Double-high-pressure-bag type rotary spraying equipment under complex geological conditions and construction technology thereof

Abstract

The invention discloses complex geological condition double-high-pressure-bag type rotary jet grouting equipment and a construction technology thereof, and belongs to the field of rotary jet grouting pile construction equipment. The equipment comprises a drill rod, a bag body, an upper sensor, a lower sensor, a water spraying opening, a slurry spraying opening and an air spraying opening; the bag body annularly wraps the surface of the drill rod, the bag body is fixed on the drill rod through the fastening sleeve, the upper sensor is installed in a gap between the bag body and the drill rod, the lower sensor is embedded in the surface of the drill rod, and the water spraying opening, the slurry spraying opening and the air spraying opening are all formed in the drill rod. The in-situ soil body in the pile diameter is firstly cut through high-pressure water sprayed out of the water spraying opening, then cutting is further conducted through high-pressure grout, and the requirement for the pile diameter is met; the bag body is always unfolded to ensure that slurry at the lower part of the bag body is always in a sealed under-pressure state, so that the ability of the slurry to permeate to the periphery is improved, and the bag body isolates the water injection port and the slurry spraying port, so that media sprayed by the water injection port and the slurry spraying port do not influence each other.

Description

Technical Field

[0001] The invention belongs to the field of rotary jet grouting pile construction equipment, and in particular relates to double high-pressure capsule type rotary jet grouting equipment under complex geological conditions and a construction process thereof. Background Art

[0002] Jet grouting is a commonly used foundation treatment method, usually used in soft soil areas and foundation projects that need to be reinforced. Jet grouting is a method of spraying cement slurry underground through a rotating nozzle, breaking up the in-situ soil with high-pressure slurry and evenly mixing it with the in-situ soil to form a reinforced pile.

[0003] During the construction of rotary jet piles, the diffusion and distribution state of the slurry can be divided into the following stages: the initial diffusion stage, when the injection process begins, the slurry first breaks the in-situ soil from the nozzle, and the slurry presents a strong radial diffusion state; the ground-breaking boundary stage, as the injection continues, the momentum of the slurry gradually decreases, and the slurry does not have the ability to break the ground; the seepage diffusion stage, after the slurry reaches the ground-breaking limit boundary, the slurry gradually migrates to the small channels connected to the boundary through the pressure in the hole, forming a weak reinforcement area.

[0004] At present, during the construction of jet grouting piles, it is difficult to achieve uniform pile diameter due to the influence of different strata. Even when constructing in hard clay layers, the designed pile diameter cannot be reached, and thus the design requirements cannot be met. For foundation reinforcement, the farther the seepage diffusion stage is, the better. However, the current jet grouting technology cannot diffuse the slurry far beyond the designed pile diameter range. Based on this, the present invention proposes a double high-pressure capsule jet grouting equipment for complex geological conditions and its construction process. Summary of the invention

[0005] In view of the above technical problems existing in the prior art, the present invention proposes a double high-pressure capsule type rotary grouting equipment and its construction process for complex geological conditions, which overcomes the shortcomings of the prior art. The high-pressure water sprayed from the water spray port first cuts the in-situ soil within the pile diameter, and then further cuts it through the high-pressure slurry, ensuring the pile diameter requirements; the capsule separates the more water in the upper part from the lower part, and the slurry sprayed from the grouting port will not be diluted by the upper water, so the grouting effect is better, and the slurry sprayed from the grouting port is completely retained in the lower part of the capsule; the capsule is always unfolded to ensure that the slurry in the lower part of the capsule is always in a sealed and pressurized state, which increases the ability of the slurry to penetrate into the surrounding area, and the capsule isolates the water spray port and the grouting port, so that the media sprayed from the two will not affect each other.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: The double high-pressure capsule type rotary grouting equipment for complex geological conditions is characterized in that it comprises a drill rod, a capsule, an upper sensor, a lower sensor, a water spray port, a grouting port and an air jet port; the capsule is a double-layer bag-like structure, the capsule is annularly wrapped on the surface of the drill rod, the end of the capsule away from the drill tip is fixed on the drill rod through a fastening sleeve, the air inlet of the capsule is arranged on one side of the fixed end, when the capsule expands, a layer close to the drill rod is limited by the drill rod and squeezed, a layer of the capsule away from the drill rod is limited by surrounding obstacles, an upper sensor is installed in the gap between the capsule and the drill rod, the lower sensor is embedded in the surface of the drill rod, the outer edge surface of the lower sensor is flush with the outer surface of the drill rod, the lower sensor is installed at a position close to the drill tip, the water spray port, the grouting port and the air jet port are all arranged on the drill rod, the water spray port is arranged at the drill rod at the upper part of the capsule, the grouting port is arranged at the lower part of the capsule, at the drill rod close to the drill tip, the air jet port is arranged at the lower part of the capsule, at the drill rod above the grouting port, and the jetting direction of the air jet port is different from that of the grouting port.

[0007] Preferably, the material of the bladder is a soft composite film or steel, the thickness of the bladder is 0.1mm-0.5mm, the upper part of the bladder is limited, and the lower part is free. When the bladder is inflated, the free end moves up and the diameter of the bladder increases. When the bladder is deflated, the free end moves down and the diameter of the bladder decreases.

[0008] Preferably, the water spray outlet is 20cm~40cm away from the upper part of the capsule, the water spray outlet is a composite water spray outlet, and gas and water are sprayed simultaneously. The water body is sprayed in a columnar shape, and the gas is sprayed around the periphery of the water body. The pressure range of the water spray is 30MPa~100MPa, and the pressure range of the gas spray is 0.7MPa~1.5MPa.

[0009] Preferably, the air jet is 20 cm to 40 cm away from the lowermost state of the free end of the capsule.

[0010] Preferably, the pressure range of the spraying port is 5MPa~40MPa.

[0011] The construction process of the double high-pressure capsule type rotary grouting equipment under complex geological conditions is characterized in that when the double high-pressure capsule type rotary grouting equipment under complex geological conditions is used for construction, the operation and control are carried out according to the following method: Step 1: Drilling holes Use the drilling equipment to drill holes at the designed pile positions to ensure that the verticality and depth of the holes meet the design requirements; Step 2: Lower the jet jet drill rod By adding drill pipes, the injection position reaches the designed depth; Step 3: Spray-jet drilling construction (1) Pressure setting: Set the water spraying pressure of the water spraying nozzle, the grouting pressure of the grouting nozzle, and the monitoring pressure of the lower sensor according to the designed pile diameter; (2) Re-spraying at the pile end: When the drill is first lifted, slurry is sprayed from the spray nozzle. The slurry pressure is 3MPa~5MPa higher than the designed spraying pressure of the spray nozzle. The drill is lifted at the set lifting speed. When it is lifted to a position of 1m~2m, the slurry spraying is stopped and the drill is lowered to the designed depth of the pile end. (3) Balloon expansion: Inflate the balloon and stop inflating when the data monitored by the upper sensor increases sharply; (4) Drill lifting construction: Start to spray different media from the water jet and shotcrete nozzles at the designed injection pressure, and lift the drill at the designed drill lifting speed. During the drill lifting process, continuously monitor the value changes of the upper sensor and the lower sensor; (5) High-pressure auxiliary grouting: When the displayed value of the lower sensor is less than the set value, high-pressure gas is continuously sprayed from the jet nozzle until the displayed value of the lower sensor is equal to the set value; (6) Bladder adjustment: When the displayed value of the upper sensor increases significantly and the drilling force of the jet grouting drill increases suddenly, the gas in the bladder is released, the diameter of the bladder is reduced, and the drill rod is continuously lifted. After the drilling force of the jet grouting drill stabilizes, the bladder is inflated. When the monitoring data of the upper sensor increases sharply, the inflation is stopped. (7) Process adjustment: Constantly monitor the values ​​of the upper and lower sensors, and use (5) and (6) to make adjustments in real time in combination with the lifting force of the drilling rig until the designed pile top elevation is reached, stop the medium injection from all nozzles, and release the gas in the bladder; Step 4: Complete the construction The drill rod and bladder were flushed, and the mud around the site was treated to complete the construction.

[0012] Beneficial technical effects brought by the present invention: The high-pressure water sprayed from the water nozzle first cuts the in-situ soil within the pile diameter, and then further cuts it through the high-pressure slurry, ensuring the pile diameter requirements; the capsule separates the more water in the upper part from the lower part, and the slurry sprayed from the spray nozzle will not be diluted by the upper water, so the grouting effect is better, and the slurry sprayed from the spray nozzle remains completely in the lower part of the capsule; the capsule is always expanded to ensure that the slurry in the lower part of the capsule is always in a sealed and pressurized state, which increases the ability of the slurry to penetrate into the surrounding area, and the capsule isolates the water nozzle and the spray nozzle, so the media sprayed from the two will not affect each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall structure of the double high-pressure capsule type jet grouting equipment for complex geological conditions and its construction process of the present invention; Among them, 1-drill rod, 2-bladder, 3-upper sensor, 4-lower sensor, 5-water nozzle, 6-grouting nozzle, 7-air nozzle. DETAILED DESCRIPTION

[0014] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments: the up and down positional relationships described herein are all up and down in physical structure, that is, the drill tip is the lower end, and the capsule 2 is at the upper end of the drill tip. Other structures refer to this positional relationship. Embodiment 1:

[0015] like Figure 1 As shown, the double high-pressure capsule type rotary grouting equipment for complex geological conditions includes a drill rod 1, a capsule 2, an upper sensor 3, a lower sensor 4, a water spray port 5, a grouting port 6, and an air jet port 7; the capsule 2 is a double-layer bag-like structure, the capsule 2 is annularly wrapped on the surface of the drill rod 1, the end of the capsule 2 away from the drill tip is fixed to the drill rod 1 through a fastening sleeve, the air inlet of the capsule 2 is arranged on one side of the fixed end, when the capsule 2 expands, a layer close to the drill rod 1 is limited by the drill rod 1 and squeezed, and a layer of the capsule 2 away from the drill rod 1 is limited by surrounding obstacles, and when the capsule 2 and the drill rod 1 are inflated, the air inlet of the capsule 2 is arranged on the fixed end side. An upper sensor 3 is installed in the gap between the drill rods 1, and the lower sensor 4 is embedded in the surface of the drill rod 1. The outer edge of the lower sensor 4 is flush with the outer surface of the drill rod 1, and the lower sensor 4 is installed at a position close to the drill tip. The water jet port 5, the shotcrete port 6, and the air jet port 7 are all arranged on the drill rod 1. The water jet port 5 is arranged at the drill rod 1 at the upper part of the capsule 2, the shotcrete port 6 is arranged at the lower part of the capsule 2, at the drill rod 1 close to the drill tip, and the air jet port 7 is arranged at the lower part of the capsule 2, at the drill rod 1 above the shotcrete port 6, and the injection direction of the air jet port 7 is different from that of the shotcrete port 6.

[0016] Preferably, the material of the bladder 2 is a soft composite film or steel, the thickness of the bladder 2 is 0.1mm-0.5mm, the upper part of the bladder 2 is limited, and the lower part is free. When the bladder 2 is inflated, the free end moves up and the diameter of the bladder 2 increases. When the bladder 2 is deflated, the free end moves down and the diameter of the bladder 2 decreases.

[0017] Preferably, the water spray port 5 is 20 cm to 40 cm away from the upper part of the capsule 2, and is a composite water spray port 5, which sprays gas and water simultaneously, the water body is sprayed in a columnar shape, and the gas is sprayed around the periphery of the water body. The pressure range of the water spray is 30 MPa to 100 MPa, and the pressure range of the gas spray is 0.7 MPa to 1.5 MPa.

[0018] Preferably, the air jet 7 is 20 cm to 40 cm away from the lowermost state of the free end of the capsule 2 .

[0019] Preferably, the pressure range of the spraying port 6 is 5MPa~40MPa.

[0020] The construction technology of double high-pressure capsule jet grouting equipment under complex geological conditions. When using double high-pressure capsule jet grouting equipment under complex geological conditions for construction, the operation and control shall be carried out in accordance with the following methods: Step 1: Drilling holes Use the drilling equipment to drill holes at the designed pile positions to ensure that the verticality and depth of the holes meet the design requirements; Step 2: Lower the jet jet drill rod 1 The injection position reaches the designed depth by adding drill pipe 1; Step 3: Spray-jet drilling construction (1) Pressure setting: Set the water spraying pressure of the water spraying port 5, the grouting pressure of the grouting port 6, and the monitoring pressure of the lower sensor 4 according to the designed pile diameter; (2) Re-spraying at the pile end: When the drill is first lifted, slurry is sprayed from the spraying port 6. The slurry pressure is 3 MPa to 5 MPa higher than the designed spraying pressure of the spraying port 5. The drill is lifted at the set lifting speed. When it is lifted to a position of 1 m to 2 m, the slurry spraying is stopped and the drill is lowered to the designed depth of the pile end. (3) Expanding the bladder 2: Inflate the bladder 2 and stop inflating when the data monitored by the upper sensor 3 increases sharply; (4) Drill lifting construction: Start to spray different media from the water jet port 5 and the shotcrete jet port 6 at the designed injection pressure, and lift the drill at the designed drill lifting speed. During the drill lifting process, continuously monitor the value changes of the upper sensor 3 and the lower sensor 4; (5) High-pressure auxiliary grouting: When the displayed value of the lower sensor 4 is less than the set value, high-pressure gas is continuously sprayed from the jet nozzle 7 until the displayed value of the lower sensor 4 is equal to the set value; (6) Adjustment of the bladder 2: When the displayed value of the upper sensor 3 increases significantly and the drilling force of the jet grouting drill increases suddenly, the gas in the bladder 2 is released to reduce the diameter of the bladder 2 and continuously lift the drill rod 1. When the drilling force of the jet grouting drill stabilizes, the bladder 2 is inflated and the inflation is stopped when the monitoring data of the upper sensor 3 increases sharply. (7) Process adjustment: constantly monitor the values ​​of the upper sensor 3 and the lower sensor 4, and make adjustments in real time using steps (5) and (6) in combination with the lifting force of the drilling rig until the designed pile top elevation is reached, stop the medium injection from all nozzles, and release the gas in the bladder 2; Step 4: Complete the construction The drill pipe 1 and the bladder are flushed, the mud around the site is treated, and the construction is completed. Embodiment 2:

[0021] When the double high-pressure capsule type rotary spraying equipment of the present invention is used for construction, the specific steps are as follows: like Figure 1As shown, the double high-pressure capsule type rotary grouting equipment for complex geological conditions includes a drill rod 1, a capsule 2, an upper sensor 3, a lower sensor 4, a water spray port 5, a grouting port 6, and an air jet port 7; the capsule 2 is a double-layer bag-like structure, the capsule 2 is annularly wrapped on the surface of the drill rod 1, the end of the capsule 2 away from the drill tip is fixed to the drill rod 1 through a fastening sleeve, the air inlet of the capsule 2 is arranged on one side of the fixed end, when the capsule 2 expands, a layer close to the drill rod 1 is limited by the drill rod 1 and squeezed, and a layer of the capsule 2 away from the drill rod 1 is limited by surrounding obstacles, and the capsule 2 is similar to a balloon, but is in a hollow state. The annular balloon has a hole in the middle for the drill rod 1. When the balloon 2 is inflated, the free boundary gradually expands outward, and at the same time, the free end of the lower end moves upward. The layer of the balloon 2 close to the drill rod 1 will squeeze the drill rod 1, but the squeezing effect is not obvious. When the other layer of the balloon 2 hits the surrounding soil and cannot move further, the volume of the balloon 2 no longer changes. As the gas is filled in, the squeezing of the drill rod 1 by the balloon 2 will increase sharply. An upper sensor 3 is installed in the gap between the balloon 2 and the drill rod 1. The value of the upper sensor 3 will increase significantly, and it can be determined that the balloon 2 has reached the boundary of the pile body.

[0022] The lower sensor 4 is embedded in the surface of the drill pipe 1, and the outer edge of the lower sensor 4 is flush with the outer surface of the drill pipe 1. The lower sensor 4 is installed near the drill tip. The lower sensor 4 mainly monitors the slurry after mixing to ensure that the cavity in the lower part of the bladder 2 is always maintained at a higher pressure, which is conducive to the outward diffusion of the slurry.

[0023] The water jet 5, the grouting port 6, and the air jet 7 are all arranged on the drill rod 1. The water jet 5 is arranged at the drill rod 1 at the upper part of the capsule 2, the grouting port 6 is arranged at the lower part of the capsule 2, at the drill rod 1 near the drill tip, and the air jet 7 is arranged at the lower part of the capsule 2, at the drill rod 1 above the grouting port 6, and the jetting directions of the air jet 7 and the grouting port 6 are different. The water jet 5 and the grouting port 6 are arranged at the upper and lower parts of the capsule 2, respectively, mainly to avoid turbulence during the injection process of the two.

[0024] Preferably, the material of the bladder 2 is a soft composite film or steel, and the thickness of the bladder 2 is 0.1mm-0.5mm. The bladder 2 is made of steel and is relatively thin. One reason is to increase the rigidity of the bladder 2 to prevent the presence of rocks in the soil from damaging the bladder 2, and the other reason is that it is relatively thin and can be smoothly unfolded and retracted. The bladder 2 has an upper limit and a lower free end. When the bladder 2 is inflated, the free end moves upward, and the diameter of the bladder 2 increases. When the bladder 2 is deflated, the free end moves downward, and the diameter of the bladder 2 decreases.

[0025] Preferably, the water jet 5 is 20 cm to 40 cm away from the upper part of the capsule 2, and the water jet 5 is a composite water jet 5, which simultaneously jets gas and water, the water body is jetted in a columnar shape, and the gas is jetted around the periphery of the water body, the water jet pressure range is 30 MPa to 100 MPa, and the gas jet pressure range is 0.7 MPa to 1.5 MPa. In order to increase the cutting ability of water, the water energy is preserved by using the air-in-water method.

[0026] Preferably, the air jet port 7 is 20 cm to 40 cm away from the free end of the capsule 2 at the lowest position. The certain distance is to reduce the influence of the gas on the capsule 2 .

[0027] Preferably, the pressure range of the spraying port 6 is 5MPa~40MPa.

[0028] The construction process of the double high-pressure capsule type rotary grouting equipment under complex geological conditions is characterized in that when the double high-pressure capsule type rotary grouting equipment under complex geological conditions is used for construction, the operation and control are carried out according to the following method: Step 1: Drilling holes Use the drilling equipment to drill holes at the designed pile positions to ensure that the verticality and depth of the holes meet the design requirements; Step 2: Lower the jet jet drill rod 1 The injection position reaches the designed depth by adding drill pipe 1; Step 3: Spray-jet drilling construction (1) Pressure setting: Set the water spraying pressure of the water spraying port 5, the grouting pressure of the grouting port 6, and the monitoring pressure of the lower sensor 4 according to the designed pile diameter; (2) Re-spraying at the pile end: When the drill is first lifted, slurry is sprayed from the spraying port 6. The slurry pressure is 3 MPa to 5 MPa higher than the designed spraying pressure of the spraying port 5. The drill is lifted at the set lifting speed. When it is lifted to a position of 1 m to 2 m, the slurry spraying is stopped and the drill is lowered to the designed depth of the pile end. (3) Expanding the bladder 2: Inflate the bladder 2 and stop inflating when the data monitored by the upper sensor 3 increases sharply; (4) Drill lifting construction: Start to spray different media from the water jet port 5 and the shotcrete jet port 6 at the designed injection pressure, and lift the drill at the designed drill lifting speed. During the drill lifting process, continuously monitor the value changes of the upper sensor 3 and the lower sensor 4; (5) High-pressure auxiliary grouting: When the displayed value of the lower sensor 4 is less than the set value, high-pressure gas is continuously sprayed from the jet nozzle 7 until the displayed value of the lower sensor 4 is equal to the set value; (6) Adjustment of the bladder 2: When the displayed value of the upper sensor 3 increases significantly and the drilling force of the jet grouting drill increases suddenly, the gas in the bladder 2 is released to reduce the diameter of the bladder 2 and continuously lift the drill rod 1. When the drilling force of the jet grouting drill stabilizes, the bladder 2 is inflated and the inflation is stopped when the monitoring data of the upper sensor 3 increases sharply. (7) Process adjustment: constantly monitor the values ​​of the upper sensor 3 and the lower sensor 4, and make adjustments in real time using steps (5) and (6) in combination with the lifting force of the drilling rig until the designed pile top elevation is reached, stop the medium injection from all nozzles, and release the gas in the bladder 2; Step 4: Complete the construction The drill pipe 1 and the bladder are flushed, the mud around the site is treated, and the construction is completed.

[0029] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention also fall within the protection scope of the present invention.

Claims

1. Double high-pressure capsule jet grouting equipment for complex geological conditions, characterized by: The invention comprises a drill rod, a bladder, an upper sensor, a lower sensor, a water jet, a grouting jet and an air jet. The bladder is a double-layer bag-like structure, which is annularly wrapped on the surface of the drill rod, and one end of the bladder away from the drill tip is fixed on the drill rod by a fastening sleeve. The air inlet of the bladder is arranged on one side of the fixed end. When the bladder expands, a layer close to the drill rod is limited by the drill rod and squeezed, and a layer of the bladder away from the drill rod is limited by surrounding obstacles. The upper sensor is installed in the gap between the bladder and the drill rod, and the lower sensor is embedded in the surface of the drill rod. The outer edge surface of the lower sensor is flush with the outer surface of the drill rod. The lower sensor is installed at a position close to the drill tip. The water jet, the grouting jet and the air jet are all arranged on the drill rod. The water jet is arranged at the drill rod at the upper part of the bladder, the grouting jet is arranged at the lower part of the bladder, at the drill rod close to the drill tip, and the air jet is arranged at the lower part of the bladder, at the drill rod above the grouting jet, and the jet directions of the air jet and the grouting jet are different.

2. The double high-pressure capsule type jet grouting equipment for complex geological conditions according to claim 1 is characterized by: The material of the sac is a soft composite film or steel, the thickness of the sac is 0.5mm-1.5mm, the upper part of the sac is limited, and the lower part is free. When the sac is inflated, the free end moves up and the diameter of the sac increases. When the sac is deflated, the free end moves down and the diameter of the sac decreases.

3. The double high-pressure capsule type jet grouting equipment for complex geological conditions according to claim 1 is characterized by: The water spray outlet is 20cm~40cm away from the upper part of the capsule. The water spray outlet is a composite water spray outlet, which sprays gas and water at the same time. The water body is sprayed in a columnar shape, and the gas is sprayed around the periphery of the water body. The pressure range of the water spray is 30MPa~100MPa, and the pressure range of the gas spray is 0.7MPa~1.5MPa.

4. The double high-pressure capsule jet grouting equipment for complex geological conditions according to claim 1 is characterized by: The air jet is 20 cm to 40 cm away from the free end of the capsule at the lowest position.

5. The double high-pressure capsule jet grouting equipment for complex geological conditions according to claim 1 is characterized by: The pressure range of the spraying port is 5MPa~40MPa.

6. The construction process of double high-pressure capsule jet grouting equipment in complex geological conditions is characterized by: When the double high-pressure capsule jet grouting equipment for complex geological conditions as claimed in claim 1 is used for construction, the operation and control are carried out in accordance with the following method: Step 1: Drilling holes Use the drilling equipment to drill holes at the designed pile positions to ensure that the verticality and depth of the drilling holes meet the design requirements; Step 2: Lower the jet jet drill rod By adding drill pipes, the injection position reaches the designed depth; Step 3: Spray-jet drilling construction (1) Pressure setting: Set the water spraying pressure of the water spraying nozzle, the grouting pressure of the grouting nozzle, and the monitoring pressure of the lower sensor according to the designed pile diameter; (2) Re-spraying at the pile end: When the drill is first lifted, slurry is sprayed from the spray nozzle. The slurry pressure is 3MPa~5MPa higher than the designed spraying pressure of the spray nozzle. The drill is lifted at the set lifting speed. When it is lifted to a position of 1m~2m, the slurry spraying is stopped and the drill is lowered to the designed depth of the pile end. (3) Balloon expansion: Inflate the balloon and stop inflating when the data monitored by the upper sensor increases sharply; (4) Drill lifting construction: Start to spray different media from the water jet and shotcrete nozzles at the designed injection pressure, and lift the drill at the designed drill lifting speed. During the drill lifting process, continuously monitor the value changes of the upper sensor and the lower sensor; (5) High-pressure auxiliary grouting: When the displayed value of the lower sensor is less than the set value, high-pressure gas is continuously sprayed from the jet nozzle until the displayed value of the lower sensor is equal to the set value; (6) Bladder adjustment: When the displayed value of the upper sensor increases significantly and the drilling force of the jet grouting drill increases suddenly, the gas in the bladder is released, the diameter of the bladder is reduced, and the drill rod is continuously lifted. After the drilling force of the jet grouting drill stabilizes, the bladder is inflated. When the monitoring data of the upper sensor increases sharply, the inflation is stopped. (7) Process adjustment: Constantly monitor the values ​​of the upper and lower sensors, and use (5) and (6) to make adjustments in real time in combination with the lifting force of the drilling rig until the designed pile top elevation is reached, stop the medium injection from all nozzles, and release the gas in the bladder; Step 4: Complete the construction The drill rod and bladder were flushed, and the mud around the site was treated to complete the construction.

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