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通过SPAX-2000动静真三轴测试系统,研究了饱和软黏土在冲击荷载作用下的应力、应变、孔隙水压力等指标的变化特征。同时,通过差热分析法和理论计算,对比了试验前后软土中结合水含量大小。研究表明,土中结合水含量及其变化对土的物理性质和力学行为有重要影响。试验前后饱和软黏土中结合水含量变化较大,水性转化现象明显,土体固结作用显著,并且冲击荷载作用下土中水性转化、弱结合水排出与动力排水固结程度有因果联系。在一定试验条件组合下,存在饱和冲击能,此时能激发土中结合水转化为自由水量最多;伴随孔隙压力的消散和土体的固结,土的抗剪强度提高、压缩性减小,土体成为超固结土。该研究能揭示软基加固的微观机理,可为静动力排水固结法设计提供理论依据。
By SPAX-2000 dynamic and static true triaxial test system, the change characteristics of saturated soft clay under the impact load of stress, strain, pore water pressure and other indicators were studied. At the same time, the difference between the water content in soft soil before and after the test was compared by differential thermal analysis and theoretical calculation. The research shows that the content of bound water in the soil and its variation have an important influence on the physical properties and mechanical behavior of the soil. Before and after the experiment, the content of bound water in saturated soft clay changed greatly, the phenomenon of water conversion was obvious, and the consolidation effect of soil was remarkable. Under the action of impact load, there was a causal relationship between water-borne conversion and weakly bound water discharge and dynamic drainage consistency. Under certain experimental conditions, there exists saturated impact energy, which can stimulate the conversion of bound water into free water in the most. With the dissipation of pore pressure and soil consolidation, the shear strength of soil increases and the compressibility decreases. Soil to become over-consolidated soil. This study can reveal the microscopic mechanism of soft foundation reinforcement and provide a theoretical basis for the design of static and dynamic drainage consolidation.