892468A discloses a modified sintered sandstone and its preparation and application method. To reduce the negative electrical property of sintered sandstone, an aluminum modification method is introduced to reduce the negative electrical property of sintered sandstone, thereby increasing the phosphorus adsorption capacity of sintered sandstone. The application of aluminum-modified sintered sandstone can achieve resource utilization of sintered sandstone, reducing the problem of phosphorus eutrophication in water bodies and the problem of low utilization of phosphorus in farmland. Vegetation planting is recognized as a green and environmentally friendly method for sintered sandstone sand fixation, such as Patent No. CN108343047B, which discloses a sintered sandstone sand barrier sand fixation method. The sintered sandstone sand barrier sand fixation method solves the problems of poor sand fixation effect, small sand fixation area, high sand barrier cost, large environmental pollution, and poor plant growth of existing sand fixation sand barriers. The sintered sandstone sand barrier designed in the invention uses local materials, saves cost, has good sand fixation effect at each stage of use, is friendly to the environment, has no pollution, is simple and easy to implement, and can be implemented on a large scale. The above innovative methods for sintered sandstone erosion prevention can achieve certain improvement effect, but the cost is increased, and the performance of pure chemical skin is unstable and easily damaged, affecting the local landscape, the types of vegetation suitable for growth are less, and the maintenance of the effect is difficult to guarantee. The method that is effective and meets the green ecological and environmental protection concept is the one that is recommended.

[0003] Biomineralization refers to the process of generating inorganic minerals by organisms through the regulation of biological macromolecules. The biggest difference from general mineralization is the participation of biological macromolecules, organism metabolism, cells and organic matrix. The role of biomineralization is that organisms convert ions in solution into solid minerals under certain physical and chemical conditions, under the control or influence of biological organic matter. Among them, microbial induced mineralization has been widely used, which can be used for sand consolidation and sand fixation. Through research, the migration of desert sand and soil can be organized by using microbial induced mineralization, for example, the patent with publication number CN110725299A discloses a method for reinforcing calcareous sand and desert sand by using a new type of microbial mineralization carbonate cementing material, and proposes that carbon-fixing bacteria are used in the cementation reaction to finally generate biological carbonate cement to achieve the reinforcement effect. Existing research has proved that it is feasible to apply biomineralization to the protection of slope surface, for example, the patent with publication number CN109576193A discloses a microbial repair liquid and its application method in the protection of sandy foundation pit slope, and proposes that the microbial liquid with mineralization function is used to realize biomineralization, which can effectively reinforce the sandy slope formed by artificial excavation, and a new type of foundation pit enclosure form is invented.

[0004] The application of green and environmentally friendly biomineralization in the reinforcement and protection of the slope of the calcareous sandstone is the popularization of the traditional microbial solidification technology in the application of the soil and rock matrix rich in fine particles. However, due to the disintegration characteristics of calcareous sandstone itself when it comes into contact with water, it is challenging to use liquid protection methods. In addition, since biomineralization relies on water as a medium to fully and effectively carry out the mineralization process, it is also difficult to ensure the humidity of the protected slope rock. In view of the above problems, the present application improves the construction method of the traditional microbial solidification technology, and realizes the protection of the slope of the calcareous sandstone by using felt and geotextile to assist the mineralization. SUMMARY

[0005] The method of the present application is aimed at the application and improvement of the biological solidification technology, overcomes the technical problems that the surface of the disintegration calcareous sandstone is easily eroded and damaged by water and it is difficult to maintain high humidity on site, and proposes a construction method for protecting the slope of the calcareous sandstone based on the biomineralization technology.

[0006] In order to achieve the above purpose, the technical scheme of the present application is as follows:

[0007] A construction method for protecting the slope of the calcareous sandstone based on the biomineralization technology, comprising the following construction steps:

[0008] S1, treating the calcareous sandstone;

[0009] S2, laying a plant fiber felt on the calcareous sandstone slope treated in step S1;

[0010] S3, spraying the plant fiber felt laid in step S2 with A liquid of the biological curing agent with mineralization function;

[0011] S4, laying and fixing flexible geotextile on the plant fiber felt sprayed in step S3;

[0012] S5, spraying the flexible geotextile laid in step S4 with B liquid of the biological curing agent;

[0013] The A liquid of the biological curing agent is a bacteria liquid with mineralization function, and the B liquid of the biological curing agent is a medicine solution containing raw materials required for biological mineralization reaction, including 5 g / L nutrient broth, 0.5 mol / L urea and calcium ions.

[0014] Preferably, the plant fiber felt is made of natural plant fiber, and no chemical agent is used in the process of making the plant fiber felt to ensure its natural state. The felt can be a fiber accumulation body of natural plant fiber without spinning or processing, or a cloth strip material of natural plant fiber after spinning and processing, but at least one side is in a plush state. The side in contact with the rock surface of the slope is in a plush state, and the natural plant fiber is a filamentous fiber with a diameter of not more than 50 microns directly produced by plants or after artificial processing.

[0015] Preferably, the flexible geotextile is a geotextile with flexibility and permeability.

[0016] Preferably, the A liquid of the biological curing agent is obtained by expanding Bacillus pasteurii Sarcina, and the Bacillus pasteurii Sarcina is inoculated into a liquid culture medium at an inoculation amount of 5% to obtain a bacteria liquid by shaking expansion. The composition of the liquid culture medium is: 10-30 g / L of yeast powder, 2-10 g / L of NH4SO4, 0-15.748 g / L of C4H 11 NO3, and 0-3 g / L of NiCl2 per liter of distilled water. The bacteria liquid after shaking expansion is centrifuged to remove the original culture medium, and then diluted with another fresh first liquid culture medium. The dilution is stopped when the OD 600 value of the bacteria liquid is 0.6-2.0, and the obtained bacteria liquid is the A liquid of the biological curing agent. The concentration is selected according to the density of the rock on the protected slope. The denser the rock, the weaker the liquid retention capacity, and the larger the concentration of the bacteria liquid.

[0017] Preferably, the B liquid of the biological curing agent includes 5 g / L of nutrient broth, 0.5 mol / L of urea and calcium ions. The source of calcium ions is a soluble calcium salt, and the ratio of the concentration of calcium ions to the concentration of urea is controlled to be between 1:1 and 1:4. During construction, the construction personnel determine the concentration of calcium ions according to the particle size distribution of the rock on the surface of the protected slope. The better the particle size distribution of the rock, the smaller the concentration of calcium ions.

[0018] Preferably, the step S1 is to remove the weathered soil of the original rock on the slope of the sandstone and then to perform the leveling operation.

[0019] Preferably, the step S2 comprises:

[0020] a. uniformly laying the plant fiber felt cloth on the rock surface of the slope;

[0021] b. checking the cracks and holes of the rock and ensuring that the plant fiber felt cloth is laid;

[0022] c. checking whether the laid plant fiber felt cloth is uniform and flat and ensuring the uniformity and flatness of the felt cloth.

[0023] Preferably, the step S4 comprises:

[0024] a. laying the flexible geotextile on the plant fiber felt cloth that has been sprayed with the biological curing agent to make the two layers of the membrane cloth tightly adhere to each other;

[0025] b. using nails to be driven into the rock of the slope surface, and the nails to pierce and fix the flexible geotextile on the slope surface.

[0026] Preferably, the volume of the biological curing agent A is 20-30% of the volume of the treatment area, and the volume of the treatment area is 5-10% of the surface area of the slope multiplied by the expected treatment depth.

[0027] Preferably, the volume of the biological curing agent B is 1:10-1:20 of the volume of the biological curing agent A, and the more dense the rock of the slope surface is, the smaller the volume is. After the volume is determined, the biological curing agent B is not sprayed on the slope at one time but is divided into at least 10 times, and the spraying amount of each time can be unequal. The biological curing agent B should be sprayed at least twice a day in terms of the construction time unit of day. The biological curing agent A contains a large amount of bacteria with mineralization function, and the bacteria can release urease in the process of life metabolism. When the biological curing agent B is mixed with A, the urease in A hydrolyzes the urea in B to produce carbonate ions, and the carbonate ions combine with the calcium ions in B to continuously grow calcium carbonate crystals around the bacteria, thereby sticking the soil particles together and improving the mechanical properties.

[0028] Preferably, the color of the flexible geotextile can be selected as needed, and the heat absorption capacity should be considered when the color is determined. For the area where the highest temperature is lower than 25℃, black geotextile is preferably selected.

[0029] Preferably, during the construction process, the humidity of the slope of the construction area within the depth of 0.5 cm is ensured to be more than 40%.

[0030] Beneficial effects:

[0031] 1. The construction method for protecting arsenic sandstone slopes based on biomineralization technology described in this invention ultimately forms a dense mineralized film on the slope surface, improving the slope's resistance to environmental erosion. The formed mineralized film is stable, strong, and has strong water retention. This construction method successfully extends the traditional microbial mineralization technology of sand to the engineering application of arsenic sandstone, achieving an innovation in green, eco-friendly construction technology for the consolidation of arsenic sandstone.

[0032] 2. Compared with the traditional microbial-induced calcium carbonate precipitation consolidation method, the biomineralization-based construction method for protecting arsenic sandstone slopes described in this invention uses plant fiber felt to slow-release bio-solidifying agents and flexible geotextiles for heat preservation and moisture retention. On the one hand, it creates a better mineralization environment for the continuous biomineralization process, improving the mineralization effect and protective function. On the other hand, it avoids the disintegration and collapse of the arsenic sandstone slope surface due to the intrusion of water during construction.

[0033] 3. The construction method for protecting arsenic sandstone slopes based on biomineralization technology described in this invention is simple to operate, has significant protective effects, and can be streamlined. It conforms to the concept of ecological and environmental protection and has broad application prospects. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1 A diagram of the slope of the test site;

[0036] Figure 2 Layout diagram of the field test area;

[0037] Figure 3 This is a construction diagram of Example 2;

[0038] Figure 4 The surface morphology of each experimental field is shown in the image after 0.5 hours of treatment.

[0039] Figure 5 The surface morphology of each experimental field after 144 hours of treatment;

[0040] Figure 6 Detailed images of the surface morphology of each experimental field after 144 hours of treatment;

[0041] Figure 7 This is a graph showing the change in penetration depth over treatment time.

[0042] Figure 8 This is a graph showing the change in crust density over treatment time.

[0043] Figure 9 Figure 2 is a graph showing the variation of the calcium carbonate content of the crust layer with time. DETAILED DESCRIPTION

[0044] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0045] The test sites of the following embodiments are located in the Kangbashi District in the south-central part of Ordos City, Inner Mongolia Autonomous Region. The Kangbashi District is located in a distribution area of bare phosphor sandstone, and bare phosphor sandstone in red and white colors can be seen everywhere in the district. Phosphor sandstone and aeolian sand are the most common ground landscapes in the area. The test site is a phosphor sandstone rock mass slope produced by artificial excavation, which is a cutting slope formed during the process of leveling the site for urban expansion. As shown in FIG. 1, the phosphor sandstone rock mass was not protected in time after excavation, and it turned into sand when it encountered wind and into mud when it encountered water. After being subjected to environmental erosion, the original rock disintegrated and weathered, producing a large amount of weathered soil. After being washed by water, deep and wide erosion gullies were formed on the slope, and the weathered soil particles continuously migrated onto the pedestrian road, even burying part of the road, which threatened the buildings on the other side of the road. Figure 1

[0046] The purpose of the following embodiments is to use microbial mineralization technology to prevent erosion of the bare phosphor sandstone slope. In the test site, the bare bedrock was selected and divided into test fields. Each test field has a size of 1.0 m x 0.7 m in rectangular shape. As shown in FIG. 2, there are five test fields, numbered TP1 to TP5, which are distributed on the phosphor sandstone rock mass slope and are not adjacent to each other, but are distributed on the same rock mass. Figure 2

[0047] The following embodiments use microbial mineralization technology and chemical solidification to protect the bare phosphor sandstone slope. The five test fields in the test site are as follows: TP1 is the traditional microbial mineralization technology; TP2 is the microbial mineralization technology with a felt blanket, referred to as fiber-assisted microbial mineralization technology; TP3 is the chemical method of W-OH anti-erosion promoting material; TP4 is the chemical method of sodium silicate; and TP5 is the blank control. Unlike laboratory tests, the construction method of field tests needs to be optimized. Both the biological mineralizer used in microbial mineralization technology and the chemical solidifier used in the chemical method are sprayed onto the rock mass of the phosphor sandstone slope to create a soaking environment.

[0048] Embodiment 1

[0049] This embodiment is carried out in the TP1 test field, and the construction method used is as follows:

[0050] ​​S1, dynamically monitor the ambient temperature of the construction area, combine with the weather forecast data, ensure that the minimum temperature at night on the construction day is not lower than 15℃, and the maximum temperature during the day is lower than 35℃. Remove the weathered soil of the quartz sandstone formed by the original rock on the quartz sandstone slope after environmental erosion, and then perform leveling operation to ensure that the slope surface has less pits and holes;

[0051] S2, spray the A liquid of the biological solidifying agent with mineralization function on the slope body leveled in step S1;

[0052] S3, lay and fix the flexible geotextile on the slope body on which the A liquid of the biological solidifying agent is sprayed in step S2;

[0053] a. Use steel nails to penetrate into the slope rock, and the steel nails pierce and fix the flexible geotextile on the slope surface;

[0054] S4, spray the B liquid of the biological solidifying agent on the flexible geotextile laid in step S3.

[0055] In the embodiment, the flexible geotextile is a geotextile with flexibility and permeability.

[0056] In the embodiment, the A liquid of the biological solidifying agent is prepared by expanding Sphaerotilus pauculus. The Sphaerotilus pauculus is inoculated into a liquid culture medium at an inoculation amount of 5%, and a bacterial liquid is prepared by shock expansion. The composition of the liquid culture medium is: 20 g / L of yeast powder, 10 g / L of NH4SO4, 15.748 g / L of C4H 11 NO3, 2 g / L of NiCl2 per liter of distilled water; the bacterial liquid after shock expansion is removed from the original culture medium, and then diluted with another fresh first liquid culture medium. When the OD 600 value of the bacterial liquid is 1.2, stop dilution, and the obtained bacterial liquid is the A liquid of the biological solidifying agent.

[0057] In the embodiment, the formula of the B liquid of the biological solidifying agent is: 5 g / L of nutrient broth, 5 g / L of peptone, 0.5 mol / L of urea, and 0.25 mol / L of calcium ion. The volume of the A liquid of the biological solidifying agent is: the volume of the A liquid of the biological solidifying agent is 20% of the volume of the treatment area, and the volume of the treatment area is 5% of the surface area of the slope body multiplied by the expected treatment depth of 0.5 cm. The volume of the B liquid of the biological solidifying agent is: the volume of the sprayed B liquid of the biological solidifying agent is 1:20 of the volume of the A liquid of the biological solidifying agent. After the volume is determined, the B liquid of the biological solidifying agent is sprayed for 10 times, and each time is sprayed equally. The spraying is continuously performed for 5 days, and each time is sprayed twice a day.

[0058] The microbial mineralization technology needs a certain time for chemical action to realize mineralization, so it is necessary to keep the test field with high humidity. The embodiment ensures the humidity of more than 40%; in order to keep the humidity, the flexible geotextile mentioned before is used as a shield and placed on the surface of the test field after spraying the mineralization agent, which can slow down the evaporation of water on one hand and can absorb more heat of sunlight on the other hand due to its black physical characteristics, which is beneficial to the microbial mineralization reaction and the chemical reaction of the mineralization agent.

[0059] Embodiment 2

[0060] The embodiment adopts the method of the application and is carried out in the TP2 test field. Specifically, as shown in the following table, the embodiment includes the following construction steps: Figure 3

[0061] S1, dynamically monitor the environmental temperature of the construction area, and combine the weather forecast data to ensure that the minimum temperature at night on the construction day is not lower than 15℃ and the maximum temperature during the day is lower than 35℃. Remove the weathered soil of the pisha sandstone formed after the original rock of the pisha sandstone slope is eroded by the environment, and then perform leveling work to ensure that there are fewer pits and holes on the surface of the slope body;

[0062] S2, lay the plant fiber felt with an average thickness of 5mm on the pisha sandstone slope treated in step S1;

[0063] a, uniformly lay the plant fiber felt on the rock surface of the slope body;

[0064] b, check the cracks and holes of the rock in a targeted manner to ensure that the plant fiber felt is laid;

[0065] c, check whether the laid plant fiber felt is uniform and flat to ensure the uniformity and flatness of the felt;

[0066] S3, spray the A liquid of the biological curing agent with mineralization function on the plant fiber felt laid in step S2;

[0067] S4, lay the flexible geotextile on the plant fiber felt laid in step S3 and fix it;

[0068] a, lay the flexible geotextile on the plant fiber felt on which the biological curing agent has been sprayed, and try to make the two layers of membrane cloth tightly adhere to each other;

[0069] b, use steel nails to penetrate into the rock surface of the slope, and the steel nails will pierce and fix the flexible geotextile on the slope surface;

[0070] S5, spray the B liquid of the biological curing agent on the flexible geotextile laid in step S4.

[0071] ​The plant fiber felt cloth in the embodiment is made of natural plant fiber, and no chemical agent is used in the process of making the plant fiber felt cloth, so that the natural state is ensured. The surface in contact with the rock surface of the slope body is in a plush state. The natural plant fiber is a filamentous fiber with a diameter of not greater than 50 microns after the plant is directly generated.

[0072] The flexible geotextile in the embodiment is a geotextile with flexibility and permeability.

[0073] In the embodiment, the biological curing agent A liquid is obtained by expanding Sphaerotilus pasteurii. The Sphaerotilus pasteurii is inoculated into a liquid culture medium at an inoculation amount of 5%, and then shaken and expanded to obtain a bacterial liquid. The liquid culture medium comprises 20 g / L of yeast powder, 10 g / L of NH4SO4, 15.748 g / L of C4H 11 NO3, and 2 g / L of NiCl2 per liter of distilled water. After the bacterial liquid is shaken and expanded, the original culture medium is removed, and the bacterial liquid is diluted with another fresh first liquid culture medium. When the OD 600 value of the bacterial liquid is 1.2, the dilution is stopped, and the obtained bacterial liquid is the biological curing agent A liquid.

[0074] In the embodiment, the formula of the biological curing agent B liquid is 5 g / L of nutrient broth, 5 g / L of peptone, 0.5 mol / L of urea, and 0.25 mol / L of calcium ions. The volume of the biological curing agent A liquid is 20% of the volume of the treatment area, which is 5% of the surface area of the slope body multiplied by the expected treatment depth of 0.5 cm. The volume of the biological curing agent B liquid is 1:20 of the volume of the biological curing agent A liquid. After the volume is determined, the biological curing agent B liquid is sprayed for 10 times, and each time is sprayed in equal amounts. The spraying is continuously performed for 5 days, and the spraying is performed twice a day.

[0075] The microbial mineralization technology needs a certain time for chemical action to realize mineralization, so it is necessary to keep the test field with a relatively high humidity. In the embodiment, the humidity is ensured to be more than 40%. In order to keep the humidity, the flexible geotextile mentioned above is used as a shield and placed on the surface of the test field after the mineralization agent is sprayed. On the one hand, the flexible geotextile can slow down the evaporation of water, and on the other hand, the black physical characteristics of the flexible geotextile can absorb more heat of sunlight, which is beneficial to the microbial mineralization reaction and the chemical reaction of the mineralization agent.

[0076] Embodiment 3:

[0077] The embodiment is carried out in TP3 test field, and the specific construction method is that the purchased W-OH anti-erosion promoting material curing agent is diluted 100 times according to the solute amount, the volume amount of the anti-erosion promoting material solution after dilution is 400% of the treatment area volume, and the treatment area volume is 5% of the slope surface area multiplied by the expected treatment depth of 0.5 cm. After the volume amount is determined, the biological curing agent B liquid is sprayed for 10 times, and each time is sprayed equally; the continuous spraying is carried out for 5 days, and the spraying is carried out twice a day. The W-OH anti-erosion promoting material is W-OH high-tech modified hydrophilic polyurethane composite material purchased from Jiangsu Jiecheng Kaixin New Material Technology Co., Ltd.

[0078] Embodiment 4

[0079] The embodiment is carried out in TP4 test field, and the specific construction method is that the purchased sodium silicate is dissolved into a solution according to the solute amount of 1%, the volume amount of the sodium silicate is 400% of the treatment area volume, and the treatment area volume is 5% of the slope surface area multiplied by the expected treatment depth of 0.5 cm. After the volume amount is determined, the biological curing agent B liquid is sprayed for 10 times, and each time is sprayed equally; the continuous spraying is carried out for 5 days, and the spraying is carried out twice a day.

[0080] The sodium silicate purchased is sodium silicate nine hydrate produced by National Pharmaceutical Group Chemical Reagent Co., Ltd.

[0081] Embodiment 5

[0082] The embodiment is carried out in TP5 test field, and the difference from embodiment 3 is that tap water is used instead of mineralizer.

[0083] The specific test scheme of embodiments 1-5 is shown in Table 1.

[0084] Table 1: Field test scheme

[0085]

[0086] In Table 1, the amount of bacteria solution is calculated according to the ratio of soil to bacteria, 196:40. According to the size of the test field and assuming that the effective treatment depth is 0.5 cm, 900 ml of mineralizer A solution and 18 L of mineralizer B solution are required. Since the microbial mineralization process is a continuous process and is not as rapid as a chemical reaction, the treatment time is designed to be 5 days. The bacteria solution is sprayed onto the test field at the beginning of the mineralization, and the mineralizer B solution is sprayed onto the test field in 10 equal portions over 5 days, twice a day at 12:00 and 18:00. This approach prevents the loss of mineralizer B solution due to excessive spraying at once, while ensuring the continuous progress of induced mineralization. Although both the bacteria solution and the mineralizer B solution are sprayed onto the surface, the 0.5 cm surface layer of the test field after spraying the mineralizer B solution should be in a saturated state, with continuous replenishment of the mineralizer B solution to maintain the surface layer in a near-saturated state for as long as possible, making the field test operation similar to the immersion method used in laboratory research. To ensure comparability, the amount of mineralizer used in the chemical method (Examples 3 and 4) is consistent with that of the microbial method, and the blank control test field TP5 uses tap water instead of mineralizer. The treatment process is based on the noon 12:00 of the first day as the 0th hour of treatment.

[0087] 1. Detection method

[0088] The calcium carbonate content, penetration resistance, morphological characteristics, and soil density of the surface layer of each test field at different treatment times are measured to compare the effects of different methods. Each test value is tested on three parallel points, and the average value is taken. Each test is conducted at 12:30 pm on the treatment day, when the mineralizer has just been sprayed and the surface of the test field is moist. The measured penetration resistance reflects the surface strength under the most unfavorable conditions with water. Continuous testing is conducted 5 times, starting at the 24th hour of treatment, every 24 hours, and ending at 12:00 pm on the 6th day of the test.

[0089] Since the surface layer is composed of rock, the penetration resistance will continue to increase with increasing penetration depth. The slope protection performed in this embodiment mainly forms a protective layer on the surface of the rock mass, so the improvement in strength and erosion resistance is mainly reflected in the surface layer of the rock mass. In order to compare the differences in surface layer performance between different test fields, the depth of penetration at a penetration resistance of 150 N is measured to reflect the strength of the crust.

[0090] The calcium carbonate content is still measured using the hydrochloric acid titration method, and the tested sample is the soil sample from the 0.5 cm deep area on the surface of the test field.

[0091] 2. Test results and analysis

[0092] 2.1 Analysis of changes in the surface morphology of the shihezi sandstone

[0093] The surface topography of each test plot at treatment time of 0.5 is shown in Figure 4 The surface topography of each test plot at treatment time of 144 is shown in Figure 5

[0094] From Figure 4 it can be seen that the different treatment methods have different effects on the surface of the test plot. The surface of the blank control TP5 has disintegrated and become rough after spraying with tap water; TP1 and TP2 are microbial mineralization technologies, and the surface of the top layer is covered with flexible geotextile, and TP2 uses plant fiber to stabilize the mineralization agent. It can be seen that the felt made of plant fiber is laid on the test plot, and after spraying the bacterial solution, part of the bacterial solution is adsorbed on the felt, making the felt appear yellowish wet. In TP3, W-OH is a white emulsion itself, which will quickly adhere to the rock mass when sprayed on the surface of the top layer, and in the wet state, it presents white properties. The surface of TP4 becomes dense after spraying sodium silicate solution, and although the surface of TP4 does not change much in color, it is different from TP5 in that the surface does not become rough and does not disintegrate obviously after spraying the transparent liquid. During the field test, except for TP5, the rock mass on the surface of the top layer of the other test plots did not disintegrate and fall off obviously after spraying the mineralization agent. The above treatment methods at least cause as little disturbance to the original site as possible before achieving the treatment purpose.

[0095] After 5 days of treatment, the protective crust on the surface of the top layer has basically formed, especially TP1 and TP2 using microbial mineralization technology, as no mineralization agent B is sprayed, it is considered that the induced mineralization has basically stopped. From Figure 5 it can be seen that the surface of the blank control TP5 becomes uneven due to water erosion, the surface disintegrates seriously and becomes very crumbly. Unlike TP5, the surfaces of the other test plots become dense and it is obvious that a crust has formed. During the entire treatment process, the liquid sprayed continuously does not cause serious erosion and damage to the surface of the top layer, and successfully forms a functional crust on the surface.

[0096] The Figure 5 microscopic morphology of the surface of the test plot is tested by using a microscope with a magnification of 200 times. The test results are shown in Figure 6 ​From the pictures, it can be seen that after the microbial mineralization treatment, the semi-transparent white crystals between the particles of the sandstone increase, and the TP2 has more crystals than the TP1, and the crystals have more complex shapes. These crystals fill in the connections between the particles and the gaps, and form a whole with the particles in the whole test area. Unlike the TP1 and TP2, the particles between the TP3 and TP4 using the chemical curing agent are filled with colloidal substances, and the colloidal substances of the TP3 have a yellowish color. According to the mechanism of the mineralization method used, it can be known that the semi-transparent crystals are calcium carbonate, and the yellowish and white colloidal substances are sols of W-OH and sodium silicate respectively.

[0097] The above test results prove that it is feasible to use the microbial mineralization technology to implement the protection of the sandstone slope in the field, and after the treatment of the microbial mineralization technology, the surface of the surface layer can form a dense mineralization coating filled with calcium carbonate crystals. Under the climate conditions of the field which are very uncertain, the process of the induced mineralization of the microorganisms can still be realized. The mineralization technology assisted by the plant fibers can improve the mineralization effect in the field.

[0098] 2.2 Penetration resistance

[0099] In order to quantitatively analyze the strength of the crust layer and compare the effects of different treatment methods, the penetration depths of the test fields at the penetration resistance of 150 N are listed in Table 2, and the curve is shown in Figure 7 From the picture, it can be seen that after the treatment, the penetration depth of the TP5 of the blank control at the penetration resistance of 150 N is the largest, and the penetration depths of the other test fields from large to small are TP4, TP3, TP1 and TP2. Moreover, the penetration depth of the smallest TP2 is 3 mm, and the penetration depth of the TP5 at the same period is 28 mm, and the difference between them is 9 times. Compared with the TP1, the penetration depth of the TP2 measured after the treatment is basically the same, and the penetration depth of the TP2 is slightly higher. The penetration depths of the TP1 and the TP2 are both higher than those of the TP3 and the TP4. Compared the biological method with the chemical method, the crust strength formed by the TP3 and the TP4 of the chemical method is higher than that of the TP1 and the TP2 of the biological method in the early treatment period, but the biological method gradually exceeds the chemical method in the late treatment period.

[0100] Table 2 Penetration depth changes with treatment time

[0101]

[0102] The above test results show that each treatment method makes the strength of the surface layer larger and the surface harder. The biological method is better than the chemical method, but the difference is not very large. The microbial mineralization technology assisted by the fibers has the highest mineralization effect, and the crust obtained is the hardest, and the strength of the surface layer is the highest.

[0103] 2.3 Crust density

[0104] Several treatment methods make the surface of the rock more dense, and the pores between the particles are filled with functional substances, and the pores are reduced. The density of the skin layer obtained by each treatment method is shown in Table 3, and the curve of the development of the density of the skin layer with the treatment time is shown in Figure 8

[0105] As can be seen from the figure, except for TP5 of the blank control, the density of the skin layer of the other test fields increases with the increase of the treatment time. After the treatment, the density of the skin layer of TP2 is larger than that of the other test fields at the same period, and compared with TP5, it increases by 6.2% at the same period. This is not difficult to explain. Due to the filling of the cementing material, the particles become dense, the solid material per unit volume increases, and the density of the rock becomes larger. TP2 has a continuous and stable induced mineralization reaction due to the assistance of plant fibers, and the calcium carbonate crystals between the particles increase continuously with the progress of the mineralization reaction, and the density becomes larger and larger. The skin density increases and becomes dense, which is beneficial to resist the erosion of various environments.

[0106] Table 3 Change of density of skin layer with treatment time

[0107]

[0108] 2.4 Calcium carbonate content

[0109] The effect of biological method on surface protection is better than that of chemical method. The treatment method based on microbial mineralization technology mainly relies on the calcium carbonate crystals produced by mineralization to improve the surface protection performance, therefore, from the perspective of calcium carbonate content, the mechanism of performance improvement of the skin layer is analyzed.

[0110] The calcium carbonate content of the skin layer of each test field at different treatment times is shown in Table 4, and the curve of the change of the calcium carbonate content of the skin layer with the treatment time is shown in Figure 9 As can be seen from the figure, before and after the treatment, the calcium carbonate content of the skin layer of TP3, TP4 and TP5 is almost unchanged, and even has a slight decreasing trend, while the mineralized skin layer of TP1 and TP2 of the biological method increases with the continuous increase of the treatment time, and after the treatment, the calcium carbonate content of TP2 increases to 6.73%, and the content of TP1 at the same period is only 3.47%, which is almost doubled. The change trend of the calcium carbonate content is basically similar to the development of the skin layer penetration resistance with the treatment time, which well reveals the mechanism of the improvement of the protection performance of the skin layer.

[0111] Table 4 Change of calcium carbonate content of skin layer with treatment time

[0112]

[0113] ​From the results of the above examples, it can be seen that: using chemical curing method and microbial mineralization method for treatment of the site of the sandstone slope, the penetration resistance and material properties of the cured skin layer are determined, the protection effect of the chemical curing method and the microbial mineralization method for the site treatment of the sandstone slope is compared, and the microbial mineralization method suitable for the site construction is proposed. The results show that: (1) with the help of plant fiber, the microbial mineralization technology is applied to the site protection and treatment of the sandstone slope, and the effect is remarkable. It is feasible to use microbial mineralization technology to implement the protection of the sandstone slope in the field, and the surface of the surface layer treated by the microbial mineralization technology can form a dense mineralization film filled with calcium carbonate crystals. (2) Each treatment method makes the strength of the surface layer larger and the surface harder, and the biological method is better than the chemical method, but the difference is not large. The mineralization technology assisted by plant fiber can improve the mineralization effect in the field, and the penetration depth of the microbial mineralization test field without plant fiber is 50% larger than that with plant fiber when the penetration resistance is 150N. Each treatment method makes the strength of the surface layer larger and the surface harder. The mineralization effect of the microbial mineralization technology assisted by plant fiber is the highest, the calcium carbonate content of the skin layer increases to 6.73%, the obtained skin is the hardest, and the strength of the surface layer is the highest

[0114] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A construction method for protecting a slope of a sinter rock based on a biomineralization technique, characterized by: The method comprises the following steps: S1, treating the sandstone; S2, laying the plant fiber felt cloth on the sandstone slope treated in step S1; S3, spraying the biological solidifying agent A with mineralization function on the plant fiber felt cloth laid in step S2; S4, laying the flexible geotextile on the plant fiber felt cloth sprayed in step S3 and fixing it; S5, spraying the biological solidifying agent B on the flexible geotextile laid in step S4; The biological solidifying agent A liquid is a bacteria liquid with mineralization function, the biological solidifying agent B liquid is a medicine solution containing raw materials required for biological mineralization reaction, containing urea and calcium ions; the flexible geotextile is black geotextile; the biological solidifying agent A liquid is obtained by expanding Sphaerotilus paratyphi-B, and the Sphaerotilus paratyphi-B is inoculated into liquid culture medium at an inoculation amount of 5% to be expanded by oscillation to obtain the bacteria liquid, wherein the liquid culture medium comprises 10-30 g / L of yeast powder, 2-10 g / L of NH4SO4, 0-15.748 g / L of C4H 11 NO3, 0-3 g / L of NiCl2 per liter of distilled water; the bacteria liquid after oscillation expansion is centrifuged to remove the original culture medium, and then diluted with another fresh first liquid culture medium; when the OD 600 value of the bacteria liquid is 0.6-2.0, the dilution is stopped, and the obtained bacteria liquid is the biological solidifying agent A liquid.

2. The construction method for protecting the slope of the sinter rock based on the biomineralization technology according to claim 1, characterized in that: The plant fiber felt cloth is made of natural plant fiber, and the surface in contact with the rock surface of the slope is in a plush state. The natural plant fiber is a filamentous fiber with a diameter of not more than 50 microns directly generated by plants or artificially processed.

3. The construction method for protecting the slope of the sinter rock based on the biomineralization technology according to claim 1, characterized in that: The flexible geotextile is a geotextile with flexibility and permeability.

4. The construction method for protecting the slope of the sinter rock based on the biomineralization technology according to claim 1, characterized in that: The biological solidifying agent B comprises 5 g / L of nutrient broth, 0.5 mol / L of urea and calcium ions. The source of calcium ions is a soluble calcium salt, and the ratio of the concentration of calcium ions to the concentration of urea is controlled to be between 1:1 and 1:

4.

5. The construction method for protecting the slope of the sinter rock based on the biomineralization technology according to claim 1, characterized in that: The step S1 is to remove the weathered soil of the sandstone formed after the original rock of the sandstone slope is eroded by the environment, and then perform leveling operation.

6. The construction method for protecting the slope of the sinter rock based on the biomineralization technology according to claim 1, characterized in that: The step S2 comprises: a. uniformly laying the plant fiber felt cloth on the rock surface of the slope; b. checking the cracks and holes of the rock in a targeted manner to ensure that the plant fiber felt cloth is laid; c. checking whether the laid plant fiber felt cloth is uniform and flat to ensure the uniformity and flatness of the felt cloth.

7. The construction method for protecting the slope of the sinter deposit based on the biomineralization technology according to claim 1, characterized by the fact that: The step S4 comprises: a. laying the flexible geotextile on the plant fiber felt cloth that has been sprayed with the biological solidifying agent, so that the two layers of film cloth are tightly attached; b. using nails to penetrate into the rock surface of the slope, and the nails pierce and fix the flexible geotextile on the slope surface.

8. The construction method for protecting the slope of the sinter rock based on the biomineralization technology according to claim 1, characterized in that: The volume of the biological solidifying agent A is 20-30% of the volume of the treatment area, and the volume of the treatment area is 5-10% of the surface area of the slope multiplied by the expected treatment depth.

9. The construction method for protecting the slope of the sinter rock based on the biomineralization technology according to claim 8, characterized in that: The volume of the biological solidifying agent B is 1:10-1:20 of the volume of the biological solidifying agent A, and the spraying is at least divided into 10 times.

10. The construction method for protecting the slope of the sinter deposit based on the biomineralization technology according to claim 1, characterized in that: During construction, the humidity in the slope of the construction area within 0.5 cm depth is ensured to be more than 40%.

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