Damage properties of basaltic rocks under multilevel stress loading and microwave irradiation

Abstract

The deterioration of mechanical strength and damage characteristics of rock under microwave is the primary focus in evaluating the applicability of microwave-efficient rock-breaking technology. This study analyzed the mechanical strength deterioration and damage characteristics of basalt under microwave irradiation and performed an X-ray digital radiography (DR) image analysis of the damage process of basalt under a multilevel stress loading (MSL) path. The research results show that basalt with a large porosity had a better thermal effect on microwave irradiation and significantly enhanced the resistance to deterioration. The microwave thermal effect of polar minerals is critical to plastic failure behavior. This study also proposes a rock damage characteristic evaluation model based on X-ray DR image quantitative analysis and X-ray absorption dose threshold segmentation. The image analysis model can accurately describe the evolution process of rock damage characteristics. A modified model for basalt damage characteristic analysis is provided. The elastic–plastic damage model based on the Cast3M finite element software was compared with the proposed damage model based on X-ray DR images. The calculated results show that the change in the damage zone was consistent with the damage crack propagation process of basalt. Therefore, the proposed damage evaluation model can provide guidance for the scientific evaluation of the adaptability of microwave-assisted tunnel boring machine (TBM) efficient rock-breaking technology.