## 3 Results
### Characteristic of Pore Space Variations in the Interior of Rocks Using NMR  
The T\({}_{2}\) relaxation time in Nuclear Magnetic Resonance (NMR) spectroscopy is a key parameter that is directly influenced by the size, shape, and surface characteristics of the pores where the hydrogen nuclei reside. In porous materials like rocks, larger pores generally result in longer T\({}_{2}\) relaxation times due to slower dephasing of nuclear spins, whereas smaller pores correspond to shorter T\({}_{2}\) relaxation times because of faster dephasing caused by the increased surface area-to-volume ratio. In the present research, pores larger than 0.1 \(\upmu\)m are classified as macropores, whereas pores smaller than 0.1 \(\upmu\)m are designated as small pores. The 0 kW condition is defined as the basalt specimens that have not been subjected to microwave radiation treatment. As demonstrated in Table 3, the Nuclear Magnetic Resonance (NMR) results reveal a progressive increase in porosity within the basalt specimens, corresponding to both the duration and power of microwave radiation applied. This phenomenon can be attributed to microwave radiation facilitating the formation of additional microcracks and pores within the rock's microstructure. The observed increase in porosity, coupled with changes in pore distribution, serves as a robust indicator of microwave-induced damage to the basalt, as illustrated in Figure 6. For example, the porosity of the basalt specimen after 120 s of 6 kW microwave radiation increased by 0.3496% compared to the untreated basalt, while the porosity after 120 s of 3 kW microwave radiation increased by 0.1899% compared to the untreated specimen. Additionally, it is evident that basalt subjected to 6 kW microwave radiation experienced a more significant increase in porosity compared to that subjected to 3 kW radiation. Specifically, the porosity of the basalt after 120 s of 6 kW microwave radiation increased by 0.1597% compared to that after 120 s of 3 kW microwave radiation. Figure 5: (**a**) Changes in longitudinal wave velocity in microwave-treated rocks. (**b**) Variation in the value of \(F_{D}\) with different microwave radiation. \begin{table}
\begin{tabular}{c c c} \hline
**Microwave Power** & **Microwave Radiation Duration** & **Porosity (\%)** \\ \hline
0 kW & 0 s & 0.9099 \\ \hline  & 30 s & 0.9701 \\
3 kW & 60 s & 1.0401 \\  & 90 s & 1.0893 \\  & 120 s & 1.0998 \\ \hline  & 30 s & 0.9824 \\
6 kW & 60 s & 1.2002 \\  & 90 s & 1.2494 \\  & 120 s & 1.2595 \\ \hline \end{tabular}
\end{table} 
Table 3: The porosity of basalt samples after different microwave radiation. Effect of Microwave Radiation on Mechanical Properties of Basalt Specimens Based on Uniaxial Experiments  
The stress-strain curves obtained from uniaxial compression tests on basalt typically exhibit four distinct stages: microcrack compaction, elastic deformation, microcrack expansion, and post-destruction. These stages can be characterized as follows:  
1. Microrack Compaction Stage: During the initial loading phase, pre-existing defects within the specimen gradually close under external stress, accompanied by the formation of a few new microcracks. This stage is marked by a nonlinear stress-strain curve, where relatively large applied stress causes minimal deformation, indicating the compaction effect resulting from initial inhomogeneity. The deformation in this stage is predominantly reversible and elastic. 2. Elastic Deformation Stage: Once the pre-existing defects are fully closed, the material enters a stage of clear linear elastic behavior, where the stress is proportional to the strain. The elastic modulus of the rock is determined from the slope of the curve during this stage, and the deformation remains reversible and elastic. 3. Microcrack Expansion Stage: As the stress continues to increase, new microcracks form, and existing cracks begin to extend and interconnect, resulting in increased  
Figure 6: Pore size distribution of basalt samples after different microwave radiation. plastic deformation.