Evaluation on the Deep Geological Environment of Lancang Lead Deposit

摘要

The shallow mine resource is drying up after exploration for more than 600a in Lancang leaddeposit. With the prospecting for deep resource, a middle scale molybdenum and poly metal deposit in more than 1,000m depth from ground surface has been found. But according to the result of analyzing the shallow geo-environment and exposed foundations by drilling, the deep geological environment will be worse than in the shallow. So to evaluate the deep geo-environment will be an important guidance for exploration design and ensure the safety of deep exploration activities and supply an initial theoretic base for scientific timbering design of the laneway. The results of the evaluation show that: 1) the deposit is located in the belt of concentrating structural stresses and the rockmass is cracked and the strength of the rockmass is very low. 2) As surrounding rock, the tuff will be deformed largely which will effect on the stability of laneway. 3) Because of the big depth, it is very difficult to eliminate the impact of groundwater on the surrounding rock. 4) To deal with the harm by groundwater and strength lose of tuff caused by groundwater are the key issue to ensure the safety of exploration. At the end, one study has been proposed: that is the de-formation mechanism of tuff with groundwater under high stress condition that will be a real theoretic foundation for economic and reasonable timbering the wall of laneway.