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2018 Vol.34, Issue 2 Preview Page
Evaluation of Unit Weight and Strength of Sand Using Electro-mechanical Impedance

전기-역학적 임피던스를 이용한 모래의 단위중량 및 강도 평가

Sung-Sik Park1*
,
Seung-Wook Woo2
,
Jung-Shin Lee3
,
Sae-Byeok Lee3
,
Jun Cheol Lee4
박 성식1*
,
우 승욱2
,
이 정신3
,
이 새벽3
,
이 준철4
1Associate Prof., Dept. of Civil Eng., Kyungpook National Univ.
2Graduate Student, Dept. of Civil Eng., Kyungpook National Univ.
3Graduate Student, Dept. of Civil Eng., Kyungpook National Univ.
4Research Prof. DGRIT Development Center, Kyungpook National Univ.
1경북대학교 공과대학 건설환경에너지공학부 부교수
2경북대학교 공과대학 건설환경에너지공학부 석사과정
3경북대학교 공과대학 건설환경에너지공학부 박사과정
4 경북대학교 대경권국토교통기술지역거점센터 연구교수
*교신저자. *Corresponding Author. 
28 February 2018. pp. 33-42
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Abstract

In this study, the EMI (electro-mechanical impedance) of a small piezoelectric sensor was applied for measuring a unit weight and cementation (strength) of sand. Three different sizes of uncemented Nakdong River sand were filled loosely or densely into a compaction mold. A piezoelectric sensor with 20 mm in diameter was installed within sand for impedance measurement. A small Nakdong River sand was mixed with cement ratios of 4, 8 12, 16% and then compacted into a specimen with 50 mm in diameter and 100 mm in height. The specimen consisted of 6 layers with a sensor at the third layer. The impedance signals for 3 days and unconfined compressive strength at the 3rd day were measured. As the unit weight of uncemented sand increased, the resonant frequency increased slightly from 102 to 105 kHz but a conductance at resonant frequency decreased. For cemented sands, as the curing time and cement ratio increased, the resonant frequency increased significantly from 129 to 266 kHz but the conductance at resonant frequency decreased. The unconfined compressive strength (UCS) of cemented sands was between 289 and 1,390 kPa for different cement ratios. The relationship of UCS and resonant frequency linearly increased but one with a conductance at resonant frequency was in inverse proportion.

Keywords
Piezoelectric sensor
Electro-mechanical impedance
Resonant frequency
Conductance
Unconfined compressive strength
Cementation

본 연구에서는 소형 압전소자의 전기-역학적 임피던스를 이용하여 모래의 단위중량이나 강도를 평가하였다. 다짐 몰드 내 크기가 다른 세 종류의 미고결 낙동강모래를 느슨하거나 조밀하게 성형한 다음 내부에 직경 20mm 원형 모양의 납작한 압전소자를 설치하고 임피던스를 측정하였다. 또한, 가는 낙동강모래에 시멘트비 4, 8, 12, 16%로 직경 50mm, 높이 100mm의 고결 공시체를 6층으로 다져서 제작하였다. 고결 공시체의 3층 내부에 압전소자를 수평방향으 로 설치한 다음 3일 동안 임피던스 신호를 측정하였으며, 측정 후 일축압축시험을 실시하였다. 미고결 모래의 단위중 량이 증가함에 따라 공진주파수는 102kHz에서 105kHz까지 약간 증가하였으며, 공진주파수 발생 시 컨덕턴스는 감소 하였다. 고결 모래의 양생시간과 시멘트비가 증가함에 따라 공진주파수는 129kHz에서 266kHz까지 크게 증가하였으며, 공진주파수 발생 시 컨덕턴스는 반대로 감소하는 경향을 보였다. 고결 모래의 일축압축강도는 시멘트비에 따라 289-1,390kPa 정도이며, 공진주파수와는 뚜렷한 정비례 관계를 보이지만 공진주파수 발생 시 컨덕턴스와는 반비례 관계를 보였다.

References
1
Ayres, J. W., Lalande, F., Chaudhry, Z., and Rogers, C. A. (1998), “Qualitative Impedance-based Health Monitoring of Civil Infra-structures”, Smart Materials and Structures, Vol.7, No.5, pp.599- 605.
2
Chan, C. M. and Ch’ng, S. S. (2010), “Preliminary Study of S-wave Velocity and Unconfined Compressive Strength of Cement-PALF Stabilised Kaolin”, International Journal of Intergrated Engineering, Vol.2, No.2, pp.27-34.
3
Kim, Y. S., Jeong, W. S., and Kim, K. Y. (2006), “Shear behavior of River Sand due to Cement Contents”, Proceedings of the Korean Geotechnical Society fall national conference.
4
Lee, J. C., Shin, S. W., Kim, W. J., and Lee, C. J. (2016), “Electro- mechanical Impedance based Monitoring for the Setting of Cement Paste Using Piezoelectricity Sensor”, Smart Structures and Systems, Vol.17, No.1, pp.123-134.
5
Oh, S. H., Jung, J. W., Mok, Y. J., Park, D. S., and Park, C. S. (2008), “Correlation Undrained Shear Strength and Density of Silt with Shear Wave Velocity”, Journal of the Korean Geotechnical Society, Vol.24, No.5, pp.79-87.
6
Park, D. S. (2008), Relationship between shear modulus and undrained shear strength of normally consolidated silt, Ph.D. Thesis, Kyung Hee University.
7
Park, S. S. and Choi, S. K. (2011), “Effect of Fines on Unconfined Compressive Strength of Cemented Sands”, Journal of the Korean Society of Civil Engineers, Vol.31, No.6C, pp.213-220.
8
Park, G., Cudney, H. H., and Inman, D. J. (2000), “Impedance- based Health Monitoring of Civil Structural Components”, Journal of Infrastructure Systems, ASCE, Vol.6, No.4, pp.153-160.
9
Park, G., Cudney, H. H., and Inman, D. J. (2001), “Feasibility of Using Impedance-based Damage Assessment for Pipeline Structures”, Earthquake Engineering and Structural Dynamics, Vol.30, No.10, pp.1463-1474.
10
Park, S. S., Kim, K. Y., Choi, H. S., and Kim, C. W. (2009), “Effect of Different Curing Methods on the Unconfined Compressive Strength of Cemented Sand”, Journal of the Korean Society of Civil Engineers, Vol.29, No.5C, pp.207-215.
11
Park, S. S. and Lee, J. W. (2012), “Effect of Sea Water on Curing and Strength of Cemented Sand”, Journal of the Korean Geotechnical Society, Vol.28, No.6, pp.71-79.
12
Shirley, D. J. and Hampton, L. D. (1978), “Shear Wave Measure-ments in Laboratory Dediments”, J. Acoustical Society of America, Vol.63, No.2, pp.607-613.
13
Soh, C. K., Tseng, K. K. H., Bhalla, S., and Gupta, A. (2000), “Performance of Smart Piezoceramic Patches in Health Monitoring of a RC Bridge”, Smart Materials and Structures, Vol.9, No.4, pp.533-542.
14
Sun, F. P., Chaudhry, Z., Rogers, C. A., Majmundar, M., and Liang, C. (1995), “Automated Real-time Structure Health Monitoring via Signature Pattern Recognition”, SPIE Conference on Smart Structures and Materials, San Diego, California, Feb.27-Mar1, SPIE Vol.2443, pp.236-247.
15
Suwal, L. P. and Kuwano, R. (2013), “Disk Shaped Piezo-ceramic Transducer for P and S Wave Measurement in a Laboratory Soil Specimen”, Soils and Foundations, Vol.53, No.4, pp.510-524.
16
Thitimakorn, T., Kampananon, N., Jongjaiwanichkit, N., and Kupongsak, S. (2016), “Subsurface Void Detection under the Road Surface Using Ground Penetrating Radar (GPR), A Case Study in the Bangkok Metropolitan Area, Thailand” International Journal of Geo-Engineering, Volume 7, Paper no. 2, DOI 10.1186/s40703-016-0017-8.
Information
  • Publisher :The Korean Geotechnical Society
  • Publisher(Ko) :한국지반공학회
  • Journal Title :Journal of the Korean Geotechnical Society
  • Journal Title(Ko) :한국지반공학회 논문집
  • Volume : 34
  • No :2
  • Pages :33-42
  • Received Date : 2017-11-14
  • Revised Date : 2018-01-04
  • Accepted Date : 2018-01-31
  • DOI :https://doi.org/10.7843/kgs.2018.34.2.33
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