Abstract
Cracks in underground rock masses cause gas leakage, seepage, and water inflow. To realize calcium carbonate deposition and mineralization filling in rock cracks, microencapsulated bacterial spores were prepared by an oil phase separation method. To optimize the microorganism growth conditions, the effects of microcapsules with various pHs, particle sizes, and amounts on microcrack self-healing were investigated through an orthogonal test, and the best conditions for repairing the cracks using microencapsulated Bacillus sphaericus were obtained. Infrared analysis and scanning electron microscopy were used to observe the morphological characteristics and coating performance of the microcapsules. The results showed that the microcapsules contained functional groups in the core and wall materials. The surfaces of the microcapsules prepared by the test were rough, which was beneficial for adhesion onto the fracture surface. X-ray diffraction analysis, X-ray photoelectron spectroscopy, and thermal analysis were conducted. The results showed that the microcapsules with pH = 8 and a particle size of 100 μm had the highest thermal decomposition temperature and the best thermal stability. The elements of the core and wall materials were detected in the microcapsules, and the coating had a beneficial effect. The compression and acoustic emission tests of the specimens embedding microbial capsules with different contents under different working conditions revealed that the two fractures of the specimen were due to the rupture of the microcapsule and the rupture of the rock specimen, indicating the best mechanical triggering properties and compressive properties of the microcapsule.