CN108396736B - Construction device and construction method for manufacturing MICP-based composite stiffening core pile - Google Patents
Construction device and construction method for manufacturing MICP-based composite stiffening core pile Download PDFInfo
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- CN108396736B CN108396736B CN201810456134.2A CN201810456134A CN108396736B CN 108396736 B CN108396736 B CN 108396736B CN 201810456134 A CN201810456134 A CN 201810456134A CN 108396736 B CN108396736 B CN 108396736B
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D15/00—Handling building or like materials for hydraulic engineering or foundations
- E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
- E02D15/04—Placing concrete in mould-pipes, pile tubes, bore-holes or narrow shafts
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D19/00—Keeping dry foundation sites or other areas in the ground
- E02D19/06—Restraining of underground water
- E02D19/12—Restraining of underground water by damming or interrupting the passage of underground water
Abstract
The invention discloses a construction device for manufacturing a composite stiffening core pile, which comprises an outer sinking pipe and an inner sinking pipe, wherein the outer sinking pipe and the inner sinking pipe form a double-cylinder structure, and the pipe wall of the outer sinking pipe is of a double-layer structure and is used for supporting a fence; a cavity is formed between the inner pipe wall and the outer pipe wall of the outer immersed pipe; the cavity is connected with the infusion tube by adopting a thread sleeve head, the infusion tube is used for conveying bacterial liquid and reinforcing liquid into the cavity, and a liquid guide hole is arranged on the tube surface of the inner tube wall of the outer immersed tube; the invention also discloses a construction method by using the construction device for manufacturing the composite stiffening core pile, which has the advantages of good water-proof performance, high strength, little environmental pollution, parallel operation with other processes during construction and effective shortening of construction period.
Description
Technical Field
The invention relates to a construction device and a construction method of a composite stiffening core pile, in particular to a construction device and a construction method for manufacturing a composite stiffening core pile based on MICP.
Background
The pile foundation is not only a long-history foundation type, but also a foundation type which is widely applied, rapidly developed and very strong in vitality. Urban construction is three-dimensional, traffic is high-speed, and improvement of comprehensive living environment has become a characteristic of modern civil engineering. Pile foundation technology is widely applied to various fields of civil engineering, and pile foundation technology is used for building engineering with larger construction scale, or is used as a pile foundation for supporting the weight of a building, or is used as a foundation pit excavation supporting structure. With the continuous development of scientific technology, engineering construction and industrial technology, the types and pile foundation types of piles, construction processes and equipment, and pile foundation theory and design methods have evolved greatly. The pile foundation has the characteristics of high bearing capacity, good stability, small sedimentation and differential sedimentation, stable and fast sedimentation, good earthquake resistance, adaptability to various complex geological conditions and the like, so that the pile foundation is widely applied, however, common piles have high manufacturing cost due to high steel consumption or severe secondary pollution to the environment due to high concrete consumption.
Disclosure of Invention
The invention aims to solve the problems and provide a construction device and a construction method for manufacturing a composite stiffening core pile based on MICP, which have the advantages of water sealing property, certain bearing capacity and long-term stability, and simultaneously, the construction cost and the construction time are reduced in engineering.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the construction device for manufacturing the composite stiffening core pile based on the MICP comprises an outer sinking pipe and an inner sinking pipe, wherein the outer sinking pipe and the inner sinking pipe form a double-cylinder structure, and the pipe wall of the outer sinking pipe is of a double-layer structure and is used for supporting a fence; a cavity is formed between the inner pipe wall and the outer pipe wall of the outer immersed pipe; the cavity is connected with the infusion tube by adopting a thread sleeve head, the infusion tube is used for conveying bacterial liquid and reinforcing liquid into the cavity, and a liquid guide hole is arranged on the tube surface of the inner tube wall of the outer immersed tube; the inner immersed tube is of a single-layer structure and is mainly used for enclosing, and the inner immersed tube is connected with the water pump unit through the water suction tube.
The diameter of the liquid guide hole is 14-15 mm, the liquid guide holes are distributed on the pipe surface of the inner pipe wall of the outer sinking pipe in a quincuncial shape, and the area of the liquid guide hole is 15-20% of the area of the pipe surface of the inner pipe wall of the outer sinking pipe.
The outer immersed tube and the outer immersed tube are steel immersed tubes, so that a good enclosing effect is achieved, and the overall strength is improved.
The outer immersed tube is connected with the cathode of the power supply to form cathode protection, so that the effect of rust prevention of the immersed tube is realized.
A construction method for utilizing a construction device for manufacturing a composite stiffening core pile based on MICP comprises the following specific steps:
step one: measuring on a flattened field according to design requirements, placing a marking line, and determining pile positions of the stiffening core piles;
step two: determining hole sites according to design requirements, and marking;
step three: drilling by using a drilling machine, drilling a stratum by using a drill rod, keeping a wall protection sleeve along, enabling flushing medium to enter the drilling hole through a channel of the drill rod and a drill bit, and discharging drilling waste residues along the space between the drill rod and the sleeve;
step four: starting a vibrator, sinking the outer immersed tube into the soil for 3.0-5.0 meters, standing for a short time to observe the effect of the immersed tube, observing the condition of surrounding soil, if no bulge exists, continuing the step five, if the bulge exists, suspending the vibrator, and continuing sinking the outer immersed tube into the soil after repairing;
step five: continuously starting the vibrator, sinking the outer sinking pipe to a set depth, and keeping vibrating for 1 minute every 2.0 meters in the sinking process;
step six: repeating the fourth step to the fifth step, and sinking into the inner sinking pipe;
step seven: preparing a pulse-producing enzyme bacterial solution and a strengthening solution which are needed by microorganism mineralization; the pulse-producing enzyme bacterial solution is composed of nutrition salt solution with the concentration of OD600 = 1.5, which is necessary for the vital activity of the armillaria pastoris; the strengthening solution is prepared by mixing a calcium chloride solution with the concentration of 0.5-1.2 mol/L and a urea solution with the concentration of 0.5-1.2 mol/L;
step eight: connecting a water suction pump unit into an inner immersed tube, connecting a liquid delivery tube for delivering the pulse enzyme-producing bacterial liquid with the inner wall of an outer immersed tube, opening the water suction pump unit and the liquid delivery tube, and forming a stable seepage field in soil between the inner immersed tube and the outer immersed tube by utilizing the water head difference between the inner immersed tube and the outer immersed tube so that the pulse enzyme-producing bacterial liquid is diffused to the foundation around a drill hole and adsorbed on soil particles;
step nine: connecting the outer immersed tube with a direct current power supply cathode, and connecting the inner immersed tube with a direct current power supply anode; closing a switch of the direct current power supply, forming a direct current electric field between a transfusion tube of a cathode of the power supply and a water suction tube of an anode of the power supply, and cutting off the switch of the direct current power supply after the direct current electric field acts for 4-8 hours; the direct current electric field is applied at the moment that in the attaching stage of the pulse producing enzyme bacteria, the pulse producing enzyme bacteria with negative charges move to the power anode in an electrophoresis mode, so that the pulse producing enzyme bacteria enriched at the near end of the pulse producing enzyme bacteria liquid injection position migrate to the far end of the pulse producing enzyme bacteria liquid injection position, and the redistribution of the pulse producing enzyme bacteria in space is realized;
step ten: cutting off a direct current power supply, standing for 24 hours, connecting a perfusion tube for conveying reinforcing liquid to the inner wall of an outer immersed tube, simultaneously opening a water suction pump unit and the perfusion tube, forming a stable seepage field in soil body between the inner immersed tube and the outer immersed tube by utilizing the water head difference between the inner immersed tube and the outer immersed tube, diffusing the reinforcing liquid to the foundation around a drilling hole, and generating mineralization reaction with pulse producing enzyme bacteria adsorbed on soil body particles to generate calcium carbonate crystals with cementing effect;
step eleven: connecting the outer sinking pipe with a power cathode, and connecting the inner sinking pipe with a power anode; closing a switch of the direct current power supply, forming a direct current electric field between a transfusion tube of a cathode of the power supply and a water suction tube of an anode of the power supply, and cutting off the switch of the direct current power supply after the direct current electric field acts for 4-8 hours; the direct current electric field is applied at the moment that in the reinforcing liquid reaction stage, the negatively charged reinforcing liquid moves to the power anode in an electrophoresis mode, so that the reinforcing liquid enriched at the near end of the reinforcing liquid injection position migrates to the far end of the reinforcing liquid injection position, and the redistribution of the reinforcing liquid in space is realized;
step twelve: repeating the steps ten to eleven until the soil body is reinforced to the design strength;
step thirteen: manufacturing a concrete slurry stirring strength core in the inner immersed tube;
firstly, digging a foundation pit according to the design, and then continuously infusing the prepared concrete slurry which is not subjected to segregation by a conveying pump, and stirring by a stirrer for three times, namely primary spraying, primary stirring or secondary spraying; when the concrete slurry reaches the slurry outlet, spraying concrete slurry 30S at the pile base to enable the slurry to completely reach the pile end, and when the slurry outlet reaches the pile top elevation, stopping lifting by the stirrer, and stirring for a plurality of seconds again to ensure that the pile head of the stiffening core pile is uniform and compact;
step fourteen: after the microbial composite stiffening core pile is formed, a flexible permeable sand cushion layer is paved at the top of a foundation formed by the stiffening core pile and soil between piles, a pre-pressing load is applied at the top of the flexible permeable sand cushion layer, so that pore water in the soil between piles is discharged along a drainage channel formed by the sand pile and the flexible permeable sand cushion layer, soil between piles is solidified, the bearing capacity of the soil between piles is improved, and the microbial composite stiffening core pile, soft soil after drainage solidification and the overlying flexible permeable sand cushion layer jointly form the composite stiffening core pile with higher bearing capacity.
In the first step, pile positions of the stiffening core piles are placed at intervals.
In the second step, the interval error between every two holes in the horizontal direction is not more than 50mm, and the interval error between every two holes in the vertical direction is not more than 100mm; the deflection dimension of the bottom of the hole is not more than 3% of the design length; the depth of the hole is not less than the design length and not more than 1% of the design length.
In the third step, a drilling inclinometer is used for controlling the drilling direction, the angle deflection is not more than 3 degrees, and the drilled holes are prevented from deflection; when dry drilling holes, small augers are used to drill holes.
The nutrient salt solution contains 5.0g of soybean protein pulse, 15g of pancreas protein pulse, 5.0g of sodium chloride and 20g of urea, and the pH value of the nutrient salt solution is 7.3.
The water suction pump unit is a dry vacuum pump unit or a jet pump unit, the water collecting main pipe in the water suction pump unit is a steel pipe with the diameter of 75-150 mm, and the water collecting main pipe is connected with the inner immersed pipe by adopting a flange.
The strength of the direct current electric field is 0.5-1.0V/cm.
When the concrete slurry stirring strength core is manufactured in the inner immersed tube, the concrete slurry is 0.5m higher than the foundation ground; when the concrete slurry is stopped to be conveyed due to faults, the stirrer is sunk to the position 0.5m below the slurry stopping point, and when slurry supply is restored, the stirrer is lifted again, if the shutdown time exceeds 3 hours, the pipeline is cleaned, the concrete slurry is prevented from being hardened and blocking the pipeline, and the concrete slurry is maintained for 14 days after being infused.
The reinforcing depth of the stiffening core pile is not more than 20m, and when the dry construction is used, the reinforcing depth of the stiffening core pile is not more than 15m, the diameter of the inner sinking pipe is not less than 500mm, and the radius of the outer sinking pipe is not less than 1000mm.
The invention has the beneficial effects that:
the invention has the advantages of good water-proof performance, high strength, small environmental pollution, parallel operation with other processes during construction, effective shortening of construction period, application to extremely severe and severe environments in coastal areas, application to other environments, no influence of geographical environment and construction climate, small construction site, low noise in construction process, no influence on normal production and life of surrounding residents during construction in a city center, water sealing, excellent bearing capacity and long-term stability, engineering reduction of construction cost and construction time, no secondary pollution to environment during construction, and economic and environment protection; the interior sinking pipe barrel is of a single-layer structure and is used for enclosing, and uniformity of a reinforcing effect in the microorganism mineralization process can be ensured through seepage and electric field effects, so that the obtained reinforced soil body is higher in strength.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention;
fig. 2 is a flow chart of the method of the present invention.
Wherein, 1, an outer sinking pipe; 2. an inner sinking pipe; 3. a water pump unit; 4. a water pumping pipe; 5. an infusion tube; 6. a bacterial liquid container; 7. a reinforcement liquid container; 8. a power supply anode; 9. and a power cathode and 10. A composite stiffening core pile.
Description of the embodiments
The invention will be further described with reference to the drawings and examples.
As shown in fig. 1, a construction device for manufacturing a composite stiffening core pile based on MICP comprises an outer immersed tube 1 and an inner immersed tube 2, wherein the outer immersed tube 1 and the inner immersed tube 2 form a double-tube structure, and the tube wall of the outer immersed tube 1 is of a double-layer structure and is used for supporting a fence; a cavity is formed between the inner pipe wall and the outer pipe wall of the outer immersed pipe 1; the cavity is connected with the infusion tube 5 by adopting a thread sleeve, the infusion tube 5 is used for conveying the bacterial liquid in the bacterial liquid container 6 and the reinforcing liquid in the reinforcing liquid container 7 into the cavity, and a liquid guide hole is arranged on the tube surface of the inner tube wall of the outer immersed tube 1; the diameter of the liquid guide holes is 14-15 mm, the liquid guide holes are distributed on the pipe surface of the inner pipe wall of the outer immersed pipe 1 in a quincuncial shape, the area of the liquid guide holes is 15% -20% of the area of the pipe surface of the inner pipe wall of the outer immersed pipe 1, the inner immersed pipe 2 is of a single-layer structure, the liquid guide holes are mainly used for enclosing, and the inner immersed pipe 1 is connected with a water pump unit through a water pumping pipe 4.
The outer immersed tube 1 and the outer immersed tube 2 are steel immersed tubes, so that a good enclosure effect is achieved, the overall strength is improved, the outer immersed tube 1 is connected with a power cathode 9 to form cathode protection, the effect of rust prevention of the outer immersed tube 1 is achieved, and the inner immersed tube 2 is connected with a power anode 8.
As shown in fig. 2, a construction method using a construction apparatus for manufacturing a composite stiffening core pile based on MICP comprises the following specific steps:
step one: measuring on a flattened field according to design requirements, placing marking lines, determining pile positions of the stiffening core piles, and placing the pile positions of the stiffening core piles at intervals;
step two: determining hole sites according to design requirements, marking, wherein the interval error between every two horizontal hole sites is not more than 50mm, and the interval error between every two vertical hole sites is not more than 100mm; the deflection dimension of the bottom of the hole is not more than 3% of the design length; the depth of the hole is not less than the design length and not more than 1% of the design length;
step three: drilling by using a drilling machine, drilling a stratum by using a drill rod, keeping a wall sleeve, and then entering the drilling by using a flushing medium through a channel of the drill rod and a drill bit, discharging drilling waste residues along the space between the drill rod and the sleeve, wherein in order to ensure the perpendicularity of the drilling, a drilling inclinometer is used for controlling the drilling direction, the angle deflection is not more than 3 degrees, and the deflection of the drilled hole is prevented; drilling holes using a small auger while dry drilling holes;
step four: starting a vibrator, namely sinking the outer immersed tube 1 into the soil for 3.0-5.0 meters, standing for a short time to observe the immersed tube effect, observing the surrounding soil conditions, continuing the step five if no bulge exists, suspending the vibrator if the bulge exists, and continuously sinking the outer immersed tube 1 into the soil after repairing;
step five: continuously starting the vibrator, sinking the outer sinking pipe 1 to a set depth, and keeping vibrating for 1 minute every 2.0 meters in the sinking process;
step six: repeating the fourth step to the fifth step, and sinking into the inner sinking pipe 2;
step seven: preparing a pulse-producing enzyme bacterial solution and a strengthening solution which are needed by microorganism mineralization; the pulse-producing enzyme bacterial solution is composed of nutrition salt solution with the concentration of OD600 = 1.5, which is necessary for the vital activity of the armillaria pastoris; the strengthening solution is prepared by mixing a calcium chloride solution with the concentration of 0.5-1.2 mol/L and a urea solution with the concentration of 0.5-1.2 mol/L; each 100g of nutrient salt solution contains 5.0g of soybean protein pulse, 15g of pancreas protein pulse, 5.0g of sodium chloride and 20g of urea, and the pH value of the nutrient salt solution is 7.3;
step eight: the water pump unit 3 is connected into the inner immersed tube 2, the infusion tube 5 for conveying the pulse enzyme-producing bacterial liquid is connected with the inner wall of the outer immersed tube 1, the water pump unit 3 and the infusion tube 5 are opened, and a stable seepage field is formed in soil between the inner immersed tube 2 and the outer immersed tube 1 by utilizing the water head difference between the inner immersed tube 2 and the outer immersed tube 1, so that the pulse enzyme-producing bacterial liquid is diffused to the foundation around a drill hole and adsorbed on soil particles; the water suction pump unit is a dry vacuum pump unit or a jet pump unit, a water collecting main pipe in the water suction pump unit is a steel pipe with the diameter of 75-150 mm, and the water collecting main pipe is connected with the inner immersed pipe by adopting a flange;
step nine: step nine: connecting the outer immersed tube 1 with a direct current power supply cathode 9, and connecting the inner immersed tube 2 with a direct current power supply anode 8; closing a switch of a direct current power supply, forming a direct current electric field between the infusion tube 5 of the power supply cathode 9 and the water suction tube 4 of the power supply anode 8, and cutting off the switch of the direct current power supply after the direct current electric field acts for 4-8 hours; the direct current electric field is applied at the moment that in the attaching stage of the pulse producing enzyme bacteria, the pulse producing enzyme bacteria with negative charges move to the power anode 8 in an electrophoresis mode, so that the pulse producing enzyme bacteria enriched at the near end of the pulse producing enzyme bacteria liquid injection position migrate to the far end of the pulse producing enzyme bacteria liquid injection position, and the redistribution of the pulse producing enzyme bacteria in space is realized; the strength of the direct current electric field is 0.5-1.0V/cm;
step ten: cutting off a direct current power supply, standing for 24 hours, connecting a transfusion tube 5 for conveying reinforcing liquid into the inner wall of an outer immersed tube 1, simultaneously opening a water suction pump unit 3 and the transfusion tube 5, forming a stable seepage field in soil body between the inner immersed tube 2 and the outer immersed tube 1 by utilizing the water head difference between the inner immersed tube 2 and the outer immersed tube 1, diffusing the reinforcing liquid to the foundation around a drilling hole, and generating mineralization reaction with pulse producing enzyme bacteria adsorbed on soil body particles to generate calcium carbonate crystals with cementing effect;
step eleven: connecting the outer immersed tube 1 with a power cathode 9, and connecting the inner immersed tube 2 with a power anode 8; closing a switch of a direct current power supply, forming a direct current electric field between the infusion tube 5 of the power supply cathode 9 and the water suction tube 4 of the power supply anode 8, and cutting off the switch of the direct current power supply after the direct current electric field acts for 4-8 hours; the direct current electric field is applied at the moment that in the reinforcing liquid reaction stage, the negatively charged reinforcing liquid moves to the power anode 8 in an electrophoresis mode, so that the reinforcing liquid enriched at the near end of the reinforcing liquid injection position migrates to the far end of the reinforcing liquid injection position, and the redistribution of the reinforcing liquid in space is realized;
step twelve: repeating the steps ten to eleven until the soil body is reinforced to the design strength;
step thirteen: manufacturing a concrete slurry stirring strength core in the inner immersed tube 2;
firstly, digging a foundation pit according to the design, and then continuously infusing the prepared concrete slurry which is not subjected to segregation by a conveying pump, and stirring by a stirrer for three times, namely primary spraying, primary stirring or secondary spraying; when the concrete slurry reaches the slurry outlet, spraying concrete slurry 30S at the pile base to enable the slurry to completely reach the pile end, and when the slurry outlet reaches the pile top elevation, stopping lifting by the stirrer, and stirring for a plurality of seconds again to ensure that the pile head of the stiffening core pile is uniform and compact;
when the concrete slurry stirring strength core is manufactured in the inner immersed tube 2, the concrete slurry is 0.5 meter higher than the foundation ground; when the concrete slurry is stopped to be conveyed due to faults, the stirrer is sunk to the position 0.5m below the slurry stopping point, when slurry is recovered, lifting is performed again, if the shutdown time exceeds 3 hours, the pipeline is cleaned, the concrete slurry is prevented from hardening and blocking the pipeline, and the concrete slurry is cured for 14 days after being infused;
the reinforcing depth of the stiffening core pile is not more than 20m, and when dry construction is used, the reinforcing depth of the stiffening core pile is not more than 15m, the diameter of the inner sinking pipe 2 is not less than 500mm, and the radius of the outer sinking pipe 1 is not less than 1000mm;
step fourteen: after the microbial composite pile is formed, a flexible permeable sand cushion layer is paved at the top of a foundation formed by the microbial pile and soil between piles, a pre-pressing load is applied at the top of the flexible permeable sand cushion layer, so that pore water in the soil between piles is discharged along a drainage channel formed by the sand piles and the flexible permeable sand cushion layer, soil between piles is solidified, the bearing capacity of the soil between piles is improved, and the microbial composite pile, soft soil after drainage solidification and the overlying flexible permeable sand cushion layer jointly form the composite pile 10 with higher bearing capacity.
While the foregoing description of the embodiments of the present invention has been presented in conjunction with the drawings, it should be understood that it is not intended to limit the scope of the invention, but rather, it is intended to cover all modifications or variations within the scope of the invention as defined by the claims of the present invention.
Claims (8)
1. The construction device for manufacturing the composite stiffening core pile based on the MICP is characterized by comprising an outer sinking pipe and an inner sinking pipe, wherein the outer sinking pipe and the inner sinking pipe form a double-cylinder structure, and the pipe wall of the outer sinking pipe is of a double-layer structure and is used for supporting and retaining; a cavity is formed between the inner pipe wall and the outer pipe wall of the outer immersed pipe; the cavity is connected with the infusion tube by adopting a thread sleeve head, the infusion tube is used for conveying bacterial liquid and reinforcing liquid into the cavity, and a liquid guide hole is arranged on the tube surface of the inner tube wall of the outer immersed tube; the inner immersed tube is of a single-layer structure and is mainly used for enclosing, and the inner immersed tube is connected with the water pump unit through a water suction tube;
the outer immersed tube and the outer immersed tube are steel immersed tubes, so that a good enclosing effect is achieved, and the overall strength is improved;
the outer immersed tube is connected with the cathode of the power supply to form cathode protection, so that the effect of rust prevention of the immersed tube is realized.
2. The construction device for manufacturing the MICP-based composite pile according to claim 1, wherein the diameter of the liquid guide holes is 14-15 mm, the liquid guide holes are distributed on the pipe surface of the inner pipe wall of the outer sinking pipe in a quincuncial shape, and the area of the liquid guide holes is 15-20% of the area of the pipe surface of the inner pipe wall of the outer sinking pipe.
3. A construction method for manufacturing a construction device of a composite stiffening core pile based on MICP according to claim 1, which is characterized by comprising the following specific steps:
step one: measuring on a flattened field according to design requirements, placing a marking line, and determining pile positions of the stiffening core piles;
step two: determining hole sites according to design requirements, and marking;
step three: drilling by using a drilling machine, drilling a stratum by using a drill rod, keeping a wall protection sleeve along, enabling flushing medium to enter the drilling hole through a channel of the drill rod and a drill bit, and discharging drilling waste residues along the space between the drill rod and the sleeve;
step four: starting a vibrator, sinking the outer immersed tube into the soil for 3.0-5.0 meters, standing for a short time to observe the effect of the immersed tube, observing the condition of surrounding soil, if no bulge exists, continuing the step five, if the bulge exists, suspending the vibrator, and continuing sinking the outer immersed tube into the soil after repairing;
step five: continuously starting the vibrator, sinking the outer sinking pipe to a set depth, and keeping vibrating for 1 minute every 2.0 meters in the sinking process;
step six: repeating the fourth step to the fifth step, and sinking into the inner sinking pipe;
step seven: preparing a pulse-producing enzyme bacterial solution and a strengthening solution which are needed by microorganism mineralization; the pulse-producing enzyme bacterial solution is composed of nutrition salt solution with the concentration of OD600 = 1.5, which is necessary for the vital activity of the armillaria pastoris; the strengthening liquid is prepared by mixing a calcium chloride solution with the concentration of 0.5-1.2 mol/L and a urea solution with the concentration of 0.5-1.2 mol/L; each 100g of nutrient salt solution contains 5.0g of soybean protein pulse, 15g of pancreas protein pulse, 5.0g of sodium chloride and 20g of urea, and the pH value of the nutrient salt solution is 7.3;
step eight: connecting a water suction pump unit into an inner immersed tube, connecting a liquid delivery tube for delivering the pulse enzyme-producing bacterial liquid with the inner wall of an outer immersed tube, opening the water suction pump unit and the liquid delivery tube, and forming a stable seepage field in soil between the inner immersed tube and the outer immersed tube by utilizing the water head difference between the inner immersed tube and the outer immersed tube so that the pulse enzyme-producing bacterial liquid is diffused to the foundation around a drill hole and adsorbed on soil particles;
step nine: connecting the outer immersed tube with a direct current power supply cathode, and connecting the inner immersed tube with a direct current power supply anode; closing a switch of the direct current power supply, forming a direct current electric field between a transfusion tube of a cathode of the power supply and a water suction tube of an anode of the power supply, and cutting off the switch of the direct current power supply after the direct current electric field acts for 4-8 hours; the direct current electric field is applied at the moment that in the attaching stage of the pulse producing enzyme bacteria, the pulse producing enzyme bacteria with negative charges move to the power anode in an electrophoresis mode, so that the pulse producing enzyme bacteria enriched at the near end of the pulse producing enzyme bacteria liquid injection position migrate to the far end of the pulse producing enzyme bacteria liquid injection position, and the redistribution of the pulse producing enzyme bacteria in space is realized;
step ten: cutting off a direct current power supply, standing for 24 hours, connecting a perfusion tube for conveying reinforcing liquid to the inner wall of an outer immersed tube, simultaneously opening a water suction pump unit and the perfusion tube, forming a stable seepage field in soil body between the inner immersed tube and the outer immersed tube by utilizing the water head difference between the inner immersed tube and the outer immersed tube, diffusing the reinforcing liquid to the foundation around a drilling hole, and generating mineralization reaction with pulse producing enzyme bacteria adsorbed on soil body particles to generate calcium carbonate crystals with cementing effect;
step eleven: connecting the outer sinking pipe with a power cathode, and connecting the inner sinking pipe with a power anode; closing a switch of the direct current power supply, forming a direct current electric field between a transfusion tube of a cathode of the power supply and a water suction tube of an anode of the power supply, and cutting off the switch of the direct current power supply after the direct current electric field acts for 4-8 hours; the direct current electric field is applied at the moment that in the reinforcing liquid reaction stage, the negatively charged reinforcing liquid moves to the power anode in an electrophoresis mode, so that the reinforcing liquid enriched at the near end of the reinforcing liquid injection position migrates to the far end of the reinforcing liquid injection position, and the redistribution of the reinforcing liquid in space is realized;
step twelve: repeating the steps ten to eleven until the soil body is reinforced to the design strength;
step thirteen: manufacturing a concrete slurry stirring strength core in the inner immersed tube;
firstly, digging a foundation pit according to the design, and then continuously infusing the prepared concrete slurry which is not subjected to segregation by a conveying pump, and stirring by a stirrer for three times, namely primary spraying, primary stirring or secondary spraying; when the concrete slurry reaches the slurry outlet, spraying concrete slurry 30S at the pile base to enable the slurry to completely reach the pile end, and when the slurry outlet reaches the pile top elevation, stopping lifting by the stirrer, and stirring for a plurality of seconds again to ensure that the pile head of the stiffening core pile is uniform and compact;
step fourteen: after the microbial composite stiffening core pile is formed, a flexible permeable sand cushion layer is paved at the top of a foundation formed by the microbial composite stiffening core pile and soil between piles, a pre-pressing load is applied at the top of the flexible permeable sand cushion layer, so that pore water in the soil between piles is discharged along a drainage channel formed by the sand piles and the flexible permeable sand cushion layer, the soil between piles is solidified, the bearing capacity of the soil between piles is improved, and the microbial composite stiffening core pile, soft soil after drainage solidification and the overlying flexible permeable sand cushion layer form the composite stiffening core pile with high bearing capacity together.
4. A method according to claim 3, wherein in the first step, pile positions of the stiffening piles are spaced apart.
5. The construction method according to claim 3, wherein in the second step, the spacing error between every two holes in the horizontal direction is not more than 50mm, and the spacing error between every two holes in the vertical direction is not more than 100mm; the deflection dimension of the bottom of the hole is not more than 3% of the design length; the depth of the hole is not less than the design length and not more than 1% of the design length.
6. The construction method according to claim 3, wherein in the third step, a drill inclinometer is used to control the direction of drilling, the angle deviation is not more than 3 degrees, and the deviation of the drilled hole is prevented; when dry drilling holes, small augers are used to drill holes.
7. The construction method according to claim 3, wherein the water pump unit is a dry vacuum pump unit or a jet pump unit, the water collecting main pipe in the water pump unit is a steel pipe with the diameter of 75-150 mm, the water collecting main pipe and the inner immersed pipe are connected by adopting a flange, and the strength of the direct current electric field is 0.5-1.0V/cm.
8. The construction method according to claim 3, wherein the concrete slurry is 0.5m higher than the foundation ground when the concrete slurry stirring strength core is manufactured in the inner immersed tube in the step thirteen; when the concrete slurry is stopped to be conveyed due to faults, the stirrer is sunk to the position 0.5m below the slurry stopping point, when slurry is recovered, lifting is performed again, if the shutdown time exceeds 3 hours, the pipeline is cleaned, the concrete slurry is prevented from hardening and blocking the pipeline, and the concrete slurry is cured for 14 days after being infused; the reinforcing depth of the stiffening core pile is not more than 20m, and when the dry construction is used, the reinforcing depth of the stiffening core pile is not more than 15m, the diameter of the inner sinking pipe is not less than 500mm, and the radius of the outer sinking pipe is not less than 1000mm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810456134.2A CN108396736B (en) | 2018-05-14 | 2018-05-14 | Construction device and construction method for manufacturing MICP-based composite stiffening core pile |
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| WO2017133373A1 (en) * | 2016-02-05 | 2017-08-10 | 王继忠 | Small-diameter pile cluster used for pile foundation, and method for construction thereof |
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| GB9122575D0 (en) * | 1991-10-24 | 1991-12-04 | Sloma Robert M | Improvements in or relating to piling |
| JP2001172987A (en) * | 1999-12-16 | 2001-06-26 | Shimizu Corp | Pile foundation structure and its construction method |
| CN102418344B (en) * | 2011-06-17 | 2014-02-19 | 北京荣创科宏岩土工程有限公司 | Injector, drill bit combination structure and combination drilling tool |
| CN103074891B (en) * | 2013-01-29 | 2015-07-15 | 浙江信博城市建设有限公司 | Double-layer plastic sleeve bulk material and concrete stiffness core composite pile and construction method thereof |
| CN204898658U (en) * | 2015-06-24 | 2015-12-23 | 商丘工学院 | Be used for consolidating little biological glue knot sand pile of soft soil foundation |
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| CN106906821A (en) * | 2017-03-09 | 2017-06-30 | 方祥位 | A kind of microorganism sand pile pile-forming apparatus and method |
| CN208395807U (en) * | 2018-05-14 | 2019-01-18 | 海南省水文地质工程地质勘察院 | A kind of constructing device making compound strength core stake |
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| DE2743639A1 (en) * | 1976-09-28 | 1978-03-30 | Neturen Co Ltd | CONCRETE SUPPORTS REINFORCED WITH FLEXIBLE ROD AND PROCESS FOR MANUFACTURING THE SAME |
| WO2017133373A1 (en) * | 2016-02-05 | 2017-08-10 | 王继忠 | Small-diameter pile cluster used for pile foundation, and method for construction thereof |
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