应力路径对粉土力学特性的影响试验
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摘要
应力路径是影响土体强度和变形特性的重要因素,本文利用GDSTAS全自动三轴仪对苏北地区的粉土开展常规三轴压缩、减压三轴压缩、等压压缩3种应力路径的力学特性试验。结果表明:应力路径对粉土应力-应变特性影响显著,常规三轴压缩应力路径下应力-应变特性因围压大小而不同,等压压缩应力路径和减压压缩应力路径下粉土应力-应变特性都为应变软化型,但软化程度不同;不同应力路径下粉土的应力-应变特性可采用应变软化模型和双曲线模型进行拟合,拟合结果较好;相同围压下,常规三轴压缩应力路径下粉土强度最大,轴向应变的变化速率最快,等压压缩应力路径粉土强度次之,减压压缩应力路径强度最低,轴向应变的变化速率最慢。研究结果能为工程中不同应力路径下粉土地基设计计算提供较为可靠的力学指标。
The stress path is an important factor affecting soil strength and deformation characteristics. GDSTAS automatic triaxial instrument was used to carry out the mechanical test of three stress paths in Subei area, namely conventional tri-axial compression(CTC), reduced tri-axial pressure compression(RTC) and equal pressure compression(TC). Results showed that the stress path had a significant influence on the stress-strain characteristics of silty soil. Under the conventional tri-axial compression stress path, the stress-strain characteristics differed due to the different confining pressures, while under the equal pressure compression stress path and minus pressure compression stress path, it resembled strain softening type, and only the softening degree was different. The stress-strain characteristics of silt soil under different stress paths could be fitted using the strain softening model and the hyperbolic one, and the results were good. Under the conventional tri-axial compression stress path, the silty soil had the maximum strength and fastest change rate of axial stress strain for keeping same confining pressure, followed by the silty soil under the equal pressure compression stress path, while the silty soil had the lowest strength and change rate in axial stress strain under the minus pressure compression stress path. The results provided reliable mechanical indexes for the design and calculation of silt foundation under different stress paths in engineering.
The stress path is an important factor affecting soil strength and deformation characteristics. GDSTAS automatic triaxial instrument was used to carry out the mechanical test of three stress paths in Subei area, namely conventional tri-axial compression(CTC), reduced tri-axial pressure compression(RTC) and equal pressure compression(TC). Results showed that the stress path had a significant influence on the stress-strain characteristics of silty soil. Under the conventional tri-axial compression stress path, the stress-strain characteristics differed due to the different confining pressures, while under the equal pressure compression stress path and minus pressure compression stress path, it resembled strain softening type, and only the softening degree was different. The stress-strain characteristics of silt soil under different stress paths could be fitted using the strain softening model and the hyperbolic one, and the results were good. Under the conventional tri-axial compression stress path, the silty soil had the maximum strength and fastest change rate of axial stress strain for keeping same confining pressure, followed by the silty soil under the equal pressure compression stress path, while the silty soil had the lowest strength and change rate in axial stress strain under the minus pressure compression stress path. The results provided reliable mechanical indexes for the design and calculation of silt foundation under different stress paths in engineering.
引文
[1] LAMBE T W,MARR W A.Stress path method[J].Journal of Geotechnical and Geoenvironmental Engineering,1979,105(GT6):727.
[2] 符策简.高含盐粉土的力学特性试验研究[J].岩土力学,2010(增刊1):193.
[3] 彭芳乐,白小宇,雷亮.多种应力路径条件下上海粉细砂的室内试验[J].同济大学学报 (自然科学版),2011 (12):6.
[4] 施维成,朱俊高,张坤勇,等.平面应变条件下粗粒土的变形特性试验研究[J].岩土力学,2013,34(1):101.
[5] 路德春,姚仰平.黏土的应力路径本构模型[J].岩土力学,2007,28(4):649.
[6] WANG Y,TIAN H,FAN Y.Effect of stress paths on shear strength response of unsaturated gassy sand from Hangzhou metro project[C]//GeoShanghai International Conference.Shanghai:ASCE,2010.
[7] 黄质宏,朱立军,廖义玲,等.不同应力路径下红粘土的力学特性[J].岩石力学与工程学报,2004,23(15):2599.
[8] 江美英,骆亚生.应力路径对黄土结构性的影响[J].岩土力学,2009,30(增刊2):235.
[9] 殷德顺,王保田,王云涛.不同应力路径下的邓肯-张模型模量公式[J].岩土工程学报,2007,29(9):1380.
[10] 陈林靖,戴自航,刘志伟,应力路径对软土应力-应变特性影响试验研究[J].岩土力学,2011,32(11):3249.
[11] 董金梅,徐洪钟,朱定华,等.不同水环境下高分子材料改性粉土的试验研究[J].岩土工程学报,2013,35(7):1316.
[2] 符策简.高含盐粉土的力学特性试验研究[J].岩土力学,2010(增刊1):193.
[3] 彭芳乐,白小宇,雷亮.多种应力路径条件下上海粉细砂的室内试验[J].同济大学学报 (自然科学版),2011 (12):6.
[4] 施维成,朱俊高,张坤勇,等.平面应变条件下粗粒土的变形特性试验研究[J].岩土力学,2013,34(1):101.
[5] 路德春,姚仰平.黏土的应力路径本构模型[J].岩土力学,2007,28(4):649.
[6] WANG Y,TIAN H,FAN Y.Effect of stress paths on shear strength response of unsaturated gassy sand from Hangzhou metro project[C]//GeoShanghai International Conference.Shanghai:ASCE,2010.
[7] 黄质宏,朱立军,廖义玲,等.不同应力路径下红粘土的力学特性[J].岩石力学与工程学报,2004,23(15):2599.
[8] 江美英,骆亚生.应力路径对黄土结构性的影响[J].岩土力学,2009,30(增刊2):235.
[9] 殷德顺,王保田,王云涛.不同应力路径下的邓肯-张模型模量公式[J].岩土工程学报,2007,29(9):1380.
[10] 陈林靖,戴自航,刘志伟,应力路径对软土应力-应变特性影响试验研究[J].岩土力学,2011,32(11):3249.
[11] 董金梅,徐洪钟,朱定华,等.不同水环境下高分子材料改性粉土的试验研究[J].岩土工程学报,2013,35(7):1316.