双向耦合剪切条件下饱和松砂的液化特性试验研究
摘要
为了模拟海床及海洋建筑物遭受波浪荷载时所引起的循环应力,进行了一系列均等固结条件下的应力控制式轴向–扭转双向耦合循环剪切试验。加载路径在σd/2-τ应力空间内为椭圆。试验在保证椭圆面积不变的情况下,分别变化竖向和扭转向的荷载分量幅值,以此来探讨双向耦合剪切试验中各个分量的变化对饱和松砂的循环强度特性的影响。试验结果表明砂土在双向耦合荷载作用下,其液化强度与加载椭圆路径的面积和两个荷载分量比值密切相关。当轴向应力与剪应力幅值的比值保持不变时,砂土液化强度随着椭圆面积的增大而降低。而在椭圆面积保持不变时,当竖向与扭转向荷载分量的比值小于某一临界值0.6～0.75时,砂土液化强度随着比值的增加而增大,当竖向与扭转向荷载分量的比值大于某一临界值0.6～0.75时,砂土的液化强度随着比值的增加而减小,在临界值0.6～0.75之间表现出最高的强度。另外,在一个周期内孔隙水压力的循环变化与轴向应力相位一致,与循环剪应力相位相差90。
A set of stress controlled bi-directional cyclic loading tests under isotropic consolidated condition was conducted for simulating the cyclic stress induced by wave loading.The stress path followed during the test in terms of σ d /2 and τ was controlled in shape of ellipse.The area bounded by the elliptical stress path was kept unchanged while the amplitude of the axial and torsional shear stresses were varied to study the effect of two components on the strength and deformation behavior of saturated loose sand.It was shown that the resistance to liquefaction of saturated sand was considerably related with both the area of elliptical stress path and the ratio of the two stress components.For the same ratio of two stress components,the resistance to liquefaction of saturated sand decreased with the increasing area of the elliptical stress path.However,for the same area of elliptical stress path,the sand might exhibit the highest resistance to liquefaction at a critical ratio of axial and torsional shear stresses,0.6~0.75.The resistance to liquefaction increased with the increasing ratio of σ d /2 and τ when the ratio was less than the critical value,and decreased with the increasing ratio of σ d /2 and τ when the ratio was larger than the critical value.Moreover,the pore water pressure developed gradually to the initial effective confining pressure with transient fluctuation and phase matching axial load.
A set of stress controlled bi-directional cyclic loading tests under isotropic consolidated condition was conducted for simulating the cyclic stress induced by wave loading.The stress path followed during the test in terms of σ d /2 and τ was controlled in shape of ellipse.The area bounded by the elliptical stress path was kept unchanged while the amplitude of the axial and torsional shear stresses were varied to study the effect of two components on the strength and deformation behavior of saturated loose sand.It was shown that the resistance to liquefaction of saturated sand was considerably related with both the area of elliptical stress path and the ratio of the two stress components.For the same ratio of two stress components,the resistance to liquefaction of saturated sand decreased with the increasing area of the elliptical stress path.However,for the same area of elliptical stress path,the sand might exhibit the highest resistance to liquefaction at a critical ratio of axial and torsional shear stresses,0.6~0.75.The resistance to liquefaction increased with the increasing ratio of σ d /2 and τ when the ratio was less than the critical value,and decreased with the increasing ratio of σ d /2 and τ when the ratio was larger than the critical value.Moreover,the pore water pressure developed gradually to the initial effective confining pressure with transient fluctuation and phase matching axial load.
引文
[1]MADSEN O S.Wave-induced pore-pressure and effective stresses in a porous bed[J].Geotechnique,1978,28(4):435–440.
[2]ISHIHARA K,TOWHATA I.Sand response to cyclic rotation of principal stress directions as induced by wave loads[J].Soils and Foundations,1983,23(4):11–26.
[3]许成顺.复杂应力条件下饱和松砂剪切特性及本构模型的试验验证[D].大连:大连理工大学,2006.(XU Cheng-shun.Experimental study on behavior of saturated loose sands under complex shear loading and constitutive model[D].Dalian:Dalian University of Technology,2006.(in Chinese))
[4]何杨.复杂应力条件下饱和砂土孔隙水压力及体变特性研究[D].大连:大连理工大学,2007.(HE Yang.Experimental study on pore water pressure and volumetric strain characteristics of saturated sands under complex stress condition[D].Dalian:Dalian University of Technology,2007.(in Chinese))
[5]SEED H B,PYKE R M,MARTIN G R.Effect of multi-directional shaking on liquefaction of sands[R].Berkeley:University of California,1975.
[6]BOULANGER R W,SEED R B.Liquefaction of sand under bi-directional monotonic and cyclic loading[J].Journal of Geotechnical Engineering,ASCE,1995,121(12):870–878.
[7]沈瑞福,王洪瑾,周克骥,周景星.动主应力旋转下砂土孔隙水压力发展及海床稳定性判断[J].岩土工程学报,1994,16(3):70–78.(SHEN Rui-fu,WANG Hong-jin,ZHOU Ke-ji,ZHOU Jing-xing.Building-up of pore water pressure under cyclic rotation of principal stress and evaluation of stability of seabed deposit[J].Chinese Journal of Geotechnical Engineering,1994,16(3):70–78.(in Chinese))
[8]姚仰平.真三轴应力条件下砂土的非线性动力本构关系的研究[D].西安:西安理工大学,1995.(YAO Yang-ping.Nonlinear dynamic constitutive relation of sand under real triaxial stress condition[D].Xi′an:Xi′an University of Technology,1995.(in chinese))
[9]郭莹.复杂应力条件下饱和松砂的不排水动力特性试验研究[D].大连:大连理工大学,2003.(GUO Ying.Experimental studies on undrained cyclic behavior of loose sands under complex stress conditions considering static and cyclic coupling effect[D].Dalian:Dalian University of Technology,2003.(in Chinese))
[10]林淋.竖向地震动特征分析[D].北京:中国地震局工程力学研究所,2005.(LIN Lin.Characteristics analysis of vertical ground motion[D].Beijing:China Seismological Bureau,2005.(in Chinese))
[11]周正华,周雍年,卢涛,杨程.竖向地震动特征研究[J].地震工程与工程振动,2003,23(3):25–29.(ZHOU Zheng-hua,ZHOU Yong-nian,LU Tao,YANG Cheng.Study on characteristics of vertical ground motion[J].Chinese Journal of Earthquake Engineering and Engineering Vibration,2003,23(3):25–29.(in Chinese))
[12]BOULANGER R W,CHAN C K,SEED H B,SEED R B.A low-compliance bi-directional cyclic simple shear apparatus[J].Geotech Testing J,1993,16(1):36–45.
[13]栾茂田,郭莹,李木国,等.土工静力–动力液压三轴–扭转多功能剪切仪研发及应用[J].大连理工大学学报,2003,43(5):670–675.(LUAN Mao-tian,GUO Ying,LI Mu-guo,et al.Development and application of soil static and dynamic universal triaxial and torsional shear apparatus[J].Journal of Dalian University of Technology,2003,43(5):670–675.(in chinese))
[14]SEED H B,LEE K L.Liquefaction of saturated sands during cyclic loading[J].Journal of the Soil Mechanics and Foundation Engineering Division,ASCE,1966,92(SM6):105–134.
[2]ISHIHARA K,TOWHATA I.Sand response to cyclic rotation of principal stress directions as induced by wave loads[J].Soils and Foundations,1983,23(4):11–26.
[3]许成顺.复杂应力条件下饱和松砂剪切特性及本构模型的试验验证[D].大连:大连理工大学,2006.(XU Cheng-shun.Experimental study on behavior of saturated loose sands under complex shear loading and constitutive model[D].Dalian:Dalian University of Technology,2006.(in Chinese))
[4]何杨.复杂应力条件下饱和砂土孔隙水压力及体变特性研究[D].大连:大连理工大学,2007.(HE Yang.Experimental study on pore water pressure and volumetric strain characteristics of saturated sands under complex stress condition[D].Dalian:Dalian University of Technology,2007.(in Chinese))
[5]SEED H B,PYKE R M,MARTIN G R.Effect of multi-directional shaking on liquefaction of sands[R].Berkeley:University of California,1975.
[6]BOULANGER R W,SEED R B.Liquefaction of sand under bi-directional monotonic and cyclic loading[J].Journal of Geotechnical Engineering,ASCE,1995,121(12):870–878.
[7]沈瑞福,王洪瑾,周克骥,周景星.动主应力旋转下砂土孔隙水压力发展及海床稳定性判断[J].岩土工程学报,1994,16(3):70–78.(SHEN Rui-fu,WANG Hong-jin,ZHOU Ke-ji,ZHOU Jing-xing.Building-up of pore water pressure under cyclic rotation of principal stress and evaluation of stability of seabed deposit[J].Chinese Journal of Geotechnical Engineering,1994,16(3):70–78.(in Chinese))
[8]姚仰平.真三轴应力条件下砂土的非线性动力本构关系的研究[D].西安:西安理工大学,1995.(YAO Yang-ping.Nonlinear dynamic constitutive relation of sand under real triaxial stress condition[D].Xi′an:Xi′an University of Technology,1995.(in chinese))
[9]郭莹.复杂应力条件下饱和松砂的不排水动力特性试验研究[D].大连:大连理工大学,2003.(GUO Ying.Experimental studies on undrained cyclic behavior of loose sands under complex stress conditions considering static and cyclic coupling effect[D].Dalian:Dalian University of Technology,2003.(in Chinese))
[10]林淋.竖向地震动特征分析[D].北京:中国地震局工程力学研究所,2005.(LIN Lin.Characteristics analysis of vertical ground motion[D].Beijing:China Seismological Bureau,2005.(in Chinese))
[11]周正华,周雍年,卢涛,杨程.竖向地震动特征研究[J].地震工程与工程振动,2003,23(3):25–29.(ZHOU Zheng-hua,ZHOU Yong-nian,LU Tao,YANG Cheng.Study on characteristics of vertical ground motion[J].Chinese Journal of Earthquake Engineering and Engineering Vibration,2003,23(3):25–29.(in Chinese))
[12]BOULANGER R W,CHAN C K,SEED H B,SEED R B.A low-compliance bi-directional cyclic simple shear apparatus[J].Geotech Testing J,1993,16(1):36–45.
[13]栾茂田,郭莹,李木国,等.土工静力–动力液压三轴–扭转多功能剪切仪研发及应用[J].大连理工大学学报,2003,43(5):670–675.(LUAN Mao-tian,GUO Ying,LI Mu-guo,et al.Development and application of soil static and dynamic universal triaxial and torsional shear apparatus[J].Journal of Dalian University of Technology,2003,43(5):670–675.(in chinese))
[14]SEED H B,LEE K L.Liquefaction of saturated sands during cyclic loading[J].Journal of the Soil Mechanics and Foundation Engineering Division,ASCE,1966,92(SM6):105–134.
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