A pile foundation detection method based on ultrasonic wave

Abstract

The present invention relates to the technical field of pile foundation detection, and in particular to an ultrasonic-based pile foundation detection method, comprising: after a pile body is prepared, it is left to stand for a first preset time, ultrasonic detection is performed, and whether the preparation of the pile body meets a preset standard is determined according to an energy attenuation characterization value; when it is determined that the preparation of the pile body does not meet the preset standard according to the energy attenuation characterization value, a secondary determination is made according to a waveform characterization value whether the preparation of the pile body meets the preset standard, or the reason why the preparation of the pile body does not meet the preset standard is determined according to an amplitude recovery rate; when it is determined that the preparation of the pile body meets the preset standard according to the energy attenuation characterization value, a pedestal is cast; when it is determined that the preparation of the pedestal does not meet the preset standard according to the density characterization value, the concrete pouring rate is reduced or the pouring is stopped and an early warning is issued, thereby improving the accuracy of ultrasonic detection.

Description

Technical Field

[0001] The present invention relates to the technical field of pile foundation detection, and in particular to an ultrasonic-based pile foundation detection method. Background Art

[0002] A pile foundation is a deep foundation consisting of piles and pile caps connected to the tops of the piles. Its core function is to transfer the building load to the harder bearing layer underground through the piles, thereby increasing the bearing capacity and reducing the risk of settlement.

[0003] Ultrasonic testing transmits high-frequency elastic pulse waves through the pile body. The receiving end records the changes in wave velocity, amplitude and waveform characteristics. When there are defects in the concrete, such as holes or honeycomb structures, the ultrasonic waves will be reflected, scattered or attenuated. By analyzing the signal anomalies, the integrity of the pile body can be determined.

[0004] However, the dynamic changes in the physical properties of concrete during the solidification process have not been fully considered. If testing is carried out too early before the final setting state is reached, misjudgment may occur due to the instability of the concrete material. At the same time, conventional testing cannot distinguish between false defects caused by insufficient solidification time and real structural defects, resulting in a lack of targeted follow-up treatment measures. In addition, the density monitoring of the foundation pouring stage mostly relies on manual experience or a single parameter threshold, and the construction parameters cannot be dynamically adjusted, resulting in low detection efficiency.

[0005] Chinese patent application publication number CN119355132A discloses a bridge pile foundation defect detection system based on ultrasonic technology. The system comprises a control terminal for controlling and managing the system's overall operational processes and performing real-time data monitoring; a multi-channel, high-frequency ultrasonic detection module for transmitting ultrasonic signals through a multi-channel, high-frequency probe array and receiving reflected signals from within the bridge pile foundation to generate raw detection data; and a parallel computing and 3D imaging module for performing parallel computing on the received ultrasonic signal data to generate a three-dimensional structural image of the bridge pile foundation. By combining the multi-channel, high-frequency ultrasonic detection module with phased array technology and multi-reflection wave processing techniques, high-precision detection of the internal structure of bridge pile foundations is achieved.

[0006] It can be seen that the above technical solution does not take into account the influence of the static time of the pile and the final setting time of the concrete on the ultrasonic detection, which leads to misjudgment of the ultrasonic detection; at the same time, the graded early warning mechanism based on the density characterization value is not introduced in the foundation construction stage, which cannot prevent the formation of through-hole defects and realize the self-reliance of the construction process, thus leading to the problem of low accuracy of ultrasonic detection. Summary of the Invention

[0007] To this end, the present invention provides an ultrasonic-based pile foundation detection method to overcome the problem that the prior art does not consider the influence of the static time of the pile body and the final setting time of concrete on the ultrasonic detection, resulting in misjudgment of the ultrasonic detection; at the same time, a graded early warning mechanism based on the density characterization value is not introduced during the foundation construction stage, which cannot prevent the formation of through-hole defects and realize the self-reliance of the construction process, thereby leading to the problem of low ultrasonic detection accuracy.

[0008] To achieve the above object, the present invention provides an ultrasonic-based pile foundation detection method, comprising:

[0009] After the pile body is prepared, it is left to stand for a first preset time, and ultrasonic testing is performed to obtain a number of amplitudes of the pile body provided with a number of detection bands, and to obtain an energy attenuation characterization value;

[0010] When it is determined that the preparation of the pile body does not meet the preset standard according to the energy attenuation characterization value, the peak value of the waveform of the first ultrasonic wave is collected and the waveform characterization value is obtained, and the pile body is left to stand for a second preset time to obtain the amplitude of the pile body and obtain the amplitude recovery rate;

[0011] Secondarily determining whether the preparation of the pile body meets the preset standard based on the waveform characterization value, or determining the reason why the preparation of the pile body does not meet the preset standard based on the amplitude recovery rate, the reason including the presence of holes in the pile body or deviation of the energy attenuation characterization value;

[0012] When the pile preparation is judged to meet the preset standards according to the energy attenuation characterization value, the foundation cap is poured;

[0013] The sound velocity of each detection point of the pedestal is obtained to determine the density characterization value of the pedestal. When it is determined based on the density characterization value that the preparation of the pedestal does not meet the preset standard, the concrete pouring rate is reduced or the pouring is stopped and an early warning is issued.

[0014] Furthermore, it is determined whether the preparation of the pile body meets the preset standards based on the energy attenuation characterization value, wherein:

[0015] If the energy attenuation characteristic value is less than the first preset energy attenuation characteristic value, it is determined that the preparation of the pile body meets the preset standard and the foundation pouring is carried out;

[0016] If the energy attenuation characterization value is greater than or equal to the first preset energy attenuation characterization value and less than the second preset energy attenuation characterization value, it is determined that the preparation of the pile body has a tendency not to meet the preset standard, and a second determination is made based on the waveform characterization value whether the preparation of the pile body meets the preset standard;

[0017] If the energy attenuation characterization value is greater than or equal to the second preset energy attenuation characterization value, it is determined that the preparation of the pile body does not meet the preset standard, and the reason why the preparation of the pile body does not meet the preset standard is determined based on the amplitude recovery rate.

[0018] Furthermore, the energy attenuation characterization value is a standard deviation of the amplitude corresponding to a number of test points, wherein the test points are all located on a number of detection zones uniformly distributed along the pile body in radial directions.

[0019] Furthermore, the reason why the preparation of the pile body does not meet the preset standard is determined based on the amplitude recovery rate of the pile body, wherein:

[0020] If the amplitude recovery rate is less than the preset amplitude recovery rate, it is determined that the reason why the preparation of the pile body does not meet the preset standard is that holes appear in the pile body, and the vibration frequency of the pile body is increased according to the difference between the amplitude recovery rate and the preset amplitude recovery rate;

[0021] If the amplitude recovery rate is greater than or equal to the preset amplitude recovery rate, it is determined that the preparation of the pile body does not meet the preset standard because the first preset time is less than the final setting time of the concrete of the pile body, resulting in a deviation in the energy attenuation characterization value obtained by ultrasonic testing.

[0022] Furthermore, several frequency increasing methods are provided for increasing the vibration frequency of the pile body, and each frequency increasing method has a different increase amplitude on the vibration frequency of the pile body.

[0023] Furthermore, the process of obtaining the amplitude recovery rate includes:

[0024] After the pile body has been left to stand for a first preset time, a plurality of detection zones are evenly divided along the radial direction of the pile body, each detection zone being provided with a plurality of test points;

[0025] Using the double-sided measurement method, the transmitting transducer and the receiving transducer are respectively fixed at the test points of the adjacent detection zone, the first wave amplitude of each test point is collected, and the arithmetic mean of the first wave amplitude of the test points of the pile body is obtained and recorded as the initial test amplitude;

[0026] Then, after the pile body is left to stand for a second preset time, the amplitude measurement is repeated at the same test point, and the arithmetic mean of the first wave amplitudes of the test points after the second preset time is obtained, which is recorded as the retest amplitude;

[0027] The amplitude recovery rate is the ratio of the re-test amplitude to the initial test amplitude.

[0028] Furthermore, a secondary determination is made as to whether the preparation of the pile body meets the preset standard based on the waveform characterization value of the pile body, wherein:

[0029] If the waveform characterization value is less than the preset waveform characterization value, it is determined that the preparation of the pile body does not meet the preset standard;

[0030] If the waveform characterization value is greater than or equal to the preset waveform characterization value, the pile preparation is determined to meet the preset standard and the foundation casting is carried out;

[0031] The waveform characterization value is the ratio between the number of ultrasonic waveform peak values that are greater than or equal to the preset peak value and the total number.

[0032] Furthermore, whether the preparation of the foundation meets the preset standard is determined based on the density characterization value of the foundation, wherein:

[0033] If the density characterization value is less than the first preset density characterization value, it is determined that the preparation of the foundation meets the preset standard;

[0034] If the density characterization value is greater than or equal to a first preset density characterization value and less than a second preset density characterization value, it is determined that the preparation of the pile cap does not meet the preset standard and the pouring rate of the concrete of the pile cap is reduced according to the difference between the density characterization value and the first preset density characterization value;

[0035] If the density characterization value is greater than or equal to the second preset density characterization value, it is determined that the preparation of the foundation does not meet the preset standard, and the reason why the preparation of the foundation does not meet the preset standard is determined to be that the foundation has a penetration defect, and the preparation is terminated and an early warning is issued;

[0036] The through-hole defects include one or more of the following: the presence of cavities in the foundation, or the presence of mud inclusions in the foundation, or the presence of a honeycomb structure in the foundation.

[0037] Furthermore, the reduction range of the pouring rate of the concrete of the foundation is positively correlated with the density characterization difference, wherein the density characterization difference is the difference between the density characterization value and the first preset density characterization value.

[0038] Furthermore, the process of obtaining the density characterization value of the foundation pile includes:

[0039] During the pouring process of the cap, a number of ultrasonic detection tubes are evenly arranged;

[0040] A multi-channel ultrasonic detector is used to synchronously excite the transmitting transducers of each detection tube, record the first wave sound velocity value of each detection tube, and calculate the arithmetic average of the first wave sound velocity values of each detection tube;

[0041] The standard deviation of the first wave sound velocity value of the foundation is obtained according to the arithmetic mean of the first wave sound velocity values of each detection tube, and is recorded as the density characterization value of the foundation.

[0042] Compared with the prior art, the beneficial effect of the present invention lies in that, by setting the correlation detection between the static time of the pile body and the final setting time of the concrete, combined with the dual test of the energy attenuation characterization value and the amplitude recovery rate, the present invention can effectively distinguish between the false amplitude attenuation caused by the failure of the concrete to final set and the real pile foundation structure defects, thereby avoiding misjudgment of detection; a graded early warning mechanism based on the standard deviation of the speed of sound is introduced during the foundation pile construction stage, and the formation of through-hole defects such as honeycomb structures or voids is prevented by dynamically adjusting the pouring rate or suspending construction, thereby realizing intelligent control of the quality of pile foundation and foundation pile preparation, realizing adaptive adjustment of the construction process and precise positioning of defects, thereby improving detection accuracy.

[0043] Furthermore, the present invention uses the amplitude standard deviation as the quantitative basis for the energy attenuation characterization value to achieve an objective evaluation of pile body uniformity defects, reflect the degree of discreteness of the amplitude in different detection bands, and accurately locate local defects. The standard deviation indicator is more sensitive to abnormal amplitude values, thereby avoiding the uniformity defects being masked by the overall arithmetic mean.

[0044] Furthermore, the present invention ensures that the ultrasonic detection is synchronized with the final setting state of concrete by setting the interval judgment of the static detection and energy attenuation characterization value for a first preset time, avoiding false defect judgments caused by insufficient static time, thereby improving the detection accuracy of the pile foundation.

[0045] Furthermore, the present invention provides several frequency increasing modes for increasing the vibration frequency of the pile body, and each frequency increasing mode increases the vibration frequency of the pile body by a different amount, thereby achieving precise control of the increase amplitude of the vibration frequency of the pile body.

[0046] Furthermore, the present invention determines that the local density is insufficient when the density characterization value is between the first and second preset values, and optimizes the fluidity of the concrete by reducing the pouring rate; when the density characterization value is greater than or equal to the second preset value, it determines that there is a penetration defect, immediately suspends construction and issues a warning to avoid the expansion of the defect and reduce the cost of rework in the later stage, thereby achieving graded warning.

[0047] Furthermore, the present invention can sensitively reflect the abnormal uniformity inside the foundation through the density characterization value calculated based on the standard deviation of the speed of sound, thereby achieving accurate positioning of the cause of the defect. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a flow chart of an ultrasonic pile foundation detection method according to an embodiment of the present invention;

[0049] Figure 2 This is a flow chart of an embodiment of the present invention for determining whether the preparation of a pile body meets a preset standard based on an energy attenuation characterization value;

[0050] Figure 3 A flow chart of determining why the preparation of a pile body does not meet a preset standard according to an embodiment of the present invention;

[0051] Figure 4 This is a flow chart for determining whether the preparation of the support meets preset standards according to an embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0053] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0054] It should be pointed out that the data in this embodiment are all obtained by comprehensive analysis and evaluation of the historical test data of the present invention in the three months before this test and the corresponding historical test results. Those skilled in the art can understand that the method of determining the above-mentioned single parameter of the method of the present invention can be to select the value with the highest proportion as the preset standard parameter according to the data distribution, use weighted summation to use the obtained value as the preset standard parameter, substitute each historical data into a specific formula and use the value obtained by the formula as the preset standard parameter or other selection methods, as long as the method of the present invention can clearly define the different specific situations in the single determination process through the obtained value.

[0055] See also Figure 1 、 Figure 2 、 Figure 3 as well as Figure 4 As shown, it is a flow chart of the ultrasonic-based pile foundation detection method according to an embodiment of the present invention; a flow chart of determining whether the preparation of the pile body meets the preset standard according to the energy attenuation characterization value according to an embodiment of the present invention; a flow chart of determining the reason why the preparation of the pile body does not meet the preset standard according to an embodiment of the present invention; a flow chart of determining whether the preparation of the base meets the preset standard according to an embodiment of the present invention.

[0056] An embodiment of the present invention provides an ultrasonic-based pile foundation detection method, which includes:

[0057] Step S1: After the pile body is prepared, it is left to stand for a first preset time of 8 hours, and ultrasonic testing is performed to obtain a number of amplitudes of the pile body provided with a number of detection bands, and to obtain an energy attenuation characterization value;

[0058] Step S2: when it is determined that the preparation of the pile body does not meet the preset standard based on the energy attenuation characterization value, the peak value of the waveform of the first ultrasonic wave is collected to obtain the waveform characterization value, and after the pile body is left to stand for a second preset time of 11 hours, the amplitudes of several detection bands of the pile body uniformly distributed along the pile body are obtained to obtain the amplitude recovery rate;

[0059] Step S3, when it is determined based on the energy attenuation characterization value that the preparation of the pile body does not meet the preset standard, a secondary determination is made based on the waveform characterization value whether the preparation of the pile body meets the preset standard, or the reason why the preparation of the pile body does not meet the preset standard is determined based on the amplitude recovery rate, the reason including the presence of holes in the pile body or the deviation of the energy attenuation characterization value;

[0060] Step S4, when it is determined that the preparation of the pile body meets the preset standard according to the energy attenuation characterization value, the foundation pile is poured;

[0061] Step S5, obtaining the sound velocity of each detection point of the pedestal, and obtaining the density characterization value of the pedestal. When it is determined based on the density characterization value that the preparation of the pedestal does not meet the preset standard, the concrete pouring rate is reduced or the pouring is stopped and an early warning is issued.

[0062] In this embodiment, the value range of the first preset time length is (5h, 10h), and the value range of the second preset time length is (6h, 12h). Preferably, the first preset time length is selected as 8h, and the second preset time length is selected as 11h.

[0063] Specifically, the energy attenuation characterization value is used to determine whether the pile preparation meets the preset standards, wherein:

[0064] If the energy attenuation characteristic value is less than the first preset energy attenuation characteristic value of 0.8dB, it is determined that the preparation of the pile body meets the preset standard and the foundation pouring is carried out;

[0065] If the energy attenuation characterization value is greater than or equal to the first preset energy attenuation characterization value and less than 1.2 dB of the second preset energy attenuation characterization value, it is determined that the preparation of the pile body has a tendency not to meet the preset standard, and a second determination is made based on the waveform characterization value whether the preparation of the pile body meets the preset standard;

[0066] If the energy attenuation characterization value is greater than or equal to the second preset energy attenuation characterization value, it is determined that the preparation of the pile body does not meet the preset standard, and the reason why the preparation of the pile body does not meet the preset standard is determined based on the amplitude recovery rate.

[0067] Specifically, the energy attenuation characterization value is the standard deviation of the amplitude corresponding to a number of test points, wherein the test points are all located on a number of detection zones uniformly distributed along the pile body in radial directions.

[0068] In this embodiment, the value range of the first preset energy attenuation characterization value is (0.5dB, 0.9dB), and the value range of the second preset energy attenuation characterization value is (1.0dB, 1.3dB). Preferably, the first preset energy attenuation characterization value is selected as 0.8dB, and the second preset energy attenuation characterization value is selected as 1.2dB.

[0069] Specifically, by calculating the standard deviation of the amplitude of the radially uniformly distributed detection points on the pile body as the energy attenuation representation value, the uniformity of the concrete distribution of the pile body can be objectively reflected, avoiding misjudgment caused by abnormalities at a single detection point. By comparing the energy attenuation representation value with the preset representation value, a hierarchical control mechanism is implemented, thereby improving the test accuracy.

[0070] Specifically, the reason why the preparation of the pile body does not meet the preset standard is determined based on the amplitude recovery rate of the pile body, wherein:

[0071] If the amplitude recovery rate is less than a preset amplitude recovery rate of 1.15, it is determined that the reason why the preparation of the pile body does not meet the preset standard is that the pile body has holes, and the vibration frequency of the pile body is increased according to the difference between the amplitude recovery rate and the preset amplitude recovery rate;

[0072] If the amplitude recovery rate is greater than or equal to the preset amplitude recovery rate, it is determined that the preparation of the pile body does not meet the preset standard because the first preset time is less than the final setting time of the concrete of the pile body, resulting in a deviation in the energy attenuation characterization value obtained by ultrasonic testing. In fact, the preparation of the pile body meets the preset standard.

[0073] In this embodiment, the amplitude recovery rate obtained by testing a large number of qualified pile foundations is obtained by taking the arithmetic average, but the above value is not limited to this, and those skilled in the art can also adjust the value according to actual needs.

[0074] Specifically, there are several frequency increasing methods for increasing the vibration frequency of the pile body, among which:

[0075] If the amplitude recovery rate difference is less than the first preset amplitude recovery rate difference of 0.35, the vibration frequency of the pile body is increased to a corresponding value using the first frequency adjustment coefficient of 1.02;

[0076] If the amplitude recovery rate difference is greater than or equal to the first preset amplitude recovery rate difference and less than the second preset amplitude recovery rate difference of 0.55, the vibration frequency of the pile body is increased to the corresponding value using the second frequency adjustment coefficient of 1.04;

[0077] If the amplitude recovery rate difference is greater than or equal to the second preset amplitude recovery rate difference, the vibration frequency of the pile body is increased to a corresponding value using a third frequency adjustment coefficient of 1.06;

[0078] The amplitude recovery rate difference is the difference between the amplitude recovery rate and the preset amplitude recovery rate.

[0079] Specifically, the process of obtaining the amplitude recovery rate includes:

[0080] After the pile body has been left to stand for a first preset time, a plurality of detection zones are evenly divided along the radial direction of the pile body, each detection zone being provided with a plurality of test points;

[0081] Using the double-sided measurement method, the transmitting transducer and the receiving transducer are respectively fixed at the test points on the two sides of the pile body corresponding to the detection zone. The first wave amplitude of each test point is collected by a digital ultrasonic detector, and the arithmetic mean of the first wave amplitude of the test points of the pile body is obtained and recorded as the initial detection amplitude.

[0082] Then, after the pile body is left to stand for a second preset time, the amplitude measurement is repeated at the same test point, and the arithmetic mean of the first wave amplitudes of the test points after the second preset time is obtained, which is recorded as the retest amplitude;

[0083] The amplitude recovery rate is the ratio of the re-test amplitude to the initial test amplitude.

[0084] The first wave refers to the earliest identifiable waveform captured by the transmitting transducer and the receiving transducer when the ultrasonic wave propagates in the concrete medium.

[0085] The first wave amplitude refers to the maximum vertical distance between the first wave peak and the waveform reference line when the ultrasonic wave propagates in the concrete medium. In this embodiment, a digital ultrasonic detector is used to obtain the amplitude.

[0086] Specifically, a secondary determination is made as to whether the preparation of the pile body meets the preset standard based on the waveform characterization value of the pile body, wherein:

[0087] If the waveform characterization value is less than the preset waveform characterization value of 0.75, it is determined that the preparation of the pile body does not meet the preset standard;

[0088] If the waveform characterization value is greater than or equal to the preset waveform characterization value, the pile preparation is determined to meet the preset standard and the foundation casting is carried out;

[0089] The waveform characterization value is the ratio of the number of ultrasonic waveform peak values greater than or equal to a preset peak value of 60 mV to the total number.

[0090] Specifically, the peak value reflects the ultrasonic energy transmission efficiency and is positively correlated with the uniformity of concrete.

[0091] Specifically, whether the preparation of the foundation meets the preset standard is determined according to the density characterization value of the foundation, wherein:

[0092] If the density characterization value is less than the first preset density characterization value of 0.12 km / s, it is determined that the preparation of the foundation meets the preset standard;

[0093] If the density characterization value is greater than or equal to the first preset density characterization value and less than the second preset density characterization value of 0.35 km / s, it is determined that the preparation of the pile cap does not meet the preset standard and the pouring rate of the concrete of the pile cap is reduced according to the difference between the density characterization value and the first preset density characterization value;

[0094] If the density characterization value is greater than or equal to the second preset density characterization value, it is determined that the preparation of the foundation does not meet the preset standard, and the reason why the preparation of the foundation does not meet the preset standard is determined to be that the foundation has a penetration defect, and the preparation is terminated and an early warning is issued;

[0095] The through-hole defects include one or more of the following: the presence of cavities in the foundation, or the presence of mud inclusions in the foundation, or the presence of a honeycomb structure in the foundation.

[0096] In this embodiment, the first preset density characterization value is 0.12 km / s, and the second preset density characterization value is 0.35 km / s, but the above values are not limited thereto. Those skilled in the art can also adjust the values according to actual needs.

[0097] Specifically, the reduction in the pouring rate of the concrete of the pedestal is positively correlated with the density characterization difference, wherein the positive correlation can be, for example, a linear positive correlation or a nonlinear positive correlation, and the linear slope of the linear positive correlation is not specifically limited. It can be understood that the greater the density characterization difference, the greater the reduction in the pouring rate of the concrete of the pedestal; the density characterization difference is the difference between the density characterization value and the first preset density characterization value.

[0098] Specifically, the process of obtaining the density characterization value of the foundation pile includes:

[0099] During the pouring process of the cap, a number of ultrasonic detection tubes are evenly arranged;

[0100] A multi-channel ultrasonic detector is used to synchronously excite the transmitting transducers of each detection tube, record the first wave sound velocity value of each detection tube, and calculate the arithmetic average of the first wave sound velocity values of each detection tube;

[0101] The standard deviation of the first wave sound velocity value of the foundation is obtained according to the arithmetic mean of the first wave sound velocity values of each detection tube, and is recorded as the density characterization value of the foundation.

[0102] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

[0103] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A pile foundation detection method based on ultrasonic wave, characterized in that: include: After the pile body is prepared, it is left to stand for a first preset time, and ultrasonic testing is performed to obtain a number of amplitudes of the pile body provided with a number of detection bands, and to obtain an energy attenuation characterization value; When it is determined that the preparation of the pile body does not meet the preset standard according to the energy attenuation characterization value, the peak value of the waveform of the first ultrasonic wave is collected and the waveform characterization value is obtained, and the pile body is left to stand for a second preset time to obtain the amplitude of the pile body and obtain the amplitude recovery rate; Secondarily determining whether the preparation of the pile body meets the preset standard based on the waveform characterization value, or determining the reason why the preparation of the pile body does not meet the preset standard based on the amplitude recovery rate, the reason including the presence of holes in the pile body or deviation of the energy attenuation characterization value; When the pile preparation is judged to meet the preset standards according to the energy attenuation characterization value, the foundation cap is poured; Obtain the sound velocity at each detection point of the cap and calculate the density characterization value of the cap. If the cap preparation is judged not to meet the preset standard based on the density characterization value, the concrete pouring rate is reduced or the pouring is stopped and an early warning is issued; The energy attenuation characterization value is used to determine whether the pile preparation meets the preset standards, where: If the energy attenuation characteristic value is less than the first preset energy attenuation characteristic value, it is determined that the preparation of the pile body meets the preset standard and the foundation pouring is carried out; If the energy attenuation characterization value is greater than or equal to the first preset energy attenuation characterization value and less than the second preset energy attenuation characterization value, it is determined that the preparation of the pile body has a tendency not to meet the preset standard, and a second determination is made based on the waveform characterization value whether the preparation of the pile body meets the preset standard; If the energy attenuation characteristic value is greater than or equal to the second preset energy attenuation characteristic value, it is determined that the preparation of the pile body does not meet the preset standard, and the reason why the preparation of the pile body does not meet the preset standard is determined based on the amplitude recovery rate; Secondary determination is made based on the waveform characterization value of the pile body whether the preparation of the pile body meets the preset standard, wherein: If the waveform characterization value is less than the preset waveform characterization value, it is determined that the preparation of the pile body does not meet the preset standard; If the waveform characterization value is greater than or equal to the preset waveform characterization value, the pile preparation is determined to meet the preset standard and the foundation casting is carried out; The waveform characterization value is the ratio between the number of ultrasonic waveform peak values that are greater than or equal to the preset peak value and the total number.

2. The ultrasonic pile foundation detection method according to claim 1, characterized in that: The energy attenuation characterization value is the standard deviation of the amplitude corresponding to a number of test points, wherein the test points are all located on a number of detection zones uniformly distributed along the pile body in radial directions.

3. The ultrasonic pile foundation detection method according to claim 2, characterized in that: The reason why the preparation of the pile body does not meet the preset standard is determined based on the amplitude recovery rate of the pile body, wherein: If the amplitude recovery rate is less than the preset amplitude recovery rate, it is determined that the reason why the preparation of the pile body does not meet the preset standard is that holes appear in the pile body, and the vibration frequency of the pile body is increased according to the difference between the amplitude recovery rate and the preset amplitude recovery rate; If the amplitude recovery rate is greater than or equal to the preset amplitude recovery rate, it is determined that the preparation of the pile body does not meet the preset standard because the first preset time is less than the final setting time of the concrete of the pile body, resulting in a deviation in the energy attenuation characterization value obtained by ultrasonic testing.

4. The ultrasonic pile foundation detection method according to claim 3, characterized in that: In order to increase the vibration frequency of the pile body, several frequency increasing methods are provided, and each frequency increasing method increases the vibration frequency of the pile body by a different amplitude.

5. The ultrasonic pile foundation detection method according to claim 4, characterized in that: The process of obtaining the amplitude recovery rate includes: After the pile body has been left to stand for a first preset time, a plurality of detection zones are evenly divided along the radial direction of the pile body, each detection zone being provided with a plurality of test points; Using the double-sided measurement method, the transmitting transducer and the receiving transducer are respectively fixed at the test points of the adjacent detection zone, the first wave amplitude of each test point is collected, and the arithmetic mean of the first wave amplitude of the test points of the pile body is obtained and recorded as the initial test amplitude; Then, after the pile body is left to stand for a second preset time, the amplitude measurement is repeated at the same test point, and the arithmetic mean of the first wave amplitudes of the test points after the second preset time is obtained, which is recorded as the retest amplitude; The amplitude recovery rate is the ratio of the re-test amplitude to the initial test amplitude.

6. The ultrasonic-based pile foundation detection method according to claim 5, characterized in that: Determine whether the preparation of the foundation meets the preset standard according to the density characterization value of the foundation, wherein: If the density characterization value is less than the first preset density characterization value, it is determined that the preparation of the foundation meets the preset standard; If the density characterization value is greater than or equal to a first preset density characterization value and less than a second preset density characterization value, it is determined that the preparation of the pile cap does not meet the preset standard and the pouring rate of the concrete of the pile cap is reduced according to the difference between the density characterization value and the first preset density characterization value; If the density characterization value is greater than or equal to the second preset density characterization value, it is determined that the preparation of the foundation does not meet the preset standard, and the reason why the preparation of the foundation does not meet the preset standard is determined to be that the foundation has a penetration defect, and the preparation is terminated and an early warning is issued; The through-hole defects include one or more of the following: the presence of cavities in the foundation, the presence of mud inclusions in the foundation, and the presence of a honeycomb structure in the foundation.

7. The ultrasonic pile foundation detection method according to claim 6, characterized in that: The reduction range of the pouring rate of the concrete of the foundation is positively correlated with the density characterization difference, wherein the density characterization difference is the difference between the density characterization value and the first preset density characterization value.

8. The ultrasonic-based pile foundation detection method according to claim 7, characterized in that: The process of obtaining the density characterization value of the foundation pile includes: During the pouring process of the cap, a number of ultrasonic detection tubes are evenly arranged; A multi-channel ultrasonic detector is used to synchronously excite the transmitting transducers of each detection tube, record the first wave sound velocity value of each detection tube, and calculate the arithmetic average of the first wave sound velocity values of each detection tube; The standard deviation of the first wave sound velocity value of the foundation is obtained according to the arithmetic mean of the first wave sound velocity values of each detection tube, and is recorded as the density characterization value of the foundation.

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