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| EICP修复三合土预制微裂缝效果试验及机理分析 |
| Experimental Evaluation and Mechanism Analysis of EICP Repair Effect on Pre-existing Microcracks in Loess |
| 投稿时间：2024-03-09 修订日期：2024-03-23 |
| DOI： |
| 中文关键词: 酶诱导碳酸盐沉淀法 三合土 裂缝修复 强度恢复率 超声波 |
| 英文关键词:enzyme-induced carbonate precipitation method loess crack repair strength recovery rate ultrasonic. |
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| 中文摘要: |
| 利用EICP技术修复三合土的预制裂缝,通过无侧向抗压试验、三轴试验及超声波试验手段评价其修复效果,通过分析SEM图像揭示EICP修复三合土裂缝生物酶矿化过程及作用机理,结果表明:经EICP技术修复后的三合土试样无侧限抗压试强度恢复率约60%,三轴试验峰值强度回复率随围压增大而逐渐提高,离散系数随围压增大而逐渐降低；修复后的试样均未出现因注射浆液扩散而导致修复效果的离散性增加的情况,不需要对微小裂缝(≤1.4mm)进行胶结物填充。修复后的三合土试样超声波波形图振幅与周期较均一,波形趋于稳定,波速损失率减小,平均声速标准差σ和离差系数COV较破坏后均有所恢复,表明经EICP技术修复后土样内部缺陷和裂缝得到有效修复。三合土微小裂缝经EICP修复后产生的碳酸钙晶体存在两种成核沉淀位置,沉淀在土体裂缝中碳酸钙晶体填补了土体裂隙,减小了孔隙体积,增加了土样的整体性与密实度；沉淀在土体胶凝颗粒表面的团簇状碳酸钙晶体与三合土胶凝颗粒相互胶结形成了一层致密的晶体结构,两者作用均能提高强度恢复率。酶诱导碳酸盐沉淀法对传统三合土微裂缝修复效果良好,可作为三合土微裂缝修复的一种有效方法。 |
| 英文摘要: |
| The repair effect of precast cracks in loess using EICP technology was evaluated through lateral resistance test, triaxial test, and ultrasonic test. The biomineralization process and mechanism of EICP-repaired loess cracks were revealed by analyzing SEM images. The results showed that the lateral tensile strength recovery rate of the loess samples repaired by EICP technology was about 60%, and the peak strength recovery rate of the triaxial test gradually increased with the increase of confining pressure, while the coefficient of variation decreased. The repaired samples did not show an increase in the dispersion of repair effects due to the diffusion of grout injection, and no filling of small cracks (≤1.4mm) with cementitious material was needed. The ultrasonic waveform amplitude and period of the repaired loess samples were relatively uniform, the waveform tended to be stable, the wave velocity loss rate decreased, and the average sound velocity standard deviation σ and coefficient of variation COV recovered comparing to the damaged samples, indicating that the internal defects and cracks of the soil samples were effectively repaired by EICP technology. Two types of calcium carbonate crystals produced after the EICP repair of loess microcracks were found at different nucleation and precipitation sites. The calcium carbonate crystals deposited in the soil cracks filled the soil fissures, reduced the pore volume, and increased the overall integrity and compaction of the soil samples. The cluster-like calcium carbonate crystals deposited on the surface of the soil cement particles formed a dense crystal structure through mutual bonding, which improved the strength recovery rate. Enzyme induced carbonate precipitation method showed good repair effect on traditional loess microcracks and can be considered as an effective method for repairing loess microcracks. |
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