土壤孔隙数量 影响土壤比重的因素: 土壤比重仅仅取决于土壤固相颗粒的物质组成。 Since a large portion of most soils is composed of particles derived from quartz minerals, the particle density of most soils is near 2. 6g/cc which is the density of quartz. Variations in the particle density are due to the presence of heavier minerals like iron oxides or lighter organic components 表4-1土壤中常见组分的密度(克/厘米3) 2.60~2.68 赤铁矿 4.90~5.30 正长石 磁铁矿 5.03~5.18 斜长石 2.62~2.76 水铝石 2.30~240 白云母 2.77~288 高岭石 2.61~268 黑云母 2.70~3.10 蒙皂石 2.53~2.74 角闪石 2.85~3.57 伊利石 3.15~3.90 纤铁矿 腐殖质 140~1.80
一.土壤孔隙数量 影响土壤比重的因素： 土壤比重仅仅取决于土壤固相颗粒的物质组成。 Since a large portion of most soils is composed of particles derived from quartz minerals, the particle density of most soils is near 2.6 g/cc, which is the density of quartz. Variations in the particle density are due to the presence of heavier minerals like iron oxides or lighter organic components. 表 4-1 土壤中常见组分的密度 (克/厘米 3 ) 石 英 正长石 斜长石 白云母 黑云母 角闪石 辉 石 纤铁矿 2.60～2.68 2.54～2.57 2.62～2.76 2.77～2.88 2.70～3.10 2.85～3.57 3.15～3.90 3.60～4.10 赤铁矿 磁铁矿 三水铝石 高岭石 蒙皂石 伊利石 腐殖质 4.90～5.30 5.03～5.18 2.30～2.40 2.61～2.68 2.53～2.74 2.60～2.90 1.40～1.80
土壤孔隙数量 土壤比重值:绝大多数矿物的比重为2.60~2.70之间,对于 矿质土壤而言,经常取其中间值2.65作为土壤比重近视值。 土壤比重与质地关糸:砂质土壤比重值与石英接近,而粘 质土壤含铁、镁矿物较多,比重一般较大。 有机质合量高的土壤比重小。所以,耕层土壤比重比底层 土壤小。 问题:1.比重与土壤压实程度有关糸吗? 2.土壤比重与土壤干湿程度有关糸吗? 3.土壤比重具有诊断特性的意义何在(土壤相对稳定 的性质)表4-2一种森林土壤表层各级土粒的密度 粒级(粒径毫米) 腐殖质(克/千克) 密度(克/厘米3) 全土样 29.5 2.62 0.10~005 0 2.66 0.05~001 4.3 2.66 0.01~0005 14.8 2.62 0.005~0.001 53.7 <0.001 64.2 2.59
一.土壤孔隙数量 土壤比重值： 绝大多数矿物的比重为2.60~2.70之间，对于 矿质土壤而言，经常取其中间值2.65作为土壤比重近视值。 土壤比重与质地关系：砂质土壤比重值与石英接近，而粘 质土壤含铁、镁矿物较多，比重一般较大。 有机质含量高的土壤比重小。所以，耕层土壤比重比底层 土壤小。 问题：1.比重与土壤压实程度有关系吗? 2.土壤比重与土壤干湿程度有关系吗？ 3.土壤比重具有诊断特性的意义何在（土壤相对稳定 的性质） 表 4－2 一种森林土壤表层各级土粒的密度 粒级（粒径毫米） 腐殖质（克/千克) 密度(克/厘米 3 ) 全土样 0.10～0.05 0.05～0.01 0.01～0.005 0.005～0.001 <0.001 29.5 0 4.3 14.8 53.7 64.2 2.62 2.66 2.66 2.62 2.59 2.59
土壤孔隙数量 土壤比重测定方法:比重瓶法 注意!测定 比重用扰动 土
一.土壤孔隙数量 土壤比重测定方法：比重瓶法 注意！测定 比重用扰动 土
Specific gravity(G is a property of the mineral or not to 500 or 1000 ml rock material forming soil grains same scale] density jar Pycnometer) It is defined as for coarse soils mass of a soil grain 50 ml SG Bottle s mass of an equal volume of water for fine soils Method of measurement For fine soils a 50 ml density bottle may be used; for coarse soils a 500 ml or 1000 ml jar. The jar is weighed empty(Mi). a quantity of dry soil is placed in the jar and the jar weighed(M2 ). The jar is filled with water, air removed by stirring, and weighed again(M3). The jar is emptied, cleaned and refilled with water-and weighed again(Md) Mass of so il Mass of water displaced by soil 2 The range ofGs for common soils is 2.64 to 2.72
Specific gravity (Gs ) is a property of the mineral or rock material forming soil grains. It is defined as Method of measurement For fine soils a 50 ml density bottle may be used; for coarse soils a 500 ml or 1000 ml jar. The jar is weighed empty (M1 ). A quantity of dry soil is placed in the jar and the jar weighed (M2 ). The jar is filled with water, air removed by stirring, and weighed again (M3 ). The jar is emptied, cleaned and refilled with water - and weighed again (M4 ). [The range of Gs for common soils is 2.64 to 2.72]
Volume-weight properties volumes Soil sample Air volume of Voids ater Solid Volume of Solids Soil model The volume-weight properties of a soil define its state Measures of the amount of void space, amount of water and the weight of a unit volume of soil are required in engineering analysis and design Soil comprises three constituent phases Solid: rock fragments, mineral grains or flakes, organic matter Liquid: water, with some dissolved compounds(e.g. salts) Gas: air or water vapour In natural soils the three phases are intermixed. To aid analysis it is convenient to consider a soil model in which the three phases are seen as separate, but still in their correct proportions
Volume-weight properties The volume-weight properties of a soil define its state. Measures of the amount of void space, amount of water and the weight of a unit volume of soil are required in engineering analysis and design. Soil comprises three constituent phases: Solid: rock fragments, mineral grains or flakes, organic matter. Liquid: water, with some dissolved compounds (e.g. salts). Gas: air or water vapour. In natural soils the three phases are intermixed. To aid analysis it is convenient to consider a soil model in which the three phases are seen as separate, but still in their correct proportions