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CN-121992769-A - MICP-based precise grouting reinforcement method

CN121992769ACN 121992769 ACN121992769 ACN 121992769ACN-121992769-A

Abstract

The invention discloses a MICP-based precise grouting reinforcement method which comprises the following steps of S1, arranging a grouting conduit in a soil body, wherein the soil body is silt soil, the permeability coefficient of the silt soil is (1.15-1.25) multiplied by 10 ‑5 m/S, S2, mixing prepared bacterial liquid and cementing liquid to obtain slurry, and injecting the slurry into the soil body through the grouting conduit, wherein the injection process is to perform grouting for 0.15-0.25min by using the pressure of 0.22-0.26MPa, so that a region to be reinforced with gradually reduced pore pressure in the peripheral diffusion direction by using the grouting conduit as the center is formed in a certain range in a target reinforcement layer of the soil body, and then performing secondary grouting on the region to be reinforced by using the pressure of 0.14-0.16 MPa. The invention can solve the problem of slurry loss and uneven distribution in the traditional MICP technology, so that the bacterial liquid retention rate in the soil body is more than 95%, the calcium carbonate distribution CV is less than or equal to 0.12, and the soil body strength is improved to about 50%.

Inventors

  • LI LIHUA
  • Geng Weijuan
  • ZHANG ZIQI
  • HUANG YANYAN
  • GAN LEI
  • CHEN LIANG
  • WAN JUAN
  • LIU YIMING
  • HUANG YI
  • LI WENTAO

Assignees

  • 湖北工业大学
  • 西藏农牧大学

Dates

Publication Date
20260508
Application Date
20260325

Claims (10)

  1. 1. The MICP-based precise grouting reinforcement method is characterized by comprising the following steps of: S1, arranging grouting guide pipes in a soil body, wherein the soil body is silt soil, and the permeability coefficient of the silt soil is (1.15-1.25) multiplied by 10 -5 m/S; S2, mixing the prepared bacterial liquid and the cementing liquid to obtain slurry, and injecting the slurry into the soil body through a grouting guide pipe, wherein the injection process is to perform grouting for 0.15-0.25min at a pressure of 0.22-0.26MPa, so that a region to be reinforced with gradually decreasing pore pressure in the peripheral diffusion direction by taking the grouting guide pipe as the center is formed in a certain range in a target reinforcing layer of the soil body, and then perform secondary grouting on the region to be reinforced at a pressure of 0.14-0.16 MPa.
  2. 2. The MICP-based precise grouting reinforcement method of claim 1, wherein the grouting guide pipe is arranged in the soil body, specifically, the distance from the bottom end of the grouting guide pipe to the bottom surface of the target reinforcement layer, which is inserted into the target reinforcement layer of the soil body, is 1/2-2/3 of the thickness of the target reinforcement layer.
  3. 3. The MICP-based accurate grouting reinforcement method of claim 2, wherein the grouting guide pipe is inserted into the pipe section of the target reinforcement layer to form a plurality of grouting holes at intervals.
  4. 4. The MICP-based accurate grouting reinforcement method of claim 3, wherein the grouting holes have a diameter of 1-2mm.
  5. 5. The MICP-based precise grouting reinforcement method of claim 1, wherein the bacterial liquid is a spore suspension of Bacillus pasteurii with a concentration of 1X 10 8 -5×10 8 CFU/mL.
  6. 6. The method of MICP-based precision grouting reinforcement of claim 1, wherein said cement comprises 0.5-1.0M urea and 0.5-1.0M calcium chloride.
  7. 7. The MICP-based precise grouting reinforcement method of claim 1, wherein the mixing ratio of the bacterial liquid to the cementing liquid is 1:0.9-1.1.
  8. 8. The MICP-based precise grouting reinforcement method of claim 1, wherein the bacterial liquid is stored in a constant temperature bacterial liquid storage tank to maintain bacterial liquid activity.
  9. 9. The MICP-based precise grouting reinforcement method of claim 8, wherein the constant-temperature storage temperature of the bacterial liquid is 18-22 ℃.
  10. 10. The MICP-based accurate grouting reinforcement method of claim 1, wherein the pressure control accuracy in the grouting process is not lower than + -0.01 MPa.

Description

MICP-based precise grouting reinforcement method Technical Field The invention relates to the technical field of geotechnical engineering reinforcement, in particular to an accurate grouting reinforcement method based on MICP. Background Microorganism-induced calcium carbonate precipitation (MICP) is an emerging green rock-soil reinforcement technology that produces calcium carbonate precipitates through microbial metabolic activity, cementing loose soil particles, and thereby improving the mechanical properties of the soil body. The traditional MICP reinforcement method is characterized in that bacterial liquid and nutrient (cementing agent) are directly injected into soil body or conveyed into the soil body through a pre-buried pipeline according to constant injection parameters, and the method has obvious defects that slurry containing bacterial liquid is easy to run off along with underground water, the utilization rate is low, a dominant seepage channel is easy to form in the soil body due to constant injection pressure, and the problems of slurry running off and non-uniformity are further aggravated. In view of the above, it is necessary to design a precise grouting reinforcement method based on MICP to solve the above problems. Disclosure of Invention The invention aims to provide an accurate grouting reinforcement method based on MICP, which aims to solve the problems of slurry loss and uneven distribution in the traditional MICP technology. In order to achieve the above object, the present invention provides a precise grouting reinforcement method based on MICP, comprising the following steps: S1, arranging grouting guide pipes in a soil body, wherein the soil body is silt soil, and the permeability coefficient of the silt soil is (1.15-1.25) multiplied by 10 -5 m/S; S2, mixing the prepared bacterial liquid and the cementing liquid to obtain slurry, and injecting the slurry into the soil body through a grouting guide pipe, wherein the injection process is to perform grouting for 0.15-0.25min at a pressure of 0.22-0.26MPa, so that a region to be reinforced with gradually decreasing pore pressure in the peripheral diffusion direction by taking the grouting guide pipe as the center is formed in a certain range in a target reinforcing layer of the soil body, and then perform secondary grouting on the region to be reinforced at a pressure of 0.14-0.16 MPa. As a further improvement of the invention, the grouting guide pipe is arranged in the soil body, and the distance from the bottom end of the grouting guide pipe to the bottom surface of the target reinforcing layer, which is inserted into the soil body, is 1/2-2/3 of the thickness of the target reinforcing layer. As a further improvement of the invention, a plurality of grouting holes are arranged on the pipe section of the grouting guide pipe inserted into the target reinforcing layer at intervals. As a further improvement of the invention, the aperture of the grouting holes is 1-2mm. As a further improvement of the invention, the bacterial liquid is a spore suspension of the bacillus pasteurizer, the concentration is 1 multiplied by 10 8-5×108 CFU/mL, and the cementing liquid comprises 0.5-1.0M urea and 0.5-1.0M calcium chloride. As a further improvement of the invention, the mixing ratio of the bacterial liquid and the cementing liquid is 1:0.9-1.1. As a further improvement of the invention, the bacterial liquid is stored in a constant temperature bacterial liquid storage tank to maintain the bacterial liquid activity. As a further improvement of the invention, the constant temperature storage temperature of the bacterial liquid is 18-22 ℃. As a further improvement of the invention, the pressure control precision in the grouting process is not lower than +/-0.01 MPa. The beneficial effects of the invention are as follows: The invention can form a region to be reinforced with gradually decreasing pore pressure in the peripheral diffusion direction by establishing a 'first high-pressure short-time activation-then low-pressure steady diffusion' two-stage grouting method, so as to provide driving force for slurry to diffuse along the center of a grouting conduit to the periphery by using a pressure change field, and then continuously and uniformly fill the slurry in the pores of the soil body under the driving of a pressure gradient in a low-pressure grouting mode, thereby avoiding the conditions that the dominant seepage channel caused by the existing constant grouting pressure influences grouting uniformity and causes slurry loss, and effectively improving the bacterial liquid retention rate, the distribution uniformity of calcium carbonate and the soil body strength in the soil body, wherein the bacterial liquid retention rate is more than 95%, the calcium carbonate distribution CV is less than or equal to 0.12 and the soil body strength is improved to about 50%. Drawings Fig. 1 is a schematic diagram of a MICP-based precision grouting reinforcement