CROSS REFERENCE TO RELATED APPLICATION

This application claims priority of Application No. 201811133464.4 filed in China on Sep. 27, 2018, under U.S.C. § 119, the entire contents of which are hereby incorporated by reference.

FIELD OF TECHNOLOGY

The following relates to a field of pile detection, in particular to a pile integrity detection system based on cross-hole sonic logging method.

BACKGROUND

The bored cast-in-place pile is a concealed work, and the quality of poured pile shafts is critical to the stability and safety of supporting superstructures. Due to the effects of the hydro geological conditions in the construction site, the technical level of technicians and the construction process, the pouring pile shafts commonly have some flaws of intercalated soil, cavity, segregation and brokenness. Therefore, the pile foundation needs to carry out the integrity detection before use, which is of great significance to the reliable judgment of the bearing capacity of pile foundations. The current methods for evaluating pile integrity mainly include core drilling method, low strain integrity testing method, high strain dynamic testing method and cross-hole sonic logging method. Each method has its own technical characteristics and range of application. The cross-hole sonic logging method is widely used to perform the pile foundation integrity detection in the fields of construction projects, hydraulic projects, transportation projects, due to its relatively flexibility, convenience, reliability, reasonable cost and wide range of application.

The cross-hole sonic logging method to judge the integrity of the pile is based on the observation and analysis of the acoustic wave parameters such as the propagation velocity and amplitude of wave in different media. In the prior art, the detection process generally includes, the transmitter and the receiver are placed in the measuring tubes inside the pile foundation, then the acoustic wave data between the transmitter and the receiver is collected, recorded, and then stored using the acoustic wave measuring instrument. The integrity of pouring pile shafts will therefore be evaluated according to the wave signal data and the known discrimination method, subsequently a detection report can be made. However, the accuracy and efficiency of the current detection, to a certain extent, depend on the selection of the discrimination method and the influence of the construction environment. The inclination of the tubes during construction and the unevenness of the pouring concrete of piles at different heights will both cause the variation of the acoustic wave measurement data along the pile depth. The difference in the arrival time of the first wave for various measuring points on the same acoustic wave detecting section may result in the critical value and the abnormal point analyzed by the mathematical statistical method or the PSD method, which is different from the actual one. In order to avoid misjudgment, some acoustic wave signal data needs to be corrected manually, which consumes a lot of manpower and time and reduces the detection efficiency.

SUMMARY

An aspect relates to a pile integrity detection system based on cross-hole sonic logging method, which does not require the operator to perform any revision to the wave energy data, realizing automated pile integrity detection. It greatly improves the efficiency of detection and reduces the error rate.

The following provides the following technical solution.

A pile integrity detection system based on cross-hole sonic logging method, comprising a field detection module, a communication transmission module and a cloud computing module; the field detection module is connected to the cloud computing module via the communication transmission module;

The field detection module comprises an ultrasonic detector which is connected to the communication transmission module; the ultrasonic detector comprises a controller, a transmitter and a receiver, the transmitter and the receiver are respectively connected to the controller via cables;

The controller is configured to, when receiving a sending instruction from the user, send an acoustic wave transmitting instruction to the transmitter, receive wave energy data of the receiver, and receive project data inputted by the user;

The transmitter is disposed and can be moved up/down in a first measuring tube of a to-be-detected pile, and can emit acoustic waves to the receiver according to the acoustic wave transmitting instruction which indicates the frequency and time period of emitting the acoustic wave;

The receiver is disposed and can be moved up/down in a second measuring tube of the to-be-detected pile, receiving acoustic waves emitted by the transmitter, then converting the received acoustic waves into wave energy data and transmitting it to the controller; the receiver and the transmitter are always disposed at same height, moved up/down simultaneously; the project data includes a centre-to-centre distance between the first measuring tube and the second measuring tube, and a compression wave velocity of the pouring concrete of the to-be-detected pile; the wave energy data includes an acoustic energy and a travel time of the acoustic waves, and the travel time is a period the acoustic wave reached the receiver from the transmitter;

The communication transmission module is configured to, when receiving a transmission instruction from the user, transmit the project data and the wave energy data in the field detection module to the cloud computing module;

The cloud computing module is configured to perform data analysis on the project data and the wave energy data by using a preset wave energy analysis method to determine the integrity of the to-be-detected pile.

Further, the wave energy data includes a wave energy and a travel time of the acoustic wave which was emitted by the transmitter, and was received by the receiver at different heights of several detecting sections; the detecting section is composed of any two measuring tubes within the to-be-detected pile;

The cloud computing module is configured to perform the following steps to implement data analysis on the wave energy data and the project data, determine the integrity of the to-be-detected pile:

S1. Calculating the total wave energy Mijof the acoustic wave which was emitted by the transmitter, and was received by the receiver at height j of a detecting section i in a preset time period [tijk,tijn]; the calculation formula is as follows:
Mij=∫tijktijn|Ap(ζ)|dζ

Wherein

i, j, k, and n are positive integers;

Ap(ζ) is the wave energy which was received by the receiver at travel time ζ;

tijkis the travel time of the acoustic wave which was received by the receiver at height j of a detecting section i at time k;

tijk=li/Vp, where liis the centre-to-centre distance between two measuring tubes in the detection section i, Vpis the compression wave velocity of the pouring concrete of the to-be-detected pile;

Mijis the total wave energy at height j of the detecting section i in time period [tijk,tijn], and [tijk,tijn] is 4 to 6 times the time period of emitting the acoustic wave;

S2. Calculating the total wave energy Mijby using a trapezoidal integration method, like the following formula:

Mij=∑m=kn⁢[12⁢(Ap⁡(tijm)+Ap⁡(tijm+1))⁢Δ⁢⁢t]

Wherein: m is a positive integer; Δt is the time subinterval of receiving the acoustic wave by the receiver;

S3. Performing dimensionless processing on the total wave energy Mijto obtain the dimensionless total wave energyMijwhich was received by the receiver at height j of the detecting section i in a preset time period [tijk,tijn], by the following formula:

M_ij=∑m=kn⁢[12⁢(Ap⁡(tijm)+Ap⁡(tijm+1))⁢Δ⁢⁢t]/(tijn-tijk)

S4. Comparing the dimensionless total wave energyMijwith a preset threshold; when the dimensionless total wave energyMijis less than the preset threshold, the cloud computing module determines that some flaws exist at the height j of the detecting section i in the to-be-detected pile; otherwise, the cloud computing module determines that the height j of the detecting section i in the to-be-detected pile is normal.

Further, the cloud computing module is further configured to perform the following steps to implement the setting of the preset threshold:

S5. Getting a plurality of dimensionless total wave energyMi1Mi2, . . . ,Mihwhich were received by the receiver at height positions 1, 2, . . . , h of the detecting section i by performing the above steps S1-S3;

S6. Sorting all the dimensionless total wave energies, and deleting h′ minimum values and h′ maximum values, and calculate an average relative total wave energywhich were received by the receiver in the detecting section i, by the following formula:

M_)i=1h-2⁢h′⁢∑j=1h-2⁢h′⁢M_ij

Wherein: h and h′ are positive integers, and h′=2h/5;

S7. Setting the preset threshold to 0.5.

Further, the field detection module further comprises a photographing module which is connected to the communication transmission module, and is configured to record an audio and video data of the testing site when the operator detects the to-be-detected pile, and subsequently the audio and video data are transmitted to the cloud computing module via the communication transmission module.

Further, the communication transmission module further comprises an encryption module which is configured to encrypt a to-be-transmitted data before transmitting the data; the cloud computing module further comprises a decryption module which is configured to decrypt the data after receiving the encrypted data.

Further, the ultrasonic detector further comprises a transmission mechanism which is connected to a controller and a cable respectively, and the controller sends a traction command to the transmission mechanism when receiving a transmission instruction from the user; the transmission mechanism is configured to receive the traction command from the controller, and tow the cable controlling the simultaneous movement of the transmitter and the receiver according to the traction command; the traction command indicates a traction speed of the transmission mechanism.

Further, the transmission mechanism comprises a driving motor and a transmission wheel;

The transmission wheel is fixed to a driving shaft of the driving motor, and is connected to the cable; and

The drive motor is connected to the controller, when the driving motor receives the traction command, and can drive the driving shaft to rotate subsequently drive the drive wheel to tow the cable, whereby the transmitter and the receiver can be moved up/down simultaneously.

Further, the cloud computing module further comprises a report generating module which can generate a detection report for a to-be-detected pile by filling the integrity information of the to-be-detected pile into a report template.

Further, the field detection module further comprises a storage which can store the wave energy data, the project data, a geographical location information, and the image data.

Further, the field detection module further comprises a GPS locator which is connected to the communication transmission module, and is configured to acquire a geographic location information of the to-be-detected pile, and the geographic location information is transmitted to the cloud computing module via the communication transmission module, then the cloud computing module compares the geographic location information with a preset geographic location information of the to-be-detected pile to verify the authenticity of the wave energy data.

Comparing to the prior art, the advantage of the present invention is as follows:

The present invention discloses a pile integrity detection system based on cross-hole sonic logging method. The operator sets the ultrasonic detector into the measuring tubes of the to-be-detected pile, subsequently inputs the project data and activates the ultrasonic detector, by an acoustic wave transmission among a transmitter and a receiver, a wave energy data of the to-be-detected pile can be obtained, and the wave energy data and the project data will be automatically transmitted to the cloud computing module. Thereby, the integrity of the to-be-detected pile can be reasonably determined without any manual analysis to the wave energy data, preventing from any error or deflection due to manual operation, whereby it greatly improves the accuracy and efficiency of detection and reduces the error rate.

