Multi-depth mud sampling device for cast-in-place piles

Abstract

The utility model relates to the technical field of bored pile construction, especially a bored pile multi-depth mud sampling device. The device comprises a bin body, the bottom of the bin body is provided with a detachable counterweight for facilitating sinking and unloading after sampling; a slurry inlet is formed in the upper side wall and sealed by a plug; the device further comprises a pressure chamber integrally formed on the bin top, a piston and a piston rod are arranged in the pressure chamber, the piston rod extends into the bin and is connected to multiple support rods, the outer ends of the support rods are connected to the plug; a ground air pump is connected to the air inlet at the top of the pressure chamber through an air inlet pipe, the air supply can drive the piston and the piston rod to move downward, and then the plug is opened through linkage of the support rods to take samples; a pressure sensor is mounted on the bin top, depth data are uploaded in real time through a cable, and the steel cable bears the functions of suspension and lifting of the whole device, and finally remote, accurate and layered sampling of undisturbed mud at different depths is realized.

Description

Technical Field

[0001] This utility model relates to the field of bored pile construction technology, and in particular to a multi-depth mud sampling device for bored cast-in-place piles. Background Technology

[0002] Drilled piles, as a key foundation type, are widely used in construction, bridges, foundation pit support, and water conservancy projects due to their advantages such as convenient construction, strong adaptability, and high bearing capacity. During drilling, mud wall protection technology is crucial. It effectively prevents hole collapse and ensures the quality of the drilled hole by forming a mud cake on the hole wall, carrying drill cuttings, cooling the drill bit, and stabilizing the pressure inside the hole.

[0003] The performance indicators of drilling mud, such as density, viscosity, and sand content, directly affect its wall protection effect and the final quality of pile foundation formation. Theoretically, stratified sampling and testing of drilling mud at different borehole depths are necessary to accurately and comprehensively evaluate its actual working state within the borehole. This is because: strata vary along the borehole depth, and different soil layers (such as clay, sand, and gravel layers) have different performance requirements and influences on the drilling mud, resulting in a non-uniform distribution of mud properties in the vertical direction; in forward / reverse circulation processes, the drilling mud carries drill cuttings back to the surface from the bottom of the borehole, and the sand content, specific gravity, and other indicators of the mud at the bottom of the borehole usually differ significantly from those of the upper mud.

[0004] Current methods for testing drilling mud quality have significant limitations. Currently, construction sites generally lack dedicated deep sampling equipment, typically obtaining mixed mud samples only near the borehole opening or by mixing all the mud in the borehole before sampling. These methods cannot avoid the mixing of mud from different depths, resulting in samples that are severely lacking in representativeness and failing to accurately reflect the mud properties in critical areas within the borehole. Test results based on such mixed samples are insufficient to effectively guide mud performance adjustments and borehole cleaning operations, creating potential risks to project quality. If construction is based on unrepresentative test results, improper mud performance control can easily lead to a series of engineering problems, such as: excessive sediment at the bottom of the borehole causing a decrease in pile bearing capacity; incomplete mud replacement causing defects such as mud inclusions and pile breakage; or insufficient mud wall protection leading to borehole collapse risks.

[0005] Therefore, developing a device that can accurately and conveniently perform sealed sampling at different specified depths within the borehole to obtain unmixed, undisturbed, layered mud samples is of urgent engineering need and significant practical value for scientifically evaluating mud performance, guiding the optimization of construction parameters, and ultimately ensuring the quality of bored piles. Utility Model Content

[0006] The technical problem to be solved by this utility model is: in order to solve the problem that the existing technology in the background art does not have equipment for stratified sampling, and the mud samples taken are near the borehole or mixed samples, and the test results cannot be used as a reliable basis for evaluating the mud condition, a multi-depth mud sampling device for bored piles is provided.

[0007] The technical solution adopted by this utility model to solve its technical problem is as follows: a multi-depth mud sampling device for bored piles, including a chamber, a mud sampling port at the lower end of the chamber, a counterweight block detachably connected to the mud sampling port, an integrally formed pressure chamber at the top of the chamber, a piston rod slidably disposed in the pressure chamber, a piston fixed at the upper end of the piston rod, and its lower end extending downward into the pressure chamber and into the interior of the chamber, a plurality of support rods on the outer peripheral wall of the lower end of the piston rod, the other end of the support rods being connected to a plug for sealing the mud inlet, a mud inlet adapted to the plug being opened on the upper side wall of the chamber, an air inlet being opened at the top of the pressure chamber, the air inlet being connected to an air pump through an air inlet pipe; a steel cable and a cable fixing buckle are also connected to the top of the chamber, the end of the cable being electrically connected to a pressure sensor installed on the top of the chamber.

[0008] The chamber is used to hold and extract mud samples, with the intake port serving as the sample outlet, facilitating the complete and convenient export of mud samples from the chamber to an external container for testing. A counterweight provides sufficient weight to ensure the entire sampling device can overcome buoyancy and resistance in dense mud, quickly and stably sinking to the predetermined depth. The piston moves linearly within the pressure chamber under air pressure, and the piston rod precisely transmits this linear motion to the interior of the chamber. Evenly distributed support rods convert this linear motion into radial motion. As the piston rod descends, the support rods are pushed open, thus opening the intake port. An air pump serves as a remote power source, providing stable and controllable air pressure. Steel cables handle suspension, lowering, and lifting. Cables transmit electrical signals, sending real-time sensor signals from the top of the chamber to the ground operating platform, providing operators with information such as depth and status.

[0009] According to one embodiment of the present invention, the side wall of the silo body is divided into an upper side section and a lower side section from top to bottom. The upper side section is inclined outward, and the slurry inlet is opened on the upper side section. The lower side section is connected to the lower end of the upper side section and is inclined inward to form a constriction that cooperates with the counterweight.

[0010] The upper section slopes outwards, increasing the effective opening area of ​​the slurry inlet. When open, this structure reduces resistance to slurry flow, allowing it to fill the chamber more quickly and smoothly, obtaining samples closer to their original shape and improving sampling efficiency. The lower section slopes inwards, forming a tapering opening that facilitates a smooth linear connection with the counterweight, reducing fluid resistance during sinking. It also provides guidance and a mating surface for the counterweight installation, resulting in a more rational structure.

[0011] According to one embodiment of the present invention, a plurality of pressure sensors are installed on the top surface of the chamber.

[0012] Setting up multiple pressure sensors can serve as an average calculation and redundancy backup. By calculating the average readings of multiple sensors, more accurate and stable depth data can be obtained, reducing errors caused by the failure of a single sensor or fluctuations in readings.

[0013] According to one embodiment of the present invention, the inner wall of the slurry intake port is provided with an internal thread; the top of the counterweight is provided with a connecting section that mates with the closing end, the outer wall of the connecting section is provided with an external thread that mates with the internal thread, and the bottom surface of the counterweight is an arc surface that facilitates sinking.

[0014] The threaded connection can withstand greater tension and torque, ensuring that the counterweight will not fall off accidentally during lifting. The detachable connection also facilitates maintenance and replacement of counterweights of different weights to adapt to different working conditions.

[0015] According to one embodiment of the present invention, the upper top wall of the pressure chamber is an arched structure, and its lower half extends into the interior of the chamber.

[0016] When subjected to internal air pressure, the arched surface can evenly distribute the pressure to the entire cavity wall, avoiding stress concentration at right angles or flat angles.

[0017] According to one embodiment of the present invention, the number of support rods is 4, and the silo body is provided with 4 slurry inlets.

[0018] The symmetrical distribution at four points ensures uniform force on the piston rod, preventing skewing and jamming, and making the opening and closing action smoother and more reliable. At the same time, the four inlets provide a large flow area when open, ensuring rapid mud entry.

[0019] According to one embodiment of the present invention, the cable is covered with a waterproof protective sleeve.

[0020] The drilling mud environment is harsh, corrosive, and under great pressure. The waterproof sleeve can effectively protect the internal cable core from the erosion of mud and water vapor as well as physical scratches, ensuring that the electrical signal of the pressure sensor can be transmitted stably over long distances without attenuation or interference, thus guaranteeing the accuracy of depth monitoring data.

[0021] According to one embodiment of the present invention, the air pump is disposed on an operating platform, and the operating platform is further provided with a gantry frame, on which a rotating roller driven by a power device is installed, and the steel cable and wire are wound around the rotating roller.

[0022] The rotating roller driven by the power unit enables the synchronous and automatic winding and unwinding of steel cables and wires, achieving uniform and precise lowering and lifting.

[0023] The beneficial effects of this utility model are: The controllable opening and closing mechanism, consisting of an air pump, pressure chamber, piston rod, support rod, and plug, ensures that the slurry inlet remains completely closed during the sinking process. It is only remotely triggered by ground personnel when the preset target depth is accurately reached, thus preventing the upper layer of mud from mixing into the chamber during the sinking process. By monitoring the mud at different depths, the condition of sediment at the bottom of the hole and the properties of the mud can be accurately grasped. Powered by an air pump and with integrated transmission via steel cables and wires, all critical operations can be performed remotely on a ground-based operating platform, reducing manpower and human error, and resulting in high sampling efficiency. The slurry inlet is located on the outward-sloping upper side, increasing the sampling entrance area and allowing the slurry to fill the chamber quickly and smoothly. The multiple pressure sensors can improve depth measurement accuracy through data fusion and have redundancy backup function. The threaded counterweight is easy to disassemble, facilitating sampling and replacement. The arched top surface of the pressure chamber can evenly distribute air pressure stress. The symmetrical design of 4 support rods and 4 slurry inlets ensures uniform force on the piston rod, smooth transmission, avoids jamming, and ensures the reliability of opening and closing actions. The waterproof sleeve of the cable ensures stable transmission of sensor signals in high-pressure and corrosive slurry environments. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Figure 1 This is a schematic diagram of the working process of this utility model.

[0026] Figure 2 This is a schematic diagram of the structure of this utility model.

[0027] Figure 3 This is a schematic diagram of the rotating roller in this utility model.

[0028] Figure 4 This is a schematic diagram of the counterweight block in this utility model.

[0029] In the diagram: 1. Silo body; 101. Upper side section; 102. Lower side section; 11. Slurry inlet; 12. Pressure chamber; 121. Air inlet; 13. Piston rod; 14. Piston; 15. Support rod; 16. Slurry inlet; 17. Plug; 2. Counterweight; 21. Connecting section; 3. Air inlet pipe; 4. Air pump; 5. Steel cable; 6. Cable; 7. Pressure sensor; 8. Operating platform; 9. Gantry frame; 10. Rotating roller. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.

[0031] like Figure 2 As shown, a multi-depth mud sampling device for bored piles includes a chamber 1. A mud sampling port 11 is located at the lower end of the chamber 1, and a counterweight 2 is detachably connected to the mud sampling port 11. An integrally formed pressure chamber 12 is located at the top of the chamber 1. A piston rod 13 is slidably disposed within the pressure chamber 12. A piston 14 is fixed to the upper end of the piston rod 13, and its lower end extends downwards into the pressure chamber 12 and into the chamber 1. Four support rods 15 are provided on the outer peripheral wall of the lower end of the piston rod 13. The other end of each support rod 15 is connected to a sealing device. The slurry inlet 16 has a plug 17, and the upper side wall of the chamber 1 has a slurry inlet 16 that is compatible with the plug 17. The top of the pressure chamber 12 has an air inlet 121, which is connected to the air pump 4 through the air inlet pipe 3. The top of the chamber 1 is also connected to the fixing buckle of the steel cable 5 and the cable 6. The end of the cable 6 is electrically connected to the pressure sensor 7 installed on the top of the chamber 1, and the cable 6 is covered with a waterproof protective sleeve. The protection level of the pressure sensor 7 is ≥IP68, and the connection with the cable 6 adopts a waterproof structure.

[0032] The chamber 1 serves as the sample container, the slurry inlet 11 is the final outlet for the sample, and the counterweight 2 provides downward force. It is detachably connected, allowing for easy removal and sample extraction after sampling. The pressure chamber 12, integrally molded onto the chamber 1, ensures seamless connection between the pressure chamber 12 and the chamber 1, providing extremely high sealing performance and structural strength. The piston 14 and piston rod 13 convert pneumatic power into linear motion, while the support rod 15 converts linear motion into radial motion. The plug 17 performs the sealing / opening action. Pneumatic pressure pushes the piston rod 13 downward, pulling the plug 17 out of the slurry inlet 16 via the support rod 15. After depressurization, under gravity or mud pressure, the piston rod 13 rises, the support rod 15 retracts, and the plug 17 re-seals the slurry inlet 16.

[0033] An operating platform 8 is provided at the top of the bored pile. An air pump 4 and a gantry frame 9 are mounted on the operating platform 8. A rotating roller 10 driven by a power unit is installed on the gantry frame 9. Steel cables 5 and wire cables 6 are wound around the rotating roller 10. Figure 3 As shown, steel cable 5 and cable 6 are wound around the left and right sections of rotating roller 10 respectively. A partition is provided in the middle of rotating roller 10 to prevent the two types of cables from getting mixed up.

[0034] The operating platform 8 provides a stable and safe working area. All ground equipment is integrated on the operating platform 8. The gantry frame 9 is used to support and guide the cable. The power unit drives the rotating roller 10 to achieve uniform and smooth lowering and lifting of the device. Uniform lowering is crucial for the pressure sensor 7 to read stable and accurate depth data. The baffle ensures that the steel cable 5 and the cable 6 are synchronized but separated during the winding and lowering process, avoiding damage to the cable 6, signal interruption, or even jamming caused by mutual squeezing, tangling, and friction between the steel cable 5 and the cable 6.

[0035] Specifically, the sidewall of the silo 1 is divided into an upper sidewall 101 and a lower sidewall 102 from top to bottom. The upper sidewall 101 slopes outward, and the slurry inlet 16 is located on the upper sidewall 101. The lower sidewall 102 is connected to the lower end of the upper sidewall 101 and slopes inward to form a constricted opening that cooperates with the counterweight 2. Several pressure sensors 7 are installed on the top surface of the silo 1.

[0036] The outward-sloping upper side 101 increases the effective opening area of ​​the slurry inlet 16. When the plug 17 is open, it reduces the resistance to slurry flow, allowing the chamber 1 to be rapidly filled in a very short time, thereby obtaining a sample that more accurately represents the instantaneous state at that depth and improving sampling efficiency. The constricted lower side 102 reduces resistance during the device's descent, enabling it to reach the target depth more quickly. It also serves as a guide and positioning structure, making alignment and tightening easier when connected to the counterweight 2, thus optimizing the assembly process. The arrangement of multiple sensors is an effective means of achieving measurement redundancy and improving accuracy. If one sensor fails, the system can still operate normally, improving the equipment's fault tolerance and reliability.

[0037] The inner wall of the slurry inlet 11 is provided with internal threads; such as Figure 4 As shown, the top of the counterweight 2 is provided with a connecting section 21 that matches the constriction, the outer side wall of the connecting section 21 is provided with an external thread that matches the internal thread, and the bottom surface of the counterweight 2 is an arc surface that facilitates sinking.

[0038] The threaded connection can withstand enormous tensile forces and vibrations, ensuring that the counterweight 2 will not loosen in complex downhole environments. The precision-machined threaded mating surface itself can also effectively seal the slurry sampling port 11, preventing slurry from seeping into the chamber 1 from the bottom and contaminating it before sampling. The curved surface can effectively reduce the resistance at the bottom when the device descends and prevent the bottom from scraping against obstacles on the borehole wall, making the descent process smoother. It also helps to reduce the agitation of the slurry in the borehole during the device's lifting, avoiding damage to the borehole wall.

[0039] Preferably, the upper top wall of the pressure chamber 12 has an arched structure, and its lower half extends into the interior of the chamber body 1.

[0040] When compressed air is pumped into the pressure chamber 12 by the air pump 4, the internal pressure increases. The arched top cover can evenly distribute the pressure along the curved surface to the entire sidewall of the chamber, thereby minimizing stress concentration at flat tops or right-angle joints. This enhances the pressure chamber 12's resistance to pressure fatigue and improves its safety and service life under repeated pressurization and depressurization cycles. Embedding the lower half of the pressure chamber 12 inside the chamber body 1, rather than having it protrude entirely from the top, reduces the overall height of the device, making its structure more compact. This helps lower the device's center of gravity, improving its stability when sinking and remaining in the mud.

[0041] Detailed operation steps: Single-time sampling: After assembling the device, tighten the counterweight 2, connect the air inlet pipe 3, steel cable 5 and cable 6, start the ground system, and check whether the readings of the air pump 4, rotating roller 10 and pressure sensor 7 are normal. Confirm that the air pump 4 is in the off or depressurized state. At this time, under the action of gravity, the piston rod 13 is in the high position, the support rod 15 is retracted, and the plug 17 has naturally sealed the slurry inlet 16 under its own gravity. Control the rotating roller 10 through the operating platform 8 to lower the entire device at a uniform speed, ensuring that the slurry inlet 16 remains closed during the sinking process, preventing mud of different depths from entering the chamber 1 during the sinking process, thereby ensuring the purity of the sample. During the descent process, the data transmitted by the pressure sensor 7 is observed and recorded in real time. Combined with the length of the steel cable 5 (which has cable markings) and the pressure value (P), a set of depth-pressure data is recorded at a preset step distance. The pressure data here is mainly used to verify and calibrate the depth. A correspondence table between the borehole depth and the sensor readings is established to provide a basic dataset for subsequent data analysis and to help determine the formation changes.

[0042] When the device descends to the first target sampling depth, the descent is stopped, the air pump 4 is started, and compressed gas is introduced into the pressure chamber 12. The gas pushes the piston 14, which drives the piston rod 13 to move downward. The support rod 15 is then opened, and the plug 17 is pulled out from the slurry inlet 16. The slurry inlet 16 is opened remotely. Under the action of hydrostatic pressure, the original mud at this depth quickly flows into the interior of the chamber 1 through the open slurry inlet 16. After maintaining air intake for a short period of time to ensure that chamber 1 is filled with mud, turn off air pump 4 and depressurize. After the air pressure is removed, the internal pressure of the device is balanced with the external pressure. The piston rod 13 returns to its original position under the action of mud pressure and gravity, which drives the support rod 15 to retract. The plug 17 reseals the slurry inlet 16, locking the sample firmly inside chamber 1. After sampling is completed, chamber 1 is resealed to ensure that the sample will not exchange with or leak from the upper layer of mud during the lifting process. After the device is fully raised to the operating platform 8, the counterweight 2 is unscrewed, and the mud sample in the chamber 1 is poured into the prepared container through the open slurry sampling port 11. The sample is then immediately labeled and the relevant performance indicators are tested.

[0043] The density of the mud can be obtained using a mud hydrometer, the viscosity of the mud can be obtained using a Marsh funnel, and the sand content of the mud can be measured using a sand content meter.

[0044] Multiple samplings below: Based on the geological survey report or construction conditions, determine the multiple target depths where sampling is required, execute all steps of single-point sampling, and obtain samples from the bottom of the borehole (the bottom samples are most susceptible to sediment contamination). Pour out the first sample on the ground and test it. Thoroughly rinse the inside of the chamber 1, check the sealing of the plug 17, and confirm that the slurry inlet 16 can be completely closed to ensure that the device is ready for the next sampling and to avoid cross-contamination of samples from different depths. The process is repeated, with the device being lowered sequentially to the second, third...Nth target depth. Samples are then collected at each depth to obtain a series of independent, unmixed, undisturbed slurry samples at different depths. The data recorded by the pressure sensor 7 during each deployment are compiled, and the measured depth of each actual sampling point is fitted with the corresponding sensor reading. By combining the continuous pressure-depth data (using interpolation or high-order curve fitting) with a limited number of discrete sampling points, the estimated values ​​of mud indicators at each point are obtained in turn, and the overall mud performance is evaluated.

[0045] Among them, by monitoring the hydrostatic pressure in real time through pressure sensor 7, the operator can accurately calculate the depth of the device. The calculation formula is: H = P / (ρ*g), where H is the depth, P is the pressure value, ρ is the density, and g is the gravitational acceleration.

[0046] If the density of the drilling mud is <1.25g / cm³ using a mud hydrometer, the viscosity of the drilling mud is ≤28s using a Marsh funnel, and the sand content of the drilling mud is ≤8% using a sand content meter, then the drilling mud in the bored pile meets the quality requirements.

[0047] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A multi-depth mud sampling device for bored piles, characterized in that: Includes a silo body (1), the lower end of which is provided with a slurry inlet (11), a counterweight (2) is detachably connected to the slurry inlet (11), the top of which is provided with an integrally formed pressure chamber (12), a piston rod (13) is slidably arranged in the pressure chamber (12), the upper end of which is fixed with a piston (14), the lower end of which extends downward out of the pressure chamber (12) and into the interior of the silo body (1), and a number of support rods (15) are provided on the outer peripheral wall of the lower end of the piston rod (13). The other end of 15) is connected to a plug (17) for sealing the slurry inlet (16). The upper side wall of the chamber (1) is provided with a slurry inlet (16) that is compatible with the plug (17). The top of the pressure chamber (12) is provided with an air inlet (121). The air inlet (121) is connected to the air pump (4) through the air inlet pipe (3). The top of the chamber (1) is also connected with a steel cable (5) and a cable (6) fixing buckle. The end of the cable (6) is electrically connected to the pressure sensor (7) installed on the top of the chamber (1).

2. The multi-depth mud sampling device for bored piles according to claim 1, characterized in that: The side wall of the silo (1) is divided into an upper side (101) and a lower side (102) from top to bottom. The upper side (101) is inclined outward, and the slurry inlet (16) is opened on the upper side (101). The lower side (102) is connected to the lower end of the upper side (101) and is inclined inward to form a closed opening that cooperates with the counterweight (2).

3. The multi-depth mud sampling device for bored piles according to claim 2, characterized in that: Several pressure sensors (7) are installed on the top surface of the chamber (1).

4. The multi-depth mud sampling device for bored piles according to claim 2, characterized in that: The inner wall of the slurry inlet (11) is provided with an internal thread; the top of the counterweight (2) is provided with a connecting section (21) that matches the closing section, the outer wall of the connecting section (21) is provided with an external thread that matches the internal thread, and the bottom surface of the counterweight (2) is an arc surface that facilitates sinking.

5. The multi-depth mud sampling device for bored piles according to claim 1 or 2, characterized in that: The upper top wall of the pressure chamber (12) is an arched structure, and its lower half extends into the interior of the chamber body (1).

6. The multi-depth mud sampling device for bored piles according to claim 1, characterized in that: The number of the support rods (15) is 4, and the silo body (1) has 4 corresponding slurry inlets (16).

7. The multi-depth mud sampling device for bored piles according to claim 1, characterized in that: The cable (6) is covered with a waterproof protective sleeve.

8. The multi-depth mud sampling device for bored piles according to claim 1, characterized in that: The air pump (4) is mounted on the operating platform (8), and the operating platform (8) is also provided with a portal frame (9). A rotating roller (10) driven by a power device is installed on the portal frame (9), and the steel cable (5) and the cable (6) are wound around the rotating roller (10).

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