压实黄土平面应变方向的主应力特性
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摘要
对不同含水率压实黄土进行等小主动主应力σ_x的平面应变三轴试验,研究了含水率w及小主动主应力σ_x对加载过程中平面应变方向主应力σ_y特性的影响,根据试验结果提出了描述平面应变方向与其它方向主应力双线性关系的表达式,验证了基于典型强度准则的中主应力公式描述压实黄土σ_y变化的适用性。研究结果表明:在等向固结及初始加载阶段,平面应变方向主应力不是中主应力σ_2,而是小主应力σ_3;平面应变方向主应力比σ_y/σ_x随着主动主应力比R的增大先平缓后快速增大,转折点前后主应力之间分别呈线性和非线性关系;转折点处的主动主应力比Rz大于平面应变方向主应力由小主应力转变为中主应力临界点处的主动主应力比Rc,w及σ_x对Rz的影响较大,对Rc的影响很小。R较小时,w及σ_x对加载过程中σ_y/σ_x几乎没有影响。主应力参数K(=2σ_y/(σ_x+σ_z))与主动主应力比R之间呈双直线;前段为水平直线,K近似为常数Kc;后段为倾斜向上的直线;Kc及直线斜率m与w及σ_x的大小无关。提出的双线性函数能较好地预测压实黄土加载过程中σ_y的变化特性,而仅在土样破坏时,基于Lade-Duncan及SMP准则的中主应力公式的预测值与试验值比较接近。
The plane strain triaxial tests in which the minor active principal stress(also called σ_x) keeps invariable are performed on the compacted loess with different water contents. The influences of σ_x and water content(also called w) on characteristics of the principal stress in plane strain direction(also called σ_y) during loading are studied. Based on the test results, the expressions describing the bilinear relationships between the principal stress in the plane strain direction and that in other directions are proposed. It is verified whether or not σ_y can be predicted by the expressions for the intermediate principal stress based on different strength criteria for compacted loess. The test results show that σ_y is not the intermediate principal stress(also called σ_2) but the minor principal stress(also called σ_3) during the isotropic consolidation and the initial loading stage. The ratio of the principal stress in the plane strain direction to the minor active principal stress(also called σ_y/σ_x) fast increases after the gentle development stage with the increase of the ratio of the major active principal stress to the minor one(also called R), and the relationships between the principal stresses are respectively linear and nonlinear before and after the turning point. The ratio of the major active principal stress to the minor one at the turning point(also called Rz) is larger than that at the critical point where σ_y transforms σ_2 to σ_3(also called Rc). w and σ_x have obvious influences on Rz but little ones on Rc. The effects of w and σ_x on σ_y/σ_x are little as R is small. The relationships between the principal stress parameter(=2σ_y/(σ_x+σ_z), also called K) and R can be describedas two-stage lines. The one is horizontal and K is constant Kc in the first stage. The other one is inclined upward in the second stage. The slope m and Kc are irrelevant to w and σ_x. The change of σ_y during the loading can be better predicted by the proposed bilinear function. The predictedresults are approximately equal to the test ones only at the failure of soil samples, using the expressions for the intermediateprincipal stress based on the Lade-Duncan and the SMP strength criteria.
The plane strain triaxial tests in which the minor active principal stress(also called σ_x) keeps invariable are performed on the compacted loess with different water contents. The influences of σ_x and water content(also called w) on characteristics of the principal stress in plane strain direction(also called σ_y) during loading are studied. Based on the test results, the expressions describing the bilinear relationships between the principal stress in the plane strain direction and that in other directions are proposed. It is verified whether or not σ_y can be predicted by the expressions for the intermediate principal stress based on different strength criteria for compacted loess. The test results show that σ_y is not the intermediate principal stress(also called σ_2) but the minor principal stress(also called σ_3) during the isotropic consolidation and the initial loading stage. The ratio of the principal stress in the plane strain direction to the minor active principal stress(also called σ_y/σ_x) fast increases after the gentle development stage with the increase of the ratio of the major active principal stress to the minor one(also called R), and the relationships between the principal stresses are respectively linear and nonlinear before and after the turning point. The ratio of the major active principal stress to the minor one at the turning point(also called Rz) is larger than that at the critical point where σ_y transforms σ_2 to σ_3(also called Rc). w and σ_x have obvious influences on Rz but little ones on Rc. The effects of w and σ_x on σ_y/σ_x are little as R is small. The relationships between the principal stress parameter(=2σ_y/(σ_x+σ_z), also called K) and R can be describedas two-stage lines. The one is horizontal and K is constant Kc in the first stage. The other one is inclined upward in the second stage. The slope m and Kc are irrelevant to w and σ_x. The change of σ_y during the loading can be better predicted by the proposed bilinear function. The predictedresults are approximately equal to the test ones only at the failure of soil samples, using the expressions for the intermediateprincipal stress based on the Lade-Duncan and the SMP strength criteria.
引文
[1]殷宗泽,赵航.中主应力对土体本构关系的影响[J].河海大学学报,1990,18(5):54-61.(YIN Zong-ze,ZHAOHang.Effect of middle principal stress on constitutive relationship[J].Journal of Hohai University,1990,18(5):54-61.(in Chinese))
[2]施维成,朱俊高,张博,等.粗粒土在平面应变条件下的强度特性研究[J].岩土工程学报,2011,33(12):1974-1979.(SHI Wei-cheng,ZHU Jun-gao,ZHANG Bo,et al.Strength characteristics of coarse-grained soil under plane strain condition[J].Chinese Journal of Geotechnical Engineering,2011,33(12):1974-1979.(in Chinese))
[3]GEORGIADIS K,POTTS D M,ZDRAVKOVIC L.Modelling the shear strength of soils in the general stress space[J].Computers and Geotechnics,2004,31:357-364.
[4]SATAKE M.Stress-deformation and strength characteristics of soil under three difference principal stresses[J].Proceedings of Japan Society of Civil Engineering,1976,246:137-138.
[5]罗汀,姚仰平,松岡元.基于SMP准则的土的平面应变强度公式[J].岩土力学,2000,21(4):390-393.(LUO Ting,YAO Yang-ping,MATSUOKA H.Soil strength equation in plane strain based on SMP[J].Rock and Soil Mechanics,2000,21(4):390-393.(in Chinese))
[6]李刚,谢云,陈正汉.平面应变状态下黏性土破坏时的主应力公式[J].岩石力学与工程学报,2004,23(18):3174-3177.(LI Gang,XIE Yun,CHEN Zheng-han.Formula of intermediate principal stress at failure for coherent soil inplane strain state[J].Chinese Journal of Rock Mechanicsand Enginerring,2004,23(18):3174-3177.(in Chinese))
[7]LEE K L.Comparison of plane strain and triaxial tests on sand[J].ASCE Journal of Soil Mechanics and Foundation Division,1970,96(SM3):901-923.
[8]YU M H,HE L N.A new model and theory on yield and failure of materials under the complex stress state[M]//Mechanical behavior of materials-VI.Oxford:Pergamon Press,1991:841-846.
[9]李广信,黄永男,张其光.土体平面应变方向上的主应力[J].岩土工程学报,2001,23(3):358-361.(LI Guang-xin,HUANG Yong-nan,ZHANG Qi-guang.The principal stress of soil in the direction of plane strain[J].Chinese Journal of Geotechnical Engineering,2001,23(3):358-361.(in Chinese))
[10]李广信,张其光,黄永男.等应力比平面应变试验中主应力转换的研究[J].岩土力学,2006,27(11):1867-1872.(LI Guang-xin,ZHANG Qi-guang,HUANG Yong-nan.Study on transforming of principal stresses in constant stress ration plane strain tests[J].Rock and Soil Mechanics,2006,27(11):1867-1872.(in Chinese))
[11]曹泽民.结构性对重塑黄土变形强度特性的影响[D].西安:西安理工大学,2013:56-65.(CAO Ze-min.The influence of structure on deformation and strength of remolded loess[D].Xi'an:Xi'an University of Technology,2013:56-65.(in Chinese))
[12]张玉,邵生俊.平面应变条件下黄土的竖向加载变形与强度特性分析[J].土木工程学报,2016,49(3):112-121.(An analysis of vertical loading deformation and strength characteristics of loess under plain strain condition[J].China Civil Engineering Journal,2016,49(3):112-121.(in Chinese))
[13]路德春,姚仰平,周安楠.土体平面应变条件下的主应力关系[J].岩石力学与工程学报,2006,25(11):2320-2326.(LU De-chun,YAO Yang-ping,ZHOU An-nan.Relationship between principal stresses of soil mass under plane strain condition[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(11):2320-2326.(in Chinese))
[14]俞茂宏,杨松岩,刘春阳,等.统一平面应变滑移线场理论[J].土木土程学报,1997,30(2):14-26,41.(YUMao-hong,YANG Song-yan,LIU Chun-yang,et al.Unified plane-strain slip line field theory system[J].China Civil Engineering Journal,1997,30(2):14-26,41.(in Chinese))
[2]施维成,朱俊高,张博,等.粗粒土在平面应变条件下的强度特性研究[J].岩土工程学报,2011,33(12):1974-1979.(SHI Wei-cheng,ZHU Jun-gao,ZHANG Bo,et al.Strength characteristics of coarse-grained soil under plane strain condition[J].Chinese Journal of Geotechnical Engineering,2011,33(12):1974-1979.(in Chinese))
[3]GEORGIADIS K,POTTS D M,ZDRAVKOVIC L.Modelling the shear strength of soils in the general stress space[J].Computers and Geotechnics,2004,31:357-364.
[4]SATAKE M.Stress-deformation and strength characteristics of soil under three difference principal stresses[J].Proceedings of Japan Society of Civil Engineering,1976,246:137-138.
[5]罗汀,姚仰平,松岡元.基于SMP准则的土的平面应变强度公式[J].岩土力学,2000,21(4):390-393.(LUO Ting,YAO Yang-ping,MATSUOKA H.Soil strength equation in plane strain based on SMP[J].Rock and Soil Mechanics,2000,21(4):390-393.(in Chinese))
[6]李刚,谢云,陈正汉.平面应变状态下黏性土破坏时的主应力公式[J].岩石力学与工程学报,2004,23(18):3174-3177.(LI Gang,XIE Yun,CHEN Zheng-han.Formula of intermediate principal stress at failure for coherent soil inplane strain state[J].Chinese Journal of Rock Mechanicsand Enginerring,2004,23(18):3174-3177.(in Chinese))
[7]LEE K L.Comparison of plane strain and triaxial tests on sand[J].ASCE Journal of Soil Mechanics and Foundation Division,1970,96(SM3):901-923.
[8]YU M H,HE L N.A new model and theory on yield and failure of materials under the complex stress state[M]//Mechanical behavior of materials-VI.Oxford:Pergamon Press,1991:841-846.
[9]李广信,黄永男,张其光.土体平面应变方向上的主应力[J].岩土工程学报,2001,23(3):358-361.(LI Guang-xin,HUANG Yong-nan,ZHANG Qi-guang.The principal stress of soil in the direction of plane strain[J].Chinese Journal of Geotechnical Engineering,2001,23(3):358-361.(in Chinese))
[10]李广信,张其光,黄永男.等应力比平面应变试验中主应力转换的研究[J].岩土力学,2006,27(11):1867-1872.(LI Guang-xin,ZHANG Qi-guang,HUANG Yong-nan.Study on transforming of principal stresses in constant stress ration plane strain tests[J].Rock and Soil Mechanics,2006,27(11):1867-1872.(in Chinese))
[11]曹泽民.结构性对重塑黄土变形强度特性的影响[D].西安:西安理工大学,2013:56-65.(CAO Ze-min.The influence of structure on deformation and strength of remolded loess[D].Xi'an:Xi'an University of Technology,2013:56-65.(in Chinese))
[12]张玉,邵生俊.平面应变条件下黄土的竖向加载变形与强度特性分析[J].土木工程学报,2016,49(3):112-121.(An analysis of vertical loading deformation and strength characteristics of loess under plain strain condition[J].China Civil Engineering Journal,2016,49(3):112-121.(in Chinese))
[13]路德春,姚仰平,周安楠.土体平面应变条件下的主应力关系[J].岩石力学与工程学报,2006,25(11):2320-2326.(LU De-chun,YAO Yang-ping,ZHOU An-nan.Relationship between principal stresses of soil mass under plane strain condition[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(11):2320-2326.(in Chinese))
[14]俞茂宏,杨松岩,刘春阳,等.统一平面应变滑移线场理论[J].土木土程学报,1997,30(2):14-26,41.(YUMao-hong,YANG Song-yan,LIU Chun-yang,et al.Unified plane-strain slip line field theory system[J].China Civil Engineering Journal,1997,30(2):14-26,41.(in Chinese))