静动应力下正常固结黏土循环特性研究
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摘要
利用动三轴仪对天津正常固结饱和黏土进行循环剪切试验,重点研究静偏应力与动应力组合作用下土体动变形、动弹性模量及动孔压的变化规律。结果表明静偏应力对黏土循环特性影响显著。静偏应力为0时,土体产生拉应变,其随动应力增加不断增大,量级为10-3。静偏应力大于0时,土体产生压应变,此时若动静应力比小于1,压应变随动应力增加不断增大;若动静应力比大于1,压应变不断减小。相同静偏应力下,动弹性模量随动应力增加不断减小;相同动应力下,动弹性模量随静偏应力增加不断减小,且土体更易发生应变软化。静偏应力为0或为拉时,动孔压在-1~1 kPa范围波动。
The cyclic shear tests were performed on the normal consolidated saturated clay from Tianjin with the dynamic triaxial system. The development of the dynamic deformation,the elastic modulus and the pore pressure under the coupled effect of static and dynamic stresses was the focus of the investigation. The test results indicated that the dynamic properties of the soft clay were significantly influenced by the static deviatoric stress. When the static stress σ0 was 0,the tensile strain was generated and increased continuously with the increasing of dynamic stress σd,and the magnitude of the tensile strain was at the scale of 10-3. When the stress was larger than 0,the compressive strain was increased with the increasing of dynamic stress if σd/σ0<1 and decreased if σd/ σ0>1.Under the same static stress, the dynamic elastic modulus decreased with the increasing of dynamic stress.Whereas under the same dynamic stress,the dynamic elastic modulus decreased continuously with the increasing of static stress. Besides, the larger the static stress, the more likely for the strain softening to occur. The pore pressure fluctuated in-1–1 k Pa when the static stress was 0 or tensile.
The cyclic shear tests were performed on the normal consolidated saturated clay from Tianjin with the dynamic triaxial system. The development of the dynamic deformation,the elastic modulus and the pore pressure under the coupled effect of static and dynamic stresses was the focus of the investigation. The test results indicated that the dynamic properties of the soft clay were significantly influenced by the static deviatoric stress. When the static stress σ0 was 0,the tensile strain was generated and increased continuously with the increasing of dynamic stress σd,and the magnitude of the tensile strain was at the scale of 10-3. When the stress was larger than 0,the compressive strain was increased with the increasing of dynamic stress if σd/σ0<1 and decreased if σd/ σ0>1.Under the same static stress, the dynamic elastic modulus decreased with the increasing of dynamic stress.Whereas under the same dynamic stress,the dynamic elastic modulus decreased continuously with the increasing of static stress. Besides, the larger the static stress, the more likely for the strain softening to occur. The pore pressure fluctuated in-1–1 k Pa when the static stress was 0 or tensile.
引文
[1]冯军.长江口软黏土地基在波浪循环荷载作用下的弱化分析[硕士学位论文][D].天津:天津大学,2004.(FENG Jun.Degradation study of the soft clay foundation of Yangtze estuary waterway[M.S.Thesis][D].Tianjin:Tianjin University,2004.(in Chinese))
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[8]温日琨,王常晶,陈云敏.交通荷载引起的静偏应力对饱和软粘土变形影响[J].岩土力学,2009,30(增2):119–122.(WEN Rikun,WANG Changjing,CHEN Yunmin.Effect of traffic loading induced static deviator stress on deformation of saturated soft clay[J].Rock and Soil Mechanics,2009,30(Supp.2):119–122.(in Chinese))
[9]齐剑峰,栾茂田,王忠涛,等.静动应力作用下大连饱和黏土的剪切特性研究[J].地震工程与工程振动,2011,31(1):148–154.(QI Jianfeng,LUAN Maotian,WANG Zhongtao,et al.A study on shearing behavior of saturated clay under action of static and dynamic stresses[J].Journal of Earthquake Engineering and Engineering Vibration,2011,31(1):148–154.(in Chinese))
[10]闫澍旺,封晓伟,田俊峰.循环荷载下滨海软黏土孔压发展规律及强度弱化特性[J].中国港湾建设,2010,169(增1):86–89.(YAN Shuwang,FENG Xiaowei,TIAN Junfeng.Pore pressure development and strength softening character of littoral soft clay under cyclic loading[J].China Harbour Engineering,2010,169(增1):86–89.(in Chinese))
[11]IDRISS I M,DOBRY R,SINGH R D.Nonlinear behavior of soft clays during cyclic loading[J].Journal of Soil Mechanics and Foundation,1978,104(12):1 427–1 447.
[12]霍海峰.循环荷载作用下饱和黏土的力学性质研究[博士学位论文][D].天津:天津大学,2012.(HUO Haifeng.Research on the mechanical property of saturated silty clay under cyclic loading[Ph.D.Thesis][D].Tianjin:Tianjin University,2012.(in Chinese))
[2]叶耀东,朱合华,王如路.软土地铁运营隧道病害现状及成因分析[J].地下空间与工程学报,2007,3(1):157–160.(YE Yaodong,ZHU Hehua,WANG Rulu.Analysis of the current status of metro operating tunnel damage in soft ground and its causes[J].Chinese Journal of Underground Space and Engineering,2007,3(1):157–160.(in Chinese))
[3]HYODO M,YAMAMOTO Y,SUGIYAMA M.Undrained cyclic shear behavior of normally consolidated clay subjected to initial static shear stress[J].Soils and Foundations,1994,34(4):1–11.
[4]HYODO M,HYDE A F L,YAMAMOTO Y,et al.Cyclic shear strength of undisturbed and remoulded marine clays[J].Soils and Foundations,1999,39(2):45–58.
[5]BISCONTIN G.Modeling the dynamic behavior of lightly over consolidated soil deposits on submarine slope[Ph.D.Thesis][D].Berkeley:University of California,2001.
[6]HSU C C,VUCETIC M.Threshold shear strain for cyclic Pore-water pressure in cohesive soils[J].Journal of Geotechnical and Geoenvironmental Engineering,2006,132(10):1 325–1 335.
[7]王常晶,陈云敏.交通荷载引起的静偏应力对饱和软黏土不排水循环性状影响的试验研究[J].岩土工程学报,2007,29(11):1 742–1 747.(WANG Changjing,CHEN Yunmin.Study on effect of traffic loading induced static deviator stress on undrained cyclic properties of saturated soft clay[J].Chinese Journal of Geotechnical Engineering,2007,29(11):1 742–1 747.(in Chinese))
[8]温日琨,王常晶,陈云敏.交通荷载引起的静偏应力对饱和软粘土变形影响[J].岩土力学,2009,30(增2):119–122.(WEN Rikun,WANG Changjing,CHEN Yunmin.Effect of traffic loading induced static deviator stress on deformation of saturated soft clay[J].Rock and Soil Mechanics,2009,30(Supp.2):119–122.(in Chinese))
[9]齐剑峰,栾茂田,王忠涛,等.静动应力作用下大连饱和黏土的剪切特性研究[J].地震工程与工程振动,2011,31(1):148–154.(QI Jianfeng,LUAN Maotian,WANG Zhongtao,et al.A study on shearing behavior of saturated clay under action of static and dynamic stresses[J].Journal of Earthquake Engineering and Engineering Vibration,2011,31(1):148–154.(in Chinese))
[10]闫澍旺,封晓伟,田俊峰.循环荷载下滨海软黏土孔压发展规律及强度弱化特性[J].中国港湾建设,2010,169(增1):86–89.(YAN Shuwang,FENG Xiaowei,TIAN Junfeng.Pore pressure development and strength softening character of littoral soft clay under cyclic loading[J].China Harbour Engineering,2010,169(增1):86–89.(in Chinese))
[11]IDRISS I M,DOBRY R,SINGH R D.Nonlinear behavior of soft clays during cyclic loading[J].Journal of Soil Mechanics and Foundation,1978,104(12):1 427–1 447.
[12]霍海峰.循环荷载作用下饱和黏土的力学性质研究[博士学位论文][D].天津:天津大学,2012.(HUO Haifeng.Research on the mechanical property of saturated silty clay under cyclic loading[Ph.D.Thesis][D].Tianjin:Tianjin University,2012.(in Chinese))
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