Shear cell measurements of the internal and wall friction angles of pyroclastic material: implications for flowability of pyroclastic density currents

Dataset for measurements of internal and wall friction angles of pyroclastic material. Dataset includes the measurements of the normal stress, σ, and the shear stress, τ for fine and coarse pyroclastic material. The internal friction angles were measured for pre-shear normal stress, σp = 9, 7.5, 6, 4.5, 3, and 1.5 kPa. The wall friction angles were measured for pre-shear normal stress, σp = 9, 6, and 3 kPa for sandpaper of grit 40, 60, 120, 240, 320, and 400.本数据集用于火山碎屑物质（pyroclastic material）的内摩擦角与壁面摩擦角测量。 数据集涵盖细粒与粗粒火山碎屑物质的法向应力σ与剪应力τ的测量数据。内摩擦角的测量设置了预剪法向应力σ_p分别为9、7.5、6、4.5、3及1.5 kPa的多组工况；壁面摩擦角的测量则针对40、60、120、240、320及400目砂纸，在预剪法向应力σ_p分别为9、6及3 kPa的工况下完成。