微生物固化风沙土的保水性能试验研究

Experimental Study on Water Retention Properties of Microbially Stabilized Aeolian Sand Soil

[目的]研究微生物诱导碳酸钙沉淀(MICP)固化风沙土的性能,为MICP技术在固化风沙土以及恢复生态等方面提供理论依据。[方法]采用MICP技术对风沙土进行不同次数的固化处理,通过扫描电镜和光学显微镜对固化风沙土的微观结构进行分析,并测试分析固化试样的基本物理性质和保水性。[结果]通过MICP处理的风沙土,在风沙土颗粒之间有碳酸钙晶体生成,将沙土颗粒胶结在一起,使松散的风积沙固化成具有一定强度的整体;随着固化次数的增加,固化风沙土的厚度、干密度、碳酸钙含量逐渐增大,渗透系数逐渐减小,固化厚度由3.38 mm增加至11.28 mm,干密度由原沙的1.61 g/cm^(3)增加至2.05 g/cm^(3),碳酸钙含量由8.99%增加至13.08%,渗透系数由原沙的1.06×10^(-3)cm/s减少至2.35×10^(-4)cm/s;当固化处理次数不大于5次时,保水率随固化处理次数的增加而增大,固化试样的保水性能有所改善,固化处理超过5次后,保水性能则有所下降。[结论]采用MICP技术固化的风沙土,可明显改善风沙土的干密度、渗透性能和保水性。综合考虑固化效果、保水性及经济性,建议最佳的固化处理次数为3次。这样可有效防治风蚀并保持土壤水分以利于生态修复。

[Objective]The performance of microbial induced calcium carbonate precipitation(MICP)to stabilize aeolian sand soil was studied in order to providing a theoretical basis for MICP technology in stabilize aeolian sand soil and restoring ecology.[Methods]The microstructure of aeolian sand soil was analyzed by use of scanning electron microscopy and optical microscopy on an aeolian sand soil stabilized with MICP.The test analyzed the basic physical properties and water retention of stabilized specimens.[Results]The aeolian sand soil treated with MICP had calcium carbonate crystals generated between the aeolian sand particles that cemented the sand particles together and solidified the loose aeolian sand into a whole with a certain strength.As curing time increased,the thickness,dry density,and calcium carbonate content of cured aeolian sand gradually increased,the permeability coefficient gradually decreased,the stabilized thickness increased from 3.38 mm to 11.28 mm,the dry density increased from 1.61 g/cm 3 for the original sand to 2.05 g/cm^(3),the calcium carbonate content increased from 8.99%to 13.08%,and the permeability coefficient decreased from 1.06×10^(-3)cm/s for the original sand to 2.35×10^(-4)cm/s.When the number of curing treatments was not more than five times,the water retention rate increased with increasing number of curing treatments,and the water retention of the stabilized specimen increased.After more than five curing treatments,water retention decreased.[Conclusion]Aeolian sand soil stabilized by MICP technology can significantly improve the physical and mechanical properties and water retention of aeolian sand soil.Considering this stabilizing effect,water retention,and economics,the best stabilizing treatment time is three times.Thus,we can effectively prevent wind erosion,maintain soil moisture,and facilitate ecological restoration.