Soil-Water Characteristics of Huai-an Expensive Soil

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Ambrose Douglas Pierce
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1 JOURNAL OF SHANGHAI UNIVERSITY (NATURAL SCIENCE) Vol. 20 No. 2 Apr DOI: /j.issn , (, ) :, 3,, MPa.,,, 100 MPa, ;., MPa.,,, ;,. : ; ; ; ; : TU 443 : A : (2014) Soil-Water Characteristics of Huai-an Expensive Soil WU Yi-gao, SUN De-an (Department of Civil Engineering, Shanghai University, Shanghai , China) Abstract: To investigate soil-water characteristic curve (SWCC) of Huai-an expanded soil, three different suction control or measurement methods are used. These are the pressure plate method for low suction, the filter paper method, and the vapor equilibrium technique for high suction. SWCC shows obvious hysteresis features during drying and wetting circle in the low suction range. When the suction is greater than 100 MPa, the hysteresis effect of SWCC disappears, and the drying and wetting curves are almost the same. Test data of SWCC, obtained using the filter paper method, are between the main drying and wetting SWCCs. The tendency of SWCC in the high suction by the vapor equilibrium method shows that the water content is almost zero when the suction is close to MPa. Based on the result of expanded soils by using filter paper, when SWCC is expressed with degree of saturation and suction relation, SWCC with higher dry density is on the upper side in the relatively low suction range, and the dry density has no effect on SWCC in the relatively high suction range. Key words: compacted expensive soil; pressure plate method; filter paper method; vapor equilibrium method; soil-water characteristic curve (SWCC), (G2) (G25, ) (G2513). ( ), : : ( ) : (1962 ),,,,. sundean@shu.edu.cn

2 2, : ,. 92 km,.,,..,.,,,,,,.,. [1].,. Fredlund [2], -.,.,, 1.5 MPa [3]..,,. [4], ; [5], ; [6],,.,.,, , 2 m, 1. [7],. 1 Table 1 Physical indexes of Huai-an expensive soil G s 2.74 w/% ρ/(g cm 3 ) <0.005 mm/% w L/% w P/% I P w opt/% 14.5 ρ d,max /(g cm 3 ) 1.77 δ ef /% 49.00

$g, Æ 252 1.2 1 20 ò Á ì Øå {Á ^ ì {I GCTS úi) SWCC-150 èya Øå ( ã 1).$ LockLock Ý! Ý 0.000 1 g >f Ú ð ð ( ã 2)[8]. ã 1 {IGCTSúi SWCC-150èYA Øå Fig.

3 g, Æ ò Á ì Øå {Á ^ ì {I GCTS úi) SWCC-150 èya Øå ( ã 1). ã Øå e c ^u=pøå, ~ >è ÚüY+ YÞ, ±B* üyyþ, äáå Ä²ï. È { ^ Ü ) Whatman 42 ÒÈ!LockLock Ý! Ý g >f Ú ð ð ( ã 2)[8]. ã 1 {IGCTSúi SWCC-150èYA Øå Fig. 1 SWCC-150 soil-water characteristics pressure instrument produced by GCTS ã 2 CkÈ Úè LockLockÝ Fig. 2 LockLock boxes with filter paper and soil sample ã 3 Ckè Ú ÚíM 4ZHì Fig. 3 Sealed glass container with saturated salt solution and soil samples ð²ï{ ^ ) A» 180 mm ÀæZHì! «ÚíM Ú

4 2, : 253 ( 3). RH(%) [9],, 9 ( 2). 2 (20 C) Table 2 Saturated salt solution, RH and corresponding suction (20 C) RH/% /MPa LiBr LiCl H 2O CH 3COOK MgCl 2 6H 2O K 2CO KI NaCl KCl K 2SO C 24 h, 2 mm. 14.5%,, 1.62 g/cm 3, 61.8 mm 20 mm.,, 24 h.,, ( ) g/cm 3. GCTS. 500 kpa,, 8 h. 3.,,.,,., ( 5 d),,. 5 d. 40 d. 3 Table 3 Suction path 5 kpa 10 kpa 20 kpa 40 kpa 80 kpa 160 kpa 320 kpa 500 kpa % 20% 1.6 g/cm 3 9 ; 6% 22% 1.7 g/cm 3 9. LockLock,, 14d., 4. 3

5 254 20,.,,.,,. 4 Fig.4 Sketch of filter paper method. Leong [10],, Whatman 42 ( 5). 5, ( 1 MPa) ; ( ) ( ), 22%., [10], 22%,, s log s = w f (w f 47), (1) log s = w f (22 w f < 47), (2) log s = w f (w f < 22), (3), w f. 5 Whatman42 Fig.5 Calibration curves of Whatman No.42 filter paper 1.3.3, 14.5%,

6 2, : g/cm , 105 C ; 3 6.,.,, [11]. 60 d g/cm 3., ; kpa,,,,. 2.2 w ρ d 4. 7, 8. 6 ( ) Fig.6 Soil-water characteristic curves of Huai-an expansive soil (pressure plate method) 4 Table 4 Water content and dry density measured by filter paper method w/% ρ d /(g cm 3 ) w/% ρ d /(g cm 3 )

7 ,.,,. 7 ( ) Fig.7 SWCCs of Huai-an expansive soil (filter paper method) 8(a),,,,. 8 ( ) Fig.8 Comparison of SWCCs for different dry densities (filter paper method)

8 2, : 257,. ( 17% ),,,,. (10 MPa),, Romero [12]. 8(b),, ;,,, ;, ( ) 1.62 g/cm 3.,, ;,. 5 Table 5 Dry density of samples and corresponding suctions from vapor equilibrium method /MPa ρ d /(g cm 3 ) ρ d /(g cm 3 ) ρ d /(g cm 3 ) ρ d /(g cm 3 ) ,, ;, ;, 100 MPa,., ( ) ( ),, ;,,,,.,,., ( 5).,,,,.,.

9 ( ) Fig.9 SWCCs of Huai-an expansive soil (vapor equilibrium method ) kpa,,.,,. 10,,, 10(a). ( 10(b)), MPa, Fredlund [1] MPa,., 3, 3, ,, : (1), kpa.

10 2, : Fig.10 SWCCs of Huai-an expansive soil using three different test methods (2),, ;,. (3) 3, 100 MPa, ; 100 MPa,,. (4) MPa, MPa,. : [1] Fredlund D G, Xing A Q. Equations for the soil-water characteristic curve [J]. Canadian Geotechnical Journal, 1994, 31(4): [2] Fredlund D G. Engineering design protocols for unsaturated soils [C]// Proceeding of 3rd Asian Conference on Unsaturated Soils, Nanjing, 2007: [3] Fredlund D G, Rahardjo H. Soil mechanics for unsaturated soils [M]. John Wiley & Sons, [4],,. [J]., 2011, 36(6): [5],. [J]., 2011, 33(9):

11 [6],,. [J]., 2010, 31(1): [7]. [M]. :, [8],,,. - [J]., 2011, 32(4): [9]. OIML R121 [S] [10] Leong E C, He L, Rahardjo H. Factors affecting the filter paper method for total and matric suction measurements [J]. Geotechnical Testing Journal, 2002, 25(2): [11],, Tang A M,. [J]., 2011, 33(8): [12] Romero E, Vaunat J. Retention curves of deformable clays [C]// International Workshop on Experimental Evidence and Theoretical Approaches in Unsaturated Soils. 2000: :

THEORY. Water flow. Air flow

THEORY. Water flow. Air flow THEORY Water flow Air flow Does Suction Gradient Cause Flow? Coarse stone Fine ceramic Suction gradient to the right No suction gradient but still flow Does water content gradient cause Flow? Suction gradient