KR102321080B1 - In situ ground property detection system - Google Patents

Abstract

According to an embodiment of the present invention, provided is a system for detecting the in situ recovery modulus of the strata of interest. The system comprises: a dynamic strike unit which performs a dynamic strike for each stratum depth; a measuring unit for measuring a load-displacement signal due to a dynamic blow; and an operation unit for processing data obtained from the measuring unit. The mechanical properties of a ground material can be detected by the depth of the strata.

Description

In situ ground property detection system {IN SITU GROUND PROPERTY DETECTION SYSTEM}

An in situ ground characteristic detection system is disclosed.

American Highway and Transportation Association (American Association of State Highway and Transportion Ofiicials; AASHTO) has like design method apply the Resilient Modulus (M _R), the mechanical properties of the material rather than the strength of the soil, such as CBR value or R-value. Accordingly, a force-displacement dynamic signal is measured by performing a dynamic strike on the stratum in a state where penetration into the stratum of interest is made, and the elastic modulus of recovery of the material constituting the ground may be calculated based on the measured dynamic signal.

Stiffness, which is one of the physical properties of the material of the stratum of interest constituting the ground, is treated as a parameter in the region where the strain is small in the stress versus strain graph, and the elastic modulus and the like can be derived from it. In general, when a dynamic load is applied to the ground, the stress is periodically released, and the resulting total strain is the sum of the plastic strain due to plastic deformation and the recovery strain due to elastic deformation. The modulus of elasticity is calculated as the ratio of the above stress to this total strain. Furthermore, the recovery elastic modulus is calculated as the ratio of stress to recovery strain by considering only recovery strain due to elastic deformation, excluding plastic strain due to plastic deformation. Due to the elastic modulus of recovery, a more accurate prediction can be provided for analysis of ground characteristics for road design and the like.

The above-mentioned background art is possessed or acquired by the inventor in the process of deriving the disclosure of the present application, and it cannot be said that it is necessarily known technology disclosed to the general public prior to the present application.

Korean Patent Publication No. 10-2014-0062840 (published on May 26, 2014)

SUMMARY OF THE INVENTION It is an object of one embodiment to provide a system for detecting the elastic modulus of recovery at a point using a penetration tester that performs a dynamic strike at an in situ location of a formation of interest.

A system for detecting an in-situ recovery elastic modulus of a stratum of interest according to an embodiment includes: a dynamic striking unit that performs a dynamic strike for each stratum depth; a measuring unit for measuring a load-displacement signal due to a dynamic blow; and an operation unit for processing the data obtained from the measurement unit; may include, and detect the mechanical properties of the ground material for each stratum depth.

According to one side, the measuring unit a first sensor for measuring a dynamic load response due to the dynamic striking of the dynamic striking unit; and a second sensor for measuring a dynamic displacement response due to the dynamic striking of the dynamic striking unit.

According to one side, the calculation unit selects the maximum load among the axial loads, divides the maximum load by the cross-sectional area to calculate the axial stress, and only the dynamic displacement response from the first dynamic strike during the dynamic striking repetition of the dynamic striking unit can be selected, and the strain can be calculated from the dynamic displacement response.

According to one side, the calculating unit may extract a recovery strain excluding the plastic strain from the strain, and calculate a recovery elastic modulus through the recovered strain and the axial stress.

여기서, Mr은 회복 탄성계수고, σ _d 은 축방향 응력이고 ε _r 은 회복 변형률을 나타낸다. According to one side, the elastic modulus of recovery is obtained through the following,

Here, Mr is the elastic modulus of recovery, σ _d is the axial stress and ε _r is the recovery strain.

According to one side, the dynamic striking unit, including a penetration tester for measuring the properties of the ground material of the stratum of interest, the penetration tester, the support; and a head coupled to the support and performing a dynamic strike against the formation of interest, wherein the head has a tip penetrating the formation of interest, and the tip of the head includes a flat portion forming the same plane At least a portion of the head may be formed to increase the diameter of the head so that the cross-sectional area of the head increases along the penetration direction.

According to one side, based on the setting mode may further include a control unit for adjusting the dynamic strike energy of the head, the setting mode is a penetration mode in which the head penetrates the ground; and a dynamic reaction test mode for measuring the dynamic stiffness of the ground, wherein the control unit performs a dynamic strike by the head with a first dynamic striking energy in the penetration mode, and the second in the dynamic reaction test mode The dynamic striking energy of the head may be adjusted so that the head performs the dynamic striking with a second dynamic striking energy less than 1 dynamic striking energy.

The in-situ ground characteristic detection system according to an embodiment may evaluate the elastic modulus of recovery of each of the layers of the composite structure below the ground.

The in-situ ground characteristic detection system according to an embodiment may stably acquire a dynamic signal of a stratum of interest.

The in-situ ground characteristic detection system according to an embodiment may observe the moisture content and the dynamic impact part drop height affecting the elastic modulus.

Effects of the in-situ ground characteristic detection system according to an embodiment are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a diagram schematically illustrating an in-situ characteristic detection system according to an embodiment.
2 is a diagram illustrating components of an in-situ characteristic detection system according to an embodiment.
3 is a diagram schematically illustrating a process of calculating a recovery elastic modulus through an in-situ characteristic detection system according to an embodiment.
4A illustrates an impulse response of a force among dynamic responses measured by a first sensor of a measurement unit according to an exemplary embodiment.
4B illustrates an impulse response of acceleration among dynamic responses measured by the first sensor of the measurement unit according to an exemplary embodiment.
5 illustrates responses of a total strain (ε _t , ), a recovered strain (ε _r ), and a plastic strain (ε _p ) due to a cyclic load according to an embodiment.
Figure 6 (a) shows the change in force according to the height from which the head of the penetration tester falls.
Figure 6 (b) shows the change in displacement according to the height from which the head of the penetration tester falls.
7 shows the change in the elastic modulus of recovery according to the influence of the height from which the head of the penetration tester falls and the moisture content.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, since various changes may be made to the embodiments, the scope of the patent application is not limited or limited by these embodiments. It should be understood that all modifications, equivalents and substitutes for the embodiments are included in the scope of the rights.

The terms used in the examples are used for description purposes only, and should not be construed as limiting. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiment belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

In addition, in the description with reference to the accompanying drawings, the same components are given the same reference numerals regardless of the reference numerals, and the overlapping description thereof will be omitted. In the description of the embodiment, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the embodiment, the detailed description thereof will be omitted.

In addition, in describing the components of the embodiment, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the components from other components, and the essence, order, or order of the components are not limited by the terms. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but another component is between each component. It will be understood that may also be "connected", "coupled" or "connected".

Components included in one embodiment and components having a common function will be described using the same names in other embodiments. Unless otherwise stated, a description described in one embodiment may be applied to another embodiment, and a detailed description in the overlapping range will be omitted.

As used herein, the term “interpenetration” refers to insertion of a component through an object. Here, the object may be used as a concept including a ground formed by a plurality of strata. For example, the penetration tester of the present disclosure may be inserted into the ground by penetrating any at least one or more formations of the ground.

As used herein, the term “stiffness” refers to a parameter (eg, displacement, strain) in a relationship of a parameter measured as a force is applied to an object, for example, a force-displacement relationship or a stress-strain relationship. is mentioned in a relatively small area. In particular, measuring the stiffness of the strata in the ground means measuring the stiffness of a portion having a relatively shallow input parameter, depth.

As used herein, the term “dynamic stiffness measurement” means measuring stiffness using dynamic energy.

As used herein, the term “interest stratum” refers to a stratum in which a measurement of a desired parameter is made.

As used herein, the term “in-situ” refers to the very location of a substance constituting an object. Here, the material constituting the object may be soil or the like. Therefore, measuring the dynamic stiffness of the stratum of interest in situ does not mean measuring the dynamic stiffness of the stratum of interest through other indirect means (eg, sound waves, etc.) from the outside, but directly at the location of the stratum of interest. It may mean measuring the dynamic stiffness of the strata of interest.

As used herein, the term “elastic modulus” is defined as the ratio of stress to strain, and “resilient modulus” belonging to a subclass of “elastic modulus” refers to the stress versus elastic deformation excluding plastic deformation. It is defined as the ratio of recovery strain due to

1 is a diagram schematically illustrating an in situ-based characteristic detection system 10 according to an embodiment.

The in-situ characteristic detection system 10 according to an embodiment may include a dynamic striking unit 100 , a measuring unit 200 , and a calculating unit 300 . The dynamic striking unit 100 performs a dynamic strike for each stratum depth, the measuring unit 200 measures the load-displacement signal by the dynamic striking, and the calculating unit 300 measures the data obtained from the measuring unit 200. can be processed

2 is a diagram illustrating components of the in-situ characteristic detection system 10 according to an embodiment.

The dynamic strike unit 100 may include a penetration tester 110 for measuring the properties of the ground material of the stratum of interest. The penetration tester 110 may include a support 111 and a head 112 coupled to the support 111 and performing a dynamic blow to the stratum of interest.

For example, the head 112 may have a distal end 113 penetrating the stratum of interest, and the distal end 113 of the head may be configured to include a coplanar flat portion 114 . Alternatively, at least a portion of the head 112 may be formed to increase the diameter of the head 112 so that the cross-sectional area of the head 112 increases along the penetration direction.

The dynamic striking unit 100 may further include a control unit (not shown) for adjusting the dynamic striking energy of the head 112 based on a setting mode. The setting mode may include a penetration mode in which the head 112 penetrates the ground and a dynamic reaction test mode in which the dynamic stiffness of the ground is measured. The controller performs a dynamic strike by the head 112 with a first dynamic striking energy in the penetration mode, and the head 112 with a second dynamic striking energy smaller than the first dynamic striking energy in the dynamic reaction test mode It is possible to adjust the dynamic striking energy of the head 112 to perform a dynamic striking.

In one example, the measurement unit 200 may be installed in the head 112 of the penetration tester (110). For example, a dynamic response signal (eg, a force-displacement signal or a stress-strain signal) may be obtained as the head 112 dynamically strikes the formation of interest. Since the dynamic response signal has a property that its shape can change according to the dynamic stiffness of the stratum that is the target of a dynamic blow, the elastic modulus of recovery of the material constituting the stratum of interest can be calculated based on the characteristic of the dynamic response signal. can

The measuring unit 200 includes a first sensor 210 that measures a dynamic load response due to the dynamic striking of the dynamic striking unit 100 during the dynamic response test and a dynamic displacement response due to the dynamic striking of the dynamic striking unit 100 . It may include a second sensor 220 for measuring.

The first sensor 210 may include a load cell or an accelerometer. The load cell or accelerometer may be mounted on the head 112 of the penetration tester 110 to measure dynamic force or acceleration. The second sensor 220 may include a displacement measurer or a strain measurer.

3 is a diagram schematically illustrating a process of calculating the elastic modulus of recovery through the in-situ characteristic detection system 10 according to an embodiment.

Referring to FIG. 3 , the in-situ characteristic detection system 10 according to an embodiment according to an embodiment may first perform boring to a set depth in the ground G ( S110 ). Thereafter, the penetration tester 110 of the in-situ ground characteristic detection system 10 according to an embodiment may be seated in the boring hole (S120).

Thereafter, by hitting the penetration tester 110 with the first dynamic striking energy E1, the tip of the penetration tester 110 may penetrate to the first depth D1 where the first stratum of interest is located (S130). Thereafter, by hitting the penetration tester 110 with the second dynamic strike energy E2 , a dynamic reaction test may be performed through the penetration tester 110 ( S140 ). Here, the second dynamic striking energy (E2) may be set to be smaller than the first dynamic striking energy (E1).

That is, information on the dynamic stress and dynamic strain in the first stratum of interest may be acquired through the in situ-based feature detection system 10 according to an embodiment, and recovery strain is extracted through this to recover in the first stratum of interest. The modulus of elasticity can be calculated.

In one embodiment, by striking the penetration tester 110 with the third dynamic striking energy (E3), the tip 113 of the penetration tester 110 can penetrate to the second depth (D2) where the second stratum of interest is located. There is (S150). Thereafter, a dynamic reaction test may be performed by hitting the penetration tester 110 with a fourth dynamic striking energy E4 that is smaller than the third dynamic striking energy E3 ( S160 ).

That is, information on the dynamic stress and dynamic strain in the second stratum of interest may be acquired through the in situ-based feature detection system 10 according to an embodiment, and recovery strain is extracted through this to recover in the first stratum of interest. The modulus of elasticity can be calculated.

Additionally, by hitting the penetration tester 110 with the fifth dynamic strike energy E5, the tip of the penetration tester 110 may penetrate to the third depth D3 where the third stratum of interest is located (S170). Thereafter, a dynamic reaction test may be performed by hitting the penetration tester 110 with a sixth dynamic striking energy E6 that is smaller than the fifth dynamic striking energy E5 ( S180 ).

That is, information on the dynamic stress and dynamic strain in the third stratum of interest may be acquired through the in situ-based feature detection system 10 according to an embodiment, and recovery strain is extracted through this to recover in the first stratum of interest. The modulus of elasticity can be calculated.

The number of intrusion and dynamic response tests can be established based on the number or characteristics of the strata of interest. The first dynamic striking energy (E1) to the sixth dynamic striking energy (E6) are set to an energy of any size suitable for the penetration tester 110 to perform a dynamic reaction test of the stratum of interest in the stratum of interest in the ground (G). In one embodiment, the penetration depths D1 , D2 , and D3 may be set based on the location where the formation of interest is formed.

As described above, since it is possible to obtain an accurate elastic modulus of recovery of a different stratum of interest at different depths from the original position through the in situ-based characteristic detection system 10 according to an embodiment, accurate characteristic data of the stratum compared to laboratory or non-destructive testing can be obtained. can be obtained

FIG. 4A shows an impulse response of a force among dynamic responses measured by the first sensor 210 of the measuring unit 200 . FIG. 4B shows an impulse response of acceleration among dynamic responses measured by the first sensor 220 of the measurement unit.

The measurement unit 200 may measure an axial load, an acceleration, etc. from the impulse response of the force and the impulse response of the acceleration. The measured data may be processed by the calculation unit 300 . The calculation unit 300 may select a maximum load among axial loads and calculate the axial stress by dividing the maximum load by a cross-sectional area.

5 illustrates responses of a total strain (ε _t , ), a recovered strain (ε _r ), and a plastic strain (ε _p ) due to a cyclic load according to an embodiment. The second sensor 220 of the measurement unit 200 may measure a dynamic displacement response or the like. The calculator 300 selects only the recovery strain εr from the total strain εt, excluding the plastic strain εp from the dynamic displacement response obtained by the second sensor 220 of the measuring unit 200, and selects the recovery elastic modulus can be used to save Specific details will be described below.

The calculating unit 300 may select only a dynamic displacement response from the first dynamic striking during the dynamic striking repetition of the dynamic striking unit, and calculate the strain from the dynamic displacement response. As shown in FIG. 5 , the dynamic displacement response measured by the second sensor 220 of the measuring unit 200 is similar to the dynamic response to the cyclic load triaxial test, the total strain is the recovery strain and the plastic strain. composed of combinations. Since the dynamic displacement response from the first dynamic blow is a combination of recovery strain and plastic strain, only the recovery strain due to elastic deformation can be extracted, except for the plastic strain.

The calculator 300 may extract a recovery strain excluding the plastic strain from the strain, and calculate a recovery elastic modulus based on the recovered strain and the axial stress.

The elastic modulus of recovery can be obtained through the following equation.

Here, Mr is the elastic modulus of recovery, σ _d is the axial stress and ε _r is the recovery strain.

The elastic modulus of recovery finally obtained in this way can be utilized in the mechanical design of ground materials such as road pavement.

Figure 6 (a) shows the force according to the height from which the head 112 of the penetration tester 110 falls, and Figure 6 (b) is a dynamic blow according to the height from which the head 112 of the penetration tester 110 falls. represents the displacement of the part of the ground subjected to 6 shows the change in impulse response according to the drop height of the head 112 of the penetration tester 110 in soil having a moisture content of 11.2%.

7 shows the change in the elastic modulus of recovery according to the influence of the height from which the head 112 of the penetration tester 110 falls and the moisture content. Specifically, the results of FIG. 6 are data when the moisture content is 11.2%, and after obtaining the experimental data as in FIG. 6 even under the conditions of the moisture content of 8.8%, 9.5%, and 10.8%, the recovery elastic modulus is based on this. The change is the result of FIG. 7 .

Referring to FIG. 7 , the elastic modulus of recovery generally increases with the height from which the head 112 of the penetration tester 110 falls. Specimens with a low moisture content at all drop heights showed a high modulus of recovery, for example, at a moisture content of 8.8%, the modulus of recovery was higher than that at a moisture content of 9.5%.

That is, the moisture content may be a factor affecting the elastic modulus of recovery of the strata of interest.

In addition, the in-situ ground characteristic detection system 10 according to an embodiment may acquire a recovery elastic modulus, and may compare the recovery elastic modulus with existing data to trace back the moisture content of the ground.

Through the in-situ ground characteristic detection system 10 according to an embodiment, it is possible to evaluate the in-situ recovery elastic modulus affected by the moisture content, dry density, and falling energy of the soil.

The in situ ground characteristic detection system 10 according to an embodiment measures a force-displacement dynamic signal by performing a dynamic strike on the stratum in a state where penetration into the stratum of interest is made, and recovers due to elastic deformation excluding plastic deformation By extracting only the strain, the elastic modulus of recovery can be calculated, and useful information can be provided for the mechanical design of ground materials such as road pavements.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and available to those skilled in the art of computer software. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic such as floppy disks. - includes magneto-optical media, and hardware devices specially configured to store and carry out program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

The software may comprise a computer program, code, instructions, or a combination of one or more thereof, which configures a processing device to operate as desired or is independently or collectively processed You can command the device. The software and/or data may be any kind of machine, component, physical device, virtual equipment, computer storage medium or apparatus, to be interpreted by or to provide instructions or data to the processing device. , or may be permanently or temporarily embody in a transmitted signal wave. The software may be distributed over networked computer systems, and stored or executed in a distributed manner. Software and data may be stored in one or more computer-readable recording media.

As described above, although the embodiments have been described with reference to the limited drawings, those skilled in the art may apply various technical modifications and variations based on the above. For example, the described techniques are performed in a different order than the described method, and/or the described components of the system, structure, apparatus, circuit, etc. are combined or combined in a different form than the described method, or other components Or substituted or substituted by equivalents may achieve an appropriate result.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

10: In situ-based feature detection system
100: dynamic strike unit
110: penetration tester
111: support
112: head
113: tip
114: flat part
200: measurement unit
210: first sensor
220: second sensor
300: arithmetic unit

Claims (7)

a dynamic strike unit that performs a dynamic strike for each stratum depth;
a measuring unit for measuring a load-displacement signal due to a dynamic blow; and
an operation unit for processing the data obtained from the measurement unit;
including,
The measuring unit
a first sensor for measuring a dynamic load response due to the dynamic striking of the dynamic striking unit; and
a second sensor for measuring a dynamic displacement response due to the dynamic striking of the dynamic striking unit;
including,
The calculation unit,
Select the maximum load among the axial loads, divide the maximum load by the cross-sectional area, and calculate the axial stress
selecting only the dynamic displacement response from the first dynamic striking during the dynamic striking repetition of the dynamic striking part, and calculating the strain from the dynamic displacement response;
the calculation unit
Extracting the recovery strain excluding the plastic strain from the strain,
Calculating the elastic modulus of recovery through the recovery strain and the axial stress,
To detect the mechanical properties of the ground material by stratum depth,
In situ ground characteristic detection system.
delete delete delete According to claim 1,
The elastic modulus of recovery is obtained through

where Mr is the elastic modulus of recovery, σ _d is the axial stress and ε _r is the recovery strain,
In situ ground characteristic detection system.
According to claim 1,
The dynamic striking unit,
A penetration tester for measuring the properties of the ground material of the stratum of interest;
The penetration tester,
support; and
a head coupled to the support for performing a dynamic strike against the formation of interest;
including,
The head has a distal end penetrating the strata of interest, and the distal end of the head comprises a coplanar flat portion,
At least a portion of the head is formed to increase the diameter of the head so that the cross-sectional area of the head increases along the penetration direction,
In situ ground characteristic detection system.
7. The method of claim 6,
Further comprising a control unit for adjusting the dynamic striking energy of the head based on the setting mode,
The setting mode is
a penetration mode in which the head penetrates the ground; and
a dynamic response test mode for measuring the dynamic stiffness of the ground;
including,
The control unit is configured such that the head performs a dynamic striking with a first dynamic striking energy in the penetration mode and the head performs a dynamic striking with a second dynamic striking energy that is smaller than the first dynamic striking energy in the dynamic reaction test mode adjusting the dynamic striking energy of the head,
In situ ground characteristic detection system.

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