JP7629376B2 - Exploration device, exploration method, and exploration system - Google Patents

Description

The present invention relates to an exploration device, exploration method, and exploration system for underground buried objects in construction work.

In urban civil engineering and construction, underground buried objects are surveyed before construction begins. For example, Patent Document 1 discloses a reflection method survey system that includes an oscillator that is installed on the ground surface and generates vibrations underground using a piezoelectric or magnetostrictive element, a detector that detects the reflected waves that are reflected from buried objects underground or from strata boundaries and reach the ground surface, and a position estimation device that estimates the position of the buried object or strata boundary using the detected reflected waves, where the position estimation device applies a sweep wave in which the oscillator's vibration frequency is changed from high to low to estimate the position.

JP 2010-139451 A

However, the above technology has the problem that it is difficult to fully grasp the shape of buried objects, which is necessary to identify the buried objects.

The present invention was made in consideration of the above problems, and one example of the objective of the invention is to provide an exploration device that can grasp the shape of buried objects underground.

In order to solve the above problem, the present invention provides a method for obtaining waveform data from a plurality of points on the ground, the distance between which is smaller than the size of an embedded object, by exciting the ground with an excitation device; a total travel time calculation means for calculating a total travel time of elastic waves from an excitation point of the excitation device to one of the receiving points; an amplitude superimposition means for superimposing the amplitude of the waveform data at each of the receiving points according to the total travel time; and a reflection point identification means for identifying a reflection point at the embedded object according to the superimposed amplitude, and the waveform data obtained by exciting the ground with the excitation device at a plurality of different positions is stored in the storage means. the shape of the buried object is identified from the multiple reflection points calculated by a data set ; the total travel time calculation means calculates the total travel time of the elastic waves from the excitation point of the excitation device to one of the receiving points among the points, via underground scattering points set at intervals smaller than the size of the buried object; the amplitude stacking means sets the amplitude of the waveform data at the one receiving point during the total travel time as the amplitude of the scattering point, and stacks the amplitudes of the scattering points from each receiving point for each scattering point; and the reflection point identification means identifies the reflection point from the scattering points in accordance with the amplitude of the stacked scattering points .

In a second aspect of the present invention, in the exploration device according to the first aspect, the reflection point identifying means identifies a point at which the superimposed amplitude is maximum as the reflection point.

The invention described in claim 3 is characterized in that, in the exploration device described in claim 1 or 2 , the waveform data superimposed by the amplitude superimposition means is waveform data obtained by calculating correlation data between the acquired waveform data and excitation waveform data generated by the excitation device, extracting a waveform of components in a predetermined frequency range from the correlation data, and muting the rising portion of the waveform generated by the excitation device from the extracted waveform.

The invention described in claim 4 is characterized in that, in the exploration device described in any one of claims 1 to 3 , it further comprises a wide-area waveform data acquisition means for acquiring wide-area waveform data from a plurality of points spaced apart by an interval equal to or greater than the size of the buried object by vibration excited by the vibration excitation device, and a buried object position estimation means for estimating the depth and position on the ground of the buried object from the wide-area waveform data.

The invention described in claim 5 is characterized in that, in the exploration device described in claim 4 , the positions of the vibration excitation device that are farthest from each other among the multiple different positions of the vibration excitation device are more than twice the estimated depth of the buried object.

The invention described in claim 6 is characterized in that in the exploration device described in any one of claims 1 to 5 , the acquisition means acquires the waveform data from a vibration receiving sensor installed on the ground.

The invention described in claim 7 is the exploration device described in any one of claims 1 to 5 , characterized in that the acquisition means acquires the waveform data from a non-contact optical vibrometer.

The invention described in claim 8 includes an acquisition step in which an acquisition means acquires waveform data from a plurality of points on the ground at intervals smaller than the size of an embedded object by exciting the ground with an excitation device, a total traveltime calculation step in which a total traveltime calculation means calculates a total traveltime of elastic waves from an excitation point of the excitation device to one of the points, an amplitude stacking step in which an amplitude stacking means stacks the amplitude of the waveform data at each of the one receiving points according to the total traveltime, and a reflection point identification step in which a reflection point identification means identifies a reflection point at the embedded object according to the stacked amplitude, the shape of the buried object is identified from the multiple reflection points calculated from the waveform data obtained by exciting the buried object at a predetermined frequency , the total travel time calculation means calculates the total travel time of the elastic waves from the excitation point of the excitation device to one of the receiving points among the points, via underground scattering points set at intervals smaller than the size of the buried object, the amplitude stacking means sets the amplitude of the waveform data at the one receiving point during the total travel time as the amplitude of the scattering point, and stacks the amplitudes of the scattering points from each receiving point for each scattering point, and the reflection point identification means identifies the reflection point from the scattering points in accordance with the amplitude of the stacked scattering points .

The invention described in claim 9 is an exploration system including an excitation device for vibrating the ground, a receiving device for receiving the vibrations generated by the excitation device, and an exploration device, the exploration device including: an acquisition means for acquiring waveform data from the receiving device when the ground is excited by the excitation device and the waveform data is from a plurality of points on the ground that are spaced apart from each other by an interval smaller than the size of an underground object; a total travel time calculation means for calculating a total travel time of elastic waves from the excitation point of the excitation device to one receiving point among the points; an amplitude superimposition means for superimposing the amplitude of the waveform data at each receiving point according to the total travel time; and a reflection point identification means for identifying a reflection point at the underground object according to the superimposed amplitude. and identifying a shape of the buried object from a plurality of reflection points calculated from the waveform data obtained by excitation by the excitation device at a plurality of different positions , the total travel time calculation means calculates the total travel time of the elastic wave from the excitation point of the excitation device to one of the receiving points among the positions, via underground scattering points set at intervals smaller than the size of the buried object, the amplitude stacking means sets the amplitude of the waveform data at the one receiving point during the total travel time as the amplitude of the scattering point, and stacks the amplitudes of the scattering points from each receiving point for each scattering point, and the reflection point identification means identifies the reflection point from the scattering points in accordance with the amplitude of the stacked scattering points .

According to the present invention, the ground is excited by an excitation device, waveform data is obtained from multiple points on the ground spaced apart from each other by a distance smaller than the size of the buried object, the total travel time of the elastic waves from the excitation point to one of the receiving points is calculated, the amplitude of the waveform data at each receiving point is superimposed according to the total travel time, and a reflection point at the buried object is identified according to the superimposed amplitude, and the shape of the buried object underground can be grasped from the multiple reflection points calculated from the waveform data obtained by excitation by excitation devices at multiple different positions.

1 is a schematic diagram showing an example of a general configuration of an exploration system according to an embodiment of the present invention. FIG. 2 is a block diagram showing an example of a schematic configuration of the information processing apparatus shown in FIG. 1 . 1 is a flowchart illustrating an example of the operation of the exploration system according to the embodiment. 11 is a graph showing an example of waveforms of a plurality of vibration receiving sensors. FIG. 2 is a schematic diagram showing an example in which a vibration excitation device is moved in the exploration system of FIG. 1 . FIG. 13 is a diagram illustrating an example of an imaging process. FIG. 13 is a diagram illustrating an example of an imaging process. FIG. 11 is a diagram showing an example of calculated reflection points. FIG. 11 is a diagram showing an example of calculated reflection points. FIG. 13 is a diagram showing an example of a search result. 4 is a flowchart showing a subroutine of the scattered wave imaging process in FIG. 3 . 1 is a graph showing an example of a waveform. 1 is a graph showing an example of a waveform. 1 is a graph showing an example of a waveform. 1 is a graph showing an example of a waveform. 10 is a flowchart showing a subroutine of the depth migration of FIG. 9; FIG. 2 is a schematic diagram showing the relationship between a vibration source point, a vibration receiving point, and a scattering point. FIG. 2 is a schematic diagram showing the relationship between a vibration source point, a vibration receiving point, and a scattering point. A schematic diagram showing an example of the general configuration of an exploration system related to a second embodiment.

Embodiments of the present invention will be described below with reference to the drawings. Note that the embodiments described below are embodiments in which the present invention is applied to an exploration system or the like.

[1. Overview of the configuration and functions of the exploration system and each device]
(1.1 Overview of the exploration system configuration and functions)

First, the configuration and general functions of an exploration system according to one embodiment of the present invention will be explained using FIG. 1.

Figure 1 is a schematic diagram showing an example of the general configuration of an exploration system according to this embodiment.

As shown in FIG. 1, the exploration system 1 according to this embodiment includes a vibration generating device 10 that applies vibrations to the ground G, a vibration receiving device 20 that receives the vibrations of the ground G, and an exploration device 30 that analyzes waveform data from the vibration receiving device 20 to explore buried objects 5.

Buried objects 5 in construction work are objects that are 1 m or deeper, such as sewer pipes, utility conduits, subway tunnels, etc. Buried objects 5 are also structures such as foundations, slabs, retaining walls, and pressure plates that are left behind after construction. Buried objects 5 are also piles, H-shaped steel, steel sheet piles, etc. that are left behind after construction. Buried objects 5 exist at depths of up to about 20 m, for example. It is preferable that buried objects are 2 m or deeper.

The vibration excitation device 10 has a vibrator. The vibration excitation device 10 propagates elastic waves from the surface to underground using a modulated signal in a frequency band of several tens of Hz to several hundred Hz. The vibration excitation device 10 is not only placed directly above the buried object 5, but also moved to a position sufficiently distant from the buried object 5 (for example, more than twice the expected depth of the buried object 5).

The vibrator of the vibration excitation device 10 is, for example, an electric motor. The excitation force is 450 [N]. The vibration to be applied may be a longitudinal wave or a transverse wave, but a longitudinal wave is preferable. The vibrator may also be a piezoelectric element or a magnetostrictive element.

The vibration receiving device 20 is composed of multiple vibration receiving sensors 20a, and converts vibrations of the ground G into waveform data and outputs it to the exploration device 30. Each vibration receiving sensor 20a is arranged on the ground G at a predetermined interval in a grid or measurement line pattern. As shown in FIG. 1, the vibration receiving sensors 20a arranged at a predetermined interval in one direction are displayed. Instead of a grid-shaped sensor, a measurement line-shaped sensor may be used, which is shifted in a direction that is not parallel to the direction in which the vibration receiving sensors 20a are arranged. The vibration receiving sensor 20a is an example of a vibration receiving sensor installed on the ground.

The vibration receiving sensor 20a is an installed sensor such as a mechanical sensor such as a spring type or MEMS, an electromagnetic sensor such as a coil type or geophone, or a piezoelectric sensor such as a piezoelectric element or acceleration pickup.

For wide-area measurements, the grid spacing of the vibration receiving sensor 20a is preferably, for example, between 50 cm and several meters, approximately half the size of the expected buried object.

For detailed measurements, the lattice spacing of the vibration receiving sensor 20a is smaller than the size of the buried object 5. For example, it is smaller than the diameter of the cylindrical buried object 5, and is a high-density spacing of, for example, several centimeters to several tens of centimeters.

The exploration device 30 vibrates the vibration excitation device 10 at a predetermined frequency and acquires waveform data from the vibration receiving device 20.

Construction work includes civil engineering works such as open cut construction and shield construction. Other construction works include retaining walls, ground improvement work, structure demolition work, and underground obstacle removal work.

(1.2 Configuration and Function of the Exploration Device 30)
Next, the configuration and functions of the exploration device 30 will be described with reference to FIG.

Figure 2 is a block diagram showing an example of the general configuration of the exploration device 30.

As shown in FIG. 2, the exploration device 30, which functions as a computer, has a communication unit 31, a display unit 32, a memory unit 33, an operation unit 34, an input/output interface unit 35, and a control unit 36. The control unit 36 and the input/output interface unit 35 are connected via a system bus 37. For example, the exploration device 30 is a mobile terminal such as a personal computer, a portable wireless telephone including a smartphone, or a PDA.

The communication unit 31 is connected to the vibration excitation device 10 and transmits a modulated signal of a vibration pattern to the vibration excitation device 10. The communication unit 31 is connected to each vibration receiving sensor 20a of the vibration receiving device 20 and acquires detected waveform data from the vibration receiving sensor 20a.

The display unit 32 is composed of, for example, a liquid crystal display element or an organic EL (Electro Luminescence) element. The display unit 32 displays the results of the imaging process.

The storage unit 33 is, for example, a silicon disk drive or a hard disk drive. The storage unit 33 stores various programs for controlling the exploration device 30. Examples of the various programs include an operating system. The various programs may be acquired via a network such as a wireless communication network, or may be recorded on a recording medium such as a CD or DVD and read via a drive device.

The storage unit 33 stores the waveform data transmitted from the vibration receiving device 20 in association with the channel number and sensor ID of each vibration receiving sensor 20a. The storage unit 33 stores the placement information of each vibration receiving sensor 20a in association with the channel number of the vibration receiving sensor 20a.

The operation unit 34 is composed of, for example, a keyboard and a mouse. The display unit 32 of the operation unit 34 may be a touch switch type display panel such as a touch panel.

The input/output interface unit 35 is an interface between the communication unit 31 etc. and the control unit 36.

The control unit 36 has, for example, a CPU, a ROM, and a RAM. The control unit 36 has a CPU that reads and executes various programs stored in the ROM, the RAM, and the storage unit 23.

[2. Example of exploration system operation]
Next, an example of the operation of the exploration system will be described with reference to FIG. 3 to FIG. 12B.

As shown in FIG. 3, the exploration system 1 performs wide-area measurements (step S1). The vibration excitation device 10 is installed near the center of the site where an excavation plant or the like is to be performed. Each vibration receiving sensor 20a of the vibration receiving device 20 is arranged in a grid or survey line pattern at intervals of several tens of centimeters to several meters to the side or around the site where the vibration excitation device 10 is installed. It is preferable that the spacing between the vibration receiving sensors 20a is greater than the size of the anticipated buried object.

Next, the control unit 36 of the exploration device 30 stores the placement information of each vibration receiving sensor 20a in the memory unit 33 in association with the channel number of the vibration receiving sensor 20a, etc.

Next, the control unit 36 of the exploration device 30 excites the vibration excitation device 10. The vibration excitation device 10 excites the ground G. The control unit 36 acquires waveform data, which is an example of wide-area waveform data, from each vibration receiving sensor 20a of the vibration receiving device 20. The control unit 36 associates the acquired vibration reception waveform data with the channel number of the vibration receiving sensor 20a, etc., and stores it in the memory unit 33. The control unit 36 also stores the vibration excitation waveform data that excited the vibration excitation device 10 in the memory unit 33.

In this way, the exploration device 30 functions as an example of a wide-area waveform data acquisition means that acquires wide-area waveform data from multiple points spaced apart by an interval equal to or greater than the size of the buried object through vibration excited by a vibration excitation device.

Next, the exploration system 1 identifies the approximate location of the buried object 5 (step S2). Specifically, the control unit 36 of the exploration device 30 identifies the approximate location of the buried object 5 from the acquired waveform data. For example, multiple measurement lines are set over a wide range, and as shown in FIG. 4, the position of the measurement point of peak p (the measurement point where the scattered wave reached the fastest) of the waveform where the scattered waves of the measured waveform data are arranged in a convex shape is determined to be the location of the buried object. The approximate depth of the buried object is obtained by estimating the ground speed that matches the convex distribution of the scattered waves. The ground speed is estimated from the time of the scattered waves that roughly match the scattered wave line, as shown in FIG. 4.

In this way, the exploration device 30 functions as an example of a buried object position estimation means that estimates the depth and position above the ground of the buried object from the wide-area waveform data.

Next, the exploration system 1 performs detailed measurements (step S3). As shown in FIG. 1, the vibration excitation device 10 is installed near the approximate location of the identified buried object 5. The vibration receiving sensors 20a of the vibration receiving device 20 are arranged in a grid or survey line pattern with intervals of several centimeters to several tens of centimeters to the side or around the location where the vibration excitation device 10 is installed. The interval between the vibration receiving sensors 20a is smaller than the size of the expected buried object.

Next, the control unit 36 of the exploration device 30 stores the installation information of the vibration excitation device 10 and the arrangement information of each vibration receiving sensor 20a in the memory unit 33 in association with the channel number of the vibration receiving sensor 20a, etc. Note that the vibration excitation device 10 and the vibration receiving device 20 may have a GPS sensor. The latitude and longitude information acquired by the GPS sensor may be included in the installation information of the vibration excitation device 10 and the arrangement information of the vibration receiving sensor 20a.

Next, the control unit 36 of the exploration device 30 excites the vibration excitation device 10. The vibration excitation device 10 excites the ground G. The control unit 36 acquires waveform data from each vibration receiving sensor 20a of the vibration receiving device 20. The control unit 36 stores the acquired waveform data in the memory unit 33 in association with the channel number of the vibration receiving sensor 20a, etc. The control unit 36 also stores the vibration excitation waveform data that caused the vibration excitation device 10 to vibrate in the memory unit 33. In the memory unit 33, the vibration reception waveform data and the positioning information of the vibration receiving sensor 20a are associated. In the memory unit 33, the vibration excitation waveform data and the installation information of the vibration excitation device 10 are associated.

In this way, the exploration device 30 functions as an example of an acquisition means that acquires waveform data from multiple points on the ground that are spaced apart from each other and are smaller than the size of the buried object when the ground is excited by the excitation device.

Next, as shown in FIG. 5, the vibration excitation device 10 is moved, and each vibration receiving sensor 20a of the vibration receiving device 20 is arranged in a grid or line pattern with intervals of several centimeters to several tens of centimeters around or to the side of the location where the vibration excitation device 10 is installed.

Next, the control unit 36 of the exploration device 30 stores in the memory unit 33 the installation information of the vibration excitation device 10 and the positioning information of each vibration receiving sensor 20a in association with the channel number of the vibration receiving sensor 20a, etc.

Next, the control unit 36 of the exploration device 30 excites the vibration excitation device 10. The vibration excitation device 10 excites the ground G. The control unit 36 acquires waveform data from each vibration receiving sensor 20a of the vibration receiving device 20. The control unit 36 stores the acquired received vibration waveform data in association with the channel number of the vibration receiving sensor 20a, etc.

In this manner, the vibration excitation device 10 is moved several times to repeat detailed measurements. It is preferable to move the vibration excitation device 10 so as to cross the buried object 5. Furthermore, among the multiple different positions of the vibration excitation device 10, the positions of the vibration excitation device 10 that are furthest from each other are more than twice the estimated depth of the buried object 5.

Next, the exploration system 1 performs imaging processing of the scattered waves (step S4). Specifically, the control unit 36 of the exploration device 30 reads out the received waveform data and the generated waveform data from the memory unit 33, and performs imaging processing in a subroutine for the scattered wave imaging processing described below, to obtain an image 40 of the imaging processing of the scattered waves of the buried object 5, as shown in Figures 6A and 6B. In image 40, the horizontal axis is distance on the ground G, and the vertical axis is depth. Image 40 is an image of the scattered waves, and is an example of superimposed amplitude. Note that Figures 6A and 6B are images 40 at different excitation points to which the excitation device 10 has been moved.

Next, the exploration system 1 extracts reflection points (step S5). Specifically, as shown in Figures 7A and 7B, the control unit 36 of the exploration device 30 extracts reflection points 41 with maximum amplitude in each image 40 at different excitation points to which the excitation device 10 is moved. In this way, the control unit 36 extracts the peaks of the imaged scattered waves as reflection points. Each point in the image 40 is a scattering point set when calculating the depth migration.

In this way, the exploration device 30 functions as an example of a reflection point identification means that identifies a reflection point at the buried object according to the superimposed amplitude. The exploration device 30 functions as an example of a reflection point identification means that identifies the reflection point from the scattering point according to the amplitude of the superimposed scattering point. The exploration device 30 functions as an example of a reflection point identification means that identifies the point at which the superimposed amplitude is maximum as the reflection point.

Next, the exploration system 1 creates point cloud data of the reflection points (step S6). Specifically, the control unit 36 of the exploration device 30 collects the extracted reflection points 41 and creates point cloud data 42 of the reflection points 41, as shown in FIG. 8. The shape of the top surface of the buried object 5 is represented by the point cloud data 42. In this way, the scattering points for the excitation points are plotted on a two-dimensional cross section to create a buried pipe exploration result as shown in FIG. 8.

In this way, the exploration device 30 identifies the shape of the buried object from the multiple reflection points calculated using the waveform data obtained by exciting the excitation device at multiple different positions.

Next, the exploration system 1 displays the results of the buried object exploration (step S7). Specifically, the control unit 36 of the exploration device 30 displays the point cloud data 42 on the display unit 32 as the results of the buried object exploration.

(2.1 Subroutine for Scattered Wave Imaging Processing)
Next, the subroutine for the imaging process of the scattered wave will be described with reference to FIG. 9 to FIG. 10D.

As shown in FIG. 9, the exploration system 1 obtains a cross-correlation waveform between the excitation waveform data and the received waveform data (step S10). The control unit 36 of the exploration device 30 calculates the cross-correlation between the received waveform data and the excitation waveform data, for example, as shown in FIG. 10A, to obtain the cross-correlation waveform data as shown in FIG. 10B. The cross-correlation waveform data is an example of correlation data between the acquired waveform data and the excitation waveform data generated by the excitation device. By calculating the cross-correlation between the modulation signal of the excitation device and the measured data, noise is reduced and distance resolution is improved, and scattered waves from the underground buried object 5 are separated from other waves.

Next, the exploration system 1 performs bandpass filter processing (step S11). Specifically, the control unit 36 removes low-frequency components below a predetermined value and high-frequency components above a predetermined value from the cross-correlation waveform data to obtain waveform data such as that shown in FIG. 10C. The bandpass filter processing is an example of extracting waveforms of components in a predetermined frequency range from the correlation data.

Next, the exploration system 1 performs a muting process (step S12). Specifically, as shown in FIG. 10D, the control unit 36 performs the muting process by applying a muting function to remove the rising portion of the waveform that corresponds to the direct wave from the excitation device 10. Note that FIG. 10D shows the muted portion. In this way, the control unit 36 mutes the rising portion of the waveform caused by the excitation device from the extracted waveform.

Examples of the mute function include a sigmoid function and a step function. Any mute function can be used as long as it reduces the amplitude during the time period affected by the direct wave from the vibration device 10. The above process from cross-correlation to mute processing constitutes pre-processing.

Next, the exploration system 1 performs depth migration processing (step S13). Specifically, the control unit 36 of the exploration device 30 performs depth migration processing on each muted waveform data in a depth migration processing subroutine described below, and calculates an image 40 of the imaging processing of the scattered waves of the buried object 5, as shown in Figures 6A and 6B.

Next, the exploration system 1 outputs the imaging processing result (step S14). Specifically, the control unit 36 of the exploration device 30 outputs an image 40 of the depth migration processing result.

(2.2 Depth Migration Processing Subroutine)
Next, the subroutine of the depth migration process will be described with reference to FIG. 11 to FIG. 12B.

As shown in FIG. 11, the exploration system 1 determines the elastic wave velocity of the ground (step S20). Specifically, the control unit 36 of the exploration device 30 applies a residual moving-out method, a coherency inversion method, or the like to the received waveform data or the waveform data preprocessed as described above to construct a velocity model and determine the elastic wave velocity of the ground of the ground G. In this way, an elastic wave velocity analysis is performed using the acquired data to obtain the underground elastic wave velocity, thereby converting the time series data into spatial data.

Next, the exploration system 1 calculates the travel time from the excitation point to the underground scattering point and the travel time from the scattering point to the receiving point (step S21). Specifically, as shown in FIG. 12A, the control unit 36 of the exploration device 30 calculates the travel time T1 from the excitation point A to the underground scattering point P and the travel time T2 from the scattering point P to the receiving point B based on the determined elastic wave velocity.

Next, the exploration system 1 calculates the total travel time (step S22). Specifically, the control unit 36 of the exploration device 30 calculates the total travel time T1+T2 of the travel time T1 and the travel time T2.

In this way, the exploration device 30 functions as an example of a total travel time calculation means that calculates the total travel time of elastic waves from the excitation point of the excitation device to one of the receiving points of the locations. The exploration device 30 functions as an example of a total travel time calculation means that calculates the total travel time of elastic waves from the excitation point of the excitation device to one of the receiving points of the locations via underground scattering points set at intervals smaller than the size of the buried object.

Next, the exploration system 1 determines the amplitude of the total travel time of the waveform excited at the excitation point and received at the receiving point as the amplitude of the scattering point (step S23). Specifically, the control unit 36 of the exploration device 30 determines the amplitude of the total travel time T1+T2 for the muted waveform data measured at the receiving point B as shown in FIG. 10D as the amplitude of the scattering point P.

Next, the exploration system 1 determines whether the processing from step S20 to step S23 has been performed for all underground points and all receiving points for the excitation point (step S24). Specifically, the control unit 36 of the exploration device 30 determines whether the processing from step S20 to step S23 has been performed for all receiving points where the vibration sensor 20a is installed and all scattering points P1, P2, etc. within a range of a predetermined depth and a predetermined distance from the ground G for the excitation point where the vibration excitation device 10 is installed, as shown in FIG. 12B.

The range of the predetermined depth and the distance of the ground G is between the predetermined depth and the predetermined distance, as shown in the image 40 in FIG. 6A and FIG. 6B. The calculation mesh of the scattering points P set in the range of the predetermined depth and the distance of the ground G is preferably such that the spacing between the scattering points P is smaller than the size of the buried object 5, for example, several centimeters to several tens of centimeters.

Next, the exploration system 1 adds up all the amplitudes (step S25). Specifically, the control unit 36 of the exploration device 30 adds up the amplitudes at all the underground scattering points to superimpose them, and obtains an image 40 of the scattered wave imaging process, as shown in Figures 6A and 6B.

In this way, the exploration device 30 functions as an example of an amplitude polymerization means that polymerizes the amplitude of the waveform data at each of the one receiving points according to the total travel time. The exploration device 30 functions as an example of an amplitude polymerization means that polymerizes the amplitude of the scattering points from each receiving point for each scattering point, with the amplitude of the waveform data at the one receiving point during the total travel time being the amplitude of the scattering point.

In addition to the pre-stack depth migration mentioned above, pre-stack time migration, post-stack depth migration, and post-stack time migration algorithms may also be used.

According to the exploration device 30 of the embodiment, the ground G is excited by the excitation device 10, waveform data is obtained from multiple points on the ground G with an interval smaller than the size of the buried object 5, the total travel time of the elastic wave from the excitation point to one of the receiving points is calculated, the amplitude of the waveform data at each receiving point is superimposed according to the total travel time, and a reflection point at the buried object 5 is identified according to the superimposed amplitude, and the shape of the buried object underground can be grasped from the multiple reflection points 41 calculated from the waveform data obtained by excitation by the excitation device 10 at multiple different positions.

The shape of the buried object can be determined from the distribution of point cloud data 42 of the extracted reflection points 41. In addition, by determining the position, depth, and shape of buried objects 5 at depths of 2 to 20 m with a resolution of several tens of centimeters, it is expected that construction costs and construction time can be reduced.

The total travel time T1 + T2 of the elastic wave from the excitation point A of the excitation device 10 to one of the receiving points B is calculated via underground scattering points P set at intervals smaller than the size of the buried object 5, and the amplitude of the waveform data at one receiving point during the total travel time is taken as the amplitude of the scattering point P. The amplitudes of the scattering points from each receiving point are superimposed for each scattering point, and a reflection point 41 is identified from the scattering point according to the amplitude of the superimposed scattering points. When the ground is excited by the excitation device 10, waveform data is obtained from multiple points on the ground G at intervals smaller than the size of the buried object 5, and the reflection point 41 is identified from the scattering point according to the amplitude of the superimposed scattering points. The total travel time T1+T2 of the elastic waves from the excitation point A to one of the receiving points B is calculated via underground scattering points P set at intervals smaller than the size of the excitation point A. The amplitude of the waveform data at one of the receiving points B at the total travel time T1+T2 is set as the amplitude of the scattering point P. The amplitudes of the scattering points P from each receiving point are superimposed for each scattering point P. The reflection points 41 of the buried object 5 are identified from the scattering points P according to the amplitudes of the superimposed scattering points P. The shape of the buried object underground can be grasped from the multiple reflection points 41 calculated from the waveform data obtained from the excitation devices 10 at multiple different positions.

When the point where the superimposed amplitude is maximum is identified as reflection point 41, reflection point 41 can be identified with high accuracy.

When the waveform data to be superimposed is obtained by calculating correlation data between the acquired waveform data and excitation waveform data generated by the excitation device 10, extracting the waveform of components in a specified frequency range from the correlation data, and muting the rising portion of the waveform generated by the excitation device 10 from the extracted waveform, the direct waveform generated by the excitation device 10 is removed, and the reflection point 41 can be identified with high accuracy.

By using the vibration generated by the vibration excitation device 10, wide-area waveform data is acquired from multiple points spaced apart by an interval equal to or greater than the size of the buried object 5. When estimating the depth and position above ground of the buried object 5 from the wide-area waveform data, the locations to be measured can be narrowed down to a high density during detailed measurements, allowing for efficient measurements and shortening the measurement time.

When the position of the vibration excitation device 10 farthest from each other among multiple different positions is more than twice the estimated depth of the buried object 5, buried objects 5 distributed locally underground can be targeted according to the position of the buried object 5, and elastic waves scattered from the buried object 5 can be measured at high density near the excitation point. This allows for efficient measurement and shortens the measurement time. By applying imaging processing to data obtained by measuring elastic waves scattered from the buried object 5 at high density near the excitation point, the position, depth, and shape of buried objects 5 at a depth of 2 to 20 m can be grasped with a resolution of several tens of centimeters.

When acquiring waveform data from a vibration receiving sensor 20a installed on the ground G, scattering wave data for imaging the shape of the buried object 5 can be acquired by arranging the vibration receiving sensors 20a at high density around the vibration source point.

Second Embodiment
Next, a second embodiment will be described with reference to Fig. 13. Note that the same reference numerals are used for the same or corresponding parts as those in the first embodiment, and only different configurations and operations will be described. The same applies to the other embodiments and modifications.

In this embodiment, as shown in FIG. 13, a non-contact receiving device 21 is used instead of a stationary receiving device 20.

The vibration receiving device 21 is a non-contact vibration meter that is optical, such as a laser type or a laser Doppler type, or electromagnetic wave type, such as a radar type.

For example, the receiver 21 can be installed at the tip of a crane on a crane truck, allowing wide-area measurements to be taken from a high position.

In the detailed measurement, the height of the vibration receiving device 21 is lowered from the wide-area measurement, and the detailed measurement is performed. As in the first embodiment, the vibration excitation device 10 is moved and the detailed measurement is performed. Waveform data is obtained according to the image resolution of the vibration receiving device 21, but the waveform data may be acquired at intervals of several centimeters to several tens of centimeters.

In this way, the probe device 30 functions as an example of an acquisition means for acquiring the waveform data from a non-contact optical vibrometer.

When waveform data is acquired from a non-contact optical vibrometer, the installation work of the vibration receiving sensor 20a can be omitted.

The measurement layout can be changed from vertical to horizontal and used for tunnel forward exploration. For example, vibration excitation device 10 is installed on the excavation face of a tunnel, and waveform data is acquired from vibration receiving device 20 or vibration receiving device 21 to explore buried objects at the excavation destination.

Furthermore, the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included within the technical scope of the present invention.

1: exploration system 5: buried object 10: vibration excitation device 20, 21: vibration receiving device 30: exploration device 41: reflection point G: ground

Claims (9)

an acquisition means for acquiring waveform data from a plurality of points on the ground, the distance between the points being smaller than the size of the buried object, by an excitation device;
A total travel time calculation means for calculating a total travel time of an elastic wave from a vibration generating point of the vibration generating device to one of the vibration receiving points of the points;
an amplitude superposition means for superposing the amplitude of the waveform data at each of the one receiving points according to the total travel time;
a reflection point identifying means for identifying a reflection point at the buried object in accordance with the superimposed amplitude;
Equipped with
Identifying a shape of the buried object from a plurality of reflection points calculated from the waveform data obtained by exciting the vibration device at a plurality of different positions ;
the total travel time calculation means calculates the total travel time of the elastic waves from the excitation point of the excitation device to one of the receiving points among the points via underground scattering points set at intervals smaller than the size of the buried object;
The amplitude superimposition means superimposes the amplitude of the waveform data at the one receiving point during the total travel time as the amplitude of the scattering point, and superimposes the amplitude of the scattering point from each receiving point for each scattering point;
The exploration device , characterized in that the reflection point identifying means identifies the reflection point from the scattering points in accordance with the amplitude of the superimposed scattering points . 2. The exploration device according to claim 1, wherein the reflection point identifying means identifies a point at which the superimposed amplitude is maximum as the reflection point. 3. The exploration device according to claim 1 or 2, wherein the waveform data superimposed by the amplitude superimposing means is waveform data obtained by calculating correlation data between the acquired waveform data and excitation waveform data generated by the excitation device, extracting a waveform of components in a predetermined frequency range from the correlation data, and muting a rising portion of the waveform generated by the excitation device from the extracted waveform . a wide-area waveform data acquisition means for acquiring wide-area waveform data from a plurality of points spaced apart from each other by the vibration generated by the vibration generating device, the wide-area waveform data being acquired at intervals equal to or greater than the size of the buried object;
a buried object position estimating means for estimating the depth and the position on the ground of the buried object from the wide-area waveform data;
The exploration device according to any one of claims 1 to 3 , further comprising: 5. The exploration device according to claim 4 , wherein the positions of the vibration excitation device that are farthest from each other among the plurality of different positions of the vibration excitation device are at least twice the estimated depth of the buried object. 6. The exploration device according to claim 1, wherein the acquisition means acquires the waveform data from a vibration receiving sensor installed on the ground. 6. The exploration device according to claim 1, wherein the acquisition means acquires the waveform data from a non-contact optical vibrometer. an acquiring step in which the acquiring means acquires waveform data from a plurality of points on the ground, the intervals of which are smaller than the size of the buried object, by exciting the ground with a vibration device;
A total travel time calculation step in which a total travel time calculation means calculates a total travel time of an elastic wave from an excitation point of the excitation device to one of the receiving points of the points;
an amplitude stacking step in which an amplitude stacking means stacks the amplitude of the waveform data at each of the one receiving points according to the total travel time;
a reflection point identifying step in which a reflection point identifying means identifies a reflection point at the buried object in accordance with the superimposed amplitude;
Including,
Identifying a shape of the buried object from a plurality of reflection points calculated from the waveform data obtained by exciting the vibration device at a plurality of different positions ;
the total travel time calculation means calculates the total travel time of the elastic waves from the excitation point of the excitation device to one of the receiving points among the points via underground scattering points set at intervals smaller than the size of the buried object;
The amplitude superimposition means superimposes the amplitude of the waveform data at the one receiving point during the total travel time as the amplitude of the scattering point, and superimposes the amplitude of the scattering point from each receiving point for each scattering point;
The exploration method, wherein the reflection point identifying means identifies the reflection point from the scattering points in accordance with the amplitude of the superimposed scattering points . An exploration system including a vibration generating device that generates vibrations on the ground, a vibration receiving device that receives vibrations generated by the vibration generating device, and an exploration device,
The exploration device is
an acquisition means for acquiring waveform data from the vibration receiving device, the waveform data being obtained from a plurality of points on the ground that are spaced apart from each other by an interval smaller than the size of the buried object when the ground is excited by the vibration generating device;
A total travel time calculation means for calculating a total travel time of an elastic wave from a vibration generating point of the vibration generating device to one of the vibration receiving points of the points;
an amplitude superposition means for superposing the amplitude of the waveform data at each of the one receiving points according to the total travel time;
a reflection point identifying means for identifying a reflection point at the buried object in accordance with the superimposed amplitude;
having
Identifying a shape of the buried object from a plurality of reflection points calculated from the waveform data obtained by exciting the vibration device at a plurality of different positions ;
the total travel time calculation means calculates the total travel time of the elastic waves from the excitation point of the excitation device to one of the receiving points among the points via underground scattering points set at intervals smaller than the size of the buried object;
The amplitude superimposition means superimposes the amplitude of the waveform data at the one receiving point during the total travel time as the amplitude of the scattering point, and superimposes the amplitude of the scattering point from each receiving point for each scattering point;
An exploration system , characterized in that the reflection point identifying means identifies the reflection point from the scattering points according to the amplitude of the superimposed scattering points .

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