含水量对软土无侧限变形影响的试验研究

Evaluation of Moisture Content on the Unconfined Compressive Strength of Soft Soils

在基槽开挖、基坑的放坡开挖或隧道掘进过程中,临空面附近的土体将发生应力卸荷,其土体由此产生较大的侧向变形,软土表现尤为明显。为了研究此类无侧限条件下软土的变形问题,采用了由常规固结仪改装而成的无侧限压缩试验仪,对原状软土及重塑土进行无侧限压缩试验。试验结果表明,每级荷载施加后,试样均表现出衰减蠕变的特征;与侧限条件相比,无侧限条件下的压缩应变率大大增加;此外,含水量和轴向应力对软土的变形均有很大的影响。通过试验数据拟合,得出了软土应变随含水量和轴向应力的变化关系。

The soil near the free face will experience the unloading stress in the excavation or tunneling,for which the soil mass will results in the lateral deformation,especially in soft soils.To study theadverse effect of soil deformation under the unconfined condition,a conventional consolidation test apparatus was modified to conduct the unconfined compression test for soft clays.A series of laboratory tests were conducted to investigate the characteristics of the unconfined compression of undisturbed samples as well as remodeling samples.The result shows that the samplespresentthe characteristics of attenuation creep under each loading stage.The strain rate under the unconfined condition is far greater than it under the unidirectional compression condition.Further,the water content and the axial stress have a great influence on the deformation of soft soil.The relationship between strain and water content and axial stress are obtained by statistically fitting test data.