CAJ | 학술논문

对经历较广吸力范围内不同吸力历史的非饱和弱膨胀土进行了一系列吸力控制的三轴剪切试验。关于最大吸力的施加，高吸力采用蒸汽平衡法；较低吸力采用轴平移技术。试验结果表明：在净应力和吸力相同条件下，经过湿化试样的应力-应变关系曲线升高、剪缩体变小；经过高吸力试样的应力-应变关系曲线也升高、剪缩体变小，随着经历过最大吸力的增加其应力比-应变关系、体变表现出的超固结土特性明显。其主要原因是前期试样受过较大的吸力，相当于受过较大前期固结压力，同时弱膨胀土失水收缩性明显，经过较大吸力后试样孔隙比明显减小，使试样剪切过程中表现出超固结黏土的特性。因此，讨论非饱和弱膨胀性土的应力-应变关系和强度时需考虑吸力历史引起的体积收缩影响。
대경력교엄흡력범위내불동흡력역사적비포화약팽창토진행료일계렬흡력공제적삼축전절시험。관우최대흡력적시가，고흡력채용증기평형법；교저흡력채용축평이기술。시험결과표명：재정응력화흡력상동조건하，경과습화시양적응력-응변관계곡선승고、전축체변소；경과고흡력시양적응력-응변관계곡선야승고、전축체변소，수착경력과최대흡력적증가기응력비-응변관계、체변표현출적초고결토특성명현。기주요원인시전기시양수과교대적흡력，상당우수과교대전기고결압력，동시약팽창토실수수축성명현，경과교대흡력후시양공극비명현감소，사시양전절과정중표현출초고결점토적특성。인차，토론비포화약팽창성토적응력-응변관계화강도시수고필흡력역사인기적체적수축영향。
The suction-controlled triaxial shear tests were conducted on unsaturated weakly-expansive soil experiencing different suction histories over a wide range of suction. The maximum suction was applied by using the vapor equilibrium method for high suction and the axis translation technique at low suction. The results show that at the same net stress and suction, the stress-strain curves of the specimens subjected to drying-wetting cycle are situated at a higher level and a smaller contractive volumetric strain occurs during shearing, and the stress-strain curves of the specimens experiencing larger suction also raise up and a smaller contractive volumetric strain can be observed during shearing. Furthermore, the stress-strain and volumetric strain behaviors become more and more similar to the deformation characteristics of overconsolidated soil with the increase of the imposed maximum suction. The reason for the above phenomena is that the specimen experiences a larger suction as the specimen experiences a larger pre-consolidation pressure. Meanwhile, the shrinkage characteristics of weakly-expansive soil become significant due to water loss. After experiencing a larger suction, the void ratio decreases significantly, and thus the specimen exhibits the deformation characteristics similar to the overconsolidated clay during shearing. Therefore, in order to characterize the stress-strain relationship and the strength of unsaturated weakly-expansive soil, the specimen volumetric shrinkage caused by suction history should be considered.