基于微生物诱导碳酸钙沉积的防风固沙试验研究

Wind-breaking and Sand-fixing Experimental Research Based on Microbial Induced Carbonate Precipitation

为将微生物诱导碳酸钙沉积(MICP)技术用于风沙土的表面固化,需要对这一过程的影响因素和规律进行探究.利用标准砂模拟风沙土进行相关试验,试验变量包括处理液浓度、细菌浓度、处理液体积和处理温度,从风洞试验、表面强度试验、碳酸钙含量测定三个方面对处理后的试样进行对比评估.结果表明,试样表面由于生成了碳酸钙沉淀而形成了一层硬壳层,赋予试样一定的抗风侵蚀能力.当处理液体积为4 L/m^2,温度为20℃,处理液浓度为0.1 M,细菌浓度OD_(600)=0.6时,MICP加固的试样开始具备良好的抗风侵蚀能力.

In order to apply the microbial induced carbonate precipitation(MICP)approach to stabilize desert sand and to against erosive force of wind,the influencing factors and the functional rules of the MICP process need to be explored.In this paper,the standard sand is used to imitate desert sand to be conducted related experiments.The main test variables include the concentration of treating fluid,the concentration of bacteria,the volume of treating fluid and the treatment temperature.The wind tunnel test,the surface strength test,and the measurement of calcium carbonate content were conducted.The results show that a calcite consolidation layer was formed on the surface of the sample due to the cementation by calcium carbonate precipitation generated in MICP process,which gives the sample a better wind erosion resistance.The surface strength of the hard shell layer is an important index to characterize the wind erosion resistance of the samples.Increasing the volume and the concentration of treating fluid,that is,increasing the amount of reactants,increase the formation of calcium carbonate and finally enhance the surface strength of the hard shell layer.Raising the treatment temperature and the concentration of bacteria would increase the amount of calcium carbonate by increasing the activity of bacteria,and finally enhance the surface strength of the hard shell layer.