冻融循环作用下水泥固化淤泥质土的强度劣化试验研究

Experimental study on compressive strength of cement solidified soft clay by freeze-thaw cycles

针对淤泥质土的不良工程特性,考虑冻融循环作用对固化淤泥质土强度的影响及作用规律,以安徽省青弋江流域淤泥质土为研究对象,开展了不同水泥掺比、不同冻融环次数的固化淤泥质土无侧限抗压强度试验,对比分析了在60 d养护龄期条件下,水泥掺量、冻融循环次数对淤泥质土固化强度的弱化规律,并探讨了淤泥介质结构损伤影响因素,为淤泥质土在堤坝工程中资源化利用积累研究经验。试验结果表明:固化淤泥质土在冻融循环过程中产生吸湿—冻胀效应,不同水泥掺比的试样质量差异显著;随着冻融循环次数的增加,其无侧限抗压强度成非线性关系降低,在第9次循环结束后抗压强度趋于稳定,10%、15%和20%水泥掺比下的固化土的无侧限抗压强度基本稳定在1.3 MPa、1.7 MPa和2.3 MPa。

In view of the undesirable engineering characteristics of soft clay,considering the influence of freeze-thaw cycle on the strength of solidified soft clay,we studied the soft clay in Qingyijiang and carried out the unconfined compressive strength test of solidified soft clay with different cement mixing ratio and different times of dry freeze-thaw cycles.It is analyzed influencing factors of strength weakening on solidified soft clay with the condition of 60 d curing age.In addition,the internal damage mechanism and influencing factors of soft clay structure are discussed,which can accumulate research experience for the utilization of soft clay in the dam engineering.The test proves that the solidification of silty soil results in hygroscopic and frost heaving effect during freezing-thawing cycles,and the quality of the samples with different cement ratios is significantly different.With the increase of freeze-thaw cycle times,the unconfined compressive strength decreases in a nonlinear relationship and the trend was stable after the end of the 9 th cycle.The unconfined compressive strength of solidified clay with 10%,15%and 20%cement is basically stable at 1.3 MPa,1.7 MPa and 2.3 MPa.