Over-length pile foundation quality detection apparatus and method for deep foundation pit enclosure structure

Abstract

Disclosed is an over-length pile foundation quality detection apparatus for a deep foundation pit enclosure structure, comprising multiple acoustic measurement pipes that are vertically arranged in parallel on a rebar cage of a pile foundation, the multiple acoustic measurement pipes being oppositely arranged in pairs, and bottom ends of the acoustic measurement pipe being connected by means of a connecting support; a sound wave generator and a receiving transducer are respectively disposed in every pair of oppositely arranged acoustic measuring pipes, the sound wave generator and the receiving transducer each being connected to a sound wave detector arranged outside the pile foundation by means of cables. The present over-length pile foundation quality detection apparatus for deep foundation pit enclosure structures causes a sound wave emitter and a sound wave transducer to be always kept in the center of an acoustic measurement pipe when the acoustic measurement pipe ascends and descends, by means of matching of a limiting sliding protrusion in an acoustic measurement pipe with limiting grooves embedded in the sound wave emitter and the sound wave transducer, so that measurement accuracy is higher, and an evaluation result of pile foundation integrity is more accurate.

Description

A device and method for detecting the quality of ultra-long pile foundations of deep foundation pit retaining structures Technical Field

[0001] The present invention relates to the field of civil engineering pile foundation quality detection, and in particular to a device and method for detecting the quality of an ultra-long pile foundation of a deep foundation pit retaining structure. Background Art

[0002] Pile foundations, as a deep foundation structure, have been widely used in civil engineering. They transfer the weight and loads of the superstructure to the stable soil layer in contact with the piles, thereby significantly reducing foundation settlement and uneven building settlement. Pile foundations offer advantages such as high bearing capacity, minimal settlement, and strong seismic resistance. They are widely used in areas with complex geological conditions, soft soil, and frequent earthquakes, achieving remarkable results. Pile foundations can be categorized by their construction process as cast-in-place piles or precast piles. Cast-in-place piles are the most widely used, particularly in bridges, highways, railways, and high-rise buildings. However, during the construction process, pile foundations are susceptible to defects such as broken piles, necking, shrinking, segregation, mud inclusions, sediment, and voids, due to factors such as construction techniques, personnel handling, external conditions, and material quality. These defects pose potential risks to buildings and significantly impact their quality. If the defects cannot support the weight of the superstructure, they can cause building collapse, resulting in severe losses. Therefore, pile foundation testing is extremely important. Only by promptly detecting defective piles and implementing effective preventive measures can building quality be significantly improved. Currently available methods for testing pile foundation quality include static load testing, core drilling, low-strain testing, high-strain testing, self-balancing testing, and ultrasonic transmission testing. The ultrasonic transmission method for testing concrete quality relies on pre-embedding several ultrasonic testing tubes within the pile, which serve as channels for ultrasonic receiving and transmitting transducers. During testing, a transmitting probe (for emitting ultrasonic waves) is placed in one tube, and a receiving probe (for receiving ultrasonic waves) is placed in the other tube. The two probes are simultaneously raised from the bottom to the top, and the instrument records the acoustic characteristics of the ultrasonic waves propagating within the concrete test surface formed by the two tubes. The arrival time, amplitude, frequency variation, and degree of waveform distortion are analyzed and processed to determine the concrete quality, the nature, size, and spatial location of any defects, and the concrete homogeneity.

[0003] However, the existing sonic transmission method presents several challenges. For example, pre-embedded sonic tubes must be aligned parallel to each other, otherwise the accuracy of the final test results will be affected. Furthermore, some existing methods for reinforcing sonic tubes involve placing brackets between them to ensure their stability. However, since the propagation speed of sound waves in concrete differs from that in the reinforcement brackets, this can lead to inaccurate results, further compromising the assessment of pile integrity.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a device and method for detecting the quality of super-long pile foundations of deep foundation pit retaining structures, so as to solve the problems raised in the above-mentioned background technology and improve the accuracy of pile foundation quality detection.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a device for detecting the quality of an extra-long pile foundation of a deep foundation pit retaining structure, comprising a plurality of mutually parallel acoustic detection pipes vertically arranged on a steel cage of the pile foundation, wherein the plurality of acoustic detection pipes are arranged opposite to each other in pairs and connected at their bottom ends by a connecting bracket, wherein a sound wave generator and a receiving transducer are respectively arranged in each two opposing acoustic detection pipes, and the sound wave generator and the receiving transducer are respectively connected to an acoustic wave detector arranged outside the pile foundation by cables.

[0008] Furthermore, each of the acoustic detection pipes is connected end to end in sequence by multiple sections of acoustic detection pipes, and the connections between adjacent acoustic detection pipes are fixed by wrapping with sleeves.

[0009] Furthermore, the connecting bracket is provided with a plurality of sealing covers which are sleeved and matched with the end portions of the acoustic detection pipes.

[0010] Furthermore, each of the sound wave generators and each of the receiving transducers is respectively provided with a nesting that slides with the inner wall of the acoustic detection pipeline.

[0011] Furthermore, two limiting sliding protrusions are symmetrically provided on the inner wall of each of the acoustic detection pipes, and two limiting grooves respectively matched with the two limiting sliding protrusions are symmetrically provided on the outer wall of the nested pipes.

[0012] In addition, the present invention also discloses a method for detecting the quality of an extra-long pile foundation of a deep foundation pit retaining structure, which uses the above-mentioned detection device and includes the following steps:

[0013] S1. Before construction, the pile foundation construction site should be cleaned, leveled and compacted, the construction site should be arranged, and the storage area for the mud pool, steel cage and construction machinery should be scientifically and detailedly planned;

[0014] S2. Use a total station to stake out the pile position, then bury the steel casing. The casing strength should meet the rigidity and strength requirements. Fill and tamp the outside of the casing with clay.

[0015] S3. Use a drilling rig to drill. When the drilling depth reaches the designed hole depth, check the hole position, hole diameter, hole depth and inclination to ensure that they meet the specification requirements, and then clean the hole;

[0016] S4. Prepare a steel cage and place four acoustic detection pipes in the steel cage, with the distance between each of the acoustic detection pipes being equal;

[0017] S5. Lower the steel cage into the pre-dug pile foundation. When placing the steel cage, be sure to keep it in a vertical position to avoid tilting.

[0018] S6. Pour concrete and wait for the concrete to solidify.

[0019] S7. After the concrete solidifies for a few days, set up an acoustic wave detector outside the pile foundation, place the acoustic wave transmitter and transducer in the pre-installed acoustic testing pipe, and start testing; determine the integrity of the pile body based on the received acoustic wave parameters.

[0020] Furthermore, in step S4, when placing the acoustic detection pipe, it is required to be set next to the vertical steel bar corresponding to the steel cage and tangent to the vertical steel bar, and then stirrups are used to clamp the acoustic detection pipe and the adjacent steel bars. Stirrups are used to tie the acoustic detection pipe every 1 meter along the length of the acoustic detection pipe.

[0021] Furthermore, in step S4, after the acoustic detection tubes are installed, the bottom openings of each acoustic detection tube are sealed using multiple sealing caps connected to the bracket. The steel cage is then lowered into the pre-excavated pile foundation, ensuring that the cage remains vertical and prevents it from tilting. The acoustic detection tubes are then filled with clean water, and the top openings of each acoustic detection tube are sealed using the sealing caps connected to the bracket.

[0022] Furthermore, in step S4, the number of acoustic detection pipes to be installed is determined according to the pile diameter. When the pile diameter is less than or equal to 800 mm, the number of acoustic detection pipes cannot be less than two; when the pile diameter is between 800 mm and 1600 mm, the number of acoustic detection pipes cannot be less than three; when the pile diameter is greater than 1600 mm, the number of acoustic detection pipes cannot be less than four.

[0023] Furthermore, in step S7, before starting the measurement, the connection brackets on the top of the plurality of acoustic testing pipes need to be removed.

[0024] Compared with the prior art, the present invention has the following beneficial technical effects:

[0025] The ultra-long pile foundation quality detection device for a deep foundation pit retaining structure of the present invention has a limiting sliding protrusion inside the acoustic detection pipe that fits with the nested limiting grooves on the acoustic wave transmitter and the acoustic wave transducer, so that the acoustic wave transmitter and the acoustic wave transducer always remain in the center position of the acoustic detection pipe when the acoustic detection pipe is raised or lowered, thereby making the measurement accuracy higher and the judgment of the integrity result of the pile foundation more accurate.

[0026] In addition, in the quality inspection method of the ultra-long pile foundation of the deep foundation pit retaining structure of the present invention, the acoustic detection pipe is placed between two adjacent vertical steel bars, tangent to the two steel bars, and the bottom and top of the four acoustic detection pipes are sealed and connected with the sealing cover of the cross bracket. This can ensure that the four acoustic detection pipes remain parallel, so that the acoustic wave parameters obtained when using acoustic wave measurement are more accurate, and the judgment of the integrity of the pile body is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below with reference to the accompanying drawings.

[0028] FIG1 is a schematic diagram of the overall structure of the present invention;

[0029] FIG2 is a perspective view of the acoustic detection pipeline;

[0030] FIG3 is a perspective view of the sleeve;

[0031] Fig. 4 is a nested perspective view;

[0032] FIG5 is a cross-sectional perspective view of the acoustic detection pipeline;

[0033] FIG6 is a cross-sectional perspective view of the transmitter in the acoustic detection tube;

[0034] FIG7 is a perspective view of a cross bracket;

[0035] FIG8 is a perspective view of a cross bracket connected to an acoustic detection tube;

[0036] Explanation of the accompanying drawings: 1. Acoustic wave detector; 2. Cable; 3. Acoustic detection pipeline; 301. Limiting sliding protrusion; 4. Nesting; 401. Limiting groove; 5. Acoustic wave transmitter; 6. Sleeve; 7. Acoustic wave transducer; 8. Foundation pile; 9. Cross bracket; 901. Sealing cover. DETAILED DESCRIPTION

[0037] As shown in Figures 1 to 8, a device for detecting the quality of ultra-long pile foundations of a deep foundation pit retaining structure includes a plurality of parallel acoustic detection pipes 3 vertically arranged on the steel cage of the pile foundation 8. In this embodiment, the number of the acoustic detection pipes 3 is four, and each of the acoustic detection pipes 3 can be connected end to end in sequence by multiple sections of acoustic detection pipes, and the connection between adjacent acoustic detection pipes is wrapped and fixed by a sleeve 6 as shown in Figure 3.

[0038] The four acoustic detection pipes 3 are arranged opposite to each other in pairs and their bottom ends are connected by a connecting bracket, as shown in Figures 7 and 8. The connecting bracket in this embodiment is specifically set as a cross bracket 9, and the cross bracket 9 is provided with four sealing covers 901 that are sleeved with the ends of each of the acoustic detection pipes 3.

[0039] Each of the two opposing acoustic testing pipes 3 is provided with an acoustic wave generator 5 and a receiving transducer 7 , respectively. The acoustic wave generator 5 and the receiving transducer 7 are connected to an acoustic wave detector 1 provided outside the pile foundation 8 via a cable 2 .

[0040] In addition, as shown in Figures 4-6, each of the acoustic wave generators 5 and each of the receiving transducers 7 is provided with a nesting element 4 that slidably engages with the inner wall of the acoustic detection pipe 3. Two limiting protrusions 301 are symmetrically provided on the inner wall of each acoustic detection pipe 3, and two limiting grooves 401 are symmetrically provided on the outer wall of the nesting element 4, each of which is adapted to the two limiting protrusions 301.

[0041] In addition, the present invention also discloses a method for detecting the quality of an extra-long pile foundation of a deep foundation pit retaining structure, which uses the above-mentioned detection device and includes the following steps:

[0042] S1. Before construction, the pile foundation construction site should be cleaned, leveled and compacted, the construction site should be arranged, and the storage area of ​​the mud pool, steel cage and construction machinery should be scientifically and detailedly planned.

[0043] S2. Use a total station to stake out the pile position, then bury the steel casing. The casing strength should meet the rigidity and strength requirements. Fill and tamp the outside of the casing with clay, and the top of the casing should be 0.5m above the ground.

[0044] S3. Use a drilling rig to drill. When the drilling depth reaches the designed hole depth, check the hole position, hole diameter, hole depth and inclination to ensure that they meet the specification requirements, and then clean the hole;

[0045] S4. Make a steel cage and place four acoustic detection pipes in the steel cage, with the distance between each two of the acoustic detection pipes being equal.

[0046] When placing the acoustic detection pipe, it is required to be set next to the vertical steel bar corresponding to the steel cage and tangent to the vertical steel bar, and then use stirrups to clamp the acoustic detection pipe and the adjacent steel bars. Along the length of the acoustic detection pipe, stirrups are used to tie it every 1 meter.

[0047] In this step, the number of acoustic detection pipes installed is determined according to the pile diameter. When the pile diameter is less than or equal to 800 mm, the number of acoustic detection pipes cannot be less than two; when the pile diameter is between 800 mm and 1600 mm, the number of acoustic detection pipes cannot be less than three; when the pile diameter is greater than 1600 mm, the number of acoustic detection pipes cannot be less than four; when the pile diameter is greater than 2500 mm, the number of acoustic detection pipes should be appropriately increased in addition to the four acoustic detection pipes.

[0048] S5. Lower the steel cage into the pre-excavated pile foundation. When placing the steel cage, be sure to keep it upright to prevent it from tilting. Specifically: After the acoustic detection pipes are installed, seal the bottom openings of each acoustic detection pipe using the multiple sealing caps on the cross bracket. Then, lower the steel cage into the pre-excavated pile foundation. When placing the steel cage, be sure to keep it upright to prevent it from tilting. Then, fill each acoustic detection pipe with clean water, and seal the top opening of each acoustic detection pipe with the sealing caps on the cross bracket.

[0049] S6. Pour concrete and wait for the concrete to solidify.

[0050] S7. After the concrete solidifies for several days, which is 28 days in this embodiment, the connecting brackets on the top of the multiple acoustic detection pipes need to be removed before starting the measurement.

[0051] An acoustic wave detector is set up outside the pile foundation, and then the acoustic wave transmitter 5, the acoustic wave transducer 7 and the acoustic wave detector 1 are debugged. The acoustic wave transmitter and the transducer are placed in the pre-installed acoustic detection pipe. Specifically: the hoop 44 of Figure 4 is placed on the upper part of the acoustic wave transmitter 5 and the acoustic wave transducer 7. There are two limiting grooves 401 on the hoop 4 that are symmetrical about the center of the circle. The outer peripheral wall of the hoop 4 of Figure 4 slides with the inner peripheral wall of the acoustic detection pipe, and the limiting groove of the hoop of Figure 4 fits with the limiting protrusion 301 of the acoustic detection pipe 3, so that the acoustic wave transmitter 5 and the acoustic wave transducer 7 can move vertically in the acoustic detection pipe 3 along the axial direction of the acoustic detection pipe 3. The sectional stereoscopic view of the transmitter in the acoustic detection pipe is shown in Figure 6, and the same applies to the transducer. The acoustic wave transmitter 5 and the acoustic wave detector 1 are connected via a cable 2, and the acoustic wave transducer 7 and the acoustic wave detector 1 are also connected via a corresponding cable 2. The acoustic wave transmitter 5 and the acoustic wave transducer 7 are placed into the acoustic detection tube 3 in the above manner. The height of the transmitter 5 and the transducer 7 is controlled by stretching the cable 2 to perform concrete detection between the transmitter 5 and the transducer 7. After the detection begins, the integrity of the pile body is determined based on the received acoustic wave parameters.

[0052] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A device for detecting the quality of super-long pile foundations of deep foundation pit retaining structures, characterized in that: It comprises a plurality of mutually parallel acoustic detection pipes vertically arranged on the steel cage of the pile foundation, wherein the plurality of acoustic detection pipes are arranged opposite to each other in pairs and the bottom ends are connected by a connecting bracket, and a sound wave generator and a receiving transducer are respectively arranged in each two opposite acoustic detection pipes, and the sound wave generator and the receiving transducer are respectively connected to the sound wave detector arranged outside the pile foundation by cables.

2. The ultra-long pile foundation quality detection device for deep foundation pit retaining structure according to claim 1 is characterized by: Each of the acoustic detection pipelines is connected end to end in sequence by multiple sections of acoustic detection pipes, and the connection between adjacent acoustic detection pipes is wrapped and fixed by a sleeve.

3. The ultra-long pile foundation quality detection device for deep foundation pit retaining structure according to claim 1 is characterized by: The connecting bracket is provided with a plurality of sealing covers which are sleeved and matched with the ends of the acoustic detection pipes.

4. The ultra-long pile foundation quality detection device for deep foundation pit retaining structure according to claim 1 is characterized by: Each of the sound wave generators and each of the receiving transducers is respectively provided with a nesting member that is slidably matched with the inner wall of the acoustic detection pipeline.

5. The ultra-long pile foundation quality detection device for deep foundation pit retaining structure according to claim 4 is characterized in that: Two limiting sliding protrusions are symmetrically arranged on the inner wall of each of the acoustic detection pipes, and two limiting grooves respectively matched with the two limiting sliding protrusions are symmetrically arranged on the nested outer wall.

6. The method for detecting the quality of super-long pile foundation of a deep foundation pit retaining structure according to any one of claims 1 to 5, characterized in that: The steps include: S1. Before construction, the pile foundation construction site should be cleaned, leveled and compacted, the construction site should be arranged, and scientific and detailed planning should be made for the storage area of ​​the mud pool, steel cage and construction machinery; S2. Use a total station to stake out the pile position, then bury the steel casing. The casing strength should meet the rigidity and strength requirements. Fill and tamp the outside of the casing with clay. S3. Use a drilling rig to drill holes. When the drilling depth reaches the designed hole depth, check the hole position, hole diameter, and hole depth. Check the depth and inclination to ensure that the specifications are met, and then clean the hole; S4, making a steel cage, placing four acoustic detection pipes in the steel cage, and the distances between each of the acoustic detection pipes are equal; S5. Place the steel cage into the pre-dug pile foundation. When placing the steel cage, make sure to keep it vertical to avoid tilting. S6. Pour concrete and wait for the concrete to solidify. S7. After the concrete solidifies for a few days, set up an acoustic wave detector outside the pile foundation, place the acoustic wave transmitter and transducer in the pre-installed acoustic detection pipe, and start the detection; determine the integrity of the pile body based on the received acoustic wave parameters.

7. The device and method for detecting the quality of super-long pile foundation of deep foundation pit retaining structure according to claim 6, characterized in that: In step S4, when placing the acoustic detection pipe, it is required to be set beside the vertical steel bar corresponding to the steel cage and tangent to the vertical steel bar, and then stirrups are used to clamp the acoustic detection pipe and the adjacent steel bars. Stirrups are used to tie the acoustic detection pipe every 1 meter along the length of the acoustic detection pipe.

8. The device and method for detecting the quality of super-long pile foundation of deep pit foundation retaining structure according to claim 6, characterized in that: In step S5, after the acoustic detection pipes are placed, the bottom pipe openings of each acoustic detection pipe are sealed by multiple sealing covers connected to the bracket. Then the steel cage is lowered into the pre-dug pile foundation. When placing the steel cage, it is important to keep the steel cage in a vertical state to avoid tilting the steel cage. Then, each acoustic detection pipe is filled with clean water, and the top pipe openings of each acoustic detection pipe are sealed with sealing covers connected to the bracket.

9. The device and method for detecting the quality of super-long pile foundation of deep pit foundation retaining structure according to claim 6, characterized in that: In step S4, the number of acoustic detection pipes to be installed is determined according to the pile diameter. When the pile diameter is less than or equal to 800 mm, the number of acoustic detection pipes cannot be less than two; When the pile diameter is between 800 mm and 1600 mm, the number of acoustic detection pipes shall not be less than three; when the pile diameter is greater than 1600 mm, the number of acoustic detection pipes shall not be less than four.

10. The device and method for detecting the quality of super-long pile foundation of deep pit foundation retaining structure according to claim 6, characterized in that: In step S7, before starting the measurement, the connection brackets on the tops of the plurality of acoustic testing pipes need to be removed.

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