摘要
为了研究吸力变化对非饱和膨胀土变形和抗剪强度特性的影响,利用三套新研制的双压力室非饱和土三轴仪,进行一系列吸湿试验、等吸力压缩固结试验和等吸力剪切试验。试验土样取自鄂西北的中膨胀性土,采用静力压实方法制备试样。试验成果表明:该非饱和膨胀土在低围压吸湿过程中的体变性状呈明显的屈服特性,因此验证了Barcelona膨胀土本构模型中SD屈服包线的存在。在等向压缩固结过程中,该非饱和膨胀土的屈服应力随吸力增加而增大,而屈服后的压缩系数随吸力增大而减少,表明吸力对土体具有硬化作用。该非饱和膨胀土的有效内摩擦角不随吸力变化而变化,吸力对抗剪强度的贡献(似凝聚力)随吸力呈非线性增加,吸力对该膨胀土抗剪强度的贡献明显高于压实高岭土和砂性土。
A laboratory testing program was carded out to investigate the mechanical behavior of a medium unsaturated expansive clay taken from Hubei. Statically compacted specimens were used in this testing program, which was performed using three newly developed double-cell triaxial systems for unsaturated soils. The stress paths adopted in the testing program included wetting under isotropic stress condition, isotropic compression and sheafing under different values of constant suction. The test results showed that the recompacted expansive clay exhibited an elasto-plastic swelling upon wetting at a low confining pressure, indicating the existence of the Suction-Decrease （SD） yield locus. Within the suction range considered （0 to 200 kPa）, both the yield stress and the post-yield stiffness increased with suction, suggesting a suction-hardening effect on the soil behavior. The slope of critical state hyperlines in （q, p） plane was independent on the value of suction within the suction range considered, The contribution of suction to shear strength for this expansive clay was more significant than that of a compacted kaolin.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2006年第2期196-201,共6页
Chinese Journal of Geotechnical Engineering
基金
香港政府研究基金局(RGC)资助项目(HKUST6108/99E)
关键词
膨胀土
吸力
三轴试验
变形
抗剪强度
expansive soils
suction
triaxial test
deformation
shear strength
