纳米硅溶胶加固粉质砂土的性能研究

Study on the Properties of Nano-Silica Sol for Strengthening Silty Sand

摘要:

粉质砂土具有富含微细孔隙的特点，导致对其进行注浆加固较为困难。在传统注浆加固材料的基础上，引入纳米硅溶胶，研究纳米硅溶胶对粉质砂土加固的影响。以纳米硅溶胶加固粉质砂土为研究对象，通过注浆效果对比试验、无侧限抗压强度实验、渗透实验、SEM扫描电镜分析等试验方法，比较不同养护环境及龄期加固土力学性能。结果表明：纳米硅溶胶注浆性能相对与传统注浆材料能快速有效地渗入土体对土粒进行胶结，对孔隙进行封堵。通过设置干燥空气和水两种养护环境养护后进行相应力学试验及抗渗冲刷试验，结果发现：当填充率为25%时，纳米硅溶胶加固土强度最大可提高至280—290 kPa，连续水流冲刷下抗渗时间扩展至340 h。此外，比较不同养护环境及龄期的加固土组成成分及结构特征发现，水养护下加固土结构更为完整，孔隙更少。因此，纳米硅溶胶在富水地区对加固粉质砂土具有更大的优势。

关键词:富水粉砂层;物理力学性质;注浆加固;纳米硅溶胶

Abstract:

Silty sand has the characteristic of being rich in micro pores， which makes it more difficult to reinforce it by grouting. Based on the traditional grouting reinforcement material， nano-silica sol was introduced to analyze the feasibility for reinforcement of silty sand. In this paper， the physical and mechanical properties of reinforced soil under different conditions were compared by using laboratory test methods such as comparative test of grouting effect of different materials， unconfined compression strength experiment， permeation experiment and SEM scanning electron microscope analysis. The results showed that the nano-silica sol grouting can quickly and effectively penetrate into the soil to cement the soil particles and seal the pores compared with traditional grouting materials. After the curing in both dry air and water environments， the mechanical experiments and seepage scouring experiments were carried out. When the filling rate was 25%， the strength of nano-silica sol reinforced soil increased to 280—290 kPa， and the seepage resistance time was extended to 340 h under continuous water scouring. By comparing the compositions and structural characteristics of reinforced soils in different curing environments and ages， it found that the structure of reinforced soils was more complete and less porous under water curing， so the nano-silica sol had a greater advantage in water-rich areas.

Key words:water-rich sand layer;physical and mechanical properties;grouting reinforcement;nano-silica sol