| Under the action of tectonic stress,structural surfaces such as joints and cracks are generated inside the rock mass.Affected by these structural planes,geological disasters such as structural surface cracks and landslides frequently occur in the project.Therefore,strengthening the structural planes is of great significance to reduce and avoid the occurrence of engineering geological disasters.As a new type of rock mass reinforcement technology,MICP(Microbial Induced Carbonate Precipitation)technology has the advantages of simple mechanism,high efficiency,no pollution,and easy control compared to traditional grouting methods.Aiming at the hard structural surface and the weak structural surface,the paper studies the strengthening and repair of the rock mass structural surface based on the MICP technology.Bacterial optimization culture experiments were carried out,using hard structure surface injection,weak structure surface geotextile wrap soaking and other repair methods,with the help of XRD identification,EDS analysis,SEM observation,indoor mechanics experiments and strength theory analysis,etc.,around the mechanical properties of the repaired structural surface Research on key issues such as improvement and destruction mode.The specific research work is as follows:(1)Laboratory activation culture test of Bacillus pasteurii.The optimal culture conditions for the bacterial solution are pH 8,temperature 30℃,culture time 22-26h.Ca2+concentration in the cement solution is 0.5mol/L,and urea concentration is 0.75.mol/L.(2)Use sandstone to make hard structure interview pieces,use syringe to simulate grouting anchors,and replace cement grouting material with chemical grouting materials to carry out MICP repair test research on hard structure surfaces.The weak structure interview piece was made through the steel mold,and the weak structure surface MICP repair test research was carried out by using the geotextile wrapping soaking method.By means of XRD,EDS and SEM,the phase analysis and microscopic observation of precipitates at the structural plane were carried out,and the mechanism of micp repair on the structural plane was explained from the microscopic level.(3)The shear test was performed on the rigid structural surface before and after the repair with a straight shear instrument,and the shear resistance parameters of the rigid structural surface before and after the repair were obtained.Based on the analysis of Jaeger criterion,the damage changes of the hard structure interview piece before and after repair are obtained.With the help of conventional triaxial tests to verify the analysis results,the shear resistance parameters of the structural surface and the mechanical properties and failure modes of the test piece are taken into consideration for the weak structure The effect of surface repair was evaluated and analyzed.(4)The shear test was performed on the weak structural surface before and after the repair with a direct shear instrument,and the shear resistance parameters of the weak structural surface before and after the repair were obtained.Based on the analysis of Jaeger criterion,the damage changes of the specimens with weak interlayers before and after repair are obtained.The analysis results are verified by uniaxial compression tests,and the shear resistance parameters of the structural surface and the mechanical characteristics and failure modes of the specimens are considered to be weak The repair effect of the structural plane is evaluated and analyzed.According to the above research,using MICP technology to repair the rock mass structural surface can enhance the integrity of the rock mass and improve the mechanical strength.This method also has the advantages of simple mechanism,low energy consumption and environmental protection.Practical significance and broad application prospects. |
