基于MICP法的人工胶结砂力学特性试验研究
发布时间：2019-01-06 11:26
【摘要】：传统土壤改良固化剂或灌浆材料多含有有毒物质。我国工程建筑过程中对其的使用会加重环境污染程度,因此研究新型环境友好的土壤加固技术具有重要的现实意义。微生物诱导碳酸盐沉淀(Microbial Induced Calcite Precipitation,以下简称MICP)作为自然界广泛存在的一种生物诱导矿化现象,其具有机理简单,快速高效,容易控制,环境耐受性好等很多传统方法无法比拟的优势。该技术用于土壤加固,将会带来巨大的环境效益和经济效益。基于MICP法,本文主要以巴氏生孢八叠球菌(Sporosarcina pasteurii)胶结标准砂。试验过程中开展了微生物活化培养保存、X衍射、电镜扫描、固结排水剪切、无侧限抗压剪切及碳酸钙含量化学试验等一系列室内试验,主要研究了营养盐溶液浓度、处理方式以及培养温度对MICP胶结试样物理力学特性的影响,为MICP固化土壤的实际应用提供基础数据。本文的主要研究成果为:(1)营养盐溶液浓度的变化对微生物胶结砂土的物理力学特性有极大的影响。在同等营养盐溶液注液量和反应时间下,胶结试样强度随着营养盐溶液浓度的增加,表现为先增后减趋势——呈凸字形态。(2)MICP胶结试样固结排水剪切均表现为应力软化形态,试验结果表明碳酸钙的沉积对砂样的剪胀性具有抑制作用。同时弹性模量随着MICP胶结试样干密度的增加而增加。(3)营养盐溶液浓度影响试验中,0.5M胶结试样c′、φ′值最大胶结效果最优,依据试验结果及前人研究结论,分析是由于其良好碳酸钙的分布形态以及较高碳酸钙晶体的沉积量。(4)采用高/低浓度营养盐溶液相结合的处理方式胶结标准砂。胶结试样可在较短时间表现较高的强度、碳酸钙含量以及较好的均匀性,较为适用胶结深度浅且强度要求较高的土体,具有较好的工程应用潜力。(5)培养环境温度影响试验结果表明:胶结试样在温度为20℃、30℃、40℃环境下培养时,其碳酸钙含量相差不大;但温度的变化对试样强度及变形模量影响较为明显,随着温度的升高(20-40℃)微生物胶结试样的强度及变形模量表现为先增后减的趋势。依据试验结果分析是由于温度变化致使碳酸钙沉积不同晶型造成胶结效果的差异。
[Abstract]:Traditional soil improvement curing agents or grouting materials contain toxic substances. The use of engineering buildings in China will aggravate the degree of environmental pollution, so it is of great practical significance to study the new environmentally friendly soil reinforcement technology. Microbial induced carbonate precipitation (Microbial Induced Calcite Precipitation,) is a kind of biologically induced mineralization phenomenon which exists widely in nature. Its mechanism is simple, fast and efficient, and it is easy to control. Environmental tolerance and many other traditional methods can not be compared with the advantages. The application of this technology to soil reinforcement will bring great environmental and economic benefits. Based on MICP method, (Sporosarcina pasteurii) cementing standard sand was mainly used in this paper. During the experiment, a series of laboratory experiments were carried out, such as microorganism activation culture preservation, X-ray diffraction, electron microscope scanning, consolidated drainage shear, unconfined compressive shear and calcium carbonate content chemical test, etc. The concentration of nutrient solution was studied. The effects of treatment methods and culture temperature on the physical and mechanical properties of MICP cemented samples provide basic data for the practical application of MICP solidified soil. The main results of this paper are as follows: (1) the change of nutrient solution concentration has great influence on the physical and mechanical properties of microbial cemented sand. Under the same amount of liquid injection and reaction time, the strength of the cemented sample increases with the concentration of the nutrient solution. (2) the consolidation and drainage shear of MICP cemented specimens showed stress softening. The results showed that the deposition of calcium carbonate could inhibit the shear dilatancy of sand samples. At the same time, the modulus of elasticity increases with the increase of dry density of MICP cemented sample. (3) in the experiment of the effect of concentration of nutrient salt solution, the maximum cementing effect of 0.5M cemented sample is the best. According to the test results and previous research conclusions, The analysis is due to the good distribution of calcium carbonate and the high deposition amount of calcium carbonate crystal. (4) the standard sand is cemented by the combination of high / low concentration nutrient solution. The cemented specimen can show higher strength, calcium carbonate content and better homogeneity in a short time, which is more suitable for soil with shallow cementing depth and high strength. (5) the effect of culture environment temperature on the content of calcium carbonate is not significant when the temperature is 20 鈩，
本文编号：2402734
[Abstract]:Traditional soil improvement curing agents or grouting materials contain toxic substances. The use of engineering buildings in China will aggravate the degree of environmental pollution, so it is of great practical significance to study the new environmentally friendly soil reinforcement technology. Microbial induced carbonate precipitation (Microbial Induced Calcite Precipitation,) is a kind of biologically induced mineralization phenomenon which exists widely in nature. Its mechanism is simple, fast and efficient, and it is easy to control. Environmental tolerance and many other traditional methods can not be compared with the advantages. The application of this technology to soil reinforcement will bring great environmental and economic benefits. Based on MICP method, (Sporosarcina pasteurii) cementing standard sand was mainly used in this paper. During the experiment, a series of laboratory experiments were carried out, such as microorganism activation culture preservation, X-ray diffraction, electron microscope scanning, consolidated drainage shear, unconfined compressive shear and calcium carbonate content chemical test, etc. The concentration of nutrient solution was studied. The effects of treatment methods and culture temperature on the physical and mechanical properties of MICP cemented samples provide basic data for the practical application of MICP solidified soil. The main results of this paper are as follows: (1) the change of nutrient solution concentration has great influence on the physical and mechanical properties of microbial cemented sand. Under the same amount of liquid injection and reaction time, the strength of the cemented sample increases with the concentration of the nutrient solution. (2) the consolidation and drainage shear of MICP cemented specimens showed stress softening. The results showed that the deposition of calcium carbonate could inhibit the shear dilatancy of sand samples. At the same time, the modulus of elasticity increases with the increase of dry density of MICP cemented sample. (3) in the experiment of the effect of concentration of nutrient salt solution, the maximum cementing effect of 0.5M cemented sample is the best. According to the test results and previous research conclusions, The analysis is due to the good distribution of calcium carbonate and the high deposition amount of calcium carbonate crystal. (4) the standard sand is cemented by the combination of high / low concentration nutrient solution. The cemented specimen can show higher strength, calcium carbonate content and better homogeneity in a short time, which is more suitable for soil with shallow cementing depth and high strength. (5) the effect of culture environment temperature on the content of calcium carbonate is not significant when the temperature is 20 鈩，
本文编号：2402734
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