【摘要】 通过岩石的物理力学测试、偏光显微镜以及粉晶X射线衍射等手段测定湘西白垩系红砂岩的基本物理指标和单轴抗压强度、矿物成分、颗粒面积比、堆积密度和颗粒接触率。对红砂岩进行粒度分析,得出其平均粒径和概率累计曲线。分别在烘干、天然和饱和状态对不同岩性的红砂岩进行单轴压缩试验,研究其浸水软化机制,并探讨红砂岩的基本物理指标和微结构参数对其强度和软化系数的影响。研究结果表明:红砂岩单轴抗压强度与孔隙度、饱和吸水率呈指数负相关,与干密度呈指数正相关,与颗粒面积比、堆积密度和颗粒接触率呈线性正相关,而平均粒径对其影响不大。当黏土矿物含量>25%时,单轴抗压强度和软化系数随着黏土矿物含量的增大而减小。通过多元回归分析,得出颗粒面积比和饱和吸水率是影响单轴抗压强度的显著变量,并建立其与红砂岩单轴抗压强度和软化系数相应的二元回归方程。更多还原

【Abstract】 Some experiments are conducted including measuring basic physical indices and uniaxial compressive strength(UCS),mineral composition,grain area ratio(GAR),packing density(PD),and grain contact(GC) of cretaceous red sandstone from Western Hunan by physico-mechanics tests through polarized microscope analysis, and powder X-ray diffraction analysis. The average grain diameter and cumulative relative curve of red sandstone are obtained by the grain size analysis. In order to analyze the wetting soften mechanism of sandstone,the uniaxial compressive tests of different red sandstone samples are conducted under the dry state,the nature state and the saturation state. Additionally,how the basic physical indices and microstructure parameters impact the UCS and strength reduction(SR) due to wetting is investigated. Experimental results indicate that the UCS shows a negative exponential relationship with porosity and saturated water adsorption,but a positive exponential relationship with dry density,and a positive linear relationship with GAR,PD,and GC. However,the average grain diameter has no obvious influence on the UCS of red sandstone. When the clay content is higher than 25%,the UCS and SR decrease with the increase of the clay content. Among multifactorial regression analysis,the GAR and saturated water absorption are found to be the key parameters. As a result,the regression equations of UCS and SR due to wetting,in terms of GAR and saturated water absorption,are proposed.更多还原