JPH02157681A - Underground surveying method for shield method - Google Patents

Abstract

PURPOSE:To accurately and easily made a survey by sending a P wave, an S wave, and a Rayleigh wave into the ground from oscillators for the P wave, S wave, and Rayleigh wave which are provided on the front surface plate of a shield main body. CONSTITUTION:The vibration generator (oscillator) 5 which generates the Rayleigh wave B (surface wave) is provided nearby the center of the surface plate 2a of a cutter head 2 and at least two hydrophones 6 which detect the underground transmitted wave of the Rayleigh wave generated by the vibration generator are provided nearby the vibration generator 5 at a specific mutual distance. The Rayleigh wave which is sent into the ground from the vibration generator 5 reaches the closer hydrophone 6 first and then the farther hydrophone 6B. For the purpose, the Rayleigh wave detection time difference between the hydrophones 6A and 6B is measured to calculate the Rayleigh wave speed, and consequently the soil structure, obstacle, cavity, etc., of the front ground are investigated.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an underground exploration method in the shield construction method.

If an obstacle such as a huge buried object is encountered while excavating a tunnel using conventional shield technology, it will have a large impact on safety and the process. Previously, to avoid this, exploration was conducted from the ground, such as by polling the planned tunnel route. However, this ground-based exploration method is difficult to apply to submarine tunnels and deep tunnels. Therefore,
Currently, a method of exploring the front of the shield body using electromagnetic waves has been proposed.

Problems to be Solved by the Invention In the above-mentioned exploration method using electromagnetic waves, the exploration distance is 2 to 3 meters.
, and the exploration distance becomes even smaller in ground saturated with salt water. As a result, the discovery of obstacles is delayed, and obstacles
There is a problem in that sufficient distance is not guaranteed to safely carry out the work of removing objects.

Therefore, an object of the present invention is to provide an underground exploration method using the shield construction method that can solve the above problems.

Means for Solving the Problems In order to solve the above problems, the underground exploration method in the shield construction method of the present invention is designed to emit P waves, S waves, and Rayleigh waves from an oscillator for P waves, S waves, and Rayleigh waves provided on the front surface of the shield body. In addition to emitting waves and Rayleigh waves underground,
This is a method in which the reflected waves of P and S waves and the transmitted waves of Rayleigh waves are detected by detectors installed on the above-mentioned face plate, and based on these detection data, underground obstacles, soil changes, etc. are detected. be.

Effect According to the underground exploration method described above, if there are obstacles, cavities, or soil boundaries in the ground in front of the shield body,
By comprehensive analysis of P waves, S waves, and Rayleigh waves, they can be detected accurately and easily from about 10 meters ahead in a short time.

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

First, the shield excavator used in the shield construction method will be explained. In the drawings, reference numeral 1 denotes a shield body, and a cutter head 2 is rotatably provided at the front end of the shield body.

A P wave (
Piezoelectric element (oscillator) that generates longitudinal waves) and S waves (transverse waves)
At least one hydrophone 3 is provided, and a plurality of hydrophones (detectors) 4 that capture and detect reflected waves of P waves and S waves oscillated from the piezoelectric element 3 are provided. When a large number of piezoelectric elements 3 and hydrophones 4 are provided, they are arranged in a plurality of rows in the radial direction of the drawing board 2a from near the center outward. The P waves and S waves emitted from the piezoelectric element 3 toward another mountain hit, for example, an obstacle A in the mountain ahead, and the reflected waves are detected by a plurality of hydrophones 4 and reflected at different positions. By measuring the arrival time of the waves, the position of the obstacle A can be determined. Note that P waves are used for short-distance exploration and have high resolution, and S waves are used for long-distance exploration. Furthermore, near the center of the face plate 2a of the cutter head 2, there is provided a hoist (oscillator) 5 that generates a Rayleigh wave (surface wave) B. At least two hydrophones (an example of a detector, and a seismometer may be used) 6 are provided, which are separated by a distance and detect the propagation of Rayleigh waves generated from the hoist 5 within the ground.

The Rayleigh waves emitted into the ground from the hoist 5 first reach the closer hydropon 6A, and then reach the farthest hydropon 6B. Therefore, by measuring the detection time difference between the Rayleigh waves of both hydrophones 6A and 6B, the Rayleigh wave velocity can be calculated, and thereby the soil structure of the ground ahead, the presence or absence of obstacles, cavities, etc. can be determined. Note that the forward reach of this Rayleigh wave changes by increasing or decreasing its frequency. In other words, if the frequency is set high, the nearby soil will be the target of exploration, and if the frequency is set low, the soil at a far location will be the target of exploration. Incidentally, the frequency is changed sequentially according to a preset program. And further.”
- As described above, the detection signal of the reflected wave from each hydrophone 4 and the detection signal of the transmitted wave from each hydrophone 6 are inputted into the inside of the shield body 1 via the controller 7, and these detection signals are A control device that analyzes the distance to the obstacle A or the cavity, its size, and the position of soil change based on predetermined calculations (
For example, a computer (8) consisting of a small electronic computer and a control panel (t11) is arranged. Further, the data analyzed by this control device 8 is sent to a central monitoring and control panel 9 on the ground, and is output as a record and image (for example, one stereoscopic image) to a screen display or to a printer 10.

Next, a method for exploring the underground, that is, the ground in front of the ground will be explained.

The search is performed during segment assembly time.

That is, the P waves and S waves emitted from the piezoelectric element 3 into the local ground are reflected there if there is an obstacle A or a soil boundary within the ground, and the reflected waves are transmitted to the plural hydropons 4. and analyzed by the control device 8. Next, similarly to the above, Rayleigh waves are emitted from the hoist 5 and the Rayleigh wave velocity between the pair of hydrophones 6 is detected.

In this case, the obstacle A in the ground, the cavity, and the soil boundary appear as a boundary layer of Rayleigh wave velocity, and the control device 8
Parsed by.

When the above-mentioned series of investigations are completed in one section, the cutter head 2 is rotated 41 times by a predetermined amount, and the same investigation is repeated to carry out a three-dimensional investigation of the shield main body 1111. In addition, the measured data is stored in a storage device and used as a knowledge database for artificial intelligence that determines whether an object is an obstacle or not.

Note that all of these operations are performed during segment assembly, so there is no impact on the investigation time of the process, and the shield body l will be ready before excavation of the next ring begins.
Since the situation of other mountains in front of the mountain can be investigated and the exploration distance is sufficiently secured, safe cotton weaving is possible.

In this way, by using P waves with high frequency and high resolution, S waves with low frequency and long penetration distance, and Rayleigh waves, which are effective for finding soil boundary layers and cavities from their velocity distribution, obstacles in front of the shield body can be detected. It becomes possible to search up to about 10 meters, and the resolution can be increased to about 30 aa.

Effects of the Invention According to the above-mentioned exploration method of the present invention, if there are obstacles, cavities, or soil boundaries in the ground in front of the shield body, comprehensive analysis of P waves, S waves, and Rayleigh waves can detect them by about 10 m. It is possible to search from the front in a short time, accurately and easily.

[Brief explanation of the drawing]

The drawing is a schematic perspective view showing an embodiment of the exploration method of the present invention. 1... Shield body, 2... Cutter head, 2a.
... Face plate, 3... Piezoelectric element, 4... Hydrophone,
5... Earthquake generator, 6, 6A, 6B... Hydrophone. Agent Yoshihiro Morimoto

Claims (1)

[Claims] 1. Emit P waves, S waves, and Rayleigh waves into the ground from a P wave, S wave, and Rayleigh wave oscillator installed on the face plate on the front of the shield body, and also emit these P waves, S waves, and
A shield construction method characterized by detecting reflected waves of waves and transmitted waves of Rayleigh waves with detectors respectively provided on the face plate, and searching for underground obstacles, soil changes, etc. based on these detected data. underground exploration method.