Strength characteristics and micro-mechanism analysis of solidified high-salt soft soil

SUN Jiancheng; YANG Chen; LIU Junyong; YIN Lihua; ZHANG Chao

doi:10.7688/j.issn.1000-1646.2026.01.15

Abstract：[Objective]In the actual construction of road engineering,it is often difficult for high-salt soft soil to meet the technical requirements of engineering construction directly due to its special physical and mechanical properties.Therefore,a systematic study on the solidification characteristics of high-salt soft soil should be conducted to provide theoretical support and technical references for the reasonable utilization of this type of soft soil in road engineering via an in-depth analysis of various characteristics presented during soft soil solidification.[Methods]Laboratory experiments were combined with theoretical analysis to conduct indoor solidification of high-salt soft soil,and the strength characteristics and micro-mechanism of the solidified soft soil were studied.Meanwhile,the cement single-mixing tests and the three-factor,three-level orthogonal tests of cement,lime and fly ash were set up,respectively.By focusing on the two types of tests,the effects of salt contents of 1.5%,3.5%,5.5%,and 7.5%on the unconfined compression strength of high-salt solidified soft soil were explored.Then,the X-ray diffractometer(XRD)and scanning electron microscope(SEM)were adopted to further investigate the micro-mechanism of the solidified high-salt soft soil,and thus gain a deeper understanding of the mechanism.[Results]The cement single-mixing test shows that under the constant initial water content and salt content of soft soil,there is optimal mixing content for cement solidification of high-salt soft soil.Additionally,by setting different mixing contents of cement,lime,and fly ash for composite solidification treatment of soft soil with salt content of 7.5%,the maximum unconfined compression strength of the samples after 7,14,and 28 days of curing can reach 326 kPa,388 kPa,and 593 kPa,respectively,which can better meet the construction needs of actual projects.[Conclusions]When the combination of 7%cement+3%fly ash+3%lime is employed as the inorganic gelling solidification agent,the relatively ideal solidification effect can be achieved for soft soil with different salt contents.It should be noted that under the premise of keeping the mix ratio of the solidification agent unchanged,the strength of the solidified soft soil shows a trend of continuous deterioration with the gradually increasing salt content in the soft soil.Additionally,the effect of chlorine salt on the strength of solidified soft soil becomes increasingly significant with the rising curing age.