On-site rapid mixing method and device for microorganism modified special soil

Abstract

The invention provides a microorganism modified special soil on-site rapid mixing method and device.The mixing method comprises the steps that special soil is rotationally crushed in a screen drum of a screening hopper system, and to-be-modified soil is obtained; carrying out amplification culture on the bacterial liquid, and mixing the cementing liquid and the cultured bacterial liquid in a stirrer to obtain a glue-bacteria mixture; the glue bacterium mixture is conveyed into a grouting pipe through a grouting system; meanwhile, pressurized air is conveyed into a grouting pipe through a grouting system by using an air compressor; after being mixed with pressurized air, the gelatinomycete mixture is sprayed out towards the to-be-modified soil through a slurry spraying hole in the tail end of the grouting pipe, and the sprayed liquid is in an atomized state; and fully mixing the sprayed liquid with the to-be-modified soil to obtain the microorganism modified special soil. According to the method, the to-be-modified soil can be excavated, screened and crushed and is fully mixed with the microorganism modified material blended and sprayed by the grouting system, the mixing process is rapid and uniform, the field mixing uniformity of the microorganism modified special soil can be improved, the construction period can be shortened, and the method is economical and efficient.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical engineering foundation treatment, and in particular to a method and device for quickly mixing microbially modified special soil on site. Background Art

[0002] In slope and foundation engineering of special soils (such as loess, expansive soil, red clay, etc.), slope instability and foundation deformation often occur due to the soil's own characteristics, and modification is required to meet the bearing requirements. There are two main traditional modification methods: One method is to use an excavator to mix cement or lime on site. However, this method has many disadvantages, such as uneven mixing on site, which can easily lead to unstable modification effects, and often waste modified materials due to improper operation. In addition, the equipment operation and mixing process consume a lot of energy. Another method is to transport the soil to be modified to a mixing station and mix it with cement, lime, etc. However, this method faces the problem of long mixing time. It takes a lot of time from transportation to mixing, and the initial equipment investment is large. The subsequent operation and maintenance costs are high, and the overall cost remains high.

[0003] In response to the above problems, microbial modified special soil technology came into being. It stands out with the advantages of low energy consumption and low pollution. It strengthens the soil through microbial mineralization and can effectively improve the soil's strength characteristics, permeability and crack resistance.

[0004] However, there is currently a lack of a rapid mixing device that can be combined with a commonly used backhoe excavator to achieve on-site rapid excavation, crushing, uniform mixing, and rolling to meet the needs of on-site rapid and efficient mixing of microbially modified special soils. This has become a technical problem that needs to be solved urgently. Summary of the Invention

[0005] To solve the above problems, the present invention proposes a method and device for rapid on-site mixing of microbially modified special soil, which solves the technical problem in the existing technology that in slope and foundation engineering of special soil, the soil's own characteristics often lead to slope instability and foundation deformation, and modification is required to meet the bearing requirements.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: In a first aspect, the present invention provides a method for rapid on-site mixing of microbially modified special soil, comprising the following steps: S1. The special soil is crushed by rotation in the screen drum of the screening bucket system to obtain the soil to be modified; S2, expanding the bacterial liquid and mixing the binder liquid with the cultured bacterial liquid in a mixer to obtain a gelatin-bacteria mixture; delivering the gelatin-bacteria mixture to a grouting pipe via a grouting system; and simultaneously, using an air compressor to deliver pressurized air to the grouting pipe via the grouting system; S3, the colloid-bacteria mixture is mixed with the pressurized air and then sprayed toward the soil to be modified through the spray hole at the end of the grouting pipe, and the spray liquid is in an atomized state; S4. The spray liquid is fully mixed with the soil to be modified to obtain microbial modified special soil.

[0007] On the basis of the above technical solution, further, in step S2, during the expansion culture of the bacterial solution, the bacterial solution culture conditions are: pH is controlled between 7 and 10.

[0008] Furthermore, the bacterial strain of the bacterial solution is Sporosarcina pasteurii, the bacterial solution concentration OD600 is 1.5-3.5, and the urease activity is 9.5-19.5 mM urea hydrolyzed∙min -1 .

[0009] Furthermore, the volume ratio of the bacterial liquid to the binder liquid is 1:3.

[0010] Furthermore, the binder solution is a mixture of urea solution and calcium chloride solution.

[0011] Furthermore, the concentration of the urea solution is 0.8-1.2 mol / L; The molar concentration ratio of the urea solution to the calcium chloride solution is 1:(1-3).

[0012] Furthermore, in step S4, the mixing temperature is between 20°C and 40°C, and the mixing time is controlled to be completed within 24 hours.

[0013] Furthermore, step S1 specifically includes: the screening bucket system digs the modified soil into the screen drum, controls the through-core hydraulic motor to drive the screen drum to rotate, and crushes the modified soil in the screen drum.

[0014] In a second aspect, the present invention further provides a microbial modified special soil on-site rapid mixing device for performing the microbial modified special soil on-site rapid mixing method as described in the first aspect, comprising: a grouting system and a screening bucket system; The screening bucket system includes a frame, a bucket is provided on the front side of the frame, and a screen drum is installed inside the frame; a quick-connect connector connected to the excavator is installed above the frame; a mounting base connected to the screen drum is installed on the rear side of the frame, and the mounting base is connected to the through-core hydraulic motor through a flange, a rotary bearing is installed inside the through-core hydraulic motor, and a grouting pipe is installed inside the rotary bearing; The grouting system includes a first pipeline and a second pipeline, and the first pipeline and the second pipeline are commonly connected to the grouting pipe.

[0015] On the basis of the above technical solution, further, the first pipeline is connected to a mixer and a grouting pump, and the second pipeline is connected to an air compressor and a gas meter; The mixer is used to mix the binder liquid and the bacterial liquid. The mixed binder-bacteria mixture is transported to the grouting pipe by the grouting pump through the first pipeline. The air compressor is used to transport pressurized air to the grouting pipe through the second pipeline and the gas meter.

[0016] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: The method and device for rapid on-site mixing of microbial modified special soil can excavate, screen and crush the special soil to be modified, and fully mix it with the microbial modified material sprayed out by the grouting system in the screening bucket system. The mixing process is fast and uniform. Combined with the excavator compaction process, it can improve the on-site mixing uniformity of the microbial modified special soil and shorten the construction period, ensuring construction quality, and being economical and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of a process for rapidly mixing microbially modified special soil on site according to an embodiment of the present invention; Figure 2 A schematic diagram of the growth curve of Sporosarcina pasteurii provided in an embodiment of the present invention; Figure 3 A schematic structural diagram of a screening bucket system of a microbially modified special soil rapid on-site mixing device provided in an embodiment of the present invention; Figure 4 A schematic diagram of the structure of a device for rapidly mixing special soil modified by microorganisms according to an embodiment of the present invention; In the accompanying drawings, the components represented by the reference numerals are as follows: 1. Bucket; 2. Frame; 3. Screen drum; 4. Quick-connect joint; 5. Mounting base; 6. Through-hole hydraulic motor; 7. Rotary bearing; 8. Grouting pipe; 9. Spray hole; 10. First pipeline; 11. Second pipeline; 12. Mixer; 13. Grouting pump; 14. Air compressor; 15. Gas meter; 16. Binder; 17. Bacterial solution. DETAILED DESCRIPTION

[0018] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the scope of protection of the present invention.

[0019] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0020] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0021] In the present invention, the raw materials are all commercially available.

[0022] The embodiment of the present invention provides a method for quickly mixing special soil modified by microorganisms on site, such as Figure 1 As shown, the following steps are included: S1. The special soil is crushed by rotation in the screen drum of the screening bucket system to obtain the soil to be modified.

[0023] Specifically, the screening bucket system digs the modified soil into the screen drum, controls the movement of the through-core hydraulic motor, drives the screen drum to rotate, and crushes the modified soil in the screen drum.

[0024] S2. Expand and culture the bacterial liquid, mix the binder liquid and the cultured bacterial liquid in a mixer to obtain a gelatin-bacteria mixture; transport the gelatin-bacteria mixture to the grouting pipe through the grouting system; at the same time, use an air compressor to transport pressurized air to the grouting pipe through the grouting system.

[0025] The culture conditions of the bacterial solution during the expansion culture are as follows: pH is controlled between 7 and 10. The growth curve of Bacillus pasteurianus is shown in FIG. Figure 2 As shown, it can be seen that the pasteurian sporosarcina bacterial liquid has a good activity effect.

[0026] The bacterial strain of the culture was Bacillus pasteurii, with a concentration of OD600 of 1.5-3.5 and a urease activity of 9.5-19.5 mM urea hydrolyzed∙min -1 (In 1 mL of reaction system, 1 mmol / L urea is consumed per minute).

[0027] The volume ratio of bacterial liquid to cementing liquid is 1:3.

[0028] Specifically, the binder is a mixture of urea solution and calcium chloride solution.

[0029] The concentration of the urea solution is 0.8~1.2mol / L; the molar concentration ratio of the urea solution to the calcium chloride solution is 1:(1~3).

[0030] Specifically, the concentration of the urea solution is preferably 1 mol / L (6 g of urea is dissolved in 100 mL of water); the molar concentration ratio of the urea solution to the calcium chloride solution is preferably 1:2.

[0031] S3. The colloid-bacteria mixture is mixed with pressurized air and then sprayed toward the soil to be modified through the spray hole at the end of the grouting pipe, and the spray liquid is in an atomized state.

[0032] S4. The spray liquid is fully mixed with the soil to be modified to obtain the microbial modified special soil.

[0033] The mixing temperature is between 20 and 40°C, and the mixing time is controlled to be completed within 24 hours.

[0034] Correspondingly, an embodiment of the present invention further provides a microbial modified special soil on-site rapid mixing device for executing the above-mentioned microbial modified special soil on-site rapid mixing method, comprising: a grouting system and a screening bucket system.

[0035] Among them, Figure 3 As shown, the screening bucket system includes a frame 2, a bucket 1 is provided on the front side of the frame 2, a screen drum 3 is installed inside the frame 2; a quick connector 4 connected to the excavator is installed on the top of the frame 2; a mounting base 5 connected to the screen drum 3 is installed on the rear side of the frame 2; Figure 4 As shown, the mounting base 5 is connected to the through-core hydraulic motor 6 via a flange, a rotary bearing 7 is installed inside the through-core hydraulic motor 6 , and a grouting pipe 8 is installed inside the rotary bearing 7 .

[0036] like Figure 4 As shown, the grouting system includes a first pipeline 10 and a second pipeline 11 , and the first pipeline 10 and the second pipeline 11 are commonly connected to the grouting pipe 8 .

[0037] Further, such as Figure 4 As shown, the first pipeline 10 is connected to a mixer 12 and a grouting pump 13 , and the second pipeline 11 is connected to a gas meter 15 and an air compressor 14 .

[0038] The mixer 12 is used to mix the binder 16 and the bacterial solution 17. The mixed binder-bacteria mixture is transported to the grouting pipe 8 through the first pipeline 10 by the grouting pump 13. The air compressor 14 is used to transport pressurized air to the grouting pipe 8 through the second pipeline 11 and the gas meter 15.

[0039] Specifically, the through-hole hydraulic motor 6 in the screening bucket system rotates to drive the base and the screen drum 3 connected to the base to rotate, and the grouting pipe 8 in the rotary bearing 7 connected to the through-hole hydraulic motor 6 remains stationary. The soil rotates and crushes in the screen drum 3, and the grouting liquid is ejected through the grouting hole at the end of the grouting pipe 8 and is evenly mixed with the soil.

[0040] One end of the grouting pipe 8 penetrates 15 to 25 cm into the interior of the screen drum 3, and the other end passes through the through-core hydraulic motor 6 and is connected to the grouting system. A grouting hole is arranged at the end of the grouting pipe 8 that penetrates into the screen drum 3; the grouting hole is in an inverted trapezoidal shape and is symmetrically arranged at the end of the grouting pipe 8. The slurry is evenly sprayed out through the grouting hole, and the spray is in an atomized state. It is rotated and mixed with the above-mentioned broken soil in the screen drum 3, and the agglomerated mixed soil is also broken again during rotation. After sufficient mixing, the soil can be poured out from the bucket 1 and spread flat on the site. It is rolled to the designed compaction degree according to the design requirements. The on-site rapid mixing method and device of the microbially modified special soil ensures the mixing uniformity.

[0041] Compared with the existing technology, the method and device for rapid on-site mixing of microbially modified special soil provided in this embodiment have the following beneficial technical effects: the special soil to be modified can be excavated, screened and crushed, and fully mixed with the microbial modified material sprayed out through the grouting system in the screening bucket system. The mixing process is fast and uniform. Combined with the excavator compaction process, the on-site mixing uniformity of the microbially modified special soil can be improved and the construction period can be shortened, thereby ensuring construction quality, being economical and efficient.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for rapid on-site mixing of microbially modified special soil, characterized in that: The steps include: S1. The special soil is crushed by rotation in the screen drum of the screening bucket system to obtain the soil to be modified; S2, expanding the bacterial liquid and mixing the binder liquid with the cultured bacterial liquid in a mixer to obtain a gelatin-bacteria mixture; delivering the gelatin-bacteria mixture to a grouting pipe via a grouting system; and simultaneously, using an air compressor to deliver pressurized air to the grouting pipe via the grouting system; S3, the colloid-bacteria mixture is mixed with the pressurized air and then sprayed toward the soil to be modified through the spray hole at the end of the grouting pipe, and the spray liquid is in an atomized state; S4. The spray liquid is fully mixed with the soil to be modified to obtain microbial modified special soil.

2. The method for rapid on-site mixing of microbial modified special soil according to claim 1, characterized in that: In step S2, the bacterial solution is expanded and cultured under the following conditions: pH is controlled between 7 and 10.

3. The method for rapid on-site mixing of microbial modified special soil according to claim 2, characterized in that: The bacterial strain of the bacterial solution is Sporosarcina pasteurii, the bacterial solution concentration OD600 is 1.5-3.5, and the urease activity is 9.5-19.5 mM ureahydrolyzed∙min -1 .

4. The method for rapid on-site mixing of microbial modified special soil according to claim 3, characterized in that: The volume ratio of the bacterial liquid to the cementing liquid is 1:

3.

5. The on-site rapid mixing method of microbial modified special soil according to claim 1, characterized in that: The cementing liquid is a mixture of urea solution and calcium chloride solution.

6. The method for rapid on-site mixing of microbial modified special soil according to claim 5, characterized in that: The concentration of the urea solution is 0.8-1.2 mol / L; The molar concentration ratio of the urea solution to the calcium chloride solution is 1:(1-3).

7. The method for rapid on-site mixing of microbial modified special soil according to claim 1, characterized in that: In step S4, the mixing temperature is between 20°C and 40°C, and the mixing time is controlled to be completed within 24 hours.

8. The method for rapid on-site mixing of microbial modified special soil according to claim 1, characterized in that: Step S1 specifically includes: the screening bucket system digs the modified soil into the screen drum, controls the through-core hydraulic motor to drive the screen drum to rotate, and crushes the modified soil in the screen drum.

9. A microbial modified special soil on-site rapid mixing device for performing the microbial modified special soil on-site rapid mixing method according to any one of claims 1 to 8, characterized in that: include: Grouting system and screening bucket system; The screening bucket system includes a frame, a bucket is provided on the front side of the frame, and a screen drum is installed inside the frame; a quick-connect connector connected to the excavator is installed above the frame; a mounting base connected to the screen drum is installed on the rear side of the frame, and the mounting base is connected to the through-core hydraulic motor through a flange, a rotary bearing is installed inside the through-core hydraulic motor, and a grouting pipe is installed inside the rotary bearing; The grouting system includes a first pipeline and a second pipeline, and the first pipeline and the second pipeline are commonly connected to the grouting pipe.

10. The on-site rapid mixing device for microbial modified special soil according to claim 9, characterized in that: The first pipeline is connected to a mixer and a grouting pump, and the second pipeline is connected to an air compressor and a gas meter; The mixer is used to mix the binder liquid and the bacterial liquid. The mixed binder-bacteria mixture is transported to the grouting pipe by the grouting pump through the first pipeline. The air compressor is used to transport pressurized air to the grouting pipe through the second pipeline and the gas meter.

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