JP3665821B2 - High-density three-dimensional reflection seismic survey equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-density three-dimensional reflection seismic exploration apparatus, and more particularly to an apparatus suitable for high-density three-dimensional exploration of geological structures such as roads, parking lots, and asphalt-paved embankment slopes.
[0002]
[Prior art]
As one of the conventional underground exploration techniques, a three-dimensional reflection seismic exploration technique is known. This technique is a two-dimensional reflection seismic exploration technique that has been widely used in resource exploration techniques, and is a method that enables three-dimensional exploration of underground geological structures. In this three-dimensional reflection seismic survey, a large number of oscillation points and receiving points are arranged in a plane, and signals from all directions are observed and processed to reconstruct a three-dimensional structure.
[0003]
In the conventional seismic exploration method, the vibration sensor is cheaper than the oscillation device, and it takes time to move and oscillate the oscillation device. In comparison, a method of acquiring signals from a relatively small number of oscillation points has been common.
However, with this conventional method, it takes a long time to install a large number of vibration receiving sensors on the ground surface, and such work cannot be shortened.
In urban areas, most of the surface of the earth is paved with asphalt or covered with solidified bodies, so the method of fixing the vibration sensor used in conventional seismic reflection surveys with spikes is applied. There was also a problem that it was not possible.
[0004]
In the two-dimensional reflection seismic exploration technique, a device is known in which a plurality of vibration receiving sensors are suspended on a straight line and moved by a wheeled device (see Japanese Patent Application Laid-Open No. 7-301677). Can only be used for two-dimensional reflection seismic exploration because the vibration sensors are only arranged in a line, and it is necessary to ground the vibration sensor during measurement. Furthermore, since only the vibration sensor is attached, there is a problem that the oscillation device must be separately installed while moving.
[0005]
On the other hand, if “land streamer exploration technology” is applied to land where the 3D multi-channel sound wave exploration method implemented in the sea area is used, the work time required for installation of the above-mentioned vibration sensor can be significantly reduced. it can. However, this technology requires special maintenance parts to keep the distance between the plurality of land streamers constant. In addition, since the position of the oscillation point is limited to the front and back of several land streamers that are developed substantially in a plane, it is necessary to guarantee signal observation from all directions, which is indispensable for the reconstruction of a three-dimensional underground structure with high accuracy. I could not.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described problems, and eliminates the need to install an oscillation device and a vibration receiving sensor each time measurement is performed, and enables high-density three-dimensional exploration of underground geological structures at high density. The object is to provide a density three-dimensional seismic reflection survey device. In particular, an object of the present invention is to provide a device suitable for high-density three-dimensional exploration of a shallow geological structure under a paved surface such as a road, a parking lot, and an asphalt-paved embankment slope.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the high-density three-dimensional reflection seismic survey apparatus of the present invention arranges an oscillation point and a receiving point in a plane, and observes and processes signals from all directions, thereby obtaining a tertiary structure. A three-dimensional reflection seismic exploration device that is originally explored is characterized in that a plurality of oscillation devices and vibration receiving devices are mounted on a non-stretchable planar member.
The high-density three-dimensional reflection seismic survey apparatus of the present invention is characterized in that the non-stretchable planar member is formed from a non-stretchable sheet, mesh, net or non-woven fabric.
In the high-density three-dimensional reflection seismic survey apparatus according to the present invention, a plurality of rows of vibration receiving lines are arranged in a horizontal direction at equal intervals on a planar member, and a plurality of vibration receiving lines in each row are arranged at equal intervals. A vibration receiving device is mounted so as to have a channel configuration.
The high-density three-dimensional reflection seismic survey apparatus of the present invention is characterized in that an oscillation device is mounted on a planar member so as to surround the vibration receiving device.
The high-density three-dimensional reflection seismic survey apparatus of the present invention is characterized in that the interval between the receiving line and the oscillation line is the same as the receiving point interval or an integer multiple thereof.
The high-density three-dimensional reflection seismic survey apparatus of the present invention is characterized in that a rod is attached to one end surface of the planar member, and a traction means is attached to the rod.
The high-density three-dimensional reflection seismic survey apparatus according to the present invention has a base plate disposed on the lower surface of the planar member and a mating panel on the upper surface, and these members are tightly integrated with screws or the like. The vibration receiving device is configured by arranging a vibration receiving sensor on the upper surface of the plate and fixing the vibration receiving sensor to a base plate.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view showing the overall configuration of a three-dimensional reflection seismic survey apparatus according to an embodiment of the present invention.
Reference numeral 1 denotes a non-stretchable planar member, which is made of, for example, a non-stretchable sheet, a non-stretchable mesh, a net, or a non-woven fabric. As the material, for example, vinyl acetate, canvas, acrylic resin, or the like may be used as long as it is non-stretchable and has a strength capable of withstanding a load during movement. Note that a metal plate that easily transmits vibration is not suitable.
On the planar member 1, four rows of receiving lines 5, 5, 5, 5 are arranged in the horizontal direction at equal intervals a, and the receiving lines 5 in each row have 12 channels at intervals a. As shown, twelve receiving points 2 are set. A vibration receiving device 20 is installed at each vibration receiving point as described later.
[0009]
The oscillation line 6 is circulated so as to surround the four rows of receiving lines 5, 5, 5, 5, and a total of 40 oscillation points 3 are arranged on the oscillation line 6 at the same interval as the receiving point interval a. Although the total number of oscillation points 3 is 40 here, the total number may be increased or decreased depending on the number of receiving lines 5 and the required resolution. In short, it is important to arrange the oscillation point 3 on one planar member 1 so as to surround the receiving point 2. The interval between the receiving line 5 and the oscillating line 6 is basically the same as the receiving point interval a, but may be an integer multiple according to the target depth. As will be described later, an oscillation device is installed at each oscillation point.
[0010]
The planar member 1 provided with a series of vibration receiving devices and oscillation devices makes it possible to move the whole while maintaining the relative positional relationship between the vibration receiving devices and the oscillation devices, that is, the distance a. Therefore, the rod 4 is attached to one end surface of the planar member 1. In FIG. 1, the rod 4 is mounted over the entire length of one end face parallel to the vibration receiving line 5. The rod 4 is provided with an intermediate rod 8 and a traction rod 9 via a traction rope 7. As shown in FIG. 1, the intermediate rod 8 and the traction rod 9 are gradually shortened, and are arranged so that the central portion of the traction rod 9 is positioned at the center of the planar member 1. When towed, the traction force is not unevenly distributed. Moreover, even if the rod 4 is elastically deformed by adjusting the suspension position or the number of the pulling ropes 7 attached to the rod 4, the planar member 1 can be pulled without being bent. The traction means can be provided on both sides of the planar member 1. Moreover, it can replace with a tow rope and can also use a well-known link member.
[0011]
The receiving point 2 interval a is a value that depends on the target depth of the three-dimensional exploration using this device, but considering the operability of the entire device and the certainty of the function of maintaining the plane, the distance from 20 cm to 1 m It becomes a standard. Therefore, the size of the planar member 1 is about 3.6 m × 1.8 m at the minimum and about 18 m × 9 m at the maximum.
[0012]
When the receiving point 2 interval a is set to about 20 cm to 50 cm, the maximum receiving point-oscillation point distance (maximum offset distance) is about 2.8 m to 7 m, and a sufficient signal can be obtained even with a small oscillation energy. Distance.
In this case, hammer striking means is sufficient as the oscillating means, and therefore it is only necessary to install a striking board at the oscillation point 3. The striking board installed at the oscillation point 3 is made of metal, and any material can be used as long as it has resistance to hammering and has conductivity. These striking boards are connected to each other by a trigger wire 12 and are connected to a data recording device (not shown) via a control box 11. By connecting a trigger wire to the hammer and joining it to the data recording device, it becomes possible to synchronize the timing of the moment of hitting with the hammer.
[0013]
When the receiving point 2 interval a is set to 50 cm or more, depending on the ground conditions, there is a possibility that a sufficient elastic wave signal cannot be obtained by hammering. In this case, a solenoid type oscillation device is installed at the oscillation point 3. The oscillation device at each oscillation point 3 is driven via the control box 11 and the control signal is transferred to the data recording device via the trigger line 12.
[0014]
2 and 3 show the structure of the vibration receiving device 20 at the vibration receiving point 2. FIG. 2 is a plan view and FIG. 3 is a cross-sectional view taken along line AA of FIG.
The vibration receiving sensor 13 is installed unfixed to the pavement surface 19 via the base plate 14 so as to be movable with respect to the pavement surface 19. Since non-fixed installation is disadvantageous for obtaining a good signal, in this embodiment, the bottom surface of the base plate 14 is smooth and the installation area is large so that high-quality data can be obtained as much as possible. Designed to take. The thickness of the base plate 14 is also set to an appropriate value so as not to become unstable during towing in consideration of the coupling between the paved surface 19 and the vibration receiving sensor 13. Further, in consideration of the fact that the weight of the base plate 14 greatly affects the coupling between the pavement surface 19 and the vibration receiving sensor 13 and does not become overloaded during towing, the weight is set to about 200 g to 500 g in the present embodiment. The material of the base plate 14 is not particularly limited as long as it satisfies the above conditions. Preferably, aluminum or stainless steel is most suitable considering that it is easy to process and does not rust.
[0015]
Since the vibration receiving sensor 13 is loaded during movement, it is important to firmly fix the vibration receiving sensor 13 so as not to shift its position on the planar member 1. However, in general, the sheets constituting the planar member are easy to split and break, so the surface is designed to have a load. That is, the planar member 1 is sandwiched between the base plate 14 and the laminating board 15, and the fastening screw 16 is tightened to unify the base plate 14 and the vibration receiving sensor 13, and to be crimped and fixed to the planar member 1. Further, the vibration receiving sensor 13 itself is fixed to the base plate 14 with a fastening screw 17 for integration. When power supply to the vibration receiving sensor 13 is necessary, power supply and signal transfer from the vibration receiving sensor 13 are performed by connecting the extraction line 18 to the signal line 21 configuring the vibration receiving line 5. The signal line 21 is connected to the signal transmission line 10 via the junction box 22.
[0016]
FIG. 4 is an explanatory diagram showing a state in which an underground geological structure is investigated while moving the above-described high-density three-dimensional reflection seismic survey device.
When the oscillation device is activated, the elastic wave 23 is reflected by the reflection point 24 and received by the vibration receiving device 20, and transferred to the data recording device (not shown) via the signal transmission line 10.
At this time, when the measurement at one oscillation point is completed, as shown in FIG. 4, the planar member 1 on which the oscillation device and the reception device 20 are mounted is moved by a certain distance, and the measurement is repeated with overlapping measurement lines. Is taken. If the receiving point 2 interval a is reduced, the density of the reflection points 24 is increased and the spatial resolution in the horizontal direction is improved, so that detailed structural analysis is possible. Also, good data cannot be acquired if the approach angle of the elastic wave 23 becomes an obtuse angle with respect to the reflection point 24. Therefore, when investigating the shallow layer, it is necessary to reduce the distance between the oscillation point and the receiving point.
[0017]
According to the high-density three-dimensional reflection seismic survey apparatus according to the present embodiment, a large number of pseudo vibrations are received on the ground surface by moving while maintaining the relative positional relationship between the vibration receiving point 2 and the oscillation point 3. It becomes possible to arrange the points. In other words, in the conventional 3D seismic survey, a large number of receiving points are arranged on the ground surface in advance, but in the high density 3D reflection seismic survey apparatus according to the present embodiment, a small number of receiving points and oscillation points are moved. It is possible to achieve the same function.
In addition, the conventional three-dimensional seismic survey includes a large number of positions with a large receiving point-oscillation point distance, whereas the high-density three-dimensional reflection seismic surveying device according to the present embodiment The maximum point-oscillation point distance is about 14a, which enables high-density seismic exploration and has the advantage of being able to maintain an arrangement suitable for shallow exploration.
[0018]
In the high-density three-dimensional reflection seismic survey apparatus according to the present embodiment, when the receiving point interval a is set to 20 cm, the total weight is about 50 kg and can be sufficiently moved even by human power. Further, in the case of hammering, the oscillation operation can be executed in a few seconds including the movement to the next point, and the maximum 40-point oscillation shown in FIG. 1 requires only about 2 minutes.
Therefore, it is estimated that a three-dimensional ground structure having a width of 2.4 m and a length of about 20 m can be reconstructed with a resolution of 10 cm intervals (24 × 200) in one hour of work.
In the case of P-wave oscillation, the target depth is estimated to be approximately 5 m below the paved roadbed, although it depends on the speed of the ground, and the resolution in the depth direction is estimated to be about several centimeters. These values are sufficient for structural investigation under the pavement surface, and particularly, it is possible to search an area with a depth of 2 m or more, which has been considered difficult to search by a ground penetrating radar.
[0019]
Here, an example is shown in which each row of receiving lines 5 is composed of 4 rows and each line is composed of 12 channels. However, the number of receiving lines 5 and the number of constituent lines, that is, the number of receiving points 2 are determined according to the required resolution. You may increase or decrease. In short, it is important to arrange the receiving points 2 and the receiving lines 5 composed of the receiving points 2 at equal intervals on one planar member 1.
[0020]
【The invention's effect】
As described above, the present invention has the following effects. (1) By arranging the receiving point and the oscillation point in a planar shape, the underground geological structure can be explored three-dimensionally.
(2) By mounting the vibration receiving device and the vibration receiving device on the planar member, the operation of installing the vibration receiving device and the vibration receiving device for each measurement becomes unnecessary, and the device can be easily moved. Therefore, the exploration work can be efficiently performed in a short time even on the pavement surface.
(3) Since the movement is performed while maintaining the relative positional relationship between the receiving point and the oscillating point, a large number of pseudo receiving points can be arranged on the ground surface.
(4) Since the receiving point interval can be reduced, the spatial resolution in the horizontal direction is improved and a detailed structural analysis is possible.
(5) Since the distance between the oscillation point and the receiving point can be reduced, high-density seismic exploration is possible, and a device suitable for exploration of shallow layers can be provided.
(6) Since the entire device is lightweight, it is possible to move the device manually and to measure a place where the vehicle cannot enter.
(7) Since the distance between the oscillation point and the receiving point is short, the oscillation device can be downsized.
(8) Since the planar member on which the vibration receiving device and the oscillation device are mounted can be formed of a non-stretchable sheet, the device can be reduced in weight and cost.
[Brief description of the drawings]
FIG. 1 is a plan view showing an overall configuration of a three-dimensional reflection seismic survey apparatus according to an embodiment of the present invention.
FIG. 2 is a plan view showing the structure of the vibration receiving device according to the embodiment of the present invention.
3 shows the structure of the vibration receiving device according to the embodiment of the present invention, and is a cross-sectional view taken along line AA in FIG. 2. FIG. 4 is a high-density three-dimensional reflection seismic survey according to the embodiment of the present invention. It is explanatory drawing which showed the state which investigates an underground geological structure, moving an apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Planar member 2 Receiving point 3 Oscillating point 4 Rod 5 Receiving line (Linear arrangement comprised of receiving point 2 and signal line 21)
6 Oscillation line (Linear arrangement consisting of oscillation point 3 and trigger line 12)
7 Tow rope 8 Intermediate rod 9 Tow rod 10 Signal transmission line 11 Control box 12 Trigger line 13 Vibration sensor 14 Base plate 15 Laminating panel 16, 17 Set screw 18 Lead line 19 Pavement surface 20 Vibration receiving device 21 Signal line 23 Elastic wave 24 Reflection point

Claims (5)

  In a three-dimensional reflection seismic exploration device that three-dimensionally explores geological structures by locating oscillation points and receiving points in a plane, and observing and processing signals from all directions, a non-stretchable surface On the member, a plurality of rows of vibration receiving lines are arranged in the horizontal direction, and a vibration receiving device is mounted on each row of vibration receiving lines so as to have a configuration of a plurality of channels, and an oscillation line is arranged so as to surround the vibration receiving lines. A plurality of oscillation devices are attached to the oscillation line, and a vibration receiving device on one planar member is attached by attaching a rod with a traction means to one end face parallel to the vibration receiving line of the planar member. A high-density three-dimensional reflection seismic survey device characterized in that it can move while maintaining the relative positional relationship between the oscillating device and the oscillation device.   2. The high-density three-dimensional reflection seismic survey apparatus according to claim 1, wherein the planar member is formed of a non-stretchable sheet, mesh, net or non-woven fabric.   3. A high-density three-dimensional reflection earthquake according to claim 1 or 2, wherein a plurality of rows of receiving lines are arranged at equal intervals in the horizontal direction, and receiving devices for the receiving lines of each row are mounted at equal intervals. Exploration device.   4. The high-density three-dimensional structure according to claim 1, wherein an interval between the receiving line and the oscillating line is the same as the receiving point interval or an integral multiple of the receiving point interval. 5. Reflection seismic survey equipment.   A base plate is placed on the lower surface of the planar member, and a mating board is placed on the upper face. These members are tightly integrated with screws, etc., and a vibration sensor is placed on the upper surface of the mating board. The high-density three-dimensional reflection seismic survey apparatus according to any one of claims 1 to 4, wherein the vibration receiving device is configured by being fixed.

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