阅读说明：本技术 一种联合微生物及高分子树脂快速资源化利用软土的方法 (Method for quickly recycling soft soil by combining microorganisms and high polymer resin ) 是由 华晓烨 彭劼 戴迪 徐亮 白兰兰 丁鸿志 涂圣武 赵余 曹天赐 赖用满 赵晓婉 于 2020-12-03 设计创作，主要内容包括：本发明公开了一种联合微生物及高分子树脂快速资源化利用软土的方法,涉及岩土工程领域。本方法的技术方案如下：首先将产脲酶微生物和胶结液原料配制成高浓度的悬浊液；再将吸水倍率400-800倍的高分子树脂与其混合；然后将适量上述混合物与软土拌和,快速将软土含水率降低至最优含水率+6~8%；上述混合物构成MICP反应颗粒,反应析出碳酸钙并消耗液态水进一步降低软土含水率,碳酸钙的填充作用能够显著提高土体强度。接下来将4~7%的石灰与土体拌和均匀,并作为路基材料进行摊铺,碾压成型后,土体逐渐硬化,加上石灰的固化作用,能够满足路基填筑的压实度、强度及水稳性要求。该方法不仅可充分利用工程中的开挖弃土、保护环境,而且施工速度快、简单易行。(The invention discloses a method for quickly recycling soft soil by combining microorganisms and high polymer resin, and relates to the field of geotechnical engineering. The technical scheme of the method is as follows: firstly, preparing urease-producing microorganisms and cementing liquid raw materials into high-concentration suspension; then mixing the high molecular resin with the water absorption rate of 400-800 times with the high molecular resin; then mixing a proper amount of the mixture with soft soil, and quickly reducing the water content of the soft soil to the optimal water content of + 6-8%; the mixture forms MICP reaction particles, calcium carbonate is separated out through reaction, liquid water is consumed, the water content of soft soil is further reduced, and the filling effect of the calcium carbonate can remarkably improve the soil strength. And then, uniformly mixing 4-7% of lime and a soil body, paving the mixture as a roadbed material, gradually hardening the soil body after rolling and forming, and meeting the requirements of compactness, strength and water stability of roadbed filling due to the solidification effect of the lime. The method can not only make full use of the excavated waste soil in the engineering and protect the environment, but also has fast construction speed and simple and easy operation.)

1. A method for rapidly recycling soft soil by combining microorganisms and high polymer resin is characterized by comprising the following steps:

step 1) mixing urease-producing bacteria with good activity with cementing liquid raw materials to form a microorganism + cementing material suspension with higher concentration;

step 2) selecting a proper amount of polymer resin, and stirring and mixing the polymer resin with the microorganism and the cementing material suspension to obtain a mixture of the polymer resin and the microorganism and the cementing material suspension;

step 3) fully mixing the mixture of the polymer resin, the microorganism and the cement turbid liquid with the soft soil, so that the polymer resin absorbs pore water in the soft soil, the water content of the soft soil can be rapidly reduced, and the water content of the soft soil is reduced to the optimal water content of the soft soil plus 6-8%;

step 4), the polymer resin, the microorganism and the cementing material suspension and water absorbed by the polymer resin which are mixed into the soft soil form the micro MICP reaction particles, after a certain reaction time, the microorganism and the cementing material react to generate calcium carbonate precipitates, and the filling effect of the calcium carbonate precipitates can obviously improve the strength of the micro MICP reaction particles; meanwhile, liquid water is consumed in the reaction, so that the water content of the obtained soil body is closer to the optimal water content;

step 5) mixing 4-7% of lime with the soil body obtained in the step 4) uniformly to form roadbed filling soil;

and 6) paving the roadbed filling soil on the roadbed, controlling the thickness of each layer to be 20-40 cm, and performing layered rolling forming on the paved soil body to finish the resource treatment of the soft soil.

2. The method for rapidly recycling soft soil by combining microorganisms and high polymer resins according to claim 1, which is characterized by comprising the following steps: the urease-producing bacteria in the step 1) are bacillus pasteurii; the cementing liquid comprises solid calcium chloride and urea.

3. The method for rapidly recycling soft soil by combining microorganisms and high polymer resin according to claim 2, wherein the method comprises the following steps: the concentration of calcium chloride and urea in the microorganism and cement turbid liquid with higher concentration in the step 1) is 5-8 mol/L, and the concentration of microorganisms is 2-410¹¹ CFU/L。

4. The method for rapidly recycling soft soil by combining microorganisms and high polymer resins according to claim 1, which is characterized by comprising the following steps: and 2) the high polymer resin is water-absorbent resin, and the water absorption rate of the high polymer resin is 400-800 times.

5. The method for rapidly recycling soft soil by combining microorganisms and high molecular resins according to claim 1 or 4, wherein the method comprises the following steps: the polymer resin has hydrophilic groups and a certain crosslinking degree, can keep the synthetic resin from outflow after absorbing a large amount of moisture, and can absorb moisture which is 500-2000 times of the self weight.

6. The method for rapidly recycling soft soil by combining microorganisms and high polymer resins according to claim 1, which is characterized by comprising the following steps: the mixture of the polymer resin and the microorganism + the cementing material turbid liquid in the step 2) comprises 555-888 g/L of calcium chloride, 300-480 g/L of urea and 2-4 of microorganisms10¹¹CFU/L, 60-120 g/L of polymer resin and 1000g/L of water.

7. The method for rapidly recycling soft soil by combining microorganisms and high polymer resins according to claim 1, which is characterized by comprising the following steps: the mixing proportion of the mixture of the polymer resin, the microorganism and the cement turbid liquid in the step 3) to the soft soil is 25-35L: 1000L.

8. The method for rapidly recycling soft soil by combining microorganisms and high polymer resins according to claim 1, which is characterized by comprising the following steps: the reaction time in the step 4) is 36-72 hours.

Technical Field

The invention relates to the field of geotechnical engineering, in particular to a method for quickly recycling soft soil by combining microorganisms and high polymer resin.

Background

With the continuous development of economy in China, the large-scale construction of high-grade roads is still in progress. In the road construction process of China, a lot of soft soil subgrades are often encountered, the soft soil has the characteristics of high moisture content, high content of clay particles and organic matters, low permeability coefficient and the like, and the strength and compression characteristics of the soft soil are difficult to meet the engineering requirements.

The traditional soft soil treatment method comprises a composite foundation method, a drainage consolidation method, a chemical consolidation method, a dynamic consolidation method, a replacement method and the like. A soft soil layer with small earth surface thickness (0.5-5 m thick) is usually treated by a replacement method. However, in recent years, China has increasingly strong protection on ecological environment, and the problems of shortage of soil replacement sources, no place for placing excavated waste soil and the like exist by adopting a replacement method. The solidified soil technology can improve the strength of soft soil, but under the condition that the water content of the soft soil is higher (40-60%), the requirement of roadbed filling is still difficult to meet after solidification treatment, if the water content of the soft soil is reduced to be close to the optimal water content suitable for filling, the procedures of piling, airing and the like are often required, the time consumption is long, and the soft soil needs to be repeatedly turned over and aired and is easily influenced by weather. Therefore, it is necessary to invent a method for utilizing soft soil as roadbed filling material after the soft soil is rapidly treated.

The high-molecular water-absorbent resin (SAP) is a novel high-molecular functional material, is a water swelling type high-molecular material which contains strong hydrophilic functional groups such as-COOH, -OH and the like and has higher crosslinking degree, is insoluble in water and organic solution, and has water absorption multiplying power of 500-2000 times. After absorbing water, the material is difficult to squeeze out water by using a common physical method, and can repeatedly release and absorb water, so the material is widely applied to various fields, such as baby diapers, sanitary napkins, drug slow-release materials and the like, is used as an oil-water separating agent, a drying agent, a deodorizing agent, a cable, a waterproof plugging material and the like in industry, and is used for drought resistance, water retention, pesticide and fertilizer slow release and the like in agriculture. But is not used as a dehydrating material in soft soil reinforcement because moisture remains in soil after water absorption and SAP particles have low strength after water absorption.

The basic principle of MICP reinforced soil is to inject specific microorganisms into the soil, and urease produced by the microorganisms can hydrolyze urea to produce calcium carbonate ions (CO)₃ ^2-) Post-reaction with calcium ion (Ca)²⁺) Reaction to form calcium carbonate (CaCO)₃) Crystallization, the total reaction process is as follows:

the step-by-step disassembly is as follows:

CaCl₂+H₂CO₃→CaCO₃↓+2HCl

2HCl+2NH₄OH→2NH₄Cl+2H₂O

calcium carbonate precipitates generated in the reaction are deposited among loose soil particles and play a cementing role, so that the cementing reinforcement of the soil body is realized; while the reaction requires the consumption of a certain amount of water. However, when the method is applied, microorganisms and cementing materials are generally injected, and the method is generally used for sand reinforcement treatment with a large permeability coefficient.

Disclosure of Invention

The invention aims to provide a method for quickly recycling soft soil by combining microorganisms and high-molecular resin, and the soft soil is quickly recycled by combining a technology of reinforcing soil by microorganism induced calcium carbonate deposition (MICP) and an SAP (super absorbent polymer) material.

The technical solution for realizing the purpose of the invention is as follows: a method for quickly recycling soft soil by combining microorganisms and high polymer resin comprises the following steps:

step 1) mixing urease-producing bacteria with good activity with cementing liquid raw materials to form a microorganism + cementing material suspension with higher concentration;

step 2) selecting a proper amount of polymer resin, and stirring and mixing the polymer resin with the microorganism and the cementing material suspension to obtain a mixture of the polymer resin and the microorganism and the cementing material suspension;

step 3) fully mixing the mixture of the polymer resin, the microorganism and the cement turbid liquid with the soft soil, so that the polymer resin absorbs pore water in the soft soil, the water content of the soft soil can be rapidly reduced, and the water content of the soft soil is reduced to the optimal water content of the soft soil plus 6-8%;

step 4), the polymer resin, the microorganism and the cementing material suspension and water absorbed by the polymer resin which are mixed into the soft soil form the micro MICP reaction particles, after a certain reaction time, the microorganism and the cementing material react to generate calcium carbonate precipitates, and the filling effect of the calcium carbonate precipitates can obviously improve the strength of the micro MICP reaction particles; meanwhile, liquid water is consumed in the reaction, so that the water content of the obtained soil body is closer to the optimal water content;

step 5) mixing 4-7% of lime with the soil body obtained in the step 4) uniformly to form roadbed filling soil;

and 6) paving the roadbed filling soil on the roadbed, controlling the thickness of each layer to be 20-40 cm, and performing layered rolling forming on the paved soil body to finish the resource treatment of the soft soil.

Compared with the prior art, the invention has the remarkable advantages that: the water content of the soft soil can be quickly reduced by absorbing hundreds of times of liquid water by using the polymer resin, and then calcium carbonate precipitates are generated by the reaction of microorganisms and the cementing liquid and a part of liquid water is consumed, so that the strength of the soft soil is improved. The method has the following specific advantages:

(1) at present, three precipitation measures of tedding, light well point precipitation and electroosmosis precipitation are mainly adopted in actual engineering, and although the tedding precipitation has the advantages of simple construction, low cost and the like, the construction period is long, and the tedding precipitation is easily influenced by climate, temperature, humidity, wind speed, natural water content, tedding thickness and the like; the light well point dewatering has the advantages of flexible well point arrangement, convenient use and high dewatering rate, but the dewatering effect is limited by the vacuum suction; electroosmotic precipitation has the disadvantages of high power consumption, high cost and the like. Utilize polymer resin can reduce the moisture content of soft soil fast, traditional precipitation means is more economical and save time. In the subsequent reaction of the microorganisms and the cement, liquid water in the soil body is further consumed and calcium carbonate precipitate is generated, and compared with the traditional precipitation means, the method has the advantage of continuously improving the strength of the soil body.

(2) The cementing liquid with higher concentration is added into the soft soil, compared with the method of directly adding solid particles, the cementing liquid with higher concentration can be well and uniformly stirred with the soft soil, and the concentration of the cementing liquid can meet the requirement of microbial reaction through the dilution of liquid water in the soft soil. This allows the reaction of the microorganisms with the cement to be more evenly distributed in the soft soil.

(3) The reaction of the microorganisms in the soft soil is affected by the problem of the compatibility of individual microorganisms and the pore size of the soft soil, and the added high polymer resin can form particles of 0.5-2 mm after absorbing water. These particles contain microorganisms and a cement, so that the microbial reaction is not affected by compatibility with the size of soft soil, and calcium carbonate precipitation can be normally generated to strengthen the soft soil.

Drawings

FIG. 1 is a flow chart of the method for fast resource utilization of soft soil by combining microorganisms and high molecular resin.

Fig. 2 is a construction flow chart of the roadbed filling made by the invention.

Detailed description of the invention

With reference to fig. 1, a method for fast resource utilization of soft soil by combining microorganisms and high molecular resin comprises the following steps:

step 1) mixing urease-producing bacteria with good activity with cementing liquid raw materials to form a microorganism + cementing material suspension with higher concentration.

Wherein, the urease-producing bacteria are bacillus pasteurianus; the cementing liquid comprises solid calcium chloride and urea.

The concentration of calcium chloride and urea in the microorganism + cementing material turbid liquid with higher concentration is 5-8 mol/L, and the concentration of the microorganism is 2-4 multiplied by 10¹¹CFU/L。

And 2) selecting a proper amount of polymer resin, and stirring and mixing the polymer resin with the microorganism and the cement suspension to obtain a mixture of the polymer resin and the microorganism and the cement suspension.

The high polymer resin is water-absorbent resin, and the water absorption rate of the high polymer resin is 400-800 times.

The polymer resin has hydrophilic groups and a certain crosslinking degree, can keep the synthetic resin from outflow after absorbing a large amount of moisture, and can absorb moisture which is 500-2000 times of the self weight.

The mixture of the polymer resin and the microorganism and the cementing material turbid liquid comprises 555-888 g/L of calcium chloride, 300-480 g/L of urea and 2-4 x 10 of microorganism¹¹CFU/L, 60-120 g/L of polymer resin and 1000g/L of water.

And 3) fully mixing the mixture of the polymer resin, the microorganism and the cement turbid liquid with the soft soil, so that the polymer resin absorbs pore water in the soft soil, the water content of the soft soil can be rapidly reduced, and the water content of the soft soil is reduced to the optimal water content of the soft soil plus 6-8%.

Wherein, the mixture of polymer resin and microorganism + cementing material turbid liquid is 25~35L with the mixing ratio of soft soil: 1000L.

Step 4), the polymer resin, the microorganism and the cementing material suspension mixed into the soft soil and water absorbed by the polymer resin form micro MICP reaction particles, after a certain reaction time (the reaction time is 36-72 hours), the microorganism and the cementing material react to generate calcium carbonate precipitates, and the filling effect of the calcium carbonate precipitates can obviously improve the strength of the micro MICP reaction particles; and meanwhile, liquid water is consumed in the reaction, so that the obtained soil body water content is closer to the optimal water content.

And 5) uniformly mixing 4-7% of lime with the soil body obtained in the step 4) to form roadbed filling soil.

And 6) paving the roadbed filling soil on the roadbed, controlling the thickness of each layer to be 20-40 cm, and performing layered rolling forming on the paved soil body to finish the resource treatment of the soft soil.

With reference to fig. 2, the construction process of the roadbed filling soil prepared by the invention is as follows:

firstly, before roadbed construction, ensuring that each point has accurate coordinates, the elevation, the compactness, the flatness and the like meet the standard requirements, the field is clean and has no sundries, excavating soft soil, standing beside a roadbed to be filled,

And secondly, paving the whole section of the soft soil solidified soil for the first time by adopting a bulldozer according to the loose paving thickness, shaping the whole section by using a grader according to a specified road arch, and quickly performing static pressure once by using a road roller so as to expose potential unevenness. Then the manual work is matched, and the land leveler is finally leveled.

Thirdly, the compaction of the solidified soft soil filling roadbed comprises vibration compaction and impact compaction, and the vibration compaction is adopted for carrying out initial compaction after each layer of solidified soft soil is paved; and each two layers of solidified soft soil are impacted and compacted once after being paved, so that the compaction degree of the roadbed is further improved, and the post-construction settlement of the roadbed is reduced.

And fourthly, after rolling, detecting control indexes such as the thickness, the compactness, the strength and the like of the filled roadbed, wherein the core is the compactness.

And fifthly, performing sealing treatment by clay, performing timely treatment according to design requirements after the solidified soft soil filling roadbed reaches the roadbed elevation sealing position, and performing maintenance treatment if the sealing cannot be performed timely.

In conclusion, the method for quickly recycling the soft soil by using the microorganisms and the polymer resin can quickly reduce the water content of the soft soil to be + 6-8% of the optimal water content. The high molecular resin absorbs water to form 0.5-2 mm particles, the particles contain microorganisms, cementing liquid and liquid water, the concentration of the cementing liquid can meet the requirement of microbial reaction under the dilution of the liquid water, and the reaction is carried out in the high molecular particles and is not influenced by the incompatibility of soft soil pores and microorganisms, so that the generation amount of calcium carbonate is not influenced, and the strength of soft soil can meet the requirement of roadbed filling. The invention simplifies the construction steps, reduces the construction cost, shortens the construction period and has good economic benefit.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalent alternatives or equivalent variations fall within the scope of the present invention.