Multi-channel powder spraying and stirring pile drilling machine equipment and construction method

Abstract

This invention relates to the field of construction drilling equipment technology, specifically a multi-channel powder jet mixing pile drilling rig and construction method. The equipment includes a drilling rig body, a material supply backend, and a control module. The control module, through real-time monitoring and control of various electrical switches, sensors, and instruments, enables a continuous, uniform, and quantitative supply of high-pressure gas and curing agent powder to the drilling rig's gas-material pipeline. The gas-solid two-phase mixed compressed fluid and high-pressure airflow enter the focusing area at the bottom of the multi-layer shear mixing drill bit through the gas-material channel and airflow channel of the drill bit, respectively. The two high-pressure fluids become more uniform after reflection, mixing, and gasification within the focusing area. High-pressure jetting and mixing of the foundation soil are achieved through the mixing blades and nozzles at both ends of the multi-layer shear mixing drill bit. The staggered shearing and mixing action of the multi-layer shear mixing drill bit ensures thorough mixing of the curing agent powder with the undisturbed soil, forming a large-diameter, high-quality powder jet mixing pile.

Description

Technical Field

[0001] This invention relates to the technical field of drilling equipment for the construction of jet grouting piles in geotechnical engineering, and more specifically to a multi-channel jet grouting pile drilling rig and construction method. Background Technology

[0002] Large areas of soft soil exist within my country's territory, mainly distributed in coastal provinces and cities. In addition, soft soil is also found in inland lake and marshland areas, such as the lacustrine sedimentary layers in Dongting Lake, Hongze Lake, and Taihu Lake, as well as the riverbank sedimentary layers in the middle and lower reaches of major rivers.

[0003] In these regions, soft soil is widespread, posing significant challenges to engineering and road construction technologies. For example, in the construction of highways, railways, and bridges, foundation treatment in soft soil areas is a crucial technical aspect, requiring foundation reinforcement, drainage consolidation, and other technical measures to ensure the safety and stability of the project. The powder jet grouting method uses cement or lime powder as a reinforcing material. Specialized dry-jet grouting equipment uses compressed air to spray the powder reinforcing material into the foundation soil in a mist-like manner. The rotating drill blades forcefully mix the powder reinforcing material with the in-situ foundation soil, forming piles with strong integrity, good water stability, and high bearing capacity in a short time. Powder jet grouting construction technology offers advantages such as low vibration, no pollution, high speed, simple construction machinery, high construction efficiency, and low project cost.

[0004] For the construction technology of jet grouting piles, a series of unidirectional jet grouting pile drilling rigs have been developed both domestically and internationally. However, the following technical problems still need to be solved in the construction of existing drilling rigs:

[0005] 1. The construction of powder jet grouting piles has high requirements and requires professional technicians to operate. Since the material supply speed and quantity are usually manually controlled by the construction personnel, the construction quality is difficult to meet the design requirements, and even pipe blockage and material interruption may occur.

[0006] 2. Currently, the diameter of powder spraying and mixing piles is generally 500mm and the length is less than 15m, and large-diameter powder spraying and mixing piles cannot be constructed. When the pile diameter and pile length exceed the above indicators, engineering accidents such as insufficient pile diameter and uneven mixing of curing agent are prone to occur during construction.

[0007] 3. Powder jet mixing drill bits usually adopt a unidirectional mixing drill bit structure similar to wet jet mixing piles. However, this drill bit structure cannot guarantee that the dry powder of the curing agent is fully and evenly mixed in the foundation soil, resulting in poor pile quality.

[0008] 4. When gas-solid two-phase fluids are transported via pneumatic conveying through pipelines, pipe blockage and insufficient spray radius often occur when the pressure of the high-pressure gas in the pipeline is insufficient or the depth of the powder nozzle is subjected to excessive ground pressure. Summary of the Invention

[0009] Addressing the characteristics and technical challenges of existing powder jet grouting pile construction equipment, this invention proposes a multi-channel powder jet grouting pile drilling rig and construction method. The multi-layer shearing drill bit enables staggered shearing and mixing of the solidified soil, achieving uniform mixing. Simultaneously, the concave focusing structure within the drill bit utilizes high-pressure airflow and gas-solid two-phase flow to impact and reflect the jetting onto the focusing concave surface, generating secondary gasification, significantly improving the uniformity of powder jet grouting pile mixing and pile strength. The intelligent monitoring and control system employed in the drilling rig effectively controls the material supply backend, ensuring a continuous and stable supply of curing agent powder during construction, thereby improving the construction quality of the powder jet grouting pile. Furthermore, the focusing concave surface is made of hard alloy or ceramic materials, ensuring its structural strength and service life.

[0010] To achieve the objectives of this invention, the following technical solutions are adopted:

[0011] A multi-channel powder jet grouting pile drilling rig includes a drilling rig body, a material supply backend, and a control module. The drilling rig body includes a drill rod and a multi-layer shear mixing drill bit. The drill rod contains at least a gas-material channel and an airflow channel. The multi-layer shear mixing drill bit is connected to the bottom of the drill rod, and a focusing area is provided at the bottom of the drill bit. The focusing area is connected to the discharge end of both the gas-material channel and the airflow channel. The bottom of the multi-layer shear mixing drill bit also has a discharge nozzle connected to the focusing area. The material supply backend and the control module... The control module connects to the material supply backend and controls the material supply and spraying. The curing agent powder is continuously and evenly supplied to the main body of the drilling rig through the gas pipeline in the material supply backend, and high-pressure gas is continuously supplied to the main body of the drilling rig through the gas pipeline in the material supply backend. The curing agent powder and high-pressure gas are transported to the focusing area at the bottom of the multi-layer shear mixing drill bit through the gas channel and air flow channel in the drill rod, respectively. In the focusing area, the material is mixed and vaporized by focusing reflection to form a uniform mixture, which is then sprayed out from the discharge nozzle of the multi-layer shear mixing drill bit.

[0012] Preferably, the drill rod includes an outer stirring rod and an inner stirring rod; the inner stirring rod is rotatably connected inside the outer stirring rod, and the gas-material channel and the airflow channel are fixedly arranged side by side inside the inner stirring rod.

[0013] Preferably, the drill rod includes an outer stirring rod and an inner stirring rod; the inner stirring rod is rotatably connected inside the outer stirring rod, the gas-material channel is fixedly arranged on the central axis of the inner stirring rod, the annular gap between the gas-material channel and the inner stirring rod forms the airflow channel, and the gas-material channel is fixed by a three-rib support frame.

[0014] Preferably, the drill rod includes an outer stirring rod and an inner stirring rod; the inner stirring rod is rotatably connected inside the outer stirring rod, the gas-material channel is disposed inside the inner stirring rod, and the annular gap between the outer stirring rod and the inner stirring rod forms the airflow channel.

[0015] Preferably, the multi-layer shear mixing drill bit includes a mixing frame, a first mixing blade, a second mixing blade, and a tunneling drill bit; the upper end of the mixing frame is fixedly connected to the outer mixing rod, and the lower end of the mixing frame is rotatably connected to the inner mixing rod through a sliding sleeve; the first mixing blade is fixedly connected in layers to the inner side of the mixing frame; the second mixing blade is fixedly connected in layers to the inner mixing rod inside the mixing frame, and the first and second mixing blades are staggered and spaced apart and do not interfere with each other; the outer mixing rod drives the mixing frame and the first mixing blade to rotate, and the inner mixing rod drives the second mixing blade to rotate; the tunneling drill bit is fixedly connected to the bottom of the inner mixing rod, the focusing area is set inside the tunneling drill bit, and the discharge nozzle is set on the outer peripheral wall of the tunneling drill bit.

[0016] Preferably, a flow guide joint is provided between the tunneling drill bit and the bottom of the inner mixing rod. The flow guide joint is provided with a first flow guide channel communicating with the gas material channel and a second flow guide channel communicating with the air flow channel. The lower ends of the first flow guide channel and the lower ends of the second flow guide channel are both flared structures.

[0017] Preferably, the multi-layer shear mixing drill bit has a focusing cavity at its bottom; a focusing element is provided at the bottom of the focusing cavity; the top surface of the focusing element has an upward-opening focusing concave surface, and the focusing area is formed between the focusing concave surface and the material outlet end of the gas-material channel and the air outlet end of the airflow channel.

[0018] Preferably, the discharge nozzle includes a distal nozzle and a proximal nozzle. The distal nozzle is disposed on one side wall of the tunneling drill bit through a nozzle guide, and the proximal nozzle is disposed on the side wall of the tunneling drill bit opposite to the distal nozzle. The distal nozzle and the proximal nozzle are horizontally aligned, and the focal point of the focusing concave surface is located below the horizontal line of the distal nozzle and the proximal nozzle.

[0019] Preferably, the drilling rig body also includes a tower mast, a tie rod, an equipment platform, a drive unit, and a traveling unit. The tower mast is vertically mounted on the equipment platform, and the tie rod fixes the tower mast to the equipment platform. The drive unit is suspended above the tower mast and uses a pulley system on the top of the tower mast to drive the lowering and raising of the drill rod. The traveling unit is located at the bottom of the equipment platform. The drive unit includes a power mechanism and a rotary joint. The power mechanism is connected to the top of the drill rod through the rotary joint and provides rotational torque to the drill rod. The rotary joint is provided with a feed inlet and an air inlet. The feed inlet is connected to the air-material channel on the drill rod, and the air inlet is connected to the airflow channel on the drill rod. The feeding backend includes a high-pressure tank, air compressor A, air compressor B, a jetting system, an air storage tank, and a refrigerated dryer. The high-pressure tank contains curing agent powder, which is then conveyed by a screw conveyor to stabilize the curing agent powder according to set parameters. The curing agent powder is uniformly transported to the injection system at the bottom of the tank. High-pressure gas generated by air compressor A is thoroughly mixed with the curing agent powder within the injection system to form a gas-solid two-phase flow, which is then transported through the gas-material pipeline. The gas-material pipeline is connected to the feed inlet on the main body of the drilling rig to supply the curing agent powder. Simultaneously, a vertical booster pipeline supplied by a branch of air compressor A is added to the vertically ascending section of the gas-material pipeline. An additional air compressor B is added to the feeding backend, connected to the air inlet on the main body of the drilling rig via an air pipeline to supply high-pressure gas. The control module is responsible for monitoring, controlling, and operating the entire feeding backend equipment. Through the PLC measurement and control program of the control module, the pressure inside the high-pressure tank is measured and controlled, as are the designed rotation speed and designed curing agent powder discharge rate of the screw conveyor. Effective measurement and control of various switching valves, pressure gauges, regulating valves, and flow meters in the feeding backend are also implemented to continuously, stably, quantitatively, and uniformly inject curing agent powder into the foundation soil through the gas-material pipeline, gas-material channel, and gas-material nozzle.

[0020] A construction process for a multi-channel jet grouting pile drilling rig, using the aforementioned multi-channel jet grouting pile drilling rig, includes the following steps:

[0021] S1. Before construction begins, the drilling rig body uses the positioning system to accurately align the multi-layer shear mixing drill bit with the pile position to be constructed. The electronic leveling instrument is used to adjust each hydraulic outrigger to keep the verticality of the tower mast and drill rod within 1.5%. The required curing agent powder is injected into the high-pressure tank and all feed and exhaust switches on the high-pressure tank are closed.

[0022] S2. Turn on air compressor A to supply air, and ensure that the air supply pipeline, air supply channel and vertical pressurization pipeline are unobstructed according to the planned air supply pressure and air supply volume. At the same time, turn on air compressor B to supply air to the air pipeline and air flow channel to provide high-pressure gas for the secondary gasification of the curing agent powder inside the focusing chamber.

[0023] S3. During the drilling and mixing stage of the drill bit descending, the drill bit descends at a set speed controlled by pulleys and a winch. The drive unit rotates the outer and inner mixing rods in opposite directions, causing the first and second mixing blades of the multi-layer shear mixing drill bit to rotate and mix the foundation soil at a set speed. Once the multi-layer shear mixing drill bit enters the soil, the spiral conveyor in the high-pressure tank is immediately activated to stably and quantitatively supply curing agent powder to the jetting system. Driven by high-pressure gas, the curing agent powder enters the focusing chamber of the drilling bit through the gas pipeline and gas channel, and then enters the focusing chamber through the gas pipeline and airflow channel, providing favorable conditions for secondary gasification of the curing agent powder inside the focusing chamber. After secondary mixing and gasification, the uniformly mixed curing agent powder is jetted and mixed into the foundation soil through the far-end and near-end nozzles. Material supply stops when the design pile bottom elevation is reached.

[0024] S4. During the upward rotation and mixing stage of the drill bit, the outer mixing rod and the inner mixing rod rotate in opposite directions to lift the drill rod upward at the set lifting speed. During this process, a small amount of high-pressure gas is continuously sprayed through the nozzle to ensure that the nozzle is not blocked by the soil until the multi-layer shear mixing drill bit is lifted out of the ground and the gas supply is stopped. At this time, the construction of the powder jet mixing pile ends.

[0025] S5. Move the machine to the next new pile location and repeat the above process steps to construct the next powder jet grouting pile.

[0026] In summary, the beneficial technical effects brought about by this invention include:

[0027] 1. The air-material channel and air-flow channel of the drill rod of the powder jet grouting drilling rig are independent. They are connected to the inside of the drilling bit in parallel or in a set. The high-pressure gas ejected from the air-material channel has a guiding effect on the medium in the air-material channel, which can effectively reduce pipeline blockage.

[0028] 2. The concave focusing mechanism installed inside the tunneling drill bit allows the high-pressure airflow ejected from the airflow channel and the gas-solid two-phase flow ejected from the gas-material channel to be reflected after impacting the focusing concave surface on the focusing element. The two reflected high-pressure fluids are then focused and mixed through the focal point, causing the powder curing agent to undergo secondary gasification, which greatly improves the uniformity of the gas-material mixture. In addition, the focusing element is made of hard alloy or ceramic material, which can ensure the structural strength and service life of the focusing element.

[0029] 3. The dual-nozzle design with different lengths of the multi-layer shear mixing drill bit increases the spray radius of the jet grouting pile. That is, by setting nozzles at the near end and far end of the drilling bit, the problem of insufficient spray radius of the near end nozzle can be effectively solved, thereby further increasing the pile diameter of the jet grouting pile.

[0030] 4. The application of multi-layer shear mixing drill bits can significantly improve the pile quality of powder jet grouting piles, including pile uniformity and pile strength continuity. This structural design helps to improve the safety and stability of the project.

[0031] 5. The control module is crucial in the construction of jet grouting pile drilling equipment. It can monitor construction parameters in real time and automatically control the opening and closing of various monitoring instruments, valves and switches of the equipment. This intelligent control method reduces human error, ensures the safety, effectiveness and efficiency of the entire construction process, and improves the controllability and reliability of jet grouting pile construction.

[0032] 6. The multi-channel jet grouting pile drilling rig is equipped with a powerful drive unit that can provide the drilling rig with a large torque of 5tm to 30tm. Therefore, it can construct large-diameter (1500mm) and deep (35m) jet grouting piles, opening up new markets for the engineering application of jet grouting piles and providing higher competitiveness. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of a multi-channel powder jet mixing pile drilling rig according to the present invention.

[0034] Figure 2 This is a schematic diagram of the main structure of the drilling rig of the present invention.

[0035] Figure 3 This is a schematic diagram of the drive device structure of the present invention.

[0036] Figure 4 This is a schematic diagram of the rotary joint structure of Embodiment 1 of the present invention.

[0037] Figure 5 This is a schematic diagram of the rotary joint structure of Embodiment 2 of the present invention.

[0038] Figure 6 This is a schematic diagram of the third type of rotary joint structure of the present invention.

[0039] Figure 7 This is a cross-sectional view of the drill pipe structure in Embodiment 1 of the present invention.

[0040] Figure 8 This is a cross-sectional view of the drill pipe structure in Embodiment 2 of the present invention.

[0041] Figure 9 This is a cross-sectional view of the drill pipe structure in Embodiment 1 of the present invention.

[0042] Figure 10 This is a cross-sectional view of the drill pipe structure in Embodiment 2 of the present invention.

[0043] Figure 11 This is a cross-sectional view of the third type of drill pipe structure of the present invention.

[0044] Figure 12 This is a schematic diagram of the multi-layer shear stirring drill bit structure of Embodiment 1 of the present invention.

[0045] Figure 13 This is a schematic diagram of the multi-layer shear stirring drill bit structure of Embodiment 2 of the present invention.

[0046] Figure 14 This is a schematic diagram of the structure of area A of the multi-layer shear stirring drill bit in Embodiment 1 of the present invention.

[0047] Figure 15 This is a schematic diagram of the structure of the multi-layer shear stirring drill bit in embodiment 2 of the present invention, specifically section B.

[0048] The labels in the attached diagram are as follows:

[0049] 100. Drill rig body; 110. Tower mast; 120. Cable tie rod; 130. Equipment platform; 140. Drill rod; 141. Outer mixing rod; 142. Inner mixing rod; 143. Gas-material channel; 144. Airflow channel; 147. Pin shaft; 148. Support frame; 150. Drive unit; 151. Power mechanism; 152. Goose head; 153. Rotary joint; 155. Feed inlet; 156. Air inlet; 160. Multi-layer shear mixing drill bit; 161. Outer mixing frame; 162. First mixing blade; 163. Second mixing blade; 164. 165. Drill bit; 166. Far-end nozzle; 167. Near-end nozzle; 168. Focusing chamber; 169. Focusing element; 170. Focusing concave surface; 171. Drainage connector; 172. First drainage channel; 173. Second drainage channel; 180. Traveling unit; 200. Material feeding backstage; 210. High-pressure material tank; 221. Air compressor A; 222. Air compressor B; 231. Vertical pressurization pipeline; 232. Air-material pipeline; 233. Air circuit pipeline; 240. Jetting machine system; 250. Air storage tank; 260. Refrigerated dryer; 300. Control module. Detailed Implementation

[0050] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that various forms of implementation can be formed based on these embodiments. Furthermore, these embodiments are merely for the purpose of illustrative purposes, enabling those skilled in the art to better understand the invention. In use, various features of the present invention can be combined and added to or subtracted from each other.

[0051] like Figures 1 to 13 As shown, a multi-channel powder jet grouting pile drilling rig includes a drilling rig body 100, a material feeding backstage 200, and a control module 300. The drilling rig body 100 includes a tower mast 110, a cable support 120, an equipment platform 130, a drill rod 140, a drive unit 150, a multi-layer shearing mixing drill bit 160, and a traveling unit 180. The drill rod 140 has a material air channel 143 and a gas flow channel 144. The multi-layer shearing mixing drill bit 160 is connected to the bottom of the drill rod 140, and a focusing area is provided at the bottom of the multi-layer shearing mixing drill bit 160. The focusing area is connected to the discharge end of the material air channel 143 and the air outlet of the gas flow channel 144. The bottom of the multi-layer shearing mixing drill bit 160 also has a discharge nozzle connected to the focusing area. The material feeding backstage 200 is electrically connected to the control module 300, and the control module 300 controls the material feeding backstage 200. The material supply control involves continuously and evenly supplying curing agent powder to the drilling rig body 100 through the gas pipeline 232 in the material supply backend 200, and continuously supplying high-pressure gas to the drilling rig body 100 through the gas pipeline 233 in the material supply backend 200. This allows the curing agent powder and high-pressure gas to be transported to the focusing area at the bottom of the multi-layer shear mixing drill bit 160 through the gas channel 143 and the air flow channel 144 in the drill rod 140, respectively. In the focusing area, the gas is reflected, mixed, and vaporized, and then ejected from the discharge nozzle of the multi-layer shear mixing drill bit 160.

[0052] like Figure 1 As shown, the material supply backstage 200 includes a high-pressure material tank 210, an injection system 240, air compressor A221, air compressor B222, an air storage tank 250, and a refrigerated dryer 260. The entire material supply backstage 200 is supplied with high-pressure gas for conveying the curing agent powder by air compressor A221. Air compressor A221 is sequentially connected to the air storage tank 250, the refrigerated dryer 260, the high-pressure material tank 210, the injection system 240, the air-material pipeline 232, and the vertical booster pipeline 231. Air compressor B222 is connected to an air pipeline 233 and provides high-pressure gas for the secondary vaporization of the curing agent powder within the focusing chamber 167 of the multi-layer shear-mixing drill bit 160. The high-pressure material tank 210 is equipped with a screw conveyor to transport the curing agent powder inside the tank to the spraying machine system 240 at a constant rate and quantity. The gas-solid fluid transport channel 232 is provided by the vertical pressurization pipe 231, which provides additional high-pressure gas propulsion through an inclined booster in the vertical ascending section of the gas-solid fluid pipeline 232 to prevent the powder from accumulating and clogging due to gravity. The control module 300 uses a PLC control program to monitor and control the internal pressure of the high-pressure material tank 210, control the design speed and design feed rate of the screw conveyor, and simultaneously control the various switch valves, pressure gauges, regulating valves, and flow meters of the feeding backend 200 to continuously, stably, and uniformly deliver the curing agent powder to the drilling rig body 100 through the gas-solid fluid pipeline 232.

[0053] like Figure 2 As shown, the tower mast 110 is vertically mounted on the equipment platform 130. The inclined support 120 connects the tower mast 110 to the equipment platform 130. The drive unit 150 is suspended from the goose head 152 and pulleys at the top of the tower mast 110, and the pulley group on the goose head 152 drives the drill rod 140 to descend and rise. The traveling unit 180 is located at the bottom of the equipment platform 130. The drive unit 150 includes a power mechanism 151 and a rotary joint 153. The power mechanism 151 is connected to the top of the drill rod 140 through the rotary joint 153, and the power mechanism 151 provides rotational power for the outer stirring rod 141 and the inner stirring rod 142. The rotary joint 153 is provided with a feed inlet 155 and an air inlet 156. The feed inlet 155 is connected to the air-material channel 143 on the drill rod 140, and the air inlet 156 is connected to the airflow channel 144 on the drill rod 140. The main structure of the drilling rig consists of the tower mast 110, the inclined support 120, the equipment platform 130, and the traveling unit 180. The height of the main body 100 of the drilling rig ranges from 22m to 40m, and can be reasonably selected according to the length of the construction pile. The traveling unit 180 can be equipped with a roller type, walking type, or crawler type chassis structure depending on the construction site conditions. The gooseneck 152 and pulley block at the top of the tower mast 110 suspend the drilling tools consisting of the drive unit 150 and the multi-layer shear mixing drill bit 160.

[0054] like Figure 3 As shown, the drive device 150 includes a power mechanism 151 that provides power to the drill rod 140 and a rotary joint 153 for connecting to the drill rod 140. The power mechanism 151 can use two electric motors or two hydraulic motors to drive the outer mixing rod 141 and the inner mixing rod 142 respectively, or it can use a single electric motor or four hydraulic motors to drive the inner and outer mixing rods through a transmission mechanism. The total power of the power mechanism 151 is 90kW to 250kW, and the appropriate power device is selected according to the design construction diameter and pile length. The pile length of the powder jet grouting pile construction is between 10m and 35m, and the construction diameter is between 500mm and 1500mm.

[0055] like Figure 7 and Figure 8 As shown, the drill rod 140 includes an outer stirring rod 141 and an inner stirring rod 142; the drill rod 140 can be assembled in sections, with each short section 140A fixedly connected to form a long drill rod via a male-female hexagonal joint and a pin 147. The inner stirring rod 142 is rotatably connected inside the outer stirring rod 141, and both the outer stirring rod 141 and the inner stirring rod 142 have circular cross-sections. The gas-material channel 143 and the airflow channel 144 have three distribution patterns, such as... Figure 4 , Figure 7 As shown, the gas-material channel 143 and the airflow channel 144 are fixedly arranged side by side inside the inner stirring rod 142. Figure 5 , Figure 8As shown, in the second arrangement of the gas-material channel 143 and the airflow channel 144, the gas-material channel 143 is fixedly installed on the central axis of the inner stirring rod 142. The annular gap between the gas-material channel 143 and the inner stirring rod 142 forms the airflow channel 144, and the gas-material channel 143 is fixed by a three-rib support frame 148. The three-rib support frame 148 serves to fix the inner stirring rod 142 and the gas-material channel 143 together. Figure 6 As shown, in the third arrangement of the gas material channel 143 and the air flow channel 144, the gas material channel 143 is located inside the inner stirring rod 142, and the annular gap between the outer stirring rod 141 and the inner stirring rod 142 forms the air flow channel 144. The inner stirring rod 142 is fixed by a three-rib support frame 148, which serves to fix the outer stirring rod 141 and the inner stirring rod 142.

[0056] like Figures 4 to 6 As shown, the rotary joint 153 has three arrangement structures depending on the air-material channel 143 and air-flow channel 144 of the drill rod 140. When the air-material channel 143 and the air-flow channel 144 are arranged side by side in the inner stirring rod 142, the rotary joint 153 is as follows: Figure 4 As shown, the feed inlet 155 is located at the top center of the rotary joint 153, while the air inlet 156 is located on the side wall of the rotary joint 153. The air-material channel 143 and the airflow channel 144 can be directionally adjusted after entering the inner stirring rod 142, ensuring that the two channels remain on opposite sides of the central axis of the inner stirring rod 142. When the air-material channel 143 is located on the central axis of the inner stirring rod 142, and the annular gap between the air-material channel 143 and the inner stirring rod 142 serves as the airflow channel 144, the rotary joint 153... Figure 5 As shown, the feed inlet 155 and air inlet 156 are located on both sides of the rotary joint 153, and after changing direction, they are connected to the gas-material channel 143 and the airflow channel 144, respectively. When the gas-material channel 143 is located inside the inner stirring rod 142, and the annular gap area between the outer stirring rod 141 and the inner stirring rod 142 serves as the airflow channel 144, the rotary joint 153... Figure 6 As shown, the feed inlet 155 and the air inlet 156 are located on both sides of the rotary joint 153, and after changing direction, they are connected to the air-material channel 143 and the airflow channel 144 respectively.

[0057] like Figure 1 As shown, in the above three structures, the curing agent powder is transported in a gas-solid two-phase flow through the path composed of the gas material pipe 232, the inlet 155 and the gas material channel 143, while the high-pressure gas is transported in a high-pressure airflow through the path composed of the gas pipe 233, the inlet 156 and the airflow channel 144.

[0058] like Figure 12 and Figure 13As shown, the multi-layer shear mixing drill bit 160 is equipped with an outer mixing frame 161, a first mixing wing 162, a second mixing wing 163, and a tunneling drill bit 164. For large-diameter powder jet grouting piles, the diameter of the multi-layer shear mixing drill bit 160 can reach 1500mm. The upper end of the outer mixing frame 161 is fixedly connected to the outer mixing rod 141, and the lower end is rotatably connected to the inner mixing rod 142 through a sliding sleeve. The outer mixing rod 141 drives the outer mixing frame 161 to rotate. The first mixing wing 162 is located inside the outer mixing frame 161 and rotates with the outer mixing frame 161. The second mixing wing 163 is fixedly connected to the inner mixing rod 142 inside the outer mixing frame 161. The inner mixing rod 142 drives the second mixing wing 163 to rotate. The first mixing wing 162 and the second mixing wing 163 are staggered and do not interfere with each other. The use of the multi-layer shear mixing drill bit 160 can realize relative rotational shear mixing between adjacent mixing blades, which can play a more effective role in mixing the foundation soil and further improve the construction efficiency and quality of powder jet mixing piles.

[0059] like Figure 14 and Figure 15 As shown, the tunneling drill bit 164 is installed at the bottom of the multi-layer shear mixing drill bit 160. The focusing area is located inside the tunneling drill bit 164, and the discharge nozzle is located on the outer peripheral wall of the tunneling drill bit 164. A focusing cavity 167 is provided inside the tunneling drill bit 164, which is connected to the bottom of the gas-material channel 143 and the airflow channel 144. A distal nozzle 165 and a proximal nozzle 166, connected to the focusing cavity 167, are respectively provided on both sides of the tunneling drill bit 164, and the two nozzles are horizontally aligned. Both nozzles adopt a converging structure. The combined use of the proximal nozzle 166 and the distal nozzle 165 can meet the needs of constructing large-diameter powder jet grouting piles; that is, areas that cannot be reached by the proximal nozzle 166 can be covered by the curing agent powder sprayed from the distal nozzle 165. A focusing element 168 is provided at the bottom of the focusing chamber 167; the top surface of the focusing element 168 is provided with an upward-opening focusing concave surface 169, and the focusing concave surface 169 forms a focusing area between the material outlet end of the gas-material channel 143 and the air outlet end of the airflow channel 144. The focusing point of the focusing concave surface 169 is located below the horizontal line connecting the near-end nozzle 166 and the far-end nozzle 165.

[0060] The drill bit connected to the multi-layer shear mixing drill bit 160 adopts a dual-channel design, which can independently and simultaneously deliver high-pressure airflow and gas-solid two-phase flow, effectively reducing pipeline blockage. Furthermore, through the concave focusing structure inside the drill bit, the high-pressure airflow ejected from the airflow channel 144 and the gas-solid two-phase flow ejected from the gas material channel 143 are reflected after impacting the concave focusing element 168. The two reflected fluids are focused and mixed through the focal point, causing the curing agent powder to undergo secondary gasification, thereby improving the uniformity of the mixture. This further helps to improve the uniformity of powder jet grouting pile mixing and the continuity of pile strength. At the same time, it improves the pile formation quality and efficiency of powder jet grouting mixing piles.

[0061] The drilling bit 164 and the inner stirring rod 142 of the drill bit are equipped with a flow guide 170 at their bottoms. The flow guide 170 is located inside the focusing chamber 167. The flow guide 170 is provided with a first flow guide 171 that communicates with the gas-material channel 143 and a second flow guide 172 that communicates with the airflow channel 144. The lower ends of both the first flow guide 171 and the second flow guide 172 are flared. The dual-pipe flow guide structure design of the flow guide 170 can effectively reduce pipeline blockage. At the same time, the flared structure design provides auxiliary power for the gas-solid two-phase flow ejected from the gas-material channel 143, which not only reduces the risk of nozzle blockage but also increases the nozzle's spray radius.

[0062] A construction method for a multi-channel powder jet grouting pile drilling rig includes the following construction steps:

[0063] S1. Before construction, align the multi-layer shear mixing drill bit 160 of the drilling rig body 100 with the construction pile position, and adjust the verticality of the tower mast 110 and drill rod 140; inject the curing agent powder required for construction into the high-pressure material tank 210, and close the inlet and outlet of the high-pressure tank.

[0064] S2. Turn on air compressor A221 to maintain unobstructed air supply to air material pipeline 232, air material channel 143 and vertical booster pipeline 231 according to the planned air supply pressure and air supply volume. At the same time, turn on air compressor B222 to supply air to air pipeline 233 and air flow channel 144 to provide sufficient high-pressure gas for the curing agent powder to achieve secondary gasification inside focusing chamber 167.

[0065] S3. During the rotary drilling and mixing stage, the drive device 150 drives the inner and outer mixing rods to rotate downwards in opposite directions. The first mixing blade 162 and the second mixing blade 163 of the multi-layer shear mixing drill bit 160 rotate and mix the foundation soil at a set speed. At the same time, the spiral conveyor is turned on to stably and quantitatively deliver curing agent powder to the jetting system 240. The gas-solid two-phase fluid is injected into the foundation soil through the gas-material pipeline 232, the gas-material channel 143, and the far-end nozzle 165 and the near-end nozzle 166 via high-pressure gas jetting. The downward construction continues until the designed pile bottom elevation is reached and the material supply is stopped.

[0066] S4. During the drilling tool rotation and lifting mixing stage, the inner and outer mixing rods rotate in opposite directions and the drill rod 140 is lifted at a set speed. During this construction, a small amount of high-pressure gas is continuously injected through each nozzle to ensure that each nozzle is not blocked, until the multi-layer shear mixing drill bit 160 is lifted off the ground, the gas supply is stopped and the powder jet pile construction is completed.

[0067] S5. Move the machine to the next pile location and repeat the process steps from S1 to S4 to construct the next jet grouting pile.

[0068] Example 1

[0069] The following is combined with, for example Figures 1-4 Sections 7, 9, 12, and 14 further elaborate on the present invention. The engineering background of this embodiment is a foundation pit support project for an intercity train station in a riverside city. Powder jet grouting piles are used to reinforce both sides of the continuous wall surrounding the foundation pit. The piles are 30m long and 1200mm in diameter. Basic geological conditions: Within 30 meters below the surface, there are three soil layers: ① miscellaneous fill, 1-2m thick; ② silty soil, 20-25m thick, 78% water content, void ratio 1.42, SPT blow count 1-2; ③ silty clay, 10-15m thick, 57% water content, void ratio 0.88, SPT blow count 9-12. The powder jet grouting piles use PO 42.5 cement with a cement content of 20%. A dual-channel powder jet grouting pile drilling rig is used for construction. The construction process employs a four-stirring, two-jetting drilling and powder jetting technique. The requirement is that the unconfined compressive strength of the core samples taken from the grouting piles after 28 days should not be less than 1.2MPa.

[0070] In this embodiment, the drilling rig body 100 is 36m high, the construction site has been hardened, the walking unit 180 uses a tracked chassis, and the power mechanism 151 in the drive device 150 uses dual motors with a motor power of 2. ╳ 75kW, driving the outer stirring rod 141 and the inner stirring rod 142 respectively; the rotary joint 153 adopts Figure 4 Medium structure, drill pipe 140 adopts Figure 6 , Figure 8 In the intermediate structure, the gas-material channel 143 and the airflow channel 144 are arranged side by side in the inner stirring rod 142; the multi-layer shear stirring drill bit 160 adopts... Figure 10 In the middle structure, since the gas supply channel 143 and the air flow channel 144 are arranged side by side, the structure of the tunneling drill bit 164 is as follows: Figure 12 As shown, the first drainage channel 171 and the second drainage channel 172 on the drainage connector 170 are arranged side by side. The gas-material channel 143 is connected to the first drainage channel 171, and the airflow channel 144 is connected to the second drainage channel 172. The lower ends of the first drainage channel 171 and the second drainage channel 172 are both flared structures. The focusing chamber 167 is connected to the bottom of the gas-material channel 143 and the airflow channel 144. The left and right sides of the tunneling drill bit 164 are respectively provided with a distal nozzle 165 and a proximal nozzle 166 connected to the focusing chamber 167. The two nozzles are horizontally aligned and have a constricted structure. The bottom of the focusing chamber 167 is provided with a focusing element 168, and its top surface is provided with an upward-opening focusing concave surface 169. The focusing point of the focusing concave surface 169 is located below the horizontal line of the distal nozzle 165 and the proximal nozzle 166.

[0071] The construction process in this embodiment is the same as the specific implementation method described above, and will not be repeated here.

[0072] Example 2

[0073] The following is combined with, for example Figures 1-3 5, 8, 10, 13 and 15 further illustrate the present invention. The engineering background of this embodiment is the foundation engineering of a high-rise office building in a port. The core composite pile is used as the foundation, wherein the powder jet mixing pile is 22m long and 1000mm in diameter, and PHC pipe piles are inserted inside, with a diameter of 800mm and a length of 30m. The design ultimate bearing capacity of a single pile is 2500kN.

[0074] The basic geological conditions of this embodiment are as follows: ① Silt layer, thickness 11-12m, water content 82%, void ratio 1.456, SPT blow count 1-2; ② Saturated soft clay, thickness 12-18m, water content 64%, void ratio 1.875, SPT blow count 7-10; ③ Silty clay, thickness 10-14m, water content 56%, void ratio 0.732, SPT blow count 12-18. KD curing agent is used as the reinforcing material for the powder jet grouting piles, with a dosage of 15%. A dual-channel powder jet grouting pile drilling rig is used for construction, employing a two-mixing-one-jetting drilling and powder jetting construction process. Precast pipe piles are implanted using a pile clamping machine.

[0075] The dual-channel powder jet grouting and mixing pile drilling rig in this embodiment has a similar structure to that in Embodiment 1, except that: the main body 100 of the mixing pile drilling rig in Embodiment 2 is 30m high, the walking unit 180 adopts a walking chassis, and the power mechanism 151 in the drive device 150 uses two hydraulic motors with a power of 2... ╳ 55kW, driving the outer stirring rod 141 and the inner stirring rod 142 respectively; the rotary joint 153 adopts Figure 5 Medium structure, drill pipe 140 adopts Figure 7 and Figure 9 The structure includes an air-material channel 143 located on the central axis of the inner stirring rod 142. The annular gap between the air-material channel 143 and the inner stirring rod 142 forms an airflow channel 144, and the air-material channel 143 is fixed by a three-rib support frame 148.

[0076] Multi-layer shear stirring drill bit 160 adopts Figure 11 The structure of the tunneling drill bit 164 is such that, since the airflow channel 144 is wrapped around the air material channel 143, the structure of the tunneling drill bit 164 is as follows: Figure 13As shown. The second drainage channel 172 on the drainage connector 170 wraps around the outside of the first drainage channel 171. The gas channel 143 is connected to the first drainage channel 171, and the airflow channel 144 is connected to the second drainage channel 172. The lower ends of both the first drainage channel 171 and the second drainage channel 172 are flared structures. The focusing chamber 167 is connected to the bottom of the gas channel 143 and the airflow channel 144. The left and right sides of the tunneling drill bit 164 are respectively provided with a distal nozzle 165 and a proximal nozzle 166 connected to the focusing chamber 167. The two nozzles are horizontally aligned and both are constricted structures. The bottom of the focusing chamber 167 is provided with a focusing element 168, and its top surface is provided with an upward-opening focusing concave surface 169. The focusing point of the focusing concave surface 169 is located below the horizontal line of the distal nozzle 165 and the proximal nozzle 166.

[0077] The construction method in this embodiment is the same as that in the specific implementation method, and will not be described again.

[0078] In summary, the beneficial technical effects brought about by this invention include:

[0079] 1. The drill rod air material channel 143 and air flow channel 144 of the powder jet pile drilling rig are independent of each other. They are connected to the inside of the tunneling drill bit 164 in parallel or in a sleeve. The high-pressure gas ejected from the diversion channel has a diversion effect on the medium in the air material channel 143, which can effectively reduce pipeline blockage.

[0080] 2. The concave focusing mechanism installed in the tunneling drill bit 164 can cause the high-pressure airflow ejected from the airflow channel 144 and the gas-solid two-phase flow ejected from the gas-material channel 143 to be reflected after impacting the focusing concave surface 169 on the focusing element 168. The two reflected high-pressure fluids are focused and mixed through the focal point, causing the powder curing agent to undergo secondary gasification, which greatly improves the uniformity of the gas-material mixture. In addition, the focusing element 168 is made of hard alloy or ceramic material, which can ensure the structural strength and service life of the focusing element 168.

[0081] 3. The design of the multi-layer shear mixing drill bit 160 with dual nozzles of different lengths increases the spray radius of the jet grouting pile. That is, by setting nozzles at the near end and far end of the drilling drill bit 164, the problem of insufficient spray radius of the near end nozzle 166 can be effectively solved, thereby further increasing the pile diameter of the jet grouting pile.

[0082] 4. The application of the multi-layer shear mixing drill bit 160 can significantly improve the pile quality of powder jet grouting piles, including pile uniformity and pile strength continuity; this structural design helps to improve the safety and stability of the project.

[0083] 5. The control module 300 is crucial in the construction of jet grouting pile drilling equipment. It can monitor construction parameters in real time and automatically control the opening and closing of various monitoring instruments, valves and switches of the equipment. This intelligent control method reduces human error, ensures the safety, effectiveness and efficiency of the entire construction process, and improves the controllability and reliability of jet grouting pile construction.

[0084] 6. The multi-channel jet grouting pile drilling rig is equipped with a powerful drive unit 150, which can provide the drilling rig with a large torque of 5tm to 30tm. Therefore, it can construct large-diameter (1500mm) and deep (35m) jet grouting piles, opening up new markets for the engineering application of jet grouting piles and providing higher market competitiveness.

[0085] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A multi-channel powder jet grouting pile drilling rig, characterized in that, The system includes a drilling rig body (100), a material supply backend (200), and a control module (300). The drilling rig body (100) includes a drill rod (140) and a multi-layer shear mixing drill bit (160). The drill rod (140) has at least a gas-material channel (143) and an airflow channel (144). The multi-layer shear mixing drill bit (160) is connected to the bottom of the drill rod (140), and a focusing area is provided at the bottom of the multi-layer shear mixing drill bit (160). The focusing area is connected to the discharge end of the gas-material channel (143) and the discharge end of the airflow channel (144). The bottom of the multi-layer shear mixing drill bit (160) is also provided with a discharge nozzle connected to the focusing area. The material supply backend (200) and the control module (300) are connected to the control module. The block (300) is connected, and the control module (300) controls the feeding and spraying of the feeding backstage (200). The curing agent powder is continuously and uniformly supplied to the drilling rig body (100) through the gas pipeline (232) in the feeding backstage (200), and high-pressure gas is continuously supplied to the drilling rig body (100) through the gas pipeline (233) in the feeding backstage (200). The curing agent powder and high-pressure gas are respectively transported through the gas channel (143) and the air flow channel (144) in the drill rod (140) to the focusing area at the bottom of the multi-layer shear mixing drill bit (160). In the focusing area, the mixture is mixed and gasified by focusing reflection to form a uniform mixture, which is then sprayed out from the discharge nozzle of the multi-layer shear mixing drill bit (160). The drill rod (140) includes an outer stirring rod (141) and an inner stirring rod (142); the inner stirring rod (142) is rotatably connected inside the outer stirring rod (141); The multi-layer shear mixing drill bit (160) includes a mixing frame (161), a first mixing blade (162), a second mixing blade (163), and a tunneling drill bit (164). The upper end of the mixing frame (161) is fixedly connected to the outer mixing rod (141), and the lower end of the mixing frame (161) is rotatably connected to the inner mixing rod (142) through a sliding sleeve. The first mixing blade (162) is fixedly connected in layers inside the mixing frame (161); the second mixing blade (163) is fixedly connected in layers inside the mixing frame (161). On the inner stirring rod (142) of the part, the first stirring blade (162) and the second stirring blade (163) are arranged at a staggered interval and do not interfere with each other; the outer stirring rod (141) drives the stirring frame (161) and the first stirring blade (162) to rotate, and the inner stirring rod (142) drives the second stirring blade (163) to rotate; the tunneling drill bit (164) is fixedly connected to the bottom of the inner stirring rod (142), the focusing area is set inside the tunneling drill bit (164), and the discharge nozzle is set on the outer peripheral wall of the tunneling drill bit (164); A flow guide (170) is provided between the bottom of the tunneling drill bit (164) and the inner stirring rod (142). The flow guide (170) is provided with a first flow guide (171) communicating with the gas material channel (143) and a second flow guide (172) communicating with the air flow channel (144). The lower ends of the first flow guide (171) and the lower ends of the second flow guide (172) are both flared structures. The multi-layer shear stirring drill bit (160) has a focusing cavity (167) at its bottom; a focusing element (168) is provided at the bottom of the focusing cavity (167); the top surface of the focusing element (168) has a focusing concave surface (169) with an upward opening, and the focusing concave surface (169) forms the focusing area between the material outlet end of the gas channel (143) and the air outlet end of the air flow channel (144); The discharge nozzle includes a distal nozzle (165) and a proximal nozzle (166). The distal nozzle (165) is disposed on one side wall of the tunneling drill bit (164) through a nozzle guide. The proximal nozzle (166) is disposed on the side wall of the tunneling drill bit (164) opposite to the distal nozzle (165). The distal nozzle (165) and the proximal nozzle (166) are horizontally aligned. The focal point of the focusing concave surface (169) is located below the horizontal line of the distal nozzle (165) and the proximal nozzle (166).

2. The multi-channel powder jet grouting and mixing pile drilling rig equipment according to claim 1, characterized in that, The gas material channel (143) and the air flow channel (144) are fixedly arranged side by side inside the inner stirring rod (142).

3. The multi-channel powder jet grouting pile drilling rig equipment according to claim 1, characterized in that, The gas material channel (143) is fixedly installed on the central axis of the inner stirring rod (142). The annular gap between the gas material channel (143) and the inner stirring rod (142) forms the airflow channel (144), and the gas material channel (143) is fixed by a three-rib support frame (148).

4. The multi-channel powder jet grouting pile drilling rig equipment according to claim 1, characterized in that, The gas channel (143) is located inside the inner stirring rod (142), and the annular gap between the outer stirring rod (141) and the inner stirring rod (142) forms the airflow channel (144).

5. The multi-channel powder jet grouting pile drilling rig equipment according to claim 1, characterized in that, The drilling rig body (100) also includes a tower mast (110), a tie rod (120), an equipment platform (130), a drive unit (150), and a traveling unit (180). The tower mast (110) is vertically mounted on the equipment platform (130). The tie rod (120) fixes the tower mast (110) to the equipment platform (130). The drive unit (150) is suspended above the tower mast (110) and uses a pulley system on the gooseneck (152) at the top of the tower mast (110) to drive the drill rod (140) to descend and rise. The traveling unit (180)... Unit (180) is located at the bottom of the equipment platform (130). The drive device (150) includes a power mechanism (151) and a rotary joint (153). The power mechanism (151) is connected to the top of the drill rod (140) through the rotary joint (153), and the power mechanism (151) provides rotational torque to the drill rod (140). The rotary joint (153) is provided with a feed inlet (155) and an air inlet (156). The feed inlet (155) is connected to the air-material channel (143) on the drill rod (140), and the air inlet (156) is connected to the air-material channel (143) on the drill rod (140). The airflow channel (144) is connected; the material supply back-end (200) includes a high-pressure material tank (210), air compressor A (221), air compressor B (222), a jetting system (240), a gas storage tank (250), and a refrigerated dryer (260); the high-pressure material tank (210) uses a high-pressure tank body to hold curing agent powder, and the curing agent powder is stably and evenly transported to the jetting system (240) at the bottom of the tank body according to the set parameters by a screw conveyor device, and the high-pressure gas generated by air compressor A (221) is fully mixed with the curing agent powder in the jetting system (240) to form a gas-solid two-phase flow, and then the gas-material pipeline (232) is used for conveying; the gas pipeline (232) is connected to the feed port (155) on the drilling rig body (100) to supply curing agent powder, and at the same time, a vertical booster pipeline (231) supplied by the branch of air compressor A (221) is added to the vertical rising part of the gas pipeline (232); the feeding backstage (200) is further equipped with air compressor B (222) which is connected to the air inlet (156) on the drilling rig body (100) through the air pipeline (233) to supply high-pressure gas; the control module (300) is responsible for the monitoring, control and operation of the entire feeding backstage (200) equipment;The control module (300) uses a PLC control program to monitor and control the pressure inside the high-pressure tank (210), control the designed rotation speed of the screw conveyor and the designed amount of curing agent powder to be dispensed, and effectively monitor and control the various switching valves, pressure gauges, regulating valves, and flow meters in the material supply backend (200). This ensures that the curing agent powder is continuously, stably, quantitatively, and uniformly injected into the foundation soil through the gas pipeline (232), gas channel (143), and gas nozzle.

6. A construction method for a multi-channel powder jet grouting pile drilling rig, characterized in that, The application of the multi-channel powder jet grouting pile drilling rig equipment according to any one of claims 1-5 includes the following steps: 1) Before construction begins, the drilling rig body (100) accurately aligns the multi-layer shear mixing drill bit (160) with the pile position to be constructed using the positioning system, and uses the electronic leveling instrument to adjust each hydraulic outrigger to keep the verticality of the tower mast (110) and drill rod (140) within 1.5%; inject the required curing agent powder into the high-pressure material tank (210) and close each feed and exhaust switch on the high-pressure tank body; 2) Turn on air compressor A (221) to supply air, and ensure that the air supply pipeline (232), air supply channel (143) and vertical booster pipeline (231) are unobstructed according to the planned air supply pressure and air supply volume. At the same time, turn on air compressor B (222) to supply air to the air supply pipeline (233) and air flow channel (144) to provide high pressure gas for the curing agent powder to undergo secondary gasification inside the focusing chamber (167); 3) During the drilling and jet mixing stage of the drilling tool, the gooseneck (152) controls the drilling tool to descend at a set drilling speed through pulleys and winches. The drive device (150) drives the outer mixing rod (141) and the inner mixing rod (142) to rotate in opposite directions, so that the first mixing blade (162) and the second mixing blade (163) of the multi-layer shear mixing drill bit (160) rotate and mix the foundation soil relative to each other at a set rotation speed. After the multi-layer shear mixing drill bit (160) enters the soil, the screw conveyor in the high-pressure material tank (210) is immediately turned on to stably and quantitatively feed the material into the jetting machine system (240). The curing agent powder is fed into the focusing chamber (167) of the tunneling drill bit (164) through the gas pipeline (232) and gas channel (143) under the impingement of high pressure gas. It also enters the focusing chamber (167) of the tunneling drill bit (164) through the gas pipeline (233) and air flow channel (144), providing good conditions for the curing agent powder to undergo secondary gasification inside the focusing chamber (167). After secondary mixing and gasification, the uniformly mixed curing agent powder is sprayed and mixed into the foundation soil through the far end nozzle (165) and near end nozzle (166). The material supply is stopped when the design pile bottom elevation is reached. 4) During the upward rotation and mixing stage of the drill bit, the outer mixing rod (141) and the inner mixing rod (142) rotate in opposite directions to lift the drill rod (140) upward at the set lifting speed. During this process, a small amount of high-pressure gas is continuously sprayed through the nozzle to ensure that the nozzle is not blocked by the soil until the multi-layer shear mixing drill bit (160) is lifted out of the ground and the gas supply is stopped. At this time, the construction of the powder jet mixing pile ends. 5) Move the machine to the next new pile location and repeat the above process steps to construct the next powder jet grouting pile.

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