含腐殖酸软土的固化试验研究

Experimental study on stabilization of humus-containing soft soil

深层搅拌法在加固含有腐殖酸的软土时失去了效用,需要添加促进剂来消除腐殖酸的影响.在去除有机质的黏质粉土中加入腐殖酸,研究了经某种液态添加剂改良后的水泥土特性.结果表明,添加剂消除胡敏酸影响的效果最显著,腐殖酸次之;添加剂在水泥质量分数大于10%时才表现出明显的增强效果,在水泥质量分数不变的情况下,仅提高添加剂的质量分数,固化土强度的增幅较小,添加剂相对于水泥的质量分数取0.15%为宜;当水与水泥质量比从0.45提高到0.75时,固化土的强度逐渐降低,但与水泥土相比,水与水泥质量比对固化土强度的影响较小;固化土的后期强度增长明显大于水泥土,当采用该种水泥土添加剂进行工程设计时,可适当考虑后期强度的增长.

Deep mixing method for soft soil is ineffective while humus content is above a certain value, thus additives should be mixed into cemented soil to eliminate the influence. Humus was added into nonorganic silt to clarify the effect of a variety of additives on the cemented soil performance. The additive is effective to treat the silts containing humic acid, fulvic acid and both of the two acids, especially the humic acid; while using the additive, cement mixing ratio should be higher than 10% and the mass ratio of additive to cement should be about 0.15%, increase of additive mixing ratio doesn＇t help much when cement mixing ratio keeps constant; strength of the stabilized soil is gradually decreased while the mass ratio of water to cement increases from 0.45 to 0.75, but the effect of the ratio is not as dramatic as cemented soil; the long time strength of stabilized soil is much higher than that of the cemented soil, which can be taken into account in the design of deep mixing foundation.