固化疏浚土宏-微观力学特性室内试验研究

Indoor Test on the Macro-and-microscopic Mechanical Properties of Solidified Dredged Soils

以上海某沿海港域吹填场地的砂土和黏土为试验土料,通过掺入自制固化剂和WK-G1型固化剂在室内制备固化疏浚土试样,采用土力学直剪和压缩试验方法,着重分析了固化剂掺量和养护龄期对固化疏浚土试样抗剪强度与压缩变形特性的影响。此外,利用扫描电镜(Scanning Electron Microscope,SEM)从微观层面分析了固化疏浚土试样的结构特征,采用Image-Pro Plus(IPP)图像处理软件和自编Mat Lab程序,提取和分析与颗粒、孔隙及颗粒表面起伏相关的微观结构分维数,基于分形理论,探讨了固化过程中试样微观结构变化与宏观强度及变形特性的宏微观关联。试验结果表明:无论砂土还是黏土,试样压缩模量和抗剪强度均随固化剂掺量和养护龄期的增加呈现出非线性增长规律,在微观机制上,试样压缩模量和抗剪强度的提升与颗粒平均面积与平均半径的增加密切相关。

In this paper,both the macroscopic and microscopic mechanical properties of solidified dredged soil were experimentally studied. First,the influence of curing agent dosage and curing age on shear strength and compressive deformation behaviors were analyzed through direct shear test and 1-D compression test. The solidified dredged soil samples were prepared by adding self-made curing agent and commercial curing agent WK-G1 into the sandy soil and clay collected from a large hydraulic fill field in Shanghai coastal area. In addition,the variation of the microstructure of soil samples during solidification was analyzed via scanning electron microscopy. Based on the fractal theory,the fractal dimensions related to particle and void sizes,particle and void distributions,and particle surface fluctuation were extracted using image processing software Image-Pro Plus and self-coded Mat Lab program. The relationship between microstructure parameters and macro-mechanical property indices was quantitatively explored.Results suggest that for both sandy soil and clay,the compressive modulus and shear strength increased linearly as curing agent dosage and curing age increased; while in microscopic sense,the growth in compressive modulus and shear strength is closely related with the mean area and mean diameter of particle.