We find the movement of bacteria in the silty sand is limited for the smaller pore volume and larger specific surface area of silt particles which affects the effect of microbial solidification of silty sand.In this study,the method is improved on the basis of the original biocenmentation technology.Ultrasonic wave is used to break the cell of bacteria to help the solution of bacteria to the better strengthen silty sand.A series of tests,such as cell lysis of the urea hydrolysate bacteria,the activity determination of the crude enzyme solution,the penetration test and the test of the silty sand treatment,are carried out. It is proved that the urease activity of the solution is greatly improved after the cell lysis of the bacteria.According to the common volume ratio of 1:3,urea of 0.5 mol/L can be completely reacted in 48 hours by the crude enzyme which means that it is feasible to use the crude enzyme solution for solidification of soil.For the silty sand with 15% powder particles,the crude enzyme solution has a stronger penetration and a more uniform treatment effect by compareing with bacteria which means it can treat sand at a deeper place. The crude enzyme solution has a broad application prospect in the improvement of silty sand and prevention of soil liquefaction.%粉粒较小的孔隙体积以及较大的比表面积限制了细菌在土体中的迁移,影响到了微生物固化技术处理粉质砂土的效果.在原有微生物固化技术的基础上进行了改良,利用超声波将细菌破碎后再进行土体的加固处理.开展了尿素水解细菌的破胞、破胞酶液的活性测定、穿透试验、粉质砂土处理试验等一系列试验.证明了破胞后溶液的脲酶活性发生了显著的提升,按照1:3的常用体积比,破胞酶液在48 h内即可将0.5 mol/L的尿素完全反应,破胞酶液用于固化处理是可行的.对于15%粉粒含量的粉质砂土,破胞酶液相比于原细菌有着更强的穿透性和更均匀的处理效果,可以处理更深层的土体.微生物破胞酶液在粉质砂土土体改良、砂土地基防液化等方面有着广阔的应用前景.
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