On the basis of field investigation of engineering geology, rock mass classification is made for a large phosphate mine according to NGI classification method and its rockmass strength is estimated.

• 针对某地下采空区矿柱稳定性问题,在现场工程地质调查的基础上,按照NGI岩体质量分类法对该矿区岩体质量进行了分类,并由此对其岩体强度作出了估算。