Takes the volcanic breccia and tuff at the dam site of a dam project as the research object

and systematically analysis karst erosion in the fissures of volcanic breccia and tuff at the dam site.Engineering geological surveying

drilling

geophysical prospecting

petrographic analysis

water pressure test and water chemistry test are used to the geotechnical investigation.Through the research

the karst erosion of fracture in non-carbonate rocks and its influence law on engineering are revealed.The results show that the calcium-filled fissures are dissolved by groundwater for a long time and then form karst fissure

and mainly develops in fissures with good connectivity.While their influence on the rock mass’s bearing capacity is limited

the primary impacts include enhanced permeability of deep rock masses and the formation of deep confined groundwater.The evaluation methods adopted in this paper can serve as a technical reference for similar engineering projects.