Effects of Ca(OH)2 on mechanical damage and energy evolution characteristics of limestone adsorbed with H2S

Abstract

The occurrence of hydrogen sulfide (H2S) gas gusher accidents is a worrying engineering disaster during tunnel construction travel through stratum adsorbed with H2S. To mitigate the risks associated with H2S, alkaline solutions are applied within the tunnel and injected into the rock mass ahead of the tunnel face to neutralize and eliminate the adsorbed H2S. Samples from the Huangjiagou tunnel in southwestern China are systematically investigated to understand the interaction between H2S-adsorbed limestone and calcium hydroxide (Ca(OH)2) solutions at concentrations of 1, 3, and 5%. The results indicate that exposure of the limestone to Ca(OH)2 solution leads to the erosion of aluminum silicate minerals and the subsequent precipitation of potassium feldspar crystals. The uniaxial compressive strength and modulus of elasticity of the limestone decreased by 48.82 and 28.31%, respectively, following an exponential trend as the concentration of Ca(OH)2 solution increased. Additionally, an increase in the number of abrupt energy changes detected via acoustic emission is observed in limestone treated with higher concentrations of alkaline solutions. Energy evolution analysis indicates that alkaline-treated limestone exhibits significantly enhanced energy dissipation capacity during the loading process, making dissipative energy more likely to dominate.

Keywords

• tunnel engineering
• h2s treatment
• ca(oh)2 injection
• mineral changes
• rock mechanics damage