Soft soil base powder jet mixing pile construction device and construction method

Abstract

This application provides a construction device and method for powder-jet mixing piles in soft soil, aiming to solve the problems of uneven distribution of cement dry powder in the pile body and difficulty in controlling the amount of cement dry powder in existing powder-jet mixing pile technology, as well as the problem of easy clogging in powder-jet mixing piles. It provides a device and method for precise control of cement dry powder. The core of this application is that the cement dry powder is controlled by a pulse unit and a control module, which cyclically controls the opening and closing sequence of the discharge valve, control valve, and air inlet valve of the pulse unit within a preset spraying cycle. When the discharge valve is open, the control valve repeatedly opens and closes at a preset pulse cycle. After the discharge valve is closed, the air inlet valve is opened to pressurize the powder pipeline, thereby forming a periodic pulsed gas-solid flow in the powder pipeline. This achieves quantitative supply of cement dry powder and ensures a smooth supply of cement dry powder.

Description

Technical Field

[0001] This application relates to the field of soft soil foundation treatment technology, specifically to a soft soil foundation powder jet mixing pile construction device and construction method. Background Technology

[0002] Soft soil foundations, also known as soft soil bases, generally refer to weak soil layers with high water content, low bearing capacity, and high compressibility. They are widely distributed in my country, mainly concentrated in coastal areas, inland lake basins, and riverbanks. Due to their low strength and large settling potential, soft soil often causes significant settlement hazards to roads and buildings. Improper handling can greatly affect the construction and use of roads and buildings. In soft soil foundation reinforcement, cement mixing (wet spraying) and powder spraying (dry spraying) are commonly used. Both are deep mixing methods, which forcibly mix cement and other solidifying agents with the soft soil to form cement-soil piles, improving the integrity, water stability, and strength of the foundation.

[0003] The powder jet mixing method is a foundation treatment technology that strengthens soft soil by spraying powder reinforcement materials into the soft soil foundation and forcibly mixing them. This method uses compressed air to transport materials such as quicklime powder and cement. The drill blades of the deep powder jet mixer rotate to make the reinforcement agent and in-situ soft clay evenly mixed. Through physical and chemical reactions, a cement pile composite foundation is formed. Therefore, it is particularly suitable for soft soil with high water content.

[0004] For example, the invention patent with patent number 202410792778.4 discloses an intelligent construction method and construction device for bidirectional mixing powder jetting piles. The pile driver is equipped with various intelligent devices, which enables the pile driver to have intelligent functions, thereby realizing automatic control of the air volume and the amount of powder jetting.

[0005] For example, the invention patent with patent number 202410217795.5 discloses a multi-channel powder jet mixing pile drilling rig equipment and construction method. It uses a gas-solid two-phase mixed compressed fluid and a high-pressure airflow to 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 being reflected, mixed and vaporized inside the focusing area.

[0006] However, in the existing technology, due to the characteristics of powder jet grouting piles, it is difficult to control the weight and uniformity of cement dry powder during the construction of powder jet grouting piles, resulting in the cement dry powder content not meeting the design requirements or not being evenly distributed in the pile body, resulting in poor pile quality; secondly, there is the problem of easy pipe blockage. Because the mixing pile is relatively high, the cement dry powder is transported through high-pressure gas, which can easily accumulate in the pipeline, leading to blockage. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] In view of this, this application provides a construction device and method for powder jet grouting piles in soft soil, to overcome the problems of difficulty in controlling the uniformity of cement dry powder and easy blockage of pipelines in existing powder jet grouting pile construction.

[0009] (II) Technical Solution

[0010] The embodiments in this specification provide the following technical solutions:

[0011] This specification provides an embodiment of a soft soil foundation powder jet grouting and mixing pile construction device, including a feeding mechanism, an air compression mechanism, and a mixing pile machine. The feeding mechanism includes a support frame, a pressure mortar tank, and a control module. The pressure mortar tank is connected to the air compression mechanism via an air supply pipeline. A pulse unit is connected to the lower end of the pressure mortar tank. The pulse unit includes a pulse pipe, and a discharge valve, a control valve, and a spray nozzle are sequentially arranged on the pulse pipe along the cement dry powder conveying direction. The spray nozzle is connected to the mixing pile machine via a powder pipeline, and the control valve is connected to the spray nozzle. The pulse tube between them is provided with an air inlet, and an air inlet valve is provided at the air inlet. The air inlet valve is connected to the air compression mechanism through an air supply pipeline. The control module is configured to cyclically control the opening and closing sequence of the discharge valve, control valve and air inlet valve within a preset injection cycle. Within a preset injection cycle, when the discharge valve is open, the control valve repeatedly opens and closes according to the preset pulse cycle to achieve intermittent powder supply. When the discharge valve is closed, the air inlet valve opens to pressurize the powder pipeline to form a periodic pulsed gas-solid flow in the powder pipeline.

[0012] In some embodiments, a weight sensor is provided on the support, and the pressure ash jar is fixedly connected to the support through the weight sensor; the weight sensor feeds back the collected weight signal to the control module in real time; the control module dynamically adjusts the opening duration of the discharge valve according to the weight information fed back by the weight sensor, so as to realize the quantitative supply of cement dry powder.

[0013] In some embodiments, the mixing pile machine is equipped with a depth sensor, which collects the drilling depth of the mixing pile machine in real time and feeds it back to the control module. The control module calculates the current drilling speed based on the rate of change of depth over time. Based on the real-time drilling speed, the control module dynamically calculates the required amount of dry cement powder in each preset spraying cycle. The control module achieves precise powder supply through any of the following methods:

[0014] Adjust the opening duration of the discharge valve to match the amount of discharged powder with the required amount of dry cement powder;

[0015] Alternatively, based on the weight signal from the pressure ash hopper fed back by the weight sensor, the discharge valve can be closed when the weight reduction of the pressure ash hopper reaches the required amount of dry cement powder.

[0016] In some embodiments, the control module calculates the deviation between the weight reduction value of the current preset spraying cycle and the target amount of dry cement powder based on the weight information fed back by the weight sensor after the discharge valve is closed. Based on this deviation, the control module compensates and adjusts the opening duration of the discharge valve or the weight of dry cement powder in the next cycle.

[0017] In some embodiments, the single preset injection cycle of the pulse unit is 5 to 15 seconds, and the preset pulse cycle of the control valve is 0.2 to 0.8 seconds.

[0018] In some embodiments, when the drilling speed fed back by the depth sensor is zero or close to zero within a certain preset spraying cycle, the control module determines that the mixing pile machine is in a stagnant state; at this time, in the next preset spraying cycle, the control module automatically closes the discharge valve, stops the supply of dry cement powder, and controls the air inlet valve to open to supplement compressed air into the powder pipeline to maintain the positive pressure state in the powder pipeline.

[0019] In some embodiments, a storage mechanism is further included, comprising a storage hopper and a spiral auger. One end of the spiral auger is connected to the storage hopper, and the other end is connected to the pressure ash jar via a flexible sleeve. The spiral auger has a spiral rod inside, and a motor is provided at one end of the spiral auger. The pressure ash jar is provided with a feed valve, and the control module controls the opening and closing of the motor and the feed valve. When cement dry powder needs to be added, the control module opens the feed valve and starts the motor, causing the spiral auger to deliver cement dry powder to the pressure ash jar. When the amount of material added, as indicated by the weight sensor, reaches a preset value, the control module closes the motor and the feed valve.

[0020] In some embodiments, the air compression mechanism is connected to the pressure ash tank via a three-way pipe. The three-way pipe has three ports: the first port is connected to the air compression mechanism and is equipped with a pressurizing valve; the second port is connected to the pressure ash tank; and the third port is equipped with an exhaust valve connected to an exhaust pipe. The control module controls the opening and closing of the pressurizing valve and the exhaust valve. When the pressure ash tank is depressurized, the control module first closes the pressurizing valve and then opens the exhaust valve to depressurize. After the depressurization is completed, the exhaust valve is closed.

[0021] In some embodiments, a reflux valve and an exhaust valve are respectively provided on both sides of the third end of the three-way pipe. The control module controls the opening and closing of the reflux valve and the exhaust valve. The reflux valve is connected to the pulse unit through a pipeline. When the pressure ash tank is depressurized, the control module first closes the pressurizing valve, opens the reflux valve to depressurize the powder pipeline, and finally opens the exhaust valve to empty the pressure ash tank.

[0022] In some embodiments, when the mixing pile machine is performing dry mixing operation in the soil layer, the discharge valve is closed and the powder supply is stopped; the control module controls the air inlet valve to open and close in a pulse manner to intermittently supplement compressed air to the powder pipeline in order to maintain a positive pressure state in the powder pipeline.

[0023] In some embodiments, the pressure ash tank is equipped with a pressure sensor, which collects the pressure information of the pressure ash tank in real time and feeds it back to the control module. The control module determines whether the pressure inside the tank has reached a preset working threshold based on the pressure signal, and starts the powder spraying operation of the pulse unit or the mixing pile machine after the preset working threshold is reached.

[0024] This specification also provides an embodiment of a method for constructing powder jet grouting piles on soft soil foundations, which specifically includes the following steps:

[0025] S1. Before construction, level the work site and install and position the material supply mechanism, air compression mechanism, and mixing pile machine, and complete the system connection through the air pipeline and powder pipeline;

[0026] S2. Add the required dry cement powder to the pressure ash hopper. The control mechanism obtains the weight of the dry cement powder or the total weight of the pressure ash hopper through the weight sensor.

[0027] S3. Start the air compressor mechanism to fill the pressure ash tank with compressed gas until the pressure inside the pressure ash tank reaches the pre-working pressure.

[0028] S4. Start the mixing pile machine to drill into the soil layer and mix it synchronously; according to the design requirements, the control module activates the pulse unit;

[0029] S5. During the continuous mixing and drilling process of the mixing pile machine, the air compression mechanism continuously supplies air to the pressure tank to stabilize the tank pressure. The control module performs the following operations cyclically during the preset spraying cycle:

[0030] S501. Open the discharge valve to allow the cement powder to be discharged under the pressure of the air inside the tank.

[0031] S502, the synchronous control valve repeatedly opens and closes with a preset pulse cycle to achieve intermittent powder supply, forming a pulsed gas-solid flow, which drives the powder to be transported to the mixing pile machine;

[0032] S503. When the weight sensor feedback indicates that the powder weight loss has reached the target value, or when the discharge valve opening time has reached the set duration, close the discharge valve.

[0033] S504. Immediately open the air intake valve to replenish compressed air into the powder pipeline, push the dry cement powder in the powder pipeline and maintain the pressure.

[0034] S505. After the pressure replenishment is completed, proceed to the next preset spraying cycle and repeat the above process until the mixing pile machine drills to the designed depth or completes the mixing operation.

[0035] S6. Move the mixing pile machine to the next pile position and repeat the above S4 to S5 or S2 to S5 process steps to construct the next pile.

[0036] In some embodiments, a depth sensor is installed on the mixing pile machine to collect the drilling depth of the mixing pile machine in real time and feed it back to the control module. The control module calculates the current drilling speed based on the rate of change of depth over time. The control mechanism dynamically calculates the required amount of dry cement powder in each injection cycle based on the real-time drilling speed. The control module achieves precise powder supply through any of the following methods:

[0037] Adjust the opening duration of the discharge valve to match the amount of discharged powder with the required amount of dry cement powder;

[0038] Alternatively, based on the weight signal from the pressure ash hopper fed back by the weight sensor, the discharge valve can be closed when the weight reduction of the pressure ash hopper reaches the required amount of dry cement powder.

[0039] In some embodiments, the control module calculates the deviation between the weight reduction value of the current preset spraying cycle and the target amount of dry cement powder based on the weight information fed back by the weight sensor after the discharge valve is closed. Based on this deviation, the control module compensates and adjusts the opening duration of the discharge valve or the weight of dry cement powder in the next cycle.

[0040] In some embodiments, the single preset injection cycle of the pulse unit is set to 5 to 15 seconds, and the preset pulse cycle of the control valve is set to 0.2 to 0.8 seconds.

[0041] (III) Beneficial Effects

[0042] Compared with existing technologies, the beneficial effects achieved by at least one of the above-mentioned technical solutions adopted in the embodiments of this specification include at least the following: By controlling the pulse unit to circulate within a preset spraying cycle, the supply amount and overall weight of cement dry powder within each preset spraying cycle are ensured; by controlling the intermittent opening and closing of the valve during the preset pulse cycle and the pressurization effect of the air inlet valve, excessive supply of cement dry powder and blockage are avoided, resulting in a pulsed supply of cement dry powder in the powder pipeline, making the cement dry powder supply more uniform and preventing blockage of the powder pipeline. Furthermore, the supply of cement dry powder is further accurately measured by weight and depth sensors, and the supply amount of cement dry powder during the preset spraying cycle can be monitored and adjusted in real time to avoid cumulative deviations and achieve precise supply. After construction is completed, key data of each pile body are saved to facilitate quality traceability and process optimization. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the overall structure in this application;

[0045] Figure 2 This is a schematic diagram of the material supply mechanism structure in this application;

[0046] Figure 3 This is a schematic diagram of the material storage mechanism in this application;

[0047] Figure 4 This is a schematic diagram of the mixing pile machine structure in this application;

[0048] In the diagram: 100, feeding mechanism; 200, air compression mechanism; 300, mixing pile machine; 400, storage mechanism; 110, support frame; 120, pressure ash tank; 130, pulse unit; 140, control module; 210, air compressor; 220, air storage tank; 230, dryer; 310, pile driver platform; 320, tower; 330, power head; 340, drill rod; 350, drill bit; 410, storage hopper; 420, auger; 111, gravity sensor; 121, feed inlet; 122, feed valve; 123, pulse tube; 124, pressurization port. ; 125. Air inlet; 126. Discharge valve; 127. Control valve; 128. Spray nozzle; 129. Air inlet valve; 131. Discharge port; 132. Pressurization valve; 133. Exhaust valve; 134. Exhaust pipe; 135. Return valve; 136. Air distribution box; 137. Pressure gauge; 138. Pressure sensor; 139. T-connector; 321. Depth sensor; 341. Powder channel; 342. Outer drill rod; 343. Inner drill rod; 351. Mixing blade; 352. Spray nozzle; 403. Opening; 404. Motor; 405. Spiral rod; 406. Soft sleeve. Detailed Implementation

[0049] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0050] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0051] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0052] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0053] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0054] Combination Figures 1-4As shown, this application provides a soft soil foundation powder jetting and mixing pile construction device, including a feeding mechanism 100, an air compression mechanism 200, and a mixing pile machine 300; the feeding mechanism 100 includes a support 110, a pressure mortar tank 120, and a control module 140; a weight sensor 111 is provided on the support 110, and the pressure mortar tank 120 is fixedly connected to the support 110 through the weight sensor 111, and the weight information collected by the weight sensor 111 is fed back to the control module 140; the top of the pressure mortar tank 120 is provided with a feed inlet 121 and a pressurization port 124, and a feed valve 122 is provided at the feed inlet 121, through which dry cement powder enters The pressure ash tank 120 has a pressurization port 124 connected to an air compression mechanism 200 via an air supply pipeline. The air compression mechanism 200 pressurizes the pressure ash tank 120 through the air supply pipeline. The bottom of the pressure ash tank 120 is conical, and a discharge port 131 is provided at the bottom of the conical shape. A pulse unit 130 is connected to the lower end of the discharge port 131. The pulse unit 130 includes a pulse tube 123, and a discharge valve 126, a control valve 127, and a spray nozzle 128 arranged sequentially along the powder conveying direction on the pulse tube 123. An air inlet 125 is provided on the pulse tube between the control valve 127 and the spray nozzle 128, and an air inlet valve 129 is provided on the air inlet 125. Air valve 129 is connected to air compression mechanism 200 via air supply pipeline, and spray nozzle 128 is connected to mixing pile machine 300 via powder pipeline. Control module 140 uses PLC control program to control the opening and closing of feed valve 122, discharge valve 126, control valve 127, and air inlet valve 129, specifically as follows: feed valve 122 is configured to open when adding cement dry powder and remain closed when pressurized ash tank 120; discharge valve 126, control valve 127, and air inlet valve 129 are configured to open and cycle according to a preset spraying cycle under the scheduling of control module 140; within a preset spraying cycle, discharge valve 126 is configured to... Based on weight or time cycle, the control valve 127 is configured to open and close repeatedly according to a preset pulse cycle when the discharge valve 126 is open, thereby achieving intermittent powder supply and forming an intermittent pulsed gas-solid flow. The pulsed gas-solid flow forms a periodic impact on the powder pipeline and pushes the cement dry powder to the mixing pile machine 300, avoiding the blockage of the powder pipeline or metering loss caused by excessive instantaneous flow of cement dry powder. The air inlet valve 129 is configured to open when the control valve 127 is closed to supplement the pressure of the powder pipeline and continue to push the gas-solid flow to the mixing pile machine 300, preventing the powder pipeline from losing pressure.

[0055] It should be understood that this application involves two different levels of time control cycles:

[0056] (1) Preset injection cycle: refers to the total time length for the control module 140 to perform one complete powder supply-pressure replenishment operation, that is, the time interval from the opening of the discharge valve 126, through the pulse powder supply of the control valve 127, the closing of the discharge valve 126, and the pressure replenishment of the air inlet valve 129, until the next opening of the discharge valve 126. This cycle is set according to the pile design dosage, drilling speed and soil properties, with a preferred value of 5 to 15 seconds. Within one preset injection cycle, the system completes one quantitative delivery of the target powder amount.

[0057] (2) Preset pulse cycle: refers to the time interval between two consecutive openings of the control valve 127 within a single preset injection cycle while the discharge valve 126 remains open. This cycle is used to divide the continuous powder flow into multiple discrete powder clusters to form a pulsed gas-solid flow, with a preferred value of 0.2 seconds to 0.8 seconds. By adjusting this preset pulse cycle, the distribution density and pushing rhythm of the powder in the pipeline can be controlled, effectively preventing blockage or metering deviation caused by excessive instantaneous flow.

[0058] The two cycles have a clear inclusion relationship: a preset injection cycle contains one or more preset pulse cycles. For example, when the preset injection cycle is 8 seconds and the preset pulse cycle is 0.4 seconds, if the discharge valve 126 is open for 2 seconds based on weight or set duration, the control valve 127 can complete about 3-5 opening and closing cycles during the discharge period, and the air inlet valve 129 can complete one or more pressure replenishments in the remaining 6 seconds, thereby achieving fine powder modulation and stable conveying.

[0059] The air compression mechanism 200 is used to supply compressed air to the pressure ash tank 120 and the air inlet 125. This application does not limit the specific method of supplying compressed air, as long as a stable supply of compressed gas can be achieved; for example, the air compressor 210 can be used to supply air directly, or the air compressor 210 can be used in conjunction with the air storage tank 220 to supply air indirectly. In this embodiment, the air compression mechanism 200 includes an air compressor 210, an air storage tank 220 and a dryer 230 connected in sequence by pipelines. The compressed gas generated by the air compressor 210 is transported to the air storage tank 220 for pressure stabilization and storage, and then dried by the dryer 230 to remove moisture, and finally transported to the pressurization port 124 and the air inlet 125 of the pressure ash tank 120 to meet the requirements of a dry and stable air source supply and to prevent the moisture in the compressed air from combining with the dry cement powder and causing clumping.

[0060] The mixing pile machine 300 is a common foundation treatment construction equipment in this field, mainly used for drilling into the soil layer and simultaneously performing mixing operations. This application does not limit the specific structural form of the mixing pile machine 300, as long as it can achieve the drilling and mixing functions. For example, the main structure of the drilling rig disclosed in Chinese invention patent number "202410217795.5" in the background art can be adopted, or the main structure of the drilling rig with bidirectional mixing from the inventor's earlier invention patent "201410650137.1" "Construction Method of Bidirectional Mixing Pile Equipment" can be adopted. In this embodiment, the mixing pile machine 300 includes a pile machine platform 310, a tower 320, a power head 330, a drill rod 340, and a drill bit 350. The tower 320 is installed on the pile machine platform 310. The power head 330 is movably arranged along the axial direction of the tower 320. The lower end of the power head 330 is connected to the drill rod 340 to drive the drill rod 340 to rotate. The drill rod 340 is provided with a powder channel 341 extending axially. The upper end of the powder channel 341 is connected to the spray nozzle 128 through a powder pipeline. The bottom of the drill rod 340 is fixedly connected to the drill bit 350. The drill bit 350 is provided with at least one set of mixing blades 351 and a spray nozzle 352 communicating with the powder channel 341 to spray cement dry powder carried by compressed air into the formation to achieve synchronous mixing and powder injection operations.

[0061] In some embodiments, the drill rod 340 includes an inner drill rod 343 and an outer drill rod 342 nested together. The bottom ends of the inner drill rod 343 and the outer drill rod 342 are each provided with at least one set of stirring blades 351, together forming a drill bit 350. The inner drill rod 343 is hollow, forming a powder channel 341. An injection port 352 is provided at the bottom of the inner drill rod 343 or near the stirring blades 351. The power head 330 includes a transmission box and a drive motor (not shown in the figure). The transmission box is used to drive the inner drill rod 343 and the outer drill rod 342 to rotate synchronously in opposite directions, thereby achieving bidirectional stirring. The transmission box is a very mature technology in the field of soft soil foundation reinforcement, and will not be described in detail here. Of course, the transmission box can also be the utility model CN201420178903.4 "Single-shaft bidirectional mixing box" and CN201821054059.9 "A bidirectional mixing head transmission box for multiple machine types" applied for earlier by the inventor. The above transmission boxes have mature structures and high reliability, and can effectively meet the driving requirements of bidirectional rotation of dual shafts in this application.

[0062] When the soft soil foundation powder spraying and mixing pile construction device is running, firstly, cement dry powder is added to the pressure ash tank 120 and the weight of the cement dry powder is obtained through the weight sensor 111. Then, the feed valve 122 is closed. Next, the air compression mechanism 200 fills the pressure ash tank 120 with compressed air through the pressure port 124, so that the pressure in the pressure ash tank 120 rises to the set working pressure. According to the construction process requirements, the mixing pile machine 300 and the control module start pulse unit 130 are started synchronously or asynchronously.

[0063] After the control module 140 opens the discharge valve 126, the dry cement powder in the pressure ash tank 120 is discharged from the discharge valve 126 under air pressure. Simultaneously, the control module 140 controls the control valve 127 to open and close intermittently within a preset pulse cycle, intermittently cutting off the dry cement powder ejected from the discharge valve 126, thus forming intermittent pulsed air-solid flow. This pulsed air-solid flow periodically impacts the powder pipeline and propels the dry cement powder towards the mixing pile machine 300, preventing pipeline blockage or metering loss due to excessive instantaneous flow of dry cement powder. When the weight of the dry cement powder in the pressure ash tank 120 decreases to a predetermined threshold or the discharge valve 126... When the opening time of valve 126 reaches the set duration, control module 140 closes the discharge valve 126 and opens the air inlet valve 129 to pressurize the powder pipeline to continue pushing the dry cement powder in the powder pipeline. To further improve the conveying efficiency, the air inlet valve 129 can be opened intermittently to perform one or more short-term pressurization pushes to ensure that the dry cement powder in the powder pipeline is conveyed to the mixing pile machine 300. After the pressurization push is completed, control module 140 closes the air inlet valve 129 and reopens the discharge valve 126 to enter the spraying stage again. The above "spraying-pressurization" process is executed in a cycle until the mixing pile machine 300 reaches the set depth or completes the mixing operation.

[0064] In some embodiments, when the mixing pile machine 300 performs dry mixing operation in the soil layer (i.e., without spraying cement dry powder), the pulse unit 130 stops the powder supply; at this time, the control module 140 controls the air inlet valve 129 to open intermittently to supplement compressed air to the powder pipeline to maintain a positive pressure state in the powder pipeline; this pressure holding operation can effectively prevent powder settling or cement-soil backflow caused by the loss of pressure in the powder pipeline, thereby avoiding blockage of the powder pipeline or drill rod 340, and ensuring that the system can quickly restore stable powder supply in the subsequent spraying stage.

[0065] It should be understood that control valve 127 can close synchronously with discharge valve 126, or control valve 127 can always be in an intermittent opening and closing state during the operation of the injection assembly. When discharge valve 126 is closed, a seal is formed at the upstream end of pulse unit 130. At this time, regardless of the state of control valve 127, it will not affect the subsequent pressure replenishment operation of intake valve 129. However, if discharge valve 126 itself is frequently opened and closed intermittently, it is easy to cause wear or shorten the life of its seals. Therefore, it is preferable to use control valve 127 to open and close synchronously with discharge valve 126.

[0066] It should be understood that the closing of the discharge valve 126 and the opening of the air inlet valve 129 can be performed simultaneously or asynchronously. Specifically, the air inlet valve 129 can be opened at the same time as the discharge valve 126 is closed, or the air inlet valve 129 can be opened after a short delay after the discharge valve 126 is closed. This delay time is usually controlled within 3 seconds to maintain the pressure stability in the powder pipeline and ensure the continuity and pushing effect of the pulsed gas-solid flow.

[0067] It should be understood that the mixing pile machine 300 and the pulse unit 130 do not necessarily need to be started synchronously; their start-up and shutdown sequence can be flexibly set according to specific construction process requirements. In one embodiment, the mixing pile machine 300 starts the pulse unit 130 while drilling and mixing downwards, achieving simultaneous mixing and spraying. During the lifting and mixing stage, the pulse unit 130 is turned off, and only re-mixing is performed.

[0068] In one embodiment, to avoid dust from flying, the pulse unit 130 can be delayed in starting after the mixing pile machine 300 has drilled down into the soil layer, ensuring that the powder spraying operation is carried out in an underground closed environment.

[0069] In another embodiment, the mixing pile machine 300 first drills into the soil layer to a predetermined depth, and then activates the pulse unit 130 during the lifting and mixing process to achieve lifting, mixing and powder spraying.

[0070] Furthermore, this application is also compatible with common composite process modes in engineering practice, such as multi-cycle mixing and powder spraying combinations like "two-stage mixing and two-stage spraying," "four-stage mixing and two-stage spraying," and "four-stage mixing and four-stage spraying." Therefore, the start and stop timing of the mixing pile machine 300 and the pulse unit 130 can be adjusted according to engineering requirements, and this application does not impose any limitations on this.

[0071] Given that the height of the mixing pile machine 300 is typically over ten meters, the working pressure of the pressure hopper 120 needs to be maintained above 0.3 MPa to ensure a smooth supply of powder. However, higher working pressure is not always better. Excessive pressure not only places higher demands on the strength and sealing of the powder pipeline and connectors, but also leads to an excessively fast and uncontrollable powder flow rate, resulting in uneven mixing and reduced pile quality. Therefore, in actual construction, the pressure of the pressure hopper 120 is preferably controlled within the range of 0.3 MPa to 0.8 MPa to balance conveying efficiency and construction reliability.

[0072] In some embodiments, such as Figure 1 and Figure 3 As shown, the soft soil foundation powder spraying and mixing pile construction device also includes a storage mechanism 400. The storage mechanism 400 includes a storage tank 410 and a spiral auger 420. The bottom of the storage tank 410 is conical, and an opening 403 is provided at the bottom of the conical shape. The inlet of the spiral auger 420 is connected to the opening 403, and the outlet of the spiral auger 420 is connected to the feed inlet 121 at the top of the pressure ash tank 120. The spiral auger 420 has a spiral rod 404 inside, and a motor 405 is provided at one end of the spiral auger 420. The motor 405 is used to drive the spiral rod 404 to rotate, thereby conveying the dry cement powder in the storage mechanism 400 to the pressure ash tank 120. The control module 140 controls the start and stop of the motor 405 according to the preset weight of the dry cement powder. When the weight sensor 111 detects that the weight of the dry cement powder reaches or is close to the preset value, the control module 140 turns off the motor 405 and stops feeding. It should be noted that after the material is added, the actual weight of the dry cement powder in the pressure ash hopper 120 will usually deviate from the preset value by a certain margin. This error is about ±1%. This deviation is mainly caused by the signal fluctuation of the weight sensor 111 due to vibration, the hysteresis effect of some powder still falling in the air, and the deviation caused by the screw rod 404 adding material based on inertia after the motor stops. The weight deviation has no substantial impact on the subsequent quality of the powder spraying and mixing piles, and the construction process can still proceed normally.

[0073] In some embodiments, the outlet of the auger 420 is connected to the feed inlet 121 via a soft sleeve 406. The soft sleeve 406 can be a flexible sealing sleeve such as a braided sleeve or a film sleeve, used to isolate the weight of the auger 420 and the vibration during operation, preventing the vibration and weight from being transmitted to the pressure ash tank 120, thereby ensuring the measurement accuracy of the weighing sensor 111 at the bottom of the pressure ash tank 120 and preventing inaccurate powder metering due to interference.

[0074] In some embodiments, such as Figure 2As shown, the air compression mechanism 200 is connected to the pressurization port 124 of the pressure ash tank 120 via a three-way pipe 139. The three-way pipe 139 has three ports: the first port is connected to the air compression mechanism 200 and is equipped with a pressurization valve 132; the second port is connected to the pressurization port 124 of the pressure ash tank 120; and the third port is equipped with an exhaust valve 133, which is connected to an exhaust pipe 134. The control module 140 controls the opening and closing of the pressurization valve 132 and the exhaust valve 133. The pressurization valve 132 remains open during the pressurization of the pressure ash tank 120 and the operation of the pulse unit 130. After construction is completed or before adding cement dry powder, the control module 140 first closes the pressurization valve 132 and then opens the exhaust valve 133 to release pressure. After the pressure is released, the exhaust valve 133 is closed. If the feed valve 122 is opened directly without releasing pressure, the residual pressure in the pressure ash tank 120 may cause cement dry powder to spray back from the feed port, resulting in material waste and environmental pollution. Therefore, an exhaust valve 133 is installed to discharge the residual pressure in the pressure ash tank 120 through the exhaust pipe 134, ensuring that the pressure inside the tank drops to a safe level before proceeding with subsequent operations. To further reduce dust pollution during the exhaust process, the exhaust pipe 134 can be connected to a dust collection device such as a water tank or dust collection bag (not shown in the figure).

[0075] In some embodiments, such as Figure 2 As shown, a return valve 135 and an exhaust valve 134 are respectively installed on both sides of the third end of the three-way pipe. The control module 140 controls the opening and closing of the return valve 135 and the exhaust valve 134. The return valve 135 is connected to the pulse unit 130 through a pipeline. When the pressure tank 120 needs to be depressurized, and the pulse unit 130 completes the powder injection operation while the drill bit 350 of the mixing pile machine 300 is still in the soil layer, the control module 140 opens the return valve 135 to discharge the residual pressure in the pressure tank 120 into the underground soil layer through the pulse unit 130, avoiding the emission of dust gas to the surface and effectively reducing dust pollution. After the return valve 135 is depressurized, it is closed. To avoid incomplete depressurization of the pressure tank 120, the control module 140 can open the exhaust valve 133 again to vent the remaining pressure, ensuring operational safety and avoiding dust pollution.

[0076] In some embodiments, a pressure sensor 138 is provided on the pressure hopper 120. The pressure sensor 138 collects the pressure information of the pressure hopper 120 in real time and feeds it back to the control module 140. The control module 140 determines whether to start the pulse unit 130 or the pile mixing machine 300 or to perform a pressure relief operation based on the pressure information. At the same time, by continuously monitoring the pressure of the pressure hopper 120, the control module 140 ensures that the pressure in the pressure hopper 120 is maintained within the set working range, avoiding unstable gas-solid flow due to excessively high or low pressure, thereby ensuring the uniformity of cement dry powder spraying and the reliability of conveying.

[0077] In some embodiments, such asFigure 4 As shown, the mixing pile machine 300 is equipped with a depth sensor 321, which collects the drilling depth of the mixing pile machine 300 in real time and feeds it back to the control module 140; the control module 140 calculates the current drilling speed based on the rate of change of depth over time. Let the preset injection cycle of the pulse injection of pulse unit 130 be... Then, within a preset spraying cycle, the drilling distance of the mixing pile machine is 300. For the design depth of a single pile Total design cement dry powder usage The amount of powder required per unit depth can be obtained as follows: Therefore, the amount of dry cement powder to be supplied in each preset spraying cycle It can be represented as: The control mechanism 140 operates based on the real-time drilling speed. Dynamically calculate the required amount of dry cement powder within each preset spraying cycle. And achieve precise supply through any of the following methods:

[0078] ① Adjust the opening duration of the discharge valve 126 to ensure that the amount of discharged dry cement powder is consistent with the discharge amount. Match, close the discharge valve 126, and open the air inlet valve 129 to pressurize the pipeline.

[0079] ② Combining the weight signal of the pressure ash container 120 fed back by the weight sensor 111, when the weight reduction of the pressure ash container 120 approaches or reaches... When the time comes, close the discharge valve 126 and open the air inlet valve 129 to pressurize the pipeline.

[0080] The above-mentioned "spraying-pressurization" process is executed cyclically according to the preset spraying cycle, which not only ensures that the amount of cement dry powder used in the pile body reaches the design index, but also ensures that the amount of cement dry powder mixed at each depth of the entire pile body is uniform, realizing high-precision and adaptive powder supply control.

[0081] In some embodiments, when the drilling speed reported by the depth sensor 321 within a preset spraying cycle is zero or close to zero (e.g., less than 0.01 m / s), the control module 140 determines that the mixing pile machine 300 is in a stagnant state. At this time, in the next preset spraying cycle, the control module 140 automatically closes the discharge valve 126, stops the supply of dry cement powder, and controls the air inlet valve 129 to open intermittently to supplement compressed air into the powder pipeline to maintain a positive pressure state in the powder pipeline. This pressure-maintaining operation can effectively prevent powder settling or backflow of cement-soil mixture from the drill bit into the pipeline due to pressure loss, and can also ensure the uniform distribution of dry cement powder in the pile body. In actual construction, the mixing pile machine 300 often encounters isolated boulders, hard rock layers, or other abnormal geological obstacles and is temporarily unable to continue drilling. If powder spraying continues under such conditions, it will not only waste dry cement powder, but may also cause the actual dosage at that depth to far exceed the design value, thereby affecting the uniformity of cement dosage and pile quality of the entire pile body. Therefore, real-time feedback of drilling speed for dynamic start-stop powder injection is a key measure to achieve accurate metering and efficient construction.

[0082] In some embodiments, when the weight sensor 111 monitors the weight loss of the pressure ash tank 120 to measure the amount of discharged cement dry powder, it is easily affected by various factors such as vibration and high-pressure gas impact, resulting in a measurement deviation in the actual amount of cement dry powder discharged after the discharge valve 126 is closed. After calculating the deviation, the control module 140 dynamically compensates the amount of cement dry powder supplied in the next preset injection cycle of the pulse unit 130: if the actual discharge amount in the previous cycle is less than the target value... If the actual discharge in the previous cycle is greater than the target value, then the powder supply will be increased in the next cycle; If the error is not corrected, the powder supply will be reduced in the next cycle. Through the above error feedback and compensation mechanism, the system can correct deviations in real time, ensuring that the amount of dry cement powder is uniform along the depth direction of the entire pile, and achieving high-precision powder supply control.

[0083] In some embodiments, the preset injection cycle of the pulse unit 130 is set between 5 and 15 seconds, and the preset pulse cycle of the control valve 127 is set between 0.2 and 0.8 seconds. The specific duration of the preset injection cycle can be adaptively adjusted according to factors such as the soil properties of the construction site, the designed pile diameter, and the amount of dry cement powder used per pile, or adjusted according to the actual situation of the test pile. When the soil is relatively soft, the pile diameter is large, or the designed powder amount is high, the preset injection cycle is extended accordingly to deliver more dry cement powder within the cycle and to ensure that the air inlet valve 129 has sufficient time to complete effective pressure replenishment, avoiding pipeline blockage due to insufficient pressure replenishment caused by excessive discharge time. At the same time, the preset pulse cycle of the control valve 127 can also be adjusted according to the powder demand. When the amount of dry cement powder required according to the engineering design drawings or the actual situation of the test pile is large, the preset pulse cycle of the control valve 127 is shortened (i.e., the pulse frequency is increased) to slow down the instantaneous flow rate of the powder, prevent the powder from rushing into the pipeline and causing blockage, and maintain a stable pulsed gas-solid flow.

[0084] In some embodiments, after construction is completed, the control module 140 automatically saves key data such as the drilling depth, actual powder consumption, and spraying cycle parameters of each pile, providing reliable data support for subsequent quality traceability, pile quality assessment, and construction process optimization.

[0085] In some embodiments, a pressure gauge 137 is provided on the pressure ash tank 120, and a pressure gauge is also provided on the air compression mechanism 200. Both are used to observe pressure information, and the pressure difference between the two can be used to determine whether there are problems such as air leakage or pressure sensor failure in the air supply pipeline.

[0086] In some embodiments, the air compression mechanism 200 is connected to the pressurization port 124 and the air inlet 125 through the air distribution box 136 to ensure that the pressure of the pressure ash tank 120 is consistent with the pressure of the air inlet.

[0087] In some embodiments, the feed valve 122, discharge valve 126, control valve 127, air inlet valve 129, pressurization valve 132, exhaust valve 133, and return valve 135 are all pneumatic valves, which are connected to the air distribution box 136 through pipelines. The control module 140 controls the opening and closing of the pipeline through a solenoid valve (not shown in the figure).

[0088] It should be understood that the control module 140 also includes a human-machine interaction unit, which is used to display the data collected by the depth sensor 321, weight sensor 111 and pressure sensor 138 in real time, and provides an operation interface for construction personnel to set process parameters such as preset spraying cycle, preset pulse cycle, target powder quantity, and pressure threshold, as well as specific functions such as manually starting and stopping the pulse unit 150, the feed valve 122 or the mixing pile machine 300; the control module 140 can be implemented using an industrial control computer, PLC or embedded system, and the control program running inside it is based on conventional logic programming (such as ladder diagram, C language or Python script) to perform data acquisition, logical judgment and valve timing control, which is a well-known technology that can be directly implemented by those skilled in the art.

[0089] This application also provides a method for constructing powder jet grouting piles on soft soil foundations, implemented using a construction device based on any of the foregoing embodiments of this specification, specifically including the following steps:

[0090] S1. Before construction, level the work site and install and position the material supply mechanism 100, air compression mechanism 200, and mixing pile machine 300. Complete the system connection through air pipeline and powder pipeline.

[0091] S2. Add the required dry cement powder to the high-pressure tank 120. The control mechanism 140 obtains the weight of the dry cement powder or the total weight of the pressure tank 120 through the weight sensor 111.

[0092] S3. Start the air compressor 200 to fill the pressure ash tank 120 with compressed gas until the pressure inside the pressure ash tank 120 reaches the pre-working pressure.

[0093] S4. Then, start the mixing pile machine 300 to drill into the soil layer and mix it simultaneously; according to the design requirements, the control module 140 starts the pulse unit 130.

[0094] S5. During the continuous mixing and drilling process of the mixing pile machine (300), the air compression mechanism (200) continuously supplies air to the pressure ash tank (120) to stabilize the tank pressure, and the control module (140) performs the following operations in a preset spraying cycle:

[0095] S501. Open the discharge valve 126 to allow the cement dry powder to be discharged under the action of air pressure inside the tank;

[0096] S502, the synchronous control valve 127 repeatedly opens and closes with a preset pulse cycle to achieve intermittent powder supply, form a pulsed gas-solid flow, and push the powder to be conveyed to the mixing pile machine 300;

[0097] S503. When the weight sensor 111 feedback that the powder weight loss reaches the target value, or when the discharge valve 126 is open for a set duration, the discharge valve 126 is closed.

[0098] S504. Then open the air intake valve 129 to supplement compressed air into the powder pipeline, push the dry cement powder in the powder pipeline and maintain the pressure.

[0099] S505. After the pressure is replenished, proceed to the next preset spraying cycle and repeat the above process until the mixing pile machine 300 drills to the design depth or completes the mixing operation.

[0100] S6. The mixing pile machine 300 moves to the next pile location and repeats the process steps S2 to S5 or S4 to S5 to construct the next pile. That is, depending on the remaining amount of cement powder in the high-pressure tank 120, whether to add cement powder is required. If the amount of cement powder in the high-pressure tank 120 is sufficient for the construction requirements of the next pile, the steps S4 to S5 can be repeated directly to construct the next pile.

[0101] Example 1

[0102] The following embodiment, with reference to the accompanying drawings, is applied to a soft soil foundation reinforcement project for a highway in a coastal city in Zhejiang Province. The area's subsurface soil is primarily silty clay with an average moisture content exceeding 60%, making it suitable for foundation treatment using a jet grouting and mixing pile process. The design employs a bidirectional mixing, two-stage mixing and one-stage spraying process (i.e., mixing and spraying powder during the downward movement, followed by re-mixing without spraying during the upward movement). The piles are arranged in a quincunx pattern to form a continuous reinforcement zone. The design parameters for a single pile are as follows: pile length 21m, pile diameter 0.5m, using 42.5 grade ordinary Portland cement with an admixture of 18%, and the amount of dry cement powder used per cubic meter of subsurface soil at the construction site is approximately 1800 kg, resulting in a single pile dry cement powder consumption of approximately 1344 kg (64 kg / m).

[0103] The construction equipment used includes:

[0104] Mixing pile machine 300: The overall height of the machine is 24 m, equipped with a dual-shaft bidirectional mixing drill rod 340 and drill bit 350, with a total length of 25 m, and driven by a 55kW single motor power head 330;

[0105] Air compression mechanism 200: including a 37kW air compressor 210 (rated exhaust pressure 0.8Mpa, exhaust volume 6m³ / min), a 1 m³ air tank 220 and a 20AC (20m³ / min) refrigerated dryer 230;

[0106] Material feeding mechanism 100: Pressure ash hopper 120 has a volume of 3m³ and a rated dry cement powder weight of 4000kg. It is mounted on bracket 110 with three weight sensors 111 and three-legged support.

[0107] Storage mechanism 400: Cylindrical feeding tower, connected to the inlet 121 of pressure ash tank 120 via spiral auger 420.

[0108] Before construction, the site was leveled, all equipment was positioned and installed, and connected via pipelines. After power was connected, the air compressor 200 pre-pressurized the air storage tank 220. Based on the test pile data and design requirements, the following parameters were set via the control module 140:

[0109] Pressure ash silo 120 with a weight of 3900 kg

[0110] Target weight of dry cement powder for a single pile: 1344 kg;

[0111] The preset injection cycle of pulse unit 130 is 8 seconds.

[0112] Powder content per unit depth: 64 kg / m;

[0113] The preset pulse period for control valve 127 is 0.4s.

[0114] Subsequently, the control module 140 initiates the cement dry powder filling procedure: the feed valve 122 is opened, and the screw conveyor motor 405 is started to deliver cement dry powder to the pressure ash hopper 120; when the weight sensor 111 indicates that the powder in the hopper has reached 3900 kg, the motor 405 is automatically stopped and the feed valve 122 is closed. After filling is completed, the actual filling amount is 3910 kg as obtained by the weight sensor 111 (the deviation is within the allowable range).

[0115] Next, the pressurization valve 132 is opened to pressurize the pressure ash tank 120. When the pressure inside the tank reaches 0.5 MPa, the mixing pile machine 300 is started to drill downwards, and at the same time, the pulse unit 130 is activated by the control module 140 to start synchronous powder spraying and mixing. The air compression mechanism 200 continuously supplies air to maintain the tank pressure stable above 0.5 MPa.

[0116] During drilling, pulse unit 130 performs the following operations in an 8-second cycle:

[0117] (1) Open the discharge valve 126 and the cement dry powder is discharged under air pressure; (2) Control valve 127 is opened and closed intermittently at a cycle of 0.4 seconds to form a pulse air-solid flow and promote stable conveying of powder; (3) When the discharge time reaches the set value or the weight reduction is close to the target amount, close the discharge valve 126; (4) Then open the air inlet valve 129 to pressurize the powder pipeline, push the residual powder and prevent pressure loss and blockage.

[0118] The control module 140 combines the feedback data from the depth sensor 321 and the weight sensor 111 in real time to dynamically calculate the amount of powder to be supplied in each preset spraying cycle, and compensates for the weighing error of the previous cycle in the next cycle to ensure that the amount of powder is uniform along the pile depth direction.

[0119] Once the drill bit reaches the designed depth (21m), close the discharge valve 126 and control valve 127 to stop powder spraying; the mixing pile machine 300 switches to lifting and re-mixing mode. During this stage, the air inlet valve 129 continues to open intermittently as needed to maintain the pressure in the powder pipeline and push the residual powder to the drill bit to avoid blockage.

[0120] After a single pile is completed, the weight sensor reports a cement balance of 2564 kg in the pressure mortar hopper 120. The control module 140 stores key data: actual powder consumption of 1246 kg and pile depth of 21.2 m. The control module 140 archives parameters such as mixing speed, powder quantity, and depth for quality traceability and process optimization.

[0121] The mixing pile machine 300 moves to the next pile location for construction and continues the above steps. When the pressure mortar tank 120 needs to continue adding cement dry powder, before the drill bit is pulled out of the ground, the pressure mortar tank 120 is depressurized: the control module 140 first closes the pressure valve 132, then opens the return valve 135 to discharge the residual pressure into the soil layer through the injection port 352; then the exhaust valve 133 is opened to completely empty the remaining pressure in the tank, and then the cement dry powder injection program is started to ensure safety.

[0122] In summary, the beneficial technical effects brought about by this invention include:

[0123] (1) By controlling the opening and closing sequence of the discharge valve 126, control valve 127 and air inlet valve 129 of the pulse unit 130 according to the preset spraying cycle, the control module 140 can achieve quantitative powder supply in each preset spraying cycle, which can effectively ensure the amount of cement dry powder used in the pile body and the uniformity of cement dry powder content along the depth direction of the pile body, and at the same time can effectively avoid powder accumulation or pipeline blockage caused by continuous powder supply.

[0124] (2) The preset pulse cycle of the control valve 127 opens and closes, forming an intermittent interception of cement dry powder when the discharge valve 126 is open, and works in conjunction with the pressure replenishment of the air inlet valve 129 to form a stable pulse gas-solid flow in the powder conveying pipeline, which not only prevents excessive concentrated spraying of powder, but also ensures sufficient powder pushing, significantly improving the conveying stability and uniformity.

[0125] (3) Combining the real-time monitoring of the weight of the high-pressure tank 120 by the weight sensor 111 and the dynamic feedback of the drilling speed by the depth sensor 321, the control module 140 can accurately calculate the amount of dry cement powder required for each cycle, and achieve precise powder supply on demand by adjusting the opening time of the discharge valve (126) or closing the valve based on the weighing signal.

[0126] (4) Furthermore, the system can automatically compensate and adjust in the next cycle based on the weighing error of the previous cycle, effectively suppressing the cumulative deviation and ensuring better uniformity of cement dry powder content along the depth direction of the entire pile.

[0127] (5) After construction is completed, the control module 140 automatically saves key data such as drilling depth, actual powder consumption, and spraying cycle parameters for each pile, providing reliable data support for subsequent quality traceability, pile quality assessment and construction process optimization.

[0128] The construction method in this embodiment is the same as that in the specific implementation method, and will not be described again.

[0129] In this specification, the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the descriptions of the embodiments described later are relatively simple, and relevant parts can be referred to the descriptions of the foregoing embodiments.

[0130] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A construction device for powder jet grouting and mixing piles in soft soil foundation, comprising a feeding mechanism (100), an air compression mechanism (200), and a mixing pile machine (300); characterized in that: The feeding mechanism (100) includes a support (110), a pressure ash tank (120), and a control module (140); the pressure ash tank (120) is connected to the air compression mechanism (200) via an air supply pipeline; a pulse unit (130) is connected to the lower end of the pressure ash tank (120), the pulse unit (130) includes a pulse tube (123), and a discharge valve (126), a control valve (127), and a spray nozzle (128) sequentially arranged on the pulse tube (123) along the cement dry powder conveying direction; the spray nozzle (128) is connected to the mixing pile machine (300) via a powder pipeline, and the pulse tube (126) between the control valve (127) and the spray nozzle (128) is connected to the control valve (127) and the spray nozzle (128). 3) An air inlet (125) is provided on the upper part, and an air inlet valve (129) is provided at the air inlet (125). The air inlet valve (129) is connected to the air compression mechanism (200) through an air supply pipeline. The control module (140) is configured to control the opening and closing sequence of the discharge valve (126), control valve (127) and air inlet valve (129) in a preset injection cycle. In a preset injection cycle, when the discharge valve (126) is open, the control valve (127) repeatedly opens and closes according to a preset pulse cycle to achieve intermittent powder supply. When the discharge valve (126) is closed, the air inlet valve (129) opens to pressurize the powder pipeline so as to form a periodic pulse gas-solid flow in the powder pipeline.

2. The soft soil foundation powder jet mixing pile construction device according to claim 1, characterized in that: The support (110) is equipped with a weight sensor (111), and the pressure ash tank (120) is fixedly connected to the support (110) through the weight sensor (111). The weight sensor (111) feeds back the collected weight signal to the control module (140) in real time. The control module (140) dynamically adjusts the opening duration of the discharge valve (126) according to the weight information fed back by the weight sensor (111) to realize the quantitative supply of cement dry powder.

3. The soft soil foundation powder jet mixing pile construction device according to claim 2, characterized in that: The mixing pile machine (300) is equipped with a depth sensor (321). The depth sensor (321) collects the drilling depth of the mixing pile machine (300) in real time and feeds it back to the control module (140). The control module (140) calculates the current drilling speed based on the rate of change of depth over time. Based on the real-time drilling speed, the control module (140) dynamically calculates the amount of dry cement powder required in each spraying cycle. The control module (140) achieves precise powder supply through any of the following methods: Adjust the opening duration of the discharge valve (126) to match the amount of discharged powder with the required amount of dry cement powder; Alternatively, in conjunction with the weight signal of the pressure ash jar (120) fed back by the weight sensor (111), when the weight reduction of the pressure ash jar (120) reaches the required amount of dry cement powder, the discharge valve (126) is closed.

4. The soft soil foundation powder jet mixing pile construction device according to claim 3, characterized in that: The control module (140) calculates the deviation between the weight reduction value of the current preset spraying cycle and the target amount of dry cement powder based on the weight information fed back by the weight sensor (111) after the discharge valve (126) is closed. Based on this deviation, the control module (140) adjusts the opening time of the discharge valve (126) or the weight of dry cement powder in the next cycle.

5. The soft soil foundation powder jet mixing pile construction device according to claim 4, characterized in that: The preset injection cycle of the pulse unit (130) is 5 to 15 seconds, and the preset pulse cycle of the control valve (127) is 0.2 to 0.8 seconds.

6. The soft soil foundation powder jet mixing pile construction device according to claim 4, characterized in that: When the drilling speed fed back by the depth sensor (321) is zero or close to zero within a certain preset spraying cycle, the control module (140) determines that the mixing pile machine (300) is in a stagnant state. At this time, in the next preset spraying cycle, the control module (140) automatically closes the discharge valve (126), stops the supply of dry cement powder, and controls the air inlet valve (129) to open, supplementing compressed air to the powder pipeline to maintain the positive pressure state in the powder pipeline.

7. The soft soil foundation powder jet mixing pile construction device according to claim 2, characterized in that: It also includes a storage mechanism (400), which includes a storage tank (410) and a spiral auger (420). One end of the spiral auger (420) is connected to the storage tank (410), and the other end is connected to the pressure ash tank (120) through a soft sleeve (406). The spiral auger (420) has a spiral rod (404) inside, and a motor (405) is provided at one end of the spiral auger (420). The pressure ash tank (120) is provided with a feed valve (122), and the control module... The control module (140) controls the opening and closing of the motor (405) and the feed valve (122). When cement dry powder needs to be added, the control module (140) opens the feed valve (122) and starts the motor (405) so that the screw conveyor (420) delivers cement dry powder to the pressure ash tank (120). When the amount of material added fed by the weight sensor (111) reaches the preset value, the control module (140) shuts down the motor (405) and the feed valve (122).

8. The soft soil foundation powder jet mixing pile construction device according to claim 4, characterized in that: The air compression mechanism (200) is connected to the pressure ash tank (120) through a three-way pipe (139). The three-way pipe (139) has three ports. The first port is connected to the air compression mechanism (200) and is equipped with a pressurizing valve (132). The second port is connected to the pressure ash tank (120). The third port is equipped with an exhaust valve (133). The exhaust valve (133) is connected to an exhaust pipe (134). The control module (140) controls the opening and closing of the pressurizing valve (132) and the exhaust valve (133). When the pressure ash tank (120) is depressurized, the control module (140) first closes the pressurizing valve (132) and then opens the exhaust valve (133) to depressurize. After the depressurization is completed, the exhaust valve (133) is closed.

9. A construction device for powder jet grouting and mixing piles on soft soil foundation according to claim 8, characterized in that: The third end of the three-way pipe (139) is provided with a return valve (135) and an exhaust valve (134) on both sides respectively. The control module (140) controls the opening and closing of the return valve (135) and the exhaust valve (134). The return valve (135) is connected to the pulse unit (130) through a pipeline. When the pressure ash tank (120) is depressurized, the control module (140) first closes the pressurizing valve (132), opens the return valve (135) to depressurize the powder pipeline, and finally opens the exhaust valve (133) to empty the pressure of the pressure ash tank (120).

10. The soft soil foundation powder jet mixing pile construction device according to claim 1, characterized in that: When the mixing pile machine (300) performs dry mixing operation in the soil layer, the discharge valve (126) is closed and the powder supply is stopped; the control module (140) controls the air inlet valve (129) to open and close in a pulse manner to intermittently supplement compressed air to the powder pipeline to maintain the positive pressure state in the powder pipeline.

11. A method for constructing powder jet grouting piles on soft soil foundations, specifically including the following steps: S1. Before construction, level the work site and install and position the material supply mechanism (100), air compression mechanism (200), and mixing pile machine (300), and complete the system connection through the air pipeline and powder pipeline; S2. Add the required dry cement powder to the pressure ash jar (120). The control mechanism (140) obtains the weight of the dry cement powder or the total weight of the pressure ash jar (120) through the weight sensor (111). S3. Start the air compressor (200) to fill the pressure tank (120) with compressed gas until the pressure inside the pressure tank (120) reaches the preset working pressure; S4. Start the mixing pile machine (300) to drill into the soil layer and mix synchronously; according to the design requirements, the control module (140) starts the pulse unit (130); S5. During the continuous mixing and drilling process of the mixing pile machine (300), the air compression mechanism (200) continuously supplies air to the pressure ash tank (120) to stabilize the tank pressure, and the control module (140) performs the following operations in a preset spraying cycle: S501, open the discharge valve (126) to allow the cement dry powder to be discharged under the action of air pressure inside the tank; S502, the synchronous control valve (127) repeatedly opens and closes with a preset pulse cycle to achieve intermittent powder supply, form a pulsed gas-solid flow, and push the powder to be conveyed to the mixing pile machine (300); S503, when the weight loss of powder reported by the weight sensor (111) reaches the target value, or when the opening time of the discharge valve (126) reaches the set duration, the discharge valve (126) is closed. S504, then the air intake valve (129) is opened to supplement compressed air into the powder pipeline, push the cement dry powder in the powder pipeline and maintain the pressure; S505, after the pressure is replenished, enter the next preset spraying cycle and repeat the above process until the mixing pile machine (300) drills to the design depth or completes the mixing operation; S6. Move the mixing pile machine (300) to the next pile position and repeat the above S4 to S5 or S2 to S5 process steps to construct the next pile.

12. The method for constructing powder jet grouting piles on soft soil foundation according to claim 11 further includes the following steps: A depth sensor (321) is installed on the mixing pile machine (300). The depth sensor (321) collects the drilling depth of the mixing pile machine (300) in real time and feeds it back to the control module (140). The control module (140) calculates the current drilling speed based on the rate of change of depth over time. The control mechanism (140) dynamically calculates the amount of dry cement powder required in each preset spraying cycle based on the real-time drilling speed. The control module (140) achieves precise powder supply through any of the following methods: Adjust the opening duration of the discharge valve (126) to match the amount of discharged powder with the required amount of dry cement powder; Alternatively, in conjunction with the weight reduction signal of the pressure ash jar (120) fed back by the weight sensor (111), when the weight reduction of the pressure ash jar (120) reaches the required amount of dry cement powder, the discharge valve (126) is closed.

13. The method for constructing powder jet grouting piles on soft soil foundation according to claim 11 or 12 further includes the following steps: The control module (140) calculates the deviation between the weight reduction value of the current preset spraying cycle and the target amount of dry cement powder based on the weight information fed back by the weight sensor (111) after the discharge valve (126) is closed. Based on this deviation, the control module (140) adjusts the opening time of the discharge valve (126) or the weight of dry cement powder in the next cycle.

14. The method for constructing powder jet grouting piles on soft soil foundation according to claim 11 further includes the following steps: The single preset injection cycle of the pulse unit (130) is set to 5 to 15 seconds, and the preset pulse cycle of the control valve (127) is set to 0.2 to 0.8 seconds.

Images