KR100264630B1 - Rebar detection and detection method in concrete foundation piles by measuring 3-axis magnetic field in borehole - Google Patents
Rebar detection and detection method in concrete foundation piles by measuring 3-axis magnetic field in borehole Download PDFInfo
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- KR100264630B1 KR100264630B1 KR1019980008981A KR19980008981A KR100264630B1 KR 100264630 B1 KR100264630 B1 KR 100264630B1 KR 1019980008981 A KR1019980008981 A KR 1019980008981A KR 19980008981 A KR19980008981 A KR 19980008981A KR 100264630 B1 KR100264630 B1 KR 100264630B1
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- 239000004567 concrete Substances 0.000 title claims abstract description 16
- 238000001514 detection method Methods 0.000 title claims 5
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 41
- 238000005259 measurement Methods 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 13
- 230000006698 induction Effects 0.000 claims description 6
- 239000000523 sample Substances 0.000 claims description 4
- 238000005553 drilling Methods 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 7
- 230000005358 geomagnetic field Effects 0.000 description 7
- 239000011435 rock Substances 0.000 description 4
- 230000005415 magnetization Effects 0.000 description 3
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 2
- 239000000284 extract Substances 0.000 description 2
- 206010067484 Adverse reaction Diseases 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000006838 adverse reaction Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000011150 reinforced concrete Substances 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
- G01V3/081—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices the magnetic field is produced by the objects or geological structures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/0206—Three-component magnetometers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/36—Recording data
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/38—Processing data, e.g. for analysis, for interpretation, for correction
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V2200/00—Details of seismic or acoustic prospecting or detecting in general
- G01V2200/10—Miscellaneous details
- G01V2200/16—Measure-while-drilling or logging-while-drilling
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V2210/00—Details of seismic processing or analysis
- G01V2210/10—Aspects of acoustic signal generation or detection
- G01V2210/12—Signal generation
- G01V2210/121—Active source
- G01V2210/1216—Drilling-related
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Abstract
본 발명은 시추공 내 3-축 자기장 측정에 의한 콘크리트 기초 파일 내의 철근탐지 장치 및 방법에 관한 것으로, 그 목적은 파일내에 배근되어 있는 철근의 하부 끝지점 깊이를 용이하게 파악할 수 있는 시추공 내 3-축 자기장 측정에 의한 콘크리트 기초 파일 내의 철근탐지 장치 및 방법을 제공하는 것이다.The present invention relates to an apparatus and method for detecting rebar in a concrete foundation pile by measuring a three-axis magnetic field in a borehole. The object of the present invention is to easily determine the depth of the lower end point of the reinforcing bars in the pile. It is to provide an apparatus and method for detecting rebar in a concrete foundation pile by magnetic field measurement.
본 발명은 교각이나 대형 구조물의 기초파일에 평행하게 공을 시추하고, 상기 시추공내로 3-축 자기장 측정센서를 삽입하며, 상기 3-축 자기장 측정센서를 탐사 시추공내에서 상하로 이동하여 기초 파일내 철근의 유도 자기장을 측정함과 동시에 상기 3-축 자기장 측정센서의 깊이를 측정하고, 상기 철근의 유도 자기장 측정치와 3-축 자기장 측정센서의 깊이를 컴퓨터에 저장하여 기초파일의 하단 깊이를 측정하는 시추공 내 3-축 자기장 측정에 의한 콘크리트 기초 파일 내의 철근탐지 장치 및 탐지 방법을 제공함에 있다.The present invention drills a ball parallel to the foundation pile of a piers or large structures, inserts a three-axis magnetic field sensor into the borehole, and moves the three-axis magnetic field sensor up and down within the exploration borehole to allow the The depth of the 3-axis magnetic field measuring sensor is measured at the same time as measuring the induced magnetic field of the reinforcing bar, and the depth of the base pile is measured by storing the depth of the induced magnetic field and the 3-axis magnetic field measuring sensor of the reinforcing bar on a computer. An object of the present invention is to provide a detecting device and a method for detecting rebar in a concrete foundation pile by measuring a three-axis magnetic field in a borehole.
Description
본 발명은 시추공 내 3-축 자기장 측정에 의한 콘크리트 기초 파일 내의 철근탐지 장치 및 방법에 관한 것으로, 대규모 구조물의 콘크리트기초파일에 평행하게 시추한 공 내에서 3-축 자기장 측정을 수행하고 그 자료를 해석함으로써, 파일 내에 배근한 철근의 하부의 끝 지점(기초파일의 하부 끝 지점과 같다)의 깊이를 추출하는 시추공 내 3-축 자기장 측정에 의한 콘크리트기초파일 내의 철근탐지 장치 및 방법에 관한 것이다.The present invention relates to an apparatus and method for detecting rebar in a concrete foundation pile by measuring a three-axis magnetic field in a borehole. The present invention performs a three-axis magnetic field measurement in a bore drilled parallel to a concrete foundation pile of a large-scale structure. By analyzing, the present invention relates to an apparatus and method for detecting rebar in a concrete foundation pile by measuring a three-axis magnetic field in a borehole, which extracts a depth of a bottom end point of the reinforcing bar (referring to the bottom end point of the foundation pile).
일반적으로 교각이나 대형 구조물의 기초는 철근이 배근된 콘크리트 파일로 이루어져 있으나, 설계도면을 입수할 수 없는 경우, 기초 파일의 깊이를 파악하기 위한 연구가 국내는 물론 전세계적으로도 널리 대두되고 있다.Generally, the foundation of a pier or a large structure is composed of reinforced concrete piles. However, when a design drawing is not available, studies to grasp the depth of foundation piles have been widely applied both domestically and globally.
종래에는 파일의 깊이를 효과적으로 알아내는 방법이 없어서 파일의 깊이를 대략적으로 가정해 왔으며, 특수한 경우에는 주변 지반의 개착으로 해결하였다. 이러한 기초 파일의 깊이 파악을 위한 방법으로는 평행탄성파법(parallel seismics)과 자기경도법이 있다.Conventionally, since there is no method of effectively determining the depth of the pile, the depth of the pile has been assumed, and in a special case, it is solved by the attachment of the surrounding ground. There are parallel seismics and magnetic stiffness methods for determining the depth of the foundation pile.
상기 평행탄성파법은 기초파일을 구성하고 있는 콘크리트와 지반의 탄성파 속도 차이를 이용하여 파일의 깊이를 측정하도록 되어 있으나, 이 방법이 적용되기 위한 전제조건은 탄성파원으로부터 파일까지 탄성파 에너지가 확실히 전파되어야 한다. 그러나 파일 상부의 기초 슬라브의 형태에 따라 이러한 조건이 항상 성립되지는 않으며, 파일과 탐사 시추공 사이의 거리가 1.5 m 이상이 되면 적용이 어렵다는 문제점이 있다.The parallel acoustic wave method is to measure the depth of pile using the difference in the seismic velocity of the concrete and the ground constituting the foundation pile, but the prerequisite for this method is to propagate the seismic energy from the elastic source to the pile. do. However, this condition is not always established according to the shape of the foundation slab on the upper part of the pile, and there is a problem that it is difficult to apply when the distance between the pile and the exploration borehole is 1.5 m or more.
상기 자기경도법은 일정한 속도로 움직이는 수직 코일을 이용하여 기초파일 내에 배근되어 있는 철근의 지자기장에 의한 유도 자기장의 시간적 변화량을 측정하여 파일의 선단을 추정하도록 되어 있으나, 상기 방법은 센서를 일정한 속도로 이동시켜야 하며, 정확한 해석이 어렵다는 문제점이 있었다.In the magnetic hardness method, the tip of the pile is estimated by measuring the temporal change of the induced magnetic field caused by the geomagnetic field of the reinforcing bars in the foundation pile using a vertical coil moving at a constant speed. Should be moved to, there was a problem that the exact interpretation is difficult.
본 발명은 상기와 같은 문제점을 고려하여 이루어진 것으로, 그 목적은 파일내에 배근되어 있는 철근의 하부 끝지점 깊이를 용이하게 파악할 수 있는 시추공 내 3-축 자기장 측정에 의한 콘크리트 기초 파일 내의 철근탐지 장치 및 방법을 제공하는 것이다.The present invention has been made in view of the above problems, and an object thereof is to detect a rebar in a concrete foundation pile by measuring a three-axis magnetic field in a borehole, which can easily grasp the depth of the lower end point of the reinforcing steel bars in the pile; To provide a way.
본 발명은 교각이나 대형 구조물의 기초파일에 평행하게 공을 시추하고, 상기 시추공내로 3-축 자기장 측정센서를 삽입하며, 상기 3-축 자기장 측정센서를 탐사 시추공내에서 상하로 이동하여 기초 파일내 철근의 유도 자기장을 측정함과 동시에 상기 3-축 자기장 측정센서의 깊이를 측정하고, 상기 철근의 유도 자기장 측정치와 3-축 자기장 측정센서의 깊이를 컴퓨터에 저장하여 기초파일의 하단 깊이를 측정하는 시추공 내 3-축 자기장 측정에 의한 콘크리트 기초 파일 내의 철근탐지 장치 및 탐지 방법을 제공함에 있다.The present invention drills a ball parallel to the foundation pile of a piers or large structures, inserts a three-axis magnetic field sensor into the borehole, and moves the three-axis magnetic field sensor up and down within the exploration borehole to allow the The depth of the 3-axis magnetic field measuring sensor is measured at the same time as measuring the induced magnetic field of the reinforcing bar, and the depth of the base pile is measured by storing the depth of the induced magnetic field and the 3-axis magnetic field measuring sensor of the reinforcing bar on a computer. An object of the present invention is to provide a detecting device and a method for detecting rebar in a concrete foundation pile by measuring a three-axis magnetic field in a borehole.
도 1 은 시추공 내 3-축 자기탐사법의 모식도1 is a schematic diagram of a three-axis magnetic probe in a borehole
도 2 는 시추공 내 3-축 자기 탐사 장치(K-BH3DMAG)의 개념도2 is a conceptual diagram of a three-axis magnetic probe (K-BH3DMAG) in the borehole
도 3 은 임의 방향의 자기쌍극자에 의한 유도자기장 계산에 필요한 변수 설명도3 is an explanatory diagram of variables required for induction magnetic field calculation by magnetic dipoles in arbitrary directions;
도 4 는 수직 자기쌍극자에 의한 유도 자기장의 수직성분의 분포Fig. 4 shows the distribution of the vertical component of the induced magnetic field by the vertical magnetic dipole.
도 5 는 교각 부근에서의 탐사 결과도5 is an exploration result diagram near the piers
* 도면의 주요 부분에 대한 부호의 설명* Explanation of symbols for the main parts of the drawings
(1) : 기초파일 (2) : 시추공(1): Foundation pile (2): Borehole
(3) : 3-축 자기장 센서 (4) : 유도자기장(3): 3-axis magnetic field sensor (4): induction magnetic field
(5) : 심도펄스발생기(encoder) (6) : 저역통과 필터(5): Depth pulse generator (6): Low pass filter
(7) : 신호배선반 (8) : 초정밀 전압계(7): Signal board (8): High precision voltmeter
(9) : 컴퓨터 (11) : 철근9: computer 11: rebar
(11`): 수직 자기쌍극자(vertical magnetic dipole)(11`): vertical magnetic dipole
(91) : 모니터(91): monitor
모든 물질은 지자기장에 대하여 반응하며, 그 유도 자기장의 크기(자화강도)는 대자율에 비례한다. 즉, 지자기장의 강도를 H 라 할 때 자화강도 I 는 I=kH 이다. 여기서 k 는 대자율(magnetic susceptibility)이다. 퇴적층의 평균대자율은 5×10-5이고, 우리나라의 주된 기반암인 산성 화성암의 평균대자율은 6.5×10-4이다. 그러나, 기초파일 혹은 구조물(100) 내에 배근되어 있는 철근의 대자율은 최소 10이 넘는 값을 보인다. 즉, 철근의 대자율은 주변 지반이나 암반의 대자율에 비해서 최소 10,000배 이상이 되므로, 단위 부피당 철근에 의한 유도자기장(자화강도)의 크기도 단위 부피당 주변지반이나 암반에 의한 유도자기장의 크기보다 최소 10,000 배 이상이 된다. 즉, 본 발명에서 3-축 자기장측정센서로 측정하는 유도자기장은 대부분 철근에 의한 것으로 생각할 수 있다.All matter reacts to the geomagnetic field, and the magnitude of the induced magnetic field (magnetization intensity) is proportional to the large magnetic field. In other words, when the strength of the geomagnetic field is H, the magnetization intensity I is I = kH. Where k is magnetic susceptibility. The mean mass ratio of the sedimentary layer is 5 × 10 -5 , and the average mass ratio of acidic igneous rock, the main bedrock in Korea, is 6.5 × 10 -4 . However, the large susceptibility of the reinforcing bars in the foundation pile or the structure 100 shows a value of at least 10. In other words, the magnetic susceptibility of reinforcing bars is at least 10,000 times higher than that of the surrounding ground or rock, so the size of the induced magnetic field (magnetization strength) by the reinforcing steel per unit volume is also larger than that of the surrounding ground or rock by the unit volume. That's at least 10,000 times. That is, the induction magnetic field measured by the 3-axis magnetic field sensor in the present invention can be considered to be mostly due to rebar.
도 1 은 시추공 내 3-축 자기탐사법의 모식도를 도시한 것으로, 본 발명은 기초파일(1)에 평행하게 공(2)을 시추하고, 상기 시추공(2)내에 3-축 자기장 측정 센서(3)를 삽입하여 철근(11)에서 발생되는 유도 자기장(4)을 측정하며, 상기 측정 자료를 이용하여 파일 내에 배근된 철근(11)의 하부 끝지점을 추출하도록 되어 있다.1 shows a schematic diagram of a three-axis magnetic exploration method in a borehole. The present invention drills a ball 2 parallel to a foundation pile 1, and a three-axis magnetic field measurement sensor 3 in the borehole 2. ) To measure the induced magnetic field 4 generated in the reinforcing bar 11, and extracts the lower end point of the reinforcing bar 11 in the pile using the measurement data.
즉, 기초파일(1)내의 철근(11)은 지자기장에 의해서 유도 자기장(4)을 발생하므로, 지자기장에 의해 발생되는 기초 파일 내 철근(11)의 유도자기장을 기초파일(1)에 평행하게 시추한 공(2) 내에서 3-축 자기장측정센서(2)를 상하로 움직이면서 측정한다. 상기 신호는 컴퓨터에 저장됨과 동시에, 3-축 자기장측정센서(3)의 깊이가 심도펄스 발생기(5)를 통해서 계산·저장되어 기초파일(1) 내에 배근된 철근(11)의 하부 끝지점을 추출하도록 되어 있다.That is, since the reinforcing bar 11 in the foundation pile 1 generates the induced magnetic field 4 by the geomagnetic field, the induced magnetic field of the reinforcing rod 11 in the foundation pile generated by the geomagnetic field is parallel to the foundation pile 1. The three-axis magnetic field sensor (2) moves up and down in the drilled hole (2). The signal is stored in the computer and at the same time, the depth of the 3-axis magnetic field sensor 3 is calculated and stored by the depth pulse generator 5 to locate the lower end of the reinforcing bar 11 disposed in the foundation pile 1. It is supposed to be extracted.
도 2 는 시추공 내 3-축 자기 탐사 시스템의 개념도를 도시한 것으로, 시추공(2) 내에 방수처리되어 삽입된 3축 자기장 측정센서(3)로부터 나온 x, y, z 3성분의 신호는 먼저 저역통과필터(6)를 거치며, 상기 3 성분 신호는 신호배선반(7)을 통해서 차례대로 초정밀전압계(8)를 통하고 그 값이 컴퓨터(9)에 차례대로 기록된다. 이때 센서(3)가 위치한 깊이는 심도펄스발생기(10)를 통하여 컴퓨터(9)에 기록되므로, 결과적으로 어떤 한 깊이에서의 자료는 깊이(depth), xcomp, ycomp, zcomp 의 형태로 기록된다.FIG. 2 shows a conceptual diagram of a three-axis magnetic exploration system in a borehole, in which signals of x, y, z three components from the three-axis magnetic field measurement sensor 3 which are waterproofed and inserted into the borehole 2 are first low-passed. Passing through the pass filter (6), the three-component signal is in turn through the high-precision voltmeter (8) through the signal wiring board 7 and the value is sequentially recorded in the computer (9). At this time, the depth at which the sensor 3 is located is recorded in the computer 9 through the depth pulse generator 10, and as a result, data at any one depth is recorded in the form of depth, xcomp, ycomp, zcomp.
따라서, 한 시추공 내에서의 전체자료는 이러한 자료가 측정한 깊이에 따르는 수열 형태가 되고, 이러한 자료는 측정과 동시에 모니터(91) 상에 그래프의 형태로도 나타나게 되므로, 측정 중에도 지하의 대략적인 상태를 추정할 수 있게 된다.Therefore, the entire data in one borehole is in the form of a sequence according to the depth measured by such data, and this data is also displayed in the form of a graph on the monitor 91 at the same time as the measurement, so that the approximate state of the underground during the measurement Can be estimated.
도 3 은 임의 방향의 자기쌍극자에 의한 유도 자기장 계산에 필요한 변수 설명도를 도시한 것으로, 기초파일(1) 내에 배근되어 있는 철근(11)은 수직 자기쌍극자(11`)로 간주할 수 있다. 수직 자기쌍극자(11`)에 의한 유도자기장은 남북을 잇는 자기경도에 대해 대칭이며, 깊이에 따라서는 수직성분이 수평성분보다 민감하게 반응하므로, 본 장치에서는 수직성분에 대한 이론값만을 고려하였다.FIG. 3 shows a parameter explanatory diagram necessary for the calculation of the induced magnetic field by the magnetic dipole in any direction, and the reinforcing bar 11 arranged in the foundation pile 1 can be regarded as the vertical magnetic dipole 11 '. The induced magnetic field by the vertical magnetic dipole (11`) is symmetrical with respect to the magnetic hardness connecting the north and south, and the vertical component reacts more sensitively than the horizontal component depending on the depth. Therefore, only the theoretical value of the vertical component is considered in this apparatus.
즉, 자기쌍극자(11`)가 임의의 방향으로 존재하는 주변의 자기장에 의해 자화되었을 경우의 유도 자기장 수직성분은 다음의 식으로 나타난다.That is, the induced magnetic field vertical component when the magnetic dipole 11 'is magnetized by the surrounding magnetic field present in any direction is represented by the following equation.
[식1][Equation 1]
여기서, Z는 철근과 같은 자기쌍극자에 의한 유도 자기장 수직성분이며, k는 철근의 대자율, S는 기초 파일에 배근되어 있는 철근의 유효단면적, H0는 지자기장의 수평성분, Z0는 지자기장의 수직성분이다.Where Z is the vertical component of the induced magnetic field by a magnetic dipole such as reinforcing bars, k is the large magnetic modulus of the reinforcing bars, S is the effective cross-sectional area of the reinforcing bars in the foundation pile, H 0 is the horizontal component of the geomagnetic field, and Z 0 is It is the vertical component of the magnetic field.
도 4 는 수직 자기쌍극자에 의한 유도 자기장 수직성분의 분포를 도시한 것으로, 상기 식(1)에 의해 구한 이론적인 유도자기장의 수직성분의 분포는 자기쌍극자(기초 파일)의 양단에서 급격한 변화를 보임을 알 수 있다. 즉, 시추공(2)과 자기쌍극자(11`)가 남-북방향으로 배열된 경우, 도 4a와 같이 유도자기장의 양상은 파일의 양단 주변에서 음 혹은 양의 극값을 나타낸다. 또한, 시추공(2)과 자기쌍극자(11`)가 동-서 방향으로 배열된 경우, 도 4b 와 같이 유도자기장의 양상은 파일의 양단 주변에서 각기 음과 양의 극값을 짝으로 나타내고 양단의 위치는 극값의 부호가 바뀌는 지점이 된다. 또한, 시추공(2)과 자기쌍극자(11`)의 거리에 따른 유도자기장의 변화는 거리가 멀어질수록 이상반응의 크기가 감소되고 극값의 폭이 넓어지는 양상을 보인다.Fig. 4 shows the distribution of the vertical component of the induced magnetic field by the vertical dipole, and the distribution of the vertical component of the theoretical induced magnetic field obtained by Equation (1) shows a sharp change at both ends of the magnetic dipole (base pile). It can be seen. That is, when the borehole 2 and the magnetic dipole 11 ′ are arranged in the south-north direction, as shown in FIG. 4A, the induced magnetic field shows negative or positive extremes around both ends of the pile. In addition, when the borehole 2 and the magnetic dipole 11 'are arranged in the east-west direction, as shown in FIG. 4B, the induction magnetic field shows pairs of negative and positive poles in pairs around both ends of the pile and positions of both ends. Is the point where the sign of the extreme value changes. In addition, the change in the induced magnetic field according to the distance between the borehole 2 and the magnetic dipole 11` shows that the magnitude of the adverse reaction decreases as the distance increases and the width of the extreme value widens.
도 5 는 교각 부근에서의 탐사 결과도 즉, 기초파일로 시공된 교량의 성능개선공사를 위한 기초자료를 얻기 위하여 교각 옆에 시추한 공(2) 내에서 얻은 현장측정치(A)와 이론치(B)의 비교도를 도시한 것으로, 아래 부분에는 기초파일(C)을 표시하였다.5 is an exploration result near the pier, that is, field measurements (A) and theoretical values (B) obtained in a hole (2) drilled next to the pier to obtain basic data for performance improvement of the bridge constructed as a foundation pile. ) Is shown, and the base file (C) is shown in the lower part.
상기 이론치(B)에는 기초파일(1) 내에 배근되어 있는 철근(11)에 의한 유도자기장(4)과 교각 및 기초 슬라브에 배근되어 있는 철근(도시없음)에 의한 유도 자기장이 함께 들어 있으며, 시추공(2) 상부에서의 이론치(B)와 현장측정치(A) 사이의 차이는 시추공(2) 하부에서의 이론치(B)와 현장측정치(A)의 차이보다 크다.The theoretical value (B) contains the induced magnetic field (4) by the reinforcing bar (11) reinforcement in the foundation pile (1) and the induced magnetic field by the reinforcing bars (not shown) in the piers and foundation slab together, borehole (2) The difference between the theoretical value (B) and the field measurement (A) at the top is greater than the difference between the theoretical value (B) and the field measurement (A) at the bottom of the borehole (2).
즉, 교각과 기초슬라브 내에 배근되어 있는 철근의 공간적인 배치 상황은 기초파일(1) 내에 배근되어 있는 철근(11)의 공간적인 배치 상황보다 훨씬 복잡하므로, 정확한 이론치를 계산하기가 어려우며, 상기 교각과 기초슬라브는 시추공 하부로부터의 거리가 10 m보다 훨씬 크므로 이에 의한 유도 자기장은 기초파일(1)의 하부 끝 근처를 지나는 시추공(2) 내의 지점에까지 영향을 미치지 않는다.That is, since the spatial arrangement of the reinforcing bars arranged in the piers and the foundation slabs is much more complicated than the spatial arrangement of the reinforcing bars 11 arranged in the foundation piles 1, it is difficult to calculate an accurate theoretical value. Since the foundation slab is far greater than 10 m from the bottom of the borehole, the induced magnetic field does not affect the point in the borehole 2 passing near the lower end of the foundation pile 1.
도 5 에 도시된 교각 하부의 설계도 상 깊이는 11.7m(1,170㎝)로, 이 깊이까지 철근(11)이 배근되어 있다. 식 1 에 의해 상기 철근(11)의 유도자기장 수직성분 이론치(B)를 산출하면 상기 이론치(B) 곡선은 깊이 11.7m에서 변곡점(D)을 보인다. 또한, 본 발명의 3-축 자기장 센서(3)에 의해 교각 옆에 시추한 공(2) 내에서 얻은 현장측정치(A) 곡선에서도 동일 깊이에 변곡점(D)이 보임을 알 수 있다. 이러한 변곡점(d)의 위치는 기초파일(1)의 깊이가 얕을수록 교각과 상부 슬라브 내에 배근되어 있는 철근의 유도 자기장이 영향을 미치므로 변곡점의 정확한 위치를 찾아내기가 어려우나, 깊이가 클수록 더욱 뚜렷이 나타나게 된다.The design depth of the lower part of the piers shown in FIG. 5 is 11.7 m (1,170 cm), and the reinforcing bars 11 are arranged to this depth. When the theoretical value B of the induced magnetic field vertical component of the reinforcing bar 11 is calculated by Equation 1, the theoretical value B curve shows an inflection point D at a depth of 11.7 m. In addition, it can be seen that the inflection point D is seen at the same depth even in the field measurement curve A obtained in the hole 2 drilled by the pier by the three-axis magnetic field sensor 3 of the present invention. The location of the inflection point (d) is difficult to find the exact position of the inflection point because the shallower the depth of the foundation pile (1) affects the induced magnetic field of the reinforcing bars in the bridge piers and the upper slab, but the higher the depth It becomes apparent.
즉, 상기 이론치(B) 곡선과 현장측정치(A) 곡선의 비교도에서 알 수 있듯이, 3-축 자기장 센서(3)에 의해 측정된 현장측정치(A) 곡선의 변곡점(D)이 나타나는 깊이(11.7m)가 기초파일(1) 하단의 깊이가 된다.That is, as can be seen from the comparison between the theoretical value (B) curve and the field measurement value (A) curve, the depth at which the inflection point (D) of the field measurement value (A) curve measured by the 3-axis magnetic field sensor 3 appears ( 11.7m) is the depth of the bottom of the foundation pile (1).
미설명 부호 (200)은 지반, (300)은 암반, (400)은 지자장이다.Reference numeral 200 is the ground, 300 is the rock, 400 is the geomagnetic field.
이와 같이 본 발명은 측정 물리량이 유도자기장 자체이기 때문에 측정센서의 속도를 일정하게 유지할 필요가 없으며, 원하는 속도로 측정할 수 있다.As described above, in the present invention, since the measured physical quantity is the induction magnetic field itself, it is not necessary to keep the speed of the measuring sensor constant and can be measured at a desired speed.
또한, 본 발명은 자체 생성하는 소스(source)가 없고, 목표물 자체가 생성하는 물리량을 측정하므로 시추공과 파일 사이에 투자율이 높은 철근 등이 없는 어떤 경우에라도 적용할 수 있다.In addition, the present invention can be applied to any case in which there is no source generated by itself and the physical quantity generated by the target itself is not included in the high permeability rebar between the borehole and the pile.
또한, 측정 물리량인 철근에 의한 유도자기장의 크기는 철근의 전체 부피에 비례하고 파일 내에 배근되어 있는 철근은 굵고 수가 많으므로, 본 발명은 시추공과 파일 사이의 거리가 평행탐사법의 최대 적용거리 1.5 m 보다 큰 경우에도 작동 가능하다.In addition, since the size of the induced magnetic field by the reinforcing bar, which is the measured physical quantity, is proportional to the total volume of the reinforcing bar, and the reinforcing bars in the pile are thick and many, the present invention provides a distance between the borehole and the pile of 1.5 m for the maximum application distance of the parallel probe. It can work even larger.
또한, 철근의 하부의 깊이를 추출하여 파일 내의 철근이 설계도대로 배근되었는지를 확인할 수 있으므로, 시공 후의 감리에 이용될 수 있는 등 많은 효과가 있다.In addition, since the depth of the bottom of the reinforcing bar can be extracted to check whether the reinforcing bar in the pile according to the design drawings, there are many effects such as can be used for supervision after construction.
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Cited By (5)
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| KR100563542B1 (en) * | 2003-12-23 | 2006-03-28 | 지하정보기술(주) | Deep Foundation Depth Detection Device Using Steel Three-Component Fluxgate Magnetic Field Meter |
| WO2015153289A1 (en) * | 2014-03-29 | 2015-10-08 | Schlumberger Canada Limited | Deep reading electromagnetic logging while driling tool |
| US9746575B2 (en) | 2013-11-25 | 2017-08-29 | Korea Institute Of Geoscience And Mineral Resources | Induction type broadband 3-component borehole magnetic measuring sensor and borehole electromagnetic tomography method using the same |
| US10215878B2 (en) | 2014-03-29 | 2019-02-26 | Schlumberger Technology Corporation | Gain compensated directional propagation measurements |
| KR101993102B1 (en) | 2018-12-14 | 2019-09-27 | 이재영 | Shape detection system in concrete foundation file, and method thereof |
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| KR102119871B1 (en) | 2018-11-27 | 2020-06-04 | (주)에이에이티 | Standalone type exploratory sensor management apparatus |
| CN114046751B (en) * | 2021-09-30 | 2024-04-26 | 湖南天功测控科技有限公司 | Foundation pile rock-socketed depth detection method based on directional acoustic wave method |
| CN118327066B (en) * | 2024-06-13 | 2024-08-20 | 上海勘测设计研究院有限公司 | Flood control wall foundation detection method |
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| US4372398A (en) * | 1980-11-04 | 1983-02-08 | Cornell Research Foundation, Inc. | Method of determining the location of a deep-well casing by magnetic field sensing |
| US5485089A (en) * | 1992-11-06 | 1996-01-16 | Vector Magnetics, Inc. | Method and apparatus for measuring distance and direction by movable magnetic field source |
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| US4372398A (en) * | 1980-11-04 | 1983-02-08 | Cornell Research Foundation, Inc. | Method of determining the location of a deep-well casing by magnetic field sensing |
| US5485089A (en) * | 1992-11-06 | 1996-01-16 | Vector Magnetics, Inc. | Method and apparatus for measuring distance and direction by movable magnetic field source |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100563542B1 (en) * | 2003-12-23 | 2006-03-28 | 지하정보기술(주) | Deep Foundation Depth Detection Device Using Steel Three-Component Fluxgate Magnetic Field Meter |
| US9746575B2 (en) | 2013-11-25 | 2017-08-29 | Korea Institute Of Geoscience And Mineral Resources | Induction type broadband 3-component borehole magnetic measuring sensor and borehole electromagnetic tomography method using the same |
| WO2015153289A1 (en) * | 2014-03-29 | 2015-10-08 | Schlumberger Canada Limited | Deep reading electromagnetic logging while driling tool |
| US9541666B2 (en) | 2014-03-29 | 2017-01-10 | Schlumberger Technology Corporation | Electromagnetic logging while drilling tool |
| US9581721B2 (en) | 2014-03-29 | 2017-02-28 | Schlumberger Technology Corporation | Method for making downhole electromagnetic logging while drilling measurements |
| US10215878B2 (en) | 2014-03-29 | 2019-02-26 | Schlumberger Technology Corporation | Gain compensated directional propagation measurements |
| KR101993102B1 (en) | 2018-12-14 | 2019-09-27 | 이재영 | Shape detection system in concrete foundation file, and method thereof |
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