基于微生物矿化作用的砂土加固实验研究
时间:2018-08-02 20:17 来源:毕业论文 作者:毕业论文 点击:次
| 摘要：随着经济规模的飞速发展，人口数量的高速增长，对基础设施建设的需求越来越大。在基础设施的建设过程中，难免会遇到一些软弱土体，不能满足相应的工程需求。与传统的化学材料不同，本文提出利用微生物诱导碳酸钙沉淀（MICP）这一生物矿化过程用于加固砂土，即通过向砂土中添加微生物菌液、尿素、钙离子以及营养物质，利用微生物矿化作用在砂土颗粒间快速沉淀出方解石沉淀，对土体进行胶结，从而改善土体的强度。与传统技术相比，MICP技术具有效果好、耗能低和环境友好等特点。通过试验证明在理论基础上，利用微生物固化砂土具有较好的应用意义与发展前景。主要研究内容和成果如下：（1）巴氏芽孢八叠球菌的培养及脲酶活性研究。巴氏芽孢八叠球菌的脲酶活性以及生长均与温度及pH有着紧密的关系，脲酶活性和生长分别在30℃和环境pH=8时达到最大值，该结论为后续的胶结试验提供了试验参数。（2）砂土颗粒大小与孔隙会直接影响MICP过程中碳酸钙在样品中的空间分布形态及颗粒间孔隙填充密实度，因此较小的颗粒大小以及孔隙利于MICP的效果。另外，胶结液浓度在0.5M时可以向巴氏芽孢八叠球菌提供充足的钙离子及尿素，形成胶结效果好、力学性质好的样品。而针对于样品掺入聚丙烯纤文则可以明显减少样品的脆性。26631 毕业论文关键词：加固砂土;微生物诱导碳酸钙沉淀（MICP）;砂土 Experimental Study on Sandy Soil Improvement using Microbial Induced Calcite Precipitation (MICP) Abstract：With rapid development of economy global and increase of global population, demand for infrastructure construction continues to expand. During the large-scale construction of municipal infrastructure, it is hard to avoid to encountered some weak soil which can not meet the corresponding engineering requirements. Unlike traditional cementing materials, this paper studied on microbial induced calcite precipitation (MICP) to improve soil consolidation ability, injecting bacteria solution and urea, Ca2+ and nutrient broth into loose sand in order to bind soil particles together by CaCO3 and improve physic-mechanical properties, MICP is an effective and environmental friendly soil improvement method compared with traditional methods. This paper shows data which based on scientific basis show that it will be a broad engineering application future in soil improvement. The study results were listed as follows:(1) Firstly, this paper focuses on the bacterial (Sporosarcina pasteurii) culture and its urease activity which affected by temperature and pH. The optimum conditions for Sporosarcina pasteurii growth and its urease activity are 30℃,pH=9, which provides suitable parameters for the following experiments.(2) Secondly, different ranges of particle size and porosity will directly affect MICP process. The pore space of sand with smaller particle size can be tightly filled and a higher proportion of effective calcite crystals can be obtained. Hence, the bio-cemented sand is able to present a higher strength due to the stronger structure established by the calcite crystal clusters. In addition, when the concentration of cementation solution is 0.5M, it gives enough Ca2+ and urea for MICP to enhance sandy soil improvement effect. The effect of randomly distributed discrete fiber on the mechanical properties of MICP-treated sandy soil is to decrease the brittleness of specimens. Key words: soil improvement; microbial microbial induced carbonate precipitation; sandy soil 目 录 摘要1 关键词1 Abstract1 Key words2 引言3 1试验材料与方法3 1.1试验材料3 1.1.1试验用微生物3 1.1.2试验用砂3 1.1.3胶结液3 1.1.4试验所用模具4 1.2试验方法 4 1.2.1微生物数量检测4 1.2.2微生物活性检测4 (责任编辑：qin) |