Correlation between mechanical properties and microstructure parameters of soft dredger fill under the coupling action of consolidation and load
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摘要: 固结条件与荷载条件对吹填土的力学特性具有明显的影响，且土的微观结构特征是决定其宏观力学性质的本质因素，为了研究吹填软土力学特性在不同固结条件和荷载条件下的变化规律及与微结构参数的关联性，对天津滨海新区重塑吹填软土进行不同初始固结条件与荷载效应综合作用下的蠕变试验和微观结构测试，研究此条件下吹填土力学特性的变化规律，并通过灰色关联度理论建立宏观力学参数与微结构参数之间的关联性。试验结果表明：稳定性蠕变对吹填软土强度的增长起到积极作用，有偏压固结较无偏压固结强度增长更快，且初始固结越充分，强度增长越快；随蠕变时间的增加，颗粒的等效直径、形态比和圆度呈增大的趋势，而颗粒和孔隙的数量与周长、孔隙的等效直径、形态比和圆度则呈减小的趋势；抗剪强度指标C，φ值随颗粒等效直径、形态比和圆度的增大而增大，但随颗粒和孔隙的数量与周长、孔隙的等效直径、形态比和圆度的增大而减小。关联度分析表明，颗粒（孔隙）等效直径和圆度是影响吹填土力学性质演化的重要微结构参数，固结与蠕变越充分，土体微结构参数调整越稳定，强度越高。Abstract: The consolidation condition and load condition have obvious influence on the mechanical characteristics of the dredger fill, and the microstructure characteristics of the soil are the essential factors to determine its macroscopic mechanical properties. In order to study the change rule of the mechanical properties of the dredger fill under different consolidation conditions and load conditions and the correlation between the mechanical properties and the microstructure parameters, the creep tests and microstructural tests of the remodeling and filling soft soil in Tianjin Binhai New Area were carried out under different initial consolidation conditions and load effects. The relationship between macro-mechanical parameters and micro-structural parameters is established by using the grey relational degree theory. The test results show that the stability creep plays an active role in increasing the strength of the dredger fill soft soil. The strength of biased consolidation increases faster than that of unbiased consolidation, and the more sufficient the initial consolidation is, the faster the strength growth is. With the increasing creep time, the equivalent diameter, shape ratio and roundness of particles increase, while the number and circumference of particles and voids, the equivalent diameter, shape ratio and roundness of voids decrease. The shear strength index, C and φ, increase with the increasing equivalent diameter, shape ratio and roundness of particles, but decrease with the increasing number and circumference of particles and voids, the equivalent diameter, shape ratio and roundness of voids. Relevance analysis shows that the equivalent diameter and roundness of particles (pore) are important microstructural parameters that affect the evolution of mechanical properties of the dredger fill. The more sufficient consolidation and creep the dredger fill has, the more stable the adjustment of microstructural parameters is and the higher the strength is.
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