| MICP胶结液中尿素过量的影响研究? |
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| 引用本文： | 刘志明,孙益成,冯清鹏,彭劼.MICP胶结液中尿素过量的影响研究?[J].防灾减灾工程学报,2020(4):574-580. |
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| 作者姓名： | 刘志明 孙益成 冯清鹏 彭劼 |
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| 作者单位： | 河海大学岩土力学与堤坝工程教育部重点实验室，江苏 南京 210098 |
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| 基金项目： | 国家自然科学基金项目（51578214）资助 |
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| 摘 要： | 分析了研究人员对于胶结液中尿素对MICP影响的不同认识之间存在的分歧,利用水溶液试验及一维砂柱加固试验，对比研究了胶结液中尿素过量（双倍浓度）对MICP的影响。在水溶液和砂柱中，进行了三种氯化钙浓度（0.25 M，0.5 M,1.0 M）条件下尿素过量与否的对比试验。测试对比了水溶液试验过程中NH4+，Ca2+变化规律、砂柱试验中Ca2+消耗，CaCO3生成情况和砂柱无侧限强度等。研究结果表明：(1)水溶液试验中，过量的尿素在反应初期不利于尿素水解与碳酸钙沉积; (2)在砂柱试验中，过量的尿素也对MICP不利，加固后土体强度较低，加固效果较差; (3)砂柱试验中这一现象与注浆方式（间隔12 h直灌式注浆）和较短的胶结液停留时间有关; (4)在水溶液和砂柱两种环境下，低氯化钙浓度（0.25 M）情况下尿素过量对MICP的影响都最为明显。
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| 关 键 词： | MICP 胶结液 尿素过量 直灌式灌浆 |
Study on Influence of Excess Urea in MICP Cementation Solution |
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| LIU Zhiming,SUN Yicheng,FENG Qingpeng,PENG Jie.Study on Influence of Excess Urea in MICP Cementation Solution[J].Journal of Disaster Prevent and Mitigation Eng,2020(4):574-580. |
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| Authors: | LIU Zhiming SUN Yicheng FENG Qingpeng PENG Jie |
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| Affiliation: | Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098 , China |
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| Abstract: | The controversy of researchers on the effect of urea in cementation solution on MICP was analyzed. The effects of excess urea (double concentration) on MICP were compared and studied through a series of aqueous tests and cemented tests on one-dimensional sand column. Comparison tests were carried out on the aqueous solution and the sand column under the condition of three concentrations of CaCl2 (0.25M, 0.5M,1.0M). Changes of NH4+, Ca2+ in the water solution, Ca2+ consumption, CaCO3 formation and compression strength of the sand samples in the sand column tests were compared and analyzed. The results show that: (1) In aqueous test, excess urea has an adverse effect on urea hydrolysis and calcium carbonate deposition at the early stage of the reaction;(2) In sand column test, excess urea is also unfavorable to MICP and leads to lower strength of soil sample; (3) The phenomenon in the sand column test is related to injection method and short retention time of the cement (direct grouting at intervals of 12h); (4) The negative effect of excess urea on MICP under low calcium chloride concentration (0.25M) is most pronounced in both aqueous and sand column environments. |
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