控制厚度条件下土体干缩开裂的界面摩擦效应
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摘要
土体厚度和界面粗糙度对土体干缩开裂有着重要影响,为了探究土体在不同厚度和界面粗糙度条件下的干缩开裂特性,开展了一系列室内干燥试验。试验中共配置了9组初始饱和的泥浆样,分别设置3种不同的土体厚度和3种不同的界面粗糙度,并在恒温30℃的条件下进行干燥,实时记录试样含水率变化及表面裂隙的演化过程,利用数字图像处理技术,对裂隙网络进行了定量分析,得到不同厚度和不同界面粗糙度条件下土体龟裂的动态发展过程及相关参数。试验结果表明:①界面粗糙度越大,龟裂发育速度越快,然而土体厚度越大,龟裂发育速度越慢,且土体整体收缩效应越明显;②界面粗糙度越大,龟裂发育程度越高,然而增加土体厚度可以削弱界面粗糙度对龟裂发育过程的影响;③土体厚度和界面粗糙度都对土体开裂时的临界含水率有重要影响,且两者对龟裂发育过程的影响具有耦合作用关系。最后,结合土体干燥收缩特性,探讨了上述两种因素对龟裂的影响机理。
As the layer thickness and interfacial roughness of soils are the most important factors affecting their desiccation cracking, a series of desiccation tests are therefore conducted to investigate the shrinkage and cracking characteristics under various soil thicknesses and interfacial roughnesses. In the tests, nine slurry specimens of initial saturation are prepared and dried under a constant temperature of 30℃ and three different soil layer thicknesses and interfacial roughnesses. The change of water content and surface cracking are kept in a real-time record during the whole process of drying. The image processing technique is employed for quantitative analysis of crack network. The dynamic desiccation cracking process is recorded and the relative parameters are obtained under different soil layer thicknesses and interfacial roughnesses. The results show that:(1)The larger the interfacial roughness, the faster the rate of cracking development, while the greater the thickness of soil layer, the slower the rate of cracking development, and the more significant the effects of integrated shrinkage of soils;(2) The larger the interfacial roughness, the higher the degree of cracking development. However, the increase of soil thickness can restrain the influences of interfacial roughness on cracking development;(3) The influences of interfacial roughness and soil layer thickness on cracking have certain influences on the average water content during the initial cracking of soils. Additionally, the influences of the two factors on cracking development have coupling relationship. Finally, the influence mechanism of the two factors is explored by expatiating the mechanism of soil shrinkage.
As the layer thickness and interfacial roughness of soils are the most important factors affecting their desiccation cracking, a series of desiccation tests are therefore conducted to investigate the shrinkage and cracking characteristics under various soil thicknesses and interfacial roughnesses. In the tests, nine slurry specimens of initial saturation are prepared and dried under a constant temperature of 30℃ and three different soil layer thicknesses and interfacial roughnesses. The change of water content and surface cracking are kept in a real-time record during the whole process of drying. The image processing technique is employed for quantitative analysis of crack network. The dynamic desiccation cracking process is recorded and the relative parameters are obtained under different soil layer thicknesses and interfacial roughnesses. The results show that:(1)The larger the interfacial roughness, the faster the rate of cracking development, while the greater the thickness of soil layer, the slower the rate of cracking development, and the more significant the effects of integrated shrinkage of soils;(2) The larger the interfacial roughness, the higher the degree of cracking development. However, the increase of soil thickness can restrain the influences of interfacial roughness on cracking development;(3) The influences of interfacial roughness and soil layer thickness on cracking have certain influences on the average water content during the initial cracking of soils. Additionally, the influences of the two factors on cracking development have coupling relationship. Finally, the influence mechanism of the two factors is explored by expatiating the mechanism of soil shrinkage.
引文
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[16]TANG Chao-sheng.Experimental investigation on evaporation process of water in soil during drying[J].Journal of Engineering Geology,2011.
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[21]唐朝生,施斌,顾凯.土中水分的蒸发过程试验研究[J].工程地质学报,2011,19(6):875-881.(TANGChao-sheng,SHI Bin,GU Kai.Experimental investigation on evaporation process of water in soil during drying[J].Journal of Engineering Geology,2011,19(6):875-881.(in Chinese))
[22]TANG Chao-sheng,SHI Bin,LIU Chun,et al.Experimental characterization of shrinkage and desiccation cracking in thin clay layer[J].Applied Clay Science,2011,52(1/2):69-77.
[23]FREDLUND D G,RAHARDJO H.Soil mechanics for unsaturated soils[M].New York:Wiley,1993.
[24]BRONSWIJK J J B.Modeling of water balance,cracking and subsidence of clay soils[J].Journal of Hydrology,1988,97(3):199-212.
[25]唐朝生,施斌,刘春.膨胀土收缩开裂特性研究[J].工程地质学报,2012,20(5):663-673.(TANG Chao-sheng,SHI Bin,LIU Chun.Study on desiccation cracking behaviour of expansive soil[J].Journal of Engineering Geology,2012,20(5):663-673.(in Chinese))
[26]HILLEL D.Introduction to soil physics[J].Introduction to Soil Physics,2011:321-357.
[27]GROISMAN A,KAPLAN E.An experimental study of cracking induced by desiccation[J].Epl,2007,25(6):415.
[2]PERON H,HUECKEL T,LALOUI L,et al.Fundamentals of desiccation cracking of fine-grained soils:experimental characterisation and mechanisms identification[J].Canadian Geotechnical Journal,2009,46(10):1177-1201.
[3]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))
[4]MSORRIS P H,GRAHAM J,WILLIAMS D J.Cracking in drying soils[J].Canadian Geotechnical Journal,1992,29(2):263-277.
[5]袁俊平,殷宗泽.膨胀土裂隙的量化指标与强度性质研究[J].水利学报,2004,35(6):108-113.(YUAN Jun-ping,YIN Zong-ze.Quantitative index of fissure and strength characteristics of fissured expansive soils[J].Journal of Hydraulic Engineering,2004,35(6):108-113.(in Chinese))
[6]孔令伟,陈建斌,郭爱国,等.大气作用下膨胀土边坡的现场响应试验研究[J].岩土工程学报,2007,29(7):1065-1073.(KONG Ling-wei,CHEN Jian-bin,GUO Ai-guo,et al.Field response tests on expansive soil slopes under atmosphere[J].Chinese Journal of Geotechnical Engineering,2007,29(7):1065-1073.(in Chinese))
[7]MILLER C J,HONG M,YESILLER N.Experimental analysis of desiccation crack propagation in clay liners[J].Journal of the American Water Resources Association,1998,34(3):677-686.
[8]MILLER C J.Field investigation of clay liner movement[J].Hazardous Waste&Hazardous Materials,1988,5(3):231-238.
[9]STOLTE J,RITSEMA C J,Roo A P J D.Effects of crust and cracks on simulated catchment discharge and soil loss[J].Journal of Hydrology,1997,195(1/2/3/4):279-290.
[10]TOWNER G D.The mechanics of cracking of drying clay[J].Journal of Agricultural Engineering Research,1987,36(2):115-124.
[11]LAKSHMIKANTHAM R,PRATPERE C,LEDESMAALBERTO.Experimental evidence of size effect in soil cracking[J].Canadian Geotechnical Journal,2008,49(3):264-284.
[12]MITCHELL J K,SOGA K,MITCHELL J K,et al.Fundamentals of soil behavior[M].New York:Wiley,1976.
[13]TOLLENAAR R N,PAASSEN L A V,JOMMI C.Observations on the Desiccation and Cracking of Clay Layers[J].Engineering Geology,2017.
[14]TANG Chao-Sheng,SHI Bin,LIU Chun,et al.Influencing factors of geometrical structure of surface shrinkage cracks in clayey soils[J].Engineering Geology,2008,101(3/4):204-217.
[15]TANG Chao-sheng,CUI Yu-jun,TANG A M,et al.Experiment evidence on the temperature dependence of desiccation cracking behavior of clayey soils[J].Engineering Geology,2010,114(3/4):261-266.
[16]TANG Chao-sheng.Experimental investigation on evaporation process of water in soil during drying[J].Journal of Engineering Geology,2011.
[17]LIU Chun,TANG Chao-Sheng,SHI Bin,et al.Automatic quantification of crack patterns by image processing[J].Computers&Geosciences,2013,57(4):77-80.
[18]WANG Jun-jie,ZHU Jun-gao,CHIU C F,et al.Experimental study on fracture toughness and tensile strength of a clay[J].Engineering Geology,2007,94(1):65-75.
[19]易顺民,黎志恒.膨胀土裂隙结构的分形特征及其意义[J].岩土工程学报,1999,21(3):294-298.(YI Shun-min,LIZhi-heng.The fractal characteristics of fractures in expansion soil and its significance[J].Chinese Journal of Geotechnical Engineering,1999,21(3):294-298.(in Chinese))
[20]唐朝生,王德银,施斌,等.土体干缩裂隙网络定量分析[J].岩土工程学报,2013,35(12):2298-2305.(TANGChao-sheng,WANG De-yin,SHI Bin,et al.Quantitative analysis of soil desiccation crack network[J].Chinese Journal of Geotechnical Engineering,2013,35(12):2298-2305.(in Chinese))
[21]唐朝生,施斌,顾凯.土中水分的蒸发过程试验研究[J].工程地质学报,2011,19(6):875-881.(TANGChao-sheng,SHI Bin,GU Kai.Experimental investigation on evaporation process of water in soil during drying[J].Journal of Engineering Geology,2011,19(6):875-881.(in Chinese))
[22]TANG Chao-sheng,SHI Bin,LIU Chun,et al.Experimental characterization of shrinkage and desiccation cracking in thin clay layer[J].Applied Clay Science,2011,52(1/2):69-77.
[23]FREDLUND D G,RAHARDJO H.Soil mechanics for unsaturated soils[M].New York:Wiley,1993.
[24]BRONSWIJK J J B.Modeling of water balance,cracking and subsidence of clay soils[J].Journal of Hydrology,1988,97(3):199-212.
[25]唐朝生,施斌,刘春.膨胀土收缩开裂特性研究[J].工程地质学报,2012,20(5):663-673.(TANG Chao-sheng,SHI Bin,LIU Chun.Study on desiccation cracking behaviour of expansive soil[J].Journal of Engineering Geology,2012,20(5):663-673.(in Chinese))
[26]HILLEL D.Introduction to soil physics[J].Introduction to Soil Physics,2011:321-357.
[27]GROISMAN A,KAPLAN E.An experimental study of cracking induced by desiccation[J].Epl,2007,25(6):415.