复杂应力条件下饱和松砂单调与循环剪切特性的比较研究
|
摘要
本文利用大连理工大学新引进与开发的“土工静力-动力液压-三轴扭转多功能剪切仪”,针对福建标准砂,在不排水条件下同时进行了单调剪切试验与循环剪切试验,进而对其进行了对比分析。通过比较表明,应力-应变关系的应变软化和硬化特性与流滑变形和循环流动特性密切相关,当循环剪切应力水平高于单调剪切过程中应变软化阶段最小强度时将会发生流滑变形。无论在单调剪切中,还是在循环剪切中,稳定状态时的有效偏应力比随着大主应力方向与竖向之间夹角的增大而减小,在中主应力系数相同的条件下,循环剪切中呈现显著剪胀时的有效偏应力比和最终稳定状态时的有效偏应力比峰值分别与单调剪切中达到相变状态时的有效偏应力比和最终稳定有效偏应力比基本上一致。然而不排水条件下单调与循环剪切过程中孔隙水压力的增长特性却并不相同,循环剪切中的最大孔隙水压力随着初始主应力方向角的增大而减小,单调剪切中的最大孔隙水压力却随着主应力方向角的增大而增大。
In this paper,a comparative study on undrained monotonic and cyclic shear behavior of saturated loose sand under complex stress condition is made on the basis of experimental test by using the soil static and dynamic universal triaxial and torsional shear apparatus established in Dalian University of Technology.The different combinations of initial consolidation stress condition and monotonic or cyclic shear stress patterns are considered in the soil tests.It is shown through comparison that the strain-softening or hardening characteristics are closely associated with the deformation features of flow-slide deformation and the cyclic mobility of loose sands.Once the cyclic stress enters the strain-softening region given by monotonic shear loading,the flow-slide deformation will occur.In both monotonic and cyclic shear loading,the effective deviator stress ratio attained at the steady state reduces gradually with the increase of the orientation angle of major principal stress with respect to the vertical direction.Under the condition with the same coefficient of initial intermediate principal stress,the effective deviatoric stress ratio at which a remarkable shear dilation occurs and the effective deviatoric stress ratio peak at which a final steady state is formed in cyclic shear loading are respectively almost same as the effective deviatoric stress ratio at the arrival of phase transformation state and the finally attained steady effective deviatoric stress ratio.However,the behavior of generation and build-up of pore-water pressure is completely different in monotonic and cyclic shear loading.With the increase of the direction angle of initial principal stress,the maximum pore water pressure generated in the cyclic shear reduces gradually while the maximum pore water pressure caused by monotonic shear loading test increases gradually.
In this paper,a comparative study on undrained monotonic and cyclic shear behavior of saturated loose sand under complex stress condition is made on the basis of experimental test by using the soil static and dynamic universal triaxial and torsional shear apparatus established in Dalian University of Technology.The different combinations of initial consolidation stress condition and monotonic or cyclic shear stress patterns are considered in the soil tests.It is shown through comparison that the strain-softening or hardening characteristics are closely associated with the deformation features of flow-slide deformation and the cyclic mobility of loose sands.Once the cyclic stress enters the strain-softening region given by monotonic shear loading,the flow-slide deformation will occur.In both monotonic and cyclic shear loading,the effective deviator stress ratio attained at the steady state reduces gradually with the increase of the orientation angle of major principal stress with respect to the vertical direction.Under the condition with the same coefficient of initial intermediate principal stress,the effective deviatoric stress ratio at which a remarkable shear dilation occurs and the effective deviatoric stress ratio peak at which a final steady state is formed in cyclic shear loading are respectively almost same as the effective deviatoric stress ratio at the arrival of phase transformation state and the finally attained steady effective deviatoric stress ratio.However,the behavior of generation and build-up of pore-water pressure is completely different in monotonic and cyclic shear loading.With the increase of the direction angle of initial principal stress,the maximum pore water pressure generated in the cyclic shear reduces gradually while the maximum pore water pressure caused by monotonic shear loading test increases gradually.
引文
[1]Yosh im ine M,Ish ihara K,VargasW.E ffects of principal stress d irection and interm ed iate principal stress on undrained shear behavior of sand[J].Soils and Foundations,1998,38(3):179~188.
[2]汪闻韶.土的动力强度和液化特性[M].北京:中国电力出版社,1997.90~105.
[3]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.
[4]Ish ihara K.L iquefaction and flow failure during earthquakes[J].Geotechn ique,1993,43(3):351~415.
[5]Ish ihara K,Tatsuoka F,Yasuda S.Undrained deformation and liquefaction of sand under cyclic stresses[J].Soils and Foundations,1975,15(1):29~44
[6]L i X S,M ing H Y.Un ified modeling of flow liquefaction and cyclic mob ility[J].Soil Dynam ics and Engineering,2000,19:363~369
[7]郭莹,栾茂田,董秀竹,等.不同应力条件下砂土动模量特性的试验对比研究[J].水利学报,2003,(5):41~45.
[8]郭莹,栾茂田,许成顺,等.主应力方向变化对松砂不排水动强度特性的影响[J].岩土工程学报,2003,25(6):666~670.
[9]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):403~407.
[10]郭莹,栾茂田,何杨,等.复杂应力条件下饱和松砂孔隙水压力增长特性的试验研究[J].地震工程与工程振动,2004,24(3):139~144.
[11]何杨,栾茂田,许成顺,等.复杂应力条件下松砂振动孔隙水压力与体变特性的试验研究[J].地震工程与工程振动,2005,25(6):127~134.
[12]栾茂田,许成顺,何杨,等.主应力方向对饱和松砂不排水单调剪切特性影响的试验研究[J].岩土工程学报,2006,28(*):(待发表)
[13]许成顺,栾茂田,何杨,等.中主应力对饱和松砂不排水单调剪切特性的影响[J].岩土力学,2006,27(5):(待发表)
[14]Yosh im ine M,Ish ihara K.Flow potential of sand during liquefaction[J].Soils and Foundations,1998,38(3):189~198.
[15]HyodoM,Tan im izu H,Yasufuhu N,et al.Undrained cyclic and monoton ic triaxial behaviour of saturated loose sand[J].Soils and Foundations,1994,34(1):19~32.
[16]栾茂田,许成顺,何杨,等.静力与动力组合应力条件下饱和松砂变形特性的试验研究[J].土木工程学报,2005,38(3):83~89.
[2]汪闻韶.土的动力强度和液化特性[M].北京:中国电力出版社,1997.90~105.
[3]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.
[4]Ish ihara K.L iquefaction and flow failure during earthquakes[J].Geotechn ique,1993,43(3):351~415.
[5]Ish ihara K,Tatsuoka F,Yasuda S.Undrained deformation and liquefaction of sand under cyclic stresses[J].Soils and Foundations,1975,15(1):29~44
[6]L i X S,M ing H Y.Un ified modeling of flow liquefaction and cyclic mob ility[J].Soil Dynam ics and Engineering,2000,19:363~369
[7]郭莹,栾茂田,董秀竹,等.不同应力条件下砂土动模量特性的试验对比研究[J].水利学报,2003,(5):41~45.
[8]郭莹,栾茂田,许成顺,等.主应力方向变化对松砂不排水动强度特性的影响[J].岩土工程学报,2003,25(6):666~670.
[9]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):403~407.
[10]郭莹,栾茂田,何杨,等.复杂应力条件下饱和松砂孔隙水压力增长特性的试验研究[J].地震工程与工程振动,2004,24(3):139~144.
[11]何杨,栾茂田,许成顺,等.复杂应力条件下松砂振动孔隙水压力与体变特性的试验研究[J].地震工程与工程振动,2005,25(6):127~134.
[12]栾茂田,许成顺,何杨,等.主应力方向对饱和松砂不排水单调剪切特性影响的试验研究[J].岩土工程学报,2006,28(*):(待发表)
[13]许成顺,栾茂田,何杨,等.中主应力对饱和松砂不排水单调剪切特性的影响[J].岩土力学,2006,27(5):(待发表)
[14]Yosh im ine M,Ish ihara K.Flow potential of sand during liquefaction[J].Soils and Foundations,1998,38(3):189~198.
[15]HyodoM,Tan im izu H,Yasufuhu N,et al.Undrained cyclic and monoton ic triaxial behaviour of saturated loose sand[J].Soils and Foundations,1994,34(1):19~32.
[16]栾茂田,许成顺,何杨,等.静力与动力组合应力条件下饱和松砂变形特性的试验研究[J].土木工程学报,2005,38(3):83~89.
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心