Energy evolution and damage deformation behavior of cemented broken coal specimen under triaxial compression condition

Coal is a major energy source, and deep coal mining often leads to fractured coal around roadways. Grouting is a common method used to reinforce fractured rock masses, where the slurry encases coal particles, forming a cemented broken coal (CBC) body. The content of coal particles (CP) significantly affects the energy characteristics of CBC specimens. To investigate this, a series of triaxial compression tests and triaxial unloading tests were conducted on CBC specimens with varying CP contents. The results indicate that as CP content increases, both peak strength and cohesion decrease, while the internal friction angle increases in both tests. In the triaxial unloading tests, specimens with higher CP content showed tensile-shear failure. Additionally, energy trends during damage were similar in both tests. In triaxial compression tests, dissipated energy increased with CP content, while in the triaxial unloading test, it initially rose and then fell. During the unloading phase of the triaxial unloading tests, the CBC specimen with 40 % CP content exhibited the most significant change in energy increment and its rate. Analysis of damage and deformation characteristics indicated that damage, deformation, and dilation were effectively restrained in CBC specimens with 40 % CP content during unloading.