| 黄豆脲酶诱导碳酸钙沉淀多变量试验研究 |
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| 引用本文： | 崔猛,符晓,郑俊杰,吕苏颖,熊辉辉,曾晨,韩尚宇.黄豆脲酶诱导碳酸钙沉淀多变量试验研究[J].岩土力学,2022,43(11):3027-3035. |
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| 作者姓名： | 崔猛 符晓 郑俊杰 吕苏颖 熊辉辉 曾晨 韩尚宇 |
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| 作者单位： | 1. 南昌工程学院 土木与建筑工程学院，江西 南昌 330099；2. 江西省水利土木特种加固与安全监控工程研究中心，江西 南昌 330099；
3. 华中科技大学 土木与水利工程学院，湖北 武汉 430074；4. 南昌航空大学 土木建筑学院，江西 南昌 330063 |
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| 基金项目： | 国家自然科学基金项目（No.52268059，No. 51609114）；江西省教育厅基金项目（No. GJJ19094）。 |
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| 摘 要： | 植物源脲酶诱导碳酸钙沉淀（enzyme induced carbonate precipitation，简称EICP）可以显著改善砂土的工程力学特性，但在具体操作时，参数取值无对应规范，固化效果有待提升。基于黄豆脲酶，研究了温度、脲酶浓度、尿素浓度、钙浓度、pH值、钙源种类等变量对脲酶活性与碳酸钙沉淀的影响，并进行了沉淀物（碳酸钙晶体）的扫描式电子显微镜（scanning electron microscope，简称SEM）与X射线衍射（X-ray diffraction，简称XRD）测试，在此基础上开展了黄豆脲酶固化砂的无侧限抗压强度与固化效果试验研究。结果表明：脲酶活性随脲酶浓度的增加而线性增长，但存在温度阈值，温度超过阈值后，脲酶将完全失活，且阈值随脲酶浓度的增大而降低；尿素浓度与pH值共同影响脲酶活性，二者存在一个最优组合，当尿素浓度在0.1～1.0 mol/L时最优pH值为7，当尿素浓度在1.0～1.5 mol/L时最优pH值为8。脲酶是沉淀反应的催化剂，脲酶浓度越高，反应越完全，碳酸钙沉淀率越高；尿素与钙溶液则主要通过掺入量影响碳酸钙沉淀量，掺量比例宜为1:1，且二者浓度与pH值可通过影响脲酶活性来影响碳酸钙的沉淀情况；不同钙源对碳酸钙沉淀量的影响幅度不大。不同钙源沉淀碳酸钙晶体的成分与密度基本相同，但晶体结构差异较大，氯化钙沉淀碳酸钙晶体以块状为主，表面分布球状、类球状晶体，胶结面大，可作为EICP技术中较为理想的钙源。基于黄豆脲酶和氯化钙钙源固化砂的无侧限抗压强度约为掺粉煤灰砂样的6倍，通过SEM图像可发现，沉淀碳酸钙晶体包裹并黏结砂粒成为整体，固化效果非常理想。
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| 关 键 词： | 黄豆脲酶 脲酶活性 碳酸钙沉淀 固化砂 试验研究 |
| 收稿时间： | 2021-12-23 |
| 修稿时间： | 2022-07-13 |
Multivariate experimental study on soybean urease induced
calcium carbonate precipitation |
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| CUI Meng,FU Xiao,ZHENG Jun-jie,LÜ Su-ying,XIONG Hui-hui,ZENG Chen,HAN Shang-yu.Multivariate experimental study on soybean urease induced
calcium carbonate precipitation[J].Rock and Soil Mechanics,2022,43(11):3027-3035. |
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| Authors: | CUI Meng FU Xiao ZHENG Jun-jie LÜ Su-ying XIONG Hui-hui ZENG Chen HAN Shang-yu |
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| Institution: | 1. School of Civil and Architectural Engineering, Nanchang Institute of Technology, Nanchang, Jiangxi 330099, China;
2. Jiangxi Province Key Laboratory of Hydraulic & Civil Engineering Infrastructure Security, Nanchang, Jiangxi 330099, China;
3. School of Civil and Hydraulic Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China;
4. College of Civil Architecture, Nanchang Hangkong University, Nanchang, Jiangxi 330063, China |
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| Abstract: | The plant-derived urease-induced calcium carbonate precipitation (EICP) can significantly improve the engineering mechanical properties of sand. However, there is no corresponding specification for the parameter value in the specific operation, and the reinforcement effect needs to be improved. Based on soybean urease, the effects of temperature, urease concentration, urea concentration, calcium concentration, pH, calcium source type and other variables on urease activity and calcium carbonate precipitation were studied, and the tests on SEM and XRD of precipitated calcium carbonate crystals were carried out. On this basis, the unconfined compressive strength and curing effect of soybean urease-cured sand were tested. The results showed that urease activity increased linearly with the increase of urease concentration, but there was a temperature threshold value. When the temperature exceeded the threshold, urease activity was completely inactivated, and the threshold decreased with the increase of urease concentration. Urea concentration and pH affected urease activity together, and there was an optimal combination of them, that is, the optimal pH is 7 when urea concentration is 0.1-1 mol/L, and it is 8 when urea concentration is1.0-1.5 mol/L. Urease is the catalyst of a precipitation reaction. The higher the urease concentration was, the more complete the reaction was, and the higher the precipitation rate of calcium carbonate was. For urea and calcium solution, the dosage mainly affected the precipitation of calcium carbonate, and the dosage ratio should be 1:1. The concentration and pH of urea and calcium solution can affect the precipitation of calcium carbonate by affecting urease activity. Different calcium sources had little influence on the precipitation amount of calcium carbonate. The composition and density of precipitated calcium carbonate crystals from different calcium sources were basically the same, but the crystal structure was very different. The calcium chloride precipitated calcium carbonate crystals are mainly massive, with spherical and spheroidal crystals on the surface and large cementation surface, which can be used as an ideal calcium source in EICP technology. The unconfined compressive strength of the sand solidified with urease from soya beans and calcium chloride as calcium source was about 6 times that of the sand mixed with coal fly ash. SEM images show that the precipitated calcium carbonate crystals wrap and bond the sand into a whole, and the curing effect is ideal. |
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| Keywords: | soybean urease urease activity calcium carbonate precipitation solidified sand experimental study |
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