charactreistics of labor accidents caused by...

3 Project title Kwasa Damansara Township

Location Sungai Buloh, Selangor

Scale Regional

Area 2,330 acres

SUDSComponents

Bio-ecological swales, bio-retention, bio-engineered channel, gross pollutant trap(GPT), on-site detention (OSD), sedimentforebay, detention pond, constructedwetlands

VI. CONCLUSION

In the past decade, water related crisis such asflash flood, water scarcity and water pollution hascaused socio-economic losses to the people inMalaysia. The concept of sustainable urbanstormwater management is based on formulatingdevelopment plans that incorporate an integratedapproach to the management of the urban water cycle.The primary goal is to minimise the impact ofurbanisation of the stormwater environment and tostrike a balance between social, economic andenvironmental concerns to achieve sustainabledevelopment. This paper reveals the contributionSUDS can participate with in the rehabilitation ofvarious scale of development projects. In relation tostormwater management, SUDS involves a pro-activeprocess which recognises the opportunities for urbandesign, landscape architecture and stormwatermanagement infrastructure to be intrinsically linked.SUDS can be applied at large scales to serve a regionor a catchment area. The challenge ahead is tocontinue the SUDS holistic planning and designapproach to urban stormwater management and toprovide technically robust solutions that excite andengage communities to deliver improvedenvironmental outcomes for today and futuregenerations.

ACKNOWLEDGMENT

The authors would like to acknowledge thefinancial assistance from Ministry of EducationMalaysia under HICoE’s niche area of SustainableUrban Stormwater Management (Grant No.311.PREDAC.4403901).

REFERENCES

1. DID, Urban Stormwater ManagementManual for Malaysia (MSMA). 2000,

Department of Irrigation and Drainage,Malaysia: Kuala Lumpur.

2. DID, Second Edition of Urban StormwaterManagement Manual for Malaysia (MSMA2nd Edition). 2011, Department of Irrigation

and Drainage, Malaysia: Kuala Lumpur.3. CIRIA, The SUDS Manual. 2017,

Construction Industry Research andInformation Association, UK: London.

4. CIRIA, The SUDS Manual. 2007,Construction Industry Research and

Information Association, UK: London.5. Zakaria, N.A., Ab. Ghani, A., Abdullah, R.,

Mohd Sidek, L. & Ainan, A., Bio-EcologicalDrainage System (BIOECODS) For Water

Quantity And Quality Control, InternationalJournal River Basin Management, 2003,

1(3): p. 237-251.6. Ab. Ghani, A., Zakaria, N.A., Abdullah, R.,

Yusof, M. F., Mohd Sidek, L., Kassim A.H.& Ainan, A., “Bio-Ecological Drainage

System (BIOECODS): Concept, Design andConstruction”. in Proc. of The 6th

International Conference on Hydroscienceand Engineering (ICHE-2004), Brisbane,

Australia. 2004.7. Chang, C.K., Zakaria, N.A., Ab. Ghani, A.

& Goh, H.W. Securing Water for FutureGenerations through Sustainable UrbanDrainage Design and Management: Bio-

ecological Drainage System (BIOECODS) -Malaysian Experiences. The Magazine of

The Chinese Institute of Civil & HydraulicEngineering. 2018, 45(6): 41-52.

8. McAuley, A. & McManus, R. WaterSensitive Urban Design Planning Guide -

Prepared for: Northern Territory Departmentof Planning and Infrastructure. 2009.

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61KECConference2019, Kantipur Engineering College, Dhapakhel Lalitpur

CHARACTREISTICS OF LABOR ACCIDENTS CAUSED BY SLOPE FAILURE

DURING SLOPE CUTTING WORKS AND APPLICATION OF TILT SENSOR FOR

MEASUREMENT OF SLOPE MOVEMENT

Kazuy ITOH Dept. of Urban and Civil Engineering

(Associate Professor) Tokyo City University

Tokyo, Japan [email protected]

Naotaka KIKKAWA Construction Safety Reserch Groupe

(Senior Researcher) National Institute of Occupational

Safety and Health, Japan (JNIOSH) Tokyo, Japan

[email protected]

Tatsuya SHIBATA Dept. of Geological Survey

Kensetsu Consultant Center Co., Ltd. Shizuoka, Japan

[email protected]

Surendra B. TAMRAKAR Civil Engineering Dept./ RTCD

(Associate Professor/ Chief) Kantipur Rngineering College

Tribhuvan University Dhapakhel, Lalitpur, Nepal

[email protected]

Nobutaka HIRAOKA Construction Safety Reserch Groupe

(Researcher) National Institute of Occupational

Safety and Health, Japan (JNIOSH) Tokyo, Japan

[email protected]

Yasuo TOYOSAWA Advanced Research Laboratories

(Visiting Professor) Tokyo City University

(formar director of JNIOSH) Tokyo, Japan

[email protected]

Abstract— Sudden failure of slope during or just after the slope cutting works causes many accidents which sometimes takes the lives of workers. Lives of the workers and properties could be saved if early predictions of failure could be made. Many instruments have been developed to measure the movement of slope just before the failure. But most of them are either difficult to set up in the real field or are expensive to opt. In this paper, the characteristics of labor accidents caused by slope failure during slope cutting works in Japan are explained firstly. Then, the guideline for prevention of labor accidents caused by slope failure during slope cutting works is summarized. Finally, a case history of field measurement during slope cutting and nailing slope works is introduced.

Keywords—labor accidents due to slope failure, monitoring, field measurement

I. INTRODUCTION Mountains and hilly terrain account for 70% or

more of Japanese national land area. Japan is located in one of the world's premier mobile belts and in the past, intense crustal disturbances had taken place, which formed precipitous features with weak and complicated geological structures. Moreover, the

feature of Japanese climate, such as rainy seasons, typhoons with localized severe rain, and freeze-thawing in cold districts, could make landslides, cliff failures, rock falls, and avalanches of rocks and earth more likely to occur. However, the main transportation networks of railways and roads run below steep slopes in mountain areas or along the coastline, and urban development reaches the hilly zones and the bases of mountains. In addition, many houses are constructed close to slopes and cliffs. Under severe circumstances, such advanced and over-concentrated land usage poses risks of slope failure accidents.

There are two main causes of slope failure: 1) natural phenomena such as torrential rain or earthquakes, and 2) human-induced construction works. Human-induced causes lead to the labor accidents that take the lives of construction workers. Most of the accidents are either fatal or serious. Accidents involving death of workers are termed as fatal and those involving at least two worker casualties are termed as serious. Figure 1 illustrates the annual death toll of labor accidents caused by slope failure along with that of the whole construction industry and "Land collapses or Sliding debris, etc.". The annual number of fatal accidents in the whole construction industry had been constantly at around 1000 and gradually decreased since 1996. As for the target accidents of this paper, the number had fluctuated at

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between 20 and 30 (except for 1992) until 1995 and decreased since 1996, which corresponds to the tendency of the whole construction industry.

When construction works are conducted for stabilizing the slope, there is a risk of slope failure. Most of the slope failures occur due to destabilization of a slope when the lower part of a natural slope is removed or a part of the slope is steepened during construction work, specifically during the slope-cutting work. In addition, no clear signal appears before slope failure, which leads to labor accidents. In many cases, slope failure occurs so suddenly [1],[2] that the workers have no time to evacuate from such sites and eventually casualties occur. However, it is possible to prevent such labor accidents caused by slope failure during construction works by taking elaborate measures in each phase of the construction, including planning, designing, and implementation. This is because most of such accidents are caused by man-made factors.

In this paper, the characteristics of labor accidents caused by slope failure during slope cutting works in Japan are explained firstly. Then, the notification from government named “Guideline for prevention of labor accidents caused by slope failure during slope cutting works” issued by Ministry of Health, Labor, and Welfare (MHLW), Japan in 2015, is summarized. After that, one of this monitoring methods where tilt sensors are used for the measurement of early response of failure just before the failure, is explained. Finally, a case history of field measurement during slope cutting and nailing slope works is introduced.

II. CHARACTERISTICS OF LABOR ACCIDENTS CAUSED

BY SLOPE FAILURE DURING SLOPE CUTTING WORKS

Various studies have been conducted on the characteristics of labor accidents caused by slope failure during slope cutting works in Japan. The first report of survey data of labor accidents in Japan was that of Mae et al. [3], who proposed that it is necessary to investigate the actual conditions (workers, environment, geology, etc.) of these

accidents. Since then, classifications of various factors using labor accident data have been carried out by Itoh et al. [4], [6] and Toyosawa et al. [5]. Some important information is extracted from the survey results reported by Itoh et al. [4] and introduced in this chapter.

Figure 2 shows the relationship between the number of accidents and that of the workers presented at the time of the accident by bar graph, and a cumulative relative frequency of number of the accidents by line graph. This figure estimated that 84% of the accidents occurred in the construction projects with less than 8 workers on the construction sites. Since the number of workers can be related to the size of the contractor, the accident rate also corresponds to it as well and the possibility of accidents is higher with small-middle-sized contractor. This is probably due to the facts that the small-middle-sized contractors have problems of not only shortage of operation chiefs and/or workers with appropriate knowledge concerning safety and health management but also shortage of budgets for adequate safety equipment. Based on these findings, it can be concluded that the labor accidents are likely to occur in the small-middle-sized construction projects with small budgets and relatively short construction period conducted by the small-middle-sized contractors.

There are mainly two slope stabilizing construction methods which cause slope failure accidents: retaining wall method and slope protection method as shown in Figure 3. According to the investigation conducted by Itoh et al. [4], approximately 73% of the labor accidents occurred during slope stabilization construction works by the retaining wall method. In contrast, the number of accidents that occurred during works using the slope protection method was much smaller (approximately 16%). This is probably caused by the facts that the retaining wall construction generally includes the excavation of steep and unstable slope (Figure 4, [7]),

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Figure 2 Number of workers present at the time of

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Figure 1 Annual number of labor accidents

during construction works.

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and various construction works such as assembling/dismantling of formworks (Figure 5, [7]), smoothing of base and so on have to be carried out in a narrow space between the retaining wall and the excavated ground. Therefore, it is too difficult and too little time for workers to evacuate from such narrow working space when slope failure suddenly occurs.

III. GUIDELINE FOR PREVENTION OF LABOR ACCIDETNS COUSED BY SLOPE FAILURE DURING SLOPE CUTTING

WORKS

A. JNIOSH report In 2003, National institute of industrial safety

(Currently known as National Institute of Occupational Safety, Japan, JNIOSH) has started a special research project to investigate the labor accidents caused by slope failure [8]. Based on these results, JNIOSH established the “Commission of inquiry on prevention of labor accidents caused by slope failure” under the leader of Prof. Kusakabe (Tokyo Institute of technology) with external experts as its members, which subsequently met on four occasions to discuss the matter [9]. It concluded that there are three factors to prevent the labor accidents due to slope failure as follows. i) Shearing the Information among employers,

contractors, and designers about labor accident risk assessment.

ii) Examination into the safety of construction site from the viewpoint of labor accident.

iii) Concept of effective construction method to prevent the possibility of labor accident caused by slope failure.

B. Guideline for prevention of labor accidents caused by slope failure during slope cutting works by MHLW, Japan.

After the publication of the JNIOSH report [9],

“Guideline for prevention of labor accidents caused by slope failure during slope cutting works” was issued by Ministry of Health, Labor, and Welfare (MHLW), Japan in 2015. The outline of its chapters is shown in Table 1 [10]. In order to enforce the article 355 and 358 of Ordinance on Industrial Safety and Health (OISH) securely, this guideline was notified. The text of the article 355 and 358 of OISH is shown in Table 2. Making the persons concerned understand the safety of slope cutting works at each construction phase, it shows three types of checklists: design and construction procedures checklist, daily checklist, and ground deformation checklist. Furthermore, there is a troubleshooting sheet to report any trouble information and share it with the persons concerned, if any kind of trouble occurs.

Safety of the slope should be assured throughout the construction process based on the slope monitoring data such as ground deformations obtained from displacement sensors, high precision tilt-sensors, etc. Failsafe measures must be included in measuring and warning systems. Although many instruments for monitoring landslides have been developed to measure the movement of the slope just before failure, most of them are either too difficult to be set up at the construction site or too expensive for small-to-medium-scale slope cutting projects. Nowadays, however, many attempts are being made to develop new applications using the latest technologies such as sensing, computing, and communication technologies by Uchimura et al. [11], [12], Sawada et al. [13], Nishiyama et al. [14], etc. Flexible and innovative designs for monitoring and early warning systems for landslide disasters have been realized by providing accurate, low-cost, and low-power-consumption wireless equipment.

Retaining wall method89

(72%)

Slope protection method19

(15%)

Others15

(12%)

Figure 3 Classification of slope failure accidents by

construction methods [4]

Figure 4 Accident site at concrete frame construction work [7]

Figure 5 Accident site at frame dismantling work [7]

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IV. CASE HISTORY OF MONITORING DURING SLOPE CUTTING WORKS USING HIGH PRECISION TILT SENSORS

A. Specication of field site The site, shown in Figure 6, located in Shizuoka

Prefecture, Japan, was for the project of restoration works for the road damages and the slope failure caused by the heavy rain in 2018. A top-down slope stabilization method was used for the project, which is one of the effective construction methods to prevent the possibility of slope failure and protection materials for the method are short reinforcing steel bars and shotcrete which can be obtained at lower costs than those for the ground anchor method.

B. Methodology Two types of measuring instruments were used

for the project: one wire extensometer and two high precision tilt sensors. A wire extensometer (sensitivity of 0.1mm, SLG-100A, OSASI Technos Inc.) was used to measure the deformation of slope surface. A high precision tilt sensor (IT tilt sensor, AKEBONO Brake Industry Co., Ltd) was equipped with a MEMS tilt sensor as shown in Figure 7. This is used to measure positive and negative angles in both X and Y directions angles. Its measuring range was ±20 degrees with sensitivity of 1/100 degrees. The tilt sensors were placed along the cross section of the site and installed on the single pipes mounted in the holes made by hand augering to a depth of 0.5m. he data logger, powered by three double A (AA) battery, recorded the data at 1 min interval.

Excavation and protection were alternately carried out on the slope in steps to be stabilized from the top to the bottom. Table 3 shows the excavation and the nailing phases under the construction.

TABLE 1 OUTLINE OF CHAPTERS OF GUIDELINE [11]

Chapter Contents 1 Aim and objective of this guideline 2 Scope of application 3 Definition of term 4 Necessity in cooperation with employer,

contractor, and designer 5 Points to consider regarding designer 6 Points to implementation regarding contractor

TABLE 2 ARTICLE 355 AND 358 OF OISH, JAPAN.

Ordinance on Industrial Safety and Health (Investigation on Work Place, etc.)

[Article 355] The employer shall, in the case of carrying out an excavating work of natural ground, and when it is liable to endanger workers due to collapse of natural ground, broken underground-installed objects, etc., investigate in advance the natural ground of the work place and its surroundings as to the following matters by boring or other suitable methods, and determine the time and procedures of excavation on the in conformity with what is known by the investigation and carry out by the determinations thereof: (i) Landform, nature of the soil and conditions of strata. (ii) Existence and conditions of cracks, water content,

spring water and freezing. (iii) Existence and conditions of underground-installed

objects, etc. (iv) Existence and conditions of high-temperature gas

and vapor. (Checkup) [Article 358] The employer shall, when carrying out the

work of open-cut excavation, take the following measures to prevent workers from dangers due to collapse of natural ground or fallen earth and rocks:

(i) To designate a checker and have the said checker carry out a checkup on the natural ground of the work place and its surroundings before commencing the work for the day, after a heavy rain and an earthquake of medium shock or heavier as to the existence and conditions of loose stones and cracks, and changes in water content, spring water and freezing.

(ii) To designate a checker and have the said checker carry out a checkup on the existence and conditions of loose stones and cracks, after blasting operations, at places where the said blasting operations have been carried out and their surroundings.

Figure 6 installation of this site

Figure 7 IT tilt sensor (AKEBONO Brake Industry Co., Ltd)

TABLE 3 EXCAVATION AND NAILING PHASES DURING THIS CONSTRUCTION

Event Date Excavation 1st stage 5/10/2019

Nailing 1st stage 5/25/2019 Nailing 2nd stage 5/25/2019-5/28/2019 Nailing 3rd stage 5/31/2019

Excavation 2nd stage 6/7/2019 Nailing 4 stage 6/20/2019 Nailing 5 stage 6/25/2019

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C. Tilting behaviour A wire extensometer did not record a slope

movement during the construction. Figure 8 shows the time history of two tilt sensors including some main events: excavation, nailing, rainfall, etc. Figure 9 shows the photos during and before the construction in this field monitoring site. Movements of X and Y directions were measured by each sensor. A quick tilting in the X and Y directions were recorded on May 21 when the precipitation was 236.5mm. Related to some events such as excavation and nailing (slope protection), gradual change was observed in the tilting angles. Direction of slope movement during various events could be measured by observing the very little movement: sensitivity of 1/100 degrees of tilt sensors along X and Y directions.

Safety of slope can be assured throughout the construction process based on the slope monitoring.

V. CONCLUSIONS

In this paper, we described the characteristics of labor accidents caused by slope failure during slope cutting works in Japan, and the notification from government named “Guideline for prevention of labor accidents caused by slope failure during slope cutting works.” Then, a case history of field measurement during slope cutting and nailing slope works was introduced. As a result, the following conclusions were drawn from this study:

i) 73% of the labor accidents occurred during slope stabilization construction works by the retaining

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with human body or nailing machine

Figure 8 Time history of two tilt sensors and records of rainfall

Excavation 1st stage

Nailing 3rd stage

Naring 4th stage

Figure 9 Excavation and nailing phases during this construction

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wall method. The main reasons are that the working space was so narrow when conducting this method and the slope failures occurred so suddenly, that there were neither route nor time for the workers to evacuate from the construction site.

ii) In order to make the persons concerned understand the safety of slope cutting works at each construction phase, MHLW, Japan issued the guideline for prevention of labor accidents caused by slope failure during slope cutting works in 2015, where three types of checklists were introduced: design and construction procedures checklist, daily checklist, and ground deformation checklist.

iii) A case history of field measurement during slope cutting and nailing slope works was introduced. Direction of slope movement during various events could be measured by observing the very little movement: sensitivity of 1/100 degrees of tilt sensors along X and Y directions. Safety of slope can be assured throughout the construction process based on the slope monitoring.

ACKNOWLEDGMENTS

About field measurement, we wish to thank Mr. Nishijyo of AKEBONO Brake Industry Co., Ltd. for his helpful support.

REFERENCES

[1] Takei, A. (1980) Landslide, slope failure, mudflows - forecast and counter-measures. Kajima Institute Publishing Co., Ltd., p.25 (in Japanese).

[2] Okuzono, S. (1986) 100 points for prevention of slope failure. Kajima Institute Publishing Co. Ltd., p.6 (in Japanese).

[3] Mae, I., Suzuki, Y. and Horii, N. (1978) Analysis of fatal accidents caused by slope-failure and rock-fall in the cutting work sites. Safety Document of National Institute of Industrial Safety, RIIS-TN-78-1, pp. 19 (in Japanese).

[4] Itoh, K., Toyosawa, Y., Tamrakar, S., B., Horii, N. (2005) Analysis of labor accidents caused by slope failure, Journal of the Japan Landslide Society : Landslides, Vol. 41, No. 6, pp. 585-594 (in Japanese).

[5] Toyosawa, Y., Itoh, K., Tamrakar, S.B., and Horii, N. (2005). The Characteristics of Labor Accidents Caused by Slope Failure. The International Symposium on Landslide Hazards in Orogenic Zone from the Himalaya to Island Arcs in Asia, pp.281-290.

[6] Itoh, K., Kikkawa, N., Toyosawa, Y. (2015) Analysis of Labor Accidents caused by Slope Failure during slope cutting work, Japan Domestic Conference on Geotechnical Engineering, Vol. 50, pp. 2195-2196 (in Japanese).

[7] Toyosawa, Y., Itoh, K., Kusakabe, O., Takemura, J., Takahashi, A., Izawa, J. (2009) Preventive Strategy for Labor Accidents Caused by Slope Failures, Proceeding of Asia Pacific Symposiumm on Safety 2009, pp. 139-142.

[8] National Institute of Occupational Safety and Health, Japan (2007) Safety for Construction of Small-to-medium Sized Excavation Using Observational Procedure, Specific Research Report of National Institute of Occupational Safety and Health, JNIOSH-SRR-No.35 (2007), 149p, (in Japanses) https://www.jniosh.johas.go.jp/publication/srr.html#srr2007

[9] National Institute of Occupational Safety, Japan (JNIOSH) (2010) Report of Commitions of Inquiry on Prevention of Labor Accidents caused by Slope Failure, (in Japanses) https://www.jniosh.johas.go.jp/publication/houkoku/houkoku_2010_01.html

[10] Minisotry of Health, Labour and Welfare, Japan (2015) Guideline for Preventation of Labor Accidents cause by Slope Failures during Slope Cutting Works, (in Japanses) https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/0000149406.html

[11] Uchimura, T., Towhata, I., Wang, L., Seko, I. (2009) Developemnt of low-cost early warning system of slope instability for civilian use. Proceedings of the 17th ISSMGE, Alexandria, Vol. 3, pp. 1897-1900.

[12] Uchimura, T., Towhata, I., Wang, L., Nishie, S., Yamaguchi, H., Seko, I., Qiao, J. (2015) Precution and early warning of surface failure of slope using tilt sensors, Soils and Foundations, Vol. 55, No. 5, pp. 1086-1099.

[13] Sawada, M., Shiba, Y., Saeki, M. (2012) Development of a GPS wireless sensor system for monitoring gournd displacemnet, Proceedings of the International Workshop on ICT in Geo-Engineering, Kyoto, pp. 89-97.

[14] Nishiyama, S., Yano, T., Ohnishi, Y., Sato, M., Nakagawa, M. (2012), Realtime displacemnet measurement method using phase differences of radio waves, Proceedings of the International Workshop on ICT in Geo-Engineering, Kyoto, pp. 251-258.

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System development of moiré camera array for displacement and strain measurement Rujika Tuladhar

MSc. Structural Engineering, School of Engineering and Technology, Asian Institute of Technology

Kathmandu, Nepal [email protected]

Dr. Punchet Thammarak Senior Lecturer, School of Engineering and Technology,

Asian Institute of Technology Pathumthani, Thailand

[email protected]

Abstract—The available conventional sensor like displacement transducer used in Structural Engineering laboratory is expensive. In addition to that, the need of data acquisition device also escalates the expense invested for point contact measurement system. The recent appeal of vision-based measurement technique and search for cost-effectiveness has led to exploration of the established sampling moiré method using cheap CCTV cameras as a viable option. The sampling moiré method is simple and analyzes the displacements from grating images by phase shifting method. A series of trial experiments that were conducted, which demonstrated that the setup is at least as accurate as the more traditional measuring system. An experiment was conducted in a steel I-beam for displacement measurement which has displayed satisfactory result. In addition, the setup was also tested for strain measurement and it has yielded promising result that needs fine tuning. This thesis discusses the challenges, findings and possibility of incorporating vision-based displacement measurement in laboratory platform.

Keywords— Vision-based measurement, Sampling moiré

method, CCTV camera, image processing, displacement and strain

I. INTRODUCTION Vision-based measurement systems present to us fascinating proposition which features simple instrumentation and installation along with remote access yet whole field measurement using a single (camera) sensor. The traditional deformation measurement technologies such as LVDT, strain gage, etc. necessarily require physical access to a structure and are suitable for point measurements only. This interference has led vision-based methods to garner great research interest in recent times [1].

The use of the principle of sampling moiré method [2] for the applicability to the laboratory platform has been explored here. Studies available on the performance of the sampling moiré method are primarily focused on comparing how well the computer simulation [3] [4] and experiments conducted [5] [2] agree with those obtained by displacement sensor. They have highlighted the fact that the method is simple and easy procedure with high accuracy and analysis speed in addition to low-cost performance [6] [7]. There has been development of

the sampling moiré camera for small displacement detection for close-range and long-range displacement measurement [8], which is compact and high resolution but expensive.

Moiré camera is a vision-based, non-contact measurement device in order to analyze the captured images of gratings by image processing technique to measure displacement and strain values in structures. This study focuses to address the implementation and augment the usability of the method for laboratory scale. Several laboratory trials were conducted to characterize the influential factors such as target distance from camera, optimal grating size on measurement performance. This was established by verifying the performance of the sampling moiré method using CMOS sensor-Mars series and then using the scheme for CCTV camera, platform for trials later to be deployed to specimen testing.

The implementation of this scheme could open new doors to supersede the functionality of traditional technology which are otherwise expensive. For example, the cost of the displacement transducer alone is 50K Baht excluding the cost of data logger. Even if 12 units of CCTV cameras, each costing around 2K Baht was used, the overall setup would cost us around 35K Baht. This experiment seeks to make use of vision-based measurement technique and find displacement and strain simultaneously.

II. METHODOLOGY

A. Principle of sampling moiré method This sampling moiré method is an efficient phase analysis technique that performs analysis of phase distribution on single shot image. In this method, the fundamental principle is illustrated in Figure 1, fringes are gained by “down sampling” from sequential pixels followed by “intensity interpolation” digitally. By phase shifting spatially, i.e., changing start-sampling pixel point in succession such that the sampling interval is similar to the pitch of the specimen grating, series of moiré patterns can be attained. Eventually, from the series of phase shifted moiré patterns, the phase of moiré fringe is analyzed by using the phase shifting method [5] [6] [9] [10] [11].

In Figure 1(h–k), the k-th phase-shifted images can be shown approximately as follows:

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