ABSTRACT
ABSTRACT: This paper presents a comprehensive study of the unloading relaxation, damage fracture, and degradation of the mechanical parameters of surrounding rocks in underground caverns during excavation using acoustic velocity test, borehole camera test, and borehole elastic modulus test. First, the range of excavation damaged zone is determined by the results of acoustic velocity test. Then, from borehole camera images, information of the distribution and evolution of fissures and cracks during blasting excavation is obtained. Finally, the relationship between elastic modulus and acoustic velocity is established by the borehole elastic modulus tests and acoustic velocity results. The mechanical parameters of the excavation damaged zone and surrounding undisturbed rocks of underground caverns are directly determined by in situ geophysical and geotechnical tests. It provides a direct basis for feedback analysis of displacement monitoring and advanced deformation forecasting of surrounding rocks in underground caverns.
