CN115421182B - Pile-in-rock-solution detection method and system based on array transducer - Google Patents
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Abstract
The invention belongs to the technical field of geotechnical engineering investigation, and particularly provides a pile-in karst detection method and system based on an array transducer, wherein the method comprises the following steps: the array transducer is put in the pile bottom position; controlling array elements on the array transducer to emit and receive ultrasonic signals; and recording amplitude values at all times in the ultrasonic wave propagation process, and giving the amplitude values to imaging points to obtain an imaging model. The scheme has low requirements on the construction environment of the pile bottom, the interference of ultrasonic signals is small, the signal to noise ratio is high, the data acquisition efficiency is improved, and the accurate detection of the pile bottom and the pile Zhou Yanrong is realized.
Description
Technical Field
The invention relates to the technical field of geotechnical engineering investigation, in particular to a pile-in-rock-solution detection method and system based on an array transducer.
Background
The pile foundation has the characteristics of adaptability to various engineering geological conditions, various engineering requirements, higher bearing capacity and strong load transmission capacity, and can effectively reduce uneven settlement of a building (construction) and reduce adverse effects of karst on a foundation to a certain extent. Therefore, pile foundations are widely used in track engineering construction of karst areas. However, karst cave development is greatly different in size, the shape is changed in a lot, the section shape is extremely irregular, and great difficulty is brought to pile foundation design and construction in karst areas. Under the condition that the karst cave development of a pile position is not ascertained, the bearing capacity of a pile foundation is difficult to accurately design, and meanwhile, when a cast-in-place pile is constructed in a karst developed stratum, accidents such as pile hole slurry leakage, pile hole collapse, pile hole inclination, ground collapse, concrete sudden leakage and the like are likely to occur in the construction process. The accidents often have the characteristics of burst property, unpredictability and high processing difficulty, and many engineering projects are forced to be stopped due to improper accident processing and untimely processing, so that the engineering cost is increased, and the accidents become geological problems of controlling the construction period, controlling the engineering cost, threatening the construction safety and affecting the engineering quality.
The pile bottom karst detection target is mainly the karst hidden in the bedrock, the size and the space development range are extremely complex, and when the pile bottom karst is detected by using drilling, the karst beside the drilling is very easy to miss. From the aspect of plane distribution, the space range is difficult to be ascertained by using point substitution surfaces, and the adverse conditions of pile foundation half rock embedding and the like in the actual construction process are likely to be caused. The exploration method selects a pile to be porous, and the cost is very high in terms of cost and construction period. Even so, it is difficult to clearly grasp the specific development condition of karst on the whole pile position, and the bridge is possibly unstable and damaged when the adverse condition is serious, and the unexposed bridge exists in a hidden danger mode and is gradually exposed in the operation period.
Pile bottom karst detection is a investigation technology for detecting karst distribution characteristics of a pile bottom bedrock bearing stratum in a certain range by adopting a direct (drilling method) or an indirect (geophysical prospecting method).
The pile bottom karst detection method in the exploration stage mainly comprises an advanced drilling method, a pipe wave detection method, a drilling radar method, a drilling multi-frequency sound wave detection method and a cross-hole elastic wave method. Single advanced drilling is extremely easy to miss karst, and the construction period is greatly influenced by increasing drilling. The pipe wave detection method can detect the vertical distribution range of karst in the rock mass within the drilling radius of 1m, has higher vertical precision, but the detection result has no directivity, can not indicate the abnormal spatial distribution of karst and crushing around the hole, and is easy to be influenced by stratum interfaces, aperture changes, non-karst cave wave impedance interfaces at liquid level and the like. The principle of the drilling radar and the multi-frequency sound wave detection method is similar to that of the tube wave detection, and the problem of detection directivity is not solved. The cross-hole elastic wave CT is used for reconstructing the internal structure of the geologic body through tomography by observing the changes of travel time, energy (amplitude), waveform and the like when the seismic wave passes through the geologic body, and has higher detection precision. However, in karst areas, the detectors are not effectively coupled when the well fluid in the hole leaks, and therefore cannot be implemented.
The construction stage investigation method mainly comprises a geological radar method and an acoustic wave reflection method. The geological radar method is used for collecting geological radar data by arranging an annular or cross section at the pile bottom, but is limited by the detection area of a field, radar ultrasonic signals are interfered by side walls, the detection depth is limited, and the method is only suitable for manual hole digging pile detection. The acoustic wave reflection method ((a pile bottom karst cave sonar detection device and method CN 104101896A)) utilizes slurry coupling excitation and ultrasonic wave reception to detect the karst development condition of the pile bottom by arranging a transducer at the pile bottom, the device has limited acquisition data, fixed offset distance and incapability of acquiring high-density reflected wave data with multiple angles and multiple offset distances, and the device is mainly used for identifying the karst of the pile bottom by identifying reflected waveform change and waveform time-frequency characteristic analysis, can not determine the height or range of the karst, and is easy to detect by hole wall wave reflection interference and the like.
The prior pile bottom karst detection can not meet the engineering investigation requirement, and the prior pile bottom karst detection is difficult to implement and needs drilling and matching; the requirement on the pile bottom environment is high; the acquired data are less and cannot be imaged with high quality; the detection result has no directivity, and the specific condition of karst development of the pile bottom can not be determined.
Search for prior art findings: patent 1, "a three-dimensional detection method, a device, equipment and a storage medium CN 112904348A", uses a plurality of transducers to form a one-dimensional linear arrangement, and performs three-dimensional detection on the pile bottom in a one-shot multi-shot collection and rotation collection mode. Patent 2, "a three-dimensional detection method, apparatus, device and storage medium CN112817039 a" uses a plurality of transducers to form a two-dimensional sensor array, and uses different combinations of dot lines and planes to perform three-dimensional detection. Patent 3 pile bottom karst detection method, device and system, electronic equipment and storage medium CN112630764A uses emission delay to control each sensor of a transducer array to carry out wave beam phase control so as to carry out pile bottom three-dimensional detection. In the technology described in the above patent, the requirement on the consistency of each transducer unit is very high mainly for a transducer array formed by combining a plurality of transducers, in addition, in patent 3, phased detection is introduced, only two directions are scanned in phase, the whole pile bottom detection range cannot be covered, in addition, the number of transducer units required by phased array detection is large, each channel needs to be controlled separately, and the circuit design difficulty is high and the cost is high.
In summary, the existing pile bottom karst detection method mainly has the following technical problems: (1) difficult detection implementation requires drilling cooperation; the requirement on the pile bottom environment is high; (2) less acquired data is not amenable to high quality imaging; (3) The detection result has no directivity, and (4) the specific condition of karst development of the pile bottom can not be determined. And the following problems also mainly exist in the prior art: the number of transducer units is large, and the consistency requirement is high; (2) incomplete coverage angle of the phased scanning pile bottom; (3) The single transducer has small emission energy, poor beam focusing and weak penetration capability; and (4) the detection near-field blind area is large.
Disclosure of Invention
Aiming at the problems that the implementation of the existing pile bottom karst detection method in the prior art is difficult, the drilling and matching are needed; the method has the technical problems of high requirements on pile bottom environment, more transducer units and high consistency requirements.
The invention provides an in-pile karst detection method based on an array transducer, which comprises the following steps of:
s1, putting an array transducer into a pile;
S2, controlling array elements on the array transducer to transmit and receive ultrasonic signals;
And S3, recording amplitude values at all times in the ultrasonic wave propagation process and giving the amplitude values to imaging points to obtain an imaging model of pile bottom karst or pile periphery karst.
Preferably, the releasing mode in the step S1 includes sinking or suspending:
When the sinking mode is used, the transducer is sunk into the pile bottom by dead weight, and after the transducer is attached to the pile bottom surface, the array elements on the array transducer are controlled to transmit and receive ultrasonic signals;
When the suspended mode is used, the array transducer is lifted to a preset height from the bottom surface of the pile, and the array elements on the array transducer are controlled to transmit and receive ultrasonic signals so as to detect karst at the shallow part of the pile bottom.
Preferably, when the suspended mode is used, the array transducer can be laterally placed close to the pile wall, and the array elements on the array transducer are controlled to transmit and receive ultrasonic signals so as to detect the pile Zhou Yanrong.
Preferably, the S2 specifically includes a point scan mode, a line scan mode, or a plane scan mode; wherein the method comprises the steps of
Point scan mode: each array element of the array transducer area array transmits ultrasonic signals in sequence, and other array elements or all array elements synchronously receive the signals until a full matrix scanning data set is acquired;
Line scan mode: each row or each column of array elements of the array transducer sequentially transmits ultrasonic signals, and other array elements or all array elements synchronously receive signals until full linear array scanning data are acquired;
Surface scanning mode: and transmitting signals by the whole array surface of the array transducer, and synchronously receiving signals by all array elements until the surface array scanning data are acquired.
Preferably, the S2 specifically includes:
The method comprises the steps of controlling all array elements to synchronously transmit signals or respectively and independently controlling the excitation delay time of each array element, collecting data by adopting a phase control scanning mode, and specifically adopting the phase control scanning mode to comprise the following steps:
the rotation scanning mode comprises the steps of controlling an inclination angle alpha to scan along the fixed direction of an azimuth angle beta, scanning the inclination angle alpha according to a preset angle range, and changing the azimuth angle beta after the scanning along the fixed direction is completed until the scanning along the real 360-degree direction is completed; or (b)
The grid scanning mode scans according to rows or columns, firstly sets the inclination angle of the scanning rows or columns, and then scans according to the wave velocity deflection angle of the rows or columns.
Preferably, the S2 further includes: transmitting pulse ultrasonic signals by using array elements on edges or corners of the array transducer, taking ultrasonic signals received by receiving array elements which are in the same row or column as the transmitting array elements and far away from the transmitting array elements, respectively taking the difference between the time for receiving the ultrasonic signals by two adjacent receiving array elements to obtain delay time, and combining the array element spacing to calculate the initial propagation speed;
all the preliminary propagation speeds are averaged to obtain the propagation speed of the ultrasonic waves in the bedrock.
Preferably, the calculating process of the imaging point amplitude in S3 specifically includes:
Equally dividing an imaging area into image points P at equal intervals, transmitting ultrasonic signals by using transmitting array elements S with I rows and j columns in a point acquisition data set R (I, j, m and n), and receiving ultrasonic signals received by receiving array elements G with m rows and n columns, wherein the imaging amplitude I p of the imaging points P is as follows:
Wherein i, j, m, n is a natural number, t spg is t s+tg, B is a diffusion calibration coefficient, D s is a calibration coefficient of an array transducer pointing to a transmitting element, D g is a calibration coefficient of an array transducer pointing to a receiving element, B s is a diffusion calibration coefficient of an array transducer pointing to a transmitting element, and B g is a diffusion calibration coefficient of an array transducer pointing to a receiving element, and the calculation formula is as follows:
wherein a is the side length of an array transducer array element, D is the directivity calibration coefficient of the array transducer, θ is the angle from an imaging point to a transmitting array element or a receiving array element, and D is the distance from the imaging point to the transmitting array element or the receiving array element; or (b)
When phase control scanning imaging is adopted, the delay sequence of each array element in the process of scanning and collecting data of each beam angle is that the delay sequence is subtracted from the ultrasonic signals received by each array element, then the ultrasonic signals of the beam angles are obtained by accumulating and summing at each moment, the ultrasonic signals are subjected to time deep conversion according to speed, and the ultrasonic signals obtained by rotating and scanning are obtained;
and the pile bottom karst imaging is obtained by carrying out combined imaging on the data acquired at a plurality of positions of the pile bottom, or the pile periphery karst imaging is obtained by carrying out imaging on the data acquired at the pile periphery.
Preferably, the calculating the amplitude of the imaging point in S3 further includes calculating time:
When in point scanning imaging, calculating the distance d s from the transmitting array element S to the imaging point P, and calculating the distance d g from the imaging point P to the receiving array element G, wherein the corresponding propagation time is t s＝ds/v,tg＝dg/v respectively; v is the propagation speed of the ultrasonic signal in the bedrock;
when line scanning or surface scanning imaging is performed, calculating the distance R ij from P to each emission array element S ij for each imaging point P, and then Ts ij＝Rij/V+tij, wherein T ij is the delay time of each array element, calculating the time TS ij from the imaging point P to the emission array S, and taking the minimum value as the propagation time T s from the imaging point P; wherein T g is the distance from the imaging point P to the sensor G, and the distance from the imaging point P to the receiving sensor G is R g, to obtain T g＝Rg/V.
Preferably, the method for calculating the minimum time T s from the transmitting array element S to the imaging point P can obtain accurate wave field propagation time in isotropic homogeneous medium, and for more complex medium, the method can also be obtained by solving a three-dimensional equation, namely another method for calculating T s is as follows:
The three-dimensional equation of the journey is Wherein T represents the first arrival time of the sound wave, V (x,y,z) is the speed value of the rectangular coordinate (x, y, z) of the three-dimensional space, x, y, z are the directions of the rectangular coordinate system of the three-dimensional space respectively, and the three-dimensional arrival time of the surface excitation form is obtained by setting the equation of the micro-path of each excitation array element solving time to the space, so as to obtain the time T s from the sound wave signal emitted by the surface array sensor to the imaging point.
The invention also provides a pile bottom karst detection system based on the array transducer, which is used for realizing an in-pile karst detection method based on the array transducer, and comprises the following steps:
The data acquisition module is used for throwing the array transducer into the pile and controlling the array element on the array transducer to transmit and receive ultrasonic signals;
and the imaging module records the amplitude values at all times in the ultrasonic wave propagation process and gives the amplitude values to imaging points to obtain an imaging model.
The beneficial effects are that: the invention provides a pile-in karst detection method and system based on an array transducer, wherein the method comprises the following steps: s1, throwing the array transducer to the middle position of the pile bottom; s2, controlling array elements on the array transducer to emit ultrasonic signals, and collecting data in a phase control scanning mode; and S3, recording amplitude values at all times in the ultrasonic wave propagation process and giving the amplitude values to imaging points to obtain an imaging model. The high-frequency sound wave reflection principle is used for detecting the pile bottom, and the pile bottom slurry coupling is utilized, so that the requirement on the pile bottom construction environment is low. The array transducer is used, each array element has good consistency, concentrated wave beams, high transverse resolution, strong energy, slow attenuation, small interference on ultrasonic signals and high signal to noise ratio. The beam is flexibly controlled, the position of the device is not required to be changed, the detection speed is high, and the data acquisition efficiency is improved. The scanning detection in water and the scanning detection at the bottom of the pile can reduce the shallow detection blind area and realize the accurate detection of the shallow and deep karst at the bottom of the pile.
Drawings
FIG. 1 is a flow chart of a method for detecting in-pile karst based on an array transducer;
FIG. 2 is a schematic diagram of delayed emission of ultrasonic signals according to the present invention;
FIG. 3 is a schematic diagram of a rotational scan provided by the present invention;
FIG. 4 is a diagram of a grid scan according to the present invention;
fig. 5 is a three-dimensional imaging diagram of phased scanning of an array transducer provided by the invention.
Detailed Description
The following describes in further detail the embodiments of the present invention with reference to the drawings and examples. The following examples are illustrative of the invention and are not intended to limit the scope of the invention.
As shown in fig. 1 to 5, the method for detecting the in-pile karst based on the array transducer provided by the invention comprises the following steps:
s1, throwing the array transducer to a pile bottom position; the transducer is generally arranged in the middle of the pile bottom, and the signal emission direction is downward, namely the array transducer is horizontally arranged;
S2, controlling array elements on the array transducer to emit ultrasonic signals, and collecting data in a phase control scanning mode;
and S4, recording amplitude values at all times in the ultrasonic wave propagation process and giving the amplitude values to imaging points to obtain an imaging model.
The whole process is approximately as follows: array transducer arrangement-point emission data acquisition-phase control data acquisition-water surface emission data acquisition-data synthesis.
The method uses the high-frequency sound wave reflection principle to detect the pile bottom, and utilizes the coupling of pile bottom slurry, thereby having low requirements on the construction environment of the pile bottom. The array type transducer is used, each array element has good consistency, the beams are concentrated, the transverse resolution is high, the energy is strong, the attenuation is slow, the interference of ultrasonic signals is small, and the signal to noise ratio is high. The beam is flexibly controlled, the position of the device is not required to be changed, the detection speed is high, and the data acquisition efficiency is improved. The scanning detection in water and the scanning detection at the bottom of the pile can reduce the shallow detection blind area and realize the accurate detection of the shallow and deep karst at the bottom of the pile.
In the preferred proposal, the array transducer is lifted, in the lifting process, all array elements simultaneously transmit and receive ultrasonic signals, the pile bottom or the pile bottom is collected by a phase control scanning mode,
And lifting the array transducer, wherein the transmitting direction of the array transducer faces the inner wall of the pile in the lifting process, and all array elements simultaneously transmit and receive ultrasonic signals and acquire data of the inner wall of clump of pile in a phase control scanning mode. Typically near the side of the pile, and the direction of signal emission is horizontal, i.e. the array transducer is placed vertically or at an inclination.
The specific implementation process is as follows:
First step, array transducer arrangement: and putting the array transducer in the middle of the pile bottom.
The main frequency of the transmitted ultrasonic signals is 50KHz, each piezoelectric wafer in the array transducer has good consistency, the array transducer array elements have larger bandwidth, the m rows and n columns of array transducer array elements have larger bandwidth, the distance between the array center points is half of the wavelength of the transmitted ultrasonic signals, and each array element uses an independent excitation and receiving circuit module. The array element spacing dx is 0.05m.
And step two, data transmission and collection.
And controlling an i row and j column single (or whole row/column/whole area array) array element S ij on the array transducer to transmit ultrasonic signals, wherein all array elements simultaneously and independently receive ultrasonic signals R ij,Rij to form an ultrasonic signal set received by m rows and n columns of array elements, the ultrasonic signal set comprises m multiplied by n ultrasonic signal sequences, and transmitting each array element and receiving all array elements are sequentially completed to obtain all ultrasonic signal sets R.
Specifically, a single excitation array element on a corner of the array transducer is controlled to emit a pulse ultrasonic signal, and other array elements receive the ultrasonic signal. The excitation array element is a seismic source, and in the process of transmitting the sound wave from the excitation array element to each receiving seismic source, the sound wave transmission path is as follows: sensor-mud-bedrock-mud-sensor. An excitation array element emits sound waves, namely pulse ultrasonic signals are emitted through the excitation point, and the rest array elements receive the ultrasonic signals.
And taking ultrasonic signals received by the array elements far away from the excited array element, performing cross-correlation between ultrasonic signals received by any two receiving array elements, and when the time of the ultrasonic signals received by the two receiving array elements is closest, indicating that the correlation coefficient is the largest, at the moment, indicating that the two receiving array elements are adjacent array elements, namely, the two receiving array elements are closest, namely, the two receiving array elements are adjacent array elements. The time difference between the two corresponding array elements for receiving the ultrasonic signals is the delay time t, and the distance between the adjacent array elements is dx, so that the propagation speed v=dx/t of the ultrasonic waves between the adjacent array elements can be calculated. The method is adopted to obtain the initial propagation velocity V of the ultrasonic signals among all the adjacent array elements, and then the propagation velocity V obtained by calculating all the adjacent ultrasonic signals is averaged to obtain the propagation velocity V of the ultrasonic signals in the bedrock.
Or the given velocity V 0,V0 is the propagation velocity of the assumed pulse ultrasonic signal in the bedrock, which is then corrected: and respectively calculating the distance L from the excitation point to each receiving array element and the propagation time, wherein t=L/V 0, and superposing records at different t moments in each array element record to obtain the amplitude A 0. And calculating V i＝V0 + dv according to the speed increment dv to obtain a corresponding amplitude A i. And calculating to obtain V i corresponding to the maximum value of A i, namely the propagation speed V in the bedrock.
Thirdly, pile bottom phase control collection.
The two-dimensional wave beam phase control scanning mode is used for collecting data, and each array element synchronously transmits and receives ultrasonic signals. In the phase control process, each array element is independently controlled, the same excitation ultrasonic signal is used for excitation, and different excitation delays are used for controlling the wave speed for scanning when each array element is excited.
The transmitted ultrasonic signals may be pulsed ultrasonic signals, chirped ultrasonic signals, and parametric ultrasonic signals.
The scanning mode can adopt a rotary scanning mode, namely, the scanning is performed by controlling the inclination angle alpha along the fixed direction of the azimuth angle beta, the inclination angle alpha is scanned according to a certain angle range (for example + -45 DEG), and the azimuth angle beta is changed after the scanning according to the fixed direction is completed until the scanning in the true 360 DEG direction is completed. In the phase control scanning process, the delay time of each array element is calculated as follows: the time delay of the array elements according to the ith row and the jth column of each channel is t ij, and the method comprises the following steps:
Where p ij is the distance from the ith row and j column array elements to the center of the array,
Furthermore, the scanning mode can also adopt a grid scanning mode, wherein the scanning is performed according to rows or columns by controlling the excitation delay time of each array element, the inclination angle beta of a scanning row (column) is given first, and then the scanning is performed according to the modified wave speed deflection angle alpha. Alpha and beta are within a range of angles, for example + -45 deg..
In the phase control scanning process, the delay time of each array element is calculated as follows: the time delay of the array elements according to the ith row and the jth column of each channel is t ij, and the method comprises the following steps:
Wherein,
Fourthly, in-water phase control collection:
after pile bottom data testing is completed, the array transducer is lifted, in the lifting process, all array elements transmit and receive ultrasonic signals at the same time, received pile bottom reflected ultrasonic waves are judged, the distance between the array transducer and the pile bottom is calculated in real time according to the propagation speed of the ultrasonic waves in water, lifting is stopped when the distance reaches a certain height (for example, 1 meter), data are collected according to a water bottom transmitting data rotating phase control scanning mode, and the phase control angle is smaller than a first critical angle of a water-rock interface.
Fifth step, data synthesis:
The data synthesis can be aimed at point acquisition data processing and can also be aimed at area array acquisition data processing.
Point-to-point acquisition data processing
Equally dividing an imaging area into image points P at equal intervals, transmitting ij array elements S with R (i, j, m, n) in a point acquisition data set, receiving ultrasonic signals by mn array elements G, and calculating distances d s and d g from the transmitting array elements S to the imaging point P and from the imaging point P to the receiving array elements G, wherein the corresponding propagation time is t s＝ds/v,tg＝dg/v. The imaging amplitude Ip of the imaging point P is
Wherein t spg is t s+tg, B is a diffusion calibration coefficient, D s is a calibration coefficient of an array transducer pointing to a transmitting array element, D g is a calibration coefficient of an array transducer pointing to a receiving array element, B s is a diffusion calibration coefficient of an array transducer pointing to a transmitting array element, and B g is a diffusion calibration coefficient of an array transducer pointing to a receiving array element, and the calculation formula is as follows:
Wherein a is the side length of the array transducer array element, θ is the angle from the imaging point to the transmitting array element or the receiving array element, and d is the distance from the imaging point to the transmitting array element or the receiving array element.
Processing the phase control scanning acquisition data and processing the opposite acquisition data:
The delay sequence of each array element in the process of scanning and collecting data of each beam angle is t ij, the delay sequence t ij is subtracted from the ultrasonic signals received by each array element, and then the ultrasonic signals of the beam angles alpha and beta are obtained by accumulating and summing at each moment. Performing time-depth conversion on each ultrasonic signal according to the speed, and obtaining ultrasonic signals by rotary scanning, wherein coordinates corresponding to amplitude values of the ultrasonic signals at the time t are
The ultrasonic signal obtained by grid scanning is characterized in that the coordinates corresponding to the amplitude value of the ultrasonic signal at the moment t are
Furthermore, for more accurate imaging of pile bottom structures, area array ultrasonic signal data imaging can also be used. The distance of the emission sensor array S to the imaging point P and the imaging point P to each array element G ij is calculated, and the corresponding propagation time T s、Tg is calculated at the velocity V obtained in the previous step.
Further, the method for calculating the propagation time T s is as follows: for each imaging point P, calculate the distance R ij of P to each occurrence element S ij, ts ij＝Rij/V+tij, where t ij is the delay time of each element. The minimum value of the time Ts ij from the imaging point P to the transmitting array S is calculated as the point T s.Tg, which is relatively simple, and the distance R g from the imaging point P to the receiving sensor G is calculated to obtain T g＝Rg/V.
Furthermore, the method for calculating the minimum time Ts from the transmitting array element S to the imaging point P can obtain accurate wave field propagation time in isotropic uniform media, and can also be obtained by solving a program function equation for more complex media. That is, another Ts calculation method is as follows:
The three-dimensional equation of the journey is Wherein T represents the first arrival time of the sound wave, V (x,y,z) is the speed value of the three-dimensional space coordinates (x, y, z), x, y, z are the directions of the rectangular coordinate system, and the three-dimensional arrival time of the surface excitation form is obtained by setting the micro-equation of each excitation source solving time to the space, so as to obtain the time T s from the sound wave signal emitted by the area array sensor to the imaging point.
Further, the time calculation method can also be used for the imaging processing of the linear array scan data.
And cutting off the direct wave ultrasonic signals with fixed length from the ultrasonic signals received by each array element, and giving the ultrasonic signal amplitude at the moment T s+Tg to the imaging point P. The above process is repeated, and the ultrasonic signals of all the transmission/reception pairs are calculated as an imaging value cumulative sum at the imaging point P. And calculating imaging values of all imaging points P to obtain the three-dimensional imaging model under the observation system.
The embodiment of the invention also provides a pile bottom karst detection system based on the phased array transducer, which is used for realizing the pile inner karst detection method based on the phased array transducer, and comprises the following steps:
the data acquisition module is used for throwing the array transducer to the middle position of the pile bottom, controlling the array element on the array transducer to emit ultrasonic signals and acquiring data in a phase control scanning mode;
and the imaging module records the amplitude values at all times in the ultrasonic wave propagation process and gives the amplitude values to imaging points to obtain an imaging model.
The high-frequency sound wave reflection principle is used for detecting the pile bottom, the pile bottom slurry coupling is utilized, the requirement on the pile bottom construction environment is low, and no additional drilling is needed. And the emission delay of each array element of the phased array is controlled, and data of different angles are acquired, so that the radial detection range of the pile bottom is expanded. And processing the reflection data acquired in different transmitting directions by using a planar array imaging technology, and carrying out high-precision three-dimensional imaging on pile bottom karst. In addition, the defect that blind areas exist in pile bottom detection can be effectively overcome by adopting a method combining underwater detection and pile bottom detection.
In the foregoing embodiments, the descriptions of the embodiments are focused on, and for those portions of one embodiment that are not described in detail, reference may be made to the related descriptions of other embodiments.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (7)
1. An array transducer-based in-pile karst detection method is characterized by comprising the following steps of:
s1, putting an array transducer into a pile;
S2, controlling array elements on the array transducer to transmit and receive ultrasonic signals;
s3, recording amplitude values at all times in the ultrasonic wave propagation process and giving the amplitude values to imaging points to obtain an imaging model of pile bottom karst or pile periphery karst;
the calculating process of the imaging point amplitude in the step S3 specifically comprises the following steps:
Equally dividing an imaging area into image points P at equal intervals, transmitting ultrasonic signals by using transmitting array elements S with I rows and j columns in a point acquisition data set R (I, j, m and n), and receiving ultrasonic signals received by receiving array elements G with m rows and n columns, wherein the imaging amplitude I p of the imaging points P is as follows:
;
Wherein i, j, m, n is a natural number, t spg is t s+tg, B is a diffusion calibration coefficient, D s is a calibration coefficient of an array transducer pointing to a transmitting element, D g is a calibration coefficient of an array transducer pointing to a receiving element, B s is a diffusion calibration coefficient of an array transducer pointing to a transmitting element, and B g is a diffusion calibration coefficient of an array transducer pointing to a receiving element, and the calculation formula is as follows:
；
Wherein a is the side length of an array transducer array element, D is the directivity calibration coefficient of the array transducer, θ is the angle from an imaging point to a transmitting array element or a receiving array element, and D is the distance from the imaging point to the transmitting array element or the receiving array element;
When phase control scanning imaging is adopted, the delay sequence of each array element in the process of scanning and collecting data of each beam angle is that the delay sequence is subtracted from the ultrasonic signals received by each array element, then the ultrasonic signals of the beam angles are obtained by accumulating and summing at each moment, the ultrasonic signals are subjected to time deep conversion according to speed, and the ultrasonic signals obtained by rotating and scanning are obtained; the method comprises the steps of carrying out combined imaging on data acquired from a plurality of positions of a pile bottom to obtain pile bottom karst imaging, or carrying out imaging on data acquired from the periphery of a pile to obtain pile periphery karst imaging;
the calculating process of the imaging point amplitude in S3 further includes calculating time:
when in point scanning imaging, calculating the distance d s from the transmitting array element S to the imaging point P, and calculating the distance d g from the imaging point P to the receiving array element G, wherein the corresponding propagation time is t s = ds/v,tg=dg/v respectively; v is the propagation speed of the ultrasonic signal in the bedrock;
When line scanning or surface scanning imaging is performed, calculating the distance R ij from P to each emission array element S ij for each imaging point P, and then Ts ij = Rij/V+tij, wherein T ij is the delay time of each array element, calculating the time TS ij from the imaging point P to the emission array S, and taking the minimum value as the propagation time T s from the imaging point P; wherein T g is the distance from the imaging point P to the sensor G, and the distance from the imaging point P to the receiving sensor G is R g, so as to obtain T g=Rg/V;
The method for calculating the minimum time T s from the transmitting array element S to the imaging point P can obtain accurate wave field propagation time in isotropic uniform media, and can also be obtained by solving a three-dimensional equation for more complex media, namely another method for calculating T s is as follows:
The three-dimensional equation of the journey is Where t represents the first arrival time of the acoustic wave,The three-dimensional wave arrival time of the surface excitation form is obtained by setting a equation of the equation of solving the time deviation of each excitation array element to the space for the speed value of the three-dimensional space rectangular coordinate (x, y, z), wherein x, y, z are the directions of the three-dimensional space rectangular coordinate system respectively, and the time T s from the acoustic wave signal emitted by the area array sensor to the imaging point is further obtained.
2. The method for detecting the in-pile karst based on the array transducer according to claim 1, wherein the releasing mode in the step S1 includes sinking or suspending:
When the sinking mode is used, the transducer is sunk into the pile bottom by dead weight, and after the transducer is attached to the pile bottom surface, the array elements on the array transducer are controlled to transmit and receive ultrasonic signals;
When the suspended mode is used, the array transducer is lifted to a preset height from the bottom surface of the pile, and the array elements on the array transducer are controlled to transmit and receive ultrasonic signals so as to detect karst at the shallow part of the pile bottom.
3. The method for in-pile karst detection based on array transducer according to claim 2, wherein when using suspended mode, the array transducer can be placed side by side to be close to the pile wall, and the array element on the array transducer is controlled to transmit and receive ultrasonic signals to detect the pile Zhou Yanrong.
4. The method for in-pile karst detection based on array transducers of claim 1, wherein S2 comprises in particular a point scan mode, a line scan mode or a face scan mode; wherein the method comprises the steps of
Point scan mode: each array element of the array transducer area array transmits ultrasonic signals in sequence, and other array elements or all array elements synchronously receive the signals until a full matrix scanning data set is acquired;
Line scan mode: each row or each column of array elements of the array transducer sequentially transmits ultrasonic signals, and other array elements or all array elements synchronously receive signals until full linear array scanning data are acquired;
Surface scanning mode: and transmitting signals by the whole array surface of the array transducer, and synchronously receiving signals by all array elements until the surface array scanning data are acquired.
5. The method for in-pile karst detection based on array transducer according to claim 1, wherein S2 specifically comprises:
The method comprises the steps of controlling all array elements to synchronously transmit signals or respectively and independently controlling the excitation delay time of each array element, collecting data by adopting a phase control scanning mode, and specifically adopting the phase control scanning mode to comprise the following steps:
Rotary scanning means, particularly along azimuth Fixed direction, control inclinationScanning and inclination angleScanning according to a preset angle range, and changing azimuth angle after scanning according to a fixed directionUntil the scanning in the direction of 360 degrees is completed;
Or a grid scanning mode, scanning is carried out according to rows or columns, the inclination angle of the scanning rows or columns is given, and then the scanning is carried out according to the wave velocity deflection angle of the rows or columns.
6. The array transducer-based in-pile karst detection method of claim 1, wherein S2 further comprises: transmitting pulse ultrasonic signals by using array elements on edges or corners of the array transducer, taking ultrasonic signals received by receiving array elements which are in the same row or column as the transmitting array elements and far away from the transmitting array elements, respectively taking the difference between the time for receiving the ultrasonic signals by two adjacent receiving array elements to obtain delay time, and combining the array element spacing to calculate the initial propagation speed;
all the preliminary propagation speeds are averaged to obtain the propagation speed of the ultrasonic waves in the bedrock.
7. An array transducer-based pile bottom karst detection system for implementing an array transducer-based in-pile karst detection method according to any one of claims 1 to 6, comprising:
The data acquisition module is used for throwing the array transducer into the pile and controlling the array element on the array transducer to transmit and receive ultrasonic signals;
and the imaging module records the amplitude values at all times in the ultrasonic wave propagation process and gives the amplitude values to imaging points to obtain an imaging model.
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| CN112817039A (en) * | 2021-01-22 | 2021-05-18 | 中铁第四勘察设计院集团有限公司 | Three-dimensional detection method, device, equipment and storage medium |
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| CN112817039A (en) * | 2021-01-22 | 2021-05-18 | 中铁第四勘察设计院集团有限公司 | Three-dimensional detection method, device, equipment and storage medium |
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