掺砂红土的力学特性及掺砂机理研究

Research on mechanical properties and sand-doped mechanism of the laterite improved with sand

通过对不同掺砂比例的红土进行液塑限、击实、无侧限抗压强度、直剪和扫描电镜等试验的对比研究,明确了不同掺砂比例对红土的含水性、击实性、强度等力学特性以及微结构特征的影响。试验结果表明:红土掺砂后,可以显著降低红土的液塑限、塑性指数和最优含水率,提高最大干密度、无侧限抗压强度和抗剪强度。随着掺砂比例的增加,掺砂红土的液塑限、塑性指数和最优含水率逐渐降低,最大干密度、无侧限抗压强度和抗剪强度逐渐增大,但强度的增大存在一个合理的掺砂比例。红土的掺砂机理可以结合掺砂红土的数码照片和微结构图像,从掺砂红土所具有的团粒化作用、填充作用、摩擦作用、联损作用及减水作用等五个方面来解释,掺砂红土力学特性的变化正是这五个方面综合作用的结果。

Based on the comparison study of the tests such as Atterberg limits tests,compaction tests,unconfined compression tests,direct shear tests and SEM tests on the mixtures of laterite and sand with different mixing ratios,the influences of different sand-doped ratios to the water features,compaction behaviors,strength properties and micro-structural characteristics of laterite are analyzed.The testing results indicate that after the sand with different mixing ratios is added to laterite,the liquid limit,plastic limit,plasticity index and optimum moisture content of the laterite are decreased significantly,and the maximum dry density,unconfined compression strength and shear strength of the laterite are increased.With the increase in the proportion of the mixed sand,the liquid limit,plastic limit,plasticity index and optimum moisture content of the laterite are reducing gradually,and the maximum dry density,unconfined compressive strength and shear strength of the laterite are growing gradually,but there is a reasonable sand-doped ratio for the increase of strength.Based on the digital photos and micro-structure images,the sand-doped mechanism of laterite could be explained from the five aspects such as the aggregation,filling,friction,join-losing and water-reducing,and the variation of the mechanical properties for the laterite mixed with sand is the result of the combination of the five aspects.