Application Of Microbial Induced Calcium Carbonate Precipitation In Reinforcement Of Fractured Rock Mass

In the long geological evolution and engineering excavation disturbance,there are a lot of joints and cracks in the rock mass.Because of the existence of the fissure rock mass,the landslide and other disasters seriously threaten people's lives and safety,it is of great significance to strengthen the fissure rock mass.Based on the characteristics of difficult control of cement slurry,unenvironmental protection of chemical materials and high cost of ultra-fine cement,this paper attempts to introduce microbial induced calcite precipitation?MICP?to reinforce soil for rock fracture repair.In this paper,Sporosarcina pasteurii was firstly cultured in the laboratory,and then the media and structural surface factors affecting the effect of MICP on rock fracture reinforcement were tested.Finally,ANSYS software was used for numerical simulation of rock slope reinforcement,and the main research results were as follows:?1?When Sporosarcina pasteurii is cultured in the laboratory,the bacterial solution should be selected for about 20h,and calcium chloride should be used as the calcium source in the cementing solution.Rock specimens strengthened with MICP must undergo grouting for more than 10 rounds.?2?Filling medium greatly improves the tensile strength of the specimen.In the case of the same rock,the reinforcement effect is positively correlated with the compactness and particle size of the filling medium.In this experiment,the amount of CaCO₃ generated is positively correlated with the density of sandy soil.In different filling media,the amount of CaCO₃ generated is silty soil,coarse grained soil and sandy soil from large to small.In the spatial distribution,the amount of CaCO₃decreases with the increase of the distance from the grouting mouth.Gelling minerals formed in different media have different morphology.?3?The tensile strength of the specimen is positively correlated with the roughness.The amount of CaCO₃ increases with the increase of roughness coefficient.In the spatial distribution,it can be seen that the amount of CaCO₃ generated by the specimen decreases with the increase of the grouting port distance.The structure surface factors had little effect on the morphology of gelled minerals induced by microorganisms.?4?Media factors affect the effect of MICP reinforcement specimens because of the formation of"contact points",the amount of CaCO₃ that acts as cementing and filling,and the difference between the pores of media particles.The major factors affecting the amount of CaCO₃ are the pore size of medium particles and the transformation between free and attached bacteria.The main factor influencing the crystal morphology of CaCO₃ in this experiment is the pH difference of the medium.?5?After the reinforcement with MICP technology,the stability of rock slope has been greatly improved.The safety coefficient of rock slope has a linear relationship with cohesive force and Angle of internal friction,and the influence of cohesive force is more significant than Angle of internal friction.The elastic modulus has little effect on the safety factor of the structure.