基于脲酶诱导碳酸钙沉积的微生物矿化技术在分散性土改良中应用的试验研究

Experimental study on bio-mineralization for dispersed soil improvement based on enzyme induced calcite precipitate technology

将基于脲酶诱导碳酸钙沉积(EICP)的微生物矿化技术运用于分散性土的改良。以内蒙古呼伦贝尔某水库工程的筑坝土料作为岩土基质,通过针孔试验、双密度计试验和碎块试验,对微生物矿化改良前后的土样进行分散性试验鉴定和评价。试验结果显示,经过微生物矿化改良后的土样抗分散能力明显增强,特别是以脲酶溶液制备的微生物改性剂,改良后土样在针孔试验中经历了50、180、380 mm以及1020 mm的水头后,流出水始终保持清澈透明的状态,且出水口平整;针孔尺寸保持不变,收集针孔试验后的土样进行碎块试验,未出现胶粒的分散状况。双密度计试验中测得经脲酶溶液改良后土样的分散度低于30%,较原土样的分散度降低约50%,土样由分散性转变为非分散性;经微生物菌液改良后土样的分散度为41.1%,较原土样的分散度降低22%,土样由分散性转变为过渡性。以脲酶溶液制备的微生物改性剂,在粒径细小的黏性土中发挥矿化作用更加充分,就分散性土的改良和提高抗分散能力而言,优于以微生物菌液制备的微生物改性剂。首次将脲酶诱导碳酸钙沉积(EICP)技术应用于分散性土的改良,这是绿色微生物矿化技术与水利筑坝材料改良相结合的创新,在筑坝填料分散性土的改良中有着良好的应用前景。

Enzyme induced calcite precipitation(EICP)technology is applied to mineralize dispersed soil and improve dispersion resistance.The dispersed soil was sampled from a dam filler of reservoir in Hulunbuir,Inner Mongolia,and acted as parent soil during mineralization process.The dispersion of the soil sample before and after bio-mineralization was identified and evaluated by pinhole test,double hydrometer test and broken soil test.The results showed that the anti-dispersion ability of soil improved by bio-mineralization was significantly enhanced,especially by the microbial modifier prepared by urease solution.When the improved soil samples experienced 50,180,380 mm and 1020 mm water heads in the pinhole test,the outflow water always remained clear and transparent,the water outlet was flat,and the size of the pinhole remained unchanged.The soil samples after the pinhole test were collected for broken soil test,and there was no colloidal particle dispersion during the test.During the double hydrometer test,it was found that the dispersity of soil samples improved by urease solution was less than 30%,which was reduced by about 50%compared to that of the unimproved dispersed soil,and the properties of soil sample changed from dispersive to non-dispersive.But for soil samples improved by microbial solution,the dispersity was 41.1%,which was 22%lower than that of the unimproved dispersed soil,the properties of soil sample changed from dispersive to transitional.The microbial modifier prepared by urease solution played a more adequate role in the mineralization process for fine-grained soil,and it was superior to the microbial modifier prepared by microbial solution in terms of the improvement of dispersed soil modification and the anti-dispersion ability improvement.In this paper,it is the first time that the bio-mineralization base on EICP technology was applied to the improvement of dispersed soil.This is an innovation combining green bio-mineralization technology with dispersed soil improvement in water conservancy damming engineering.It has a good application prospect in improving the dispersed soil of damming filler.