CY-309厚煤层(分层同采)采区巷道布置 规格:1.2×0.8×0.7 CY-309厚煤层(分层同采)采区巷道布置CY-309厚煤层(分层同采)采区巷道布置CY-309厚煤层(分层同采)采区巷道布置CY-309厚煤层(分层同采)采区巷道布置