连云港徐圩港区海相软土固化特性及强度劣化机理研究

Solidification characteristics and strength deterioration mechanism of marine soft soil in Xuwei Port,Lianyungang

依托连云港徐圩港区二港池多用途泊位转运区软基处理工程,开展海相软土固化、干湿和冻融循环试验,研究水泥混掺石灰、粉煤灰和石膏固化土的固化特性和强度劣化机理。结果表明:水泥和石灰混掺的固化效果、干湿循环耐久性最优,水泥和粉煤灰次之,水泥和石膏最差;水泥+石灰固化土28 d龄期强度分别为水泥+粉煤灰、水泥+石膏固化土强度的2.3~2.9倍、4.7~7.8倍;经历1次和5次干湿循环后,固化土无侧限抗压强度分别降低了10.0%~51.7%和28.8%~69.9%,表明第1次干湿循环对固化土强度影响最为显著;5次冻融循环后,固化土动弹性模量降幅为56.3%~60.3%,质量损失率为10.9%~14.0%;干湿、冻融循环后,固化土微观结构遭到破坏、土体孔隙增加是其强度降低甚至破坏的主要原因。

Based on the soft soil foundation treatment project of the multi-purpose transfer area in the second harbor basin of Xuwei Port in Lianyungang,we carry out the solidification,dry-wet and freeze-thaw cycle tests of marine soft soil,and study solidification characteristics and strength deterioration mechanism of the marine soft soil solidified by cement together with lime,fly ash and gypsum.The results show that the cement mixed lime has the best solidification effect and durability,followed by cement mixed fly ash,cement mixed gypsum.The unconfined compression strengths of marine soil solidified by cement and lime are about 2.3 to 2.9 times and 4.7 to 7.8 times respectively of soil solidified by cement together with fly ash and gypsum.When the solidified soil subjected to one and five dry-wet cycles,reductions in the strength of solidified soils are 25.0%to 51.7%and 37%to 59.5%respectively.It means that the first dry-wet cycle has the most significant effects on the strength of solidified soil.After five freeze-thaw cycles,reductions in the dynamic elastic modulus and mass of the solidified soil decrease are 56.3%to 60.3%and 10.9%to 14.0%respectively.Dry-wet and freeze-thaw cycles induced strength reduction or even failure of solidified soil is mainly due to damage of microstructure and increase of soil voids.