非饱和黄土结构性、吸力与抗剪强度特性的试验研究
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摘要
黄土是干旱半干旱地区特殊环境条件下沉积形成的,以粉粒为主,具有大孔隙,富含盐分,对水作用敏感的结构性土。黄土的结构性对黄土的工程性质影响很大,研究黄土的结构性对认清黄土的工程性质并用之解决实际问题有着重要的理论和实际意义。
本文在详细查阅了大量有关黄土结构性研究现状资料的基础上,通过西安南郊Q3黄土的非饱和三轴仪试验,测试分析了不同含水率非饱和黄土、饱和黄土及非饱和重塑黄土的应力应变变化规律及吸力特性变化规律。应用三轴应力条件下结构性土综合结构势的分析方法,首先分析了结构性参数随剪切变形的变化规律,表明在较低应变条件下土的结构性即发挥到了峰值,此后随着剪切变形发展,土的结构性逐渐衰减。与已有的研究成果具有一致的变化规律；其次比较分析了结构性参数变化与非饱和土基质吸力的变化,表明尽管结构性参数随剪切变形在不断衰减变化,但基质吸力在不断增长。进一步表明结构性是原状非饱和土的重要力学性质。再次从原状黄土、重塑黄土和饱和原状黄土的应力应变变化规律出发,比较分析了同一应变条件下由原状土与重塑土抗剪应力差反映的胶结作用和由重塑土与饱和原状土抗剪应力差反映的吸力作用,前者在结构性参数达到峰值时也发挥到了最大值,后者随剪切应变的增长而增大；最后进一步分析了结构性、抗剪强度和基质吸力之间的关系。原状土较重塑土的基质吸力小,但原状土较重塑土的抗剪强度大。非饱和原状黄土的应力应变曲线经结构性参数修正后,主应力差和结构性参数比与主应变的关系曲线呈线性变化规律,从而可以分析确定一定结构性参数条件下,原状土的抗剪强度变化特性。原状土与重塑土的结构性不同,其抗剪强度也不同。
从非饱和黄土的结构性参数、基质吸力、胶结作用、吸力作用的变化规律出发,揭示其结构性应力应变特性和抗剪强度特性机理,对于深化非饱和黄土力学特性具有重要价值。
The loess is one kind of structural soil, which is deposited under the special environmental condition in half arid and arid area. The loess consists of the silt primarily, containing the salinity and sensitive to water content. The structural characteristic of the loess has important influence on the physical, mechanical and engineering property of loess.
According to the related research of loess structural characteristics, tests of unsaturated Q3 intact and remolded loess having different water content has been done. Firstly, the article an analyzed the change rule of structural parameters along with the shearing deformation, indicated that the loess's structural property displayed the peak value in the low strain condition, after that along with the development of the shearing deformation, the loess's structural property weakens gradually. And it has the consistent change rule with the existing research results. Secondly, compared and analyzed the change of the constitutive parameter and the unsaturated soil's matric suction. Indicated that although the constitutive parameter and the shearing deformation is weakening and changing unceasingly, but the suction is growing unceasingly. Furthermore, indicated that the structural property is one of the important mechanical properties of the original unsaturated soil. Thirdly, from the stress-strain law of the original condition loess, the remolded loess and the saturated intact loess, the article compared and analyzed the cementation which reflected by the shear strain difference of the original condition loess and the remolded loess and the suction function which reflected by the shear strain difference of the saturated original loess and the remolded loess under the same strain condition. The former displayed the maximum value when the constitutive parameter achieves the peak value, although the latter shear's growth increased. In the end, further analyzed the relations between constitutive, the shearing strength and the matric suction. On the matric suction, the original condition loess is smaller than the remolded loess, but on the shear stain, the former is bigger. After the stress-strain curve of unsaturated loess modified by the structural parameters, the change rule of the ratio between the main stress difference and the structural parameters and the relations curve of the principal strain is linear, we can analysis and determine the shear strength characteristics of the original condition loess under the conditions of some structural parameters. If the structural of the intact loess and the remolded loess is different, their shear strength is also different.
From the change rule of its structural parameters, suction, cementation and the suction effect of the unsaturated loess, we can reveal its structural characteristics, the stress-strain relationship and shear strength characteristics. It has an important value to deep the mechanical properties of unsaturated loess.
本文在详细查阅了大量有关黄土结构性研究现状资料的基础上,通过西安南郊Q3黄土的非饱和三轴仪试验,测试分析了不同含水率非饱和黄土、饱和黄土及非饱和重塑黄土的应力应变变化规律及吸力特性变化规律。应用三轴应力条件下结构性土综合结构势的分析方法,首先分析了结构性参数随剪切变形的变化规律,表明在较低应变条件下土的结构性即发挥到了峰值,此后随着剪切变形发展,土的结构性逐渐衰减。与已有的研究成果具有一致的变化规律；其次比较分析了结构性参数变化与非饱和土基质吸力的变化,表明尽管结构性参数随剪切变形在不断衰减变化,但基质吸力在不断增长。进一步表明结构性是原状非饱和土的重要力学性质。再次从原状黄土、重塑黄土和饱和原状黄土的应力应变变化规律出发,比较分析了同一应变条件下由原状土与重塑土抗剪应力差反映的胶结作用和由重塑土与饱和原状土抗剪应力差反映的吸力作用,前者在结构性参数达到峰值时也发挥到了最大值,后者随剪切应变的增长而增大；最后进一步分析了结构性、抗剪强度和基质吸力之间的关系。原状土较重塑土的基质吸力小,但原状土较重塑土的抗剪强度大。非饱和原状黄土的应力应变曲线经结构性参数修正后,主应力差和结构性参数比与主应变的关系曲线呈线性变化规律,从而可以分析确定一定结构性参数条件下,原状土的抗剪强度变化特性。原状土与重塑土的结构性不同,其抗剪强度也不同。
从非饱和黄土的结构性参数、基质吸力、胶结作用、吸力作用的变化规律出发,揭示其结构性应力应变特性和抗剪强度特性机理,对于深化非饱和黄土力学特性具有重要价值。
The loess is one kind of structural soil, which is deposited under the special environmental condition in half arid and arid area. The loess consists of the silt primarily, containing the salinity and sensitive to water content. The structural characteristic of the loess has important influence on the physical, mechanical and engineering property of loess.
According to the related research of loess structural characteristics, tests of unsaturated Q3 intact and remolded loess having different water content has been done. Firstly, the article an analyzed the change rule of structural parameters along with the shearing deformation, indicated that the loess's structural property displayed the peak value in the low strain condition, after that along with the development of the shearing deformation, the loess's structural property weakens gradually. And it has the consistent change rule with the existing research results. Secondly, compared and analyzed the change of the constitutive parameter and the unsaturated soil's matric suction. Indicated that although the constitutive parameter and the shearing deformation is weakening and changing unceasingly, but the suction is growing unceasingly. Furthermore, indicated that the structural property is one of the important mechanical properties of the original unsaturated soil. Thirdly, from the stress-strain law of the original condition loess, the remolded loess and the saturated intact loess, the article compared and analyzed the cementation which reflected by the shear strain difference of the original condition loess and the remolded loess and the suction function which reflected by the shear strain difference of the saturated original loess and the remolded loess under the same strain condition. The former displayed the maximum value when the constitutive parameter achieves the peak value, although the latter shear's growth increased. In the end, further analyzed the relations between constitutive, the shearing strength and the matric suction. On the matric suction, the original condition loess is smaller than the remolded loess, but on the shear stain, the former is bigger. After the stress-strain curve of unsaturated loess modified by the structural parameters, the change rule of the ratio between the main stress difference and the structural parameters and the relations curve of the principal strain is linear, we can analysis and determine the shear strength characteristics of the original condition loess under the conditions of some structural parameters. If the structural of the intact loess and the remolded loess is different, their shear strength is also different.
From the change rule of its structural parameters, suction, cementation and the suction effect of the unsaturated loess, we can reveal its structural characteristics, the stress-strain relationship and shear strength characteristics. It has an important value to deep the mechanical properties of unsaturated loess.
引文
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[3]谢定义.试论我国黄土力学研究中的若干新趋向[J].岩土工程学报,2001,23(1)：3-13.
[4]邵生俊,龙吉勇,于清高,等.湿陷性黄土结构性变形特性分析[J].岩土力学,2006,27(10)：1668-1672.
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[21]陈铁林,李国英,沈珠江.结构性黏土的流变模型[J].水利水运学报,2003(2)：7-11.
[22]YU H S. CASM. A unified state parameter model for clay and sand[J]. International Journal of Numerical and Analytical Methods in Geomechanics,1998(22):621-653.
[23]DESAI C S. A consistent finite element technique for work-softening behavior[C] Proceedings of the International Conference on Computation Methods in Nolinear Mechanics,Austin,1974.
[24]骆亚生,谢定义,邵生俊,张爱军.复杂应力条件下的土结构性参数[J].岩石力学与工程学报,2004,23(24)：4248-4251.
[25]陈存礼,胡再强,高鹏.原状黄土的结构性及其与变形特性关系研究[J].岩土力学,2006,27(11)：1891-1896
[26]Butterfield. A natural compression law for soils[J].Geotechnique,1979,29,469-480.
[27]Dafalias Y F. Bounding surface plasticity. I. Mathematical foundation and hypoplasticity [J]. J Engng Mech,ASCE,1986,112:966-987.
[28]冯志焱.非饱和黄土结构性及有效应力动力等效粘弹性模型研究[博士毕业论文][D].西安：西安理工大学,2006.
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[31]陈存礼,高鹏,胡再强.黄土的增湿变形特性及其与结构性的关系[J].岩石力学与工程学报,2006,25(7)：1352-1360
[32]陈存礼,高鹏,何军芳.考虑结构性影响的原状黄土等效线性模型[J].岩土工程学报,2007,29(9)：1330-1336.
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[34]邵生俊,李彦兴,周飞飞.湿陷性黄土结构损伤演化特性[J].岩石力学与工程学报,2004,23(24)：4161-4165.
[35]邵生俊,龙吉勇,于清高,等.湿陷性黄土的结构性参数本构模型[J].水力学报,2006,39(11)：1315-1322.
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[2]邵生俊,周飞飞,龙吉勇.原状黄土结构性及其定量化参数研究[J].岩土工程学报,2004,26(4)：531-536.
[3]谢定义.试论我国黄土力学研究中的若干新趋向[J].岩土工程学报,2001,23(1)：3-13.
[4]邵生俊,龙吉勇,于清高,等.湿陷性黄土结构性变形特性分析[J].岩土力学,2006,27(10)：1668-1672.
[5]刘恩龙,沈珠江.结构性土的强度准则[J].岩土工程学报,2006,28(10)：1248-1252.
[6]苗天德,刘忠玉,任九生.湿陷性黄土的变形机理与本构关系[J].岩土工程学报,1999,21(4)：383-387.
[7]谢定义,齐吉琳,张振中.考虑土结构性的本构关系[J].土木工程学报,2000,33(4)：35-41.
[8]Leroueil S, Vaughan P R.The genegal and congruent effects of structure in natural soils and weak rocks [J]. Geotechnique,1990,40(3):467-488.
[9]BEEN K, JEFFERIES M G. A state parameter for sands[J].Geotechnique,1985(35):99-112.
[10]Lambe T W.A mechanical picture of shear strength in clay[C],Research conference on shear strength of cohesive soils,University of Colorado,Boulder,Colorado,1960:555-580.
[11]李宁军,夏永旭.基质吸力对非饱和黄土隧道力学特性影响研究[J].西安公路交通大学学报,2000,20(2)：49-51
[12]骆亚生.非饱和黄土在动、静复杂应力条件下的结构变化特性及结构性本构关系研究[D][博士学位论文].西安：西安理工大学,2003.
[13]太沙基(Terzaghi).理论土力学(中译本).中国地质出版社,1960.
[14]Skempton A W.Effective Stress in Soils,Concret and Rock,Pore Pressure and Suction.London:Butterworths,1960,4-16
[15]张诚厚.两种结构性粘土的土工性质.水利水运科学研究,1983(4)：65-71
[16]沈珠江.土体结构性的数学模型——21世纪土力学的核心问题[J].岩土工程学报,1996,18(1)：95～97
[17]苗天德.黄土湿陷变形机理的研究现状[C].中国工程建设标准化协会湿陷性黄土委员会全国黄土学术会议论文集,科学出版社,2001,73-82.
[18]张向东,荚颖,于崇,等.土结构性研究进展[C].第九届全国岩石力学与工程学术大会论文集,2006,63-96.
[19]王秋生.挠动土的结构性参数[J].岩土工程学报,2006,28(7)：914-917.
[20]党进谦,李靖.非饱和黄土的结构强度与抗剪强度.水利学报,2001(7)：79-90.
[21]陈铁林,李国英,沈珠江.结构性黏土的流变模型[J].水利水运学报,2003(2)：7-11.
[22]YU H S. CASM. A unified state parameter model for clay and sand[J]. International Journal of Numerical and Analytical Methods in Geomechanics,1998(22):621-653.
[23]DESAI C S. A consistent finite element technique for work-softening behavior[C] Proceedings of the International Conference on Computation Methods in Nolinear Mechanics,Austin,1974.
[24]骆亚生,谢定义,邵生俊,张爱军.复杂应力条件下的土结构性参数[J].岩石力学与工程学报,2004,23(24)：4248-4251.
[25]陈存礼,胡再强,高鹏.原状黄土的结构性及其与变形特性关系研究[J].岩土力学,2006,27(11)：1891-1896
[26]Butterfield. A natural compression law for soils[J].Geotechnique,1979,29,469-480.
[27]Dafalias Y F. Bounding surface plasticity. I. Mathematical foundation and hypoplasticity [J]. J Engng Mech,ASCE,1986,112:966-987.
[28]冯志焱.非饱和黄土结构性及有效应力动力等效粘弹性模型研究[博士毕业论文][D].西安：西安理工大学,2006.
[29]黄文熙.土的工程性质[M].北京：中国水利水电出版社,1983.
[30]谢定义,齐吉林,朱元琳.土的结构性参数及其与变形-强度的关系[J].水利学报,1999,(10)：1-6.
[31]陈存礼,高鹏,胡再强.黄土的增湿变形特性及其与结构性的关系[J].岩石力学与工程学报,2006,25(7)：1352-1360
[32]陈存礼,高鹏,何军芳.考虑结构性影响的原状黄土等效线性模型[J].岩土工程学报,2007,29(9)：1330-1336.
[33]骆亚生,胡仲有,张爱军.非饱和黄土结构性参数与其强度指标关系初探[J].第九届全国岩石力学与工程学术大会论文集,重庆大学出版社,2007：342-347.
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