不同含水率条件下拜耳法赤泥强度及水力学特性

Strength and hydraulic characteristics of Bayer red mud under various water contents

在利用XRD、XRF、SEM等微观测试手段分析了拜耳法赤泥的化学成分、矿物组成和微观结构的基础上,通过无侧限抗压强度实验、固结排水三轴剪切实验研究了拜耳法赤泥在不同水力路径条件下其强度特性的变化规律;同时通过非饱和土瞬态水力特性循环实验系统对拜耳法赤泥的水力学特性进行了研究。研究表明:含水率的变化对拜耳法赤泥的强度特性有较大程度的影响,在脱水干燥过程中,其抗压强度和抗剪强度指标均有较大程度的增长;拜耳法赤泥具有遇水崩解现象,已干燥硬化的赤泥会遇水崩解,强度指标明显降低,且在较低应变处即发生脆性破坏;拜耳法赤泥的土-水特征曲线和渗透系数特征曲线均展现出明显的滞后效应,说明拜耳法赤泥对水有较大的敏感性,在降雨条件影响下,拜耳法赤泥堆体的稳定性有一定程度的降低。

The chemical components,mineral composition,and microstructure of Bayer red mud were analyzed by micro-measurements,such as X-ray diffraction（ XRD）,X-ray fluorescence（ XRF）,and a scanning electron microscope（ SEM）. On this basis,the mechanical properties of Bayer red mud with various hydraulic histories were studied with an unconfined compression strength test and a triaxial consolidated drained shear test.Meanwhile,the hydraulic characteristics were also studied by a transient hydraulic characteristic cyclic test of unsaturated mud. The test indicated that the changes in water content had significant effects on the strength characteristics of Bayer red mud. Its compressive strength and shear strength both largely increased during the dehydration process. The strength of Bayer red mud clearly decreased and brittle failure occurred with low strain in water. For example,the dried and hardened red mud disintegrated in water. The soil-water characteristic curve（ SWCC） and HCFC of the Bayer red mud demonstrated that the Bayer red mud is sensitive to water because there is a clear hysteresis effect. Thus,the stability of the Bayer red mud stack is reduced at a certain degree by rainfall.