20 2 2014 4 JOURNAL OF SHANGHAI UNIVERSITY (NATURAL SCIENCE) Vol. 20 No. 2 Apr. 2014 DOI: 10.3969/j.issn.1007-2861.2013.07.007, (, 200072) :, 3,, 0 378 MPa.,,, 100 MPa, ;., 1 000 MPa.,,, ;,. : ; ; ; ; : TU 443 : A : 1007-2861(2014)02-0250-11 Soil-Water Characteristics of Huai-an Expensive Soil WU Yi-gao, SUN De-an (Department of Civil Engineering, Shanghai University, Shanghai 200072, 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 1 000 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). ( ), : 2013-03-18 : (11272194) : (1962 ),,,,. E-mail: sundean@shu.edu.cn
2, : 251 4 4 4,. 92 km,.,,..,.,,,,,,.,. [1].,. Fredlund [2], -.,.,, 1.5 MPa [3]..,,. [4], ; [5], ; [6],,.,.,,. 1 1.1, 2 m, 1. [7],. 1 Table 1 Physical indexes of Huai-an expensive soil G s 2.74 w/% 22.2 26.9 ρ/(g cm 3 ) 1.89 1.96 <0.005 mm/% 20.60 w L/% 49.88 w P/% 23.04 I P 26.84 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). ã Øå e c ^u=pøå, ~ >è ÚüY+ YÞ, ±B* üyyþ, äáå IJï. È { ^ Ü ) Whatman 42 ÒÈ!LockLock Ý! Ý 0.000 1 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
2, : 253 ( 3). RH(%) [9],, 9 ( 2). 2 (20 C) Table 2 Saturated salt solution, RH and corresponding suction (20 C) RH/% /MPa LiBr 6.6 367.54 LiCl H 2O 12.0 286.70 CH 3COOK 23.1 198.14 MgCl 2 6H 2O 33.1 149.51 K 2CO 3 43.2 113.50 KI 69.9 48.42 NaCl 75.5 38.00 KCl 85.1 21.82 K 2SO 4 97.6 3.29 1.3 1.3.1 105 C 24 h, 2 mm. 14.5%,, 1.62 g/cm 3, 61.8 mm 20 mm.,, 24 h.,, ( ). 1.56 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 1.3.2. 4% 20% 1.6 g/cm 3 9 ; 6% 22% 1.7 g/cm 3 9. LockLock,, 14d., 4. 3
254 20,.,,.,,. 4 Fig.4 Sketch of filter paper method. Leong [10],, Whatman 42 ( 5). 5, ( 1 MPa) ; ( ) ( ), 22%., [10], 22%,, s log s = 2.909 0.029 9w f (w f 47), (1) log s = 4.945 0.067 3w f (22 w f < 47), (2) log s = 5.31 0.087 9w f (w f < 22), (3), w f. 5 Whatman42 Fig.5 Calibration curves of Whatman No.42 filter paper 1.3.3, 14.5%,
2, : 255 1.62 g/cm 3. 3 6, 105 C ; 3 6.,.,, [11]. 60 d. 2 2.1 6 1.56 g/cm 3., ; 100 200 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 ) 4.19 1.580 5.81 1.708 5.89 1.600 7.48 1.676 7.72 1.610 9.70 1.684 9.57 1.615 10.96 1.701 11.64 1.615 12.87 1.739 14.05 1.614 14.85 1.757 15.80 1.620 16.62 1.754 17.88 1.619 18.99 1.718 20.46 1.604 22.57 1.689
256 20 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)
2, : 257,. ( 17% ),,,,. (10 MPa),, Romero [12]. 8(b),, ;,,, ;,. 2.3 5 ( ) 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 ) 1.919 1.773 367.54 1.528 1.919 1.869 1.763 286.7 1.910 1.755 198.14 1.879 1.744 149.51 1.513 1.827 1.807 1.715 113.5 1.815 1.641 48.42 1.805 1.617 38 1.511 1.801 1.790 1.603 21.82 1.786 1.582 3.29 9.,, ;, ;, 100 MPa,., ( ) ( ),, ;,,,,.,,., ( 5).,,,,.,.
258 20 9 ( ) Fig.9 SWCCs of Huai-an expansive soil (vapor equilibrium method ) 2.4 3 10 3. 500 kpa,,.,,. 10,,, 10(a). ( 10(b)), 1 000 MPa, Fredlund [1] 1 000 MPa,., 3, 3, 3. 3 3,, : (1), 3. 100 200 kpa.
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