复杂应力条件下原状饱和海洋黏土孔压与强度特性
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摘要
利用土工静力–动力液压三轴–扭转多功能剪切仪,进行了非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,探讨了初始大主应力方向角、循环剪切荷载分量比值及循环应力水平对饱和海洋黏土孔压与强度特性的影响。结果表明:初始大主应力方向角对双向耦合剪切下孔压特性影响显著,随着角度的增大,残余孔压发展水平升高,同时波动孔压幅值也在增大,同时建立不同初始大主应力方向角下归一化残余孔压比与归一化循环次数比拟合关系。在固定加载路径所形成的椭圆面积不变条件下,竖向与扭转向荷载分量的比值存在某一临界值,对应此临界值,残余孔压最低。随着循环应力比的增大,波动孔压幅值与残余孔压均在增大,但高应力水平与低应力水平下孔压发展存在较大差异。此外由不同循环应力比下孔压时程曲线确定出临界循环应力比。初始大主应力方向角对动强度影响显著,随角度的增大动强度逐渐降低。动强度曲线显示循环应力比与循环剪切破坏次数的对数基本呈直线关系。
The apparatus for static and dynamic universal triaxial and torsional shear soil tests is employed to perform stress-controlled coupling vertical and torsional shear tests under different three-dimensional initial anisotropic consolidation stress conditions.Through experimental tests the effects of the initial orientation angle of the major principal stress,the ratio of the two stress components and the cyclic stress level on the pore water pressure and the strength of the saturated marine clay are examined.The initial orientation angle of the major principal stress has a significant influence on the characteristics of pore water pressure: as the angle increases,both the residual pore water pressure and the amplitude of fluctuated pore water pressure increase.Meanwhile,the relations between the normalized residual pore water pressure ratio and the cyclic number ratio with different initial orientation angles of the major principal stress are established.Under the conditions of keeping the area bounded by the elliptical stress path unchanged,there exists a certain critical value for the ratio of the axial and torsional shear stresses.At this critical value,the residual pore water pressure is the lowest.Both the fluctuated pore water pressure and the residual pore water pressure increase with increasing cyclic stress ratio.However,there is great difference between the high and the low stress levels.Furthermore,the critical cyclic stress ratio is determined according to the time history curves of pore water pressure under different cyclic stress ratios.The initial orientation angle of the major principal stress has a significant influence on the dynamic strength: as the angle increases,the dynamic strength decreases.The dynamic strength curve indicates that there is basically a linear relationship between the cyclic stress ratio and the logarithm of the cyclic number required at failure.
The apparatus for static and dynamic universal triaxial and torsional shear soil tests is employed to perform stress-controlled coupling vertical and torsional shear tests under different three-dimensional initial anisotropic consolidation stress conditions.Through experimental tests the effects of the initial orientation angle of the major principal stress,the ratio of the two stress components and the cyclic stress level on the pore water pressure and the strength of the saturated marine clay are examined.The initial orientation angle of the major principal stress has a significant influence on the characteristics of pore water pressure: as the angle increases,both the residual pore water pressure and the amplitude of fluctuated pore water pressure increase.Meanwhile,the relations between the normalized residual pore water pressure ratio and the cyclic number ratio with different initial orientation angles of the major principal stress are established.Under the conditions of keeping the area bounded by the elliptical stress path unchanged,there exists a certain critical value for the ratio of the axial and torsional shear stresses.At this critical value,the residual pore water pressure is the lowest.Both the fluctuated pore water pressure and the residual pore water pressure increase with increasing cyclic stress ratio.However,there is great difference between the high and the low stress levels.Furthermore,the critical cyclic stress ratio is determined according to the time history curves of pore water pressure under different cyclic stress ratios.The initial orientation angle of the major principal stress has a significant influence on the dynamic strength: as the angle increases,the dynamic strength decreases.The dynamic strength curve indicates that there is basically a linear relationship between the cyclic stress ratio and the logarithm of the cyclic number required at failure.
引文
[1]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.
[2]YAMAMOTO T,KONING H L,SPELLMEIGHER H.On the response of a poro-elastic bed to water waves[J].Journal of Fluid Mechanics,1978,78:193–206.
[3]钱寿易,楼志刚,杜金声.海洋波浪作用下土动力特性的研究现状和发展[J].岩土工程学报,1982,4(1):16–23.(QIAN Shou-yi,LOU Zhi-gang,DU Jin-sheng.State-of-the-art of dynamic characteristics of soil under ocean wave loading[J].Chinese Journal of Geotechnical Engineering,1982,4(1):16–23.(in Chinese))
[4]BOZORGNIA Y,NIAZI M,CAMPBELL K W.Characteristics of free-field vertical ground motion during the Northridge earthquake[J].Earthquake Spectra,1995,11(4):515–525.
[5]KALKAN E,GüLKAN P.Empirical attenuation equations for vertical ground motion in Turkey[J].Earthquake Spectra,2004,20(3):853–882.
[6]刘华北.水平与竖向地震作用下土工格栅加筋土挡墙动力分析[J].岩土工程学报,2006,28(5):594–599.(LIU Hua-bei.Analysis on seismic behavior of geogrid-reinforced retaining wall subjected to horizontal and vertical excitations[J].Chinese Journal of Geotechnical Engineering,2006,28(5):594–599.(in Chinese))
[7]蔡袁强,王军,海钧.双向激振循环荷载作用下饱和软黏土强度和变形特性研究[J].岩石力学与工程学报,2008,27(3):495–504.(CAI Yuan-qiang,WANG Jun,HAI Jun.Study on strength and deformation behaviors of soft clay under bidirectional exciting cyclic loading[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(3):495–504.(in Chinese))
[8]王洪瑾,马奇国,周景星,等.土在复杂应力状态下的动力特性研究[J].水利学报,1996,(4):57–72.(WANG Hong-jin,MA Qi-guo,ZHOU Jing-xing,et al.A study of dynamic characteristics of soil in complex stress state[J].Journal of Hydraulic Engineering,1996,(4):57–72.(in Chinese))
[9]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))
[10]郭莹,栾茂田,何杨,等.主应力方向循环变化对饱和松砂不排水动力特性的影响[J].岩土工程学报,2005,27(4):403–409.(GUO Ying,LUAN Mao-tian,HE Yang,et al.Effect of variation of principal stress orientation during cyclic loading on undrained dynamic behavior of saturated loose sands[J].Chinese Journal of Geotechnical Engineering,2005,27(4):403–409.(in Chinese))
[11]TOWHATA I,ISHIHARA K.Undrained strength of sand undergoing cyclic rotation of principal stress axes[J].Soils and Foundations,1985,25(2):135–147.
[12]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.
[13]SEED H B,PYKE R M,MARTIN G R.Effect of muti-directional shaking on liquefaction of sands[R].Berkeley:University of California,1975.
[14]ISHIHARA K,YAMAZAKI F.Cyclic simple shear tests on saturated sand in multi-directional loading[J].Soils and Foundations,1980,20(1):45–59.
[15]HAN L.Three-dimensional static and dynamic behavior of Kaolin clay with controlled microfabric using combined axial-torsional testing[D].Knoxville:The University of Tennessee,2003.
[16]沈扬,周建,龚晓南.主应力轴旋转对土体性状影响的试验进展研究[J].岩石力学与工程学报,2006,25(7):1408–1416.(SHEN Yang,ZHOU Jian,GONG Xiao-nan.Experimental progress research on influence of principal stress rotation on soils’characteristics[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(7):1408–1416.(in Chinese))
[17]沈扬,周建,张金良,等.考虑主应力方向变化的原状黏土强度及超静孔压特性研究[J].岩土工程学报,2007,29(6):843–847.(SHEN Yang,ZHOU Jian,ZHANG Jin-liang,et al.Research on strength and pore pressure of intact clay considering variation of principal stress direction[J].Chinese Journal of Geotechnical Engineering,2007,29(6):843–847.(in Chinese))
[18]沈扬,周建,龚晓南,等.主应力轴循环旋转对超固结黏土性状影响试验研究[J].岩土工程学报,2008,30(10):1514–1519.(SHEN Yang,ZHOU Jian,GONG Xiao-nan,et al.Influence of principal stress rotation on overconsolidated clay[J].Chinese Journal of Geotechnical Engineering,2008,30(10):1514–1519.(in Chinese))
[19]BOULANGER R W,CHAN C K,SEED H B,SEED R B.A low-compliance bi-directional cyclic simple shear appratus[J].Geotech Testing J,1993,16(1):36–45.
[20]栾茂田,金丹,许成顺,等.双向耦合剪切条件下饱和松砂的液化特性试验研究[J].岩土工程学报,2008,30(6):790–794.(LUAN Mao-tian,JIN Dan,XU Cheng-shun,et al.Liquefaction of sand under bi-directional cyclic loading[J].Chinese Journal of Geotechnical Engineering,2008,30(6):790–794.(in Chinese))
[21]栾茂田,金丹,张振东,等.饱和松砂的双向耦合剪切特性试验研究[J].岩土工程学报,2009,31(3):319–325.(LUAN Mao-tian,JIN Dan,ZHANG Zhen-dong,et al.Liquefaction of sand under bi-directional cyclic loading[J].Chinese Journal of Geotechnical Engineering,2009,31(3):319–325.(in Chinese))
[22]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))
[23]虞海珍,汪稔,赵文光,等.波浪荷载下钙质砂孔压增长特性的试验研究[J].武汉理工大学学报,2006,28(11):86–89.(YU Hai-zhen,WANG Ren,ZHAO Wen-guang,et al.Experimental research on development patten of pore water pressure of carbonate sand under wave loads[J].Journal of Wuhan University of Technology,2006,28(11):86–89.(in Chinese))
[24]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))
[25]聂影.复杂应力条件下饱和重塑黏土动力特性试验研究[D].大连:大连理工大学,2008.(NIE Ying.Experimental study on dynamic behavior of saturated clay under complex stress condition[D].Dalian:Dalian University of Technology,2008.(in Chinese))
[26]ZHOU Jian,GONG Xiao-nan.Strain degradation of saturated clay under cyclic loading[J].Canadian Geotechnical Journal,2001,38(1):208–212.
[27]栾茂田,齐剑峰,聂影,等.循环应力下饱和黏土剪切变形特性试验研究[J].海洋工程,2007,25(1):43–49.(LUAN Mao-tian,QI Jian-feng,NIE Ying,et al.Experimental study on shearing deformation behavior of saturated clay under cyclic stress[J].Ocean Engineering,2007,25(1):43–49.(in Chinese))
[2]YAMAMOTO T,KONING H L,SPELLMEIGHER H.On the response of a poro-elastic bed to water waves[J].Journal of Fluid Mechanics,1978,78:193–206.
[3]钱寿易,楼志刚,杜金声.海洋波浪作用下土动力特性的研究现状和发展[J].岩土工程学报,1982,4(1):16–23.(QIAN Shou-yi,LOU Zhi-gang,DU Jin-sheng.State-of-the-art of dynamic characteristics of soil under ocean wave loading[J].Chinese Journal of Geotechnical Engineering,1982,4(1):16–23.(in Chinese))
[4]BOZORGNIA Y,NIAZI M,CAMPBELL K W.Characteristics of free-field vertical ground motion during the Northridge earthquake[J].Earthquake Spectra,1995,11(4):515–525.
[5]KALKAN E,GüLKAN P.Empirical attenuation equations for vertical ground motion in Turkey[J].Earthquake Spectra,2004,20(3):853–882.
[6]刘华北.水平与竖向地震作用下土工格栅加筋土挡墙动力分析[J].岩土工程学报,2006,28(5):594–599.(LIU Hua-bei.Analysis on seismic behavior of geogrid-reinforced retaining wall subjected to horizontal and vertical excitations[J].Chinese Journal of Geotechnical Engineering,2006,28(5):594–599.(in Chinese))
[7]蔡袁强,王军,海钧.双向激振循环荷载作用下饱和软黏土强度和变形特性研究[J].岩石力学与工程学报,2008,27(3):495–504.(CAI Yuan-qiang,WANG Jun,HAI Jun.Study on strength and deformation behaviors of soft clay under bidirectional exciting cyclic loading[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(3):495–504.(in Chinese))
[8]王洪瑾,马奇国,周景星,等.土在复杂应力状态下的动力特性研究[J].水利学报,1996,(4):57–72.(WANG Hong-jin,MA Qi-guo,ZHOU Jing-xing,et al.A study of dynamic characteristics of soil in complex stress state[J].Journal of Hydraulic Engineering,1996,(4):57–72.(in Chinese))
[9]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))
[10]郭莹,栾茂田,何杨,等.主应力方向循环变化对饱和松砂不排水动力特性的影响[J].岩土工程学报,2005,27(4):403–409.(GUO Ying,LUAN Mao-tian,HE Yang,et al.Effect of variation of principal stress orientation during cyclic loading on undrained dynamic behavior of saturated loose sands[J].Chinese Journal of Geotechnical Engineering,2005,27(4):403–409.(in Chinese))
[11]TOWHATA I,ISHIHARA K.Undrained strength of sand undergoing cyclic rotation of principal stress axes[J].Soils and Foundations,1985,25(2):135–147.
[12]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.
[13]SEED H B,PYKE R M,MARTIN G R.Effect of muti-directional shaking on liquefaction of sands[R].Berkeley:University of California,1975.
[14]ISHIHARA K,YAMAZAKI F.Cyclic simple shear tests on saturated sand in multi-directional loading[J].Soils and Foundations,1980,20(1):45–59.
[15]HAN L.Three-dimensional static and dynamic behavior of Kaolin clay with controlled microfabric using combined axial-torsional testing[D].Knoxville:The University of Tennessee,2003.
[16]沈扬,周建,龚晓南.主应力轴旋转对土体性状影响的试验进展研究[J].岩石力学与工程学报,2006,25(7):1408–1416.(SHEN Yang,ZHOU Jian,GONG Xiao-nan.Experimental progress research on influence of principal stress rotation on soils’characteristics[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(7):1408–1416.(in Chinese))
[17]沈扬,周建,张金良,等.考虑主应力方向变化的原状黏土强度及超静孔压特性研究[J].岩土工程学报,2007,29(6):843–847.(SHEN Yang,ZHOU Jian,ZHANG Jin-liang,et al.Research on strength and pore pressure of intact clay considering variation of principal stress direction[J].Chinese Journal of Geotechnical Engineering,2007,29(6):843–847.(in Chinese))
[18]沈扬,周建,龚晓南,等.主应力轴循环旋转对超固结黏土性状影响试验研究[J].岩土工程学报,2008,30(10):1514–1519.(SHEN Yang,ZHOU Jian,GONG Xiao-nan,et al.Influence of principal stress rotation on overconsolidated clay[J].Chinese Journal of Geotechnical Engineering,2008,30(10):1514–1519.(in Chinese))
[19]BOULANGER R W,CHAN C K,SEED H B,SEED R B.A low-compliance bi-directional cyclic simple shear appratus[J].Geotech Testing J,1993,16(1):36–45.
[20]栾茂田,金丹,许成顺,等.双向耦合剪切条件下饱和松砂的液化特性试验研究[J].岩土工程学报,2008,30(6):790–794.(LUAN Mao-tian,JIN Dan,XU Cheng-shun,et al.Liquefaction of sand under bi-directional cyclic loading[J].Chinese Journal of Geotechnical Engineering,2008,30(6):790–794.(in Chinese))
[21]栾茂田,金丹,张振东,等.饱和松砂的双向耦合剪切特性试验研究[J].岩土工程学报,2009,31(3):319–325.(LUAN Mao-tian,JIN Dan,ZHANG Zhen-dong,et al.Liquefaction of sand under bi-directional cyclic loading[J].Chinese Journal of Geotechnical Engineering,2009,31(3):319–325.(in Chinese))
[22]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))
[23]虞海珍,汪稔,赵文光,等.波浪荷载下钙质砂孔压增长特性的试验研究[J].武汉理工大学学报,2006,28(11):86–89.(YU Hai-zhen,WANG Ren,ZHAO Wen-guang,et al.Experimental research on development patten of pore water pressure of carbonate sand under wave loads[J].Journal of Wuhan University of Technology,2006,28(11):86–89.(in Chinese))
[24]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))
[25]聂影.复杂应力条件下饱和重塑黏土动力特性试验研究[D].大连:大连理工大学,2008.(NIE Ying.Experimental study on dynamic behavior of saturated clay under complex stress condition[D].Dalian:Dalian University of Technology,2008.(in Chinese))
[26]ZHOU Jian,GONG Xiao-nan.Strain degradation of saturated clay under cyclic loading[J].Canadian Geotechnical Journal,2001,38(1):208–212.
[27]栾茂田,齐剑峰,聂影,等.循环应力下饱和黏土剪切变形特性试验研究[J].海洋工程,2007,25(1):43–49.(LUAN Mao-tian,QI Jian-feng,NIE Ying,et al.Experimental study on shearing deformation behavior of saturated clay under cyclic stress[J].Ocean Engineering,2007,25(1):43–49.(in Chinese))
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