KR101481074B1 - Measuring system using Dynamic Cone Penetrometer and method for calibrating Transfer Energy thereof - Google Patents

Abstract

(A) a dynamic cone penetrator is dynamically intruded into a ground to be measured, and a controller connected to the dynamic cone penetrator synchronously detects strain and acceleration, Wherein the control unit converts the synchronized strain and acceleration into a load Fs and a particle velocity Va and (C) the control unit calculates the load Fs and the particle velocity Va using the load Fs and the particle velocity Va, And calculating and correcting the energy transferred to the head and the tip of the dynamic cone pipe.

Description

TECHNICAL FIELD The present invention relates to a measurement system using a dynamic cone penetrator and a method of calibrating a transmitted energy using the same,

The present invention relates to a measurement system using a dynamic cone penetrator and a transmission energy correction method using the same.

In general, standard penetration tests and cone penetration tests are widely used as test methods for evaluating the ground stiffness at home and abroad. However, these methods can only be applied to sandy or soft clay grounds. Therefore, when measuring the stiffness of a high-stiff ground such as a mid-soil bed or a rock, it is necessary to measure the stiffness of the ground by drilling a sample of the rock and measuring the core. These ground samples are collected through a penetration test apparatus equipped with a hammer. Generally, in the case of a dynamic penetration apparatus, a hammer is installed on an end portion of a rope wound on a winding drum fixed to a support so that the hammer can be lifted and lowered. The hammer moves up and down a certain path through a guide device. The sampler is coupled to the lower part of the guide device, so that the sampler can be introduced into the ground due to the price of the hammer.

However, in the conventional intrusion apparatus, since the worker has to manually drop the hammer at a predetermined height, there is a problem that the height of the drop of the hammer is uneven even if the operator is skilled. Therefore, there is a problem that it is difficult to determine the characteristics of the ground when the rock mass is sampled while taking samples of the ground.

In order to solve such a problem in the related art, as disclosed in Patent Document 1, a device capable of automatically raising and lowering a hammer at a predetermined height is mounted. However, in order to accurately measure the hard ground even when the up-down apparatus is installed in the penetration apparatus, it is troublesome to determine the rigidity characteristics by performing uniaxial or triaxial compression tests on the ground sample sampled through the sampler of the penetration apparatus .

In addition, in order to measure the characteristics of the soft ground, it was necessary to install a separate penetration testing apparatus, so it took a long time to measure the characteristics of the ground due to the rigidity measurement by the replacement of the penetration testing apparatus and the experiment .

In addition, various measurement methods based on various in situ experiments such as standard penetration test, cone penetration test, and dilatometer test are used to estimate the engineering constants of the ground by varying the measurement method of the penetration test apparatus according to the characteristics of the ground , The selection of the penetration test equipment suitable for the paperboard in the state without knowing the characteristics of the ground was left to the experience and arbitrary judgment of the expert.

Particularly, in the conventional dynamic penetration test, since energy loss occurs in the free falling process of the hammer, the dynamic energy efficiency analysis that measures the impact energy transmitted to the head has been studied. However, It is impossible to conduct an accurate ground survey because energy loss occurs during transmission through the ground.

Patent Document 1: Registration Patent No. 10-0423119 (registered on September 7, 2004)

It is an object of the present invention to provide a measuring system for measuring ground characteristics while correcting loss of energy transmitted through a rod in a ground survey using a dynamic cone penetrator.

Another object of the present invention is to provide a transmission energy correction method for correcting loss of energy transmitted through a rod in a ground survey using a dynamic cone penetrator.

A measurement system according to an embodiment of the present invention includes a dynamic cone drilling machine; A bridge box connected to the second measurement sensor and the third measurement sensor, the strain gauge being provided in the dynamic cone penetrator; An amplifier connected to the first measurement sensor and the fourth measurement sensor made of an accelerometer provided in the dynamic cone penetrator; And a control unit connected to the bridge box and the amplifier for operationally controlling the measurement results.

In the measuring system according to an embodiment of the present invention, the first measuring sensor and the second measuring sensor are mounted at the tip of the dynamic conical pipe fitting, and the third measuring sensor and the fourth measuring sensor are mounted on the head of the dynamic conical pipe fitting Is mounted.

In the measurement system according to an embodiment of the present invention, the control unit includes a synchronization unit and an operation control unit, and the synchronization unit synchronizes the strain and acceleration data transmitted from the bridge box and the amplifier and transmits the same to the operation control unit, The control unit converts the synchronized strain and the acceleration data into the load Fs and the particle velocity Va and calculates the load Fs and the particle velocity Va by the FV integral method, And calculates and corrects the energy transmitted to each of the plurality of sensors.

In the measurement system according to an embodiment of the present invention, the synchronization unit includes an oscilloscope.

In the measurement system according to an embodiment of the present invention, the second measurement sensor, the third measurement sensor, and the fourth measurement sensor are provided in pairs, respectively, so that the influence of error due to eccentric load is eliminated.

In the measurement system according to an embodiment of the present invention, the second measurement sensor or the third measurement sensor is provided in a Wheatstone Bridge connection method.

In another aspect of the present invention, there is provided a method of compensating transmission energy, comprising the steps of: (A) synchronously detecting strain and acceleration by a controller connected to the dynamic cone penetrator by dynamic penetration of a dynamic cone penetrator into a ground to be measured; (B) converting the synchronized strain and acceleration into a load (Fs) and a particle velocity (Va); And (C) calculating and correcting the energy transferred to the head and the tip of the dynamic cone pipe using the load (Fs) and the particle velocity (Va).

The transmission energy correction method according to another embodiment of the present invention may further include the step of (D) measuring the ground characteristics using the correction result of the energy transmitted to the distal end portion of the control unit.

In the transmission energy correction method according to another embodiment of the present invention, the step (A) includes the steps of (A-1) a first measurement sensor mounted on the tip of the dynamic cone pipe, and a fourth measurement sensor mounted on the head of the dynamic cone pipe, Synchronizing the acceleration data detected by the measurement sensor with the synchronization unit through the amplifier; And (A-2) a second measuring sensor mounted on a distal end of the dynamic cone pipe fitting and a third measuring sensor mounted on a head of the dynamic cone fitting device, And the step (A-1) and the step (A-2) are simultaneously performed at the same sampling rate in the synchronization unit.

In the transmission energy correction method according to another embodiment of the present invention, the step (B) may further include the step of: (B-1) calculating a change (? _Vout ) of the output voltage according to the change of the synchronized strain

(where the slope between the constant α is a change in the output voltage and the dynamic cone resistance obtained through calibration experiments using an intrusion from the ambient temperature value or predetermined in accordance with the ground to be measured (△ V _out))

Into a load (Fs) that can be expressed by a tip load (Fs _tip ) applied to a tip end portion of the dynamic cone pipe fitting and a tofu load (Fs _head ) applied to a head portion of the dynamic cone pipe fitting portion according to a proportional relation between the dynamic cone fitting portion and the dynamic cone fitting portion. (B-2) integrating the synchronized acceleration data with respect to time at each of a front end portion and a head portion of the dynamic cone pipe tubing to calculate a _front particle velocity (Va _tip ) of the dynamic cone pipe fitting and a head portion (Va) at which the particle velocity (Va _tip ) can be expressed; And (B-3) multiplying the particle velocity Va by the impedance EA / C

(Where E is the modulus of elasticity of the dynamic cone pipe, A is the cross-sectional area of the dynamic cone pipe, and C is the wave along which the stress wave propagates along the dynamic cone penetrator)

(Fa) acting as a force (Fa _tip ) acting on the tip of the dynamic cone pipe fitting (Fa _tip ) and a force acting on the head of the dynamic cone fitting device (Fa _toe ), and The steps (B-1) to (B-3) may be performed separately for the front end and the head of the dynamic cone pipe.

In the transmission energy correction method according to another embodiment of the present invention, the step (C) includes the steps of: (C-1) calculating the load Fs and the particle velocity Va )

Calculating an energy (E1) transmitted to the tip of the dynamic cone pipe and a transfer energy (E2) for the head, respectively; And (C-2) an energy E1 transferred to the tip of the dynamic cone pipe and a tip end load (Fs _tip ) applied to the tip _end

(R is the correction value for the front end transmission energy, E1 is the energy delivered to the tip end, Fs is _{the front end} being the front end load applied to the leading end)

And calculating an energy correction value R defined by a relational expression of < EMI ID = 1.0 >

The features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings.

Prior to this, terms and words used in the present specification and claims should not be construed in a conventional, dictionary sense, and should not be construed as defining the concept of a term appropriately in order to describe the inventor in his or her best way. It should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention.

The measuring system according to the present invention can detect the transmission energy of the tip part by the hammer striking by using the dynamic cone penetrator without influence of the energy loss and measure the characteristic of the ground itself independent of the hammer striking.

The transmission energy correction method according to the present invention calculates the synchronized strain and acceleration data, calculates the energy transferred to the tip portion by using the FV integration method, calculates the energy correction value, There is an effect that the transmission energy can be clearly detected.

1 is a cross-sectional view of a metrology rod according to an embodiment of the invention;
2 is a cross-sectional view of a head rod according to one embodiment of the present invention.
3 is a cross-sectional view of a cone penetration tester according to an embodiment of the present invention.
4 is a schematic diagram of a system for measuring the characteristics of a ground using a dynamic cone penetrator according to one embodiment of the present invention.
5 is a flowchart illustrating a method of calibrating a transmitted energy according to another embodiment of the present invention.
FIG. 6 is a graph showing the forces calculated from the head load and the acceleration change calculated from the strain changes detected at the head of the dynamic conical tube according to the transmission energy correction method according to another embodiment of the present invention.
FIG. 7 is a graph showing a force calculated from a change in the tip end load and an acceleration, which are estimated from the change in strain detected at the tip of the dynamic conical tube according to the transmission energy correction method according to another embodiment of the present invention.
8 is a graph of energy calculated for the head and tip of a cone penetration tester according to another embodiment of the present invention.
FIG. 9 is a graph showing a transfer energy change of a head and a tip according to penetration depth of a cone penetration tester according to another embodiment of the present invention.
FIG. 10A is a graph illustrating the detection of the tip load according to the penetration depth before the transmission energy correction method according to another embodiment of the present invention is applied. FIG.
FIG. 10B is a graph obtained by correcting the tip end load according to the depth of penetration after the application of the transmission energy correction method according to another embodiment of the present invention by the energy correction value. FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The objects, particular advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. It should be noted that, in the present specification, the reference numerals are added to the constituent elements of the drawings, and the same constituent elements are assigned the same number as much as possible even if they are displayed on different drawings. Also, the terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 2 is a cross-sectional view of a head rod according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of a cone penetration tester according to an embodiment of the present invention. FIG. to be.

The dynamic cone penetrator according to one embodiment of the present invention includes the metering rod 100 shown in Figure 1, the head rod 200 shown in Figure 2, the hammer portion 300 shown in Figure 3, and the length- ).

Specifically, the measuring rod 100 includes a cone 111 formed in a conical shape, a penetration tip 110 including a first coupling portion 113 formed to protrude from a bottom surface of the cone 111, And a second coupling part 123 protruding from one end of the main body 121 and coupled to the first coupling part 113 and a third coupling part 160 protruding from the other end, (120).

The cone 111 is a member that is coupled to one end of the rod 120 and penetrates the ground when a load is applied to the other end of the rod 120. [ Here, the cone 111 is formed in a conical shape, and may be a shape of a humanoid horn to facilitate penetration into the ground. At this time, the tip angle (?) Formed by the busbars and the bottom surface of the snakes is not limited to a specific angle but can be adjusted according to the ground conditions and the ground survey purpose.

The rod 120 is a member that engages with the cone 111 and transfers the load to the cone 111 when a load is applied to the other end of the rod 120. [ Therefore, when a load is applied to the rod 120, the cone 111 penetrates the ground, and the rod 120 is deformed due to resistance. Thus, when an external force is applied to an object, the object is deformed due to resistance, and the degree of such strain is referred to as strain.

The main body 121 of the rod 120 is formed into a tubular shape having a constant cross section. Here, the constant tubular shape does not mean that the outer diameter D and the inner diameter M of the transverse section are mathematically completely the same along the longitudinal direction of the main body 121, (D) and the inner diameter (M) due to machining errors and the like. At this time, the dimensions, lengths and materials of the outer diameter D and the inner diameter M of the main body 121 can be adjusted according to the ground conditions and the ground survey purpose.

When the cross section of the rod 120 is complicatedly formed, the energy due to the load is lost due to the complicated structure of the rod 120 when the rod 120 penetrates the ground due to the load, do. Therefore, by forming the transverse section of the main body 121 into a constant tubular shape, it is possible to prevent the energy loss due to the load, so that the accurate tip resistance can be measured.

The main body 121 is engaged with the cone 111 by the second engaging portion 123 being engaged with the first engaging portion 113. [ Here, the second engaging part 123 and the first engaging part 113 can be screwed together. Since the cross section of the area where the first engaging part 113 and the second engaging part 123 are engaged is the same as the cross section of the main body 121, the cross section of the rod 120 is kept constant, Prevent energy loss. As a result, accurate tip resistance can be measured.

The rod 120 may include a first measurement sensor 130 for measuring energy transmitted to the cone 111 by an applied load. At this time, the first measurement sensor 130 is mounted on the bottom surface of the cone 111, so that energy loss due to the load can be prevented without being affected by the cross section of the rod 120. Therefore, the first measurement sensor 130 can be used to measure the accurate tip resistance.

Also, since the first measurement sensor 130 is mounted on the bottom surface of the cone 111, energy loss due to the length of the rod 120 is not required to be considered, so that the impact energy transmitted to the ground can be accurately measured. Here, the first measurement sensor 130 may be an accelerometer, and the accelerometer may be mounted on the bottom surface of the cone 111 by screwing.

On the other hand, the second measuring sensor 140 may be mounted on the rod 120 adjacent to the penetration tip 110 to measure the tip resistance. Here, the tip resistance is an element that can evaluate the rigidity of the ground as a resistance to the penetration tip 110 when the rod 120 receives a load and penetrates the ground.

The second measurement sensor 140 may be a strain gage, and may include a front end strain gauge 141 and a rear end strain gauge 142.

When a load is applied to the rod 120 and the tip end strain gauge 141 is attached to the rod 120 to measure the tip end resistance force, the change in strain generated in the rod 120 by the load is detected by the tip strain gauge 141, And the rear stage strain gauge 142 are converted into a change in electrical resistance, whereby the load can be measured by an electrical signal. At this time, the electrical signal is converted into a load, and the converted load is divided into the cross-sectional area of the cone 111 and can be detected by the tip resistance according to the depth.

At this time, since the second measuring sensor 140 is mounted inside the rod 120, when the rod 120 penetrates by the load, the second measuring sensor 140 is not affected by the frictional force with the ground, .

Specifically, the leading end strain gauge 141 of the second measuring sensor 140 can be mounted close to the cone 111 to detect the leading end resistance force, and the trailing end strain gauge 142 can detect the load resistance from the leading end strain gauge 141, And the resultant force of the tip end resistance force and the main surface frictional force can be measured. Here, the main surface friction force is a frictional force acting along the main surface of the rod 120, and can be obtained by using the difference between the value detected by the rear stage strain gauge 142 and the value detected by the front strain gauge 141. Of course, the second measuring sensor 140 can detect only the leading end resistance force by mounting only the leading end strain gauge 141 without the trailing end strain gauge 142.

As shown in FIG. 2, the head rod 200 includes a fourth coupling portion 260 formed in one side and a fifth coupling portion 250 protruding from the other side in the same tubular shape as the cross section of the rod 120 A coupler 220 coupled to the outer circumferential surface of the main body 210, a third measurement sensor 230 mounted on one side of the inner circumferential surface of the main body 210, and a fourth measurement sensor 240).

Specifically, the fourth engaging portion 260 of the head rod 200 is engaged with the outer diameter D and the inner diameter M of the third engaging portion 160 of the measuring rod 100, (250) is connected to the hammer part (300) for applying a load. Since the cross section of the region where the third and fourth couplers 160 and 260 are coupled is the same as the cross section of the body 210 and is formed to be the same as the cross section of the rod 120, It is possible to measure the accurate tip resistance by preventing loss.

The third measurement sensor 230 is a strain gauge mounted on the inner circumferential surface of the head rod 200 corresponding to the head portion. When the dynamic cone penetrator is introduced into the ground by the load, the resistance measured by the tip of the rod 120 and the resistance measured by the head are different from each other. Therefore, in order to compare the resistance of the tip of the rod 120 with the resistance of each of the heads, (230) can measure the resistance force applied to the head rod (200). At this time, the third measurement sensor 230 can be mounted on the inner circumferential surface of the head rod 200 in pairs.

The fourth measuring sensor 240 is an accelerometer mounted on both sides of the coupler 220 for measuring the acceleration in the head and is measured at the tip of the rod 120 and at the head when the dynamic cone penetrator is introduced by the load Since the acceleration is different, the acceleration applied to the head rod 200 is measured. Here, in order to measure the resistance and acceleration at the head, the fourth measuring sensor 240 may be mounted at the same height as the third measuring sensor 230.

The fourth measuring sensor 240 is attached to the coupler 220 coupled to the outer circumferential surface of the head rod 200 to be spaced apart from the outer circumferential surface of the body 210 of the head rod 200, When a load is applied, it may not be directly affected.

In addition, the second measurement sensor 140, the third measurement sensor 230, and the fourth measurement sensor 240 are mounted in pairs, respectively, so that errors due to eccentric load can be reduced. Specifically, the second measuring sensor 140, the third measuring sensor 230 and the fourth measuring sensor 240 are each formed as a biaxial, and the temperature of the second measuring sensor 140, And can be mounted using an active-dummy method.

In particular, the second measurement sensor 140 and the third measurement sensor 230 may constitute a circuit using a Wheatstone Bridge connection method in order to amplify an output value according to a minute variation amount. Here, the Wheatstone bridge uses a principle in which a potential difference is generated in a diagonal direction in accordance with a change in resistance.

At this time, in order to have the potential difference of the point facing diagonally in the diagonally opposite direction, the whitestone bridge has a zero value, and the resistance value has the same value regardless of the specific resistance value. The strain gauge constituting each of the two measuring sensor 140 and the third measuring sensor 230 takes charge, thereby changing the strain to a voltage state.

The load applying hammer portion 300 may include a hammer 310 and an anvil 320 coupled between the main body 210 of the head load 200 and the hammer 310 as shown in FIG.

Specifically, the hammering unit 300 may be connected to the fifth engaging unit 250 of the head rod 200 to use a hydraulic device for charging the other end of the head rod 200. Here, a variety of hydraulic devices can be adopted. When the hydraulic device applies a load to the head load 200, the rod 120 is inserted into the ground.

The anvil 320 serves to transmit the force of the hammer 310 to the head rod 200 and prevent the head rod 200 from being damaged by the hammer 310. The anvil 320 includes a hammer 310, The hammer guide 330 may be protruded in a direction in which the arm 310 drops. At this time, since the hammer guide 330 is formed to penetrate the hammer 310, the hammer 310 moves along the hammer guide 330 to strike the anvil 320.

That is, since the hammers 310 are disposed to strike the anvil 320 along a certain path along the hammer guide 330, the same energy is transmitted to the cone penetration tester and the rigidity of the ground penetrated by the measurement sensors 130, 140, And other characteristics can be accurately measured.

The length-adjusting rod 400 has the same cross-section as the cross-section of the measuring rod 100 and the head rod 200, so that energy loss due to the load can be prevented and accurate tip resistance can be measured. At this time, the length-controlling rod 400 can be selected in length depending on the depth of penetration.

The dynamic cone penetrator constructed as described above can accurately detect the characteristics of the ground by excluding the influence of the rod itself during measurement by forming the rod into a tubular shape having a constant transverse section and mounting the measurement sensor inside the rod.

Further, the dynamic cone penetrator according to the present invention can improve the objectivity of the measurement data by measuring the energy transmitted to the penetration tip at the time of tube insertion without being affected by the energy loss due to the rod length by mounting the accelerometer in the cone have.

Hereinafter, a system for measuring characteristics of a ground using a dynamic cone penetrator according to an embodiment of the present invention will be described with reference to FIG. 4 is a schematic diagram of a system for measuring the characteristics of a ground using a dynamic cone penetrator according to an embodiment of the present invention.

The measuring system having a dynamic cone penetrator according to an embodiment of the present invention includes a dynamic cone drilling machine shown in FIG. 3, a second measuring sensor 140 having a strain gauge, and a bridge box (not shown) connected to the third measuring sensor 230 And a bridge box 500. The first measurement sensor 130 and the fourth measurement sensor 240 are connected to an amplifier 600 and a bridge box 500 and an amplifier 600, And a control unit 700 for controlling the operation.

Specifically, the bridge box 500 is connected to the second measuring sensor 140 and the third measuring sensor 230, detects the strain variation due to the load detected through the strain gage as a voltage, and transmits the detected strain to the controller 700 do.

The control unit 700 includes a synchronization unit 710 and an operation control unit 720. The control unit 700 synchronizes the strain and acceleration data transmitted from the bridge box 500 and the amplifier 600 and controls the transmission energy of the tip portion and the head portion, It is possible to perform arithmetic correction.

More specifically, the synchronization unit 710 synchronizes the bridge box 500 and the amplifier 600 to the bridge box 500 and the amplifier 600 in order to detect the strain and the acceleration data transmitted from the bridge box 500 and the amplifier 600 at the same sampling rate A connected 4-channel oscilloscope is available. Of course, the synchronization unit 710 may be a component integrated with the operation control unit 720 or other device capable of detecting the strain and acceleration data transmitted from the bridge box 500 and the amplifier 600 at the same sampling rate, .

The operation control unit 720 is a computer connected to the synchronization unit 710. The operation control unit 720 calculates the strain and acceleration data detected at the same sampling rate in the synchronization unit 710 and calculates the energy transmitted to the tip and head using the FV integration method. And then calibrated.

Accordingly, the operation control unit 720 can clearly detect the transmission energy of the tip portion due to the hitting of the hammer 310 without affecting the energy loss, and can measure the characteristics of the ground itself independent of the hitting of the hammer 310.

Hereinafter, a transmission energy correction method according to another embodiment of the present invention will be described with reference to FIGS. 5 to 10B.

FIG. 5 is a flowchart illustrating a method of calibrating a transmitted energy according to another embodiment of the present invention. FIG. 6 is a graph illustrating a change in strain detected at a head portion of a dynamic conical tube according to a transmitted energy correction method according to another embodiment of the present invention. And FIG. 7 is a graph showing a relationship between a head end load calculated by a change in the strain detected at the tip of the dynamic conical pipe according to the transmission energy correction method according to another embodiment of the present invention, FIG. 8 is a graph of energy calculated for head and tip of a cone penetration tester according to another embodiment of the present invention. FIG. Transmission energy change of head and tip according to depth of penetration of cone penetration tester according to the transmission energy correction method according to another embodiment FIG. 10A is a graph showing a tip end load according to a penetration depth before a transmission energy correction method according to another embodiment of the present invention is applied, and FIG. 10B is a graph illustrating a transmission energy correction method according to another embodiment of the present invention. And is corrected by the energy correction value for the tip end load according to the penetration depth after application.

The transmission energy correction method according to another embodiment of the present invention detects and compensates transmission energy by using a measuring system having a dynamic cone penetrator shown in FIG. 4, thereby detecting energy independent of the hammer striking Correction method.

In the transmission energy correction method according to another embodiment of the present invention, the dynamic cone penetrator is dynamically intruded on a ground to be measured, and then the strain and acceleration are synchronously detected (S510).

Specifically, a dynamic cone penetrator is installed on the ground to be measured, and the force of the hammer 310 is transmitted to the head rod 200 to be dynamically introduced, The second measuring sensor 140, the third measuring sensor 230, and the fourth measuring sensor 240. [0034] FIG.

The acceleration data detected through the first measurement sensor 130 and the fourth measurement sensor 240 are amplified by the amplifier 600 and transmitted to the synchronization unit 710 of the control unit 700, 140 and the third measurement sensor 230 are amplified by the bridge box 500 and transmitted to the synchronization unit 710 of the control unit 700.

The synchronization unit 710 of the control unit 700 synchronizes the strain and the acceleration at the same sampling rate of 20 kHz while being simultaneously connected to the bridge box 500 and the amplifier 600 .

After synchronizing the strain and the acceleration, the operation control unit 720 of the control unit 700 converts the strain and acceleration data detected in synchronization to the load Fs and the particle velocity Va (S520).

Specifically, the strain gage constituting the second measurement sensor 140 and the third measurement sensor 230 converts the change in the load applied to the mounted dynamic cone penetrator into a change in the electrical resistance. When a minute load is measured, a small fluctuation of the strain can be amplified using a connection method of the second measurement sensor 140 and the third measurement sensor 230, that is, a Wheatstone bridge connection method .

, The relationship between the input voltage and the output voltage in the Wheatstone bridge is as shown in the following Equation (1).

Here, Rx and? Rx represent resistance and resistance increase amounts of the x-th strain gauge constituting the second measurement sensor 140 and the third measurement sensor 230, respectively, and Vin and Vout denote the input voltage and the output voltage, respectively do. The relationship between the resistance and the resistance increase amount of each strain gage constituting the second measuring sensor 140 and the third measuring sensor 230 can be expressed by the strain in the elastic body as shown in Equation (2).

Where K is the gauge factor of the strain gage and is the eigenvalue of the strain gage. Also, ε ₁ , ε ₂ , ε ₃ , and ε ₄ are the strains measured at each strain gage.

The strain gauge causes the change in strain due to the load to appear as a change in the output voltage (ΔV _out ). This change in output voltage (△ V _out) can be calculated with a load (Fs) load (Fs) by calculating the constants α, as, [Equation 3] below, since the characteristics and having a proportional relationship.

Here, the? Constant is a slope between the tip resistance of the cone 111 obtained by a calibration experiment using a dynamic cone penetrator at room temperature and a change (? V _out ) of the output voltage.

The load Fs thus calculated is calculated from the tip end load (Fs _tip ) estimated by the change? V _out of the output voltage detected from the tip strain gauge 141 of the dynamic cone piping and the load (Fs _head ) calculated by the change? V _out of the output voltage detected from the measurement sensor 230. [

On the other hand, the arithmetic and control unit 720 integrates the acceleration data detected through the first measurement sensor 130 and the fourth measurement sensor 240, respectively, to calculate the _front particle velocity (Va _tip ) of the dynamic cone- And the particle velocity (Va) which can be expressed by the head particle velocity (Va _head ) of the dynamic cone pipe.

At this time, the particle velocity Va converted to the tip and head of the dynamic cone pipe is multiplied by the impedance (EA / C) of the cone pipe as shown in the following equation (4) Can be expressed as an acting force (Fa) that can be expressed as force (Fa _tip ) and force acting on the head of a dynamic cone pipe (Fa _tofu ).

(Where E is the modulus of elasticity of the cone, A is the cross-sectional area of the cone, and C is the shear wave propagating along the cone penetrator)

The load Fs estimated from the change in strain detected at the head portion and the tip portion of the dynamic conical pipe and the force Fa calculated from the acceleration change can be respectively shown. For example, as shown in Fig. 6, (Fs _head ) estimated from the change of the strain detected in the test piece and the force (Fa _head ) calculated by the acceleration change. As shown in Fig. 6, since the head of the dynamic conical pipe does not reflect the wave due to the ground resistance and the impedance change of the dynamic conical pipe at the beginning, the head load (Fs _head ) indicated by "I" and the force indicated by "II" (Fa _tofu ) increases simultaneously.

However, after the proportional interval, the force (Fa _head ) increases while the head load (Fs _head ) decreases. This is because the total length of the dynamic cone drilling is shorter than the length required for the impact energy of the hammer 310 to be sufficiently exhibited, and it is judged to be the influence of the initial tensile wave.

On the other hand, also it does not have a proportional relationship between a history of 7 as in the dynamic kongwan wear of the front end portion of the ground because of the resistance which the front end load shown as "Ⅰ" (Fs _{front end)} of the hysteresis and the force indicated by "Ⅱ" (Fa _tip) , The tip load (Fs _tip ) is detected more than twice as much as the force acting on the _head (Fa _head ).

In the vicinity of 5 ms, the impact of the tip end load (Fs _tip ) and the tip _end due to the impact of the second impact of the hammer 310 is affected by the superimposed effect as the transmitted compressive wave is changed to the tensile wave because the ground resistance of the tip end is small. (Fa _tip ) were observed to increase.

In response to this result, the arithmetic and control unit 720 simultaneously calculates and calibrates the impact energy transmitted to the head portion and the head portion of the dynamic conical pipe (S530).

Specifically, the operation control unit 720 simultaneously calculates the batting energy transmitted to the head and the head of the dynamic conical tube using the F-V integral method.

The arithmetic and control unit 720 converts the strain and acceleration data detected through the third measuring sensor 230 and the fourth measuring sensor 240 mounted on the head to calculate the striking energy delivered to the head of the dynamic conical tube, One head load (Fs _head ) and particle velocity (Va _head ) are calculated according to the following equation (5).

At the same time, the arithmetic control unit 720 calculates the acceleration data and strain detected through the first measuring sensor 130 and the front end strain gauge 141 mounted on the tip end, to calculate the impact energy transmitted to the tip of the dynamic conical pipe fitting (Front _end of Fs) and the particle velocity ( _{front end} of Va) in accordance with the following equation (5).

In order to simultaneously calculate the transfer energies E2 and E1 of the head and the head of the dynamic conical pipe using this FV integration method, the strain and acceleration are calculated at the same time intervals of "dt " in the state of being connected to the synchronization unit 710, It is necessary to detect the data. Accordingly, a synchronization unit 710 such as an oscilloscope that detects strain and acceleration data at the same sampling rate can be connected and solved.

As a result of the calculation of the FV integration method, the theoretical potential energy of the hammer 310 is 45 Nm as shown in FIG. 8, while the energy delivered to the head of the dynamic connering indicated by "E2" is 33 Nm and "E1 Quot ;, the energy delivered to the tip of the dynamic cone drilling indicated as 23 Nm.

This energy loss is detected differently depending on the depth of penetration of the dynamic conical tube, and as shown in FIG. 9, the transmission energy E1 at the tip end is always smaller than the energy E2 transmitted to the head. This shows that it is necessary to compensate the energy (E1) transferred to the tip in consideration of energy loss in the ground evaluation by dynamic penetration of the dynamic conical pipe.

Accordingly, the energy correction value R relating to the tip end load (Fs _tip ) applied to the tip _end portion and the maximum energy (E1) transmitted to the tip end portion is calculated as a parameter capable of performing the ground evaluation without considering the energy loss, 6].

(Where R is the correction value of the tip transfer energy, E1 is the maximum energy delivered to the _tip , Fs _tip is the tip load applied to the tip).

According to the equation (6) for this energy correction value R, the tip end load (Fs _tip ) applied to the tip end, such as the tip end resistance detected at the tip end according to the penetration depth shown in Fig. 10A, The maximum energy E1 may be calculated and expressed as a graph of a correction value R of the tip energy according to the depth of penetration as shown in FIG. 10B.

The ground characteristics can be measured from the correction value R graph of the tip energy (S540).

For example, the graph of the tip end load (Fs _{tip end} ) applied to the tip end portion such as the tip end resistance detected at the tip end portion according to the penetration depth shown in Fig. 10A is compared with the correction value R graph of the tip end energy shown in Fig. It can be carefully observed from the correction value R graph of the tip energy shown in Fig. 10B that the soft ground layer exists at an intermediate penetration depth of 400 to 550 mm.

Accordingly, the transmission energy correction method according to another embodiment of the present invention calculates the synchronized detected strain and acceleration data, calibrates and calibrates the energy transferred to the tip portion by using the FV integration method, It is possible to clearly detect the transmission energy of the tip portion due to the impact.

Accordingly, the transmission energy correction method according to another embodiment of the present invention provides an energy correction value R that can measure the characteristics of the ground itself independent of the hitting of the hammer 310, .

Although the technical idea of the present invention has been specifically described according to the above preferred embodiments, it is to be noted that the above-described embodiments are intended to be illustrative and not restrictive.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention.

100: measurement rod 110: intrusion tip
111: cone 120: rod
121, 210: main body 130: first measuring sensor
140: second measurement sensor 141: tip strain gauge
142: rear stage strain gauge 200: head load
220: coupler 230: third measuring sensor
240: fourth measuring sensor 300: hammer part
310: hammer 320: anvil
400: Length control rod 500: Bridge box
600: amplifier 700:

Claims (11)

Dynamic Conduit Wear;
A bridge box connected to the second measurement sensor and the third measurement sensor, the strain gauge being provided in the dynamic cone penetrator;
An amplifier connected to the first measurement sensor and the fourth measurement sensor made of an accelerometer provided in the dynamic cone penetrator; And
A control unit connected to the bridge box and the amplifier for operationally controlling the measurement result; Lt; / RTI >
Wherein the control unit includes a synchronization unit and an operation control unit,
Wherein the synchronization unit synchronizes the strain and acceleration data transmitted from the bridge box and the amplifier to the operation control unit,
Wherein the operation control unit converts the synchronized strain and acceleration data into a load Fs and a particle velocity Va and calculates the load Fs and the particle velocity Va by an FV integral method, And the energy transmitted to the distal end portion are calculated and corrected.
The method according to claim 1,
Wherein the first measuring sensor and the second measuring sensor are mounted on the tip of the dynamic conical tube,
And the third measuring sensor and the fourth measuring sensor are mounted on the head of the dynamic conical pipe fitting.
delete The method according to claim 1,
Wherein the synchronization unit comprises an oscilloscope.
The method according to claim 1,
Wherein the second measuring sensor, the third measuring sensor and the fourth measuring sensor are provided in pairs, respectively, so as to eliminate the influence of error due to the eccentric load.
The method according to claim 1,
Wherein the second measurement sensor or the third measurement sensor is provided with a Wheatstone Bridge connection method.
(A) synchronously detecting strain and acceleration by a control unit connected to the dynamic cone penetrator by dynamically penetrating the ground where the dynamic cone penetrator is to be measured;
(B) converting the synchronized strain and acceleration into a load (Fs) and a particle velocity (Va); And
(C) calculating and correcting the energy transferred to the head and the tip of the dynamic cone pipe using the load (Fs) and the particle velocity (Va), respectively;
/ RTI >
8. The method of claim 7,
(D) measuring the ground property using the correction result of the energy transmitted to the front end portion by the control portion.
8. The method of claim 7,
The step (A)
(A-1) The acceleration data detected through the first measurement sensor mounted on the tip of the dynamic cone pipe and the fourth measurement sensor mounted on the head of the dynamic cone pipe are synchronously detected by the synchronizer through the amplifier step; And
(A-2) A second measuring sensor mounted on a distal end of the dynamic cone pipe and a third measuring sensor mounted on a head of the dynamic cone pipe are synchronously detected by a synchronizer through a bridge box step;
Lt; / RTI >
Wherein the steps (A-1) and (A-2) are simultaneously performed at the same sampling rate in the synchronization unit.
8. The method of claim 7,
The step (B)
(B-1) a change (DELTA _Vout ) of the output voltage according to the change of the synchronized strain

(? constant is a slope between a tip resistance obtained through a calibration experiment using the dynamic cone penetrator at room temperature and a change (? V _out ) of the output voltage)
Into a load (Fs) that can be expressed by a tip load (Fs _tip ) applied to a tip end portion of the dynamic cone pipe fitting and a tofu load (Fs _head ) applied to a head portion of the dynamic cone pipe fitting portion according to a proportional relation between the dynamic cone fitting portion and the dynamic cone fitting portion.
(B-2) integrating the synchronized acceleration data with respect to time at each of a front end portion and a head portion of the dynamic cone pipe tubing to calculate a _front particle velocity (Va _tip ) of the dynamic cone pipe fitting and a head portion Converting said particle velocity (Va), which can be represented by a particle velocity (Va _head ); And
(B-3) The particle velocity Va is multiplied by the impedance EA / C

(Where E is the modulus of elasticity of the dynamic cone pipe, A is the cross-sectional area of the dynamic cone pipe, and C is the wave along which the stress wave propagates along the dynamic cone penetrator)
Into a force (Fa) that can be expressed by a force (Fa _tip ) acting on the tip of the dynamic cone pipe and a force acting on the head of the dynamic cone pipe (Fa _toe );
Lt; / RTI >
Wherein the steps (B-1) to (B-3) are performed separately for the front end and the head of the dynamic cone pipe.
11. The method of claim 10,
The step (C)
(C-1) The control unit calculates a load (Fs) and a particle velocity (Va) separately calculated for the front end portion and the head portion of the dynamic cone-

Calculating an energy (E1) transmitted to the tip of the dynamic cone pipe and a transfer energy (E2) for the head, respectively; And
(C-2) The energy E1 transferred to the tip of the dynamic cone pipe and the tip end load (Fs _tip ) applied to the tip _end

(R is the correction value for the front end transmission energy, E1 is the energy delivered to the tip end, Fs is _{the front end} being the front end load applied to the leading end)
Calculating an energy correction value R defined by a relational expression;
Wherein the transmission energy correction method comprises the steps of:

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