有机质对软土流变性质影响的试验研究

采用人工土、自然土、半人工半自然土制备3组有机质含量不同的试样,测试其基本的物理力学特性。采用改进的直剪蠕变仪,用分级加载的试验方法在相同试验条件下对所制备试样的流变性质进行测试,得到各试样在各级荷载下的蠕变曲线,进而求得各试样的平均粘滞系数。对各组试样的粘滞系数进行对比分析,结果表明有机质及其含量是影响软土流变性质的重要因素之一,土体的粘滞系数随有机质含量的增加而减小,即流变变形阻力随有机质含量的增多而减小。试验结果分析认为,有机质通过吸附于土颗粒表面的结合水影响土的流变性质,其中强结合水是土体产生流变的主要因素,而弱结合水则是相对次要因素。文中的试验结果有助于进一步认清土体流变的起因,对改进和完善现有流变变形计算理论有一定指导意义。

Experiment Study of the Effects of Organic Matter on the Rheological Characteristics of Soft Soils

Three groups of soft soil samples made of artificial soil and natural soil with different contents of organic matter were prepared, and the geotechnical index properties determined. Utilizing an improved direct shear creep apparatus, the rheological characteristics of the soil samples were tested under stepwise loading with same test conditions. The strain-time curves under different loads were obtained from the tests, and the average viscosity coefficients of the soil samples were calculated according to the curves. Comparative analyses of the average viscosity coefficients of the soil samples of each group show that organic matter and its content are important factors on the creep behavior of soft soil, with the viscosity coefficient decreasing as the organic matter content increases, which implies that creep strain resistance decreases with increase in the organic matter content. It is concluded that organic matter affects soft soil rheological characteristics by means of water bonding the soil particle surface, furthermore, strong adhesive water is a key factor while weak adhesive water only secondary.