| Remarkable achievements have been reached in hydraulic filed for China since the last decades.This not only brings much convenience to people,but also provides important supports to social development.While the hydraulic engineering gradually develops,seepage prevention has always been a focus for engineers.In recent years,microbial induced calcium carbonate precipitation（MICP）technology is becoming a validated method to solve the seepage problem with the interdisciplinary among biology,chemistry,mechanics and material science.MICP has the advantages of simple reaction mechanism,effective and rapid reaction process,easy to control and environmental.Consequently,the application of this method to solve the seepage problem will reap effective benefits in environment and economy.Making use of Sporosarcina pasteurii,the layer effects and impact factors of MICP were experimentally studied in this paper,which provides basic data and scientific basis for the practical application of microbiological layer technology.The main researches and results are presented as follows.（1）To investigate the effect of cementing concentration and cementing time on coating effect.The minimum permeability coefficient of coated samples in test was2.42?10-5cm/s,and it was equivalent to the mixture silt or clay.Results show that the maximum flexural strength was 1.63MPa,while the maximum compressive strength was 1.5MPa.Meanwhile,appropriately increase the concentration of calcium ion and prolonged reaction time can increase the strength of coating,but excessive concentration had obvious inhibitory effect on urease,downing the coating effect.（2）To analyze the impact of the size of sand and the number of layers on the coating effect.It is found that the size of sand was the main factor to affect permeability coefficient.Smaller size gets better seepage control results under the same layer number.And for the identical size,increasing the layer number can also increase the seepage control ability but cannot reduce the permeability coefficient dramatically.（3）To study the varying laws of flexural and compressive strength for layer.The flexural and compressive strength is proportional to the layer number,and its stiffness is also proportional to the layer number.Under the same layer number,the bigger size makes lager strength and the lager stiffness.The flexural and compressive strength reaches its maximum of 4.06 MP and 8.9MPa respectively when the gravel shop layer is 0.3-0.6mm.（4）To research the influence of calcium carbonate.It is resulted that calcium carbonate acts as a gel among the pores of particles,and the flexural and compressive strength is proportional to the content of calcium carbonate. |
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