干湿循环下饱和红土不排水三轴试验研究
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摘要
以云南红土为研究对象,考虑干湿循环次数、干湿循环幅度等影响因素,利用TSZ-2型全自动三轴仪,开展干湿循环下饱和红土的不排水三轴试验,研究干湿循环作用对饱和红土剪切特性的影响。试验结果表明:不固结不排水条件下,随干湿循环次数增加和干湿循环幅度增大,饱和红土的应变软化现象增强,应力-应变曲线的初始斜率、孔压峰值增大,剪切峰值、峰值轴向应变、黏聚力、内摩擦角减小;干湿循环次数的影响大于干湿循环幅度的影响。干湿循环下饱和红土剪切特性变化的实质在于红土与水之间的相互作用,包括脱湿过程中水的逃逸作用、红土颗粒的吸附作用、红土体的硬化作用及收缩作用和吸湿过程中水的楔入作用、润滑作用、软化作用及红土体的膨胀作用,干湿循环过程中上述作用不断加深加剧,严重损伤了红土体的微结构,最终改变了饱和红土的不排水剪切特性。
The influence of drying-wetting cycle to the shear characteristic of saturated laterite is studied in this paper.Undrained triaxial tests of Yunnan laterite at drying-wetting cycle are performed using type TSZ-2 full automatic triaxial test apparatus.It considers drying-wetting cycle number and drying-wetting cycle amplitude.The results show that as the drying-wetting cycle number and the drying-wetting cycle amplitude increase,the strainsoftening phenomenon of saturated laterite generally enhances,the initial slope of stress-strain curve and pore water pressure peak increase,the peak shear strength and its corresponding axial strain,cohesion,internal friction angle decrease under unconsolidated undrained condition.The influence of drying-wetting cycle number is more obvious than that of its amplitude.Interaction between laterite and water is the essence of the change of shear characteristic of saturated laterite at drying-wetting cycle.They include the escape of water,the adsorption of laterite particles,hardening and shrinkage of laterite under the condition of dehydration and the wedging,lubricating,softening of water,expansion of laterite in the process of moistening.The deepening and intensifying of above actions at dryingwetting cycle can seriously damage the microstructure of laterite,ultimately change its shear characteristic.
The influence of drying-wetting cycle to the shear characteristic of saturated laterite is studied in this paper.Undrained triaxial tests of Yunnan laterite at drying-wetting cycle are performed using type TSZ-2 full automatic triaxial test apparatus.It considers drying-wetting cycle number and drying-wetting cycle amplitude.The results show that as the drying-wetting cycle number and the drying-wetting cycle amplitude increase,the strainsoftening phenomenon of saturated laterite generally enhances,the initial slope of stress-strain curve and pore water pressure peak increase,the peak shear strength and its corresponding axial strain,cohesion,internal friction angle decrease under unconsolidated undrained condition.The influence of drying-wetting cycle number is more obvious than that of its amplitude.Interaction between laterite and water is the essence of the change of shear characteristic of saturated laterite at drying-wetting cycle.They include the escape of water,the adsorption of laterite particles,hardening and shrinkage of laterite under the condition of dehydration and the wedging,lubricating,softening of water,expansion of laterite in the process of moistening.The deepening and intensifying of above actions at dryingwetting cycle can seriously damage the microstructure of laterite,ultimately change its shear characteristic.
引文
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Wang H Y,Tang S R,Xing Y H,et al.2015.Hydraulic conductivity of compacted wide grading gravel soils under freeze-thaw cycling[J].Journal of Engineering Geology,23(3):498~504.
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Wei X,Wang G.2014.Modeling swell-shrink behavior of compacted expansive clays subjected to cyclic drying and wetting[J].Chinese Journal of Geotechnical Engineering,36(8):1423~1431.
Wu J H,Yuan J P.2013.Field tests on expansive soil during wettingdrying cycles using large shear apparatus[J].Chinese Journal of Geotechnical Engineering,35(S1):103~107.
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邓欣.2013.干湿循环条件下云南红土的强度变形特性研究[D].昆明:昆明理工大学.
方庆军,洪宝宁,林丽贤,等.2011.干湿循环下高液限黏土与高液限粉土压缩特性比较研究[J].四川大学学报(工程科学版),43(增1):73~77.
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黄英,符必昌.1998.红土化作用及红土的工程地质特性研究[J].岩土工程学报,20(3):40~44.
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孙德安,黄丁俊.2015.干湿循环下南阳膨胀土的土水和变形特性[J].岩土力学,36(增1):115~119.
唐朝生,施斌.2011.干湿循环过程中膨胀土的胀缩变形特征[J].岩土工程学报,33(9):1376~1384.
王红雨,唐少容,邢毓航,等.2015a.冻融循环作用下宽级配砾质土的渗透特性[J].工程地质学报,23(3):498~504.
王红雨,朱洁,李雨佳,等.2015b.宽级配砾质土作为GCls防渗垫保护层的抗剪强度试验研究[J].工程地质学报,23(2):272~278.
魏星,王刚.2014.干湿循环作用下击实膨胀土胀缩变形模拟[J].岩土工程学报,36(8):1423~1431.
吴珺华,袁俊平.2013.干湿循环下膨胀土现场大型剪切试验研究[J].岩土工程学报,35(增1):103~107.
杨和平,肖夺.2005.干湿循环效应对膨胀土抗剪强度的影响[J].长沙理工大学学报(自然科学版),2(2):1~6.
杨俊,童磊,张国栋,等.2015.干湿循环机制下风化砂改良膨胀土的收缩特性[J].河海大学学报(自然科学版),43(2):150~155.
曾召田,吕海波,赵艳林,等.2012.膨胀土干湿循环效应及其对边坡稳定性的影响[J].工程地质学报,20(6):934~939.
Cheng J M,Wang Y M,Miao S C,et al.2014.Property study of solidified loess under wet-dry cycles[J].Journal of Engineering Geology,22(2):226~232.
Deng X.2013.Strength characteristics and deformation characteristics of Yunnan laterite under drying and wetting cycles[D].Kunming:Kunming University of Science and Technology.
Fang Q J,Hong B N,Lin L X,et al.2011.Study on the different compression characteristic of high liquid limit clay and high liquid limit silt on wetting-drying cycles[J].Journal of Sichuan University(Engineering Science Edition),43(S1):73~77.
He J L.2015.Researchon drying-wetting cycles of Yunnan reservoir laterite under reservoir water fluctuation[D].Kunming:Kunming University of Science and Technology.
Huang Y,Fu B C.1998.Research on laterization and specific property of laterite in engineering geology[J].Chinese Journal of Geotechnical Engineering,20(3):40~44.
Huang K,Wan J W,Chen G,et al.2012.Testing study of relationship between water content and shear strength of unsaturated soils[J].Rock and Soil Mechanics,33(9):2600~2604.
Liu H T,Zhang A J,Duan T,et al.2010.The influence of alternate drywet on the strength and permeability of remolded loess[J].Hydroscience and engineering,(4):38~42.
Robert W D.1994.Swell-shrink behavior of compacted clay[J].Journal of Geotechnical Engineering,120(3):618~623.
Sun D A,Huang D J.2015.Soil-water and deformation characteristics of Nanyang expansive soil after wetting-drying cycles[J].Rock and Soil Mechanics,36(S1):115~119.
Tang C S,Shi B.2011.Swelling and shrinkage behaviour of expansive soil during wetting-drying cycles[J].Chinese Journal of Geotechnical Engineering,33(9):1376~1384.
Wang H Y,Tang S R,Xing Y H,et al.2015.Hydraulic conductivity of compacted wide grading gravel soils under freeze-thaw cycling[J].Journal of Engineering Geology,23(3):498~504.
Wang H Y,Zhu J,Li Y J,et al.2015.Shear strength tests of compacted gravel soils for GCls protective layer[J].Journal of Engineering Geology,23(2):272~278.
Wei X,Wang G.2014.Modeling swell-shrink behavior of compacted expansive clays subjected to cyclic drying and wetting[J].Chinese Journal of Geotechnical Engineering,36(8):1423~1431.
Wu J H,Yuan J P.2013.Field tests on expansive soil during wettingdrying cycles using large shear apparatus[J].Chinese Journal of Geotechnical Engineering,35(S1):103~107.
Yang H P,Xiao D.2005.The influence of alternate dry-wet effect on the strength characteristic of expansive soils[J].Journal of Changsha University of Science and Technology(Natural Science),2(2):1~6.
Yang J,Tong L,Zhang G D,et al.2015.Shrinkage characteristics of expansive soil improved with weathered sand through wet-dry cycles[J].Journal of Hohai University(Natural Sciences),43(2):150~155.
Zeng Z T,LüH B,Zhao Y L,et al.2012.Wetting-drying effect of expansive soils and its influence on slope stability[J].Journal of Engineering Geology,20(6):934~939.
程佳明,王银梅,苗世超,等.2014.固化黄土的干湿循环特性研究[J].工程地质学报,22(2):226~232.
邓欣.2013.干湿循环条件下云南红土的强度变形特性研究[D].昆明:昆明理工大学.
方庆军,洪宝宁,林丽贤,等.2011.干湿循环下高液限黏土与高液限粉土压缩特性比较研究[J].四川大学学报(工程科学版),43(增1):73~77.
何金龙.2015.库水作用下云南库岸红土干湿循环特性研究[D].昆明:昆明理工大学.
黄英,符必昌.1998.红土化作用及红土的工程地质特性研究[J].岩土工程学报,20(3):40~44.
刘宏泰,张爱军,段涛,等.2010.干湿循环对重塑黄土强度和渗透性的影响[J].水利水运工程学报,(4):38~42.
孙德安,黄丁俊.2015.干湿循环下南阳膨胀土的土水和变形特性[J].岩土力学,36(增1):115~119.
唐朝生,施斌.2011.干湿循环过程中膨胀土的胀缩变形特征[J].岩土工程学报,33(9):1376~1384.
王红雨,唐少容,邢毓航,等.2015a.冻融循环作用下宽级配砾质土的渗透特性[J].工程地质学报,23(3):498~504.
王红雨,朱洁,李雨佳,等.2015b.宽级配砾质土作为GCls防渗垫保护层的抗剪强度试验研究[J].工程地质学报,23(2):272~278.
魏星,王刚.2014.干湿循环作用下击实膨胀土胀缩变形模拟[J].岩土工程学报,36(8):1423~1431.
吴珺华,袁俊平.2013.干湿循环下膨胀土现场大型剪切试验研究[J].岩土工程学报,35(增1):103~107.
杨和平,肖夺.2005.干湿循环效应对膨胀土抗剪强度的影响[J].长沙理工大学学报(自然科学版),2(2):1~6.
杨俊,童磊,张国栋,等.2015.干湿循环机制下风化砂改良膨胀土的收缩特性[J].河海大学学报(自然科学版),43(2):150~155.
曾召田,吕海波,赵艳林,等.2012.膨胀土干湿循环效应及其对边坡稳定性的影响[J].工程地质学报,20(6):934~939.