冻融作用下全风化千枚岩力学性质研究

Study on the mechanism of weathered phyllite under freezing and thawing conditions

选取山区全风化千枚岩滑带土为研究对象,实验条件下对其进行全矿物X射线衍射分析测试以及经历不同次数冻融循环作用后全风化千枚岩滑带土的抗剪强度、单轴抗压强度的测试,对全风化千枚岩滑带土在水-低温作用下抗剪强度和单轴抗压强度等相关指标的变化进行了研究,揭示了全风化千枚岩滑带土在水-低温作用下相关指标的劣化规律,并初步探讨其劣化机理.结果表明,在多次冻融作用下,云母、方解石、长石、黄铁矿等矿物的溶蚀,石膏与伊利石、伊蒙混层等次生黏土矿物的生成及其吸水膨胀与失水收缩,使滑带土孔隙增大,是全风化千枚岩滑带土在冻融条件下物理、力学性能的主要原因;冻融前期黄铁矿在湿润条件下极易氧化并产生强酸,加速溶蚀并腐蚀其他矿物,致使全风化滑带土冻融前期力学性能劣化速率远大于后期.

The fully weathered phylite rock-slip belt soil in the mountainous area was selected as the research object.Experimental conditions were provided for a mineral X-ray diffraction analysis and different number of freeze-thaw cycle effects after fully weathered phyllite were experienced;the shear strength of sliding zone,uniaxial compressive strength test,the weathered phyllite sliding zone soil under the action of water and low temperature shear strength,uniaxial compressive strength and the correlative indexes of change were all studied,the degradation law of related indexes of the fully weathered rock slip zone soil under water-low temperature action was explored and its degradation mechanism preliminarily discussed.The results showed that,under the effect of repeated freeze-thaw,calcite,feldspar,mica,thedissolution of minerals such as pyrite,gypsum and secondary clay minerals such as illite,deceiving layer content generation and its water absorption expansion and water loss contraction,would increase pore sliding zone,which was fully weathered phyllite sliding zone soil under the condition of freezing and thawing of the main causes of physical and mechanical properties.Pyrite was easy to oxidize and produced strong acid under wet conditions in the early freezing-thawing period,which accelerated the dissolution and corrosion of other minerals,thus resulting in a much higher mechanical property degradation rate of soil in the early freezing-thawing period in the fully weathered slip belt than that in the later period.