Dynamic stress and microanalyses of the cement-soil modified by nano-SiO2 in the seawater corrosive environment
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摘要:
为研究纳米SiO2改良水泥土抵抗动力荷载-海水腐蚀耦合作用效果，通过动三轴、扫描电镜（SEM）、核磁共振试验（NMR），获取不同海盐溶液浓度和时间下动应力参数及NMR曲线图、SEM图，探究海盐溶液浓度和腐蚀天数对改良前后水泥土的影响。试验结果表明：改良土内部孔隙减少，土颗粒间胶结度提高，土体抵抗动力荷载-海水腐蚀耦合作用能力增强，清水环境下，养护7，14，28 d改良水泥土动强度分别提高了4.8%、6.6%、7.3%；经海水腐蚀后，土体内部结构遭到破坏，土颗粒松动且孔隙增多，水泥土动强度明显下降，腐蚀28 d、清水、1倍、2倍、3倍海水浓度溶液环境下，纳米水泥土相对于普通水泥土动强度分别提高了9.4%、7.3%、6.6%、6.3%。
Abstract:In order to study the coupling effect of nano-SiO2 modified cement soil against dynamic load and seawater corrosion, dynamic stress parameters, NMR curves and SEM diagrams under different sea salt solution concentrations and times are obtained through the dynamic triaxial, scanning electron microscope and nuclear magnetic resonance tests to explore the effects of sea salt solution concentrations and corrosion days on the cement soil before and after improvement. The test results show that the internal pores of the improved soil are reduced, the cementation between the soil particles is improved, and the soil's ability to resist the coupling action of dynamic load and seawater corrosion is enhanced. Under the clear water environment, the dynamic strength of the improved cement soil after curing for 7, 14 and 28 days is increased by 4.8%, 6.6% and 7.3%, respectively. After sea water corrosion, the internal structure of soil is damaged, soil particles become loose and pores increased, and the dynamic strength of the cement soil decreases significantly. After 28 days of corrosion, the dynamic strength of the nano cement soil is increased by 9.4%, 7.3%, 6.6% and 6.3%, respectively, compared with the ordinary cement soil under the environment of clean water, double and triple seawater concentration solution.
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Key words:
- nano-SiO2 /
- cement soil /
- dynamic triaxial /
- dynamic strength /
- corrosive environment
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表 1 试验用土基本物理指标
Table 1. Properties of the tested soil
密度/
（g∙cm−3）比重 孔隙
比液限/
%塑限/
%塑性
指数压缩系数/
（MPa−1）1.6 2.68 1.15 39.44 19.45 19.99 1.45 
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表 2 纳米SiO2的主要性能指标
Table 2. Properties of nano silicon powder
粒径
/nm比表面积
/（m2∙g−1）表面羟
基/%摇实密度
/（g∙cm−3）松装密度
/（g∙cm−3）sio2−x含
量/%密度
/（g∙cm−3）10±5 640±50 48 <0.22 <0.15 >99.9 2.44
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表 3 试验配比方案
Table 3. Test matching scheme
水泥掺量(m水泥/m湿土×100%） 15% 纳米SiO2掺量（aw＝ 
/m湿土×100%）0%，2.5% 水灰比（w/c=m水 /( 
+ m水泥)）0.45 海盐浓度/（g·L−1） 0，35，70，105
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