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针对湿陷性黄土地区工程建设中常常遇到“渗透-湿陷-渗透”这一反复发生的复杂过程所带来的一系列工程问题,开展了黄土湿陷后渗透性试验研究。基于室内湿陷渗透试验,结合扫描电子显微镜(SEM)和图像处理软件(IPP)分析等手段,通过试验对比研究了黄土湿陷前后土体的渗透系数、微结构、孔隙大小分布、孔隙形状及连通性的变化,以揭示黄土湿陷对其渗透性的影响规律及其微观机理。结果表明:渗透过程和湿陷过程相互影响,黄土的多孔结构是影响渗透性及湿陷性的主要内因;湿陷后黄土较原状黄土的渗透性明显变差,原状黄土多孔结构遭到破坏,颗粒接触方式有所变化,使得颗粒排列变密实,且孔隙连通性降低,从而导致渗透系数明显下降(为原状黄土的25%~33%);土的结构和构造、可溶盐的溶解和土中胶结物的溃散、土中孔隙的大小与数量以及连通性变化是黄土湿陷对渗透性影响的重要因素,多因素共同作用使得湿陷后土体渗透系数降低;试验结果可为湿陷性黄土地区的工程设计与施工提供可借鉴的基础理论依据。
For engineering construction in collapsible loess area, a series of engineering problems caused by the recurring complicated process of “infiltration - collapsibility - infiltration ” are often encountered, and the post permeability test of the loess collapses is carried out. Based on the experiment of indoor collapsible penetration test and scanning electron microscope (SEM) and image processing software (IPP), the permeability coefficient, microstructure, pore size distribution, pore shape, Connectivity changes in order to reveal the loess collapsibility impact on permeability and its micro-mechanism. The results show that the infiltration process and the collapsible process influence each other. The porous structure of loess is the main internal factor that affects the permeability and collapsibility. The permeability of loess after collapsible is obviously worse than that of undisturbed loess, the porous structure of undisturbed loess is destroyed, Changes in particle contact patterns result in denser grain arrangement and decreased pore connectivity, resulting in a significant decrease in permeability coefficient (25% to 33% of undisturbed loess); soil structure and structure, soluble salt dissolution and soil The collapsibility of cement, the size and number of pores in the soil, and the change of connectivity are the important factors that affect the permeability of loess collapses. The multi-factor interaction makes the permeability coefficient of the collapsed soil decrease. The test results can be collapsibility Loess area engineering design and construction can provide reference for the basic theoretical basis.