常州粉砂层中“岩块”探测及其性状、成因分析

Detection and analysis on the characters and forming of “rock blocks” in Changzhou silt sand

常州某地涵勘察时,发现一层粉砂夹“岩块”,规模较大,较为罕见。通过勘探、物探及施工开挖等多种手段,查明了该层分布规律。通过室内试验及岩矿鉴定,查明该层“岩块”物理力学性质及矿物组成,该层“岩块”含粉砂或粉砂碎屑约60%、方解石约40%,室内定名为钙质粉砂岩,强度较高,为软岩—较软岩。土中岩石成因通常分为外来和内在生成两种,通过分析,排除了外来的可能性,确定该层“岩块”为内在形成,是一种钙质结核,其成因为CaCO_(3)多次溶解析出、富集而成。

During the investigation of the culvert in Changzhou,a layer of silt with “rock blocks” is found which is large and rare.Through the exploration,geophysical prospecting and excavation,the distribution law of this layer is found out.Through the indoor tests and mineral identification,the physical and mechanical properties and mineral composition in the layer are identified.The “rock blocks” in this layer contain 60% silt or silt debris,and 40% calcite.The indoor name is calcareous siltstone with high strength,which is soft rock-softer rock.The rock in soil is usually divided into two types:the external and internal formation.Through the analysis,the possibility from external formation is excluded.It is determined that the “rock blocks” in this layer is formed internally and is a kind of calcareous tuberculosis,which is concentrated by the multiple dissolution and precipitation of CaCO_(3).