ª Œª Œ 26ƒ 2C Á 2006 3œ pp. 99~108 ª n» x The Experimental Study on Electrokinetic Injection Improvement of Low Permeable Ground ½ Áw Á½» Kim, Soo-SamÁHan, Sang-JaeÁKim, Ki-Nyun Abstract In this study a series of bench scale test are conducted to increase the undrained shear strength of clayey soils using by Electro-kinetic injection stabilization method. The sodium silicate was injected in anode reservoir and its concentration was changed with 500, 1000, 1500, 2000, 2500mM for configuration of applicability of Electro-kinetic injection stabilization method. Also, the treatment time and electric gradient was changed to acquire the optical influence factors. For increasing the shear strength to maximum values, the calcium chloride and aluminium hydroxide, which concentration was changed with 50, 250, 500, 750, 1000mM, were added at anode reservoir for 5 days after the treatment of sodium silicate in 5 days as the 2nd additives. The test of results in determination of sodium silicate concentration show that the undrained shear strength at each point had a tendency to converge into a constant value when the concentration of sodium silicate came to 1000mM and above. The maximum shear strength increasement was 800% compared with initial value. After a series of test, the electric gradient and treatment time for application of electric fielld were 1V/cm and 6 days. In case of 2nd additives test, the concentration for maximum shear strength is 250mM in all additives and the effects of shear strength improvement was developed approximately 20~30% in comparison to addition of single injection material. Keywords : Clayey soils, Electro-kinetic injection stabilization method, Undrained shear strength m j» w,» y ü x ww. w ³ ù p wš y(500, 1000, 1500, 2000, 2500mM) g» y» q w š,» w q w» w 2 (2, 4, 6, 8, 10 )» w x 0.25, 0.5, 1.0, 1.5, 2.0V/cm y k x w. w ye y 2 w ƒ z q wš w. w ³ ùp (1000mM) 5 w z 2 50, 250, 500, 750, 1000mM y g 5 w. ³ ùp x 1000mM w w,» 800% j z ƒ ùkû.»» x 1V/cm,» 6 ƒeƒ w ùkû. ye y 2 w, 250mM w w ùkû, ³ ùp w 20~30% z ƒ w. w : m,» y œ, 1. m š en q(permeation Grouting) œ, p 10 1 ~10 cm/sec n 3 w, n ƒ 10 5 cm/sec w p m, en q w ƒ j š w q ƒ w ((Dise et al., 1994; * z Áw w m y œw (E-mail : kimss@hanyang.ac.kr) ** z Áw w m y œw (E-mail : hansj@hanyang.ac.kr) ***w w m y œw w (E-mail : kkn1976@ihanyang.ac.kr) 26ƒ 2C 2006 3œ 99 Luehring et al., 2001; Thevanayagam et al., 2002). w p m w w» en q w»ƒ, w (Thevanayagam and Jia, 2003). n ƒ w» x š. w n j» w š en j,
» y(electro-kinetic Injection Stabilization)» w š ³ ùp (Sodium Silicate) w x y t wš. x ¾» w» œw y œw š p,» n x w k ù y š (Alshawabkeh et al., 2003). w r, œw d» n»áyw œ, š y (Cementation) w ƒ ƒw š (Madshus and Janbu, 1984; Mitchell and Klainer, 1987; Ozkan et al., 1999; Thevanayagam and Jia, 2003; Alshawabkeh et al., 2003). w x ¾ w (,, ) p q w wš x. ü x x(bench scale test) w w e (,»» ) y q wš w, x mw z w» y» š wš w. 2.»» š y» y» n» w, / y en, w x k». sym ƒw, w w x w (Michell 1993): (i) ƒ (+) (-) (» n). (ii) w (+) (-) w ( ). (iii) w (-) (+) w ( ). ƒ w ph y y wš, mw, w. mù p w» n 10 5 cm/s/v/cm,» n (Michell, 1993). w š w, w w q w w n û p y w. w, w, k, w ph fp w, y w.» y» mw œ (Ÿ) w» n w (+) (-) ƒ ( ) w y w g q k. 1» y» ùkü.» ƒ ƒ w» 1.»» 2. ³ ùp y (Shan & Shroff, 1985) 100 ª Œª Œ
, j» w. w y œ š w w ³ ùp (SiO 2 ÁNa 2 O) (Karol, 2003). w y (Al(OH) 3 ), y (Fe 2 O 3 ), ye (CaO), (H 3 PO 4 ), ³ ùp (SiO 2 Á Na 2 O) 1V/cm w» w w w» x ww (½», 2005), ³ ùp w m š y z ƒ ùkû. ³ ùp w. ³ ùp e w e (The Ratio of Silica/Alkali, n)» w, m n 3~4 w q, š y(gel) e e w ù x ( 2, Shan & Shroff, 1985). 1 2 ³ Monomer g x w(sol) w w(gel) ³ ùp w w, w ³ ùp ye w (1) w ³ x. SiO 2 ÁNaO 2 + CaCl 2 + H 2 O Ca(OH) 2 + SiO 2 Á2NaCl (1) w x y p j x w š, w k w (Karol, 2003). w ³ ùp ye ye (Ca(OH) 2 ) m w š y w w w. 3. ye ƒ w š y (Van Impe, 1989) Gray and Schlocker(1969) Gray(1970), ü w š k x w. š ye y 2 ƒ w ƒ ³ ùp wì w ³ ù p w wš e e w š y z w. 3.» y x 3.1 p 3.1.1 ³ ùp (Sodium Silicate) m œ ³ ùp w k w w» y x w. ³ ùp y³ e w e ³ w, ƒ. 3.1.2 ye (Calcium Chloride) yw CaCl 2 š e (Ca) (Cl) yw yw p r, 111, 772 o C, 2.15, ò 1600 o C ¼ ƒ ƒƒ ƒ š (Orthorhombic System) w. ye w ù» w w ƒ w» y œ Ÿ w, p y œ ƒ (Ingles & Metcalf, 1972). ye w w, j š y w ƒ ƒw. 3.1.3 y (Aluminium Hydroxide) yw Al(OH) 3, y, 78.0, (Monoclinic System) ƒ š. ½ p(gibbsite), y w y e ew» p ƒ š. m e w š y z ùkü, 2 ƒ z» w. 3.2 p w yw, p q w» w y ƒ ûš w, Kaolinite w 97% EPK-Kaolinite w w., w š w sy w x» w k w» w w 80% sy k z w w w. t 1 EPK-Kaolinite p ùkü. Gs LL (%) PL (%) Ch (cm 2 /sec) w opt (%) t 1. EPK-Kaolinite p Initial ph CEC (cmol/kg) Mineral content (X-ray diffraction) Specific surface area (m 2 /g) 2.65 64 26 3.03Ü10-3 31.0 5.8 4.5 Kaolinite(Al 2 O 3, 2Sio 2, 2H 2 O)-97% 22.1 26ƒ 2C 2006 3œ 101
3.3» x e x x e,. 5ƒ x w ƒƒ ƒƒ ( 4). ƒ e z t» w w, e d w d (Passive electrode) ew, ph» d w» w ƒ. 4.» y (cm) w, x ƒ ü» w 0.5cm Ì š w. x w» w k p(mariotte bottle) ew, (Overflow)ƒ ƒ w w. ù wp e p e ì. 3.3.1» w x t 2~t 4 EPK-Kaolinite w 15ƒ» y x w. Test 1~Test 5 (t 2), Sodium Silicate» (50mM, ½», 2005) w x w, 500mM, 1M, 1.5M, 2M, 2.5M w x w. š w š z q w» w. Test 6~Test 10(t 3) Test 11~Test 15(t 4), t 2. x (Test 1~Test 5) Variable factors Injection agent Test No. Anode Cathode Test 1 Sodium Silicate(500mM) Test 2 Test 3 Test 4 Test 5 Sodium Silicate(1M) Sodium Silicate(1.5M) Sodium Silicate(2M) Sodium Silicate(2.5M) Deionized Water t 3. x (Test 6~Test 10) Fixed factors Volt (V/cm) Duration (days) 1 10 Days Fixed factors Variable factors Duration(days) Injection agent Volt(V/cm) 10 Days Test No. Anode Cathode Test 6 0.25 Test 7 0.5 Sodium Deionized Test 8 Silicate 1 Water (1M) Test 9 1.5 Test 10 2 t 4. x (Test 11~Test 15) Fixed factors Variable factors Volt (V/cm) Injection agents Duration(days) 1.0 Test No. Anode Cathode Test 11 Test 12 Sodium Deionized Test 13 Silicate Water (1M) Test 14 Test 15 2 Days 4 Days 6 Days 8 Days 10 Days (0.25V/cm~2V/cm)» (2 ~10 ) y g š w» wš w. x, ph,, d w, x z w ( x) d w. 3.3.2 w w» x t 5 t 6 w w 80% EPK-Kaolinite, x š Test No. Test 16 Test 17 Test 18 Test 19 Test 20 1st Shot Sodium Silicate(1M) t 5. x (Test 16~Test 20) Variable factors Fixed factors Injection agent Volt(V/cm) Duration(days) Anode 2nd Shot Calcium Chloride(50mM) Calcium Chloride(250mM) Calcium Chloride(500mM) Calcium Chloride(750mM) Calcium Chloride(1000mM) Cathode Deionized Water 1 5 Days 5 Days 102 ª Œª Œ
표 6. 실험조건(Test 21~Test 25) Variable factors Injection agent Anode Test No. 1st Shot Sodium Silicate(1M) Aluminium Hydroxide(250mM) Aluminium Hydroxide(500mM) Aluminium Hydroxide(750mM) Aluminium Hydroxide(1000mM) Test 21 Test 22 Test 23 Test 24 Test 25 Cathode 2nd Shot Aluminium Hydroxide(50mM) 자는 1V/cm의 전기경사와 양극부에 주입하는 1M의 규산나 트륨 농도이다. 염화칼슘과 수산화알루미늄의 첨가 농도에 따른 전단강도 개량 정도를 파악하기 위해 농도를 50mM, 250mM, 500mM, 750mM 및 1000mM로 변화시켰으며, 전 기삼투에 의해 규산나트륨을 5일 동안 이동시킨 후 나머지 5일 동안 농도를 달리한 염화칼슘과 수산화알루미늄을 첨가 하였다. 실험 종료 후에는 각 지점별로 베인 전단시험기를 이용해 비배수 전단강도, ph 및 전기전도도를 측정하였다. 또한 이 동된 규산나트륨과 이들 첨가제의 반응에 의한 고결화 작용 이 압밀특성에 미치는 영향을 판단하기 위해 최고 전단강도 가 발현되는 지점에서의 시료를 채취하여 표준압밀시험을 실 시하였다. 동전기 주입 영향인자 산정 실험 결과 4.1.1 주입제 농도에 따른 강도 특성 동전기 주입 실험 종료 후, 양극으로부터 총 5지점으로 나누어 각 지점 당 4회의 베인 전단실험을 실시하였다(그림 그림 7은 주입제의 농도변화에 따라 측정된 평균 강도값 과 함수비의 변화로 인해 발생하는 강도값을 비교하여 나타 낸 그래프이다. 그림에 나타난 바와 같이, 농도 1000mM ~2500mM에서 비슷한 강도 증진효과를 나타났으며, 함수비 의 감소가 크지 않았음에도 불구하고 강도값이 크게 발생하 였다. 따라서 1000mM 이상의 주입제는 강도증진효과에 큰 영향을 미치지 못함을 알 수 있었다. 5). 그림 5. 베인 전단실험 전경 2C 2006 3 5 Days 5 Days 그림 6. 주입제 농도에 따른 강도분포 4.1 26 Deionized Water 1 하는 경향이 나타났다. 따라서 주입농도 1000mM을 최적의 주입농도로 파악할 수 있었다. 4. 실험 결과 분석 및 고찰 그림 6은 실험 종료 후, 총 시료길이를 5등분하여 실내 베인 실험을 실시한 결과를 주입농도별로 나타낸 그래프이 다. 그 결과, 전 영역에서 10~50배 정도의 강도증진효과가 나타났으며, 주입 농도 1000mM 이후로는 강도 값이 수렴 第 卷第 號 年 月 Fixed factors Volt(V/cm) Duration(days) 그림 7. 주입제의 농도와 함수비에 따른 강도의 변화 4.1.2 전압경사에 따른 강도 특성 그림 8은 동전기 처리 후, 전압경사에 따른 양극으로부터 위치 별(3, 9, 15, 21, 27cm)로 103 강도 분포를 나타낸 그래
v. ùkù, 1.0V/cm l ƒ e w w. 10.» s(test 11~15) 8. s(test 6~10) 9 y, ƒ x d s³e w y w w w z, w v., ƒ ƒw» w z ƒ j ùkû, 1.0V/cm j. w w f. w 1.0V/cm ƒ ƒw, w w š w w. w ksl w (+) (-) (Eyholt, 1992; Acar and Alshawabkeh, 1993). 11 z» y d w y w k z ùkü v. 9. w y(test 6~10) w, w w z wš, w š w, 1500~3500% z ƒ ùkû. w ( 8, 9) l x 1.0V/cmƒ»» q w. 4.1.3» p 10» y k x z ü x w ùkü. x,» ¼ z ƒ ùkû. w ƒ¾ ƒ w w ùkû,» n w w w ƒ» w.» n 104 11.» y(test 11~15),» ƒ w ùkü. w, ƒ»,» 10 wš z ƒ j ùkû. w w z wš 20~40 ƒ ƒw š w, x e» ƒ š x» w q w. 4.2 w w» x 4.2.1 ye ƒ» 12 ye ³ ùp w 2 ƒ w, ye w z ùkü., ye ƒ 250mM, ƒ ƒw. ù ye ƒ 250mM w w w. ye ƒ ƒ w, e ü m ³ ùp š y wwš, e y e ª Œª Œ
12. ye ƒ s(test 16~20) w». 13 ye 250mM w z, 10 ³ ùp ƒw 5 ³ ùp 1 wš, 2 5 ye ƒw, w v. 14. y ƒ s (Test 21~25) w, s³ 25% ƒ ƒ. p 34% ƒ ƒw ( 15). w» (EM) w w y e. 13. ye ƒ» w, ye w z» ³ ù p w 20% ƒ ƒw x. (1) w, ³ ùp m w 2 ƒ ye w ye x š m ü 2 šy ƒ x». 4.2.2 y ƒ» 14 y ³ ùp z, 2 ƒ w ü s xk ù kü. y ƒ ƒ 250mM w d w. y 250mM w, û w w w w». y 250mM w q. w, ³ ùp ƒw 15. y ƒ» w 4.2.3 p y š yù ƒ w š y ƒ wš z w w (σ o ) y w (Bjerrum, 1967). w 2 ƒ w m š y w w» w ƒƒ x w w w (C c ) w, 16 ùkù y ƒw (=1.8kgf/cm )ƒ ye ƒw 2 (σ C =0.4kgf/ cm ) 4.5 j w w 2 ùkû, ƒƒ (C c ) 0.42~0.47 w w. w,» w w w (σ C =0.13kgf/ cm )» w ƒƒ 2 3 ( ye ƒ), 14 ( y ƒ) j w w ùkû. 16 ye y ƒ» w š y z w m w w w ƒz ƒ ùkû» q w. 26ƒ 2C 2006 3œ 105
ƒ w ƒ Skempton(1953) w (8) w. ƒƒ w ƒ ( p) w š j k, y ƒ w. 16. w» w š p 4.3» œ w œ p» œ œ w z wš w.» œ w m w w œ w w., x w œ w» w (2)~ (5) Barron(1948)» w, w (d e )» 30cm w. c ut = c uo + ( c u p) p U ε = 0.11 + 0.0037 P.I c u p (7) (8)», c uo :» c u /p : ƒ p : ƒ U ε : P.I :» œ w w w k wš w g, ƒ w w 30cm» ùkû. w 90% š ƒ wš, ƒƒ ƒ w, w w ƒw ƒw ( 17). U = 1 exp λ λ 8T h = ----------- F( n) ( ) n 2 3n F( n) ------------ ln 2 1 = n n 2 ( ) --------------- 1 4n 2 (2) (3) (4) d e n = ----- d w qx y j» w (6) w Hansbo (1979)ƒ w ƒ w. w ƒ w ex PDB(Plastic Drain Board) e 10 0.38cm. 2( a+ b) d w = ----------------- π, ƒ (d w ) 6.6cm, 90% w (T h ) 0.25 š, (C h ) 3.03 10 3 cm 2 /sec, ƒ w s³ 0.86 w. ƒƒ ww (1, 5, 10, 15, 20, 30, 40ton/m ) w ƒw 2 (7) Yamanouchi(1982)ƒ w ³ m w w ƒ w., m z w w (5) (6) 106 17.» œ œ (I) ww» w ƒ w, 2» œ w ( 18), œ z 10ton/m 2 j w z ƒ ùkû, 10» œ 18.» œ œ (II) ª Œª Œ
w 19.5ton/m 2 j w ƒ ùkû. 5. n w» w (³ ) en j,»» w q w» w w. ƒ x w y x mw y p w. 1. n» y z w w x, ³ ùp ƒ 1000mM ƒ x. w w» y z, w ƒ ƒw wš» 800% z ƒ ùkû. w w ³ ùp š y z š, š n» y œ y w, ³ ùp 1000mM. 2.» x, 1V/cm û» ƒw» w w ƒƒ, 1V/cm» w» ƒ ƒw wš z w s ùkþ.» y œ w» y œ x m x w. 3.»» x,» w ƒw ù, z ƒ w w w w ùkü. y w ³ ùp w» q. w»» ƒ 50%, š s³ w, 2.53cm/day ùkû. k ¼»» ƒ w. 4. jš w ye, y ƒ», w yw z j ùkþ. p, t x ww, ƒw yw w w (σ c ) j ƒ, ³ ùp 1 w z 2 ye w ƒ ye w 4.5 w w z ùkþ. š y z w w» yw ye q w. (C c ) ƒw yw w y w. 5. q w ù m wƒ ƒ w,» y œ œ z w œ. m ww 2004 w» w w,. š x ½» (2005) Electro-kinetic w m w x, w, w w. Acar Y. B., Alshawabkeh A. N. (1993) Principles of electrokinetic remediation. Environmental, Science and Technology, Vol. 27, No. 13, pp. 2638-2647. Alshawabkeh A. N., Sheahan T. C., Xingzhi Wu. (2003) Coupling of electrochemical and mechanical processes in soils under DC fields, Mechanics of Materials. Barron, R. A. (1948) Consolidation of fine-grained soil by drain well, Geotextile and Geomembranes, Vol. 10, No. 3. Bjerrum, L. (1967) Engineering geology of normally consolidated marine clays as related to settlement of buildings, Geotechnique, Vol. 17, No. 2, pp. 82~118. Dise, K., M. G. Stevens, and J. L. Von Thun. (1994) Dynamic compaction to remediate liquefiable embankment foundation soils, GPS No. 45, ASCE, Reston, VA. Eykholt G. R. (1992) Driving and Complicationg Features of the Electrokinetic Treatment of Contaminated Soils, Ph. D Thesis, University of Texas at Austin, pp. 269. Hansbo, S. (1979) Consolidation of clay by band-shaped prefabricated drains, Ground Engineering, Vol. 12, No. 5, pp. 16~25. Ingles, O. G. & Metcalf, J. B. (1972) Soil Stabilization, Butterworths Pty. Limited, Sydney. Karol, R. H. (2003) Chemical Grouting and Soil Stabilization-3rd edition, Revised and Expanded, Marcel Dekker, INC., New York. Luehring, R., Snorteland, N., Stevens, M., and Mejia, L. (2001) Liquefaction mitigation of a silty dam foundation using vibrostone columns and drainage wick: A case history at salman lake dam, Proc. Dam Safety Conference, Sept. 11-15, Colorado. Madshus, P. A. and Janbu, N. (1984) Improvement of quick clay by electrolysis, Scandinavian Geotechnical Meeting, Sweden, Bulletin 17. Mitchell, J. K. and Klainer, E. (1987) Chemical stabilization of landslides, Research Report, UCB-ITS-RR-87-16, Institute of Transportation Studies, University of California, Berkeley. Mitchell, J. K. (1993) Fundmentals of soil behavior-2rd edition, Wiley Interscience, pp. 256~258. Ozkan. S, Gale. R. J, Seals. R. K. (1999) Electrokinetic stabilization of kaolinite by injection of Al and PO 4 3 ions, Ground Improvement. Volume GI03. Issue 04. Shan and Shroff (1985) Resin grout system for rock treatment, Proc. Indian Geotech. Conference, Roorkee Sarita, Prakashan, Meerut, pp. 203~208. Skempton, A. W. (1953) Soil mechanics in relation to geology, Proc. of Yorkshire Geological Soc., Vol. 29, pp. 33. 26ƒ 2C 2006 3œ 107
Thevanayagam, S., Martin, G. R., and T. Shenthan (2002) Ground remediation for silty soils using composite stone columns(task 150 C104E), Seismic Vulnerability of the highway System, FHWA Contract # DTFH 61-98-C-00094. Thevanayagam, & Jia (2003) Electro-osmotic grouting for liquefaction mitigation in silty soils, ASCE Special Technical Publication, No. 120. Van Impe, W. F. (1989) Soil improvement techniques and their evolution, A.A.Balkema, Rotterdam. Yamanouchi, T., Miura, N. (1982) Soil improvement with quicklime and filter fabric, ASCE, Vol. 108, No. GT7, pp.35~46. ( : 2005.9.26/ : 2005.10.27/ : 2005.10.27) 108 ª Œª Œ