风化花岗岩土的持水特性研究
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摘要
以不同风化程度的花岗岩双层土质边坡土体为研究对象,利用压力板法和饱和盐溶液蒸汽平衡法,研究了在全吸力范围内压实样的持水特性。实验结果表明,全风化土的进气值和残余吸力值均低于残积土的,且过渡区呈线性有较大的坡度。花岗岩风化程度差异产生不同的风化产物,影响土体的矿物成分与孔隙结构进而控制土体的持水特性。通过X-射线衍射实验分析土样的黏土矿物成分,采用硅酸盐化学全分析土体的化学成分和风化成矿情况,研究矿物成分对土体持水特性的影响;最后通过扫描电镜与压汞实验,验证分析孔隙结构与分布对持水特性的影响。
By using the pressure plate technique and the vapor equilibrium method with saturated salt solution, the water-holding characteristics of a granite double-layer soil slope with different weathering degrees are studied. The experimental results show that the inlet value and residual suction value of fully weathered soils are lower than that of residual soils, and the transition zone has a higher slope. The weathering degree of granite has different weathering products, which influences the mineral composition and pore structure of the soils, and then controls the water-holding characteristics of the soil body. The clay mineral compositions of soil samples are analyzed by means of the X-ray diffraction experiment, and the silicate chemical analysis is used to understand the chemical composition and weathering mineralization of soils. The influences of mineral composition on the water-holding characteristics of soils are studied. Finally, the influences of pore structure and distribution on the water-holding characteristics are verified by the SEM and mercury intrusion experiments.
By using the pressure plate technique and the vapor equilibrium method with saturated salt solution, the water-holding characteristics of a granite double-layer soil slope with different weathering degrees are studied. The experimental results show that the inlet value and residual suction value of fully weathered soils are lower than that of residual soils, and the transition zone has a higher slope. The weathering degree of granite has different weathering products, which influences the mineral composition and pore structure of the soils, and then controls the water-holding characteristics of the soil body. The clay mineral compositions of soil samples are analyzed by means of the X-ray diffraction experiment, and the silicate chemical analysis is used to understand the chemical composition and weathering mineralization of soils. The influences of mineral composition on the water-holding characteristics of soils are studied. Finally, the influences of pore structure and distribution on the water-holding characteristics are verified by the SEM and mercury intrusion experiments.
引文
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[3]NG C W W,PANG Y W.Experimental investigations of the soil-water characteristics of a volcanic soil[J].Canadian Geotechnical Journal,2000,37(6):1252-1254.
[4]陈正汉.非饱和土与特殊土力学的基本理论研究[J].岩土工程学报,2014,36(2):201-272.(CHEN Zheng-han.On basic theories of unsaturated soils and special soils[J].Chinese Journal of Geotechnical Engineering,2014,36(2):201-272.(in Chinese))
[5]SALAGER S,ALESSIO M,FERRARI A,et al.Investigation into water retention behavior of deformable soils[J].Canadian Geotechnical Journal,2013,50(2):200-208.
[6]GB50021-2001岩土工程勘察规范[S].2009.(GB50021-2001 Geotechnical engineering specification[S].2009.(in Chinese))
[7]GAO Y,SUN D A,ZHOU A.N Hydro-mechanical behaviour of unsaturated soil with different specimen preparations[J].Canadian Geotechnical Journal,2015,53(6).
[8]文宝萍,胡艳青.颗粒级配对非饱和黏性土基质吸力的影响规律[J].水文地质工程地质,2008,35(6):50-55.(WENBao-ping,HU Yan-qing.Effect of particle size distribution on the metric suction of unsaturated clayey soils[J].Hydrogeology&Engineering Geology,2008,35(6):50-55.(in Chinese))
[9]FREDLUND D G,RAHARDJO H.Soil mechanics for unsaturated soils[M].New York:John Wiley&Sons,Inc,1993.
[10]PETERSEN L W,MOLDRUP P,JACOBSEN O H,et al.Relations between specific area and soil physical and chemical properties[J].Soil Science,1996,161(1):9-21.
[11]MADSEN H B,JENSEN C R,BOYSEN T.A comparison of the thermocouple psychrometer and the pressure plate methods for determination of soil water characteristic curves[J].Journal of Soil Science,1986,37(3):357-362.
[12]TULLER M,OR D.Water films and scaling of soil characteristic curves at low water contents[J].Water Resources Research,2005,41(9):W09403 1-6.
[13]LU N,KHORSHIDI M.Mechanisms for soil-water retention and hysteresis at high suction range[J].Journal of Geotechnical&Geoenvironmental Engineering,2015,141(8):04015032.
[14]谭罗荣,孔令伟.某类红黏土的基本特性与微观结构模型[J].岩土工程学报,2001,23(4):458-262.(TAN Luo-rong,KONG Ling-wei.Fundamental property and microstructure model of red clay[J].Chinese Journal of Geotechnical Engineering,2001,23(4):458-262.(in Chinese)).
[15]KODIKARA J,BARBOUR S L,FREDLUND D G.Change in clay structure behaviour due to wetting and drying[C]//Proceedings of 8th Australian-Zealand Conference on Geomechanics.Hobart,1999:179-185.
[16]VANAPALLI S K,FREDLUND D G,PUFAHL D E.The influence of soil structure and stress history on the soil-water characteristics of a compacted till[J].Géotechnique,1999,49(2):143-159.