Fluid-solidified soil for embankment engineering and its filling method

Abstract

The present invention provides a fluid-solidified soil for embankment engineering and a filling method thereof, belonging to the technical field of embankment reinforcement. The fluid-solidified soil for embankment engineering comprises soil materials, cement, microbial inoculum, nutrient source, admixture and water; wherein, the weight percentage of the soil materials is 55% - 68%, the weight percentage of the cement is 10% - 16%, the weight percentage of the microbial inoculum is 1% - 2%, the weight percentage of the nutrient source is 1% - 2%, the weight percentage of the admixture is 0 - 1.0%, and the weight percentage of the water is 20% - 25%. The fluid-solidified soil provided by the present invention has high mechanical properties, high stability and corrosion resistance, can realize the ecological solidification of embankment soil bodies, significantly improve the mechanical properties and stability of embankment soil bodies, and effectively control the problems of subgrade corrosion and differential settlement.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to an embankment reinforcement material, and particularly to a fluidized solidified soil for embankment engineering and its filling method. Background Art

[0002] With the acceleration of the urbanization process, various backfill projects are increasing day by day, including the filling of underground cavities and building foundation pits, as well as the backfill of embankment widening projects. Especially during the embankment widening process, the stability of the joint between the new and old embankments and the control of differential settlement have become key technical problems. Traditional filling methods often face problems such as environmental pollution, high costs, insufficient long-term stability, complex construction processes, unstable quality, easy roadbed settlement, and the need for multiple compactions during construction, resulting in a long construction period. In addition, most of the cementitious materials in the backfill materials are mainly cement, which not only consumes a large amount of energy and natural resources, but also releases a large amount of carbon dioxide, significantly increasing greenhouse gas emissions, and is not conducive to achieving sustainable development and the effective utilization of resources; and it also requires a long time for consolidation curing, with a long construction period, seriously affecting the restoration of the widened road to its normal traffic function. Therefore, traditional embankment filling materials (also known as embankment reinforcement materials) have had a relatively serious negative impact on environmental and resource protection. Summary of the Invention

[0003] In view of this, in order to at least partially solve the above-mentioned technical problems, the present invention provides a fluidized solidified soil for embankment engineering and its filling method.

[0004] According to an embodiment of one aspect of the present invention, there is provided a fluidized solidified soil for embankment engineering, including soil materials, cement, microbial agents, nutrient sources, admixtures, and water; wherein, the weight percentage of the soil materials is 55% - 68%, the weight percentage of the cement is 10% - 16%, the weight percentage of the microbial agents is 1% - 2%, the weight percentage of the nutrient sources is 1% - 2%, the weight percentage of the admixtures is 0 - 1.0%, and the weight percentage of the water is 20% - 25%.

[0005] According to an embodiment of another aspect of the present invention, there is provided a filling method for using the above-mentioned fluidized solidified soil to reinforce an embankment, including:

[0006] Installing a retaining wall on the outside of the embankment to be widened to form a pouring space between the embankment to be widened and the retaining wall; pouring the fluidized solidified soil into the pouring space in layers and compacting it to form a fluidized solidified soil layer; and covering a moisture-proof material on the fluidized solidified soil layer formed in the pouring space to cure the fluidized solidified soil layer.

[0007] According to the fluidized solidified soil applied to embankment engineering provided in the above embodiments of the present invention, the properties of the fluidized solidified soil are improved by inducing the precipitation of silicate and calcium carbonate by microorganisms, so that the fluidized solidified soil has high mechanical properties, high stability and corrosion resistance, can realize the ecological solidification of embankment soil, significantly improve the mechanical properties and stability of embankment soil, and effectively control the problems of subgrade corrosion and differential settlement. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention and do not limit the present invention.

[0009] Figure 1 Schematic diagram of the fluidized solidified soil provided by the embodiment of the present invention for embankment engineering;

[0010] Figure 2 Flow chart of the filling method of the fluidized solidified soil provided by the embodiment of the present invention for embankment engineering;

[0011] Description of the reference numerals in the drawings:

[0012] 1 - Foundation;

[0013] 2 - Embankment to be widened;

[0014] 3 - Retaining wall;

[0015] 4 - Fluidized solidified soil layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] In order to make the purpose, technical solutions and advantages of the present invention clearer and more understandable, the following will further describe the present invention in detail with reference to specific embodiments and the accompanying drawings. However, the present invention can be implemented in different forms and should not be construed as limited to the embodiments presented herein. On the contrary, providing these embodiments will make the invention complete and thorough, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated, and the same reference numerals denote the same elements throughout.

[0017] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0018] The flowing filling material is formed by using engineering soil materials, environment-friendly composite cementitious agents and other reinforcing agents, forming a filling material with certain fluidity and mechanical properties, which has the characteristics of self-compaction, rapid construction, wide application range and environmental friendliness, and can be applied to embankment widening and reinforcement projects of various environments and grades. Microbial metabolism induces the precipitation of calcium carbonate and silicate in the soil, which can significantly enhance the shear strength, bearing capacity and long-term stability of the widened soil mass. Moreover, a large amount of carbon is contained in the precipitate generated by microbial metabolism, which can effectively sequester carbon in the soil and reduce carbon emissions. In addition, the generated consolidation layer can effectively reduce the penetration of water or pollutants. Therefore, the combination of microbial metabolism-induced soil precipitation technology and flowing filling material provides an innovative solution for embankment widening.

[0019] In view of this, it is urgent to develop an enhanced flowing solidified soil embankment reinforcement material based on bio-induced precipitation technology. The present invention provides a flowing solidified soil applied to embankment engineering. This material can give full play to the advantages of flowing filling material and bio-induced precipitation technology, significantly improve the mechanical properties and stability of the flowing solidified soil-filled embankment, and have good corrosion resistance. The embankment filled with this enhanced flowing solidified soil reinforcement material has less settlement, significantly reduces the differential settlement with the existing embankment, and ensures the integrity of the road surface. Moreover, the number of rolling times required during the construction process is less, significantly improving the construction efficiency, and having significant social and economic benefits. In addition, it is also necessary to determine an applicable construction method for this material in the embankment widening project.

[0020] According to an exemplary embodiment of the present invention, the present invention provides a flowing solidified soil applied to embankment engineering. The flowing solidified soil includes soil material, cement, microbial agent, nutrient source, admixture and water. Among them, the weight percentage of the soil material is 55% - 68%, the weight percentage of the cement is 10% - 16%, the weight percentage of the microbial agent is 1% - 2%, the weight percentage of the nutrient source is 1% - 2%, the weight percentage of the admixture is 0 - 1.0%, and the weight percentage of the water is 20% - 25%.

[0021] It should be noted that the water in the fluid solidified soil only needs to ensure the fluidity and workability of the flowing solidified soil.

[0022] In some embodiments, the soil material is clay and / or silt with cohesiveness and plasticity.

[0023] In some embodiments, the cement is PO42.5R Portland cement with a relatively fast setting and hardening speed.

[0024] In some embodiments, the nutrient source includes urea (CO(NH 2 ) 2 )、potassium dihydrogen phosphate (KH 2 PO4 ), and sodium silicate (Na 2 SiO 3 ), where urea is used as the main carbon source and potassium dihydrogen phosphate is used as the phosphorus source; among them, the molar ratio of urea to sodium silicate is 0.9 to 1.1, and the molar ratio can be, for example, 0.9, 1.0, 1.1, but is not limited to the listed values. By controlling the molar ratio of urea to sodium silicate to be 0.9 to 1.1, the growth of microorganisms in the fluidized solidified soil can be maintained, avoiding the inhibition of microorganism growth caused by excessive single element, which is beneficial to promoting the embankment reinforcement process and meeting the requirements of improving soil strength and stability.

[0025] In some embodiments, the molar ratio of urea to potassium dihydrogen phosphate is 1.0 to 2.0, and the molar ratio can be, for example, 1.0, 1.2, 1.5, 1.8, 2.0, but is not limited to the listed values. By controlling the molar ratio of urea to potassium dihydrogen phosphate to be 1.0 to 2.0, the inhibition of microorganism growth caused by too large a difference in the content of urea and potassium dihydrogen phosphate can be avoided, which is beneficial to promoting the embankment reinforcement process.

[0026] In some embodiments, the microbial inoculum includes Priestia aryabhattai, which can tolerate a salt concentration of 7% and can grow normally in an environment with a pH of 5.0 to 9.0. Priestia aryabhattai is a highly efficient silicon-solubilizing bacterium that can effectively induce the precipitation of silicate; and Priestia aryabhattai also has the function of dissolving phosphate, and can promote the improvement of soil aggregate stability and stabilize the water-stable structure of soil aggregates in saline soil.

[0027] According to the embodiments of the present invention, the enzyme in Priestia aryabhattai generates silicate precipitation and forms an anti-corrosion layer through reaction steps S01 to S03, specifically:

[0028] Step S01, Priestia aryabhattai produces urease;

[0029] Step S02, the urea in the nutrient source reacts and decomposes with water under the action of urease, and the reaction formula is as shown in formula (1):

[0030] (1);

[0031] Step S03, the ammonia and carbonate ions generated by decomposition react with the silicate minerals in the fluidized solidified soil to generate silicate precipitation, as shown in formula (2):

[0032] (2);

[0033] The overall chemical reaction formula is as follows, where is silicate precipitation, , including various different forms of hydrated silicates, as shown in formula (3):

[0034] (3).

[0035] According to an embodiment of the present invention, urea in the nutrient source can achieve soil layer stability by hydrolyzing and calcifying into calcium carbonate. Specifically, calcium carbonate precipitates at the contacts between soil particles and in the pore spaces, thereby binding the particles together and filling the inter-particle voids, improving soil properties, including increasing the strength and stiffness of the soil and reducing permeability. The specific reaction of urea hydrolyzing and calcifying into calcium carbonate includes steps S10 to S40.

[0036] Step S10, urea hydrolyzes to produce ammonia and carbamic acid, thereby increasing the pH value of the fluid-solidified soil, as shown in formula (4);

[0037] (4);

[0038] Step S20, carbamic acid further hydrolyzes into ammonia and carbonic acid, as shown in formula (5);

[0039] (5);

[0040] Step S30, ammonia further reacts to continue generating ammonium ions, carbonate ions and hydroxide ions, which further increases the pH value of the fluid-solidified soil, as shown in formula (6) and formula (7);

[0041] (6);

[0042] (7);

[0043] Step S40, when supersaturation is reached, the reaction between carbonate ions and calcium ions in the fluid-solidified soil mixture will cause calcium carbonate precipitation, as shown in formula (8);

[0044] (8).

[0045] According to an embodiment of the present invention, the mass ratio of the microbial inoculant to the nutrient source is 0.9 to 1.1. For example, it can be 0.9, 1.0, 1.1, but is not limited to the listed values. By adjusting the ratio of the microbial inoculant to the nutrient source to 0.9 to 1.1, after a series of chemical reactions, calcium carbonate precipitation and silicate precipitation are generated and an anti-corrosion layer is formed to achieve ecological reinforcement of the embankment soil body, significantly improving the mechanical properties and stability of the soil body, effectively controlling the problems of subgrade corrosion and differential settlement, and also having the advantages of environmental protection and simple construction. Specifically, the calcium carbonate precipitation and silicate precipitation effectively fill the pores of the newly built embankment, reducing the settlement of the newly built embankment after it is put into use and reducing the settlement difference with the original embankment, and can effectively control the differential settlement between the new and old embankments.

[0046] In some embodiments, the admixture includes a pH regulator, a stabilizer, and a water retention agent; wherein, the weight percentage of the pH regulator in the admixture is any value in the range of 20% to 30%, for example, it can be 20%, 24%, 25%, 28%, 30%, but is not limited to the listed values; the weight percentage of the stabilizer in the admixture is any value in the range of 40% to 60%, for example, it can be 40%, 45%, 50%, 55%, 60%, but is not limited to the listed values; the weight percentage of the water retention agent in the admixture is any value in the range of 10% to 20%, for example, it can be 10%, 12%, 14%, 18%, 20%, but is not limited to the listed values.

[0047] According to an embodiment of the present invention, the admixture is suitable for improving the physical and chemical environment of the fluidized solidified soil to ensure the normal survival of the microbial inoculant and the smooth progress of the chemical reaction.

[0048] In some embodiments, the pH regulator is selected from one or more of calcium hydroxide (Ca(OH) 2 ), sulfur (S), and aluminum sulfate (Al 2 (SO 4 ) 3 ), and is preferably calcium hydroxide (Ca(OH) 2 ). Since Priestia aryabhattai can tolerate a salt concentration of 7% and can grow normally in an environment with a pH of 5.0 to 9.0, the pH of the fluidized solidified soil is adjusted to 5.0 to 9.0 using the pH regulator, enabling Priestia aryabhattai to grow normally.

[0049] In some embodiments, the stabilizer is selected from one or more of lime, fly ash, and organic polymers, and is preferably fly ash.

[0050] In some embodiments, the water retention agent is preferably carboxymethyl cellulose (CMC) or diatomaceous earth.

[0051] According to an embodiment of the present invention, the present invention provides a reinforcing material that utilizes a specific microorganism-induced silicate precipitation technology to improve the long-term corrosion resistance and stability of fluidized solidified soil to meet the requirements of widened embankments. The fluidized solidified soil is prepared from engineering soil materials, microbial agents, nutrient sources, admixtures, construction water, etc. Admixtures are used to improve the workability of the fluidized solidified soil, pH regulators are used to control the acid-base environment of the mixed system to promote the normal reproduction and survival of microbial agents, water retention agents ensure the smooth progress of the precipitation reaction, and stabilizers improve the structure and physical properties of the soil, increasing the compressive strength and stability of the embankment after filling. Using Na 2 SiO 3 , Ca(OH) 2 and CO(NH 2 ) 2 to react to generate calcium carbonate, silicate precipitation and form an anti-corrosion layer, so that the fluidized solidified soil applied to the embankment project has good workability, mechanical properties, long-term corrosion resistance and stability.

[0052] The fluidized solidified soil provided by the present invention meets the relevant performance requirements such as the "Technical Standard for Filling with Premixed Fluidized Solidified Soil" (T / CECS1037-2022), the "Technical Standard for Engineering Application of Premixed Fluidized Solidified Soil" (DBJ51 / T188-2022), and the "Technical Specification for Filling with Premixed Fluidized Solidified Soil" (DB1310 / T298-2023), etc., and has significant social, economic and environmental benefits.

[0053] Figure 1 FIG. is a schematic diagram of the fluidized solidified soil provided by the embodiment of the present invention for use in an embankment project.

[0054] Figure 2 FIG. is a schematic flow chart of the filling method of the fluidized solidified soil provided by the embodiment of the present invention for use in an embankment project.

[0055] According to an exemplary embodiment of the present invention, the present invention provides a filling method of fluidized solidified soil for an embankment project. Referring to Figure 1 , Figure 2 shown, it includes operations S1 to S3.

[0056] Operation S1, install a retaining wall on the outside of the embankment to be widened to form a pouring space between the embankment to be widened and the retaining wall.

[0057] According to an embodiment of the present invention, before strengthening the embankment to be widened, conduct geological and soil surveys on the embankment to be widened, and based on the geology and soil quality of the embankment to be widened, determine the weight percentages of the components in the fluidized solidified soil.

[0058] In an embodiment of the present invention, according to the strength requirements of the newly built embankment, the cohesiveness of the soil, the fluidity conditions of the fluidized solidified soil, etc., the ratios of soil materials, cement, and water are determined; according to environmental factors, such as the acidity and alkalinity of the soil materials, the cement content, etc., the configuration ratios of the admixtures are determined; combining the above overall factors, the percentages of microbial agents and nutrient sources are comprehensively determined.

[0059] According to an embodiment of the present invention, before strengthening the embankment to be widened, the water content of the embankment to be widened is adjusted to the optimal construction state.

[0060] In an embodiment of the present invention, the on-site soil is taken and tested through a standard compaction test to obtain a water content relationship curve, and the peak point is taken as the optimal water content.

[0061] When the water content is too low, there is a lack of lubrication between the particles in the soil, making compaction difficult. When the water content is moderate, water acts as a lubricant, causing the soil particles to be arranged more closely, reaching the maximum dry density. When the water content is too high, too much water will cause the pores to become larger, instead reducing the density.

[0062] According to an embodiment of the present invention, before adjusting the water content of the embankment to be widened, the soil in the area of the embankment to be widened is loosened to remove stones and other impurities in the soil.

[0063] According to an embodiment of the present invention, with reference to Figure 1 As shown, a retaining wall 3 is applied to at least one side of the embankment 2 to be widened, so as to form a pouring space between the foundation 1, the embankment 2 to be widened and the retaining wall 3. Among them, applying the retaining wall 3 to at least one side of the embankment 2 to be widened includes performing base reinforcement before construction, tying steel bars, supporting formwork, and pouring concrete according to the design plan, and removing the formwork and performing quality inspection of the retaining wall after 7 days of curing. The earthwork is backfilled and compacted in layers before and after the retaining wall according to the design requirements, and the thickness of each layer is generally not more than 30 cm, and the backfill of the soil layer behind the wall is filled to the same height as the original roadbed.

[0064] In some embodiments, the retaining wall 3 is a gravity retaining wall. Through the quality inspection of the retaining wall 3, the unconfined compressive strength (7-day unconfined compressive strength) after 7 days of curing reaches 21 - 25 MPa.

[0065] Operation S2, the fluidized solidified soil is poured into the pouring space in layers and compacted to form a fluidized solidified soil layer 4.

[0066] According to an embodiment of the present invention, preparing the fluidized solidified soil includes preparing soil materials, cement, and water; preparing nutrient sources; preparing admixtures; preliminarily mixing the soil materials and cement with water, and sequentially adding microbial agents, nutrient sources, and admixtures to the mixture, and uniformly mixing to obtain the fluidized solidified soil.

[0067] According to an embodiment of the present invention, preparing the soil material includes pre-treating the soil material used for the fluidized solidified soil to remove sundries (such as plants and stones) therein.

[0068] According to an embodiment of the present invention, preparing the nutrient source includes fully mixing urea, potassium dihydrogen phosphate, and sodium silicate in a preset ratio to obtain the nutrient source.

[0069] According to an embodiment of the present invention, preparing the admixture includes fully mixing a pH regulator, a stabilizer, and a water retention agent in a preset ratio to obtain the admixture.

[0070] In some embodiments, pouring the fluidized solidified soil into the pouring space in layers can ensure that each layer of the poured fluidized solidified soil is evenly filled in the pouring space. The compaction thickness of each layer of the fluidized solidified soil during the process of pouring the fluidized solidified soil into the pouring space in layers and compacting is less than or equal to 30 cm.

[0071] Operation S3: Cover the fluidized solidified soil layer formed in the pouring space with a moisture preservation material to cure the fluidized solidified soil layer.

[0072] According to an embodiment of the present invention, after the fluidized solidified soil layer is formed, cover the fluidized solidified soil layer with a moisture preservation material, keep the suitable temperature at 25 - 30 °C, promote the growth of microorganisms, ensure the activity of enzymes, accelerate the formation of silicate precipitation, and form an anti-corrosion layer.

[0073] In some embodiments, the moisture preservation material includes geotextile or plastic film.

[0074] In some embodiments, the curing time of the fluidized solidified soil can be, for example, 7 days.

[0075] According to an embodiment of the present invention, after the end of the curing period, test the indexes such as unconfined compressive strength, permeability, stability, and anti-corrosion performance of the reinforced embankment soil mass.

[0076] According to an embodiment of the present invention, the unconfined compressive strength (7-day unconfined compressive strength) of the fluidized solidified soil layer after 7 days of curing reaches 1.5 MPa - 2.0 MPa.

[0077] According to an embodiment of the present invention, the fluidized solidified soil provided by the present invention is applicable to subgrade widening, reinforcement, and filling projects in various complex areas such as saline soil areas, soft soil areas, earthquake-active areas, and heavy traffic sections; this fluidized solidified soil is also applicable to the application of subgrade reinforcement and filling projects for various levels of roads such as expressways, first-class highways, and substandard highways.

[0078] According to an embodiment of the present invention, through the microbial-induced silicate precipitation technology, the mechanical properties and stability of the fluidized solidified soil are significantly improved.

[0079] According to an embodiment of the present invention, the fluid-solidified soil provided by the present invention can improve the stability of the embankment. Specifically, through the action of microorganisms, silicate precipitates form an enhanced cementation network inside the soil mass, making the binding between soil particles tighter, significantly increasing the unconfined compressive strength of the soil mass, greatly enhancing the stability and bearing capacity of the embankment, enabling it to better withstand various external forces, and reducing the possibility of deformation and damage.

[0080] According to an embodiment of the present invention, the fluid-solidified soil provided by the present invention can control the differential settlement between the new and old embankments. Specifically, calcium carbonate precipitation and silicate precipitation effectively fill the pores of the newly built embankment, reducing the settlement of the newly built embankment after it is put into use and the settlement difference from the original embankment, effectively controlling the differential settlement. This not only improves the flatness of the embankment but also reduces the risk of pavement cracking and damage caused by settlement differences, extending the service life of the pavement.

[0081] According to an embodiment of the present invention, the fluid-solidified soil provided by the present invention can improve the long-term stability of the embankment. Specifically, the silicate precipitates formed through microbial mineralization have excellent chemical and physical stability and can maintain their strength and stability during long-term use. This long-term stability enables the embankment to maintain a high durability when facing harsh natural conditions (such as long-term rain erosion and temperature changes) and is suitable for application in high-load transportation facilities.

[0082] According to an embodiment of the present invention, the fluid-solidified soil provided by the present invention has the advantage of being environmentally friendly. Specifically, microbial agents and biodegradable nutrient sources are used throughout the process, not only effectively reducing the use of chemical materials but also reducing environmental pollution. Compared with traditional soil filling methods, the microbial-induced method is more environmentally friendly and sustainable, helping to reduce the negative impact of the project on the surrounding ecosystem.

[0083] According to an embodiment of the present invention, the fluid-solidified soil provided by the present invention has corrosion resistance. Specifically, through the reinforcement of silicate precipitation, the corrosion resistance of the embankment has been significantly improved. The silicate precipitates form a protective layer in the soil mass, which can effectively prevent the intrusion of corrosive substances and delay the deterioration process of the soil mass. This not only extends the service life of the embankment but also reduces the future maintenance and repair costs.

[0084] The following schematically illustrates the fluid-solidified soil for embankment engineering and its filling method designed. It should be noted that this example is only a specific embodiment of the present invention and does not limit the protection scope of the present invention.

[0085] Example 1

[0086] Prepare the flowing and solidified soil. The flowing and solidified soil includes soil materials, cement, microbial agents, nutrient sources, admixtures and water. Among them, the weight percentage of the soil materials is 60.4%, the weight percentage of the cement is 13.3%, the weight percentage of the microbial agents is 2%, the weight percentage of the nutrient sources is 2%, the weight percentage of the admixtures is 1%, and the weight percentage of the water is 21.3%. The soil materials are clays with good cohesiveness and plasticity. The nutrient sources include urea, potassium dihydrogen phosphate and sodium silicate. Among them, the molar ratio of urea to sodium silicate is 1:1; the molar ratio of urea to potassium dihydrogen phosphate is 1:1.4. The stabilizer is lime; the water retention agent is diatomite; the weight percentage of the pH regulator in the admixtures is 30%, the weight percentage of the stabilizer is 50%, and the weight percentage of the water retention agent is 20%, as shown in Table 1.

[0087] Table 1

[0088]

[0089] Pour the flowing and solidified soil into the pouring space formed by the embankment to be widened and the retaining wall in layers and compact it to form a flowing and solidified soil layer.

[0090] Cover the flowing and solidified soil layer formed in the pouring space with a moisture-preserving material to cure the flowing and solidified soil layer.

[0091] After the end of the curing period, test the unconfined compressive strength, fluidity, durability and other indicators of the flowing and solidified soil layer. The test results are as follows: the 7-day unconfined compressive strength is 1.88 MPa, the fluidity is 267.5 mm, and the water loss rate is 13.8%. This can show that the flowing and solidified soil layer formed after the application of the flowing and solidified soil in Example 1 to the embankment reinforcement has high strength, low water loss rate and appropriate fluidity, and can achieve the effect of rapid embankment reinforcement.

[0092] It should be noted that the fluidity can reflect the fluidity and constructability of the flowing and solidified soil. If the fluidity is too low, the fluidity of the flowing and solidified soil mixture is poor, the construction is inconvenient, and it is difficult to flow, fill and compact by itself. If the fluidity is too high, it may cause the solidified soil to stratify and bleed water, affecting the later strength and uniformity.

[0093] The water loss rate can reflect the durability of the flowing and solidified soil. If the water loss rate is too high, the porosity in the solidified soil body will increase, the internal microstructure will become loose, the strength will decrease, and the durability will be reduced. If the water loss rate is too low, the cement hydration is insufficient, the strength development is blocked, the later strength is low, and the durability of the flowing and solidified soil is affected.

[0094] Example 2

[0095] The preparation process of the fluidized solidified soil and the process of applying it to the embankment reinforcement are the same as those in Example 1. The differences are as follows: the weight percentage of the soil material in the fluidized solidified soil is 61.3%, the weight percentage of cement is 13.5%, the weight percentage of the microbial agent is 2%, the weight percentage of the nutrient source is 2%, the weight percentage of the admixture is 1%, and the weight percentage of water is 20.2%. The soil material is a powder with good stability; the molar ratio of urea to sodium silicate in the nutrient source is 1:0.8; the stabilizer is lime; the water retention agent is diatomite. The weight percentage of the pH regulator in the admixture is 18%, the weight percentage of the stabilizer is 62%, and the weight percentage of the water retention agent is 20%, as shown in Table 2.

[0096] Table 2

[0097]

[0098] The fluidized solidified soil layer formed is tested for indicators such as unconfined compressive strength, fluidity, and durability. The test results are as follows: the 7-day unconfined compressive strength is 1.93 MPa, the fluidity is 258.5 mm, and the water loss rate is 14.6%. This shows that the fluidized solidified soil layer formed after applying the fluidized solidified soil in Example 2 to the embankment reinforcement has a high unconfined compressive strength, appropriate water loss rate and fluidity, and can achieve the effect of rapid embankment reinforcement.

[0099] Example 3

[0100] The preparation process of the fluidized solidified soil and the process of applying it to the embankment reinforcement are the same as those in Example 1. The differences are as follows: the weight percentage of the soil material in the fluidized solidified soil is 65.4%, the weight percentage of cement is 11.8%, the weight percentage of the microbial agent is 1%, the weight percentage of the nutrient source is 1%, the weight percentage of the admixture is 0%; the weight percentage of water is 20.8%, as shown in Table 3 for reference.

[0101] Table 3

[0102]

[0103] The fluidized solidified soil layer is tested for indicators such as unconfined compressive strength, fluidity, and durability. The test results are as follows: the 7-day unconfined compressive strength is 1.6 MPa, the fluidity is 236.0 mm, and the water loss rate is 15.6%. This shows that the unconfined compressive strength and fluidity of the fluidized solidified soil layer formed after applying the fluidized solidified soil in Example 3 to the embankment reinforcement are lower than those in Example 1, and the water loss rate is increased, and it can basically achieve the effect of rapid embankment reinforcement.

[0104] Example 4

[0105] The preparation process of the fluidized solidified soil and the process of applying it to embankment reinforcement are the same as those in Example 1. The differences are as follows: the weight percentage of the soil material in the fluidized solidified soil is 63.07%, the weight percentage of cement is 11.35%, the weight percentage of the microbial inoculant is 1.5%, the weight percentage of the nutrient source is 1.5%, the weight percentage of the admixture is 1%; the weight percentage of water is 21.58%, as shown in Table 4.

[0106] Table 4

[0107]

[0108] The fluidized solidified soil layer is tested for indicators such as unconfined compressive strength, fluidity, and durability. The test results are as follows: the 7-day unconfined compressive strength is 1.54 MPa, the fluidity is 253.0 mm, and the water loss rate is 15.4%. This shows that the unconfined compressive strength of the fluidized solidified soil layer formed after applying the fluidized solidified soil in Example 4 to embankment reinforcement is lower than that in Examples 1-3, the water loss rate increases, and the fluidity increases. The increase in fluidity is beneficial to quickly realizing the function of embankment reinforcement in large-area spreading construction.

[0109] Example 5

[0110] The preparation process of the fluidized solidified soil and the process of applying it to embankment reinforcement are the same as those in Example 1. The differences are as follows: the weight percentage of the soil material in the fluidized solidified soil is 59.43%, the weight percentage of cement is 13.09%, the weight percentage of the microbial inoculant is 2%, the weight percentage of the nutrient source is 2%, the weight percentage of the admixture is 1%; the weight percentage of water is 22.48%, as shown in Table 5.

[0111] Table 5

[0112]

[0113] The fluidized solidified soil layer is tested for indicators such as unconfined compressive strength, fluidity, and durability. The test results are as follows: the 7-day unconfined compressive strength is 1.73 MPa, the fluidity is 291.5 mm, and the water loss rate is 14.3%. This shows that the fluidized solidified soil layer formed after applying the fluidized solidified soil in Example 5 to embankment reinforcement has a higher unconfined compressive strength, a lower water loss rate, and a larger fluidity, and can more easily reach narrow or difficult-to-pump areas to achieve rapid embankment reinforcement.

[0114] Comparative Example 1

[0115] The preparation process of the fluidized solidified soil and the process of applying it to the embankment reinforcement are the same as those in Example 1, except that the weight percentage of the soil material in the fluidized solidified soil is 54.66%, the weight percentage of cement is 6.47%, the weight percentage of the microbial inoculant is 3%, the weight percentage of the nutrient source is 3%, and the weight percentage of the admixture is 1%; the weight percentage of water is 31.87%, as shown in Table 6.

[0116] Table 6

[0117]

[0118] The fluidized solidified soil layer is tested for indexes such as unconfined compressive strength, fluidity, and durability. The test results are as follows: the 7-day unconfined compressive strength is 0.94 MPa, the fluidity is 198.0 mm, and the water loss rate is 31.6%. This shows that after the fluidized solidified soil in Comparative Example 1 is applied to the embankment reinforcement, the unconfined compressive strength is significantly reduced, the water loss rate is relatively high, and the fluidity is insufficient, resulting in a less significant embankment reinforcement effect than that in Examples 1 to 5.

[0119] Comparative Example 2

[0120] The preparation process of the fluidized solidified soil and the process of applying it to the embankment reinforcement are the same as those in Example 1, except that the weight percentage of the soil material in the fluidized solidified soil is 65.96%, the weight percentage of cement is 9.24%, the weight percentage of the microbial inoculant is 2%, the weight percentage of the nutrient source is 3%, and the weight percentage of the admixture is 1.0%; the weight percentage of water is 18.8%, as shown in Table 7.

[0121] Table 7

[0122]

[0123] The fluidized solidified soil layer is tested for indexes such as unconfined compressive strength, fluidity, and durability. The test results are as follows: the 7-day unconfined compressive strength is 0.97 MPa, the fluidity is 210.0 mm, and the water loss rate is 16.7%. This shows that after the fluidized solidified soil in Comparative Example 2 is applied to the embankment reinforcement, the unconfined compressive strength is relatively low, the water loss rate is relatively high, and the fluidity is not ideal, failing to achieve the effect of quickly reinforcing the embankment.

[0124] Comparative Example 3

[0125] The preparation process of the fluidized solidified soil and the process of applying it to the embankment reinforcement are the same as those in Example 1, except that the weight percentage of the soil material in the fluidized solidified soil is 55.7%, the weight percentage of cement is 5.62%, the weight percentage of the microbial inoculant is 1%, the weight percentage of the nutrient source is 1%, and the weight percentage of the admixture is 0.5%; the weight percentage of water is 36.18%, as shown in Table 8.

[0126] Table 8

[0127]

[0128] The unconfined compressive strength, fluidity, durability and other indicators of the fluidized solidified soil layer were detected. The test results were as follows: the 7-day unconfined compressive strength was 0.76 MPa, the fluidity was 270.0 mm, and the water loss rate was 32.2%. This indicates that the fluidized solidified soil in Comparative Example 3 has a relatively low unconfined compressive strength and a significantly high water loss rate in the fluidized solidified soil layer formed after being applied to embankment reinforcement. Although the fluidity is good, the overall performance still cannot meet the requirements of rapid embankment reinforcement.

[0129] Comparative Example 4

[0130] The preparation process of the fluidized solidified soil and the process of applying it to embankment reinforcement were the same as those in Example 1. The differences were that the weight percentage of the soil material in the fluidized solidified soil was 65.4%, the weight percentage of cement was 11.8%, the weight percentage of the microbial inoculant was 0, the weight percentage of the nutrient source was 0, the weight percentage of the admixture was 0.8%, and the weight percentage of water was 20.8%, as shown in Table 9 for reference.

[0131] Table 9

[0132]

[0133] The unconfined compressive strength, fluidity, durability and other indicators of the fluidized solidified soil layer were detected. The test results were as follows: the 7-day unconfined compressive strength was 1.17 MPa, the fluidity was 226 mm, and the water loss rate was 16.6%. This indicates that the fluidized solidified soil in Comparative Example 4 has a relatively low unconfined compressive strength and a relatively high water loss rate in the fluidized solidified soil layer formed after being applied to embankment reinforcement, and the fluidity is insufficient, resulting in a poor embankment reinforcement effect.

[0134] Comparative Example 5

[0135] The preparation process of the fluidized solidified soil and the process of applying it to embankment reinforcement were the same as those in Example 1. The differences were that the microbial inoculant and the nutrient source were not included, and the remaining materials were supplemented in equal proportions according to Example 1. The weight percentage of the soil material in the fluidized solidified soil was 62.9%, the weight percentage of cement was 13.8%, the weight percentage of the microbial inoculant was 0, the weight percentage of the nutrient source was 0, the weight percentage of the admixture was 1%, and the weight percentage of water was 22.3%, as shown in Table 10 for reference.

[0136] Table 10

[0137]

[0138] The unconfined compressive strength, fluidity, durability and other indicators of the fluidized solidified soil layer are detected. The test results are as follows: the 7-day unconfined compressive strength is 1.35 MPa, the fluidity is 258.0 mm, and the water loss rate is 14.7%. This indicates that after the fluidized solidified soil of Comparative Example 5 is applied to embankment reinforcement, the enhancement effect of the microbial inoculant is lacking, and the unconfined compressive strength is relatively low. Although the water loss rate and fluidity are still good, the overall performance is still insufficient compared with the fluidized solidified soil of the present invention.

[0139] The test results of the above-mentioned examples and comparative examples are described as follows, as shown in Table 11 for reference:

[0140] Table 11

[0141]

[0142] According to the above-mentioned examples and comparative examples of the present invention, by regulating the proportion of each raw material in the fluidized solidified soil, a fluidized solidified soil layer with high strength, appropriate fluidity and low water loss rate can be obtained, and the ecological solidification of the embankment soil can be realized.

[0143] Among them, compared with Comparative Examples 1 to 3, the raw material ratios used in Examples 1 to 5 have significantly improved the strength of the prepared fluidized solidified soil layer, significantly reduced the water loss rate, and the fluidity is equivalent or improved, which can effectively realize the ecological solidification of the embankment soil.

[0144] Compared with Comparative Example 4, the raw materials of Examples 1 to 5 contain microbial inoculants and nutrient solutions. The strength of the fluidized solidified soil formed by Examples 1 to 5 has been significantly improved, the water loss rate has been reduced, and the fluidity has been significantly improved, which can effectively realize the ecological solidification of the embankment soil.

[0145] It is worth mentioning that the 7-day unconfined compressive strength of the fluidized solidified soil layer of Example 2 reaches 1.93 MPa. The fluidized solidified soil layer of Example 2 has appropriate fluidity and water loss rate, and better strength, and has a better effect for embankment reinforcement.

[0146] The above-mentioned specific embodiments have further detailed the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above-mentioned are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fluidized solidified soil for embankment engineering, characterized in that: Including soil, cement, microbial agents, nutrient sources, admixtures and water; Among them, the weight percentage of soil material is 55%~68%, the weight percentage of cement is 10%~16%, the weight percentage of microbial agent is 1%~2%, the weight percentage of nutrient source is 1%~2%, the weight percentage of admixture is 0~1.0%, and the weight percentage of water is 20%~25%; The microbial agent includes Priesteria agrochemicals, which is suitable for inducing silicate minerals in soil materials to react to generate silicate precipitation, and dissolving phosphates in soil materials; The nutrient sources include urea, potassium dihydrogen phosphate and sodium silicate; Among them, the molar ratio of urea to sodium silicate is 0.9~1.1, and the molar ratio of urea to potassium dihydrogen phosphate is 1.0~2.

0.

2. The fluidized solidified soil according to claim 1, characterized in that: The soil material is clay and / or silt with cohesiveness and plasticity.

3. The fluidized solidified soil according to claim 1, characterized in that: The cement is PO42.5R silicate cement.

4. The fluidized solidified soil according to claim 1, characterized in that: The additives include a pH regulator, a stabilizer and a water retaining agent; Among them, the weight percentage of the pH adjuster in the admixture is 20% to 30%, the weight percentage of the stabilizer is 40% to 60%, and the weight percentage of the water retaining agent is 10% to 20%.

5. The fluidized solidified soil according to claim 1, characterized in that: The ratio of the mass of the microbial agent to the mass of the nutrient source is 0.8-1.

2.

6. A method for filling embankment engineering using fluidized solidified soil as claimed in any one of claims 1 to 5, characterized in that: include: Installing a retaining wall outside the embankment to be widened to form a casting space between the embankment to be widened and the retaining wall; pouring the fluidized solidified soil into the pouring space in layers and compacting it to form a fluidized solidified soil layer; as well as The fluidized solidified soil layer formed in the pouring space is covered with a moisture retaining material to maintain the fluidized solidified soil layer.

7. The filling method according to claim 6, characterized in that: The fluidized solidified soil is poured into the pouring space in layers and compacted to a thickness of less than or equal to 30 cm for each layer of the fluidized solidified soil.

8. The filling method according to claim 6, characterized in that: The temperature for curing the fluidized solidified soil layer is 25℃~30℃.

9. The filling method according to claim 6, characterized in that: The unconfined compressive strength of the fluidized solidified soil layer reaches 1.5MPa~2.0MPa.

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