Dolomite is formed via dolomitization

a process that enhances porosity. Investigating the influence of dolomite as a characteristic mineral on the deterioration of the physical and mechanical properties of siltstone is significant for the design and stability prediction of deep underground engineering. This study employs X-ray fluorescence spectrometer (XRF)

X-ray diffraction (XRD)

microscopic analysis

ultrasonic wave velocity measurements

and nuclear magnetic resonance testing to quantify dolomite’s impact on siltstone’s physical parameters. Brazilian splitting tests

monotonic loading

and cyclic loading-unloading experiments reveal the evolution of mechanical parameters

including tensile and compressive strengths. An apparent elastic-viscous-plastic damage model is developed

and dolomite-induced deterioration mechanisms are investigated using computed tomography (CT) and scanning electron microscopy (SEM). The results indicate that: 1) Dolomite content enhances particle roundness

weakens intergranular interlocking

and creates distinct boundary pores with calcite

leading to enhanced pore connectivity and a 2.77-fold increase in porosity. 2) Dolomite presence reduces maximum tensile strain

decreases compressive strength by 14.5%

extends the compaction phase by 9%

and shortens the stable crack propagation phase by 12%. 3) A larger cyclic loading-unloading difference correlates with higher damage values. Dolomite-free rocks exhibit significant damage variation

with rapid early-stage increases followed by slower growth

whereas dolomite-containing rocks show more stable damage progression

with dolomite inducing more pronounced elastic-viscous-plastic damage accumulation. 4) Cracks in dolomite-free samples are bent

dissipating more energy with lower energy storage values

while those in dolomite-containing samples are straight

dissipating less energy with higher energy storage values. Dolomite enhances porosity

facilitating crack propagation and increasing the proportion of tensile cracks.