斥水性砂土水-气形态及其对斥水-亲水转化的影响分析
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摘要
处于地球表面的土壤,尤其是耕作层土壤,受外界因素影响其接触角可能会发生改变。通过试验对不同接触角的壤质砂土中的孔隙水-气形态分布状况进行研究,试验结果表明:砂土颗粒与孔隙水间的接触角增大会使表层土壤中水封闭土层厚度减小,但接触角增大到一定值后,水封闭层的厚度不再发生变化。随着接触角的增大,气封闭层的厚度不断减小。与连续固体表面不同,砂土颗粒的接触角小于90°甚至降低至36°也会出现明显的斥水现象,但随着砂土中饱和度的增大,斥水现象会消失,砂土斥水与亲水转化时对应的饱和度与水封闭向双开敞转化时对应的饱和度基本一致,因此,砂土亲水与斥水转化时对应的临界含水率与孔隙水气分布形态密切相关,通过理想模型对两种不同水-气形态下土壤的基质吸力变化分析可以发现,产生这种现象是因为当土壤由水封闭变为双开敞时,水-气交界面在液体侧的曲率中心消失(接触角小于90°),气-液界面引起的基质吸力恒为"正"。
The earth surface soil,especially cultivated soil,contact angles of soil may be changed by external factors. Hydrophilic soil will translate into hydrophobic soil because of the bigger contact angle.Repellent soil will bring a series of agricultural and environmental problems. To develop the study to the pore water-air shape distribution in different contact angle soils,some tests were carried out. The experimental results showed that the increase of contact angles between soil particles and pore water can make the thickness of the closed-water soil layer reduced. When the contact angle was increased to a certain value,the closed-water soil layer thickness would remain unchanged. With the increase of the contact angle,the thickness of closed-air layer was reduced. It was different from the continuous solid surface,the contact angel of soil granule was less than 90°,even reduced to 36°,it would also appear the water-repellent phenomenon obviously,but with the increase of the saturation degree in the sand,the water-repellent phenomenon would disappear. The corresponding saturation of water repellent and hydrophilic conversion was basically consistent with the corresponding saturation of closed-water system and bi-opened system transformation. Therefore, the critical water content of hydrophilicity to hydrophobicity was closely related to pore water-air configurations. The matric suction in different pore water-air configurations was analyzed with ideal models, the causes of this phenomenon was the disappearance of water-air surface centers of curvature in water side( contact angle was less than 90°),the matric suction caused by water-air surface was greater than zero. The results suggested that it was not enough to focus on chemical property of soil water repellency,the mechanics of interface was also an important aspect of repellent soil study.
The earth surface soil,especially cultivated soil,contact angles of soil may be changed by external factors. Hydrophilic soil will translate into hydrophobic soil because of the bigger contact angle.Repellent soil will bring a series of agricultural and environmental problems. To develop the study to the pore water-air shape distribution in different contact angle soils,some tests were carried out. The experimental results showed that the increase of contact angles between soil particles and pore water can make the thickness of the closed-water soil layer reduced. When the contact angle was increased to a certain value,the closed-water soil layer thickness would remain unchanged. With the increase of the contact angle,the thickness of closed-air layer was reduced. It was different from the continuous solid surface,the contact angel of soil granule was less than 90°,even reduced to 36°,it would also appear the water-repellent phenomenon obviously,but with the increase of the saturation degree in the sand,the water-repellent phenomenon would disappear. The corresponding saturation of water repellent and hydrophilic conversion was basically consistent with the corresponding saturation of closed-water system and bi-opened system transformation. Therefore, the critical water content of hydrophilicity to hydrophobicity was closely related to pore water-air configurations. The matric suction in different pore water-air configurations was analyzed with ideal models, the causes of this phenomenon was the disappearance of water-air surface centers of curvature in water side( contact angle was less than 90°),the matric suction caused by water-air surface was greater than zero. The results suggested that it was not enough to focus on chemical property of soil water repellency,the mechanics of interface was also an important aspect of repellent soil study.
引文
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4巨娟丽,李毅,宋红阳,等.Ca Cl2溶液灌溉对土壤水盐与斥水性分布的影响[J/OL].农业机械学报,2014,45(10):159-166.http:∥www.j-csam.org/ch/reader/view_abstract.aspx?file_no=20141025&flag=1&journal_id=jcsam.DOI:10.6041/j.issn.1000-1298.2014.10.025.JU Juanli,LI Yi,SONG Hongyang,et al.Effects of Ca Cl2solution irrigation on distributions of soil water,salt and water repellency[J/OL].Transactions of the Chinese Society for Agricultural Machinery,2014,45(10):159-166.(in Chinese)
5 WOCHE S K,GOEBEL M O,KIKHAM M B,et al.Contact angle of soils as affected by depty,texture,and land management[J].European Journal of Soil Science,2005,56(2):239-251.
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7 VOGELMANN E S,REICHERT J M,PREVEDELL J,et al.Threshold water content beyond which hydrophobic soils become hydrophilic:the role of soil texture and organic matter content[J].Geoderma,2013,209-210:177-187.
8 BLACKWELL P S.Management of water repellency in Australia,and risks associated with preferential flow,pesticide concentration and leaching[J].Journal of Hydrology,2000,231-232(231):384-395.
9陈俊英,吴普特,张智韬,等.土壤斥水性对含水率的响应模型研究[J/OL].农业机械学报,2012,43(1):63-67.http:∥www.j-csam.org/ch/reader/view_abstract.aspx?file_no=20120113&flag=1&journal_id=jcsam.DOI:10.6041/j.issn.1000-1298.2012.01.013.CHEN Junying,WU Pute,ZHANG Zhitao,et al.Response models for soil water repellency and soil moisture[J/OL].Transactions of the Chinese Society for Agricultural Machinery,2012,43(1):63-67.(in Chinese)
10 TAUMER K,STOFFREGEN H,WESSOLET G.Determination of repellency distribution using soil organic matter and water content[J].Geoderma,2005,125(1-2):107-115.
11栾茂田,李顺群,杨庆.非饱和土的基质吸力和张力吸力[J].岩土工程学报,2006,28(7):863-868.LUAN Maotian,LI Shunqun,YANG Qing.Matric suction and tension suction of unsaturated soils[J].Chinese Journal of Geotechnical Engineering,2006,28(7):863-868.(in Chinese)
12张昭,刘奉银,张国平,等.不等径湿颗粒与液桥相互作用的微观水力特性[J].水利学报,2013,44(7):810-817.ZHANG Zhao,LIU Fengyin,ZHANG Guoping,et al.Microscopic hydraulic behavior from the interactions between uneven-sized wet particles and liquid bridge[J].Journal of Hydraulic Engineering,2013,44(7):810-817.(in Chinese)
13张昭,刘奉银,齐吉琳,等.粗颗粒间液桥毛细力演化规律的动态计算方法[J].岩土力学,2016,37(8):2263-2270.ZHANG Zhao,LIU Fengyin,QI Jilin,et al.A dynamic calculation method for evolution law of capillarity forces of liquid bridge between coarse particles[J].Rock and Soil Mechanics,2016,37(8):2263-2270.(in Chinese)
14杨松,吴珺华,董红艳,等.砂土和黏土的颗粒差异对土壤斥水性的影响[J].土壤学报,2016,53(2):421-426.YANG Song,WU Junhua,DONG Hongyan,et al.Effects of particle differences between sands and clay on soil water repellency[J].Acta Pedologica Sinica,2016,53(2):421-426.(in Chinese)
15 FREDLUND D G,XING A.Equations for the soil-water characteristic curve[J].Canadian Geotechnical Journal,1994,31(4):521-532.
16 RUSSELL A R,BUZZI O.A fractal basis for soil-water characteristics curves with hydraulic hysteresis[J].Géotechnique,2012,62(3):269-274.
17 CZACHOR H.Modelling the effect of pore structure and wetting angles on capillary rise in soils having different wettabilities[J].Journal of Hydrology,2006,328(328):604-613.
18 GUARRACINO L,ROTTING T,CARRERA J.A fractal model to describe the evolution of multiphase flow properties during mineral dissolution[J].Advances in Water Resources,2013,67(4):78-86.
19许兆义.包气带的水分分布特征及给水度的探讨[J].长春地质学院学报,1986(3):89-94.XU Zhaoyi.Feature of the moisture disturbution in aeration zone and specific yield[J].Journal of Changchun University of Earth Sciences,1986(3):89-94.(in Chinese)
20 SHIRTCLIFFE N J,MCHALE G,NEWTON M I,et al.Critical conditions for the wetting of soils[J].Applied Physics Letters,2006,89(9):094101.
21 LIKOS W J,LU N.Hysteresis of capillary stress in unsaturated granular soil[J].Journal of Engineering Mechanics,2004,130(6):646-655.
22 YANG S,LU T H.Study of soil-water characteristic curve using microscopic spherical particle model[J].Pedosphere,2012,22(1):103-111.
23 LEELAMANIE D A L,KARUBE J,YOSHIDA A.Clay effects on the contact angle and water drop penetration time of model soils[J].Soil Science&Plant Nutrition,2010,56(3):371-375.
24 MATAIX-SOLERA J,DOERR S H.Hydrophobicity and aggregate stability in calcareous topsoils from fire-affected pine forests in southeastern Spain[J].Geoderma,2004,118(1-2):77-88.
25 SPACCINI R,PICCOLO A,CONTE P,et al.Increased soil organic carbon sequestration through hydrophobic protection by humic substances.[J].Soil Biology&Biochemistry,2003,34(12):1839-1851.
26 LIKOS W J,LU N.Hysteresis of capillary stress in unsaturated granular soil[J].Journal of Engineering Mechanics,ASCE,2004,130(6):646-655.
2殷宗泽.土工原理[M].北京:中国水利水电出版社,2007.
3 CZACHOR H,DOERR S H,LICHNER L.Water retention of repellent and subcritical repellent soils:new insights from model and experimental investigations[J].Journal of Hydrology,2010,380(1):104-111.
4巨娟丽,李毅,宋红阳,等.Ca Cl2溶液灌溉对土壤水盐与斥水性分布的影响[J/OL].农业机械学报,2014,45(10):159-166.http:∥www.j-csam.org/ch/reader/view_abstract.aspx?file_no=20141025&flag=1&journal_id=jcsam.DOI:10.6041/j.issn.1000-1298.2014.10.025.JU Juanli,LI Yi,SONG Hongyang,et al.Effects of Ca Cl2solution irrigation on distributions of soil water,salt and water repellency[J/OL].Transactions of the Chinese Society for Agricultural Machinery,2014,45(10):159-166.(in Chinese)
5 WOCHE S K,GOEBEL M O,KIKHAM M B,et al.Contact angle of soils as affected by depty,texture,and land management[J].European Journal of Soil Science,2005,56(2):239-251.
6 REGALADO C M,RITTER A.Characterizing water dependent soil repellency with minimal parameter requirement[J].Soil Science Society of America,2005,69(6):1955-1966.
7 VOGELMANN E S,REICHERT J M,PREVEDELL J,et al.Threshold water content beyond which hydrophobic soils become hydrophilic:the role of soil texture and organic matter content[J].Geoderma,2013,209-210:177-187.
8 BLACKWELL P S.Management of water repellency in Australia,and risks associated with preferential flow,pesticide concentration and leaching[J].Journal of Hydrology,2000,231-232(231):384-395.
9陈俊英,吴普特,张智韬,等.土壤斥水性对含水率的响应模型研究[J/OL].农业机械学报,2012,43(1):63-67.http:∥www.j-csam.org/ch/reader/view_abstract.aspx?file_no=20120113&flag=1&journal_id=jcsam.DOI:10.6041/j.issn.1000-1298.2012.01.013.CHEN Junying,WU Pute,ZHANG Zhitao,et al.Response models for soil water repellency and soil moisture[J/OL].Transactions of the Chinese Society for Agricultural Machinery,2012,43(1):63-67.(in Chinese)
10 TAUMER K,STOFFREGEN H,WESSOLET G.Determination of repellency distribution using soil organic matter and water content[J].Geoderma,2005,125(1-2):107-115.
11栾茂田,李顺群,杨庆.非饱和土的基质吸力和张力吸力[J].岩土工程学报,2006,28(7):863-868.LUAN Maotian,LI Shunqun,YANG Qing.Matric suction and tension suction of unsaturated soils[J].Chinese Journal of Geotechnical Engineering,2006,28(7):863-868.(in Chinese)
12张昭,刘奉银,张国平,等.不等径湿颗粒与液桥相互作用的微观水力特性[J].水利学报,2013,44(7):810-817.ZHANG Zhao,LIU Fengyin,ZHANG Guoping,et al.Microscopic hydraulic behavior from the interactions between uneven-sized wet particles and liquid bridge[J].Journal of Hydraulic Engineering,2013,44(7):810-817.(in Chinese)
13张昭,刘奉银,齐吉琳,等.粗颗粒间液桥毛细力演化规律的动态计算方法[J].岩土力学,2016,37(8):2263-2270.ZHANG Zhao,LIU Fengyin,QI Jilin,et al.A dynamic calculation method for evolution law of capillarity forces of liquid bridge between coarse particles[J].Rock and Soil Mechanics,2016,37(8):2263-2270.(in Chinese)
14杨松,吴珺华,董红艳,等.砂土和黏土的颗粒差异对土壤斥水性的影响[J].土壤学报,2016,53(2):421-426.YANG Song,WU Junhua,DONG Hongyan,et al.Effects of particle differences between sands and clay on soil water repellency[J].Acta Pedologica Sinica,2016,53(2):421-426.(in Chinese)
15 FREDLUND D G,XING A.Equations for the soil-water characteristic curve[J].Canadian Geotechnical Journal,1994,31(4):521-532.
16 RUSSELL A R,BUZZI O.A fractal basis for soil-water characteristics curves with hydraulic hysteresis[J].Géotechnique,2012,62(3):269-274.
17 CZACHOR H.Modelling the effect of pore structure and wetting angles on capillary rise in soils having different wettabilities[J].Journal of Hydrology,2006,328(328):604-613.
18 GUARRACINO L,ROTTING T,CARRERA J.A fractal model to describe the evolution of multiphase flow properties during mineral dissolution[J].Advances in Water Resources,2013,67(4):78-86.
19许兆义.包气带的水分分布特征及给水度的探讨[J].长春地质学院学报,1986(3):89-94.XU Zhaoyi.Feature of the moisture disturbution in aeration zone and specific yield[J].Journal of Changchun University of Earth Sciences,1986(3):89-94.(in Chinese)
20 SHIRTCLIFFE N J,MCHALE G,NEWTON M I,et al.Critical conditions for the wetting of soils[J].Applied Physics Letters,2006,89(9):094101.
21 LIKOS W J,LU N.Hysteresis of capillary stress in unsaturated granular soil[J].Journal of Engineering Mechanics,2004,130(6):646-655.
22 YANG S,LU T H.Study of soil-water characteristic curve using microscopic spherical particle model[J].Pedosphere,2012,22(1):103-111.
23 LEELAMANIE D A L,KARUBE J,YOSHIDA A.Clay effects on the contact angle and water drop penetration time of model soils[J].Soil Science&Plant Nutrition,2010,56(3):371-375.
24 MATAIX-SOLERA J,DOERR S H.Hydrophobicity and aggregate stability in calcareous topsoils from fire-affected pine forests in southeastern Spain[J].Geoderma,2004,118(1-2):77-88.
25 SPACCINI R,PICCOLO A,CONTE P,et al.Increased soil organic carbon sequestration through hydrophobic protection by humic substances.[J].Soil Biology&Biochemistry,2003,34(12):1839-1851.
26 LIKOS W J,LU N.Hysteresis of capillary stress in unsaturated granular soil[J].Journal of Engineering Mechanics,ASCE,2004,130(6):646-655.