摘要
为分析浸水对聚氨酯固化砂土的作用,采用核磁共振技术对固化砂土浸水后的微观特性和强度特性进行研究。对添加不同固化剂含量、不同密度和不同浸水时间的固化砂土进行核磁共振和无侧限抗压强度测试。研究结果表明,随着固化剂含量增加,T2谱由单一峰值发展为多个峰值,且幅值面积也持续增加;幅值强度和面积随浸水时间增长而增加;随着固化剂含量和浸水时间的增加,总有效孔隙率增加,且相对大孔喉所占的比例均增加;密度增加,小孔喉所占比例增加,大孔喉减小;随着固化剂含量和浸水时间增加,核磁共振成像图中亮点越多,有效孔隙增加;随着密度增加,核磁共振成像图中亮点由连续集中变化为分散状态;强度随浸水时间增加而减小,加入1%固化剂强度在浸水24 h前最高,大于2%后,浸水后强度随固化剂含量增加而增强。密度增加,浸水后强度保持增加趋势。通过核磁共振技术测试了固化砂土的微观变化规律,揭示了浸水对聚氨酯固化砂土微观特性的影响和以及宏观强度特性的微观作用机制。
In order to analyze the effect of immersion on polyurethane-solidified sand,the micro and strength characteristics of reinforced sand after immersion are tested by NMR and unconfined compression tests.The results show that with the increase of curing agent content,T2 spectra develop from a single peak to multiple peaks,and the amplitude area continues to increase.The amplitude intensity and area increase with the increase of immersion time.With the increase of curing agent content and immersion time,the total effective porosity increases,and the proportion of pore throat increases.With the increase of density,the proportion of small pore throat increases,and the proportion of big pore throat decreases.With the increase of curing agent content and immersion time,the more the bright spots in the NMR image of the sample section,the more the effective pores.With the increase of the density,the bright spots in the NMR image change from continuous concentration to non-dispersive state,and the macropores in the sample decrease and the micropores increase;and the strength decreases with the increase of immersion time.The strength of reinforced sand with curing agent of 1%is the highest before immersion for 24 h.When the content of curing agent is more than 2%,the strength increases with the increase of the content of curing agent.With the increase of density,the strength keeps increasing after immersion.The microcosmic variation of solidified sand soil is tested by NMR.The influences of water immersion on the microcosmic properties of polyurethane reinforced sand and the microcosmic mechanism of the macroscopic strength properties are revealed.
作者
王颖
刘瑾
马晓凡
祁长青
卢洪宁
WANG Ying;LIU Jin;MA Xiao-fan;QI Chang-qing;LU Hong-ning(School of Earth Sciences and Engineering,Hohai University,Nanjing 211000,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2020年第12期2342-2349,共8页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金面上项目(41877212)。
关键词
固化砂土
浸水
低场核磁共振
微观特征
成像分析
solidified sand
immersion
low-field NMR
microscopic characteristic
imaging analysis
