KR100742773B1 - device for measuring velocity of elastic wave and method using it - Google Patents

Abstract

The present invention relates to a seismic velocity measuring device and a measuring method using the same, which is installed at the tip of the penetration equipment to minimize the ground disturbance during penetration and can measure the micro-strain seismic wave, the upper portion to be coupled to the end of the penetration rod that is inserted into the borehole And a spatula-shaped connector having a sharp lower end for easy insertion, a plurality of support bars connected to the connector so as to be inserted therein and extending downward to form a cylindrical shape, and strength of the support bar. And a support ring coupled to an upper portion of the plurality of support bars to maintain a shape, and a plurality of transducers installed up and down on one of the plurality of support bars and an inward surface of the opposite side thereof to transmit and receive an elastic wave; It is coupled to the end of the support bar of the annular having a sharp lower end to minimize the disturbance of the ground when ground penetration As made of an Id shoe, there is an effect that can be tested is possible, and also easily calculated undisturbed (非 攪亂) anisotropy (anisotropy) of the soil at the site, as well as be able to carry the ground investigation in a state in water or soil.

Seismic wave, velocity measurement, restraint modulus, shear modulus

Description

Device for measuring velocity of elastic wave and method using it

1 is a configuration diagram schematically showing the configuration and operation of a conventional downlink seismic detection method.

Figure 2 is a schematic view showing the configuration and operation of the conventional physical acoustic wave logging method widely used in the penetration test is impossible.

Figure 3 is a front view of an embodiment of an acoustic wave velocity measuring apparatus according to the present invention.

Figure 4 is a side cross-sectional view of an embodiment of an acoustic wave velocity measuring apparatus according to the present invention.

Figure 5 is a cut plan view showing the structure of the guide shoe in one embodiment of the present invention.

Figure 6 is a partial cross-sectional view for showing the structure of the guide shoe in an embodiment of the present invention.

Figure 7 is a perspective view of one embodiment of an acoustic wave velocity measuring apparatus according to the present invention.

Figure 8 is a schematic diagram for showing the transmission path of the acoustic wave transmitted and received in the elastic wave velocity measuring apparatus according to an embodiment of the present invention.

9 is a signal flow diagram schematically showing a measuring method using an elastic wave velocity measuring apparatus according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: penetration rod 20: spatula connector

30: support bar 32: wiring cover

40: support ring 50: transducer

60: guide shoe 100: elastic wave velocity measuring device

The present invention relates to a penetrating seismic velocity measuring device and a measuring method using the seismic wave, and more particularly, it is installed on the distal end of the penetrating equipment to minimize the disturbance of the ground during penetration and to measure the seismic wave of the small strain and It relates to a measuring method using the same.

The most important factor in securing the stability of all construction structures is securing the stability of the ground structure. Various ground investigation tests are conducted to secure the stability of the ground. Therefore, in order to evaluate the stability of the ground in various civil constructions, the spatial distribution of the soft ground such as the crushing zone and the analysis of the dynamic characteristics of the ground must be made in advance.

In particular, the importance of basic ground is increasing in IT-related industries where the defect rate rapidly increases even in the case of very small deformations such as semiconductors.

In addition, as the number of earthquakes and the magnitude of earthquakes have increased greatly in recent years, earthquake-resistant design of ground structures has been recognized as important, and ground surveys in micro deformations are one of the most important elements in seismic design.

In the vibration-sensitive structure or the seismic design, the dynamic properties of the ground such as the coin step number (Gd), the dynamic modulus (Ed), and the poisson's ratio (υ) are needed. Can be obtained from field exploration tests or from dynamic laboratory tests on field Buddhism eggs samples. The field test of the above test methods has the advantage that the results are relatively high and can be performed relatively quickly because they are less influenced by the disturbance of the ground or the change of the stress state than the indoor tests on the collected samples. .

In the field survey test, a method such as a downhole seismic survey method or a borehole logging method or an acoustic logging method capable of measuring seismic waves in a micro strain is performed. The above exploration methods will be described in detail as follows.

First, in the downhole seismic survey method as shown in FIG. 1, the transmitter 4 of the acoustic wave is located on the ground and the receiver 5 is provided at the tip of the penetration device 3. That is, when the elastic wave 6 transmitted from the ground surface 2 propagates below the ground surface, the elastic wave 6 is measured by the receiver 5 at the distal end, and the length Δz between the receivers 5 and the receiver 5 are measured. The elastic wave velocity V of the ground 1 is calculated from the elastic wave measurement time difference Δt using the following equation (1).

However, when the downlink seismic survey is performed in water rather than on land, the shear wave does not propagate at all in a liquid such as water.

In addition, the physical acoustic wave logging method (borehole logging or Acoustic logging methods) widely used in places where penetration testing is not possible as shown in Figure 2 can calculate the seismic wave in the rock. This is an on-site exploration test method for the borehole (7) by inserting a probe (8) in which the transmitter (9) and the receiver (5) are integrated into the borehole (7) and the transmitter in the borehole (7) (9) and receiver (5) are used to obtain and propagate the propagation speeds for two kinds of elastic waves (P) (primary wave) and secondary wave (S) (Secondary wave) for each layer. A technique to investigate the physical properties of The two kinds of acoustic waves refer to P waves and S waves, which are called longitudinal waves or small waves, and are waves that propagate while oscillating in the direction of wave propagation, and S waves are transverse waves, which propagate while oscillating in the wave propagation direction.

By using the seismic velocities (Vp, Vs) as a result of the velocity logging, dynamic elastic constants (such as poisson's ratio, coin step number, dynamic coefficient and Dynamic elastic modulus) can be calculated, and it is also possible to grasp the attenuation characteristics of the elastic waves Vp and Vs in the ground from the measured waveform recording. In addition, the velocity values of the P and S waves obtained from the logging results reflect various geological and mechanical characteristics of the rock and can be used for estimation of the geologic structure, including weathering zone, weakness determination, and strata classification, along with other logging results. .

However, the above method has a problem in that the acoustic wave calculated by the guidely tube or the like when the test is performed on clay or sandy ground appears to be irrational at all, so that the application of the acoustic wave logging is impossible.

The present invention is to solve the above problems, the object of the present invention is to overcome the disadvantages of the downhole seismic survey and the disadvantages of the borehole logging methods or acoustic logging methods as described above In addition, it is possible to test on the ground, and to perform the ground survey in a non-random state, and to easily calculate the anisotropy of the soil in the field, and the apparatus for measuring the acoustic wave velocity It is to provide a measuring method used.

In order to achieve the above object, the elastic wave velocity measuring apparatus of the present invention comprises: a spatula-type connector having a coupling portion at an upper portion to be coupled to an end of a penetration rod introduced into a borehole, and having a sharp lower end portion for easy penetration;

A plurality of support bars connected to the connector and extending downward to form a cylindrical shape so that a sample can be charged therein;

A support ring coupled to an upper portion of the plurality of support bars to maintain the shape of the support bars;

A plurality of transducers vertically installed on one side of the plurality of support bars and the inward surface of the side opposite to the plurality of support bars to transmit and receive an elastic wave; And

An annular guide shoe coupled to an end of the support bar and having a sharp lower end portion to minimize disturbance of the ground during ground penetration; Characterized in that consists of.

It is preferable that a wiring cover is attached to an outer surface of the support bar on which the transducer is installed to prevent exposure of the wire connected to the transducer.

It is preferable that the spatula-type connector has a wider width and a thinner thickness from the top to the bottom thereof, thereby forming a spatula shape having a sharp blade shape.

The plurality of transducers are preferably installed up and down on the inward surface of any one of the plurality of support bars and the inward surface of the support bar opposite thereto, and the transmission and reception between the opposing transducers is the same height. It is also preferred to be between different heights.

The annular guide shoe has a round annular shape, and ends of the plurality of support bars are coupled to an upper surface thereof, and the lower part is sharply formed like a blade so as to minimize resistance and disturbance of the ground when penetrated into the ground. desirable.

In addition, the elastic wave speed measuring method of the present invention, the first step of coupling the elastic wave speed measuring apparatus of the present invention to the penetration bar and injecting the combined penetration bar into the ground;

A second step of calculating an arrival time (t) by transmitting an elastic wave in one of a plurality of transducers and receiving the signal from a transducer installed at an opposite position;

A third step of calculating the velocity (Vp, Vs) of the acoustic wave by using the arrival time t and the distance L between the transducers according to Equation 2 below; And

A fourth step of calculating soil constants (M, G) of the ground by using Equations 3 and 4 using the elastic wave velocities (Vp, Vs) and calculating anisotropy; Characterized in that consists of.

Where L is the distance between the transmitter and receiver, t is the arrival time of the seismic wave, V is the velocity of the seismic wave, Vp is the compressed wave velocity, M is the constrained modulus of elasticity, ρ is the ground density, Vs is the shear wave velocity, and G is the shear Modulus of elasticity. Here, Equation 2 shows a general formula for obtaining the velocity of the acoustic wave. When the elastic wave calculated using Equation 2 is a compressed file, the constraint elastic modulus M can be obtained using Equation 3, and when the elastic wave calculated using Equation 2 is a shear file, Equation 4 Shear modulus (G) can be obtained by using.

In the third step, the speed in the horizontal direction may be calculated using the distance and time between the transducers that are horizontally opposed.

In the third step, the speed in the oblique direction may be calculated using the distance and time between the lower transducer on one side and the upper transducer on the opposite side or by using the distance and time between the upper transducer on the one side and the lower transducer on the opposite side. Can be.

Hereinafter, a configuration according to an embodiment of an elastic wave velocity measuring apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

Figure 3 is a front view of an embodiment of the elastic wave speed measuring apparatus according to the present invention, Figure 4 is a side cross-sectional view of an embodiment of the elastic wave speed measuring apparatus according to the present invention, Figure 5 is an embodiment of the present invention 6 is a cross-sectional view for showing the structure of the guide shoe, Figure 6 is a partial cross-sectional view for showing the structure of the guide shoe in one embodiment of the present invention.

And, Figure 7 is a perspective view of an embodiment of the elastic wave speed measuring apparatus according to the present invention, Figure 8 is a schematic diagram for showing the transmission path of the elastic wave transmitted and received in the elastic wave speed measuring apparatus according to an embodiment of the present invention. 9 is a signal flow diagram schematically showing a measuring method using an acoustic wave velocity measuring apparatus according to an embodiment of the present invention.

As shown in Figure 3 to Figure 7, the elastic wave velocity measuring apparatus according to an embodiment of the present invention, the connection portion 22 is provided at the upper portion to be coupled to the end 12 of the penetration rod 10 introduced into the borehole And a spatula-type connector 20 having a sharp lower end 24 for easy penetration, and a plurality of support bars connected to the connector 20 so as to be inserted therein and extending downward to form a cylindrical shape. 30, a support ring 40 coupled to an upper portion of the support bar 30 to maintain the shape of the support bar 30, and one side of the plurality of support bars 30 and the side opposite thereto. Installed on the inward surface of the plurality of transducers 50 for transmitting and receiving elastic waves, and coupled to the end of the support bar 30 and having a sharp lower end 62 to minimize the disturbance of the ground during penetration; It consists of an annular guide shoe 60.

3 and 7, a wire cover 32 is attached to an outer surface of the support bar 30 on which the transducer 50 is installed to supply a current connected to the transducer 50. Prevents exposure of wires for seismic signal transmission.

The spatula-type connector 20 has a wider width and a thinner thickness as it goes down from the top to a spatula shape having a sharp blade shape at the bottom thereof, and has a connection portion 22 with the penetration bar 10 at the top thereof. It is coupled to the end 12 of the penetration rod 10 is inserted into the borehole. The coupling may be coupled to one side having a bolt portion and the other side having a nut portion.

The spatula-type connector 20 has a sharp lower end portion 24 so that the elastic wave velocity measuring device of the present invention can be easily penetrated by reducing resistance when penetrating into the ground.

The plurality of support bars 30 are connected to the outer surface of the connector 20 and extend downward to form a cylindrical shape. The connection may be fixed by welding or by bolting.

Here, the reason for adopting a plurality of support bars 30 without using a cylinder for the portion where the sample is loaded is to reduce the disturbance of the sample generated when the sample is loaded into the inside, and to transmit and receive the elastic wave from the transducer. This is to prevent the stonely wave caused by the direct transmission through the wall.

The support ring 40 of the support bar 30 to maintain the strength to be able to penetrate the elastic wave velocity measuring apparatus 100 of the present invention into the ground and to maintain the cylindrical shape of the support bar 30 constant Coupled to the top. The coupling may use welding or bolting.

As can be seen in FIG. 8, the plurality of transducers 50 are vertically disposed on an inward surface of one of the plurality of support bars 30 and an inward surface of the side opposite to the support bar 30. It is installed to transmit and receive elastic waves. The transducer 50 transmits an elastic wave at one side and receives the other at the opposite side. Transmission and reception between the opposing transducers 50 is performed between different heights as well as the same height.

Transducer 50 for transmitting and receiving the elastic wave is installed on the short path as described above, it is possible to derive the elastic wave velocity without the occurrence of errors in the transmission and reception of the elastic wave due to obstacles present in the field ground, from which various soil constants (M, G) ), As well as anisotropy of the ground. Where M is the constraint modulus of elasticity and G is the shear modulus of elasticity.

The anisotropy occurs because the characteristics of the horizontal and inclined directions of the ground are different, and in order to evaluate the anisotropy, it is necessary to obtain not only the horizontal speed but also the inclined direction of the sample.

In addition, as can be seen from Figure 5 and Figure 6, the annular guide shoe 60 has a round annular shape and is coupled to the end of the plurality of support bar 30, the coupling is to the welding or bolting You can.

The lower end 62 of the guide shoe 60 is sharply formed like a blade to minimize the resistance and disturbance of the ground when the elastic wave velocity measuring device according to the present invention is introduced into the ground.

The elastic wave velocity measuring method using the elastic wave velocity measuring apparatus according to an embodiment of the present invention configured as described above will be described in detail with reference to the accompanying drawings.

As shown in FIG. 9, in the method of measuring elastic wave speed according to an exemplary embodiment of the present invention, the elastic wave speed measuring apparatus 100 of the present invention is coupled to a penetration bar 10, and the coupled penetration bar 10 is grounded. A first step (S1) of intruding therein and a second step of transmitting an acoustic wave in one of the plurality of transducers 50 and receiving the signal from the transducer 50 installed at the opposite position to calculate the arrival time t A third step S3 of calculating the speeds Vp and Vs of the acoustic wave by using Equation 2 using step S2 and the distance L between the arrival time t and the transducer 50; And a fourth step (S4) of calculating soil anisotropy and calculating soil constants (M, G) by using Equations 3 and 4 using the seismic velocities Vp and Vs. .

This will be described in more detail as follows.

First, the elastic wave speed measuring apparatus 100 of the present invention is coupled to the penetration bar 10 and the combined device is introduced into the ground (S1). That is, the device is introduced to the required depth by using a penetration device on the ground or in the water.

Next, select one of the transducers 50 arranged as a transmitter to select an input wave such as an impulse wave, a sinusoidal wave, or a square wave from the ground or the water. After sending, receive and measure the signal from the opposite transducer 50 installed. That is, the time of arrival by transmitting the acoustic wave from the transducer 50 selected from the one installed on one side of the support bar 30 and receiving the acoustic wave signal from the transducers 50 installed on the support bar 30 in the opposite position. (t) is calculated (S2). The acoustic wave includes a compression wave and a shear wave, so that the arrival time of each wave can be measured separately.

Next, the speeds Vp and Vs of the elastic waves are calculated by using Equation 2 using the distance L between the arrival time t and the transducer 50 through which the elastic waves are transmitted and received (S3). Where L is the distance between the transmitter and receiver, t is the arrival time of the acoustic wave, and V is the velocity of the acoustic wave.

As can be seen in Figure 8, the speed in the horizontal direction can be calculated using the distance between the transducers 50 facing horizontally, the speed in the inclined direction is the lower transducer 50 on one side of the opposite side The distance and time between the upper transducers 50 may be calculated using the distance and time between the upper transducer 50 on one side and the lower transducer 50 on the opposite side. That is, the signal transmitted from the same transmitter using a transducer 50 installed at a different position and then receiving a signal, the distance (L) between the transmitting transducer 50 and the receiving transducer 50 and the elastic wave The speed in the inclination direction can be easily calculated from the arrival time t. However, signals transmitted and received between the upper and lower transducers 50 installed on the same support bar 30 may not be used due to the influence of the stonely wave.

Finally, the soil constants (G, M) of the ground are calculated using the equations (3) and (4) by using the elastic wave speeds (Vp, Vs) in the horizontal direction, and the elastic wave speeds (Vp, Vs) in the slope direction. Soil soil constants (G, M) of the ground in the inclined direction can be calculated using Equation 3 and Equation (4), and the elastic wave speeds (Vp, Vs) in the horizontal direction and the elastic wave speeds (Vp) in the slope direction , Vs) to calculate the anisotropy of the ground (S4). Where Vp is the compressed wave velocity, Vs is the shear wave velocity, M is the constraint modulus of elasticity, G is the shear modulus of elasticity, and ρ is the density of the ground.

delete

According to the elastic wave velocity measuring apparatus and the measuring method according to an embodiment of the present invention as described above, it is possible to test in the water or the ground and to perform the ground survey in the non-random state as well as the field The anisotropy of the soil can also be easily calculated.

Claims (9)

A spatula-type connector having a coupling portion at an upper portion to be coupled to an end of a penetration rod introduced into a borehole, and having a sharp lower portion to facilitate penetration; A plurality of support bars connected to the connector and extending downward to form a cylindrical shape so that a sample can be charged therein; A support ring coupled to an upper portion of the plurality of support bars to maintain the strength and shape of the support bars; A plurality of transducers vertically installed on one side of the plurality of support bars and the inward surface of the side opposite to the plurality of support bars to transmit and receive an elastic wave; And An annular guide shoe coupled to an end of the support bar and having a sharp lower end portion to minimize disturbance of the ground during ground penetration; Elastic wave velocity measurement apparatus, characterized in that consisting of. The apparatus of claim 1, wherein a wire cover is attached to an outer surface of the support bar on which the transducer is installed to prevent exposure of wires connected to the transducer. The apparatus of claim 1, wherein the spatula-type connector becomes wider and thinner from the top to the bottom to form a spatula having a sharp blade. The apparatus of claim 1, wherein the plurality of transducers are disposed up and down on an inward surface of one of the plurality of support bars and an inward surface of a support bar opposite thereto. The apparatus of claim 1 or 4, wherein transmission and reception between the opposing transducers are performed not only at the same height but also at different heights. According to claim 1, The annular guide shoe has a round annular shape and the end of the plurality of support bar is coupled to the upper surface, the lower portion is like a blade so as to minimize ground resistance and disturbance when intruding into the ground Elastic wave velocity measuring device, characterized in that formed sharply. A first step of coupling the elastic wave speed measuring apparatus of claim 1 to the penetration rod and injecting the combined penetration rod into the ground; A second step of calculating an arrival time (t) by transmitting an elastic wave in one of a plurality of transducers and receiving the signal from a transducer installed at an opposite position; A third step of calculating the speeds Vp and Vs of the acoustic wave by using the arrival time t and the distance L between the transducers according to Equation 1 below; And A fourth step of calculating soil constants (M, G) of the ground by using Equations 2 and 3 using the elastic wave velocities (Vp, Vs) and calculating anisotropy; Elastic wave velocity measurement method, characterized in that consisting of. [Equation 1]

[Equation 2]

[Equation 3]

Where L is the distance between the transmitter and receiver, t is the arrival time of the seismic wave, V is the velocity of the seismic wave, Vp is the compressed wave velocity, Vs is the shear wave velocity, M is the constraint modulus, G is the shear modulus, The density of the ground) 8. The method of claim 7, wherein the horizontal speed is calculated using the distance and time between the transducers facing each other horizontally in the third step. 8. The method of claim 7, wherein the speed in the inclined direction in the third step uses a distance and time between the lower transducer on one side and the upper transducer on the opposite side or the distance between the upper transducer on the one side and the lower transducer on the opposite side. Method for measuring the acoustic wave, characterized in that for calculating and selecting any one of using and time.

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