反压饱和条件下泥炭土B值变化特征研究

泥炭土是一种富含有机质的特殊软土，有机质的降解会在土中形成气体，从而影响泥炭土的饱和度。Skempton孔压系数B常被作为土体的饱和度的衡量标准，针对昆明湖沼相泥炭土，进行了不同反压条件下的三轴饱和试验，得到了相应的B值。试验结果表明:反压为100 kPa时，试样的B值为0.95左右，当反压增加到250 kPa，B值大于0.98，说明泥炭土要达到完全饱和需要较高的反压条件，简单的假设水位线以下土体为完全饱和可能并不合理，在进行土的压缩变形等计算时有必要考虑非饱和性。

Study on B Value Variation Characteristics of Peat Soil under Back Pressure Saturation

Peat soil, a special type of soft soil, contains organic matters which will decompose and form gases in the soil, and the saturation level is thereby influenced. Skempton pore pressure coefficient B is often used as the benchmark for the saturation of soil mass. For the limnetic peat soil at Kunming Lake, triaxial saturation tests under different back pressures were carried out to obtain the corresponding B values. The test result showed that the B value of specimen is about 0.95 when the back pressure is 100 kPa, and more than 0.98 when the back pressure reaches to 250 kPa. This means that there requires relatively high back pressure if peat soil needs to reach a state of complete saturation; hence the simple assumption that the soil is completely saturated under the water level is probably unreasonable. It is necessary to take nonsatiation into consideration when calculating the compressive deformation of soil.