Application of Digital Image Correlation Technology in Geotechnical

Structure Measurement

ZhenZhu Guo

, Lu Wang and Xiaojuan Shi

Tianjin College, University of Science and Technology Beijing, Tianjin, China

Keywords: Digital Images, Civil Structures, Bridge Engineering, Applicability.

Abstract: With the international trend towards digitization and intelligence, traditional geotechnical testing technology

has gradually been replaced by digital image technology. This article focuses on the basic principle of digital

image correlation method, discusses the applicability of this technology in strain measurement of geotechnical

structures in civil engineering and bridge engineering, and discusses the development prospects of this

technology.

1 INTRODUCTION

As an important part of civil engineering

construction, the accuracy of geotechnical

measurement results determines the overall quality of

the project. However, existing testing techniques

often require manual analysis and processing of data,

resulting in low efficiency; The high cost of

machinery and labor used is not conducive to the

formation of scale. With the current international

trend, the production system of digital maps and the

intelligence and digitization of basic urban

information are continuously promoted. At the same

time, surveyors transmit the collected data in real-

time to the network, achieving visual manipulation

and efficient, convenient, and accurate data

transmission. The new demand for measurement

technology has accelerated the replacement of

traditional manual drawing and mechanical

measurement, and the application of digital image

correlation technology in geotechnical structure

measurement has emerged (Cao Lu, 2018).

Digital image related technology was proposed

by scholars in the United States and Japan as early as

the 1980s and has been invested in research and

development. It is a modern optical measurement

technology that integrates full field, three-

dimensional, and non-contact measurements. Due to

its strong adaptability to the external environment,

low susceptibility to light interference, high degree of

mechanical automation, and good operability, it has

been widely applied in various fields such as

bioscience, mechanical simulation, civil engineering,

food safety, etc. In the field of civil engineering

measurement, digital image related technology can be

applied to measure the static displacement of objects

during loading, such as torsion, bending, and tensile

deformation. The accuracy of the results has been

verified by scholars using finite element methods.

2 BASIC PRINCIPLES

Digital image correlation technology, also known as

digital speckle correlation method, mainly consists of

CCD or COMS cameras, lighting sources, image

acquisition cards, and computers (Zhang Shunqing,

2017). It uses a CCD or COMS camera to store the

captured image of the specimen on an image

acquisition card, divides it into regions of interest at the

pixel level through computer processing, and defines

the specimen in each sub region of the region of

interest as a rigid body. A search algorithm is used to

calculate according to the pre-set correlation function,

and the deformed rigid body specimen is compared

with the region of interest to find the region with the

highest correlation coefficient value, and locate the

deformed rigid body specimen, and then calculate the

deformation position of the rigid body specimen.

Figure 1. Schematic diagram of digital image related

technology measurement system.

Guo, Z., Wang, L. and Shi, X.

Application of Digital Image Correlation Technology in Geotechnical Structure Measurement.

DOI: 10.5220/0012284100003807

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 2nd International Seminar on Artiﬁcial Intelligence, Networking and Information Technology (ANIT 2023), pages 367-369

ISBN: 978-989-758-677-4

367

2.1 Application of Digital Image

Correlation Method in Bridge

Crack Deformation Monitoring

Monitoring

In bridge engineering, due to long-term external loads

such as vehicle loads on the beam structure, cracks

can easily occur over time, which can lead to

insufficient bearing capacity of the bridge structure.

Therefore, timely detection of cracks on the bridge

structure can help workers prevent accidents and

reduce the occurrence of dangerous accidents.

According to the specifications of ACI and CBE, the

allowable width of transverse cracks in bridge

structures is 0.2mm, which is more stringent in areas

with corrosion hazards. The allowable width defined

as transverse cracks is 0.1mm; At the same time,

longitudinal cracks are not allowed to appear in the

beam structure of the bridge. For cracks and other

deformations on the bridge beam structure, the

electrical measurement method is usually used, which

selects points for the bridge beam structure and

measures the strain at representative points. However,

this method is difficult to measure the strain at the mid

span of the bridge, and when measuring deformations

with minimal deformation, using a magnifying glass

cannot meet the accuracy requirements. Therefore,

non-contact digital image correlation technology was

used in the measurement of cracks in bridge beam

materials. In operational engineering, the field of

view of the digital camera was adjusted to 102.64. *

82.09, and the calibration result was 0.0802 pixel at

the pixel level. By intercepting the deformation area

of 30 * 30 pixel in DIC software and comparing the

displacement difference between the two areas, it was

found that digital correlation technology has

superiority and feasibility in measuring the

deformation properties of bridge beam structures

under dynamic and static loads (Bai Xiaohong, 2011).

Figure 2. Measurement process of strain points in bridge

structures (Wang Jing, 2003).

2.2 Application of Digital Image

Correlation Method in Rock

Microscopic Material Monitoring

In civil engineering, whether natural geotechnical

materials or artificial materials, there is heterogeneity

within them. This non-uniformity will lead to uneven

strain in the structure under external loads, resulting

in cracks in geotechnical structures constructed from

geotechnical or synthetic materials (airport taxiways,

large embankment supports, highway pavements),

leading to a decrease in their mechanical

performance. However, the detection of the

aforementioned geotechnical structures faces

challenges such as large monitoring areas and limited

selection of detection methods. Usually, traditional

sensors cannot solve problems such as cracks on

highways, and laser, radar, ultrasound, and other

technologies are used to solve them. However, if non-

contact detection of the object being tested is

required, digital image processing technology will

emerge. It uses DIP technology to analyze the image

situation and further detect the bedding structure of

concrete materials in geotechnical structures, Further

research will be conducted on the mechanical and

physical properties of rock and soil materials such as

concrete.

2.3 Application of Digital Image

Correlation Method in Weld

Strength of Materials Performance

Detection

Similar to rock materials, weld material is also a non-

uniform material, which is affected by different

materials, temperatures, and construction processes,

resulting in different mechanical properties;

Therefore, it is very important to conduct quantitative

research on weld material in different regions. With

the growing use of DIC, many scholars have applied

digital image correlation technology to the weld

research of base metal. They take TC4 titanium alloy

as the research object, place it in the uniaxial Tensile

testing, and measure the strain field of weld material

under different loads and areas. According to digital

image correlation technology, the experimental

results show that the strain in the base metal area is

much greater than that in the weld seam area and the

affected area, and the base metal area has good

toughness. At the same time, the finite element model

is used to verify the above results, indicating that

using digital correlation technology can effectively

detect the mechanical properties of the weld seam

ANIT 2023 - The International Seminar on Artiﬁcial Intelligence, Networking and Information Technology

368

material, with high accuracy and good measurement

reliability (Hang Chao, 2013).

2.4 Applied to Damage Observation

and Fatigue Assessment of Steel

Components

Steel structural materials have the advantages of light

weight, short construction period, strong seismic

performance, and easy transportation, and are

currently highly praised by domestic and foreign

countries. With the vigorous promotion of steel

structures and prefabricated installation methods,

more and more building forms are constructed using

steel structures, such as steel residential buildings,

steel bridges, etc. It can be seen that the usage of steel

structures is increasing day by day. Therefore, the

damage and fatigue assessment of steel structural

components will play a very important role in the

operation of steel structural components, and have

very good development prospects. Traditionally, the

methods for damage and fatigue testing of steel

structural components have low efficiency, are prone

to blind spots in the detection process, and

measurement instruments are relatively expensive.

With the continuous fermentation of image

recognition technology, operations based on digital

image related technologies have emerged. Before the

experimental operation, the specimens need to be

divided into base metal and weld metal specimens. A

fatigue testing machine is used to cyclically load the

specimens, with a minimum loading setting of 10kN.

Optical calibration equipment is used to calibrate the

loaded specimens to form speckle. The fatigue

performance of the base metal or weld material of the

steel structure specimen is determined by comparing

the three-dimensional displacement parameters and

three-dimensional strain parameters of the speckle.

The experimental results indicate that this method has

a certain degree of predictability and can help

technicians detect fatigue signals of steel structural

materials in advance, providing effective support for

the study of residual bearing capacity of steel

structural components (Yang Yuntao, 2022).

3 CONCLUSION AND OUTLOOK

Digital image related technology is a widely used

technology with good development prospects and

advantages. It has good measurement stability in civil

engineering materials and bridge engineering, and its

future development trend will continue to develop

towards intelligence, wide applicability, high

precision, high efficiency, Technological

convergence and other aspects, bringing more

benefits to mass industrial production and life; At the

same time, there are still urgent problems to be solved

in digital image related technologies, including

further overcoming challenges in low-quality image

processing, multimodal image processing, privacy

protection, and other aspects.

Of course, in addition to the above, there are also

many material measurements using DIC technology,

such as internal deformation of pipelines (Xiangjun

Dai, 2023) and fatigue cracks. As well as rock cracks

under high water pressure (Yun Tian, 2023), it can be

seen that digital correlation technology (DIC) has

applicability in various fields of engineering and is

still worth further exploration.

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