|
|
|
| EXPERIMENTAL RESEARCH ON GAS PERMEABILITY OF UNSATURATED Q3 LOESS |
| YAO Zhihua1，2，CHEN Zhenghan1，2，HUANG Xuefeng1，2，QIN Xiaohua1，2，ZHANG Junhao1，2 |
(1. Department of Architectural Engineering，Logistical Engineering University of PLA，Chongqing 401331，China；
2. Chongqing Key Laboratory of Geomechanics and Geoenvironmental Protection，Logistical Engineering University of PLA，Chongqing 401331，China) |
|
|
|
|
Abstract A series of tests considering influences of soil water content，dry density，and anisotropic property，were carried out to research the gas permeability coefficient of unsaturated undisturbed and remoulded Q3 loess，by using a modified triaxial gas permeable apparatus. The results show that，in a lower pressure condition，the results of gas permeability coefficient calculated by Darcy law and Fick law get close to each other；and in a higher pressure condition，the method obtained from Darcy law has an advantage over that got by Fick law. Gas flow of unsaturated undisturbed loess can be expressed by Darcy law. Gas permeability coefficient of unsaturated undisturbed loess decreases with the increase of water content and dry density；and this variation is more obvious in excess of optimum water content. Gas permeability coefficient of vertical undisturbed loess samples is greater than that of horizontal samples in the same buried depth because of anisotropic property. Comparing with gas permeability coefficient of undisturbed loess samples in case of same dry density，the influence of water content on that of remoulded loess is more significant. According to test data，formulas are proposed to compute gas permeability coefficient considering the influence of dry density，gas-filled porosity(saturation ratio) and anisotropic property. The computed results are in accordance with test data.
|
|
Received: 05 February 2012
|
|
|
|
| [1] RATTAN L. Encyclopedia of soil science[M]. 2nd ed. Florida，USA：CRC Press，2005：60.
[2] JUCA J F T，Maciel F J. Gas permeability of a compacted soil used in a landfill cover layer[J]. Geotechnical Special Publication，2006，147(2)：1 535–1 546.
[3] SANCHEZ-GIRON V，ANDREU E，HERNANZ J L. Response of five types of soil to simulated compaction in the form of confined uniaxial compression tests[J]. Soil and Tillage Research，1998，48(1/2)：37–50.
[4] MOLDRUP P，YOSHIKAWA S，OLESEN T，et al. Gas diffusivity in undisturbed volcanic ash soils：test of soil-water-characteristic based prediction models[J]. Soil Science Society of America Journal，2003，67(1)：41–51.
[5] SAMINGAN A S，LEONG E C，RAHARDJO H. A flexible wall permeameter for measurements of water and air coefficients of permeability of residual soils[J]. Canadian Geotechnical Journal，2003，40(3)：559–574.
[6] KAMIYA K，BAKRIE R，HONJO Y. A new method for the measurement of air permeability coefficient of unsaturated soil[J]. Geotechnical Special Publication，2006，147(2)：1 741–1 752.
[7] MOON S，NAM K，KIM J K，et al. Effectiveness of compacted soil liner as a gas barrier layer in the landfill final cover system[J]. Waste Management，2008，28(10)：1 909–1 914.
[8] 陈正汉，谢定义，王永胜. 非饱和土的水气运动规律及其工程性质研究[J]. 岩土工程学报，1993，15(3)：9–20.(CHEN Zhenghan，XIE Dingyi，WANG Yongsheng. Experimental studies of laws of fluid motion，suction and pore pressures in unsaturated soil[J]. Chinese
Journal of Geotechnical Engineering，1993，15(3)：9–20.(in Chinese))
[9] 王永胜，谢定义，郭庆国. 非饱和土中气体的运动特性与渗气系数的测定[J]. 西北水电，1993，(1)：43–49.(WANG Yongsheng，XIE Dingyi，GUO Qingguo. Laws of gas motion in unsaturated soil and determination of air permeability[J]. Northwest Water Power，1993，(1)：43–49.(in Chinese))
[10] 刘奉银，张 昭，周 冬. 湿度和密度双变化条件下的非饱和黄土渗气渗水函数[J]. 岩石力学与工程学报，2010，29(9)：1 907–1 914. (LIU Fengyin，ZHANG Zhao，ZHOU Dong. Density-saturation- dependent air-water permeability function of unsaturated loess[J]. Chinese Journal of Rock Mechanics and Engineering，2010，29(9)：1 907–1 914.(in Chinese))
[11] 姚志华，黄雪峰，陈正汉 等. 兰州地区大厚度自重湿陷性黄土场地浸水试验综合观测研究[J]. 岩土工程学报，2012，34(1)：65–74. (YAO Zhihua，HUANG Xuefeng，CHEN Zhenghan，et al. Comprehensive soaking test on self-weight collapse loess with heavy section in Lanzhou region[J]. Chinese Journal of Geotechnical Engineering，2012，34(1)：65–74.(in Chinese))
[12] HAMAMOTO S，MOLDRUP P，KAWAMOTO K，et al. Effect of particle size and soil compaction on gas transport parameters invariably-saturated sandy soils[J]. Vadose Zone Journal，2009，(8)：986–995.
[13] TULI A，HOPMANS J W，ROLSTON D E，et al. Comparison of air and water permeability between disturbed and undisturbed soils[J]. Soil Science Society of America Journal，2005，69(5)：1 361–1 371.
[14] 王卫华，王全九，樊 军. 原状土与扰动土导气率、导水率与含水率的关系[J]. 农业工程学报，2008，24(8)：25–29.(WANG Weihua，WANG Quanjiu，FAN Jun. Relationship between air permeability，water conductivity and water content for undisturbed and disturbed soils[J]. Transactions of the CSAE，2008，24(8)：25–29.(in Chinese))
[15] DELAGE P，CUI Y J，DE LAURE E. Air flow through an unsaturated compacted silt[C]// Proceedings of the 2nd International Conference on Unsaturated Soils. Beijing：[s.n.]，1998：563–568.
[16] 苗强强，陈正汉，张 磊，等. 非饱和黏土质砂的渗气规律试验研究[J]. 岩土力学，2010，31(12)：3 746–3 750.(MIAO Qiangqiang，CHEN Zhenghan，ZHANG Lei，et al. Experimental study of gas permeability of unsaturated clayey sand[J]. Rock and Soil Mechanics，2010，31(12)：3 746–3 750.(in Chinese))
[17] THAVEESAK V，ABDELMALEK B. Gas permeability of partially hydrated geosynthetic clay liners[J]. Journal of Geotechnical and Geoenvironmental Engineering，2004，130(1)：93–103.
[18] DEXTER A R. Soil physical quality：part III：unsaturated hydraulic conductivity and general conclusions about S-theory[J]. Geoderma，2004，120(3/4)：227–239. |
|
|
|
2012, Vol. 31 
