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Journal of the Korea Concrete Institute

J Korea Inst. Struct. Maint. Insp.
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  • Korea Citation Index (KCI)




์—ผํ•ด, ๋‚ด๊ตฌ์ˆ˜๋ช…, ํ™•์‚ฐ๊ณ„์ˆ˜, ํ‘œ๋ฉด์—ผํ™”๋ฌผ, ํ”ผ๋ณต๋‘๊ป˜
Chloride attack, Service life, Diffusion coefficient, Surface chloride content, Cover depth

1. ์„œ ๋ก 

์ฝ˜ํฌ๋ฆฌํŠธ๋‚ด๋ถ€๋กœ ์œ ์ž…๋œ ์—ผํ™”๋ฌผ ์ด์˜จ์€ ๋งค๋ฆฝ๋œ ๊ฐ•์žฌ์˜ ๋ถ€์‹ ์„ ์•ผ๊ธฐํ•˜๊ณ  ๋ถ€์‹๋Ÿ‰์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ผ ์‚ฌ์šฉ์„ฑ ๋ฐ ์•ˆ์ „์„ฑ ๋ฌธ์ œ๊ฐ€ ์ฆ๊ฐ€ํ•˜๊ฒŒ ๋œ๋‹ค(Broomfield, 1997). ๋งค๋ฆฝ๋œ ์ฒ ๊ทผ์— ๋ฐœ์ƒํ•˜๋Š” ๋ถ€์‹์€ ์ดˆ๊ธฐ์—๋Š” ๋ถ€์‹๋Ÿ‰์˜ ํŒฝ์ฐฝํšจ๊ณผ์— ๋”ฐ๋ผ ์—ญํ•™์  ์„ฑ๋Šฅ์ด ์ผ๋ถ€ ๊ฐœ์„ ๋˜๊ธฐ๋„ ํ•˜์ง€๋งŒ ๋ถ€์‹๋Ÿ‰์ด ๋ณดํ†ต 5.0% ์ด์ƒ ์ฆ๊ฐ€ํ•˜๊ฒŒ ๋˜๋ฉด ์Šฌ๋ฆฝํšจ๊ณผ๊ฐ€ ํฌ๊ฒŒ ์ง„์ „๋˜์–ด RC(Reinforced Concrete)์˜ ๊ธฐ๋ณธ๊ฐ€์ •์ธ ์ผ์ฒด์„ฑ์ด ์—†์–ด์ง€๊ฒŒ ๋œ๋‹ค(Chung et al., 2008; Hakan et al., 2012).

๊ธฐ์กด์˜ ๋งŽ์€ ์—ฐ๊ตฌ์—์„œ ์—ผํ•ด์— ๋…ธ์ถœ๋œ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๋‚ด๊ตฌ์ˆ˜๋ช… ์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๊ฐ€ ์ง„ํ–‰๋˜์—ˆ๋Š”๋ฐ, ํฌ๊ฒŒ ๊ฒฐ์ •๋ก ์ ์ธ ๋ฐฉ๋ฒ•๊ณผ ํ™•๋ฅ  ๋ก ์ ์ธ ๋ฐฉ๋ฒ•์œผ๋กœ ๋ถ„๋ฅ˜ํ•  ์ˆ˜ ์žˆ๋‹ค. ๊ฒฐ์ •๋ก ์ ์ธ ๋ฐฉ๋ฒ•์€ ์ฃผ๋กœ Fick's 2nd Law๋ฅผ ๊ธฐ๋ณธ์œผ๋กœ ํ•˜๋Š”๋ฐ, ์—ผํ™”๋ฌผ ์ด๋™์„ ์ง์ ‘์ ์œผ ๋กœ ํ‰๊ฐ€ํ•˜๋Š” ๋ฐฉ๋ฒ•์œผ๋กœ ์ฝ˜ํฌ๋ฆฌํŠธ ํ”ผ๋ณต๋‘๊ป˜, ์—ผํ™”๋ฌผ ํ™•์‚ฐ๊ณ„์ˆ˜, ๊ทธ๋ฆฌ๊ณ  ๋ถ€์‹์„ ์•ผ๊ธฐํ•˜๋Š” ์ž„๊ณ„์—ผํ™”๋ฌผ๋Ÿ‰์„ ์ฃผ์š” ๋ณ€์ˆ˜๋กœ ํ•˜๊ณ  ์žˆ๋‹ค. Fick's 2nd Law๋Š” ์ •์ƒ์ƒํƒœ๋ฅผ ๊ฐ€์ •ํ•˜๊ณ  ์žˆ์œผ๋ฏ€๋กœ ๊ฐ ๋ณ€ ์ˆ˜๋Š” ์‹œ๊ฐ„์— ๋”ฐ๋ผ ์ผ์ •ํ•œ ๊ฐ’์„ ๊ฐ€์ง€๋Š” ์ •์ƒ์ƒํƒœ(Steady-Sate Condition)์„ ๊ธฐ๋ณธ ๊ฐ€์ •์œผ๋กœ ํ•œ๋‹ค(Thomas and Bentz, 2002; CEB, 1997; RILEM, 1994). ์ตœ๊ทผ ๋“ค์–ด ์ดˆ๊ธฐ์žฌ๋ น ๊ฑฐ๋™์ธ ์ฝ˜ํฌ ๋ฆฌํŠธ์˜ ์ˆ˜ํ™”๋„ ๋ฐ ์ˆ˜๋ถ„์ด๋™์„ ๊ณ ๋ คํ•œ ์—ด์—ญํ•™์  ์—ฐ์„ฑํ•ด์„์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๋„ ๋งŽ์ด ์ง„ํ–‰๋˜๊ณ  ์žˆ๋Š”๋ฐ, ์ด๋Ÿฌํ•œ ํ•ด์„์€ ์ฃผ๋กœ Nernst- Einstein Equation์„ ์ง€๋ฐฐ๋ฐฉ์ •์‹์œผ๋กœ ์‚ฌ์šฉํ•˜๊ณ  ์žˆ๋‹ค. ์ด๋Ÿฌํ•œ ์‹์€ ์—ผํ™”๋ฌผ ์ด์˜จ์˜ ์œ ์ž…, ํ™•์‚ฐ ๋ฐ ์ˆ˜์••์— ์˜ํ•œ ์—ผํ™”๋ฌผ ์ด๋™ (Flux), ๊ทธ๋ฆฌ๊ณ  ์ˆ˜ํ™”๋ฌผ๊ณผ์˜ ํก์ฐฉ์„ ๊ณ ๋ คํ•˜์—ฌ ์—ผํ™”๋ฌผ ๊ฑฐ๋™์„ ํ•ด ์„ํ•œ๋‹ค(Maekawa et al., 2003; Song et al., 2006). ์‹ค๋ฌด์—์„œ ์‚ฌ ์šฉํ•˜๊ธฐ์—๋Š” ํ•ด์„ ๋ฐ ๊ฒฝ๊ณ„์กฐ๊ฑด์˜ ์–ด๋ ค์›€๊ณผ ์žฅ๊ธฐ ํ•ด์„์‹œ ์ˆ˜๋ ด ๋ฌธ์ œ๋กœ ์ธํ•ด ์ ๊ทน์ ์œผ๋กœ ํ™œ์šฉ๋˜์ง€ ๋ชปํ•˜๊ณ  ์žˆ๋‹ค. ์ด๋Ÿฌํ•œ ์—ฐ์„ฑ ํ•ด์„์—๋Š” ์ž์œ ์—ผํ™”๋ฌผ๊ณผ ๊ณ ์ •์—ผํ™”๋ฌผ์˜ ์ƒํ‰ํ˜•(Isotherm), ์—ผ ํ™”๋ฌผ์˜ ํ™•์‚ฐ์ด๋™๊ณผ ์••๋ ฅ์— ์˜ํ•œ ์ด๋™(Flux), ๊ทธ๋ฆฌ๊ณ  ์‹œ๋ฉ˜ํŠธ์ˆ˜ ํ™”๋ฌผ์— ์˜ํ•˜์—ฌ ํก์ฐฉ๋˜๋Š” ๊ณ ์ •์—ผํ™”๋ฌผ์„ ๊ฐ๊ฐ ๊ณ ๋ คํ•ด์•ผ ํ•˜๋Š” ์–ด๋ ค์›€์ด ์žˆ๋‹ค.

์ฝ˜ํฌ๋ฆฌํŠธ๋Š” ์‹œ๋ฉ˜ํŠธ๋ฅผ ๊ธฐ๋ณธ์œผ๋กœ ํ•˜๋Š” ๋ณตํ•ฉ์žฌ๋ฃŒ์ด๋ฏ€๋กœ ์žฌ๋ฃŒ ์ž์ฒด์˜ ๋ถˆํ™•์‹ค์„ฑ(Uncertainties)์ด ๋งค์šฐ ํฌ๋ฉฐ, ์‹œ๊ณต์‹œ์˜ ์ •๋„ ์— ๋”ฐ๋ผ ํ”ผ๋ณต๋‘๊ป˜์˜ ์˜ค์ฐจ๊ฐ€ ๋ฐœ์ƒํ•œ๋‹ค. ๋˜ํ•œ ์ž„๊ณ„์—ผํ™”๋ฌผ๋กœ ๊ทœ ์ •ํ•œ ๊ฐ’๋“ค(Hussain et al., 1995; Alonso et al., 2002) ์—ญ์‹œ ์—ฐ๊ตฌ ์ž ๋ฐ ๋…ธ์ถœํ™˜๊ฒฝ์— ๋”ฐ๋ผ ๋ณ€๋™ํ•˜๊ฒŒ ๋œ๋‹ค. ์ด๋Ÿฌํ•œ ๋ณ€๋™์„ฑ์„ ๊ฐ€์ง„ ์˜ํ–ฅ์ธ์ž์˜ ๋ณ€๋™์„ฑ์„ ๊ณ ๋ คํ•˜๊ธฐ ์œ„ํ•ด 1990๋…„๋Œ€๋ถ€ํ„ฐ ํ™•๋ฅ ๋ก ์  ์ธ ๋ฐฉ๋ฒ•์ด ๋„์ž…๋˜๊ธฐ ์‹œ์ž‘ํ–ˆ๋‹ค. ํ™•๋ฅ ๋ก ์  ๋ฐฉ๋ฒ•์€ Fick's 2nd Law ์™€ ๊ฐ™์€ ์—ผํ™”๋ฌผ ํ™•์‚ฐ๋ฐฉ์ •์‹์„ ์‚ฌ์šฉํ•˜์ง€๋งŒ, ๋ชฉํ‘œ ๋‚ด๊ตฌ์  ํŒŒ๊ดด ํ™•๋ฅ ๊ณผ ๋ถ€์‹์ด ๋ฐœ์ƒํ•  ํ™•๋ฅ ์„ ๋น„๊ตํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๊ฒฐ์ •๋ก ์ ์ธ ๋ฐฉ๋ฒ•์— ๋น„ํ•ด ๋ณด์ˆ˜์ ์œผ๋กœ ์•Œ๋ ค์ ธ ์žˆ๋‹ค(Kwon et al., 2009; Song et al., 2006).

์ตœ๊ทผ ๋“ค์–ด ํ”Œ๋ผ์ด์• ์‰ฌ(FA: Fly Ash)๋‚˜ ๊ณ ๋กœ ์Šฌ๋ž˜๊ทธ๋ฏธ๋ถ„๋ง (GGBFS: Ground Granulated Blast Furnace Slag)์™€ ๊ฐ™์€ ํ˜ผํ™” ์žฌ๊ฐ€ ์ ๊ทน์ ์œผ๋กœ ์‚ฌ์šฉ๋˜๋ฉด์„œ, ์‹œ๊ฐ„์— ๋”ฐ๋ฅธ ์—ผํ™”๋ฌผ ํ™•์‚ฐ๊ณ„์ˆ˜ ์˜ ๊ฐ์†Œ์— ๋Œ€ํ•œ ๊ด€์‹ฌ์ด ์ฆ๊ฐ€ํ•˜๊ณ  ์žˆ๋‹ค. Life365์™€ ๊ฐ™์€ ๊ฒฐ์ •๋ก  ์  ๋ฐฉ๋ฒ•์—์„œ๋„ ํ˜ผํ™”์žฌ์— ๋”ฐ๋ฅธ ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ์„ฑ์„ ๊ณ ๋ คํ•˜๊ณ  ์žˆ๋Š”๋ฐ, ํ˜ผํ™”์žฌ ์ˆ˜ํ™”์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ฅธ ๊ณต๊ทน๋ฅ  ๊ฐ์†Œ, ์™ธ๋ถ€ ๋ฐ ๋‚ด ๋ถ€ ๋†๋„์ฐจ์˜ ๊ฐ์†Œ์— ๋”ฐ๋ฅธ ํ™•์‚ฐ ์ €๊ฐ์„ฑ, ์ˆ˜ํ™”๋ฌผ ์ƒ์„ฑ์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ฅธ ์—ผํ™”๋ฌผ ํก์ฐฉ ์ฆ๊ฐ€ ๋“ฑ์— ๋”ฐ๋ผ ์—ผํ™”๋ฌผ ์ด๋™์ด ์ €ํ•ด๋˜๋Š” ๊ฑฐ ๋™์„ ๊ฐ„๋‹จํžˆ ์‹œ๊ฐ„์˜ ํ•จ์ˆ˜๋กœ ๊ตฌํ˜„ํ•œ ๊ฒƒ์ด๋‹ค(Lee and Kwon, 2012; Poulsen, 1993; Tang and Joost, 2007). ๊ฒฐ์ •๋ก ์ ์ธ ๋ฐฉ๋ฒ• ์— ๋Œ€ํ•ด์„œ๋Š” ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ๊ณ„์ˆ˜์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๋Š” ๊พธ์ค€ํžˆ ์ง„ ํ–‰๋˜์–ด ์™”๋Š”๋ฐ, ํ™•๋ฅ ๋ก ์ ์ธ ํ•ด์„์— ๋Œ€ํ•ด์„œ๋Š” ํ•ด์„์˜ ์–ด๋ ค์›€ ์œผ๋กœ ์ธํ•ด ์‹œ๊ฐ„ ์˜ํ–ฅ์„ ๊ณ ๋ คํ•œ ๋‚ด๊ตฌ์„ฑ ํ•ด์„์€ ๋งค์šฐ ์ œํ•œ์ ์œผ ๋กœ ์ˆ˜ํ–‰๋˜๊ณ  ์žˆ๋‹ค.

์—ผํ™”๋ฌผ ์œ ์ž…์„ ํšจ๊ณผ์ ์œผ๋กœ ์ œ์–ดํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ํ”ผ๋ณต๋‘๊ป˜๋ฅผ ์ฆ๊ฐ€์‹œํ‚ค๋Š” ๊ฒƒ์ด ๊ฐ€์žฅ ํšจ๊ณผ์ ์œผ๋กœ ์•Œ๋ ค์ ธ ์žˆ์œผ๋ฉฐ, ์ด๋Š” ์™ธ๋ถ€ ์—ผํ™”๋ฌผ๋Ÿ‰์˜ ๋ณ€ํ™”์— ๋ฏผ๊ฐํ•˜๊ฒŒ ๋ฐ˜์‘ํ•˜์—ฌ ๋‚ด๊ตฌ์ˆ˜๋ช… ์˜ํ–ฅ์„ ์ค€ ๋‹ค. ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์‹œ๊ฐ„์˜์กด์„ฑ์— ๋Œ€ํ•œ ํ™•์‚ฐ๊ณ„์ˆ˜์˜ ๋ณ€ํ™”๋ฅผ ๊ณ  ๋ คํ•˜์—ฌ ๊ฒฐ์ •๋ก ์ ์ธ ๋ฐฉ๋ฒ•๊ณผ ํ™•๋ฅ ๋ก ์ ์ธ ๋ฐฉ๋ฒ•์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์ˆ˜๋ช… ๋ณ€ํ™”๋ฅผ ๋ถ„์„ํ•˜๋„๋ก ํ•œ๋‹ค. ๋˜ํ•œ ์ฃผ์š” ์„ค๊ณ„๋ณ€์ˆ˜์ธ ํ”ผ๋ณต๋‘๊ป˜์™€ ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰์˜ ๋ณ€ํ™”๊ฐ€ ๋‚ด๊ตฌ์ˆ˜๋ช…์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ์ •๋Ÿ‰์ ์œผ ๋กœ ๋ถ„์„ํ•˜์˜€๋‹ค.

2. ๋‚ด๊ตฌ์ˆ˜๋ช… ํ‰๊ฐ€๋ฅผ ์œ„ํ•œ ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ๊ณ„์ˆ˜์˜ ์ ์šฉ ๋ชจ๋ธ๋ง

2.1. Fick's 2nd Law์— ๊ทผ๊ฑฐํ•œ ๊ฒฐ์ •๋ก ์  ๋ฐฉ๋ฒ•

๊ฒฐ์ •๋ก ์ ์ธ ๋ฐฉ๋ฒ•์€ ์‹ (1)๊ณผ ๊ฐ™์€ ์ง€๋ฐฐ๋ฐฉ์ •์‹์„ ์‚ฌ์šฉํ•˜์˜€ ๋‹ค. ํ‘œ๋ฉด์˜ ์—ผํ™”๋ฌผ๋Ÿ‰์€ ์ผ์ •ํ•˜๋‹ค๊ณ  ๊ฐ€์ •ํ•˜๋Š” Fickโ€™s 2nd Law ์—์„œ๋Š” ์—ผํ™”๋ฌผ๋Ÿ‰์„ ์ง์ ‘์ ์œผ๋กœ ์‚ฌ์šฉ์ž์—๊ฒŒ ์ œ๊ณตํ•˜๋ฏ€๋กœ ์ ์šฉ ํ•˜๊ธฐ ์‰ฌ์šด ์žฅ์ ์ด ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ๊ฒ‰๋ณด๊ธฐ ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ํ†ตํ•˜์—ฌ ๋„ ์ถœ๋˜๋ฏ€๋กœ ์žฅ๊ธฐ์‹คํ—˜ ๋˜๋Š” ์‹คํƒœ์กฐ์‚ฌ๊ฒฐ๊ณผ์— ์˜์กดํ•˜๋Š” ๋ฌธ์ œ์ ์ด ์žˆ๊ธฐ๋„ ํ•˜๋‹ค(CEB, 1997; RILEM, 1994).

(1)
C ( x , t ) = C s [ 1 โˆ’ e r f ( x 2 D ยฏ t ) ] , D ยฏ = D 28 ( t 28 t ) m

์—ฌ๊ธฐ์„œ, Cs๋Š” ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰, x ๋ฐ t๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ๊นŠ์ด ๋ฐ ์‹œ ๊ฐ„, erf๋Š” ์˜ค์ฐจํ•จ์ˆ˜๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. D๋Š” ์‹œ๊ฐ„์˜์กด์  ํ™•์‚ฐ๊ณ„์ˆ˜์ด ๋ฉฐ, ์žฌ๋ น 28์ผ ํ™•์‚ฐ๊ณ„์ˆ˜(D28)๊ณผ ๊ธฐ์ค€ ์‹œ๊ฐ„(t28)์„ ํฌํ•จํ•˜๊ณ  ์žˆ ๋‹ค. m์€ ์‹œ๊ฐ„์ง€์ˆ˜์ธ๋ฐ, ํ˜ผํ™”์žฌ์˜ ์‚ฌ์šฉ์— ๋”ฐ๋ผ 0.2~0.6์‚ฌ์ด์˜ ๊ฐ’์„ ๊ฐ€์ •ํ•˜์—ฌ ์‹œ๊ฐ„์— ๋”ฐ๋ฅธ ์—ผํ™”๋ฌผ ๊ฐ์†Œ๋ฅผ ์ˆ˜์น˜์ ์œผ๋กœ ๊ตฌํ˜„ ํ•˜๊ณ  ์žˆ๋‹ค(Thomas and Bentz, 2002).

๊ฒฐ์ •๋ก ์ ์ธ ๋ฐฉ๋ฒ•์—์„œ๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ๋กœ ์œ ์ž…๋œ ์—ผํ™”๋ฌผ๋Ÿ‰์ด ์ตœ ์™ธ๊ฐ ์ฒ ๊ทผ ์œ„์น˜์—์„œ ๋ชฉํ‘œ๋‚ด๊ตฌ์ˆ˜๋ช… ๋™์•ˆ ์ž„๊ณ„์—ผํ™”๋ฌผ๋Ÿ‰์„ ์ดˆ๊ณผ ํ•˜์ง€ ์•Š๋Š” ์ƒํƒœ๋ฅผ ํ•œ๊ณ„์ƒํƒœ๋กœ ์ •ํ•˜๊ณ  ์žˆ๋‹ค(JSCE, 2002, 2007; KCI, 2012).

2.2. MCS์— ๊ทผ๊ฑฐํ•œ ํ™•๋ฅ ๋ก ์  ๋ฐฉ๋ฒ•

ํ™•๋ฅ ๋ก ์ ์ธ๋ฐฉ๋ฒ•์€์ฃผ๋กœ MCS(Monte Carlo Simulation)์„ ์ด์šฉํ•˜์—ฌ ํ™•๋ฅ ๋ณ€์ˆ˜๋“ค์— ๋Œ€ํ•œ ๋ณ€๋™์„ฑ์„ ๊ณ ๋ คํ•œ๋‹ค. Fig. 1์—์„œ ๋Š” ํ™•๋ฅ ๋ก ์ ์ธ ์„ค๊ณ„๋ฐฉ๋ฒ•์˜ ๊ฐœ์š”๋„๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋Š”๋ฐ, ์—ดํ™”์™ธ๋ ฅ (St)๋Š” ์‹œ๊ฐ„์— ๋”ฐ๋ผ ์ฆ๊ฐ€ํ•˜๋Š” ์œ ์ž…๋œ ์—ผํ™”๋ฌผ๋Ÿ‰์œผ๋กœ ํ•˜์˜€์œผ๋ฉฐ, ์ €ํ•ญ๋‚ด๋ ฅ(Rt)๋Š” ๋ถ€์‹๋ฐœ์ƒ์˜ ์ž„๊ณ„์—ผํ™”๋ฌผ๋Ÿ‰์œผ๋กœ ํ•˜๋Š” ๊ฒƒ์ด ์ผ ๋ฐ˜์ ์ด๋‹ค(Ferreira et al., 2004; DuraCrete Final Report, 2000). ์‹ (2)์—์„œ๋Š” ๋ณธ ์—ฐ๊ตฌ์—์„œ ์ ์šฉ๋˜๋Š” ํ™•๋ฅ ๋ก ์  ์„ค๊ณ„์˜ ์ง€๋ฐฐ๋ฐฉ ์ •์‹์„ ๋‚˜ํƒ€๋‚ธ๋‹ค.

Fig. 1

Probabilistic method for durability design

JKSMI-20-65_F1.jpg

(2)
P { C c r ( ฮผ , ฯƒ ) < C s ( ฮผ , ฯƒ ) [ 1 โˆ’ e r f ( x ( ฮผ , ฯƒ ) D ( ฮผ , ฯƒ ) t ) ] } < P max

์—ฌ๊ธฐ์„œ, Ccr (ฮผ, ฯƒ) ๋Š” ์ž„๊ณ„๋ถ€์‹๋Ÿ‰์˜ ํ™•๋ฅ ๋ณ€์ˆ˜์ด๋ฉฐ, Pmax ๋Š” ๋ชฉํ‘œ๋‚ด๊ตฌ์ˆ˜๋ช…๋™์•ˆ ์œ ์ง€๋˜์–ด์•ผ ํ•˜๋Š” ์˜ˆ์ƒ๋˜๋Š” ๋ชฉํ‘œ ๋‚ด๊ตฌ์„ฑ ํŒŒ ๊ดดํ™•๋ฅ ์˜ ์ตœ๋Œ€์น˜์ด๋‹ค. ๊ฐ๊ตญ์—์„œ๋Š” 7.0~10.0% ์ˆ˜์ค€์˜ ๋ชฉํ‘œ๋‚ด ๊ตฌ์„ฑ ํŒŒ๊ดดํ™•๋ฅ ์„ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š”๋ฐ(EN 1991, 2000; JSCE, 2007), ๊ตญ๋‚ด์—์„œ๋Š” ํƒ„์‚ฐํ™”์™€ ์—ผํ•ด์— ๋Œ€ํ•˜์—ฌ 10.0%์˜ ๋ชฉํ‘œ๋‚ด๊ตฌ์  ํŒŒ ๊ดดํ™•๋ฅ ์„ ์ •ํ•˜๊ณ  ์žˆ๋‹ค(KCI, 2012).

MCS์—์„œ ์‹œ๊ฐ„์˜์กด์„ฑ์„ ๊ณ ๋ คํ•˜๊ธฐ๋Š” ๋งค์šฐ ์–ด๋ ค์šด ๋ฌธ์ œ์ด ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์ผ์ •ํ•œ ์ •์ƒ์ƒํƒœ ์กฐ๊ฑด์—์„œ๋Š” ๋งค๊ฐœ๋ณ€์ˆ˜ I(t) ๋ฅผ ์ด ์šฉํ•˜์—ฌ ์‹ (3)๊ณผ ๊ฐ™์ด ์ผ์ •์‹œ๊ฐ„์—์„œ์˜ ๊ท ๋“ฑํ•œ ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ๋ชจ ๋ธ๋ง ํ•  ์ˆ˜ ์žˆ๋‹ค(Poulsen, 1993).

(3)
D ( t ) = โˆซ 0 t D ( ฯ„ ) d ( ฯ„ )

์‹ (3)์„ ๊ณ ๋ คํ•˜๋ฉด ์‹ (1)์—์„œ์˜ D๋Š” m์„ ์ƒ์ˆ˜๋กœ ๊ฐ€์ง€๋Š” D(m)์œผ๋กœ ๋‚˜ํƒ€๋‚ผ ์ˆ˜๊ฐ€ ์žˆ์œผ๋ฉฐ ์ด๋Š” ์‹ (4a, 4b)์™€ ๊ฐ™๋‹ค.

(4a)
D ( m ) = D 0 1 โˆ’ m ( t 0 t ) , โ€‰ ( t < t c )

(4b)
D ( m ) = D 0 1 โˆ’ m ( t 28 t c ) m [ 1 โˆ’ m + m t c t ] , โ€‰ ( t โ‰ฅ t c )

์—ฌ๊ธฐ์„œ, D(m)์€ ์‹œ๊ฐ„ t(sec)์—์„œ์˜ ํ™•์‚ฐ๊ณ„์ˆ˜(m2/sec), D0๋Š” t0์—์„œ์˜ ํ™•์‚ฐ๊ณ„์ˆ˜, tc๋Š” ํ™•์‚ฐ๊ณ„์ˆ˜๊ฐ€ ๋” ์ด์ƒ ๊ฐ์†Œํ•˜์ง€ ์•Š๋Š” ์‹œ๊ฐ„์„ ๋‚˜ํƒ€๋‚ด๋ฉฐ, ์ผ๋ฐ˜์ ์œผ๋กœ tc๋Š” 30๋…„์œผ๋กœ ๊ฐ€์ •ํ•˜๊ณ  ์žˆ๋‹ค (Thomas and Bamforth, 1999). ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ๊ณ ๋ ค ํ•œ ํ™•๋ฅ ๋ก ์  ๋ฐฉ๋ฒ•์˜ ํ•ด์„๋ฐฉ๋ฒ•์€ Fig. 2์™€ ๊ฐ™๋‹ค.

Fig. 2

Flowchart for calculation of durability failure probability

JKSMI-20-65_F2.jpg

3. ๋ณ€์ˆ˜๋ณ„ ์‹œ๋ฎฌ๋ ˆ์ด์…˜์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์  ํŒŒ๊ดดํ™•๋ฅ ์˜ ๋ณ€ํ™”

3.1. ์‹œ๋ฎฌ๋ ˆ์ด์…˜ ๊ธฐ๋ณธ ์กฐ๊ฑด

๋ณธ ์ ˆ์—์„œ๋Š” ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ์„ฑ์„ ๊ฐ€์ง„ ๋‚ด๊ตฌ์„ฑ ์„ค๊ณ„๋ฐฉ๋ฒ• (๊ฒฐ์ •๋ก ์  ๋ฐฉ๋ฒ• ๋ฐ ํ™•๋ฅ ๋ก ์  ๋ฐฉ๋ฒ•)๊ณผ ์™ธ๋ถ€์กฐ๊ฑด(ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰ ๋ฐ ํ”ผ๋ณต๋‘๊ป˜)์ด ๋‚ด๊ตฌ์ˆ˜๋ช…์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ๋ถ„์„ํ•˜๊ธฐ ์œ„ํ•ด, ๋Œ€ ์ƒ ๊ตฌ์กฐ๋ฌผ์„ Table 1๊ณผ ๊ฐ™์ด ์„ค์ •ํ•˜์˜€๋‹ค. ํ•ด์„์„ ์œ„ํ•œ ๊ธฐ๋ณธ์กฐ ๊ฑด์€ Table 1์—์„œ bold๋กœ ํ‘œ์‹œ๋œ ์ƒ์ˆ˜๋ฅผ ๊ธฐ๋ณธ์œผ๋กœ ํ•˜์˜€์œผ๋ฉฐ, ๊ธฐ์กด์˜ ์—ฐ๊ตฌ๋ฅผ ์ฐธ๊ณ ํ•˜์—ฌ ๊ฐ ์ธ์ž์˜ ํ™•๋ฅ ํŠน์„ฑ ๋ฐ ๋ณ€๋™๊ณ„์ˆ˜๋ฅผ ๊ฐ€์ •ํ•˜์˜€๋‹ค(Song et al., 2009). ์ฐธ๊ณ ๋กœ ๊ธฐ๋ณธํ™•์‚ฐ๊ณ„์ˆ˜(Dref)๋Š” 2.5~7.5ร—10-12m2/sec๋กœ ๊ฐ€์ •ํ•˜์—ฌ ๋‚ด๊ตฌ์ˆ˜๋ช…์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ๊ฐ™์ด ๋ถ„์„ํ•˜์˜€๋‹ค.

Table 1

Simulation conditions with variables

Time constant and time-dependent diffusion coefficient

Diffusion coefficient at reference time (28days) 2.5ร—10-12m2/sec Normal
5.0ร—10-12m2/sec distribution
7.5ร—10-12m2/sec COV 0.266

Cover depth 75 mm Normal
100 mm distribution
125 mm COV 0.128

Surface chloride content 5.0 kg/m3 Normal
10.0 kg/m3 distribution
15.0 kg/m3 COV 0.338

3.2. ๊ธฐ๋ณธํ™•์‚ฐ๊ณ„์ˆ˜ ์˜ํ–ฅ์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์„ฑํŒŒ๊ดดํ™•๋ฅ ์˜ ๋ณ€ํ™”

์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ์„ฑ๊ณผ ๊ธฐ๋ณธํ™•์‚ฐ๊ณ„์ˆ˜์˜ ๋ณ€ํ™”๊ฐ€ ๋‚ด๊ตฌ์  ํŒŒ๊ดด ํ™•๋ฅ ์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ๊ณ ๋ คํ•˜๊ธฐ ์œ„ํ•˜์—ฌ Table 1์˜ ์กฐ๊ฑด๊ณผ ๊ฐ™ ์ด ๊ธฐ๋ณธํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ 5.0ร—10-12m2/sec์—์„œ 10.0ร—10-12m2/sec๊นŒ ์ง€ 2๋ฐฐ๋กœ ์ฆ๊ฐ€์‹œํ‚ค๋ฉด์„œ ํ•ด์„์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. Fig. 3์—์„œ๋Š” ๊ธฐ๋ณธ ํ™•์‚ฐ๊ณ„์ˆ˜ ๋ณ€ํ™”์— ๋”ฐ๋ฅธ PDF(Probability of Durability Failure)๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ํ™•์‚ฐ๊ณ„์ˆ˜์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ผ PDF์˜ ๋ณ€ํ™”๊ฐ€ ๋น ๋ฅด๊ฒŒ ์ฆ๊ฐ€ํ•˜๊ณ  ์žˆ์Œ์„ ์•Œ ์ˆ˜ ์žˆ์œผ๋ฉฐ, PDF์˜ ๋ณ€ํ™”๋ฅผ ์ •๋Ÿ‰์ ์œผ๋กœ ํ‰ ๊ฐ€ํ•˜๊ธฐ ์œ„ํ•ด, 100๋…„๊ฐ„์˜ PDF๋ฅผ ํ‰๊ท ํ•˜์—ฌ ํ™•์‚ฐ๊ณ„์ˆ˜์˜ ๋ณ€ํ™”์™€ ๋น„๊ต๋ฅผ Fig. 3(d)์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

Fig. 3

Variation changes in PDF with diffusion coefficient at reference time

JKSMI-20-65_F3.jpg

Fig. 3์—์„œ ์•Œ ์ˆ˜ ์žˆ๋“ฏ์ด ํ™•์‚ฐ๊ณ„์ˆ˜๊ฐ€ 7.5ร—10-12m2/sec๋กœ ์ฆ ๊ฐ€ํ•  ๊ฒฝ์šฐ, ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ PDF๋Š” 21.5% ์—์„œ 62.6%๋กœ ์ฆ๊ฐ€ํ•˜์˜€์œผ๋ฉฐ, ๊ณ ์ •๋œ ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ ์˜ PDF๋Š” 64.2%์—์„œ 84.5%๋กœ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ๊ณ ์ • ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ๋ณด๋‹ค ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ์‚ฌ์šฉํ•œ ๊ฒฝ์šฐ, PDF ์˜ ์ฆ๊ฐ€๊ฐ€ ๋”์šฑ ๋šœ๋ ทํ•˜๋‹ค. ์ด๋Š” ๊ณ ์ •๋œ ํ™•์‚ฐ๊ณ„์ˆ˜๋Š” ๊ฐ์†Œํ•˜์ง€ ์•Š์œผ๋ฏ€๋กœ ์—ผํ™”๋ฌผ๋Ÿ‰์ด ๊ณ„์†์—์„œ ์ผ์ •ํ•˜๊ฒŒ ์œ ์ž…๋˜๊ณ  ์ด๋กœ ์ธํ•ด PDF๊ฐ€ ์ปค์ง์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. ์ฆ๊ฐ€์œจ์€ ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ์„ ์ด์šฉ ํ•œ ๊ฒฝ์šฐ์—์„œ๋„ ํฌ๊ฒŒ ์ฆ๊ฐ€ํ–ˆ๋Š”๋ฐ ์ด๋Š” PDF๊ฐ€ ์ดˆ๊ธฐ์—๋Š” ๋‚ฎ๊ณ  ๊ธฐ๊ฐ„์ด ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ๋น„์„ ํ˜•์ ์œผ๋กœ ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜๊ธฐ ๋•Œ๋ฌธ์ด ๋‹ค. ์ ˆ๋Œ€๋Ÿ‰์„ ๋น„๊ตํ•˜๋ฉด ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ์˜ ๊ฒฝ์šฐ, ๊ณ ์ • ํ™•์‚ฐ์˜ ๊ฒฝ์šฐ์— ๋น„ํ•˜์—ฌ 74.1% ์ˆ˜์ค€์œผ๋กœ ํ‰๊ฐ€๋˜์—ˆ๋‹ค.

3.3. ํ”ผ๋ณต๋‘๊ป˜์˜ ์˜ํ–ฅ์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์„ฑํŒŒ๊ดดํ™•๋ฅ ์˜ ๋ณ€ํ™”

์ฝ˜ํฌ๋ฆฌํŠธ ํ”ผ๋ณต๋‘๊ป˜๋Š” ๊ฐ€์žฅ ์ผ๋ฐ˜์ ์ด๋ฉฐ 1์ฐจ์ ์ธ ์ค‘์š” ๋ฐฉ์–ด ๊ธฐ์žฌ์ด๋‹ค. ๋ณธ ์ ˆ์—์„œ๋Š” 75 mm์—์„œ 125 mm๋กœ ํ”ผ๋ณต๋‘๊ป˜๋ฅผ ์ฆ ๊ฐ€์‹œํ‚ค๋ฉด์„œ PDF๋ฅผ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ๊ณ ๋ ค ํ•œ ๊ฒฝ์šฐ PDF์˜ ์ฆ๊ฐ€๋Š” ๋งค์šฐ ๋‚ฎ์€ ์ˆ˜์ค€์œผ๋กœ ํ‰๊ฐ€๋˜์—ˆ์œผ๋ฉฐ ์ด ๋Š” ๋‚ด๊ตฌ์ˆ˜๋ช…์˜ ์ฆ๊ฐ€๋กœ ์—ฐ๊ณ„๋œ๋‹ค. Fig. 4์—์„œ๋Š” ํ”ผ๋ณต๋‘๊ป˜์˜ ์ฆ ๊ฐ€์— ๋”ฐ๋ฅธ PDF๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ์œผ๋ฉฐ, Fig. 4(d)์—์„œ๋Š” ํ‰๊ท  PDF์˜ ๋ณ€ํ™”๋ฅผ ๋„์‹œํ•˜์˜€๋‹ค.

Fig. 4

Variation changes in PDF with cover depth

JKSMI-20-65_F4.jpg

Fig. 4์—์„œ ์•Œ ์ˆ˜ ์žˆ๋“ฏ์ด, ํ”ผ๋ณต๋‘๊ป˜์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ผ PDF๋Š” ๋น  ๋ฅด๊ฒŒ ๊ฐ์†Œํ•˜๊ณ  ์žˆ์œผ๋ฉฐ, ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ์‚ฌ์šฉํ–ˆ์„ ๊ฒฝ ์šฐ๋Š” 21.5%์—์„œ 0.57%๋กœ, ๊ณ ์ • ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ์‚ฌ์šฉํ–ˆ์„ ๊ฒฝ์šฐ๋Š” 64.2%์—์„œ 26.8%๋กœ ๊ฐ์†Œํ•˜์˜€๋‹ค. ํ”ผ๋ณต๋‘๊ป˜๊ฐ€ ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ PDF์˜ ๋ณ€ํ™”๊ฐ€ ํฌ๊ฒŒ ๋ณ€๋™ํ•˜๋ฏ€๋กœ ๋‚ด๊ตฌ์„ฑ ํ‰๊ฐ€์— ํ•ต์‹ฌ์ ์ธ ์ธ ์ž์ž„์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค.

3.4. ํ‘œ๋ฉด์—ผํ™”๋ฌผ์˜ ์˜ํ–ฅ์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์„ฑํŒŒ๊ดดํ™•๋ฅ ์˜ ๋ณ€ํ™”

๋ณธ ์ ˆ์—์„œ๋Š” ํ‘œ๋ฉด์—ผํ™”๋ฌผ์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ฅธ PDF์˜ ๋ณ€ํ™”๋ฅผ ์‹œ ๊ฐ„์˜์กด์„ฑ ๋ฐ ๊ณ ์ • ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ์ด์šฉํ•˜์—ฌ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ์ผ๋ฐ˜์  ์œผ๋กœ ํ‘œ๋ฉด์—ผํ™”๋ฌผ์€ ์‹œ๊ฐ„์— ๋”ฐ๋ผ์„œ ์ฆ๊ฐ€ํ•˜๊ณ  10๋…„ ์ •๋„ ํ›„์— ์ผ์ •ํ•˜๋‹ค๊ณ  ๋ณด๊ณ ๋˜๊ณ  ์žˆ์œผ๋‚˜(JSCE, 2002), ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ๊ฒฐ ์ •๋ก ์  ๋ฐฉ๋ฒ•๊ณผ ํ™•๋ฅ ๋ก ์  ๋ฐฉ๋ฒ•์„ ๋น„๊ตํ•˜๊ธฐ ์œ„ํ•ด ๊ณต์šฉ ๊ฐœ์‹œ ์ดˆ ๋ถ€ํ„ฐ ํ‘œ๋ฉด์—ผํ™”๋ฌผ์ด ์ผ์ •ํ•˜๋‹ค๊ณ  ๊ฐ€์ •ํ•˜์˜€๋‹ค.

Fig. 5์—์„œ๋Š” ํ‘œ๋ฉด์—ผํ™”๋ฌผ์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ฅธ PDF์˜ ๋ณ€ํ™”๋ฅผ ๋‚˜ ํƒ€๋‚ด์—ˆ์œผ๋ฉฐ, Fig. 5(d)์—์„œ๋Š” ํ‰๊ท  PDF์˜ ๋ณ€ํ™”๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

Fig. 5

Variation changes in PDF with surface chloride content

JKSMI-20-65_F5.jpg

Fig. 5์—์„œ ์•Œ ์ˆ˜ ์žˆ๋“ฏ์ด, ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ํ‰๊ท  PDF๋Š” ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜๋Š”๋ฐ, ์ด๋Š” ๊ฒฝ๊ณ„์กฐ๊ฑด์ด ํฐ ๊ฐ’์„ ๊ฐ€์ง€๋ฏ€๋กœ ๋‚ด๋ถ€๋กœ์˜ ์œ ์ž…์ด ์ฆ๊ฐ€ํ•˜๊ฒŒ ๋˜๋Š” ๊ฒƒ์ด๋‹ค. ์ผ๋ฐ˜์ ์œผ๋กœ ํ•ด์ˆ˜์— ์นจ์ง€๋œ ์žฅ๊ธฐ ์‹œํŽธ์˜ ๊ฒฝ์šฐ 18.0~23.0 kg/m3์˜ ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰์„ ๊ฐ€์ง€๊ณ  ์žˆ๋‹ค. 5 kg/m3์˜ ๊ฒฝ์šฐ๋Š” ๋น„๋ง๋Œ€ ์กฐ๊ฑด์„, 10 kg/m3์˜ ๊ฒฝ ์šฐ๋Š” ์กฐ์„๋Œ€ ๊ตฌ๊ฐ„์˜ ์—ผํ™”๋ฌผ๋Ÿ‰๊ณผ ๋น„์Šทํ•œ ์ˆ˜์ค€์ด๋‹ค(Broomfield, 1997). ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰์ด 5.0 kg/m3์—์„œ 15 kg/m3์œผ๋กœ ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ํ‰๊ท  PDF๋Š” ๊ณ ์ • ํ™•์‚ฐ๊ณ„์ˆ˜์ธ ๊ฒฝ์šฐ 64.2%์—์„œ 83.6%๋กœ, ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ๊ณ„์ˆ˜์ธ ๊ฒฝ์šฐ๋Š” 21.5%์—์„œ 57.7%๋กœ ์ฆ๊ฐ€ํ•˜ ์˜€๋‹ค. ์ฆ๊ฐ€์œจ์„ ํ‰๊ฐ€ํ•˜๋ฉด ๋‘ ๊ฐ€์ง€ ๊ฒฝ์šฐ ๋ชจ๋‘ ํ”ผ๋ณต๋‘๊ป˜์˜ ์˜ํ–ฅ ๊ณผ ๋น„์Šทํ•˜๊ฒŒ ํ‰๊ฐ€๋˜์—ˆ๋‹ค.

4. ์‹œ๋ฎฌ๋ ˆ์ด์…˜์„ ํ†ตํ•œ ๋‚ด๊ตฌ์ˆ˜๋ช…์— ๋Œ€ํ•œ ์‹œ๊ฐ„์˜์กด์„ฑ ์˜ํ–ฅ๋„ ๋ถ„์„

4.1. ๋‚ด๊ตฌ์ˆ˜๋ช… ๋„์ถœ ๊ฐœ์š”

๋ณธ ์žฅ์—์„œ๋Š” ๊ฒฐ์ •๋ก ์ ์ธ ๋ฐฉ๋ฒ•์„ ํ†ตํ•œ ๋‚ด๊ตฌ์ˆ˜๋ช…๊ณผ 3.1์ ˆ์— ์„œ ์„ค๋ช…ํ•œ ๋‚ด๊ตฌ์  ํŒŒ๊ดดํ™•๋ฅ ์„ ๊ณ ๋ คํ•œ ํ™•๋ฅ ๋ก  ํ‰๊ฐ€๋ฐฉ๋ฒ•๊ณผ์˜ ๋น„๊ต๋ฅผ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ๊ฒฐ์ •๋ก ์  ๋ฐฉ๋ฒ•์œผ๋กœ๋Š” ๋ฒ”์šฉ ํ”„๋กœ๊ทธ๋žจ์ธ Life 365๋ฅผ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ํ•ด์„์กฐ๊ฑด์€ Table 1์— ๋‚˜ํƒ€๋‚œ ํ‰๊ท ๊ฐ’ (๊ธฐ๋ณธ ํ™•์‚ฐ๊ณ„์ˆ˜, ํ”ผ๋ณต๋‘๊ป˜, ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰)์„ ๊ฐ ํ•ด์„ ๊ฒฝ์šฐ์— ์‚ฌ์šฉํ•˜์˜€๋‹ค. ๊ฒฐ์ •๋ก ์  ๋ฐฉ๋ฒ•์—์„œ๋Š” ์ž„๊ณ„ ์—ผํ™”๋ฌผ๋Ÿ‰์„ ์‹œ๋ฐฉ์„œ (JSCE, 2007; KCI, 2012)์—์„œ ์ œ์•ˆํ•˜๋Š” 1.2 kg/m3์„ ์‚ฌ์šฉํ•˜์˜€ ์œผ๋ฉฐ, ํ™•๋ฅ ๋ก ์  ๋ฐฉ๋ฒ•์—์„œ๋Š” ๋ชฉํ‘œ๋‚ด๊ตฌ์  ํŒŒ๊ดดํ™•๋ฅ ์„ 10.0%๋กœ ์„ค์ •ํ•˜์˜€๋‹ค(KCI, 2012). ์ผ๋ฐ˜์ ์œผ๋กœ ํ™•๋ฅ ๋ณ€์ˆ˜์˜ ๋ณ€๋™์„ฑ ์˜ํ–ฅ ๊ณผ ๋‚ฎ์€ ๋ชฉํ‘œ๋‚ด๊ตฌ์  ํŒŒ๊ดดํ™•๋ฅ ๋กœ ์ธํ•ด, ํ™•๋ฅ ๋ก ์  ๋ฐฉ๋ฒ•์„ ํ†ตํ•ด ๋„์ถœ๋œ ๋‚ด๊ตฌ์ˆ˜๋ช…์€ ๊ฒฐ์ •๋ก ์ ์ธ ๋ฐฉ๋ฒ•๋ณด๋‹ค ๋‚ฎ๊ฒŒ ํ‰๊ฐ€๋œ๋‹ค (Kwon et al., 2009).

4.2. ์˜ํ–ฅ์ธ์ž ๋ณ€ํ™”์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์ˆ˜๋ช… ๋ณ€ํ™” ๋ถ„์„

4.2.1. ํ•ด์„์กฐ๊ฑด ๋ฐ ํ‰๊ฐ€ ๊ฒฐ๊ณผ

๊ฐ ํ•ด์„์กฐ๊ฑด์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์ˆ˜๋ช… ๋ฐฉ๋ฒ•๊ณผ ๊ทธ ๊ฒฐ๊ณผ๋ฅผ Table 2์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ํ•ด์„์กฐ๊ฑด์€ ๊ฒฐ์ •๋ก ์  ๋ฐฉ๋ฒ•์—์„œ์˜ ์‹œ๊ฐ„์˜์กด์„ฑ ์œ  ๋ฌด, ๊ทธ๋ฆฌ๊ณ  ํ™•๋ฅ ๋ก ์  ๋ฐฉ๋ฒ•์—์„œ์˜ ์‹œ๊ฐ„์˜์กด์„ฑ ์œ ๋ฌด์— ๋”ฐ๋ผ ์ด 4 ๊ฐ€์ง€ ๊ฒฝ์šฐ์˜ ๋‚ด๊ตฌ์ˆ˜๋ช… ํ‰๊ฐ€๊ฒฐ๊ณผ๋ฅผ ์š”์•ฝํ•˜์˜€๋‹ค.

Table 2

Analysis conditions and service life evaluation

Common analysis conditions
  • Diffusion coefficient at reference time: 2.5ร—10-12m2/sec

  • Cover depth: 75 mm

  • Surface chloride content: 5.0 kg/m3

  • Critical chloride content: 1.2 kg/m3

  • Time exponent: 0.2


Variables Service life

Deterministic Probabilistic

Time constant Time-dep endent Time constant Time-dep endent

Diffusion coefficient at reference time (10-12m2/sec) 2.5 26.8 76.0 13.2 38.5
5.0 13.0 35.1 8.8 17.2
7.5 8.6 21.3 4.7 9.8

Cover depth (mm) 75 26.8 76.0 13.2 38.5
100 45.7 140.0 26.0 76.1
125 71.6 222.4 38.1 120.0

Surface chloride content (kg/m3) 5.0 26.8 76.0 13.2 38.5
10.0 14.7 40.8 8.8 21.2
15.0 12.7 31.1 7.2 17.5

4.2.1. ๊ธฐ๋ณธํ™•์‚ฐ๊ณ„์ˆ˜ ๋ณ€ํ™”์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์ˆ˜๋ช…

Table 2์— ๊ธฐ์ž…๋œ ๊ณตํ†ต์กฐ๊ฑด์— ๋Œ€ํ•ด์„œ ๊ธฐ๋ณธํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ๋ณ€ํ™” ์‹œํ‚ค๋ฉด์„œ 4๊ฐ€์ง€ ์กฐ๊ฑด์— ๋Œ€ํ•˜์—ฌ ๋‚ด๊ตฌ์ˆ˜๋ช…์„ ๋„์ถœํ•˜์˜€๋‹ค. Fig. 6 ์—์„œ๋Š” ๊ธฐ๋ณธํ™•์‚ฐ๊ณ„์ˆ˜์˜ ๋ณ€ํ™”์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์ˆ˜๋ช…์˜ ๋ณ€ํ™”๋ฅผ ๋‚˜ํƒ€ ๋‚ด๊ณ  ์žˆ๋‹ค.

Fig. 6

Service life with varying diffusion coefficient at reference time

JKSMI-20-65_F6.jpg

Fig. 6์—์„œ ์•Œ ์ˆ˜ ์žˆ๋“ฏ์ด ์‹œ๊ฐ„์˜์กด์„ฑ์ด ๊ณ ๋ ค๋œ ๊ฒฐ์ •๋ก ์  ๋ฐฉ ๋ฒ•์—์„œ ๊ฐ€์žฅ ํฐ ๋‚ด๊ตฌ์ˆ˜๋ช…์ด ์˜ˆ์ธก๋˜์—ˆ์œผ๋ฉฐ, ์‹œ๊ฐ„์˜์กด์„ฑ์ด ๊ณ  ๋ ค๋˜์ง€ ์•Š์€ ํ™•๋ฅ ๋ก ์  ํ•ด์„์—์„œ ๊ฐ€์žฅ ๋‚ฎ์€ ๋‚ด๊ตฌ์ˆ˜๋ช…์ด ํ‰๊ฐ€ ๋˜์—ˆ๋‹ค. ์‹œ๊ฐ„์˜์กด์„ฑ ํ•ด์„์€ ์ผ๋ฐ˜์ ์œผ๋กœ ๊ฒฐ์ •๋ก ์  ๋ฐฉ๋ฒ•์—๋งŒ ์ ์šฉ๋˜๋Š”๋ฐ, ํ™•๋ฅ ๋ก ์  ํ•ด์„์— ์ ์šฉํ•จ์œผ๋กœ์„œ ๋‘ ๋ฐฉ๋ฒ•์—์„œ ๋„ ์ถœ๋˜๋Š” ๋‚ด๊ตฌ์ˆ˜๋ช…์˜ ์ฐจ์ด๋ฅผ ๊ฐ์†Œ์‹œํ‚ฌ ์ˆ˜ ์žˆ๋‹ค. ํ™•์‚ฐ๊ณ„์ˆ˜๊ฐ€ 2.5ร—10-12m2/sec์—์„œ 7.5ร—10-12m2/sec๋กœ ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ, ์‹œ๊ฐ„ ์˜์กด์„ฑ์„ ๊ณ ๋ คํ•˜์ง€ ์•Š์€ ๊ฒฐ์ •๋ก ์  ๋ฐฉ๋ฒ•์—์„œ๋Š” 26.8๋…„์—์„œ 8.6 ๋…„์œผ๋กœ, ์‹œ๊ฐ„์˜์กด์„ฑ ๊ฒฐ์ •๋ก ์  ๋ฐฉ๋ฒ•์—์„œ๋Š” 76.0๋…„์—์„œ 21.3๋…„ ์œผ๋กœ ๊ฐ์†Œํ•˜์˜€๋‹ค. ๋˜ํ•œ ๊ณ ์ •์‹œ๊ฐ„ ํ™•๋ฅ ๋ก ์ ์ธ ๋ฐฉ๋ฒ•์—์„œ๋Š” 13.2 ๋…„์—์„œ 4.7๋…„์œผ๋กœ, ์‹œ๊ฐ„์˜์กด ํ™•๋ฅ ๋ก ์  ๋ฐฉ๋ฒ•์—์„œ๋Š” 38.5๋…„์— ์„œ 9.8๋…„์œผ๋กœ ๊ฐ์†Œํ•˜์˜€๋‹ค. ์—ผํ™”๋ฌผ ํ™•์‚ฐ๊ณ„์ˆ˜๊ฐ€ 300% ์ฆ๊ฐ€ํ•  ๋•Œ, ๋‚ด๊ตฌ์ˆ˜๋ช…์€ 32.1%(๊ณ ์ • ๊ฒฐ์ •), 28.0%(์˜์กด ๊ฒฐ์ •), 35.6% (๊ณ ์ • ํ™•๋ฅ ), 25.5%(์˜์กด ํ™•๋ฅ ) ์ˆ˜์ค€์œผ๋กœ ๊ฐ์†Œํ•˜์˜€๋‹ค.

4.2.2. ํ”ผ๋ณต๋‘๊ป˜์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์ˆ˜๋ช…

Fig. 7์—์„œ๋Š” ํ”ผ๋ณต๋‘๊ป˜์˜ ๋ณ€ํ™”์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์ˆ˜๋ช…์˜ ๋ณ€ํ™”๋ฅผ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ๋‹ค.

Fig. 7

Service life with varying cover depth

JKSMI-20-65_F7.jpg

ํ”ผ๋ณต๋‘๊ป˜๊ฐ€ 75 mm์—์„œ 125 mm๋กœ ์ฆ๊ฐ€ํ•˜๋ฉด์„œ ๋‚ด๊ตฌ์ˆ˜๋ช…์€ ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ๋‚ด๊ตฌ์ˆ˜๋ช…์€ ํ™•์‚ฐ๊ณ ์ • ๊ฒฐ์ •๋ก ๋ฐฉ๋ฒ•์—์„œ๋Š” 26.8๋…„์—์„œ 71.6๋…„์œผ๋กœ, ์‹œ๊ฐ„ํ™•์‚ฐ์„ฑ ๊ฒฐ์ •๋ก  ๋ฐฉ๋ฒ•์—์„œ๋Š” 76.0 ๋…„์—์„œ 222.4๋…„์œผ๋กœ ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ํ™•๋ฅ ๋ก ์ ์ธ ๋ฐฉ๋ฒ•์—์„œ ๋Š” 13.2๋…„์—์„œ 38.1๋…„์œผ๋กœ(๊ณ ์ • ํ™•๋ฅ ), 38.5๋…„์—์„œ 120.0๋…„(์˜ ์กด ํ™•๋ฅ )์œผ๋กœ ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ํ”ผ๋ณต๋‘๊ป˜๊ฐ€ 166.7% ์ฆ๊ฐ€ํ•  ๋•Œ ๋‚ด๊ตฌ์ˆ˜๋ช…์€ 267~311%๋กœ ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ๊ฐ๊ฐ 267.2%(๊ณ  ์ •๊ฒฐ์ •), 292.6%(์˜์กด๊ฒฐ์ •), 288.6%(๊ณ ์ •ํ™•๋ฅ ), 311.7%(์˜์กด ํ™•๋ฅ ) ์ˆ˜์ค€์œผ๋กœ ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜์˜€๋Š”๋ฐ, ์ด๋Š” ํ”ผ๋ณต๋‘๊ป˜๊ฐ€ ๋งค์šฐ ๋ฏผ ๊ฐํ•˜๊ฒŒ ๋‚ด๊ตฌ์ˆ˜๋ช…๊ณผ ๊ด€๋ จ ์žˆ์Œ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค.

4.2.3. ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์ˆ˜๋ช…

์ผ๋ฐ˜์ ์ธ ๋น„๋ง๋Œ€์กฐ๊ฑด(5.0 kg/m3)์˜ ์ˆ˜์ค€์—์„œ 3๋ฐฐ๋กœ ํ‘œ๋ฉด์—ผ ํ™”๋ฌผ๋Ÿ‰์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ๋‚ด๋ถ€๋กœ ์œ ์ž…๋˜๋Š” ์—ผํ™”๋ฌผ ์ด์˜จ์ด ์ฆ๊ฐ€ํ•˜ ์—ฌ, ๋‚ด๊ตฌ์ˆ˜๋ช…์ด ๊ฐ์†Œํ•œ๋‹ค. ํ‘œ๋ฉด ์—ผํ™”๋ฌผ๋Ÿ‰์ด 5.0 kg/m3์—์„œ 15.0 kg/m3์œผ๋กœ ์ฆ๊ฐ€ํ•  ๊ฒฝ์šฐ, ๊ณ ์ •ํ™•์‚ฐ ๊ฒฐ์ •๋ก ์  ๋ฐฉ๋ฒ•์—์„œ๋Š” 26.8๋…„์—์„œ 12.7๋…„์œผ๋กœ, ์‹œ๊ฐ„ํ™•์‚ฐ ๊ฒฐ์ •๋ก ์  ๋ฐฉ๋ฒ•์—์„œ๋Š” 76.0 ๋…„์—์„œ 31.1๋…„์œผ๋กœ ํฌ๊ฒŒ ๊ฐ์†Œํ•˜์˜€๋‹ค. ํ™•๋ฅ ๋ก ์ ์ธ ๋ฐฉ๋ฒ•์—์„œ๋Š” ๊ณ ์ •ํ™•์‚ฐ์ธ ๊ฒฝ์šฐ 13.2๋…„์—์„œ 7.2๋…„์œผ๋กœ ๊ฐ์†Œํ•˜์˜€์œผ๋ฉฐ, ์‹œ๊ฐ„ ์˜์กด์„ฑ ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ๊ณ ๋ คํ•  ๊ฒฝ์šฐ 38.5๋…„์—์„œ 17.5๋…„์œผ๋กœ ํฌ๊ฒŒ ๊ฐ์†Œํ•˜์˜€๋‹ค.

ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰์ด 300% ์ฆ๊ฐ€ํ•  ๊ฒฝ์šฐ, ๋‚ด๊ตฌ์ˆ˜๋ช…์€ ๊ฐ๊ฐ 47.4% (๊ณ ์ • ๊ฒฐ์ •), 40.9%(์˜์กด ๊ฒฐ์ •), 54.5%(๊ณ ์ • ํ™•๋ฅ ), 45.5%(์˜ ์กด ํ™•๋ฅ ) ์ˆ˜์ค€์œผ๋กœ ๊ฐ์†Œํ•˜์˜€๋‹ค. Fig. 8์—์„œ๋Š” ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์ˆ˜๋ช…์˜ ๋ณ€ํ™”๋ฅผ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ๋‹ค.

Fig. 8

Service life with varying surface chloride content

JKSMI-20-65_F8.jpg

์ด์ƒ์˜ ํ•ด์„์—์„œ๋Š” ๋‹ค์–‘ํ•œ ์˜ํ–ฅ์ธ์ž(๊ธฐ๋ณธ ์—ผํ™”๋ฌผ ํ™•์‚ฐ๊ณ„ ์ˆ˜, ํ”ผ๋ณต๋‘๊ป˜, ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰)๋“ฑ์„ ๊ณ ๋ คํ•˜์—ฌ ๊ฒฐ์ •๋ก  ๋ฐ ํ™•๋ฅ ๋ก  ์  ํ•ด์„์„ ์ˆ˜ํ–‰ํ•˜์—ฌ ๋‚ด๊ตฌ์ˆ˜๋ช…์„ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ํŠนํžˆ ๊ฐ ๋ฐฉ๋ฒ•์— ๋Š” ์‹œ๊ฐ„์˜์กด์„ฑ ํ™•์‚ฐ๊ณ„์ˆ˜์™€ ๊ณ ์ •ํ˜• ํ™•์‚ฐ๊ณ„์ˆ˜๋ฅผ ๊ฐ๊ฐ ๋ถ„๋ฅ˜ํ•˜์—ฌ ๋„์ถœ๋œ ๋‚ด๊ตฌ์ˆ˜๋ช…์˜ ๋ณ€ํ™”๋ฅผ ๋ถ„์„ํ•˜์˜€๋‹ค.

๋‚ด๊ตฌ์ˆ˜๋ช…์— ๋Œ€ํ•œ ์˜ํ–ฅ์ธ์ž์˜ ๋ฏผ๊ฐ๋„๋ฅผ ๋ถ„์„ํ•˜๊ธฐ ์œ„ํ•ด ์˜ํ–ฅ ์ธ์ž๋“ค์˜ ์ฆ๊ฐ€๋น„์™€ ๋‚ด๊ตฌ์ˆ˜๋ช…์˜ ๋ณ€ํ™”๋ฅผ ์ •๊ทœํ™”ํ•˜์—ฌ ๋ถ„์„ํ•˜์˜€ ๋‹ค. Fig. 9์—์„œ๋Š” ๊ฐ ์˜ํ–ฅ์ธ์ž์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์ˆ˜๋ช…์˜ ๋ณ€ํ™” ๋น„์œจ์„ ๋„์‹œํ•˜์˜€์œผ๋ฉฐ, ๊ฐ๊ฐ์˜ ๊ฒฐ๊ณผ๋ฅผ ์„ ํ˜•ํšŒ๊ท€๋ถ„์„ํ•˜์—ฌ ๊ธฐ์šธ ๊ธฐ๋ฅผ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰์— ๋Œ€ํ•œ ํšŒ๊ท€๋ถ„์„ ๊ฒฐ๊ณผ๋Š” 2์ฐจ ํ•จ์ˆ˜์— ๊ฐ€๊นŒ์› ์œผ๋‚˜, ๋น„๊ต์  ๋งŒ์กฑํ• ๋งŒํ•œ ๊ฒฐ์ •๊ณ„์ˆ˜(R2)์„ ๊ฐ€์ง€ ๊ณ  ์žˆ์—ˆ์œผ๋ฏ€๋กœ ์„ ํ˜•ํšŒ๊ท€๋ถ„์„์œผ๋กœ ์˜ํ–ฅ๋„๋ฅผ ๋™์ผํ•˜๊ฒŒ ํŒŒ์•…ํ•˜ ์˜€๋‹ค.

Fig. 9

Normalized parameters and changing service life

JKSMI-20-65_F9.jpg

ํšŒ๊ท€๋ถ„์„๊ฒฐ๊ณผ๋Š” Table 3์— ๋‚˜ํƒ€๋‚ด์—ˆ์œผ๋ฉฐ ๊ฐ ๊ธฐ์šธ๊ธฐ(A)์˜ ํ‰๊ท ์„ Fig. 10์— ๋„์‹œํ•˜์˜€๋‹ค.

Table 3

Regression analysis results for the parameters

Regression type: Y=A(X-1)+1

Case Regression results of A

Deterministic Probabilistic

Time constant Time-dependent Time constant Time-dependent

A R 2 A R 2 A R 2 A R 2

Normalized diffusion coefficient -0.375 0.902 -0.396 0.901 -0.324 0.999 -0.409 0.913
Normalized cover depth 2.429 0.990 2.816 0.993 2.845 0.997 3.126 0.997
Normalized surface chloride content -0.300 0.824 -0.328 0.884 -0.248 0.918 -0.308 0.852
Fig. 10

Comparison of gradient of parameters

JKSMI-20-65_F10.jpg

๋ชจ๋“  ์˜ํ–ฅ์ธ์ž์˜ ๊ฒฐ์ •๊ณ„์ˆ˜๋Š” ํ‘œ๋ฉด์—ผํ™”๋ฌผ์„ ์ œ์™ธํ•˜๊ณ ๋Š” 0.9 ์ด์ƒ์˜ ๋†’์€ ์ˆ˜์ค€์„ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ์—ˆ๋‹ค. ํ™•์‚ฐ๊ณ„์ˆ˜์˜ ๊ธฐ์šธ๊ธฐ ๋ฒ” ์œ„๋Š” 0.342~0.409 ์ˆ˜์ค€์œผ๋กœ, ํ”ผ๋ณต๋‘๊ป˜๋Š” 2.429~3.126์ˆ˜์ค€์œผ ๋กœ, ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰์€ 0.248~0.328 ์ˆ˜์ค€์„ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. Fig. 10 ์— ๋„์‹œ๋œ ๊ธฐ์šธ๊ธฐ๋Š” ๊ฐ ์˜ํ–ฅ์ธ์ž๊ฐ€ ๋‚ด๊ตฌ์ˆ˜๋ช…์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ ์„ ๋‚˜ํƒ€๋‚ด๋Š” ์ง€ํ‘œ๊ฐ€ ๋  ์ˆ˜ ์žˆ๋‹ค. Fig. 10์—์„œ ์•Œ ์ˆ˜ ์žˆ๋“ฏ์ด ํ”ผ๋ณต ๋‘๊ป˜์˜ ์˜ํ–ฅ์ด 2.804๋กœ ๊ฐ€์žฅ ์ปธ์œผ๋ฉฐ, ํ™•์‚ฐ๊ณ„์ˆ˜๋Š” 0.376, ํ‘œ๋ฉด ์—ผํ™”๋ฌผ๋Ÿ‰์€ 0.296์œผ๋กœ ๋น„๊ต์  ๋‚ฎ๊ฒŒ ํ‰๊ฐ€๋˜์—ˆ๋‹ค.

5. ๊ฒฐ ๋ก 

๊ฒฐ์ •๋ก  ๋ฐ ํ™•๋ฅ ๋ก ์  ๋ฐฉ๋ฒ•์— ๋”ฐ๋ฅธ ์‹œ๊ฐ„์˜์กด์„ฑ ์—ผํ™”๋ฌผ ํ™•์‚ฐ ๊ณ„์ˆ˜ ๋ฐ ์™ธ๋ถ€ ์˜ํ–ฅ์ธ์ž๊ฐ€ ๋‚ด๊ตฌ์ˆ˜๋ช…์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์„ ํ†ตํ•˜์—ฌ ๋„์ถœ๋œ ๊ฒฐ๋ก ์€ ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

  • 1) ์—ผํ™”๋ฌผ ํ™•์‚ฐ๊ณ„์ˆ˜๊ฐ€ 2.5ร—10-12m2/sec์—์„œ 7.5ร—10-12m2/sec๋กœ ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ, ๋‚ด๊ตฌ์ˆ˜๋ช…์€ 32.1%(๊ณ ์ • ๊ฒฐ์ •), 28.0%(์˜ ์กด ๊ฒฐ์ •), 35.6%(๊ณ ์ • ํ™•๋ฅ ), 25.5%(์˜์กด ํ™•๋ฅ ) ์ˆ˜์ค€์œผ๋กœ ๊ฐ์†Œํ•˜์˜€๋‹ค. ํ”ผ๋ณต๋‘๊ป˜๊ฐ€ 75 mm์—์„œ 125 mm๋กœ ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ๋‚ด๊ตฌ์ˆ˜๋ช…์€ 267~311%๋กœ ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ๊ฐ๊ฐ 267.2%(๊ณ ์ • ๊ฒฐ์ •), 292.6%(์˜์กด ๊ฒฐ์ •), 288.6%(๊ณ ์ • ํ™• ๋ฅ ), 311.7%(์˜์กด ํ™•๋ฅ ) ์ˆ˜์ค€์œผ๋กœ ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜์˜€๋Š”๋ฐ, ์ด ๋Š” ํ”ผ๋ณต๋‘๊ป˜๊ฐ€ ํ•ต์‹ฌ์ ์ธ ๋‚ด๊ตฌ์ˆ˜๋ช… ์˜ํ–ฅ์ธ์ž์ž„์„ ์•Œ ์ˆ˜ ์žˆ ๋‹ค. ๋˜ํ•œ ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰์ด 5.0 kg/m3์—์„œ 15.0 kg/m3์œผ๋กœ ์ฆ ๊ฐ€ํ•  ๋•Œ, ๋‚ด๊ตฌ์ˆ˜๋ช…์€ ๊ฐ๊ฐ 47.4%(๊ณ ์ • ๊ฒฐ์ •), 40.9%(์˜์กด ๊ฒฐ์ •), 54.5%(๊ณ ์ • ํ™•๋ฅ ), 45.5%(์˜์กด ํ™•๋ฅ ) ์ˆ˜์ค€์œผ๋กœ ๊ฐ ์†Œํ•˜์˜€๋‹ค.

  • 2) ์˜ํ–ฅ์ธ์ž์˜ ์ฆ๊ฐ€๋น„์œจ๊ณผ ๋‚ด๊ตฌ์ˆ˜๋ช…์˜ ๋ณ€ํ™”๋น„์œจ์„ ๊ณ ๋ คํ•˜๋ฉด ๊ฐ ์˜ํ–ฅ์ธ์ž์˜ ๋ฏผ๊ฐ๋„๋ฅผ ๋น„๊ตํ•  ์ˆ˜ ์žˆ๋‹ค. ํ™•์‚ฐ๊ณ„์ˆ˜์˜ ๋ณ€ํ™” ๋”ฐ๋ฅธ ๋‚ด๊ตฌ์ˆ˜๋ช…์˜๊ธฐ์šธ๊ธฐ ๋ฒ”์œ„๋Š” 0.342~0.409 ์ˆ˜์ค€์œผ๋กœ, ํ”ผ ๋ณต๋‘๊ป˜๋Š” 2.429~3.126์ˆ˜์ค€์œผ๋กœ, ํ‘œ๋ฉด์—ผํ™”๋ฌผ๋Ÿ‰์€ 0.248~0.328 ์ˆ˜์ค€์„ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๊ธฐ์šธ๊ธฐ ๋ณ€๋™์„ฑ์—์„œ๋„ ํ”ผ๋ณต๋‘๊ป˜์˜ ๊ฒฝ ์šฐ ํ™•์‚ฐ๊ณ„์ˆ˜ ๋ฐ ํ‘œ๋ฉด์—ผํ™”๋ฌผ์— ๋น„ํ•˜์—ฌ 8~10๋ฐฐ์ •๋„์˜ ์˜ํ–ฅ ๋„๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

๊ฐ์‚ฌ์˜ ๊ธ€

์ด ๋…ผ๋ฌธ์€ 2015๋…„๋„ ์ •๋ถ€(๋ฏธ๋ž˜์ฐฝ์กฐ๊ณผํ•™๋ถ€)์˜ ์žฌ์›์œผ๋กœ ํ•œ ๊ตญ์—ฐ๊ตฌ์žฌ๋‹จ์˜ ์ง€์›์„ ๋ฐ›์•„ ์ˆ˜ํ–‰๋œ ๊ธฐ์ดˆ์—ฐ๊ตฌ์‚ฌ์—…์ž„(No. 2015 R1A5A1037548).

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