干湿循环作用下地聚物固化黄土的劣化性研究  

Study on the Deterioration of Geopolymer Solidified Loess under Dry-Wet Cycles Effect

作　　者：李昊杰 唐先习[1] 张徐军 李明泽 王之鲁 Li Haojie;Tang Xianxi;Zhang Xujun;Li Mingze;Wang Zhilu(School of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,P.R.China;China Railway Lanzhou Group Co.,Ltd.,Lanzhou 730000,P.R.China)

机构地区：[1]兰州理工大学土木工程学院,兰州730050 [2]中国铁路兰州局集团有限公司,兰州730000

出　　处：《地下空间与工程学报》2025年第2期506-516,共11页Chinese Journal of Underground Space and Engineering

基　　金：国家自然基金项目(11962016);中国铁路兰州局集团有限公司资助项目(LTKY2023036-1)。

摘　　要：近年来,极端天气频繁发生,加上人类活动加剧,导致西北地区地下水位波动频繁,对固化土产生了较大影响。本文以粉煤灰和钢渣为原料,通过碱性硅酸钠溶液激发形成一种较高强度地聚物凝胶材料固化黄土,通过无侧限抗压强度试验、直剪试验、电子显微镜扫描试验(SEM)和X射线衍射试验(XRD),研究干湿循环后的固化土力学性能以及微观结构的变化。结果表明:干湿循环湿化度是固化土劣化的一个重要因素,随着湿化度增加,固化土的劣化程度增加;同时,添加地聚物可以有效减缓固化土的劣化程度,固化土黏聚力随着循环次数的增加呈线性持续劣化趋势,掺量为20%的聚合物固化土具有较好的抗干湿稳定性;经过15次循环后,素土和固化土的内摩擦角在前7次干湿循环中均有所减小,但在第7次之后变化趋势平缓;通过SEM和XRD分析观察到,在干湿循环的初期,固化土中存在少量未反应的钢渣和粉煤灰,这些物质在继续水化反应后形成了C-S-H和C-A-S-H胶凝物质,填充了土颗粒之间的空隙,减缓了固化过程的劣化程度。In recent years,the frequent occurrence of extreme weather conditions,coupled with intensified human activities,has led to frequent fluctuations in groundwater levels in the northwest region,exerting significant impacts on stabilized soils.This paper explores the utilization of fly ash and steel slag as raw materials,activated by an alkaline sodium silicate solution,to form a high-strength geopolymer gel material for the stabilization of loess soil.Through unconfined compressive strength tests,direct shear tests,scanning electron microscopy(SEM)examinations,and X-ray diffraction(XRD)analyses,the mechanical properties and microstructure changes of the stabilized soil after wet-dry cycles were investigated.The results indicate that:The degree of wetness during wet-dry cycles is a crucial factor contributing to the degradation of stabilized soil,with an increase in degradation observed as the wetness level rises.Notably,the incorporation of geopolymers effectively mitigates this degradation process.The cohesion of the stabilized soil exhibits a linear and continuous deterioration with an increasing number of cycles.A geopolymer-stabilized soil with a 20% additive content demonstrates superior resistance to wet-dry stability.After 15 cycles,both the internal friction angle of the untreated soil and the stabilized soil decrease within the first 7 wet-dry cycles but show a flattened trend subsequently.SEM and XRD analyses reveal that,in the early stages of wet-dry cycling,a small amount of unreacted steel slag and fly ash are present in the stabilized soil.These materials undergo further hydration reactions to form C-S-H and C-A-S-H cementitious compounds,which fill the voids between soil particles and thereby reduce the extent of degradation during the stabilization process.

关 键 词：固化黄土 干湿循环 地聚物 钢渣粉 劣化性 

分 类 号：TU444[建筑科学—岩土工程]