上海软土非饱和压缩特征

Compressibility of Shanghai Unsaturated Soft Soil

摘要:

通过室内吸力控制的非饱和1维压缩试验,获得了上海软土在不同吸力下的压缩—回弹—再压缩曲线,进而获取了非饱和土2个重要压缩性指标——回弹指数和压缩指数;分析探讨了基质吸力对非饱和土强度的影响,并采用Alonso弹塑性模型对试验实测数据进行了拟合分析,获取了前期固结压力随基质吸力的变化关系曲线.试验结果表明,随着基质吸力的增加,土的压缩性不断降低;当前吸力条件下,孔隙比随竖向压力变化曲线阶段特征明显,包括弹性阶段、弹塑性阶段以及回弹与再压缩阶段;非饱和压缩过程中,前期固结压力随基质吸力减小而减小,土的孔隙比与基质吸力和竖向应力之间呈曲面关系.

Abstract:

Based on onedimensional compression tests,compressionreboundcompression curve and the compression index and rebound index of Shanghai soft soil were obtained.At the same time,the influences of suction on the strength of the unsaturated soil were analyzed.Then the test results were simulated with Alonso elasticplastic model,and the preconsolidation pressure versus suction (loadingcollapse curve) curve was fitted.Results show that the compressibility of the soil decreases while the matric suction increases.For certain suctions,elg p curve clearly step phases in elastic,elasticplastic and rebound recompressed phases.With compression of unsaturated soil,the preconsolidation pressure decreases with suction decreases.There is a surface among pore ration,suction and vertical stress.