Geomechanical characterization of carbonates of the Sete Lagoas Formation (Bambuí Group)

Abstract The geomechanical properties of rock masses must be identified to assess their quality and employability; however, the methodologies may differ depending on the lithotype and analytical purposes. The present study aimed to estimate the not-well-known physical-mechanical properties of three types of carbonate rocks (calcarenite, calcilutite, and marble) of Sete Lagoas Formation, which are not recognized in scientific literature, southeast Brazil. These are important rocks from an economic point of view, as they comprise an important input for cement, fertilizers and construction material. Both physical indexes (apparent porosity, apparently dry and saturated specific mass, apparent absorption capacity and wave propagation velocity) and mechanical properties (uniaxial compression, point load and slake durability) were determined. Mechanical tests for these three rock types were correlated to those of other carbonate rocks from other countries, for comparisons. The results showed that the lithotypes under study are peculiar in terms of porosity, wave propagation velocity and strength. Also found were a very high durability and a very good correlation between specific mass and uniaxial compressive strength.

摘要 为评估岩体质量与可利用性，需明确其岩土力学特性；但研究方法会因岩性类型及分析目标的不同而有所差异。本研究旨在估算巴西东南部塞特拉戈阿斯组（Sete Lagoas Formation）中三种此前未在科学文献中得到充分记载的碳酸盐岩——钙屑灰岩（calcarenite）、泥晶灰岩（calcilutite）及大理岩（marble）的鲜为人知的物理力学特性。从经济价值视角来看，这类岩石具备重要应用价值，可作为水泥、肥料与建筑材料的核心原料。本研究测定了相关物理指标（表观孔隙率、表观干密度与饱和密度、表观吸水率及波传播速度）与力学性能（单轴抗压强度、点荷载强度及耐崩解性）。为开展对比分析，本研究将这三种岩石的力学测试结果与其他国家的碳酸盐岩测试数据进行了关联比对。结果表明，本次研究涉及的岩型在孔隙率、波传播速度及强度方面均具有独特性；同时还发现，此类岩石具备极高的耐崩解性，且密度与单轴抗压强度之间存在极佳的相关性。